treewide: remove redundant IS_ERR() before error code check

[linux/fpc-iii.git] / drivers / hid / intel-ish-hid / ishtp / client.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * ISHTP client logic
 *
 * Copyright (c) 2003-2016, Intel Corporation.
 */

#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include "hbm.h"
#include "client.h"

int ishtp_cl_get_tx_free_buffer_size(struct ishtp_cl *cl)
{
        unsigned long tx_free_flags;
        int size;

        spin_lock_irqsave(&cl->tx_free_list_spinlock, tx_free_flags);
        size = cl->tx_ring_free_size * cl->device->fw_client->props.max_msg_length;
        spin_unlock_irqrestore(&cl->tx_free_list_spinlock, tx_free_flags);

        return size;
}
EXPORT_SYMBOL(ishtp_cl_get_tx_free_buffer_size);

int ishtp_cl_get_tx_free_rings(struct ishtp_cl *cl)
{
        return cl->tx_ring_free_size;
}
EXPORT_SYMBOL(ishtp_cl_get_tx_free_rings);

/**
 * ishtp_read_list_flush() - Flush read queue
 * @cl: ishtp client instance
 *
 * Used to remove all entries from read queue for a client
 */
static void ishtp_read_list_flush(struct ishtp_cl *cl)
{
        struct ishtp_cl_rb *rb;
        struct ishtp_cl_rb *next;
        unsigned long   flags;

        spin_lock_irqsave(&cl->dev->read_list_spinlock, flags);
        list_for_each_entry_safe(rb, next, &cl->dev->read_list.list, list)
                if (rb->cl && ishtp_cl_cmp_id(cl, rb->cl)) {
                        list_del(&rb->list);
                        ishtp_io_rb_free(rb);
                }
        spin_unlock_irqrestore(&cl->dev->read_list_spinlock, flags);
}

/**
 * ishtp_cl_flush_queues() - Flush all queues for a client
 * @cl: ishtp client instance
 *
 * Used to remove all queues for a client. This is called when a client device
 * needs reset due to error, S3 resume or during module removal
 *
 * Return: 0 on success else -EINVAL if device is NULL
 */
int ishtp_cl_flush_queues(struct ishtp_cl *cl)
{
        if (WARN_ON(!cl || !cl->dev))
                return -EINVAL;

        ishtp_read_list_flush(cl);

        return 0;
}
EXPORT_SYMBOL(ishtp_cl_flush_queues);

/**
 * ishtp_cl_init() - Initialize all fields of a client device
 * @cl: ishtp client instance
 * @dev: ishtp device
 *
 * Initializes a client device fields: Init spinlocks, init queues etc.
 * This function is called during new client creation
 */
static void ishtp_cl_init(struct ishtp_cl *cl, struct ishtp_device *dev)
{
        memset(cl, 0, sizeof(struct ishtp_cl));
        init_waitqueue_head(&cl->wait_ctrl_res);
        spin_lock_init(&cl->free_list_spinlock);
        spin_lock_init(&cl->in_process_spinlock);
        spin_lock_init(&cl->tx_list_spinlock);
        spin_lock_init(&cl->tx_free_list_spinlock);
        spin_lock_init(&cl->fc_spinlock);
        INIT_LIST_HEAD(&cl->link);
        cl->dev = dev;

        INIT_LIST_HEAD(&cl->free_rb_list.list);
        INIT_LIST_HEAD(&cl->tx_list.list);
        INIT_LIST_HEAD(&cl->tx_free_list.list);
        INIT_LIST_HEAD(&cl->in_process_list.list);

        cl->rx_ring_size = CL_DEF_RX_RING_SIZE;
        cl->tx_ring_size = CL_DEF_TX_RING_SIZE;
        cl->tx_ring_free_size = cl->tx_ring_size;

        /* dma */
        cl->last_tx_path = CL_TX_PATH_IPC;
        cl->last_dma_acked = 1;
        cl->last_dma_addr = NULL;
        cl->last_ipc_acked = 1;
}

/**
 * ishtp_cl_allocate() - allocates client structure and sets it up.
 * @dev: ishtp device
 *
 * Allocate memory for new client device and call to initialize each field.
 *
 * Return: The allocated client instance or NULL on failure
 */
struct ishtp_cl *ishtp_cl_allocate(struct ishtp_cl_device *cl_device)
{
        struct ishtp_cl *cl;

        cl = kmalloc(sizeof(struct ishtp_cl), GFP_KERNEL);
        if (!cl)
                return NULL;

        ishtp_cl_init(cl, cl_device->ishtp_dev);
        return cl;
}
EXPORT_SYMBOL(ishtp_cl_allocate);

/**
 * ishtp_cl_free() - Frees a client device
 * @cl: client device instance
 *
 * Frees a client device
 */
void    ishtp_cl_free(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        unsigned long flags;

        if (!cl)
                return;

        dev = cl->dev;
        if (!dev)
                return;

        spin_lock_irqsave(&dev->cl_list_lock, flags);
        ishtp_cl_free_rx_ring(cl);
        ishtp_cl_free_tx_ring(cl);
        kfree(cl);
        spin_unlock_irqrestore(&dev->cl_list_lock, flags);
}
EXPORT_SYMBOL(ishtp_cl_free);

/**
 * ishtp_cl_link() - Reserve a host id and link the client instance
 * @cl: client device instance
 *
 * This allocates a single bit in the hostmap. This function will make sure
 * that not many client sessions are opened at the same time. Once allocated
 * the client device instance is added to the ishtp device in the current
 * client list
 *
 * Return: 0 or error code on failure
 */
int ishtp_cl_link(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        unsigned long flags, flags_cl;
        int id, ret = 0;

        if (WARN_ON(!cl || !cl->dev))
                return -EINVAL;

        dev = cl->dev;

        spin_lock_irqsave(&dev->device_lock, flags);

        if (dev->open_handle_count >= ISHTP_MAX_OPEN_HANDLE_COUNT) {
                ret = -EMFILE;
                goto unlock_dev;
        }

        id = find_first_zero_bit(dev->host_clients_map, ISHTP_CLIENTS_MAX);

        if (id >= ISHTP_CLIENTS_MAX) {
                spin_unlock_irqrestore(&dev->device_lock, flags);
                dev_err(&cl->device->dev, "id exceeded %d", ISHTP_CLIENTS_MAX);
                return -ENOENT;
        }

        dev->open_handle_count++;
        cl->host_client_id = id;
        spin_lock_irqsave(&dev->cl_list_lock, flags_cl);
        if (dev->dev_state != ISHTP_DEV_ENABLED) {
                ret = -ENODEV;
                goto unlock_cl;
        }
        list_add_tail(&cl->link, &dev->cl_list);
        set_bit(id, dev->host_clients_map);
        cl->state = ISHTP_CL_INITIALIZING;

unlock_cl:
        spin_unlock_irqrestore(&dev->cl_list_lock, flags_cl);
unlock_dev:
        spin_unlock_irqrestore(&dev->device_lock, flags);
        return ret;
}
EXPORT_SYMBOL(ishtp_cl_link);

/**
 * ishtp_cl_unlink() - remove fw_cl from the client device list
 * @cl: client device instance
 *
 * Remove a previously linked device to a ishtp device
 */
void ishtp_cl_unlink(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        struct ishtp_cl *pos;
        unsigned long   flags;

        /* don't shout on error exit path */
        if (!cl || !cl->dev)
                return;

        dev = cl->dev;

        spin_lock_irqsave(&dev->device_lock, flags);
        if (dev->open_handle_count > 0) {
                clear_bit(cl->host_client_id, dev->host_clients_map);
                dev->open_handle_count--;
        }
        spin_unlock_irqrestore(&dev->device_lock, flags);

        /*
         * This checks that 'cl' is actually linked into device's structure,
         * before attempting 'list_del'
         */
        spin_lock_irqsave(&dev->cl_list_lock, flags);
        list_for_each_entry(pos, &dev->cl_list, link)
                if (cl->host_client_id == pos->host_client_id) {
                        list_del_init(&pos->link);
                        break;
                }
        spin_unlock_irqrestore(&dev->cl_list_lock, flags);
}
EXPORT_SYMBOL(ishtp_cl_unlink);

/**
 * ishtp_cl_disconnect() - Send disconnect request to firmware
 * @cl: client device instance
 *
 * Send a disconnect request for a client to firmware.
 *
 * Return: 0 if successful disconnect response from the firmware or error
 * code on failure
 */
int ishtp_cl_disconnect(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        int err;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        dev->print_log(dev, "%s() state %d\n", __func__, cl->state);

        if (cl->state != ISHTP_CL_DISCONNECTING) {
                dev->print_log(dev, "%s() Disconnect in progress\n", __func__);
                return 0;
        }

        if (ishtp_hbm_cl_disconnect_req(dev, cl)) {
                dev->print_log(dev, "%s() Failed to disconnect\n", __func__);
                dev_err(&cl->device->dev, "failed to disconnect.\n");
                return -ENODEV;
        }

        err = wait_event_interruptible_timeout(cl->wait_ctrl_res,
                        (dev->dev_state != ISHTP_DEV_ENABLED ||
                        cl->state == ISHTP_CL_DISCONNECTED),
                        ishtp_secs_to_jiffies(ISHTP_CL_CONNECT_TIMEOUT));

        /*
         * If FW reset arrived, this will happen. Don't check cl->,
         * as 'cl' may be freed already
         */
        if (dev->dev_state != ISHTP_DEV_ENABLED) {
                dev->print_log(dev, "%s() dev_state != ISHTP_DEV_ENABLED\n",
                               __func__);
                return -ENODEV;
        }

        if (cl->state == ISHTP_CL_DISCONNECTED) {
                dev->print_log(dev, "%s() successful\n", __func__);
                return 0;
        }

        return -ENODEV;
}
EXPORT_SYMBOL(ishtp_cl_disconnect);

/**
 * ishtp_cl_is_other_connecting() - Check other client is connecting
 * @cl: client device instance
 *
 * Checks if other client with the same fw client id is connecting
 *
 * Return: true if other client is connected else false
 */
static bool ishtp_cl_is_other_connecting(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        struct ishtp_cl *pos;
        unsigned long   flags;

        if (WARN_ON(!cl || !cl->dev))
                return false;

        dev = cl->dev;
        spin_lock_irqsave(&dev->cl_list_lock, flags);
        list_for_each_entry(pos, &dev->cl_list, link) {
                if ((pos->state == ISHTP_CL_CONNECTING) && (pos != cl) &&
                                cl->fw_client_id == pos->fw_client_id) {
                        spin_unlock_irqrestore(&dev->cl_list_lock, flags);
                        return true;
                }
        }
        spin_unlock_irqrestore(&dev->cl_list_lock, flags);

        return false;
}

/**
 * ishtp_cl_connect() - Send connect request to firmware
 * @cl: client device instance
 *
 * Send a connect request for a client to firmware. If successful it will
 * RX and TX ring buffers
 *
 * Return: 0 if successful connect response from the firmware and able
 * to bind and allocate ring buffers or error code on failure
 */
int ishtp_cl_connect(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        int rets;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        dev->print_log(dev, "%s() current_state = %d\n", __func__, cl->state);

        if (ishtp_cl_is_other_connecting(cl)) {
                dev->print_log(dev, "%s() Busy\n", __func__);
                return  -EBUSY;
        }

        if (ishtp_hbm_cl_connect_req(dev, cl)) {
                dev->print_log(dev, "%s() HBM connect req fail\n", __func__);
                return -ENODEV;
        }

        rets = wait_event_interruptible_timeout(cl->wait_ctrl_res,
                                (dev->dev_state == ISHTP_DEV_ENABLED &&
                                (cl->state == ISHTP_CL_CONNECTED ||
                                 cl->state == ISHTP_CL_DISCONNECTED)),
                                ishtp_secs_to_jiffies(
                                        ISHTP_CL_CONNECT_TIMEOUT));
        /*
         * If FW reset arrived, this will happen. Don't check cl->,
         * as 'cl' may be freed already
         */
        if (dev->dev_state != ISHTP_DEV_ENABLED) {
                dev->print_log(dev, "%s() dev_state != ISHTP_DEV_ENABLED\n",
                               __func__);
                return -EFAULT;
        }

        if (cl->state != ISHTP_CL_CONNECTED) {
                dev->print_log(dev, "%s() state != ISHTP_CL_CONNECTED\n",
                               __func__);
                return -EFAULT;
        }

        rets = cl->status;
        if (rets) {
                dev->print_log(dev, "%s() Invalid status\n", __func__);
                return rets;
        }

        rets = ishtp_cl_device_bind(cl);
        if (rets) {
                dev->print_log(dev, "%s() Bind error\n", __func__);
                ishtp_cl_disconnect(cl);
                return rets;
        }

        rets = ishtp_cl_alloc_rx_ring(cl);
        if (rets) {
                dev->print_log(dev, "%s() Alloc RX ring failed\n", __func__);
                /* if failed allocation, disconnect */
                ishtp_cl_disconnect(cl);
                return rets;
        }

        rets = ishtp_cl_alloc_tx_ring(cl);
        if (rets) {
                dev->print_log(dev, "%s() Alloc TX ring failed\n", __func__);
                /* if failed allocation, disconnect */
                ishtp_cl_free_rx_ring(cl);
                ishtp_cl_disconnect(cl);
                return rets;
        }

        /* Upon successful connection and allocation, emit flow-control */
        rets = ishtp_cl_read_start(cl);

        dev->print_log(dev, "%s() successful\n", __func__);

        return rets;
}
EXPORT_SYMBOL(ishtp_cl_connect);

/**
 * ishtp_cl_read_start() - Prepare to read client message
 * @cl: client device instance
 *
 * Get a free buffer from pool of free read buffers and add to read buffer
 * pool to add contents. Send a flow control request to firmware to be able
 * send next message.
 *
 * Return: 0 if successful or error code on failure
 */
int ishtp_cl_read_start(struct ishtp_cl *cl)
{
        struct ishtp_device *dev;
        struct ishtp_cl_rb *rb;
        int rets;
        int i;
        unsigned long   flags;
        unsigned long   dev_flags;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        if (cl->state != ISHTP_CL_CONNECTED)
                return -ENODEV;

        if (dev->dev_state != ISHTP_DEV_ENABLED)
                return -ENODEV;

        i = ishtp_fw_cl_by_id(dev, cl->fw_client_id);
        if (i < 0) {
                dev_err(&cl->device->dev, "no such fw client %d\n",
                        cl->fw_client_id);
                return -ENODEV;
        }

        /* The current rb is the head of the free rb list */
        spin_lock_irqsave(&cl->free_list_spinlock, flags);
        if (list_empty(&cl->free_rb_list.list)) {
                dev_warn(&cl->device->dev,
                         "[ishtp-ish] Rx buffers pool is empty\n");
                rets = -ENOMEM;
                rb = NULL;
                spin_unlock_irqrestore(&cl->free_list_spinlock, flags);
                goto out;
        }
        rb = list_entry(cl->free_rb_list.list.next, struct ishtp_cl_rb, list);
        list_del_init(&rb->list);
        spin_unlock_irqrestore(&cl->free_list_spinlock, flags);

        rb->cl = cl;
        rb->buf_idx = 0;

        INIT_LIST_HEAD(&rb->list);
        rets = 0;

        /*
         * This must be BEFORE sending flow control -
         * response in ISR may come too fast...
         */
        spin_lock_irqsave(&dev->read_list_spinlock, dev_flags);
        list_add_tail(&rb->list, &dev->read_list.list);
        spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags);
        if (ishtp_hbm_cl_flow_control_req(dev, cl)) {
                rets = -ENODEV;
                goto out;
        }
out:
        /* if ishtp_hbm_cl_flow_control_req failed, return rb to free list */
        if (rets && rb) {
                spin_lock_irqsave(&dev->read_list_spinlock, dev_flags);
                list_del(&rb->list);
                spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags);

                spin_lock_irqsave(&cl->free_list_spinlock, flags);
                list_add_tail(&rb->list, &cl->free_rb_list.list);
                spin_unlock_irqrestore(&cl->free_list_spinlock, flags);
        }
        return rets;
}

/**
 * ishtp_cl_send() - Send a message to firmware
 * @cl: client device instance
 * @buf: message buffer
 * @length: length of message
 *
 * If the client is correct state to send message, this function gets a buffer
 * from tx ring buffers, copy the message data and call to send the message
 * using ishtp_cl_send_msg()
 *
 * Return: 0 if successful or error code on failure
 */
int ishtp_cl_send(struct ishtp_cl *cl, uint8_t *buf, size_t length)
{
        struct ishtp_device     *dev;
        int     id;
        struct ishtp_cl_tx_ring *cl_msg;
        int     have_msg_to_send = 0;
        unsigned long   tx_flags, tx_free_flags;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        if (cl->state != ISHTP_CL_CONNECTED) {
                ++cl->err_send_msg;
                return -EPIPE;
        }

        if (dev->dev_state != ISHTP_DEV_ENABLED) {
                ++cl->err_send_msg;
                return -ENODEV;
        }

        /* Check if we have fw client device */
        id = ishtp_fw_cl_by_id(dev, cl->fw_client_id);
        if (id < 0) {
                ++cl->err_send_msg;
                return -ENOENT;
        }

        if (length > dev->fw_clients[id].props.max_msg_length) {
                ++cl->err_send_msg;
                return -EMSGSIZE;
        }

        /* No free bufs */
        spin_lock_irqsave(&cl->tx_free_list_spinlock, tx_free_flags);
        if (list_empty(&cl->tx_free_list.list)) {
                spin_unlock_irqrestore(&cl->tx_free_list_spinlock,
                        tx_free_flags);
                ++cl->err_send_msg;
                return  -ENOMEM;
        }

        cl_msg = list_first_entry(&cl->tx_free_list.list,
                struct ishtp_cl_tx_ring, list);
        if (!cl_msg->send_buf.data) {
                spin_unlock_irqrestore(&cl->tx_free_list_spinlock,
                        tx_free_flags);
                return  -EIO;
                /* Should not happen, as free list is pre-allocated */
        }
        /*
         * This is safe, as 'length' is already checked for not exceeding
         * max ISHTP message size per client
         */
        list_del_init(&cl_msg->list);
        --cl->tx_ring_free_size;

        spin_unlock_irqrestore(&cl->tx_free_list_spinlock, tx_free_flags);
        memcpy(cl_msg->send_buf.data, buf, length);
        cl_msg->send_buf.size = length;
        spin_lock_irqsave(&cl->tx_list_spinlock, tx_flags);
        have_msg_to_send = !list_empty(&cl->tx_list.list);
        list_add_tail(&cl_msg->list, &cl->tx_list.list);
        spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);

        if (!have_msg_to_send && cl->ishtp_flow_ctrl_creds > 0)
                ishtp_cl_send_msg(dev, cl);

        return  0;
}
EXPORT_SYMBOL(ishtp_cl_send);

/**
 * ishtp_cl_read_complete() - read complete
 * @rb: Pointer to client request block
 *
 * If the message is completely received call ishtp_cl_bus_rx_event()
 * to process message
 */
static void ishtp_cl_read_complete(struct ishtp_cl_rb *rb)
{
        unsigned long   flags;
        int     schedule_work_flag = 0;
        struct ishtp_cl *cl = rb->cl;

        spin_lock_irqsave(&cl->in_process_spinlock, flags);
        /*
         * if in-process list is empty, then need to schedule
         * the processing thread
         */
        schedule_work_flag = list_empty(&cl->in_process_list.list);
        list_add_tail(&rb->list, &cl->in_process_list.list);
        spin_unlock_irqrestore(&cl->in_process_spinlock, flags);

        if (schedule_work_flag)
                ishtp_cl_bus_rx_event(cl->device);
}

/**
 * ipc_tx_callback() - IPC tx callback function
 * @prm: Pointer to client device instance
 *
 * Send message over IPC either first time or on callback on previous message
 * completion
 */
static void ipc_tx_callback(void *prm)
{
        struct ishtp_cl *cl = prm;
        struct ishtp_cl_tx_ring *cl_msg;
        size_t  rem;
        struct ishtp_device     *dev = (cl ? cl->dev : NULL);
        struct ishtp_msg_hdr    ishtp_hdr;
        unsigned long   tx_flags, tx_free_flags;
        unsigned char   *pmsg;

        if (!dev)
                return;

        /*
         * Other conditions if some critical error has
         * occurred before this callback is called
         */
        if (dev->dev_state != ISHTP_DEV_ENABLED)
                return;

        if (cl->state != ISHTP_CL_CONNECTED)
                return;

        spin_lock_irqsave(&cl->tx_list_spinlock, tx_flags);
        if (list_empty(&cl->tx_list.list)) {
                spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);
                return;
        }

        if (cl->ishtp_flow_ctrl_creds != 1 && !cl->sending) {
                spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);
                return;
        }

        if (!cl->sending) {
                --cl->ishtp_flow_ctrl_creds;
                cl->last_ipc_acked = 0;
                cl->last_tx_path = CL_TX_PATH_IPC;
                cl->sending = 1;
        }

        cl_msg = list_entry(cl->tx_list.list.next, struct ishtp_cl_tx_ring,
                            list);
        rem = cl_msg->send_buf.size - cl->tx_offs;

        ishtp_hdr.host_addr = cl->host_client_id;
        ishtp_hdr.fw_addr = cl->fw_client_id;
        ishtp_hdr.reserved = 0;
        pmsg = cl_msg->send_buf.data + cl->tx_offs;

        if (rem <= dev->mtu) {
                ishtp_hdr.length = rem;
                ishtp_hdr.msg_complete = 1;
                cl->sending = 0;
                list_del_init(&cl_msg->list);   /* Must be before write */
                spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);
                /* Submit to IPC queue with no callback */
                ishtp_write_message(dev, &ishtp_hdr, pmsg);
                spin_lock_irqsave(&cl->tx_free_list_spinlock, tx_free_flags);
                list_add_tail(&cl_msg->list, &cl->tx_free_list.list);
                ++cl->tx_ring_free_size;
                spin_unlock_irqrestore(&cl->tx_free_list_spinlock,
                        tx_free_flags);
        } else {
                /* Send IPC fragment */
                spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);
                cl->tx_offs += dev->mtu;
                ishtp_hdr.length = dev->mtu;
                ishtp_hdr.msg_complete = 0;
                ishtp_send_msg(dev, &ishtp_hdr, pmsg, ipc_tx_callback, cl);
        }
}

/**
 * ishtp_cl_send_msg_ipc() -Send message using IPC
 * @dev: ISHTP device instance
 * @cl: Pointer to client device instance
 *
 * Send message over IPC not using DMA
 */
static void ishtp_cl_send_msg_ipc(struct ishtp_device *dev,
                                  struct ishtp_cl *cl)
{
        /* If last DMA message wasn't acked yet, leave this one in Tx queue */
        if (cl->last_tx_path == CL_TX_PATH_DMA && cl->last_dma_acked == 0)
                return;

        cl->tx_offs = 0;
        ipc_tx_callback(cl);
        ++cl->send_msg_cnt_ipc;
}

/**
 * ishtp_cl_send_msg_dma() -Send message using DMA
 * @dev: ISHTP device instance
 * @cl: Pointer to client device instance
 *
 * Send message using DMA
 */
static void ishtp_cl_send_msg_dma(struct ishtp_device *dev,
        struct ishtp_cl *cl)
{
        struct ishtp_msg_hdr    hdr;
        struct dma_xfer_hbm     dma_xfer;
        unsigned char   *msg_addr;
        int off;
        struct ishtp_cl_tx_ring *cl_msg;
        unsigned long tx_flags, tx_free_flags;

        /* If last IPC message wasn't acked yet, leave this one in Tx queue */
        if (cl->last_tx_path == CL_TX_PATH_IPC && cl->last_ipc_acked == 0)
                return;

        spin_lock_irqsave(&cl->tx_list_spinlock, tx_flags);
        if (list_empty(&cl->tx_list.list)) {
                spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);
                return;
        }

        cl_msg = list_entry(cl->tx_list.list.next, struct ishtp_cl_tx_ring,
                list);

        msg_addr = ishtp_cl_get_dma_send_buf(dev, cl_msg->send_buf.size);
        if (!msg_addr) {
                spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);
                if (dev->transfer_path == CL_TX_PATH_DEFAULT)
                        ishtp_cl_send_msg_ipc(dev, cl);
                return;
        }

        list_del_init(&cl_msg->list);   /* Must be before write */
        spin_unlock_irqrestore(&cl->tx_list_spinlock, tx_flags);

        --cl->ishtp_flow_ctrl_creds;
        cl->last_dma_acked = 0;
        cl->last_dma_addr = msg_addr;
        cl->last_tx_path = CL_TX_PATH_DMA;

        /* write msg to dma buf */
        memcpy(msg_addr, cl_msg->send_buf.data, cl_msg->send_buf.size);

        /* send dma_xfer hbm msg */
        off = msg_addr - (unsigned char *)dev->ishtp_host_dma_tx_buf;
        ishtp_hbm_hdr(&hdr, sizeof(struct dma_xfer_hbm));
        dma_xfer.hbm = DMA_XFER;
        dma_xfer.fw_client_id = cl->fw_client_id;
        dma_xfer.host_client_id = cl->host_client_id;
        dma_xfer.reserved = 0;
        dma_xfer.msg_addr = dev->ishtp_host_dma_tx_buf_phys + off;
        dma_xfer.msg_length = cl_msg->send_buf.size;
        dma_xfer.reserved2 = 0;
        ishtp_write_message(dev, &hdr, (unsigned char *)&dma_xfer);
        spin_lock_irqsave(&cl->tx_free_list_spinlock, tx_free_flags);
        list_add_tail(&cl_msg->list, &cl->tx_free_list.list);
        ++cl->tx_ring_free_size;
        spin_unlock_irqrestore(&cl->tx_free_list_spinlock, tx_free_flags);
        ++cl->send_msg_cnt_dma;
}

/**
 * ishtp_cl_send_msg() -Send message using DMA or IPC
 * @dev: ISHTP device instance
 * @cl: Pointer to client device instance
 *
 * Send message using DMA or IPC based on transfer_path
 */
void ishtp_cl_send_msg(struct ishtp_device *dev, struct ishtp_cl *cl)
{
        if (dev->transfer_path == CL_TX_PATH_DMA)
                ishtp_cl_send_msg_dma(dev, cl);
        else
                ishtp_cl_send_msg_ipc(dev, cl);
}

/**
 * recv_ishtp_cl_msg() -Receive client message
 * @dev: ISHTP device instance
 * @ishtp_hdr: Pointer to message header
 *
 * Receive and dispatch ISHTP client messages. This function executes in ISR
 * or work queue context
 */
void recv_ishtp_cl_msg(struct ishtp_device *dev,
                       struct ishtp_msg_hdr *ishtp_hdr)
{
        struct ishtp_cl *cl;
        struct ishtp_cl_rb *rb;
        struct ishtp_cl_rb *new_rb;
        unsigned char *buffer = NULL;
        struct ishtp_cl_rb *complete_rb = NULL;
        unsigned long   flags;
        int     rb_count;

        if (ishtp_hdr->reserved) {
                dev_err(dev->devc, "corrupted message header.\n");
                goto    eoi;
        }

        if (ishtp_hdr->length > IPC_PAYLOAD_SIZE) {
                dev_err(dev->devc,
                        "ISHTP message length in hdr exceeds IPC MTU\n");
                goto    eoi;
        }

        spin_lock_irqsave(&dev->read_list_spinlock, flags);
        rb_count = -1;
        list_for_each_entry(rb, &dev->read_list.list, list) {
                ++rb_count;
                cl = rb->cl;
                if (!cl || !(cl->host_client_id == ishtp_hdr->host_addr &&
                                cl->fw_client_id == ishtp_hdr->fw_addr) ||
                                !(cl->state == ISHTP_CL_CONNECTED))
                        continue;

                 /* If no Rx buffer is allocated, disband the rb */
                if (rb->buffer.size == 0 || rb->buffer.data == NULL) {
                        spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
                        dev_err(&cl->device->dev,
                                "Rx buffer is not allocated.\n");
                        list_del(&rb->list);
                        ishtp_io_rb_free(rb);
                        cl->status = -ENOMEM;
                        goto    eoi;
                }

                /*
                 * If message buffer overflown (exceeds max. client msg
                 * size, drop message and return to free buffer.
                 * Do we need to disconnect such a client? (We don't send
                 * back FC, so communication will be stuck anyway)
                 */
                if (rb->buffer.size < ishtp_hdr->length + rb->buf_idx) {
                        spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
                        dev_err(&cl->device->dev,
                                "message overflow. size %d len %d idx %ld\n",
                                rb->buffer.size, ishtp_hdr->length,
                                rb->buf_idx);
                        list_del(&rb->list);
                        ishtp_cl_io_rb_recycle(rb);
                        cl->status = -EIO;
                        goto    eoi;
                }

                buffer = rb->buffer.data + rb->buf_idx;
                dev->ops->ishtp_read(dev, buffer, ishtp_hdr->length);

                rb->buf_idx += ishtp_hdr->length;
                if (ishtp_hdr->msg_complete) {
                        /* Last fragment in message - it's complete */
                        cl->status = 0;
                        list_del(&rb->list);
                        complete_rb = rb;

                        --cl->out_flow_ctrl_creds;
                        /*
                         * the whole msg arrived, send a new FC, and add a new
                         * rb buffer for the next coming msg
                         */
                        spin_lock(&cl->free_list_spinlock);

                        if (!list_empty(&cl->free_rb_list.list)) {
                                new_rb = list_entry(cl->free_rb_list.list.next,
                                        struct ishtp_cl_rb, list);
                                list_del_init(&new_rb->list);
                                spin_unlock(&cl->free_list_spinlock);
                                new_rb->cl = cl;
                                new_rb->buf_idx = 0;
                                INIT_LIST_HEAD(&new_rb->list);
                                list_add_tail(&new_rb->list,
                                        &dev->read_list.list);

                                ishtp_hbm_cl_flow_control_req(dev, cl);
                        } else {
                                spin_unlock(&cl->free_list_spinlock);
                        }
                }
                /* One more fragment in message (even if this was last) */
                ++cl->recv_msg_num_frags;

                /*
                 * We can safely break here (and in BH too),
                 * a single input message can go only to a single request!
                 */
                break;
        }

        spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
        /* If it's nobody's message, just read and discard it */
        if (!buffer) {
                uint8_t rd_msg_buf[ISHTP_RD_MSG_BUF_SIZE];

                dev_err(dev->devc, "Dropped Rx msg - no request\n");
                dev->ops->ishtp_read(dev, rd_msg_buf, ishtp_hdr->length);
                goto    eoi;
        }

        if (complete_rb) {
                cl = complete_rb->cl;
                cl->ts_rx = ktime_get();
                ++cl->recv_msg_cnt_ipc;
                ishtp_cl_read_complete(complete_rb);
        }
eoi:
        return;
}

/**
 * recv_ishtp_cl_msg_dma() -Receive client message
 * @dev: ISHTP device instance
 * @msg: message pointer
 * @hbm: hbm buffer
 *
 * Receive and dispatch ISHTP client messages using DMA. This function executes
 * in ISR or work queue context
 */
void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
                           struct dma_xfer_hbm *hbm)
{
        struct ishtp_cl *cl;
        struct ishtp_cl_rb *rb;
        struct ishtp_cl_rb *new_rb;
        unsigned char *buffer = NULL;
        struct ishtp_cl_rb *complete_rb = NULL;
        unsigned long   flags;

        spin_lock_irqsave(&dev->read_list_spinlock, flags);

        list_for_each_entry(rb, &dev->read_list.list, list) {
                cl = rb->cl;
                if (!cl || !(cl->host_client_id == hbm->host_client_id &&
                                cl->fw_client_id == hbm->fw_client_id) ||
                                !(cl->state == ISHTP_CL_CONNECTED))
                        continue;

                /*
                 * If no Rx buffer is allocated, disband the rb
                 */
                if (rb->buffer.size == 0 || rb->buffer.data == NULL) {
                        spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
                        dev_err(&cl->device->dev,
                                "response buffer is not allocated.\n");
                        list_del(&rb->list);
                        ishtp_io_rb_free(rb);
                        cl->status = -ENOMEM;
                        goto    eoi;
                }

                /*
                 * If message buffer overflown (exceeds max. client msg
                 * size, drop message and return to free buffer.
                 * Do we need to disconnect such a client? (We don't send
                 * back FC, so communication will be stuck anyway)
                 */
                if (rb->buffer.size < hbm->msg_length) {
                        spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
                        dev_err(&cl->device->dev,
                                "message overflow. size %d len %d idx %ld\n",
                                rb->buffer.size, hbm->msg_length, rb->buf_idx);
                        list_del(&rb->list);
                        ishtp_cl_io_rb_recycle(rb);
                        cl->status = -EIO;
                        goto    eoi;
                }

                buffer = rb->buffer.data;
                memcpy(buffer, msg, hbm->msg_length);
                rb->buf_idx = hbm->msg_length;

                /* Last fragment in message - it's complete */
                cl->status = 0;
                list_del(&rb->list);
                complete_rb = rb;

                --cl->out_flow_ctrl_creds;
                /*
                 * the whole msg arrived, send a new FC, and add a new
                 * rb buffer for the next coming msg
                 */
                spin_lock(&cl->free_list_spinlock);

                if (!list_empty(&cl->free_rb_list.list)) {
                        new_rb = list_entry(cl->free_rb_list.list.next,
                                struct ishtp_cl_rb, list);
                        list_del_init(&new_rb->list);
                        spin_unlock(&cl->free_list_spinlock);
                        new_rb->cl = cl;
                        new_rb->buf_idx = 0;
                        INIT_LIST_HEAD(&new_rb->list);
                        list_add_tail(&new_rb->list,
                                &dev->read_list.list);

                        ishtp_hbm_cl_flow_control_req(dev, cl);
                } else {
                        spin_unlock(&cl->free_list_spinlock);
                }

                /* One more fragment in message (this is always last) */
                ++cl->recv_msg_num_frags;

                /*
                 * We can safely break here (and in BH too),
                 * a single input message can go only to a single request!
                 */
                break;
        }

        spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
        /* If it's nobody's message, just read and discard it */
        if (!buffer) {
                dev_err(dev->devc, "Dropped Rx (DMA) msg - no request\n");
                goto    eoi;
        }

        if (complete_rb) {
                cl = complete_rb->cl;
                cl->ts_rx = ktime_get();
                ++cl->recv_msg_cnt_dma;
                ishtp_cl_read_complete(complete_rb);
        }
eoi:
        return;
}

void *ishtp_get_client_data(struct ishtp_cl *cl)
{
        return cl->client_data;
}
EXPORT_SYMBOL(ishtp_get_client_data);

void ishtp_set_client_data(struct ishtp_cl *cl, void *data)
{
        cl->client_data = data;
}
EXPORT_SYMBOL(ishtp_set_client_data);

struct ishtp_device *ishtp_get_ishtp_device(struct ishtp_cl *cl)
{
        return cl->dev;
}
EXPORT_SYMBOL(ishtp_get_ishtp_device);

void ishtp_set_tx_ring_size(struct ishtp_cl *cl, int size)
{
        cl->tx_ring_size = size;
}
EXPORT_SYMBOL(ishtp_set_tx_ring_size);

void ishtp_set_rx_ring_size(struct ishtp_cl *cl, int size)
{
        cl->rx_ring_size = size;
}
EXPORT_SYMBOL(ishtp_set_rx_ring_size);

void ishtp_set_connection_state(struct ishtp_cl *cl, int state)
{
        cl->state = state;
}
EXPORT_SYMBOL(ishtp_set_connection_state);

void ishtp_cl_set_fw_client_id(struct ishtp_cl *cl, int fw_client_id)
{
        cl->fw_client_id = fw_client_id;
}
EXPORT_SYMBOL(ishtp_cl_set_fw_client_id);