mm/hmm.c: remove superfluous RCU protection around radix tree lookup

[linux/fpc-iii.git] / drivers / usb / dwc3 / gadget.c

// SPDX-License-Identifier: GPL-2.0
/*
 * gadget.c - DesignWare USB3 DRD Controller Gadget Framework Link
 *
 * Copyright (C) 2010-2011 Texas Instruments Incorporated - http://www.ti.com
 *
 * Authors: Felipe Balbi <balbi@ti.com>,
 *          Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 */

#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/list.h>
#include <linux/dma-mapping.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

#include "debug.h"
#include "core.h"
#include "gadget.h"
#include "io.h"

/**
 * dwc3_gadget_set_test_mode - enables usb2 test modes
 * @dwc: pointer to our context structure
 * @mode: the mode to set (J, K SE0 NAK, Force Enable)
 *
 * Caller should take care of locking. This function will return 0 on
 * success or -EINVAL if wrong Test Selector is passed.
 */
int dwc3_gadget_set_test_mode(struct dwc3 *dwc, int mode)
{
        u32             reg;

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_TSTCTRL_MASK;

        switch (mode) {
        case TEST_J:
        case TEST_K:
        case TEST_SE0_NAK:
        case TEST_PACKET:
        case TEST_FORCE_EN:
                reg |= mode << 1;
                break;
        default:
                return -EINVAL;
        }

        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        return 0;
}

/**
 * dwc3_gadget_get_link_state - gets current state of usb link
 * @dwc: pointer to our context structure
 *
 * Caller should take care of locking. This function will
 * return the link state on success (>= 0) or -ETIMEDOUT.
 */
int dwc3_gadget_get_link_state(struct dwc3 *dwc)
{
        u32             reg;

        reg = dwc3_readl(dwc->regs, DWC3_DSTS);

        return DWC3_DSTS_USBLNKST(reg);
}

/**
 * dwc3_gadget_set_link_state - sets usb link to a particular state
 * @dwc: pointer to our context structure
 * @state: the state to put link into
 *
 * Caller should take care of locking. This function will
 * return 0 on success or -ETIMEDOUT.
 */
int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
{
        int             retries = 10000;
        u32             reg;

        /*
         * Wait until device controller is ready. Only applies to 1.94a and
         * later RTL.
         */
        if (dwc->revision >= DWC3_REVISION_194A) {
                while (--retries) {
                        reg = dwc3_readl(dwc->regs, DWC3_DSTS);
                        if (reg & DWC3_DSTS_DCNRD)
                                udelay(5);
                        else
                                break;
                }

                if (retries <= 0)
                        return -ETIMEDOUT;
        }

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;

        /* set requested state */
        reg |= DWC3_DCTL_ULSTCHNGREQ(state);
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        /*
         * The following code is racy when called from dwc3_gadget_wakeup,
         * and is not needed, at least on newer versions
         */
        if (dwc->revision >= DWC3_REVISION_194A)
                return 0;

        /* wait for a change in DSTS */
        retries = 10000;
        while (--retries) {
                reg = dwc3_readl(dwc->regs, DWC3_DSTS);

                if (DWC3_DSTS_USBLNKST(reg) == state)
                        return 0;

                udelay(5);
        }

        return -ETIMEDOUT;
}

/**
 * dwc3_ep_inc_trb - increment a trb index.
 * @index: Pointer to the TRB index to increment.
 *
 * The index should never point to the link TRB. After incrementing,
 * if it is point to the link TRB, wrap around to the beginning. The
 * link TRB is always at the last TRB entry.
 */
static void dwc3_ep_inc_trb(u8 *index)
{
        (*index)++;
        if (*index == (DWC3_TRB_NUM - 1))
                *index = 0;
}

/**
 * dwc3_ep_inc_enq - increment endpoint's enqueue pointer
 * @dep: The endpoint whose enqueue pointer we're incrementing
 */
static void dwc3_ep_inc_enq(struct dwc3_ep *dep)
{
        dwc3_ep_inc_trb(&dep->trb_enqueue);
}

/**
 * dwc3_ep_inc_deq - increment endpoint's dequeue pointer
 * @dep: The endpoint whose enqueue pointer we're incrementing
 */
static void dwc3_ep_inc_deq(struct dwc3_ep *dep)
{
        dwc3_ep_inc_trb(&dep->trb_dequeue);
}

void dwc3_gadget_del_and_unmap_request(struct dwc3_ep *dep,
                struct dwc3_request *req, int status)
{
        struct dwc3                     *dwc = dep->dwc;

        req->started = false;
        list_del(&req->list);
        req->remaining = 0;

        if (req->request.status == -EINPROGRESS)
                req->request.status = status;

        if (req->trb)
                usb_gadget_unmap_request_by_dev(dwc->sysdev,
                                &req->request, req->direction);

        req->trb = NULL;
        trace_dwc3_gadget_giveback(req);

        if (dep->number > 1)
                pm_runtime_put(dwc->dev);
}

/**
 * dwc3_gadget_giveback - call struct usb_request's ->complete callback
 * @dep: The endpoint to whom the request belongs to
 * @req: The request we're giving back
 * @status: completion code for the request
 *
 * Must be called with controller's lock held and interrupts disabled. This
 * function will unmap @req and call its ->complete() callback to notify upper
 * layers that it has completed.
 */
void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
                int status)
{
        struct dwc3                     *dwc = dep->dwc;

        dwc3_gadget_del_and_unmap_request(dep, req, status);

        spin_unlock(&dwc->lock);
        usb_gadget_giveback_request(&dep->endpoint, &req->request);
        spin_lock(&dwc->lock);
}

/**
 * dwc3_send_gadget_generic_command - issue a generic command for the controller
 * @dwc: pointer to the controller context
 * @cmd: the command to be issued
 * @param: command parameter
 *
 * Caller should take care of locking. Issue @cmd with a given @param to @dwc
 * and wait for its completion.
 */
int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned cmd, u32 param)
{
        u32             timeout = 500;
        int             status = 0;
        int             ret = 0;
        u32             reg;

        dwc3_writel(dwc->regs, DWC3_DGCMDPAR, param);
        dwc3_writel(dwc->regs, DWC3_DGCMD, cmd | DWC3_DGCMD_CMDACT);

        do {
                reg = dwc3_readl(dwc->regs, DWC3_DGCMD);
                if (!(reg & DWC3_DGCMD_CMDACT)) {
                        status = DWC3_DGCMD_STATUS(reg);
                        if (status)
                                ret = -EINVAL;
                        break;
                }
        } while (--timeout);

        if (!timeout) {
                ret = -ETIMEDOUT;
                status = -ETIMEDOUT;
        }

        trace_dwc3_gadget_generic_cmd(cmd, param, status);

        return ret;
}

static int __dwc3_gadget_wakeup(struct dwc3 *dwc);

/**
 * dwc3_send_gadget_ep_cmd - issue an endpoint command
 * @dep: the endpoint to which the command is going to be issued
 * @cmd: the command to be issued
 * @params: parameters to the command
 *
 * Caller should handle locking. This function will issue @cmd with given
 * @params to @dep and wait for its completion.
 */
int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned cmd,
                struct dwc3_gadget_ep_cmd_params *params)
{
        const struct usb_endpoint_descriptor *desc = dep->endpoint.desc;
        struct dwc3             *dwc = dep->dwc;
        u32                     timeout = 1000;
        u32                     reg;

        int                     cmd_status = 0;
        int                     susphy = false;
        int                     ret = -EINVAL;

        /*
         * Synopsys Databook 2.60a states, on section 6.3.2.5.[1-8], that if
         * we're issuing an endpoint command, we must check if
         * GUSB2PHYCFG.SUSPHY bit is set. If it is, then we need to clear it.
         *
         * We will also set SUSPHY bit to what it was before returning as stated
         * by the same section on Synopsys databook.
         */
        if (dwc->gadget.speed <= USB_SPEED_HIGH) {
                reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
                if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
                        susphy = true;
                        reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
                        dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
                }
        }

        if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
                int             needs_wakeup;

                needs_wakeup = (dwc->link_state == DWC3_LINK_STATE_U1 ||
                                dwc->link_state == DWC3_LINK_STATE_U2 ||
                                dwc->link_state == DWC3_LINK_STATE_U3);

                if (unlikely(needs_wakeup)) {
                        ret = __dwc3_gadget_wakeup(dwc);
                        dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
                                        ret);
                }
        }

        dwc3_writel(dep->regs, DWC3_DEPCMDPAR0, params->param0);
        dwc3_writel(dep->regs, DWC3_DEPCMDPAR1, params->param1);
        dwc3_writel(dep->regs, DWC3_DEPCMDPAR2, params->param2);

        /*
         * Synopsys Databook 2.60a states in section 6.3.2.5.6 of that if we're
         * not relying on XferNotReady, we can make use of a special "No
         * Response Update Transfer" command where we should clear both CmdAct
         * and CmdIOC bits.
         *
         * With this, we don't need to wait for command completion and can
         * straight away issue further commands to the endpoint.
         *
         * NOTICE: We're making an assumption that control endpoints will never
         * make use of Update Transfer command. This is a safe assumption
         * because we can never have more than one request at a time with
         * Control Endpoints. If anybody changes that assumption, this chunk
         * needs to be updated accordingly.
         */
        if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_UPDATETRANSFER &&
                        !usb_endpoint_xfer_isoc(desc))
                cmd &= ~(DWC3_DEPCMD_CMDIOC | DWC3_DEPCMD_CMDACT);
        else
                cmd |= DWC3_DEPCMD_CMDACT;

        dwc3_writel(dep->regs, DWC3_DEPCMD, cmd);
        do {
                reg = dwc3_readl(dep->regs, DWC3_DEPCMD);
                if (!(reg & DWC3_DEPCMD_CMDACT)) {
                        cmd_status = DWC3_DEPCMD_STATUS(reg);

                        switch (cmd_status) {
                        case 0:
                                ret = 0;
                                break;
                        case DEPEVT_TRANSFER_NO_RESOURCE:
                                ret = -EINVAL;
                                break;
                        case DEPEVT_TRANSFER_BUS_EXPIRY:
                                /*
                                 * SW issues START TRANSFER command to
                                 * isochronous ep with future frame interval. If
                                 * future interval time has already passed when
                                 * core receives the command, it will respond
                                 * with an error status of 'Bus Expiry'.
                                 *
                                 * Instead of always returning -EINVAL, let's
                                 * give a hint to the gadget driver that this is
                                 * the case by returning -EAGAIN.
                                 */
                                ret = -EAGAIN;
                                break;
                        default:
                                dev_WARN(dwc->dev, "UNKNOWN cmd status\n");
                        }

                        break;
                }
        } while (--timeout);

        if (timeout == 0) {
                ret = -ETIMEDOUT;
                cmd_status = -ETIMEDOUT;
        }

        trace_dwc3_gadget_ep_cmd(dep, cmd, params, cmd_status);

        if (ret == 0) {
                switch (DWC3_DEPCMD_CMD(cmd)) {
                case DWC3_DEPCMD_STARTTRANSFER:
                        dep->flags |= DWC3_EP_TRANSFER_STARTED;
                        break;
                case DWC3_DEPCMD_ENDTRANSFER:
                        dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
                        break;
                default:
                        /* nothing */
                        break;
                }
        }

        if (unlikely(susphy)) {
                reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
                reg |= DWC3_GUSB2PHYCFG_SUSPHY;
                dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
        }

        return ret;
}

static int dwc3_send_clear_stall_ep_cmd(struct dwc3_ep *dep)
{
        struct dwc3 *dwc = dep->dwc;
        struct dwc3_gadget_ep_cmd_params params;
        u32 cmd = DWC3_DEPCMD_CLEARSTALL;

        /*
         * As of core revision 2.60a the recommended programming model
         * is to set the ClearPendIN bit when issuing a Clear Stall EP
         * command for IN endpoints. This is to prevent an issue where
         * some (non-compliant) hosts may not send ACK TPs for pending
         * IN transfers due to a mishandled error condition. Synopsys
         * STAR 9000614252.
         */
        if (dep->direction && (dwc->revision >= DWC3_REVISION_260A) &&
            (dwc->gadget.speed >= USB_SPEED_SUPER))
                cmd |= DWC3_DEPCMD_CLEARPENDIN;

        memset(&params, 0, sizeof(params));

        return dwc3_send_gadget_ep_cmd(dep, cmd, &params);
}

static dma_addr_t dwc3_trb_dma_offset(struct dwc3_ep *dep,
                struct dwc3_trb *trb)
{
        u32             offset = (char *) trb - (char *) dep->trb_pool;

        return dep->trb_pool_dma + offset;
}

static int dwc3_alloc_trb_pool(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;

        if (dep->trb_pool)
                return 0;

        dep->trb_pool = dma_alloc_coherent(dwc->sysdev,
                        sizeof(struct dwc3_trb) * DWC3_TRB_NUM,
                        &dep->trb_pool_dma, GFP_KERNEL);
        if (!dep->trb_pool) {
                dev_err(dep->dwc->dev, "failed to allocate trb pool for %s\n",
                                dep->name);
                return -ENOMEM;
        }

        return 0;
}

static void dwc3_free_trb_pool(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;

        dma_free_coherent(dwc->sysdev, sizeof(struct dwc3_trb) * DWC3_TRB_NUM,
                        dep->trb_pool, dep->trb_pool_dma);

        dep->trb_pool = NULL;
        dep->trb_pool_dma = 0;
}

static int dwc3_gadget_set_xfer_resource(struct dwc3 *dwc, struct dwc3_ep *dep);

/**
 * dwc3_gadget_start_config - configure ep resources
 * @dwc: pointer to our controller context structure
 * @dep: endpoint that is being enabled
 *
 * Issue a %DWC3_DEPCMD_DEPSTARTCFG command to @dep. After the command's
 * completion, it will set Transfer Resource for all available endpoints.
 *
 * The assignment of transfer resources cannot perfectly follow the data book
 * due to the fact that the controller driver does not have all knowledge of the
 * configuration in advance. It is given this information piecemeal by the
 * composite gadget framework after every SET_CONFIGURATION and
 * SET_INTERFACE. Trying to follow the databook programming model in this
 * scenario can cause errors. For two reasons:
 *
 * 1) The databook says to do %DWC3_DEPCMD_DEPSTARTCFG for every
 * %USB_REQ_SET_CONFIGURATION and %USB_REQ_SET_INTERFACE (8.1.5). This is
 * incorrect in the scenario of multiple interfaces.
 *
 * 2) The databook does not mention doing more %DWC3_DEPCMD_DEPXFERCFG for new
 * endpoint on alt setting (8.1.6).
 *
 * The following simplified method is used instead:
 *
 * All hardware endpoints can be assigned a transfer resource and this setting
 * will stay persistent until either a core reset or hibernation. So whenever we
 * do a %DWC3_DEPCMD_DEPSTARTCFG(0) we can go ahead and do
 * %DWC3_DEPCMD_DEPXFERCFG for every hardware endpoint as well. We are
 * guaranteed that there are as many transfer resources as endpoints.
 *
 * This function is called for each endpoint when it is being enabled but is
 * triggered only when called for EP0-out, which always happens first, and which
 * should only happen in one of the above conditions.
 */
static int dwc3_gadget_start_config(struct dwc3 *dwc, struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;
        u32                     cmd;
        int                     i;
        int                     ret;

        if (dep->number)
                return 0;

        memset(&params, 0x00, sizeof(params));
        cmd = DWC3_DEPCMD_DEPSTARTCFG;

        ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
        if (ret)
                return ret;

        for (i = 0; i < DWC3_ENDPOINTS_NUM; i++) {
                struct dwc3_ep *dep = dwc->eps[i];

                if (!dep)
                        continue;

                ret = dwc3_gadget_set_xfer_resource(dwc, dep);
                if (ret)
                        return ret;
        }

        return 0;
}

static int dwc3_gadget_set_ep_config(struct dwc3 *dwc, struct dwc3_ep *dep,
                bool modify, bool restore)
{
        const struct usb_ss_ep_comp_descriptor *comp_desc;
        const struct usb_endpoint_descriptor *desc;
        struct dwc3_gadget_ep_cmd_params params;

        if (dev_WARN_ONCE(dwc->dev, modify && restore,
                                        "Can't modify and restore\n"))
                return -EINVAL;

        comp_desc = dep->endpoint.comp_desc;
        desc = dep->endpoint.desc;

        memset(&params, 0x00, sizeof(params));

        params.param0 = DWC3_DEPCFG_EP_TYPE(usb_endpoint_type(desc))
                | DWC3_DEPCFG_MAX_PACKET_SIZE(usb_endpoint_maxp(desc));

        /* Burst size is only needed in SuperSpeed mode */
        if (dwc->gadget.speed >= USB_SPEED_SUPER) {
                u32 burst = dep->endpoint.maxburst;
                params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst - 1);
        }

        if (modify) {
                params.param0 |= DWC3_DEPCFG_ACTION_MODIFY;
        } else if (restore) {
                params.param0 |= DWC3_DEPCFG_ACTION_RESTORE;
                params.param2 |= dep->saved_state;
        } else {
                params.param0 |= DWC3_DEPCFG_ACTION_INIT;
        }

        if (usb_endpoint_xfer_control(desc))
                params.param1 = DWC3_DEPCFG_XFER_COMPLETE_EN;

        if (dep->number <= 1 || usb_endpoint_xfer_isoc(desc))
                params.param1 |= DWC3_DEPCFG_XFER_NOT_READY_EN;

        if (usb_ss_max_streams(comp_desc) && usb_endpoint_xfer_bulk(desc)) {
                params.param1 |= DWC3_DEPCFG_STREAM_CAPABLE
                        | DWC3_DEPCFG_STREAM_EVENT_EN;
                dep->stream_capable = true;
        }

        if (!usb_endpoint_xfer_control(desc))
                params.param1 |= DWC3_DEPCFG_XFER_IN_PROGRESS_EN;

        /*
         * We are doing 1:1 mapping for endpoints, meaning
         * Physical Endpoints 2 maps to Logical Endpoint 2 and
         * so on. We consider the direction bit as part of the physical
         * endpoint number. So USB endpoint 0x81 is 0x03.
         */
        params.param1 |= DWC3_DEPCFG_EP_NUMBER(dep->number);

        /*
         * We must use the lower 16 TX FIFOs even though
         * HW might have more
         */
        if (dep->direction)
                params.param0 |= DWC3_DEPCFG_FIFO_NUMBER(dep->number >> 1);

        if (desc->bInterval) {
                params.param1 |= DWC3_DEPCFG_BINTERVAL_M1(desc->bInterval - 1);
                dep->interval = 1 << (desc->bInterval - 1);
        }

        return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETEPCONFIG, &params);
}

static int dwc3_gadget_set_xfer_resource(struct dwc3 *dwc, struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;

        memset(&params, 0x00, sizeof(params));

        params.param0 = DWC3_DEPXFERCFG_NUM_XFER_RES(1);

        return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETTRANSFRESOURCE,
                        &params);
}

/**
 * __dwc3_gadget_ep_enable - initializes a hw endpoint
 * @dep: endpoint to be initialized
 * @modify: if true, modify existing endpoint configuration
 * @restore: if true, restore endpoint configuration from scratch buffer
 *
 * Caller should take care of locking. Execute all necessary commands to
 * initialize a HW endpoint so it can be used by a gadget driver.
 */
static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep,
                bool modify, bool restore)
{
        const struct usb_endpoint_descriptor *desc = dep->endpoint.desc;
        struct dwc3             *dwc = dep->dwc;

        u32                     reg;
        int                     ret;

        if (!(dep->flags & DWC3_EP_ENABLED)) {
                ret = dwc3_gadget_start_config(dwc, dep);
                if (ret)
                        return ret;
        }

        ret = dwc3_gadget_set_ep_config(dwc, dep, modify, restore);
        if (ret)
                return ret;

        if (!(dep->flags & DWC3_EP_ENABLED)) {
                struct dwc3_trb *trb_st_hw;
                struct dwc3_trb *trb_link;

                dep->type = usb_endpoint_type(desc);
                dep->flags |= DWC3_EP_ENABLED;
                dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;

                reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
                reg |= DWC3_DALEPENA_EP(dep->number);
                dwc3_writel(dwc->regs, DWC3_DALEPENA, reg);

                init_waitqueue_head(&dep->wait_end_transfer);

                if (usb_endpoint_xfer_control(desc))
                        goto out;

                /* Initialize the TRB ring */
                dep->trb_dequeue = 0;
                dep->trb_enqueue = 0;
                memset(dep->trb_pool, 0,
                       sizeof(struct dwc3_trb) * DWC3_TRB_NUM);

                /* Link TRB. The HWO bit is never reset */
                trb_st_hw = &dep->trb_pool[0];

                trb_link = &dep->trb_pool[DWC3_TRB_NUM - 1];
                trb_link->bpl = lower_32_bits(dwc3_trb_dma_offset(dep, trb_st_hw));
                trb_link->bph = upper_32_bits(dwc3_trb_dma_offset(dep, trb_st_hw));
                trb_link->ctrl |= DWC3_TRBCTL_LINK_TRB;
                trb_link->ctrl |= DWC3_TRB_CTRL_HWO;
        }

        /*
         * Issue StartTransfer here with no-op TRB so we can always rely on No
         * Response Update Transfer command.
         */
        if (usb_endpoint_xfer_bulk(desc)) {
                struct dwc3_gadget_ep_cmd_params params;
                struct dwc3_trb *trb;
                dma_addr_t trb_dma;
                u32 cmd;

                memset(&params, 0, sizeof(params));
                trb = &dep->trb_pool[0];
                trb_dma = dwc3_trb_dma_offset(dep, trb);

                params.param0 = upper_32_bits(trb_dma);
                params.param1 = lower_32_bits(trb_dma);

                cmd = DWC3_DEPCMD_STARTTRANSFER;

                ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
                if (ret < 0)
                        return ret;

                dep->flags |= DWC3_EP_BUSY;

                dep->resource_index = dwc3_gadget_ep_get_transfer_index(dep);
                WARN_ON_ONCE(!dep->resource_index);
        }


out:
        trace_dwc3_gadget_ep_enable(dep);

        return 0;
}

static void dwc3_stop_active_transfer(struct dwc3 *dwc, u32 epnum, bool force);
static void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep)
{
        struct dwc3_request             *req;

        dwc3_stop_active_transfer(dwc, dep->number, true);

        /* - giveback all requests to gadget driver */
        while (!list_empty(&dep->started_list)) {
                req = next_request(&dep->started_list);

                dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
        }

        while (!list_empty(&dep->pending_list)) {
                req = next_request(&dep->pending_list);

                dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
        }
}

/**
 * __dwc3_gadget_ep_disable - disables a hw endpoint
 * @dep: the endpoint to disable
 *
 * This function undoes what __dwc3_gadget_ep_enable did and also removes
 * requests which are currently being processed by the hardware and those which
 * are not yet scheduled.
 *
 * Caller should take care of locking.
 */
static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;
        u32                     reg;

        trace_dwc3_gadget_ep_disable(dep);

        dwc3_remove_requests(dwc, dep);

        /* make sure HW endpoint isn't stalled */
        if (dep->flags & DWC3_EP_STALL)
                __dwc3_gadget_ep_set_halt(dep, 0, false);

        reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
        reg &= ~DWC3_DALEPENA_EP(dep->number);
        dwc3_writel(dwc->regs, DWC3_DALEPENA, reg);

        dep->stream_capable = false;
        dep->type = 0;
        dep->flags &= DWC3_EP_END_TRANSFER_PENDING;

        /* Clear out the ep descriptors for non-ep0 */
        if (dep->number > 1) {
                dep->endpoint.comp_desc = NULL;
                dep->endpoint.desc = NULL;
        }

        return 0;
}

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_ep0_enable(struct usb_ep *ep,
                const struct usb_endpoint_descriptor *desc)
{
        return -EINVAL;
}

static int dwc3_gadget_ep0_disable(struct usb_ep *ep)
{
        return -EINVAL;
}

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_ep_enable(struct usb_ep *ep,
                const struct usb_endpoint_descriptor *desc)
{
        struct dwc3_ep                  *dep;
        struct dwc3                     *dwc;
        unsigned long                   flags;
        int                             ret;

        if (!ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT) {
                pr_debug("dwc3: invalid parameters\n");
                return -EINVAL;
        }

        if (!desc->wMaxPacketSize) {
                pr_debug("dwc3: missing wMaxPacketSize\n");
                return -EINVAL;
        }

        dep = to_dwc3_ep(ep);
        dwc = dep->dwc;

        if (dev_WARN_ONCE(dwc->dev, dep->flags & DWC3_EP_ENABLED,
                                        "%s is already enabled\n",
                                        dep->name))
                return 0;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_enable(dep, false, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_ep_disable(struct usb_ep *ep)
{
        struct dwc3_ep                  *dep;
        struct dwc3                     *dwc;
        unsigned long                   flags;
        int                             ret;

        if (!ep) {
                pr_debug("dwc3: invalid parameters\n");
                return -EINVAL;
        }

        dep = to_dwc3_ep(ep);
        dwc = dep->dwc;

        if (dev_WARN_ONCE(dwc->dev, !(dep->flags & DWC3_EP_ENABLED),
                                        "%s is already disabled\n",
                                        dep->name))
                return 0;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_disable(dep);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static struct usb_request *dwc3_gadget_ep_alloc_request(struct usb_ep *ep,
        gfp_t gfp_flags)
{
        struct dwc3_request             *req;
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);

        req = kzalloc(sizeof(*req), gfp_flags);
        if (!req)
                return NULL;

        req->epnum      = dep->number;
        req->dep        = dep;

        dep->allocated_requests++;

        trace_dwc3_alloc_request(req);

        return &req->request;
}

static void dwc3_gadget_ep_free_request(struct usb_ep *ep,
                struct usb_request *request)
{
        struct dwc3_request             *req = to_dwc3_request(request);
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);

        dep->allocated_requests--;
        trace_dwc3_free_request(req);
        kfree(req);
}

static u32 dwc3_calc_trbs_left(struct dwc3_ep *dep);

static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb,
                dma_addr_t dma, unsigned length, unsigned chain, unsigned node,
                unsigned stream_id, unsigned short_not_ok, unsigned no_interrupt)
{
        struct dwc3             *dwc = dep->dwc;
        struct usb_gadget       *gadget = &dwc->gadget;
        enum usb_device_speed   speed = gadget->speed;

        dwc3_ep_inc_enq(dep);

        trb->size = DWC3_TRB_SIZE_LENGTH(length);
        trb->bpl = lower_32_bits(dma);
        trb->bph = upper_32_bits(dma);

        switch (usb_endpoint_type(dep->endpoint.desc)) {
        case USB_ENDPOINT_XFER_CONTROL:
                trb->ctrl = DWC3_TRBCTL_CONTROL_SETUP;
                break;

        case USB_ENDPOINT_XFER_ISOC:
                if (!node) {
                        trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS_FIRST;

                        /*
                         * USB Specification 2.0 Section 5.9.2 states that: "If
                         * there is only a single transaction in the microframe,
                         * only a DATA0 data packet PID is used.  If there are
                         * two transactions per microframe, DATA1 is used for
                         * the first transaction data packet and DATA0 is used
                         * for the second transaction data packet.  If there are
                         * three transactions per microframe, DATA2 is used for
                         * the first transaction data packet, DATA1 is used for
                         * the second, and DATA0 is used for the third."
                         *
                         * IOW, we should satisfy the following cases:
                         *
                         * 1) length <= maxpacket
                         *      - DATA0
                         *
                         * 2) maxpacket < length <= (2 * maxpacket)
                         *      - DATA1, DATA0
                         *
                         * 3) (2 * maxpacket) < length <= (3 * maxpacket)
                         *      - DATA2, DATA1, DATA0
                         */
                        if (speed == USB_SPEED_HIGH) {
                                struct usb_ep *ep = &dep->endpoint;
                                unsigned int mult = 2;
                                unsigned int maxp = usb_endpoint_maxp(ep->desc);

                                if (length <= (2 * maxp))
                                        mult--;

                                if (length <= maxp)
                                        mult--;

                                trb->size |= DWC3_TRB_SIZE_PCM1(mult);
                        }
                } else {
                        trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
                }

                /* always enable Interrupt on Missed ISOC */
                trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
                break;

        case USB_ENDPOINT_XFER_BULK:
        case USB_ENDPOINT_XFER_INT:
                trb->ctrl = DWC3_TRBCTL_NORMAL;
                break;
        default:
                /*
                 * This is only possible with faulty memory because we
                 * checked it already :)
                 */
                dev_WARN(dwc->dev, "Unknown endpoint type %d\n",
                                usb_endpoint_type(dep->endpoint.desc));
        }

        /* always enable Continue on Short Packet */
        if (usb_endpoint_dir_out(dep->endpoint.desc)) {
                trb->ctrl |= DWC3_TRB_CTRL_CSP;

                if (short_not_ok)
                        trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
        }

        if ((!no_interrupt && !chain) ||
                        (dwc3_calc_trbs_left(dep) == 0))
                trb->ctrl |= DWC3_TRB_CTRL_IOC;

        if (chain)
                trb->ctrl |= DWC3_TRB_CTRL_CHN;

        if (usb_endpoint_xfer_bulk(dep->endpoint.desc) && dep->stream_capable)
                trb->ctrl |= DWC3_TRB_CTRL_SID_SOFN(stream_id);

        trb->ctrl |= DWC3_TRB_CTRL_HWO;

        trace_dwc3_prepare_trb(dep, trb);
}

/**
 * dwc3_prepare_one_trb - setup one TRB from one request
 * @dep: endpoint for which this request is prepared
 * @req: dwc3_request pointer
 * @chain: should this TRB be chained to the next?
 * @node: only for isochronous endpoints. First TRB needs different type.
 */
static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
                struct dwc3_request *req, unsigned chain, unsigned node)
{
        struct dwc3_trb         *trb;
        unsigned                length = req->request.length;
        unsigned                stream_id = req->request.stream_id;
        unsigned                short_not_ok = req->request.short_not_ok;
        unsigned                no_interrupt = req->request.no_interrupt;
        dma_addr_t              dma = req->request.dma;

        trb = &dep->trb_pool[dep->trb_enqueue];

        if (!req->trb) {
                dwc3_gadget_move_started_request(req);
                req->trb = trb;
                req->trb_dma = dwc3_trb_dma_offset(dep, trb);
                dep->queued_requests++;
        }

        __dwc3_prepare_one_trb(dep, trb, dma, length, chain, node,
                        stream_id, short_not_ok, no_interrupt);
}

/**
 * dwc3_ep_prev_trb - returns the previous TRB in the ring
 * @dep: The endpoint with the TRB ring
 * @index: The index of the current TRB in the ring
 *
 * Returns the TRB prior to the one pointed to by the index. If the
 * index is 0, we will wrap backwards, skip the link TRB, and return
 * the one just before that.
 */
static struct dwc3_trb *dwc3_ep_prev_trb(struct dwc3_ep *dep, u8 index)
{
        u8 tmp = index;

        if (!tmp)
                tmp = DWC3_TRB_NUM - 1;

        return &dep->trb_pool[tmp - 1];
}

static u32 dwc3_calc_trbs_left(struct dwc3_ep *dep)
{
        struct dwc3_trb         *tmp;
        u8                      trbs_left;

        /*
         * If enqueue & dequeue are equal than it is either full or empty.
         *
         * One way to know for sure is if the TRB right before us has HWO bit
         * set or not. If it has, then we're definitely full and can't fit any
         * more transfers in our ring.
         */
        if (dep->trb_enqueue == dep->trb_dequeue) {
                tmp = dwc3_ep_prev_trb(dep, dep->trb_enqueue);
                if (tmp->ctrl & DWC3_TRB_CTRL_HWO)
                        return 0;

                return DWC3_TRB_NUM - 1;
        }

        trbs_left = dep->trb_dequeue - dep->trb_enqueue;
        trbs_left &= (DWC3_TRB_NUM - 1);

        if (dep->trb_dequeue < dep->trb_enqueue)
                trbs_left--;

        return trbs_left;
}

static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
                struct dwc3_request *req)
{
        struct scatterlist *sg = req->sg;
        struct scatterlist *s;
        int             i;

        for_each_sg(sg, s, req->num_pending_sgs, i) {
                unsigned int length = req->request.length;
                unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
                unsigned int rem = length % maxp;
                unsigned chain = true;

                if (sg_is_last(s))
                        chain = false;

                if (rem && usb_endpoint_dir_out(dep->endpoint.desc) && !chain) {
                        struct dwc3     *dwc = dep->dwc;
                        struct dwc3_trb *trb;

                        req->unaligned = true;

                        /* prepare normal TRB */
                        dwc3_prepare_one_trb(dep, req, true, i);

                        /* Now prepare one extra TRB to align transfer size */
                        trb = &dep->trb_pool[dep->trb_enqueue];
                        __dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr,
                                        maxp - rem, false, 0,
                                        req->request.stream_id,
                                        req->request.short_not_ok,
                                        req->request.no_interrupt);
                } else {
                        dwc3_prepare_one_trb(dep, req, chain, i);
                }

                if (!dwc3_calc_trbs_left(dep))
                        break;
        }
}

static void dwc3_prepare_one_trb_linear(struct dwc3_ep *dep,
                struct dwc3_request *req)
{
        unsigned int length = req->request.length;
        unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
        unsigned int rem = length % maxp;

        if (rem && usb_endpoint_dir_out(dep->endpoint.desc)) {
                struct dwc3     *dwc = dep->dwc;
                struct dwc3_trb *trb;

                req->unaligned = true;

                /* prepare normal TRB */
                dwc3_prepare_one_trb(dep, req, true, 0);

                /* Now prepare one extra TRB to align transfer size */
                trb = &dep->trb_pool[dep->trb_enqueue];
                __dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr, maxp - rem,
                                false, 0, req->request.stream_id,
                                req->request.short_not_ok,
                                req->request.no_interrupt);
        } else if (req->request.zero && req->request.length &&
                   (IS_ALIGNED(req->request.length,dep->endpoint.maxpacket))) {
                struct dwc3     *dwc = dep->dwc;
                struct dwc3_trb *trb;

                req->zero = true;

                /* prepare normal TRB */
                dwc3_prepare_one_trb(dep, req, true, 0);

                /* Now prepare one extra TRB to handle ZLP */
                trb = &dep->trb_pool[dep->trb_enqueue];
                __dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr, 0,
                                false, 0, req->request.stream_id,
                                req->request.short_not_ok,
                                req->request.no_interrupt);
        } else {
                dwc3_prepare_one_trb(dep, req, false, 0);
        }
}

/*
 * dwc3_prepare_trbs - setup TRBs from requests
 * @dep: endpoint for which requests are being prepared
 *
 * The function goes through the requests list and sets up TRBs for the
 * transfers. The function returns once there are no more TRBs available or
 * it runs out of requests.
 */
static void dwc3_prepare_trbs(struct dwc3_ep *dep)
{
        struct dwc3_request     *req, *n;

        BUILD_BUG_ON_NOT_POWER_OF_2(DWC3_TRB_NUM);

        /*
         * We can get in a situation where there's a request in the started list
         * but there weren't enough TRBs to fully kick it in the first time
         * around, so it has been waiting for more TRBs to be freed up.
         *
         * In that case, we should check if we have a request with pending_sgs
         * in the started list and prepare TRBs for that request first,
         * otherwise we will prepare TRBs completely out of order and that will
         * break things.
         */
        list_for_each_entry(req, &dep->started_list, list) {
                if (req->num_pending_sgs > 0)
                        dwc3_prepare_one_trb_sg(dep, req);

                if (!dwc3_calc_trbs_left(dep))
                        return;
        }

        list_for_each_entry_safe(req, n, &dep->pending_list, list) {
                struct dwc3     *dwc = dep->dwc;
                int             ret;

                ret = usb_gadget_map_request_by_dev(dwc->sysdev, &req->request,
                                                    dep->direction);
                if (ret)
                        return;

                req->sg                 = req->request.sg;
                req->num_pending_sgs    = req->request.num_mapped_sgs;

                if (req->num_pending_sgs > 0)
                        dwc3_prepare_one_trb_sg(dep, req);
                else
                        dwc3_prepare_one_trb_linear(dep, req);

                if (!dwc3_calc_trbs_left(dep))
                        return;
        }
}

static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;
        struct dwc3_request             *req;
        int                             starting;
        int                             ret;
        u32                             cmd;

        if (!dwc3_calc_trbs_left(dep))
                return 0;

        starting = !(dep->flags & DWC3_EP_BUSY);

        dwc3_prepare_trbs(dep);
        req = next_request(&dep->started_list);
        if (!req) {
                dep->flags |= DWC3_EP_PENDING_REQUEST;
                return 0;
        }

        memset(&params, 0, sizeof(params));

        if (starting) {
                params.param0 = upper_32_bits(req->trb_dma);
                params.param1 = lower_32_bits(req->trb_dma);
                cmd = DWC3_DEPCMD_STARTTRANSFER;

                if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
                        cmd |= DWC3_DEPCMD_PARAM(dep->frame_number);
        } else {
                cmd = DWC3_DEPCMD_UPDATETRANSFER |
                        DWC3_DEPCMD_PARAM(dep->resource_index);
        }

        ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
        if (ret < 0) {
                /*
                 * FIXME we need to iterate over the list of requests
                 * here and stop, unmap, free and del each of the linked
                 * requests instead of what we do now.
                 */
                if (req->trb)
                        memset(req->trb, 0, sizeof(struct dwc3_trb));
                dep->queued_requests--;
                dwc3_gadget_del_and_unmap_request(dep, req, ret);
                return ret;
        }

        dep->flags |= DWC3_EP_BUSY;

        if (starting) {
                dep->resource_index = dwc3_gadget_ep_get_transfer_index(dep);
                WARN_ON_ONCE(!dep->resource_index);
        }

        return 0;
}

static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
{
        u32                     reg;

        reg = dwc3_readl(dwc->regs, DWC3_DSTS);
        return DWC3_DSTS_SOFFN(reg);
}

static void __dwc3_gadget_start_isoc(struct dwc3 *dwc,
                struct dwc3_ep *dep, u32 cur_uf)
{
        if (list_empty(&dep->pending_list)) {
                dev_info(dwc->dev, "%s: ran out of requests\n",
                                dep->name);
                dep->flags |= DWC3_EP_PENDING_REQUEST;
                return;
        }

        /*
         * Schedule the first trb for one interval in the future or at
         * least 4 microframes.
         */
        dep->frame_number = cur_uf + max_t(u32, 4, dep->interval);
        __dwc3_gadget_kick_transfer(dep);
}

static void dwc3_gadget_start_isoc(struct dwc3 *dwc,
                struct dwc3_ep *dep, const struct dwc3_event_depevt *event)
{
        u32 cur_uf, mask;

        mask = ~(dep->interval - 1);
        cur_uf = event->parameters & mask;

        __dwc3_gadget_start_isoc(dwc, dep, cur_uf);
}

static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
{
        struct dwc3             *dwc = dep->dwc;

        if (!dep->endpoint.desc) {
                dev_err(dwc->dev, "%s: can't queue to disabled endpoint\n",
                                dep->name);
                return -ESHUTDOWN;
        }

        if (WARN(req->dep != dep, "request %pK belongs to '%s'\n",
                                &req->request, req->dep->name))
                return -EINVAL;

        pm_runtime_get(dwc->dev);

        req->request.actual     = 0;
        req->request.status     = -EINPROGRESS;
        req->direction          = dep->direction;
        req->epnum              = dep->number;

        trace_dwc3_ep_queue(req);

        list_add_tail(&req->list, &dep->pending_list);

        /*
         * NOTICE: Isochronous endpoints should NEVER be prestarted. We must
         * wait for a XferNotReady event so we will know what's the current
         * (micro-)frame number.
         *
         * Without this trick, we are very, very likely gonna get Bus Expiry
         * errors which will force us issue EndTransfer command.
         */
        if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
                if ((dep->flags & DWC3_EP_PENDING_REQUEST)) {
                        if (dep->flags & DWC3_EP_TRANSFER_STARTED) {
                                dwc3_stop_active_transfer(dwc, dep->number, true);
                                dep->flags = DWC3_EP_ENABLED;
                        } else {
                                u32 cur_uf;

                                cur_uf = __dwc3_gadget_get_frame(dwc);
                                __dwc3_gadget_start_isoc(dwc, dep, cur_uf);
                                dep->flags &= ~DWC3_EP_PENDING_REQUEST;
                        }
                        return 0;
                }

                if ((dep->flags & DWC3_EP_BUSY) &&
                    !(dep->flags & DWC3_EP_MISSED_ISOC))
                        goto out;

                return 0;
        }

out:
        return __dwc3_gadget_kick_transfer(dep);
}

static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
        gfp_t gfp_flags)
{
        struct dwc3_request             *req = to_dwc3_request(request);
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;

        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_queue(dep, req);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
                struct usb_request *request)
{
        struct dwc3_request             *req = to_dwc3_request(request);
        struct dwc3_request             *r = NULL;

        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;
        int                             ret = 0;

        trace_dwc3_ep_dequeue(req);

        spin_lock_irqsave(&dwc->lock, flags);

        list_for_each_entry(r, &dep->pending_list, list) {
                if (r == req)
                        break;
        }

        if (r != req) {
                list_for_each_entry(r, &dep->started_list, list) {
                        if (r == req)
                                break;
                }
                if (r == req) {
                        /* wait until it is processed */
                        dwc3_stop_active_transfer(dwc, dep->number, true);

                        /*
                         * If request was already started, this means we had to
                         * stop the transfer. With that we also need to ignore
                         * all TRBs used by the request, however TRBs can only
                         * be modified after completion of END_TRANSFER
                         * command. So what we do here is that we wait for
                         * END_TRANSFER completion and only after that, we jump
                         * over TRBs by clearing HWO and incrementing dequeue
                         * pointer.
                         *
                         * Note that we have 2 possible types of transfers here:
                         *
                         * i) Linear buffer request
                         * ii) SG-list based request
                         *
                         * SG-list based requests will have r->num_pending_sgs
                         * set to a valid number (> 0). Linear requests,
                         * normally use a single TRB.
                         *
                         * For each of these two cases, if r->unaligned flag is
                         * set, one extra TRB has been used to align transfer
                         * size to wMaxPacketSize.
                         *
                         * All of these cases need to be taken into
                         * consideration so we don't mess up our TRB ring
                         * pointers.
                         */
                        wait_event_lock_irq(dep->wait_end_transfer,
                                        !(dep->flags & DWC3_EP_END_TRANSFER_PENDING),
                                        dwc->lock);

                        if (!r->trb)
                                goto out1;

                        if (r->num_pending_sgs) {
                                struct dwc3_trb *trb;
                                int i = 0;

                                for (i = 0; i < r->num_pending_sgs; i++) {
                                        trb = r->trb + i;
                                        trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                                        dwc3_ep_inc_deq(dep);
                                }

                                if (r->unaligned || r->zero) {
                                        trb = r->trb + r->num_pending_sgs + 1;
                                        trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                                        dwc3_ep_inc_deq(dep);
                                }
                        } else {
                                struct dwc3_trb *trb = r->trb;

                                trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                                dwc3_ep_inc_deq(dep);

                                if (r->unaligned || r->zero) {
                                        trb = r->trb + 1;
                                        trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                                        dwc3_ep_inc_deq(dep);
                                }
                        }
                        goto out1;
                }
                dev_err(dwc->dev, "request %pK was not queued to %s\n",
                                request, ep->name);
                ret = -EINVAL;
                goto out0;
        }

out1:
        /* giveback the request */
        dep->queued_requests--;
        dwc3_gadget_giveback(dep, req, -ECONNRESET);

out0:
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
{
        struct dwc3_gadget_ep_cmd_params        params;
        struct dwc3                             *dwc = dep->dwc;
        int                                     ret;

        if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
                dev_err(dwc->dev, "%s is of Isochronous type\n", dep->name);
                return -EINVAL;
        }

        memset(&params, 0x00, sizeof(params));

        if (value) {
                struct dwc3_trb *trb;

                unsigned transfer_in_flight;
                unsigned started;

                if (dep->flags & DWC3_EP_STALL)
                        return 0;

                if (dep->number > 1)
                        trb = dwc3_ep_prev_trb(dep, dep->trb_enqueue);
                else
                        trb = &dwc->ep0_trb[dep->trb_enqueue];

                transfer_in_flight = trb->ctrl & DWC3_TRB_CTRL_HWO;
                started = !list_empty(&dep->started_list);

                if (!protocol && ((dep->direction && transfer_in_flight) ||
                                (!dep->direction && started))) {
                        return -EAGAIN;
                }

                ret = dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETSTALL,
                                &params);
                if (ret)
                        dev_err(dwc->dev, "failed to set STALL on %s\n",
                                        dep->name);
                else
                        dep->flags |= DWC3_EP_STALL;
        } else {
                if (!(dep->flags & DWC3_EP_STALL))
                        return 0;

                ret = dwc3_send_clear_stall_ep_cmd(dep);
                if (ret)
                        dev_err(dwc->dev, "failed to clear STALL on %s\n",
                                        dep->name);
                else
                        dep->flags &= ~(DWC3_EP_STALL | DWC3_EP_WEDGE);
        }

        return ret;
}

static int dwc3_gadget_ep_set_halt(struct usb_ep *ep, int value)
{
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;

        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_set_halt(dep, value, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_ep_set_wedge(struct usb_ep *ep)
{
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;
        unsigned long                   flags;
        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        dep->flags |= DWC3_EP_WEDGE;

        if (dep->number == 0 || dep->number == 1)
                ret = __dwc3_gadget_ep0_set_halt(ep, 1);
        else
                ret = __dwc3_gadget_ep_set_halt(dep, 1, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

/* -------------------------------------------------------------------------- */

static struct usb_endpoint_descriptor dwc3_gadget_ep0_desc = {
        .bLength        = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,
        .bmAttributes   = USB_ENDPOINT_XFER_CONTROL,
};

static const struct usb_ep_ops dwc3_gadget_ep0_ops = {
        .enable         = dwc3_gadget_ep0_enable,
        .disable        = dwc3_gadget_ep0_disable,
        .alloc_request  = dwc3_gadget_ep_alloc_request,
        .free_request   = dwc3_gadget_ep_free_request,
        .queue          = dwc3_gadget_ep0_queue,
        .dequeue        = dwc3_gadget_ep_dequeue,
        .set_halt       = dwc3_gadget_ep0_set_halt,
        .set_wedge      = dwc3_gadget_ep_set_wedge,
};

static const struct usb_ep_ops dwc3_gadget_ep_ops = {
        .enable         = dwc3_gadget_ep_enable,
        .disable        = dwc3_gadget_ep_disable,
        .alloc_request  = dwc3_gadget_ep_alloc_request,
        .free_request   = dwc3_gadget_ep_free_request,
        .queue          = dwc3_gadget_ep_queue,
        .dequeue        = dwc3_gadget_ep_dequeue,
        .set_halt       = dwc3_gadget_ep_set_halt,
        .set_wedge      = dwc3_gadget_ep_set_wedge,
};

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_get_frame(struct usb_gadget *g)
{
        struct dwc3             *dwc = gadget_to_dwc(g);

        return __dwc3_gadget_get_frame(dwc);
}

static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
{
        int                     retries;

        int                     ret;
        u32                     reg;

        u8                      link_state;
        u8                      speed;

        /*
         * According to the Databook Remote wakeup request should
         * be issued only when the device is in early suspend state.
         *
         * We can check that via USB Link State bits in DSTS register.
         */
        reg = dwc3_readl(dwc->regs, DWC3_DSTS);

        speed = reg & DWC3_DSTS_CONNECTSPD;
        if ((speed == DWC3_DSTS_SUPERSPEED) ||
            (speed == DWC3_DSTS_SUPERSPEED_PLUS))
                return 0;

        link_state = DWC3_DSTS_USBLNKST(reg);

        switch (link_state) {
        case DWC3_LINK_STATE_RX_DET:    /* in HS, means Early Suspend */
        case DWC3_LINK_STATE_U3:        /* in HS, means SUSPEND */
                break;
        default:
                return -EINVAL;
        }

        ret = dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RECOV);
        if (ret < 0) {
                dev_err(dwc->dev, "failed to put link in Recovery\n");
                return ret;
        }

        /* Recent versions do this automatically */
        if (dwc->revision < DWC3_REVISION_194A) {
                /* write zeroes to Link Change Request */
                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        }

        /* poll until Link State changes to ON */
        retries = 20000;

        while (retries--) {
                reg = dwc3_readl(dwc->regs, DWC3_DSTS);

                /* in HS, means ON */
                if (DWC3_DSTS_USBLNKST(reg) == DWC3_LINK_STATE_U0)
                        break;
        }

        if (DWC3_DSTS_USBLNKST(reg) != DWC3_LINK_STATE_U0) {
                dev_err(dwc->dev, "failed to send remote wakeup\n");
                return -EINVAL;
        }

        return 0;
}

static int dwc3_gadget_wakeup(struct usb_gadget *g)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_wakeup(dwc);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
                int is_selfpowered)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;

        spin_lock_irqsave(&dwc->lock, flags);
        g->is_selfpowered = !!is_selfpowered;
        spin_unlock_irqrestore(&dwc->lock, flags);

        return 0;
}

static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
{
        u32                     reg;
        u32                     timeout = 500;

        if (pm_runtime_suspended(dwc->dev))
                return 0;

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        if (is_on) {
                if (dwc->revision <= DWC3_REVISION_187A) {
                        reg &= ~DWC3_DCTL_TRGTULST_MASK;
                        reg |= DWC3_DCTL_TRGTULST_RX_DET;
                }

                if (dwc->revision >= DWC3_REVISION_194A)
                        reg &= ~DWC3_DCTL_KEEP_CONNECT;
                reg |= DWC3_DCTL_RUN_STOP;

                if (dwc->has_hibernation)
                        reg |= DWC3_DCTL_KEEP_CONNECT;

                dwc->pullups_connected = true;
        } else {
                reg &= ~DWC3_DCTL_RUN_STOP;

                if (dwc->has_hibernation && !suspend)
                        reg &= ~DWC3_DCTL_KEEP_CONNECT;

                dwc->pullups_connected = false;
        }

        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        do {
                reg = dwc3_readl(dwc->regs, DWC3_DSTS);
                reg &= DWC3_DSTS_DEVCTRLHLT;
        } while (--timeout && !(!is_on ^ !reg));

        if (!timeout)
                return -ETIMEDOUT;

        return 0;
}

static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     ret;

        is_on = !!is_on;

        /*
         * Per databook, when we want to stop the gadget, if a control transfer
         * is still in process, complete it and get the core into setup phase.
         */
        if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {
                reinit_completion(&dwc->ep0_in_setup);

                ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
                                msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
                if (ret == 0) {
                        dev_err(dwc->dev, "timed out waiting for SETUP phase\n");
                        return -ETIMEDOUT;
                }
        }

        spin_lock_irqsave(&dwc->lock, flags);
        ret = dwc3_gadget_run_stop(dwc, is_on, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static void dwc3_gadget_enable_irq(struct dwc3 *dwc)
{
        u32                     reg;

        /* Enable all but Start and End of Frame IRQs */
        reg = (DWC3_DEVTEN_VNDRDEVTSTRCVEDEN |
                        DWC3_DEVTEN_EVNTOVERFLOWEN |
                        DWC3_DEVTEN_CMDCMPLTEN |
                        DWC3_DEVTEN_ERRTICERREN |
                        DWC3_DEVTEN_WKUPEVTEN |
                        DWC3_DEVTEN_CONNECTDONEEN |
                        DWC3_DEVTEN_USBRSTEN |
                        DWC3_DEVTEN_DISCONNEVTEN);

        if (dwc->revision < DWC3_REVISION_250A)
                reg |= DWC3_DEVTEN_ULSTCNGEN;

        dwc3_writel(dwc->regs, DWC3_DEVTEN, reg);
}

static void dwc3_gadget_disable_irq(struct dwc3 *dwc)
{
        /* mask all interrupts */
        dwc3_writel(dwc->regs, DWC3_DEVTEN, 0x00);
}

static irqreturn_t dwc3_interrupt(int irq, void *_dwc);
static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc);

/**
 * dwc3_gadget_setup_nump - calculate and initialize NUMP field of %DWC3_DCFG
 * @dwc: pointer to our context structure
 *
 * The following looks like complex but it's actually very simple. In order to
 * calculate the number of packets we can burst at once on OUT transfers, we're
 * gonna use RxFIFO size.
 *
 * To calculate RxFIFO size we need two numbers:
 * MDWIDTH = size, in bits, of the internal memory bus
 * RAM2_DEPTH = depth, in MDWIDTH, of internal RAM2 (where RxFIFO sits)
 *
 * Given these two numbers, the formula is simple:
 *
 * RxFIFO Size = (RAM2_DEPTH * MDWIDTH / 8) - 24 - 16;
 *
 * 24 bytes is for 3x SETUP packets
 * 16 bytes is a clock domain crossing tolerance
 *
 * Given RxFIFO Size, NUMP = RxFIFOSize / 1024;
 */
static void dwc3_gadget_setup_nump(struct dwc3 *dwc)
{
        u32 ram2_depth;
        u32 mdwidth;
        u32 nump;
        u32 reg;

        ram2_depth = DWC3_GHWPARAMS7_RAM2_DEPTH(dwc->hwparams.hwparams7);
        mdwidth = DWC3_GHWPARAMS0_MDWIDTH(dwc->hwparams.hwparams0);

        nump = ((ram2_depth * mdwidth / 8) - 24 - 16) / 1024;
        nump = min_t(u32, nump, 16);

        /* update NumP */
        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~DWC3_DCFG_NUMP_MASK;
        reg |= nump << DWC3_DCFG_NUMP_SHIFT;
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);
}

static int __dwc3_gadget_start(struct dwc3 *dwc)
{
        struct dwc3_ep          *dep;
        int                     ret = 0;
        u32                     reg;

        /*
         * Use IMOD if enabled via dwc->imod_interval. Otherwise, if
         * the core supports IMOD, disable it.
         */
        if (dwc->imod_interval) {
                dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval);
                dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB);
        } else if (dwc3_has_imod(dwc)) {
                dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), 0);
        }

        /*
         * We are telling dwc3 that we want to use DCFG.NUMP as ACK TP's NUMP
         * field instead of letting dwc3 itself calculate that automatically.
         *
         * This way, we maximize the chances that we'll be able to get several
         * bursts of data without going through any sort of endpoint throttling.
         */
        reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
        if (dwc3_is_usb31(dwc))
                reg &= ~DWC31_GRXTHRCFG_PKTCNTSEL;
        else
                reg &= ~DWC3_GRXTHRCFG_PKTCNTSEL;

        dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);

        dwc3_gadget_setup_nump(dwc);

        /* Start with SuperSpeed Default */
        dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);

        dep = dwc->eps[0];
        ret = __dwc3_gadget_ep_enable(dep, false, false);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                goto err0;
        }

        dep = dwc->eps[1];
        ret = __dwc3_gadget_ep_enable(dep, false, false);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                goto err1;
        }

        /* begin to receive SETUP packets */
        dwc->ep0state = EP0_SETUP_PHASE;
        dwc3_ep0_out_start(dwc);

        dwc3_gadget_enable_irq(dwc);

        return 0;

err1:
        __dwc3_gadget_ep_disable(dwc->eps[0]);

err0:
        return ret;
}

static int dwc3_gadget_start(struct usb_gadget *g,
                struct usb_gadget_driver *driver)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     ret = 0;
        int                     irq;

        irq = dwc->irq_gadget;
        ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
                        IRQF_SHARED, "dwc3", dwc->ev_buf);
        if (ret) {
                dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
                                irq, ret);
                goto err0;
        }

        spin_lock_irqsave(&dwc->lock, flags);
        if (dwc->gadget_driver) {
                dev_err(dwc->dev, "%s is already bound to %s\n",
                                dwc->gadget.name,
                                dwc->gadget_driver->driver.name);
                ret = -EBUSY;
                goto err1;
        }

        dwc->gadget_driver      = driver;

        if (pm_runtime_active(dwc->dev))
                __dwc3_gadget_start(dwc);

        spin_unlock_irqrestore(&dwc->lock, flags);

        return 0;

err1:
        spin_unlock_irqrestore(&dwc->lock, flags);
        free_irq(irq, dwc);

err0:
        return ret;
}

static void __dwc3_gadget_stop(struct dwc3 *dwc)
{
        dwc3_gadget_disable_irq(dwc);
        __dwc3_gadget_ep_disable(dwc->eps[0]);
        __dwc3_gadget_ep_disable(dwc->eps[1]);
}

static int dwc3_gadget_stop(struct usb_gadget *g)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     epnum;
        u32                     tmo_eps = 0;

        spin_lock_irqsave(&dwc->lock, flags);

        if (pm_runtime_suspended(dwc->dev))
                goto out;

        __dwc3_gadget_stop(dwc);

        for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
                struct dwc3_ep  *dep = dwc->eps[epnum];
                int ret;

                if (!dep)
                        continue;

                if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
                        continue;

                ret = wait_event_interruptible_lock_irq_timeout(dep->wait_end_transfer,
                            !(dep->flags & DWC3_EP_END_TRANSFER_PENDING),
                            dwc->lock, msecs_to_jiffies(5));

                if (ret <= 0) {
                        /* Timed out or interrupted! There's nothing much
                         * we can do so we just log here and print which
                         * endpoints timed out at the end.
                         */
                        tmo_eps |= 1 << epnum;
                        dep->flags &= DWC3_EP_END_TRANSFER_PENDING;
                }
        }

        if (tmo_eps) {
                dev_err(dwc->dev,
                        "end transfer timed out on endpoints 0x%x [bitmap]\n",
                        tmo_eps);
        }

out:
        dwc->gadget_driver      = NULL;
        spin_unlock_irqrestore(&dwc->lock, flags);

        free_irq(dwc->irq_gadget, dwc->ev_buf);

        return 0;
}

static void dwc3_gadget_set_speed(struct usb_gadget *g,
                                  enum usb_device_speed speed)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        u32                     reg;

        spin_lock_irqsave(&dwc->lock, flags);
        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~(DWC3_DCFG_SPEED_MASK);

        /*
         * WORKAROUND: DWC3 revision < 2.20a have an issue
         * which would cause metastability state on Run/Stop
         * bit if we try to force the IP to USB2-only mode.
         *
         * Because of that, we cannot configure the IP to any
         * speed other than the SuperSpeed
         *
         * Refers to:
         *
         * STAR#9000525659: Clock Domain Crossing on DCTL in
         * USB 2.0 Mode
         */
        if (dwc->revision < DWC3_REVISION_220A &&
            !dwc->dis_metastability_quirk) {
                reg |= DWC3_DCFG_SUPERSPEED;
        } else {
                switch (speed) {
                case USB_SPEED_LOW:
                        reg |= DWC3_DCFG_LOWSPEED;
                        break;
                case USB_SPEED_FULL:
                        reg |= DWC3_DCFG_FULLSPEED;
                        break;
                case USB_SPEED_HIGH:
                        reg |= DWC3_DCFG_HIGHSPEED;
                        break;
                case USB_SPEED_SUPER:
                        reg |= DWC3_DCFG_SUPERSPEED;
                        break;
                case USB_SPEED_SUPER_PLUS:
                        if (dwc3_is_usb31(dwc))
                                reg |= DWC3_DCFG_SUPERSPEED_PLUS;
                        else
                                reg |= DWC3_DCFG_SUPERSPEED;
                        break;
                default:
                        dev_err(dwc->dev, "invalid speed (%d)\n", speed);

                        if (dwc->revision & DWC3_REVISION_IS_DWC31)
                                reg |= DWC3_DCFG_SUPERSPEED_PLUS;
                        else
                                reg |= DWC3_DCFG_SUPERSPEED;
                }
        }
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);

        spin_unlock_irqrestore(&dwc->lock, flags);
}

static const struct usb_gadget_ops dwc3_gadget_ops = {
        .get_frame              = dwc3_gadget_get_frame,
        .wakeup                 = dwc3_gadget_wakeup,
        .set_selfpowered        = dwc3_gadget_set_selfpowered,
        .pullup                 = dwc3_gadget_pullup,
        .udc_start              = dwc3_gadget_start,
        .udc_stop               = dwc3_gadget_stop,
        .udc_set_speed          = dwc3_gadget_set_speed,
};

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_init_endpoints(struct dwc3 *dwc, u8 total)
{
        struct dwc3_ep                  *dep;
        u8                              epnum;

        INIT_LIST_HEAD(&dwc->gadget.ep_list);

        for (epnum = 0; epnum < total; epnum++) {
                bool                    direction = epnum & 1;
                u8                      num = epnum >> 1;

                dep = kzalloc(sizeof(*dep), GFP_KERNEL);
                if (!dep)
                        return -ENOMEM;

                dep->dwc = dwc;
                dep->number = epnum;
                dep->direction = direction;
                dep->regs = dwc->regs + DWC3_DEP_BASE(epnum);
                dwc->eps[epnum] = dep;

                snprintf(dep->name, sizeof(dep->name), "ep%u%s", num,
                                direction ? "in" : "out");

                dep->endpoint.name = dep->name;

                if (!(dep->number > 1)) {
                        dep->endpoint.desc = &dwc3_gadget_ep0_desc;
                        dep->endpoint.comp_desc = NULL;
                }

                spin_lock_init(&dep->lock);

                if (num == 0) {
                        usb_ep_set_maxpacket_limit(&dep->endpoint, 512);
                        dep->endpoint.maxburst = 1;
                        dep->endpoint.ops = &dwc3_gadget_ep0_ops;
                        if (!direction)
                                dwc->gadget.ep0 = &dep->endpoint;
                } else if (direction) {
                        int mdwidth;
                        int kbytes;
                        int size;
                        int ret;

                        mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
                        /* MDWIDTH is represented in bits, we need it in bytes */
                        mdwidth /= 8;

                        size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num));
                        if (dwc3_is_usb31(dwc))
                                size = DWC31_GTXFIFOSIZ_TXFDEF(size);
                        else
                                size = DWC3_GTXFIFOSIZ_TXFDEF(size);

                        /* FIFO Depth is in MDWDITH bytes. Multiply */
                        size *= mdwidth;

                        kbytes = size / 1024;
                        if (kbytes == 0)
                                kbytes = 1;

                        /*
                         * FIFO sizes account an extra MDWIDTH * (kbytes + 1) bytes for
                         * internal overhead. We don't really know how these are used,
                         * but documentation say it exists.
                         */
                        size -= mdwidth * (kbytes + 1);
                        size /= kbytes;

                        usb_ep_set_maxpacket_limit(&dep->endpoint, size);

                        dep->endpoint.max_streams = 15;
                        dep->endpoint.ops = &dwc3_gadget_ep_ops;
                        list_add_tail(&dep->endpoint.ep_list,
                                        &dwc->gadget.ep_list);

                        ret = dwc3_alloc_trb_pool(dep);
                        if (ret)
                                return ret;
                } else {
                        int             ret;

                        usb_ep_set_maxpacket_limit(&dep->endpoint, 1024);
                        dep->endpoint.max_streams = 15;
                        dep->endpoint.ops = &dwc3_gadget_ep_ops;
                        list_add_tail(&dep->endpoint.ep_list,
                                        &dwc->gadget.ep_list);

                        ret = dwc3_alloc_trb_pool(dep);
                        if (ret)
                                return ret;
                }

                if (num == 0) {
                        dep->endpoint.caps.type_control = true;
                } else {
                        dep->endpoint.caps.type_iso = true;
                        dep->endpoint.caps.type_bulk = true;
                        dep->endpoint.caps.type_int = true;
                }

                dep->endpoint.caps.dir_in = direction;
                dep->endpoint.caps.dir_out = !direction;

                INIT_LIST_HEAD(&dep->pending_list);
                INIT_LIST_HEAD(&dep->started_list);
        }

        return 0;
}

static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
{
        struct dwc3_ep                  *dep;
        u8                              epnum;

        for (epnum = 0; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
                dep = dwc->eps[epnum];
                if (!dep)
                        continue;
                /*
                 * Physical endpoints 0 and 1 are special; they form the
                 * bi-directional USB endpoint 0.
                 *
                 * For those two physical endpoints, we don't allocate a TRB
                 * pool nor do we add them the endpoints list. Due to that, we
                 * shouldn't do these two operations otherwise we would end up
                 * with all sorts of bugs when removing dwc3.ko.
                 */
                if (epnum != 0 && epnum != 1) {
                        dwc3_free_trb_pool(dep);
                        list_del(&dep->endpoint.ep_list);
                }

                kfree(dep);
        }
}

/* -------------------------------------------------------------------------- */

static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
                struct dwc3_request *req, struct dwc3_trb *trb,
                const struct dwc3_event_depevt *event, int status,
                int chain)
{
        unsigned int            count;
        unsigned int            s_pkt = 0;
        unsigned int            trb_status;

        dwc3_ep_inc_deq(dep);

        if (req->trb == trb)
                dep->queued_requests--;

        trace_dwc3_complete_trb(dep, trb);

        /*
         * If we're in the middle of series of chained TRBs and we
         * receive a short transfer along the way, DWC3 will skip
         * through all TRBs including the last TRB in the chain (the
         * where CHN bit is zero. DWC3 will also avoid clearing HWO
         * bit and SW has to do it manually.
         *
         * We're going to do that here to avoid problems of HW trying
         * to use bogus TRBs for transfers.
         */
        if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
                trb->ctrl &= ~DWC3_TRB_CTRL_HWO;

        /*
         * If we're dealing with unaligned size OUT transfer, we will be left
         * with one TRB pending in the ring. We need to manually clear HWO bit
         * from that TRB.
         */
        if ((req->zero || req->unaligned) && (trb->ctrl & DWC3_TRB_CTRL_HWO)) {
                trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                return 1;
        }

        count = trb->size & DWC3_TRB_SIZE_MASK;
        req->remaining += count;

        if ((trb->ctrl & DWC3_TRB_CTRL_HWO) && status != -ESHUTDOWN)
                return 1;

        if (dep->direction) {
                if (count) {
                        trb_status = DWC3_TRB_SIZE_TRBSTS(trb->size);
                        if (trb_status == DWC3_TRBSTS_MISSED_ISOC) {
                                /*
                                 * If missed isoc occurred and there is
                                 * no request queued then issue END
                                 * TRANSFER, so that core generates
                                 * next xfernotready and we will issue
                                 * a fresh START TRANSFER.
                                 * If there are still queued request
                                 * then wait, do not issue either END
                                 * or UPDATE TRANSFER, just attach next
                                 * request in pending_list during
                                 * giveback.If any future queued request
                                 * is successfully transferred then we
                                 * will issue UPDATE TRANSFER for all
                                 * request in the pending_list.
                                 */
                                dep->flags |= DWC3_EP_MISSED_ISOC;
                        } else {
                                dev_err(dwc->dev, "incomplete IN transfer %s\n",
                                                dep->name);
                                status = -ECONNRESET;
                        }
                } else {
                        dep->flags &= ~DWC3_EP_MISSED_ISOC;
                }
        } else {
                if (count && (event->status & DEPEVT_STATUS_SHORT))
                        s_pkt = 1;
        }

        if (s_pkt && !chain)
                return 1;

        if ((event->status & DEPEVT_STATUS_IOC) &&
                        (trb->ctrl & DWC3_TRB_CTRL_IOC))
                return 1;

        return 0;
}

static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event, int status)
{
        struct dwc3_request     *req, *n;
        struct dwc3_trb         *trb;
        bool                    ioc = false;
        int                     ret = 0;

        list_for_each_entry_safe(req, n, &dep->started_list, list) {
                unsigned length;
                int chain;

                length = req->request.length;
                chain = req->num_pending_sgs > 0;
                if (chain) {
                        struct scatterlist *sg = req->sg;
                        struct scatterlist *s;
                        unsigned int pending = req->num_pending_sgs;
                        unsigned int i;

                        for_each_sg(sg, s, pending, i) {
                                trb = &dep->trb_pool[dep->trb_dequeue];

                                if (trb->ctrl & DWC3_TRB_CTRL_HWO)
                                        break;

                                req->sg = sg_next(s);
                                req->num_pending_sgs--;

                                ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
                                                event, status, chain);
                                if (ret)
                                        break;
                        }
                } else {
                        trb = &dep->trb_pool[dep->trb_dequeue];
                        ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
                                        event, status, chain);
                }

                if (req->unaligned || req->zero) {
                        trb = &dep->trb_pool[dep->trb_dequeue];
                        ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
                                        event, status, false);
                        req->unaligned = false;
                        req->zero = false;
                }

                req->request.actual = length - req->remaining;

                if ((req->request.actual < length) && req->num_pending_sgs)
                        return __dwc3_gadget_kick_transfer(dep);

                dwc3_gadget_giveback(dep, req, status);

                if (ret) {
                        if ((event->status & DEPEVT_STATUS_IOC) &&
                            (trb->ctrl & DWC3_TRB_CTRL_IOC))
                                ioc = true;
                        break;
                }
        }

        /*
         * Our endpoint might get disabled by another thread during
         * dwc3_gadget_giveback(). If that happens, we're just gonna return 1
         * early on so DWC3_EP_BUSY flag gets cleared
         */
        if (!dep->endpoint.desc)
                return 1;

        if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
                        list_empty(&dep->started_list)) {
                if (list_empty(&dep->pending_list)) {
                        /*
                         * If there is no entry in request list then do
                         * not issue END TRANSFER now. Just set PENDING
                         * flag, so that END TRANSFER is issued when an
                         * entry is added into request list.
                         */
                        dep->flags = DWC3_EP_PENDING_REQUEST;
                } else {
                        dwc3_stop_active_transfer(dwc, dep->number, true);
                        dep->flags = DWC3_EP_ENABLED;
                }
                return 1;
        }

        if (usb_endpoint_xfer_isoc(dep->endpoint.desc) && ioc)
                return 0;

        return 1;
}

static void dwc3_endpoint_transfer_complete(struct dwc3 *dwc,
                struct dwc3_ep *dep, const struct dwc3_event_depevt *event)
{
        unsigned                status = 0;
        int                     clean_busy;
        u32                     is_xfer_complete;

        is_xfer_complete = (event->endpoint_event == DWC3_DEPEVT_XFERCOMPLETE);

        if (event->status & DEPEVT_STATUS_BUSERR)
                status = -ECONNRESET;

        clean_busy = dwc3_cleanup_done_reqs(dwc, dep, event, status);
        if (clean_busy && (!dep->endpoint.desc || is_xfer_complete ||
                                usb_endpoint_xfer_isoc(dep->endpoint.desc)))
                dep->flags &= ~DWC3_EP_BUSY;

        /*
         * WORKAROUND: This is the 2nd half of U1/U2 -> U0 workaround.
         * See dwc3_gadget_linksts_change_interrupt() for 1st half.
         */
        if (dwc->revision < DWC3_REVISION_183A) {
                u32             reg;
                int             i;

                for (i = 0; i < DWC3_ENDPOINTS_NUM; i++) {
                        dep = dwc->eps[i];

                        if (!(dep->flags & DWC3_EP_ENABLED))
                                continue;

                        if (!list_empty(&dep->started_list))
                                return;
                }

                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg |= dwc->u1u2;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);

                dwc->u1u2 = 0;
        }

        /*
         * Our endpoint might get disabled by another thread during
         * dwc3_gadget_giveback(). If that happens, we're just gonna return 1
         * early on so DWC3_EP_BUSY flag gets cleared
         */
        if (!dep->endpoint.desc)
                return;

        if (!usb_endpoint_xfer_isoc(dep->endpoint.desc))
                __dwc3_gadget_kick_transfer(dep);
}

static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_ep          *dep;
        u8                      epnum = event->endpoint_number;
        u8                      cmd;

        dep = dwc->eps[epnum];

        if (!(dep->flags & DWC3_EP_ENABLED)) {
                if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
                        return;

                /* Handle only EPCMDCMPLT when EP disabled */
                if (event->endpoint_event != DWC3_DEPEVT_EPCMDCMPLT)
                        return;
        }

        if (epnum == 0 || epnum == 1) {
                dwc3_ep0_interrupt(dwc, event);
                return;
        }

        switch (event->endpoint_event) {
        case DWC3_DEPEVT_XFERCOMPLETE:
                dep->resource_index = 0;

                if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
                        dev_err(dwc->dev, "XferComplete for Isochronous endpoint\n");
                        return;
                }

                dwc3_endpoint_transfer_complete(dwc, dep, event);
                break;
        case DWC3_DEPEVT_XFERINPROGRESS:
                dwc3_endpoint_transfer_complete(dwc, dep, event);
                break;
        case DWC3_DEPEVT_XFERNOTREADY:
                if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
                        dwc3_gadget_start_isoc(dwc, dep, event);
                else
                        __dwc3_gadget_kick_transfer(dep);

                break;
        case DWC3_DEPEVT_STREAMEVT:
                if (!usb_endpoint_xfer_bulk(dep->endpoint.desc)) {
                        dev_err(dwc->dev, "Stream event for non-Bulk %s\n",
                                        dep->name);
                        return;
                }
                break;
        case DWC3_DEPEVT_EPCMDCMPLT:
                cmd = DEPEVT_PARAMETER_CMD(event->parameters);

                if (cmd == DWC3_DEPCMD_ENDTRANSFER) {
                        dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
                        wake_up(&dep->wait_end_transfer);
                }
                break;
        case DWC3_DEPEVT_RXTXFIFOEVT:
                break;
        }
}

static void dwc3_disconnect_gadget(struct dwc3 *dwc)
{
        if (dwc->gadget_driver && dwc->gadget_driver->disconnect) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->disconnect(&dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_suspend_gadget(struct dwc3 *dwc)
{
        if (dwc->gadget_driver && dwc->gadget_driver->suspend) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->suspend(&dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_resume_gadget(struct dwc3 *dwc)
{
        if (dwc->gadget_driver && dwc->gadget_driver->resume) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->resume(&dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_reset_gadget(struct dwc3 *dwc)
{
        if (!dwc->gadget_driver)
                return;

        if (dwc->gadget.speed != USB_SPEED_UNKNOWN) {
                spin_unlock(&dwc->lock);
                usb_gadget_udc_reset(&dwc->gadget, dwc->gadget_driver);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_stop_active_transfer(struct dwc3 *dwc, u32 epnum, bool force)
{
        struct dwc3_ep *dep;
        struct dwc3_gadget_ep_cmd_params params;
        u32 cmd;
        int ret;

        dep = dwc->eps[epnum];

        if ((dep->flags & DWC3_EP_END_TRANSFER_PENDING) ||
            !dep->resource_index)
                return;

        /*
         * NOTICE: We are violating what the Databook says about the
         * EndTransfer command. Ideally we would _always_ wait for the
         * EndTransfer Command Completion IRQ, but that's causing too
         * much trouble synchronizing between us and gadget driver.
         *
         * We have discussed this with the IP Provider and it was
         * suggested to giveback all requests here, but give HW some
         * extra time to synchronize with the interconnect. We're using
         * an arbitrary 100us delay for that.
         *
         * Note also that a similar handling was tested by Synopsys
         * (thanks a lot Paul) and nothing bad has come out of it.
         * In short, what we're doing is:
         *
         * - Issue EndTransfer WITH CMDIOC bit set
         * - Wait 100us
         *
         * As of IP version 3.10a of the DWC_usb3 IP, the controller
         * supports a mode to work around the above limitation. The
         * software can poll the CMDACT bit in the DEPCMD register
         * after issuing a EndTransfer command. This mode is enabled
         * by writing GUCTL2[14]. This polling is already done in the
         * dwc3_send_gadget_ep_cmd() function so if the mode is
         * enabled, the EndTransfer command will have completed upon
         * returning from this function and we don't need to delay for
         * 100us.
         *
         * This mode is NOT available on the DWC_usb31 IP.
         */

        cmd = DWC3_DEPCMD_ENDTRANSFER;
        cmd |= force ? DWC3_DEPCMD_HIPRI_FORCERM : 0;
        cmd |= DWC3_DEPCMD_CMDIOC;
        cmd |= DWC3_DEPCMD_PARAM(dep->resource_index);
        memset(&params, 0, sizeof(params));
        ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
        WARN_ON_ONCE(ret);
        dep->resource_index = 0;
        dep->flags &= ~DWC3_EP_BUSY;

        if (dwc3_is_usb31(dwc) || dwc->revision < DWC3_REVISION_310A) {
                dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
                udelay(100);
        }
}

static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)
{
        u32 epnum;

        for (epnum = 1; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
                struct dwc3_ep *dep;
                int ret;

                dep = dwc->eps[epnum];
                if (!dep)
                        continue;

                if (!(dep->flags & DWC3_EP_STALL))
                        continue;

                dep->flags &= ~DWC3_EP_STALL;

                ret = dwc3_send_clear_stall_ep_cmd(dep);
                WARN_ON_ONCE(ret);
        }
}

static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
{
        int                     reg;

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_INITU1ENA;
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        reg &= ~DWC3_DCTL_INITU2ENA;
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        dwc3_disconnect_gadget(dwc);

        dwc->gadget.speed = USB_SPEED_UNKNOWN;
        dwc->setup_packet_pending = false;
        usb_gadget_set_state(&dwc->gadget, USB_STATE_NOTATTACHED);

        dwc->connected = false;
}

static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
{
        u32                     reg;

        dwc->connected = true;

        /*
         * WORKAROUND: DWC3 revisions <1.88a have an issue which
         * would cause a missing Disconnect Event if there's a
         * pending Setup Packet in the FIFO.
         *
         * There's no suggested workaround on the official Bug
         * report, which states that "unless the driver/application
         * is doing any special handling of a disconnect event,
         * there is no functional issue".
         *
         * Unfortunately, it turns out that we _do_ some special
         * handling of a disconnect event, namely complete all
         * pending transfers, notify gadget driver of the
         * disconnection, and so on.
         *
         * Our suggested workaround is to follow the Disconnect
         * Event steps here, instead, based on a setup_packet_pending
         * flag. Such flag gets set whenever we have a SETUP_PENDING
         * status for EP0 TRBs and gets cleared on XferComplete for the
         * same endpoint.
         *
         * Refers to:
         *
         * STAR#9000466709: RTL: Device : Disconnect event not
         * generated if setup packet pending in FIFO
         */
        if (dwc->revision < DWC3_REVISION_188A) {
                if (dwc->setup_packet_pending)
                        dwc3_gadget_disconnect_interrupt(dwc);
        }

        dwc3_reset_gadget(dwc);

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_TSTCTRL_MASK;
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        dwc->test_mode = false;
        dwc3_clear_stall_all_ep(dwc);

        /* Reset device address to zero */
        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~(DWC3_DCFG_DEVADDR_MASK);
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);
}

static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
{
        struct dwc3_ep          *dep;
        int                     ret;
        u32                     reg;
        u8                      speed;

        reg = dwc3_readl(dwc->regs, DWC3_DSTS);
        speed = reg & DWC3_DSTS_CONNECTSPD;
        dwc->speed = speed;

        /*
         * RAMClkSel is reset to 0 after USB reset, so it must be reprogrammed
         * each time on Connect Done.
         *
         * Currently we always use the reset value. If any platform
         * wants to set this to a different value, we need to add a
         * setting and update GCTL.RAMCLKSEL here.
         */

        switch (speed) {
        case DWC3_DSTS_SUPERSPEED_PLUS:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
                dwc->gadget.ep0->maxpacket = 512;
                dwc->gadget.speed = USB_SPEED_SUPER_PLUS;
                break;
        case DWC3_DSTS_SUPERSPEED:
                /*
                 * WORKAROUND: DWC3 revisions <1.90a have an issue which
                 * would cause a missing USB3 Reset event.
                 *
                 * In such situations, we should force a USB3 Reset
                 * event by calling our dwc3_gadget_reset_interrupt()
                 * routine.
                 *
                 * Refers to:
                 *
                 * STAR#9000483510: RTL: SS : USB3 reset event may
                 * not be generated always when the link enters poll
                 */
                if (dwc->revision < DWC3_REVISION_190A)
                        dwc3_gadget_reset_interrupt(dwc);

                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
                dwc->gadget.ep0->maxpacket = 512;
                dwc->gadget.speed = USB_SPEED_SUPER;
                break;
        case DWC3_DSTS_HIGHSPEED:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(64);
                dwc->gadget.ep0->maxpacket = 64;
                dwc->gadget.speed = USB_SPEED_HIGH;
                break;
        case DWC3_DSTS_FULLSPEED:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(64);
                dwc->gadget.ep0->maxpacket = 64;
                dwc->gadget.speed = USB_SPEED_FULL;
                break;
        case DWC3_DSTS_LOWSPEED:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(8);
                dwc->gadget.ep0->maxpacket = 8;
                dwc->gadget.speed = USB_SPEED_LOW;
                break;
        }

        dwc->eps[1]->endpoint.maxpacket = dwc->gadget.ep0->maxpacket;

        /* Enable USB2 LPM Capability */

        if ((dwc->revision > DWC3_REVISION_194A) &&
            (speed != DWC3_DSTS_SUPERSPEED) &&
            (speed != DWC3_DSTS_SUPERSPEED_PLUS)) {
                reg = dwc3_readl(dwc->regs, DWC3_DCFG);
                reg |= DWC3_DCFG_LPM_CAP;
                dwc3_writel(dwc->regs, DWC3_DCFG, reg);

                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~(DWC3_DCTL_HIRD_THRES_MASK | DWC3_DCTL_L1_HIBER_EN);

                reg |= DWC3_DCTL_HIRD_THRES(dwc->hird_threshold);

                /*
                 * When dwc3 revisions >= 2.40a, LPM Erratum is enabled and
                 * DCFG.LPMCap is set, core responses with an ACK and the
                 * BESL value in the LPM token is less than or equal to LPM
                 * NYET threshold.
                 */
                WARN_ONCE(dwc->revision < DWC3_REVISION_240A
                                && dwc->has_lpm_erratum,
                                "LPM Erratum not available on dwc3 revisions < 2.40a\n");

                if (dwc->has_lpm_erratum && dwc->revision >= DWC3_REVISION_240A)
                        reg |= DWC3_DCTL_LPM_ERRATA(dwc->lpm_nyet_threshold);

                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        } else {
                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~DWC3_DCTL_HIRD_THRES_MASK;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        }

        dep = dwc->eps[0];
        ret = __dwc3_gadget_ep_enable(dep, true, false);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                return;
        }

        dep = dwc->eps[1];
        ret = __dwc3_gadget_ep_enable(dep, true, false);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                return;
        }

        /*
         * Configure PHY via GUSB3PIPECTLn if required.
         *
         * Update GTXFIFOSIZn
         *
         * In both cases reset values should be sufficient.
         */
}

static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
{
        /*
         * TODO take core out of low power mode when that's
         * implemented.
         */

        if (dwc->gadget_driver && dwc->gadget_driver->resume) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->resume(&dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
                unsigned int evtinfo)
{
        enum dwc3_link_state    next = evtinfo & DWC3_LINK_STATE_MASK;
        unsigned int            pwropt;

        /*
         * WORKAROUND: DWC3 < 2.50a have an issue when configured without
         * Hibernation mode enabled which would show up when device detects
         * host-initiated U3 exit.
         *
         * In that case, device will generate a Link State Change Interrupt
         * from U3 to RESUME which is only necessary if Hibernation is
         * configured in.
         *
         * There are no functional changes due to such spurious event and we
         * just need to ignore it.
         *
         * Refers to:
         *
         * STAR#9000570034 RTL: SS Resume event generated in non-Hibernation
         * operational mode
         */
        pwropt = DWC3_GHWPARAMS1_EN_PWROPT(dwc->hwparams.hwparams1);
        if ((dwc->revision < DWC3_REVISION_250A) &&
                        (pwropt != DWC3_GHWPARAMS1_EN_PWROPT_HIB)) {
                if ((dwc->link_state == DWC3_LINK_STATE_U3) &&
                                (next == DWC3_LINK_STATE_RESUME)) {
                        return;
                }
        }

        /*
         * WORKAROUND: DWC3 Revisions <1.83a have an issue which, depending
         * on the link partner, the USB session might do multiple entry/exit
         * of low power states before a transfer takes place.
         *
         * Due to this problem, we might experience lower throughput. The
         * suggested workaround is to disable DCTL[12:9] bits if we're
         * transitioning from U1/U2 to U0 and enable those bits again
         * after a transfer completes and there are no pending transfers
         * on any of the enabled endpoints.
         *
         * This is the first half of that workaround.
         *
         * Refers to:
         *
         * STAR#9000446952: RTL: Device SS : if U1/U2 ->U0 takes >128us
         * core send LGO_Ux entering U0
         */
        if (dwc->revision < DWC3_REVISION_183A) {
                if (next == DWC3_LINK_STATE_U0) {
                        u32     u1u2;
                        u32     reg;

                        switch (dwc->link_state) {
                        case DWC3_LINK_STATE_U1:
                        case DWC3_LINK_STATE_U2:
                                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                                u1u2 = reg & (DWC3_DCTL_INITU2ENA
                                                | DWC3_DCTL_ACCEPTU2ENA
                                                | DWC3_DCTL_INITU1ENA
                                                | DWC3_DCTL_ACCEPTU1ENA);

                                if (!dwc->u1u2)
                                        dwc->u1u2 = reg & u1u2;

                                reg &= ~u1u2;

                                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
                                break;
                        default:
                                /* do nothing */
                                break;
                        }
                }
        }

        switch (next) {
        case DWC3_LINK_STATE_U1:
                if (dwc->speed == USB_SPEED_SUPER)
                        dwc3_suspend_gadget(dwc);
                break;
        case DWC3_LINK_STATE_U2:
        case DWC3_LINK_STATE_U3:
                dwc3_suspend_gadget(dwc);
                break;
        case DWC3_LINK_STATE_RESUME:
                dwc3_resume_gadget(dwc);
                break;
        default:
                /* do nothing */
                break;
        }

        dwc->link_state = next;
}

static void dwc3_gadget_suspend_interrupt(struct dwc3 *dwc,
                                          unsigned int evtinfo)
{
        enum dwc3_link_state next = evtinfo & DWC3_LINK_STATE_MASK;

        if (dwc->link_state != next && next == DWC3_LINK_STATE_U3)
                dwc3_suspend_gadget(dwc);

        dwc->link_state = next;
}

static void dwc3_gadget_hibernation_interrupt(struct dwc3 *dwc,
                unsigned int evtinfo)
{
        unsigned int is_ss = evtinfo & BIT(4);

        /*
         * WORKAROUND: DWC3 revison 2.20a with hibernation support
         * have a known issue which can cause USB CV TD.9.23 to fail
         * randomly.
         *
         * Because of this issue, core could generate bogus hibernation
         * events which SW needs to ignore.
         *
         * Refers to:
         *
         * STAR#9000546576: Device Mode Hibernation: Issue in USB 2.0
         * Device Fallback from SuperSpeed
         */
        if (is_ss ^ (dwc->speed == USB_SPEED_SUPER))
                return;

        /* enter hibernation here */
}

static void dwc3_gadget_interrupt(struct dwc3 *dwc,
                const struct dwc3_event_devt *event)
{
        switch (event->type) {
        case DWC3_DEVICE_EVENT_DISCONNECT:
                dwc3_gadget_disconnect_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_RESET:
                dwc3_gadget_reset_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_CONNECT_DONE:
                dwc3_gadget_conndone_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_WAKEUP:
                dwc3_gadget_wakeup_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_HIBER_REQ:
                if (dev_WARN_ONCE(dwc->dev, !dwc->has_hibernation,
                                        "unexpected hibernation event\n"))
                        break;

                dwc3_gadget_hibernation_interrupt(dwc, event->event_info);
                break;
        case DWC3_DEVICE_EVENT_LINK_STATUS_CHANGE:
                dwc3_gadget_linksts_change_interrupt(dwc, event->event_info);
                break;
        case DWC3_DEVICE_EVENT_EOPF:
                /* It changed to be suspend event for version 2.30a and above */
                if (dwc->revision >= DWC3_REVISION_230A) {
                        /*
                         * Ignore suspend event until the gadget enters into
                         * USB_STATE_CONFIGURED state.
                         */
                        if (dwc->gadget.state >= USB_STATE_CONFIGURED)
                                dwc3_gadget_suspend_interrupt(dwc,
                                                event->event_info);
                }
                break;
        case DWC3_DEVICE_EVENT_SOF:
        case DWC3_DEVICE_EVENT_ERRATIC_ERROR:
        case DWC3_DEVICE_EVENT_CMD_CMPL:
        case DWC3_DEVICE_EVENT_OVERFLOW:
                break;
        default:
                dev_WARN(dwc->dev, "UNKNOWN IRQ %d\n", event->type);
        }
}

static void dwc3_process_event_entry(struct dwc3 *dwc,
                const union dwc3_event *event)
{
        trace_dwc3_event(event->raw, dwc);

        if (!event->type.is_devspec)
                dwc3_endpoint_interrupt(dwc, &event->depevt);
        else if (event->type.type == DWC3_EVENT_TYPE_DEV)
                dwc3_gadget_interrupt(dwc, &event->devt);
        else
                dev_err(dwc->dev, "UNKNOWN IRQ type %d\n", event->raw);
}

static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
{
        struct dwc3 *dwc = evt->dwc;
        irqreturn_t ret = IRQ_NONE;
        int left;
        u32 reg;

        left = evt->count;

        if (!(evt->flags & DWC3_EVENT_PENDING))
                return IRQ_NONE;

        while (left > 0) {
                union dwc3_event event;

                event.raw = *(u32 *) (evt->cache + evt->lpos);

                dwc3_process_event_entry(dwc, &event);

                /*
                 * FIXME we wrap around correctly to the next entry as
                 * almost all entries are 4 bytes in size. There is one
                 * entry which has 12 bytes which is a regular entry
                 * followed by 8 bytes data. ATM I don't know how
                 * things are organized if we get next to the a
                 * boundary so I worry about that once we try to handle
                 * that.
                 */
                evt->lpos = (evt->lpos + 4) % evt->length;
                left -= 4;
        }

        evt->count = 0;
        evt->flags &= ~DWC3_EVENT_PENDING;
        ret = IRQ_HANDLED;

        /* Unmask interrupt */
        reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));
        reg &= ~DWC3_GEVNTSIZ_INTMASK;
        dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);

        if (dwc->imod_interval) {
                dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB);
                dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval);
        }

        return ret;
}

static irqreturn_t dwc3_thread_interrupt(int irq, void *_evt)
{
        struct dwc3_event_buffer *evt = _evt;
        struct dwc3 *dwc = evt->dwc;
        unsigned long flags;
        irqreturn_t ret = IRQ_NONE;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = dwc3_process_event_buf(evt);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
{
        struct dwc3 *dwc = evt->dwc;
        u32 amount;
        u32 count;
        u32 reg;

        if (pm_runtime_suspended(dwc->dev)) {
                pm_runtime_get(dwc->dev);
                disable_irq_nosync(dwc->irq_gadget);
                dwc->pending_events = true;
                return IRQ_HANDLED;
        }

        /*
         * With PCIe legacy interrupt, test shows that top-half irq handler can
         * be called again after HW interrupt deassertion. Check if bottom-half
         * irq event handler completes before caching new event to prevent
         * losing events.
         */
        if (evt->flags & DWC3_EVENT_PENDING)
                return IRQ_HANDLED;

        count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
        count &= DWC3_GEVNTCOUNT_MASK;
        if (!count)
                return IRQ_NONE;

        evt->count = count;
        evt->flags |= DWC3_EVENT_PENDING;

        /* Mask interrupt */
        reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));
        reg |= DWC3_GEVNTSIZ_INTMASK;
        dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);

        amount = min(count, evt->length - evt->lpos);
        memcpy(evt->cache + evt->lpos, evt->buf + evt->lpos, amount);

        if (amount < count)
                memcpy(evt->cache, evt->buf, count - amount);

        dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);

        return IRQ_WAKE_THREAD;
}

static irqreturn_t dwc3_interrupt(int irq, void *_evt)
{
        struct dwc3_event_buffer        *evt = _evt;

        return dwc3_check_event_buf(evt);
}

static int dwc3_gadget_get_irq(struct dwc3 *dwc)
{
        struct platform_device *dwc3_pdev = to_platform_device(dwc->dev);
        int irq;

        irq = platform_get_irq_byname(dwc3_pdev, "peripheral");
        if (irq > 0)
                goto out;

        if (irq == -EPROBE_DEFER)
                goto out;

        irq = platform_get_irq_byname(dwc3_pdev, "dwc_usb3");
        if (irq > 0)
                goto out;

        if (irq == -EPROBE_DEFER)
                goto out;

        irq = platform_get_irq(dwc3_pdev, 0);
        if (irq > 0)
                goto out;

        if (irq != -EPROBE_DEFER)
                dev_err(dwc->dev, "missing peripheral IRQ\n");

        if (!irq)
                irq = -EINVAL;

out:
        return irq;
}

/**
 * dwc3_gadget_init - initializes gadget related registers
 * @dwc: pointer to our controller context structure
 *
 * Returns 0 on success otherwise negative errno.
 */
int dwc3_gadget_init(struct dwc3 *dwc)
{
        int ret;
        int irq;

        irq = dwc3_gadget_get_irq(dwc);
        if (irq < 0) {
                ret = irq;
                goto err0;
        }

        dwc->irq_gadget = irq;

        dwc->ep0_trb = dma_alloc_coherent(dwc->sysdev,
                                          sizeof(*dwc->ep0_trb) * 2,
                                          &dwc->ep0_trb_addr, GFP_KERNEL);
        if (!dwc->ep0_trb) {
                dev_err(dwc->dev, "failed to allocate ep0 trb\n");
                ret = -ENOMEM;
                goto err0;
        }

        dwc->setup_buf = kzalloc(DWC3_EP0_SETUP_SIZE, GFP_KERNEL);
        if (!dwc->setup_buf) {
                ret = -ENOMEM;
                goto err1;
        }

        dwc->bounce = dma_alloc_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE,
                        &dwc->bounce_addr, GFP_KERNEL);
        if (!dwc->bounce) {
                ret = -ENOMEM;
                goto err2;
        }

        init_completion(&dwc->ep0_in_setup);

        dwc->gadget.ops                 = &dwc3_gadget_ops;
        dwc->gadget.speed               = USB_SPEED_UNKNOWN;
        dwc->gadget.sg_supported        = true;
        dwc->gadget.name                = "dwc3-gadget";
        dwc->gadget.is_otg              = dwc->dr_mode == USB_DR_MODE_OTG;

        /*
         * FIXME We might be setting max_speed to <SUPER, however versions
         * <2.20a of dwc3 have an issue with metastability (documented
         * elsewhere in this driver) which tells us we can't set max speed to
         * anything lower than SUPER.
         *
         * Because gadget.max_speed is only used by composite.c and function
         * drivers (i.e. it won't go into dwc3's registers) we are allowing this
         * to happen so we avoid sending SuperSpeed Capability descriptor
         * together with our BOS descriptor as that could confuse host into
         * thinking we can handle super speed.
         *
         * Note that, in fact, we won't even support GetBOS requests when speed
         * is less than super speed because we don't have means, yet, to tell
         * composite.c that we are USB 2.0 + LPM ECN.
         */
        if (dwc->revision < DWC3_REVISION_220A &&
            !dwc->dis_metastability_quirk)
                dev_info(dwc->dev, "changing max_speed on rev %08x\n",
                                dwc->revision);

        dwc->gadget.max_speed           = dwc->maximum_speed;

        /*
         * REVISIT: Here we should clear all pending IRQs to be
         * sure we're starting from a well known location.
         */

        ret = dwc3_gadget_init_endpoints(dwc, dwc->num_eps);
        if (ret)
                goto err3;

        ret = usb_add_gadget_udc(dwc->dev, &dwc->gadget);
        if (ret) {
                dev_err(dwc->dev, "failed to register udc\n");
                goto err4;
        }

        return 0;

err4:
        dwc3_gadget_free_endpoints(dwc);

err3:
        dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
                        dwc->bounce_addr);

err2:
        kfree(dwc->setup_buf);

err1:
        dma_free_coherent(dwc->sysdev, sizeof(*dwc->ep0_trb) * 2,
                        dwc->ep0_trb, dwc->ep0_trb_addr);

err0:
        return ret;
}

/* -------------------------------------------------------------------------- */

void dwc3_gadget_exit(struct dwc3 *dwc)
{
        usb_del_gadget_udc(&dwc->gadget);
        dwc3_gadget_free_endpoints(dwc);
        dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
                          dwc->bounce_addr);
        kfree(dwc->setup_buf);
        dma_free_coherent(dwc->sysdev, sizeof(*dwc->ep0_trb) * 2,
                          dwc->ep0_trb, dwc->ep0_trb_addr);
}

int dwc3_gadget_suspend(struct dwc3 *dwc)
{
        if (!dwc->gadget_driver)
                return 0;

        dwc3_gadget_run_stop(dwc, false, false);
        dwc3_disconnect_gadget(dwc);
        __dwc3_gadget_stop(dwc);

        return 0;
}

int dwc3_gadget_resume(struct dwc3 *dwc)
{
        int                     ret;

        if (!dwc->gadget_driver)
                return 0;

        ret = __dwc3_gadget_start(dwc);
        if (ret < 0)
                goto err0;

        ret = dwc3_gadget_run_stop(dwc, true, false);
        if (ret < 0)
                goto err1;

        return 0;

err1:
        __dwc3_gadget_stop(dwc);

err0:
        return ret;
}

void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
{
        if (dwc->pending_events) {
                dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
                dwc->pending_events = false;
                enable_irq(dwc->irq_gadget);
        }
}