dm thin: fix race between simultaneous io and discards to same block

[linux/fpc-iii.git] / drivers / rapidio / rio.c

/*
 * RapidIO interconnect services
 * (RapidIO Interconnect Specification, http://www.rapidio.org)
 *
 * Copyright 2005 MontaVista Software, Inc.
 * Matt Porter <mporter@kernel.crashing.org>
 *
 * Copyright 2009 Integrated Device Technology, Inc.
 * Alex Bounine <alexandre.bounine@idt.com>
 * - Added Port-Write/Error Management initialization and handling
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/types.h>
#include <linux/kernel.h>

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/rio.h>
#include <linux/rio_drv.h>
#include <linux/rio_ids.h>
#include <linux/rio_regs.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/interrupt.h>

#include "rio.h"

static LIST_HEAD(rio_mports);
static unsigned char next_portid;
static DEFINE_SPINLOCK(rio_mmap_lock);

/**
 * rio_local_get_device_id - Get the base/extended device id for a port
 * @port: RIO master port from which to get the deviceid
 *
 * Reads the base/extended device id from the local device
 * implementing the master port. Returns the 8/16-bit device
 * id.
 */
u16 rio_local_get_device_id(struct rio_mport *port)
{
        u32 result;

        rio_local_read_config_32(port, RIO_DID_CSR, &result);

        return (RIO_GET_DID(port->sys_size, result));
}

/**
 * rio_request_inb_mbox - request inbound mailbox service
 * @mport: RIO master port from which to allocate the mailbox resource
 * @dev_id: Device specific pointer to pass on event
 * @mbox: Mailbox number to claim
 * @entries: Number of entries in inbound mailbox queue
 * @minb: Callback to execute when inbound message is received
 *
 * Requests ownership of an inbound mailbox resource and binds
 * a callback function to the resource. Returns %0 on success.
 */
int rio_request_inb_mbox(struct rio_mport *mport,
                         void *dev_id,
                         int mbox,
                         int entries,
                         void (*minb) (struct rio_mport * mport, void *dev_id, int mbox,
                                       int slot))
{
        int rc = -ENOSYS;
        struct resource *res;

        if (mport->ops->open_inb_mbox == NULL)
                goto out;

        res = kmalloc(sizeof(struct resource), GFP_KERNEL);

        if (res) {
                rio_init_mbox_res(res, mbox, mbox);

                /* Make sure this mailbox isn't in use */
                if ((rc =
                     request_resource(&mport->riores[RIO_INB_MBOX_RESOURCE],
                                      res)) < 0) {
                        kfree(res);
                        goto out;
                }

                mport->inb_msg[mbox].res = res;

                /* Hook the inbound message callback */
                mport->inb_msg[mbox].mcback = minb;

                rc = mport->ops->open_inb_mbox(mport, dev_id, mbox, entries);
        } else
                rc = -ENOMEM;

      out:
        return rc;
}

/**
 * rio_release_inb_mbox - release inbound mailbox message service
 * @mport: RIO master port from which to release the mailbox resource
 * @mbox: Mailbox number to release
 *
 * Releases ownership of an inbound mailbox resource. Returns 0
 * if the request has been satisfied.
 */
int rio_release_inb_mbox(struct rio_mport *mport, int mbox)
{
        if (mport->ops->close_inb_mbox) {
                mport->ops->close_inb_mbox(mport, mbox);

                /* Release the mailbox resource */
                return release_resource(mport->inb_msg[mbox].res);
        } else
                return -ENOSYS;
}

/**
 * rio_request_outb_mbox - request outbound mailbox service
 * @mport: RIO master port from which to allocate the mailbox resource
 * @dev_id: Device specific pointer to pass on event
 * @mbox: Mailbox number to claim
 * @entries: Number of entries in outbound mailbox queue
 * @moutb: Callback to execute when outbound message is sent
 *
 * Requests ownership of an outbound mailbox resource and binds
 * a callback function to the resource. Returns 0 on success.
 */
int rio_request_outb_mbox(struct rio_mport *mport,
                          void *dev_id,
                          int mbox,
                          int entries,
                          void (*moutb) (struct rio_mport * mport, void *dev_id, int mbox, int slot))
{
        int rc = -ENOSYS;
        struct resource *res;

        if (mport->ops->open_outb_mbox == NULL)
                goto out;

        res = kmalloc(sizeof(struct resource), GFP_KERNEL);

        if (res) {
                rio_init_mbox_res(res, mbox, mbox);

                /* Make sure this outbound mailbox isn't in use */
                if ((rc =
                     request_resource(&mport->riores[RIO_OUTB_MBOX_RESOURCE],
                                      res)) < 0) {
                        kfree(res);
                        goto out;
                }

                mport->outb_msg[mbox].res = res;

                /* Hook the inbound message callback */
                mport->outb_msg[mbox].mcback = moutb;

                rc = mport->ops->open_outb_mbox(mport, dev_id, mbox, entries);
        } else
                rc = -ENOMEM;

      out:
        return rc;
}

/**
 * rio_release_outb_mbox - release outbound mailbox message service
 * @mport: RIO master port from which to release the mailbox resource
 * @mbox: Mailbox number to release
 *
 * Releases ownership of an inbound mailbox resource. Returns 0
 * if the request has been satisfied.
 */
int rio_release_outb_mbox(struct rio_mport *mport, int mbox)
{
        if (mport->ops->close_outb_mbox) {
                mport->ops->close_outb_mbox(mport, mbox);

                /* Release the mailbox resource */
                return release_resource(mport->outb_msg[mbox].res);
        } else
                return -ENOSYS;
}

/**
 * rio_setup_inb_dbell - bind inbound doorbell callback
 * @mport: RIO master port to bind the doorbell callback
 * @dev_id: Device specific pointer to pass on event
 * @res: Doorbell message resource
 * @dinb: Callback to execute when doorbell is received
 *
 * Adds a doorbell resource/callback pair into a port's
 * doorbell event list. Returns 0 if the request has been
 * satisfied.
 */
static int
rio_setup_inb_dbell(struct rio_mport *mport, void *dev_id, struct resource *res,
                    void (*dinb) (struct rio_mport * mport, void *dev_id, u16 src, u16 dst,
                                  u16 info))
{
        int rc = 0;
        struct rio_dbell *dbell;

        if (!(dbell = kmalloc(sizeof(struct rio_dbell), GFP_KERNEL))) {
                rc = -ENOMEM;
                goto out;
        }

        dbell->res = res;
        dbell->dinb = dinb;
        dbell->dev_id = dev_id;

        list_add_tail(&dbell->node, &mport->dbells);

      out:
        return rc;
}

/**
 * rio_request_inb_dbell - request inbound doorbell message service
 * @mport: RIO master port from which to allocate the doorbell resource
 * @dev_id: Device specific pointer to pass on event
 * @start: Doorbell info range start
 * @end: Doorbell info range end
 * @dinb: Callback to execute when doorbell is received
 *
 * Requests ownership of an inbound doorbell resource and binds
 * a callback function to the resource. Returns 0 if the request
 * has been satisfied.
 */
int rio_request_inb_dbell(struct rio_mport *mport,
                          void *dev_id,
                          u16 start,
                          u16 end,
                          void (*dinb) (struct rio_mport * mport, void *dev_id, u16 src,
                                        u16 dst, u16 info))
{
        int rc = 0;

        struct resource *res = kmalloc(sizeof(struct resource), GFP_KERNEL);

        if (res) {
                rio_init_dbell_res(res, start, end);

                /* Make sure these doorbells aren't in use */
                if ((rc =
                     request_resource(&mport->riores[RIO_DOORBELL_RESOURCE],
                                      res)) < 0) {
                        kfree(res);
                        goto out;
                }

                /* Hook the doorbell callback */
                rc = rio_setup_inb_dbell(mport, dev_id, res, dinb);
        } else
                rc = -ENOMEM;

      out:
        return rc;
}

/**
 * rio_release_inb_dbell - release inbound doorbell message service
 * @mport: RIO master port from which to release the doorbell resource
 * @start: Doorbell info range start
 * @end: Doorbell info range end
 *
 * Releases ownership of an inbound doorbell resource and removes
 * callback from the doorbell event list. Returns 0 if the request
 * has been satisfied.
 */
int rio_release_inb_dbell(struct rio_mport *mport, u16 start, u16 end)
{
        int rc = 0, found = 0;
        struct rio_dbell *dbell;

        list_for_each_entry(dbell, &mport->dbells, node) {
                if ((dbell->res->start == start) && (dbell->res->end == end)) {
                        found = 1;
                        break;
                }
        }

        /* If we can't find an exact match, fail */
        if (!found) {
                rc = -EINVAL;
                goto out;
        }

        /* Delete from list */
        list_del(&dbell->node);

        /* Release the doorbell resource */
        rc = release_resource(dbell->res);

        /* Free the doorbell event */
        kfree(dbell);

      out:
        return rc;
}

/**
 * rio_request_outb_dbell - request outbound doorbell message range
 * @rdev: RIO device from which to allocate the doorbell resource
 * @start: Doorbell message range start
 * @end: Doorbell message range end
 *
 * Requests ownership of a doorbell message range. Returns a resource
 * if the request has been satisfied or %NULL on failure.
 */
struct resource *rio_request_outb_dbell(struct rio_dev *rdev, u16 start,
                                        u16 end)
{
        struct resource *res = kmalloc(sizeof(struct resource), GFP_KERNEL);

        if (res) {
                rio_init_dbell_res(res, start, end);

                /* Make sure these doorbells aren't in use */
                if (request_resource(&rdev->riores[RIO_DOORBELL_RESOURCE], res)
                    < 0) {
                        kfree(res);
                        res = NULL;
                }
        }

        return res;
}

/**
 * rio_release_outb_dbell - release outbound doorbell message range
 * @rdev: RIO device from which to release the doorbell resource
 * @res: Doorbell resource to be freed
 *
 * Releases ownership of a doorbell message range. Returns 0 if the
 * request has been satisfied.
 */
int rio_release_outb_dbell(struct rio_dev *rdev, struct resource *res)
{
        int rc = release_resource(res);

        kfree(res);

        return rc;
}

/**
 * rio_request_inb_pwrite - request inbound port-write message service
 * @rdev: RIO device to which register inbound port-write callback routine
 * @pwcback: Callback routine to execute when port-write is received
 *
 * Binds a port-write callback function to the RapidIO device.
 * Returns 0 if the request has been satisfied.
 */
int rio_request_inb_pwrite(struct rio_dev *rdev,
        int (*pwcback)(struct rio_dev *rdev, union rio_pw_msg *msg, int step))
{
        int rc = 0;

        spin_lock(&rio_global_list_lock);
        if (rdev->pwcback != NULL)
                rc = -ENOMEM;
        else
                rdev->pwcback = pwcback;

        spin_unlock(&rio_global_list_lock);
        return rc;
}
EXPORT_SYMBOL_GPL(rio_request_inb_pwrite);

/**
 * rio_release_inb_pwrite - release inbound port-write message service
 * @rdev: RIO device which registered for inbound port-write callback
 *
 * Removes callback from the rio_dev structure. Returns 0 if the request
 * has been satisfied.
 */
int rio_release_inb_pwrite(struct rio_dev *rdev)
{
        int rc = -ENOMEM;

        spin_lock(&rio_global_list_lock);
        if (rdev->pwcback) {
                rdev->pwcback = NULL;
                rc = 0;
        }

        spin_unlock(&rio_global_list_lock);
        return rc;
}
EXPORT_SYMBOL_GPL(rio_release_inb_pwrite);

/**
 * rio_map_inb_region -- Map inbound memory region.
 * @mport: Master port.
 * @local: physical address of memory region to be mapped
 * @rbase: RIO base address assigned to this window
 * @size: Size of the memory region
 * @rflags: Flags for mapping.
 *
 * Return: 0 -- Success.
 *
 * This function will create the mapping from RIO space to local memory.
 */
int rio_map_inb_region(struct rio_mport *mport, dma_addr_t local,
                        u64 rbase, u32 size, u32 rflags)
{
        int rc = 0;
        unsigned long flags;

        if (!mport->ops->map_inb)
                return -1;
        spin_lock_irqsave(&rio_mmap_lock, flags);
        rc = mport->ops->map_inb(mport, local, rbase, size, rflags);
        spin_unlock_irqrestore(&rio_mmap_lock, flags);
        return rc;
}
EXPORT_SYMBOL_GPL(rio_map_inb_region);

/**
 * rio_unmap_inb_region -- Unmap the inbound memory region
 * @mport: Master port
 * @lstart: physical address of memory region to be unmapped
 */
void rio_unmap_inb_region(struct rio_mport *mport, dma_addr_t lstart)
{
        unsigned long flags;
        if (!mport->ops->unmap_inb)
                return;
        spin_lock_irqsave(&rio_mmap_lock, flags);
        mport->ops->unmap_inb(mport, lstart);
        spin_unlock_irqrestore(&rio_mmap_lock, flags);
}
EXPORT_SYMBOL_GPL(rio_unmap_inb_region);

/**
 * rio_mport_get_physefb - Helper function that returns register offset
 *                      for Physical Layer Extended Features Block.
 * @port: Master port to issue transaction
 * @local: Indicate a local master port or remote device access
 * @destid: Destination ID of the device
 * @hopcount: Number of switch hops to the device
 */
u32
rio_mport_get_physefb(struct rio_mport *port, int local,
                      u16 destid, u8 hopcount)
{
        u32 ext_ftr_ptr;
        u32 ftr_header;

        ext_ftr_ptr = rio_mport_get_efb(port, local, destid, hopcount, 0);

        while (ext_ftr_ptr)  {
                if (local)
                        rio_local_read_config_32(port, ext_ftr_ptr,
                                                 &ftr_header);
                else
                        rio_mport_read_config_32(port, destid, hopcount,
                                                 ext_ftr_ptr, &ftr_header);

                ftr_header = RIO_GET_BLOCK_ID(ftr_header);
                switch (ftr_header) {

                case RIO_EFB_SER_EP_ID_V13P:
                case RIO_EFB_SER_EP_REC_ID_V13P:
                case RIO_EFB_SER_EP_FREE_ID_V13P:
                case RIO_EFB_SER_EP_ID:
                case RIO_EFB_SER_EP_REC_ID:
                case RIO_EFB_SER_EP_FREE_ID:
                case RIO_EFB_SER_EP_FREC_ID:

                        return ext_ftr_ptr;

                default:
                        break;
                }

                ext_ftr_ptr = rio_mport_get_efb(port, local, destid,
                                                hopcount, ext_ftr_ptr);
        }

        return ext_ftr_ptr;
}

/**
 * rio_get_comptag - Begin or continue searching for a RIO device by component tag
 * @comp_tag: RIO component tag to match
 * @from: Previous RIO device found in search, or %NULL for new search
 *
 * Iterates through the list of known RIO devices. If a RIO device is
 * found with a matching @comp_tag, a pointer to its device
 * structure is returned. Otherwise, %NULL is returned. A new search
 * is initiated by passing %NULL to the @from argument. Otherwise, if
 * @from is not %NULL, searches continue from next device on the global
 * list.
 */
struct rio_dev *rio_get_comptag(u32 comp_tag, struct rio_dev *from)
{
        struct list_head *n;
        struct rio_dev *rdev;

        spin_lock(&rio_global_list_lock);
        n = from ? from->global_list.next : rio_devices.next;

        while (n && (n != &rio_devices)) {
                rdev = rio_dev_g(n);
                if (rdev->comp_tag == comp_tag)
                        goto exit;
                n = n->next;
        }
        rdev = NULL;
exit:
        spin_unlock(&rio_global_list_lock);
        return rdev;
}

/**
 * rio_set_port_lockout - Sets/clears LOCKOUT bit (RIO EM 1.3) for a switch port.
 * @rdev: Pointer to RIO device control structure
 * @pnum: Switch port number to set LOCKOUT bit
 * @lock: Operation : set (=1) or clear (=0)
 */
int rio_set_port_lockout(struct rio_dev *rdev, u32 pnum, int lock)
{
        u32 regval;

        rio_read_config_32(rdev,
                                 rdev->phys_efptr + RIO_PORT_N_CTL_CSR(pnum),
                                 &regval);
        if (lock)
                regval |= RIO_PORT_N_CTL_LOCKOUT;
        else
                regval &= ~RIO_PORT_N_CTL_LOCKOUT;

        rio_write_config_32(rdev,
                                  rdev->phys_efptr + RIO_PORT_N_CTL_CSR(pnum),
                                  regval);
        return 0;
}

/**
 * rio_chk_dev_route - Validate route to the specified device.
 * @rdev:  RIO device failed to respond
 * @nrdev: Last active device on the route to rdev
 * @npnum: nrdev's port number on the route to rdev
 *
 * Follows a route to the specified RIO device to determine the last available
 * device (and corresponding RIO port) on the route.
 */
static int
rio_chk_dev_route(struct rio_dev *rdev, struct rio_dev **nrdev, int *npnum)
{
        u32 result;
        int p_port, rc = -EIO;
        struct rio_dev *prev = NULL;

        /* Find switch with failed RIO link */
        while (rdev->prev && (rdev->prev->pef & RIO_PEF_SWITCH)) {
                if (!rio_read_config_32(rdev->prev, RIO_DEV_ID_CAR, &result)) {
                        prev = rdev->prev;
                        break;
                }
                rdev = rdev->prev;
        }

        if (prev == NULL)
                goto err_out;

        p_port = prev->rswitch->route_table[rdev->destid];

        if (p_port != RIO_INVALID_ROUTE) {
                pr_debug("RIO: link failed on [%s]-P%d\n",
                         rio_name(prev), p_port);
                *nrdev = prev;
                *npnum = p_port;
                rc = 0;
        } else
                pr_debug("RIO: failed to trace route to %s\n", rio_name(rdev));
err_out:
        return rc;
}

/**
 * rio_mport_chk_dev_access - Validate access to the specified device.
 * @mport: Master port to send transactions
 * @destid: Device destination ID in network
 * @hopcount: Number of hops into the network
 */
int
rio_mport_chk_dev_access(struct rio_mport *mport, u16 destid, u8 hopcount)
{
        int i = 0;
        u32 tmp;

        while (rio_mport_read_config_32(mport, destid, hopcount,
                                        RIO_DEV_ID_CAR, &tmp)) {
                i++;
                if (i == RIO_MAX_CHK_RETRY)
                        return -EIO;
                mdelay(1);
        }

        return 0;
}

/**
 * rio_chk_dev_access - Validate access to the specified device.
 * @rdev: Pointer to RIO device control structure
 */
static int rio_chk_dev_access(struct rio_dev *rdev)
{
        return rio_mport_chk_dev_access(rdev->net->hport,
                                        rdev->destid, rdev->hopcount);
}

/**
 * rio_get_input_status - Sends a Link-Request/Input-Status control symbol and
 *                        returns link-response (if requested).
 * @rdev: RIO devive to issue Input-status command
 * @pnum: Device port number to issue the command
 * @lnkresp: Response from a link partner
 */
static int
rio_get_input_status(struct rio_dev *rdev, int pnum, u32 *lnkresp)
{
        u32 regval;
        int checkcount;

        if (lnkresp) {
                /* Read from link maintenance response register
                 * to clear valid bit */
                rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_MNT_RSP_CSR(pnum),
                        &regval);
                udelay(50);
        }

        /* Issue Input-status command */
        rio_write_config_32(rdev,
                rdev->phys_efptr + RIO_PORT_N_MNT_REQ_CSR(pnum),
                RIO_MNT_REQ_CMD_IS);

        /* Exit if the response is not expected */
        if (lnkresp == NULL)
                return 0;

        checkcount = 3;
        while (checkcount--) {
                udelay(50);
                rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_MNT_RSP_CSR(pnum),
                        &regval);
                if (regval & RIO_PORT_N_MNT_RSP_RVAL) {
                        *lnkresp = regval;
                        return 0;
                }
        }

        return -EIO;
}

/**
 * rio_clr_err_stopped - Clears port Error-stopped states.
 * @rdev: Pointer to RIO device control structure
 * @pnum: Switch port number to clear errors
 * @err_status: port error status (if 0 reads register from device)
 */
static int rio_clr_err_stopped(struct rio_dev *rdev, u32 pnum, u32 err_status)
{
        struct rio_dev *nextdev = rdev->rswitch->nextdev[pnum];
        u32 regval;
        u32 far_ackid, far_linkstat, near_ackid;

        if (err_status == 0)
                rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_ERR_STS_CSR(pnum),
                        &err_status);

        if (err_status & RIO_PORT_N_ERR_STS_PW_OUT_ES) {
                pr_debug("RIO_EM: servicing Output Error-Stopped state\n");
                /*
                 * Send a Link-Request/Input-Status control symbol
                 */
                if (rio_get_input_status(rdev, pnum, &regval)) {
                        pr_debug("RIO_EM: Input-status response timeout\n");
                        goto rd_err;
                }

                pr_debug("RIO_EM: SP%d Input-status response=0x%08x\n",
                         pnum, regval);
                far_ackid = (regval & RIO_PORT_N_MNT_RSP_ASTAT) >> 5;
                far_linkstat = regval & RIO_PORT_N_MNT_RSP_LSTAT;
                rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_ACK_STS_CSR(pnum),
                        &regval);
                pr_debug("RIO_EM: SP%d_ACK_STS_CSR=0x%08x\n", pnum, regval);
                near_ackid = (regval & RIO_PORT_N_ACK_INBOUND) >> 24;
                pr_debug("RIO_EM: SP%d far_ackID=0x%02x far_linkstat=0x%02x" \
                         " near_ackID=0x%02x\n",
                        pnum, far_ackid, far_linkstat, near_ackid);

                /*
                 * If required, synchronize ackIDs of near and
                 * far sides.
                 */
                if ((far_ackid != ((regval & RIO_PORT_N_ACK_OUTSTAND) >> 8)) ||
                    (far_ackid != (regval & RIO_PORT_N_ACK_OUTBOUND))) {
                        /* Align near outstanding/outbound ackIDs with
                         * far inbound.
                         */
                        rio_write_config_32(rdev,
                                rdev->phys_efptr + RIO_PORT_N_ACK_STS_CSR(pnum),
                                (near_ackid << 24) |
                                        (far_ackid << 8) | far_ackid);
                        /* Align far outstanding/outbound ackIDs with
                         * near inbound.
                         */
                        far_ackid++;
                        if (nextdev)
                                rio_write_config_32(nextdev,
                                        nextdev->phys_efptr +
                                        RIO_PORT_N_ACK_STS_CSR(RIO_GET_PORT_NUM(nextdev->swpinfo)),
                                        (far_ackid << 24) |
                                        (near_ackid << 8) | near_ackid);
                        else
                                pr_debug("RIO_EM: Invalid nextdev pointer (NULL)\n");
                }
rd_err:
                rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_ERR_STS_CSR(pnum),
                        &err_status);
                pr_debug("RIO_EM: SP%d_ERR_STS_CSR=0x%08x\n", pnum, err_status);
        }

        if ((err_status & RIO_PORT_N_ERR_STS_PW_INP_ES) && nextdev) {
                pr_debug("RIO_EM: servicing Input Error-Stopped state\n");
                rio_get_input_status(nextdev,
                                     RIO_GET_PORT_NUM(nextdev->swpinfo), NULL);
                udelay(50);

                rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_ERR_STS_CSR(pnum),
                        &err_status);
                pr_debug("RIO_EM: SP%d_ERR_STS_CSR=0x%08x\n", pnum, err_status);
        }

        return (err_status & (RIO_PORT_N_ERR_STS_PW_OUT_ES |
                              RIO_PORT_N_ERR_STS_PW_INP_ES)) ? 1 : 0;
}

/**
 * rio_inb_pwrite_handler - process inbound port-write message
 * @pw_msg: pointer to inbound port-write message
 *
 * Processes an inbound port-write message. Returns 0 if the request
 * has been satisfied.
 */
int rio_inb_pwrite_handler(union rio_pw_msg *pw_msg)
{
        struct rio_dev *rdev;
        u32 err_status, em_perrdet, em_ltlerrdet;
        int rc, portnum;

        rdev = rio_get_comptag((pw_msg->em.comptag & RIO_CTAG_UDEVID), NULL);
        if (rdev == NULL) {
                /* Device removed or enumeration error */
                pr_debug("RIO: %s No matching device for CTag 0x%08x\n",
                        __func__, pw_msg->em.comptag);
                return -EIO;
        }

        pr_debug("RIO: Port-Write message from %s\n", rio_name(rdev));

#ifdef DEBUG_PW
        {
        u32 i;
        for (i = 0; i < RIO_PW_MSG_SIZE/sizeof(u32);) {
                        pr_debug("0x%02x: %08x %08x %08x %08x\n",
                                 i*4, pw_msg->raw[i], pw_msg->raw[i + 1],
                                 pw_msg->raw[i + 2], pw_msg->raw[i + 3]);
                        i += 4;
        }
        }
#endif

        /* Call an external service function (if such is registered
         * for this device). This may be the service for endpoints that send
         * device-specific port-write messages. End-point messages expected
         * to be handled completely by EP specific device driver.
         * For switches rc==0 signals that no standard processing required.
         */
        if (rdev->pwcback != NULL) {
                rc = rdev->pwcback(rdev, pw_msg, 0);
                if (rc == 0)
                        return 0;
        }

        portnum = pw_msg->em.is_port & 0xFF;

        /* Check if device and route to it are functional:
         * Sometimes devices may send PW message(s) just before being
         * powered down (or link being lost).
         */
        if (rio_chk_dev_access(rdev)) {
                pr_debug("RIO: device access failed - get link partner\n");
                /* Scan route to the device and identify failed link.
                 * This will replace device and port reported in PW message.
                 * PW message should not be used after this point.
                 */
                if (rio_chk_dev_route(rdev, &rdev, &portnum)) {
                        pr_err("RIO: Route trace for %s failed\n",
                                rio_name(rdev));
                        return -EIO;
                }
                pw_msg = NULL;
        }

        /* For End-point devices processing stops here */
        if (!(rdev->pef & RIO_PEF_SWITCH))
                return 0;

        if (rdev->phys_efptr == 0) {
                pr_err("RIO_PW: Bad switch initialization for %s\n",
                        rio_name(rdev));
                return 0;
        }

        /*
         * Process the port-write notification from switch
         */
        if (rdev->rswitch->em_handle)
                rdev->rswitch->em_handle(rdev, portnum);

        rio_read_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_ERR_STS_CSR(portnum),
                        &err_status);
        pr_debug("RIO_PW: SP%d_ERR_STS_CSR=0x%08x\n", portnum, err_status);

        if (err_status & RIO_PORT_N_ERR_STS_PORT_OK) {

                if (!(rdev->rswitch->port_ok & (1 << portnum))) {
                        rdev->rswitch->port_ok |= (1 << portnum);
                        rio_set_port_lockout(rdev, portnum, 0);
                        /* Schedule Insertion Service */
                        pr_debug("RIO_PW: Device Insertion on [%s]-P%d\n",
                               rio_name(rdev), portnum);
                }

                /* Clear error-stopped states (if reported).
                 * Depending on the link partner state, two attempts
                 * may be needed for successful recovery.
                 */
                if (err_status & (RIO_PORT_N_ERR_STS_PW_OUT_ES |
                                  RIO_PORT_N_ERR_STS_PW_INP_ES)) {
                        if (rio_clr_err_stopped(rdev, portnum, err_status))
                                rio_clr_err_stopped(rdev, portnum, 0);
                }
        }  else { /* if (err_status & RIO_PORT_N_ERR_STS_PORT_UNINIT) */

                if (rdev->rswitch->port_ok & (1 << portnum)) {
                        rdev->rswitch->port_ok &= ~(1 << portnum);
                        rio_set_port_lockout(rdev, portnum, 1);

                        rio_write_config_32(rdev,
                                rdev->phys_efptr +
                                        RIO_PORT_N_ACK_STS_CSR(portnum),
                                RIO_PORT_N_ACK_CLEAR);

                        /* Schedule Extraction Service */
                        pr_debug("RIO_PW: Device Extraction on [%s]-P%d\n",
                               rio_name(rdev), portnum);
                }
        }

        rio_read_config_32(rdev,
                rdev->em_efptr + RIO_EM_PN_ERR_DETECT(portnum), &em_perrdet);
        if (em_perrdet) {
                pr_debug("RIO_PW: RIO_EM_P%d_ERR_DETECT=0x%08x\n",
                         portnum, em_perrdet);
                /* Clear EM Port N Error Detect CSR */
                rio_write_config_32(rdev,
                        rdev->em_efptr + RIO_EM_PN_ERR_DETECT(portnum), 0);
        }

        rio_read_config_32(rdev,
                rdev->em_efptr + RIO_EM_LTL_ERR_DETECT, &em_ltlerrdet);
        if (em_ltlerrdet) {
                pr_debug("RIO_PW: RIO_EM_LTL_ERR_DETECT=0x%08x\n",
                         em_ltlerrdet);
                /* Clear EM L/T Layer Error Detect CSR */
                rio_write_config_32(rdev,
                        rdev->em_efptr + RIO_EM_LTL_ERR_DETECT, 0);
        }

        /* Clear remaining error bits and Port-Write Pending bit */
        rio_write_config_32(rdev,
                        rdev->phys_efptr + RIO_PORT_N_ERR_STS_CSR(portnum),
                        err_status);

        return 0;
}
EXPORT_SYMBOL_GPL(rio_inb_pwrite_handler);

/**
 * rio_mport_get_efb - get pointer to next extended features block
 * @port: Master port to issue transaction
 * @local: Indicate a local master port or remote device access
 * @destid: Destination ID of the device
 * @hopcount: Number of switch hops to the device
 * @from: Offset of  current Extended Feature block header (if 0 starts
 * from ExtFeaturePtr)
 */
u32
rio_mport_get_efb(struct rio_mport *port, int local, u16 destid,
                      u8 hopcount, u32 from)
{
        u32 reg_val;

        if (from == 0) {
                if (local)
                        rio_local_read_config_32(port, RIO_ASM_INFO_CAR,
                                                 &reg_val);
                else
                        rio_mport_read_config_32(port, destid, hopcount,
                                                 RIO_ASM_INFO_CAR, &reg_val);
                return reg_val & RIO_EXT_FTR_PTR_MASK;
        } else {
                if (local)
                        rio_local_read_config_32(port, from, &reg_val);
                else
                        rio_mport_read_config_32(port, destid, hopcount,
                                                 from, &reg_val);
                return RIO_GET_BLOCK_ID(reg_val);
        }
}

/**
 * rio_mport_get_feature - query for devices' extended features
 * @port: Master port to issue transaction
 * @local: Indicate a local master port or remote device access
 * @destid: Destination ID of the device
 * @hopcount: Number of switch hops to the device
 * @ftr: Extended feature code
 *
 * Tell if a device supports a given RapidIO capability.
 * Returns the offset of the requested extended feature
 * block within the device's RIO configuration space or
 * 0 in case the device does not support it.  Possible
 * values for @ftr:
 *
 * %RIO_EFB_PAR_EP_ID           LP/LVDS EP Devices
 *
 * %RIO_EFB_PAR_EP_REC_ID       LP/LVDS EP Recovery Devices
 *
 * %RIO_EFB_PAR_EP_FREE_ID      LP/LVDS EP Free Devices
 *
 * %RIO_EFB_SER_EP_ID           LP/Serial EP Devices
 *
 * %RIO_EFB_SER_EP_REC_ID       LP/Serial EP Recovery Devices
 *
 * %RIO_EFB_SER_EP_FREE_ID      LP/Serial EP Free Devices
 */
u32
rio_mport_get_feature(struct rio_mport * port, int local, u16 destid,
                      u8 hopcount, int ftr)
{
        u32 asm_info, ext_ftr_ptr, ftr_header;

        if (local)
                rio_local_read_config_32(port, RIO_ASM_INFO_CAR, &asm_info);
        else
                rio_mport_read_config_32(port, destid, hopcount,
                                         RIO_ASM_INFO_CAR, &asm_info);

        ext_ftr_ptr = asm_info & RIO_EXT_FTR_PTR_MASK;

        while (ext_ftr_ptr) {
                if (local)
                        rio_local_read_config_32(port, ext_ftr_ptr,
                                                 &ftr_header);
                else
                        rio_mport_read_config_32(port, destid, hopcount,
                                                 ext_ftr_ptr, &ftr_header);
                if (RIO_GET_BLOCK_ID(ftr_header) == ftr)
                        return ext_ftr_ptr;
                if (!(ext_ftr_ptr = RIO_GET_BLOCK_PTR(ftr_header)))
                        break;
        }

        return 0;
}

/**
 * rio_get_asm - Begin or continue searching for a RIO device by vid/did/asm_vid/asm_did
 * @vid: RIO vid to match or %RIO_ANY_ID to match all vids
 * @did: RIO did to match or %RIO_ANY_ID to match all dids
 * @asm_vid: RIO asm_vid to match or %RIO_ANY_ID to match all asm_vids
 * @asm_did: RIO asm_did to match or %RIO_ANY_ID to match all asm_dids
 * @from: Previous RIO device found in search, or %NULL for new search
 *
 * Iterates through the list of known RIO devices. If a RIO device is
 * found with a matching @vid, @did, @asm_vid, @asm_did, the reference
 * count to the device is incrememted and a pointer to its device
 * structure is returned. Otherwise, %NULL is returned. A new search
 * is initiated by passing %NULL to the @from argument. Otherwise, if
 * @from is not %NULL, searches continue from next device on the global
 * list. The reference count for @from is always decremented if it is
 * not %NULL.
 */
struct rio_dev *rio_get_asm(u16 vid, u16 did,
                            u16 asm_vid, u16 asm_did, struct rio_dev *from)
{
        struct list_head *n;
        struct rio_dev *rdev;

        WARN_ON(in_interrupt());
        spin_lock(&rio_global_list_lock);
        n = from ? from->global_list.next : rio_devices.next;

        while (n && (n != &rio_devices)) {
                rdev = rio_dev_g(n);
                if ((vid == RIO_ANY_ID || rdev->vid == vid) &&
                    (did == RIO_ANY_ID || rdev->did == did) &&
                    (asm_vid == RIO_ANY_ID || rdev->asm_vid == asm_vid) &&
                    (asm_did == RIO_ANY_ID || rdev->asm_did == asm_did))
                        goto exit;
                n = n->next;
        }
        rdev = NULL;
      exit:
        rio_dev_put(from);
        rdev = rio_dev_get(rdev);
        spin_unlock(&rio_global_list_lock);
        return rdev;
}

/**
 * rio_get_device - Begin or continue searching for a RIO device by vid/did
 * @vid: RIO vid to match or %RIO_ANY_ID to match all vids
 * @did: RIO did to match or %RIO_ANY_ID to match all dids
 * @from: Previous RIO device found in search, or %NULL for new search
 *
 * Iterates through the list of known RIO devices. If a RIO device is
 * found with a matching @vid and @did, the reference count to the
 * device is incrememted and a pointer to its device structure is returned.
 * Otherwise, %NULL is returned. A new search is initiated by passing %NULL
 * to the @from argument. Otherwise, if @from is not %NULL, searches
 * continue from next device on the global list. The reference count for
 * @from is always decremented if it is not %NULL.
 */
struct rio_dev *rio_get_device(u16 vid, u16 did, struct rio_dev *from)
{
        return rio_get_asm(vid, did, RIO_ANY_ID, RIO_ANY_ID, from);
}

/**
 * rio_std_route_add_entry - Add switch route table entry using standard
 *   registers defined in RIO specification rev.1.3
 * @mport: Master port to issue transaction
 * @destid: Destination ID of the device
 * @hopcount: Number of switch hops to the device
 * @table: routing table ID (global or port-specific)
 * @route_destid: destID entry in the RT
 * @route_port: destination port for specified destID
 */
int rio_std_route_add_entry(struct rio_mport *mport, u16 destid, u8 hopcount,
                       u16 table, u16 route_destid, u8 route_port)
{
        if (table == RIO_GLOBAL_TABLE) {
                rio_mport_write_config_32(mport, destid, hopcount,
                                RIO_STD_RTE_CONF_DESTID_SEL_CSR,
                                (u32)route_destid);
                rio_mport_write_config_32(mport, destid, hopcount,
                                RIO_STD_RTE_CONF_PORT_SEL_CSR,
                                (u32)route_port);
        }

        udelay(10);
        return 0;
}

/**
 * rio_std_route_get_entry - Read switch route table entry (port number)
 *   associated with specified destID using standard registers defined in RIO
 *   specification rev.1.3
 * @mport: Master port to issue transaction
 * @destid: Destination ID of the device
 * @hopcount: Number of switch hops to the device
 * @table: routing table ID (global or port-specific)
 * @route_destid: destID entry in the RT
 * @route_port: returned destination port for specified destID
 */
int rio_std_route_get_entry(struct rio_mport *mport, u16 destid, u8 hopcount,
                       u16 table, u16 route_destid, u8 *route_port)
{
        u32 result;

        if (table == RIO_GLOBAL_TABLE) {
                rio_mport_write_config_32(mport, destid, hopcount,
                                RIO_STD_RTE_CONF_DESTID_SEL_CSR, route_destid);
                rio_mport_read_config_32(mport, destid, hopcount,
                                RIO_STD_RTE_CONF_PORT_SEL_CSR, &result);

                *route_port = (u8)result;
        }

        return 0;
}

/**
 * rio_std_route_clr_table - Clear swotch route table using standard registers
 *   defined in RIO specification rev.1.3.
 * @mport: Master port to issue transaction
 * @destid: Destination ID of the device
 * @hopcount: Number of switch hops to the device
 * @table: routing table ID (global or port-specific)
 */
int rio_std_route_clr_table(struct rio_mport *mport, u16 destid, u8 hopcount,
                       u16 table)
{
        u32 max_destid = 0xff;
        u32 i, pef, id_inc = 1, ext_cfg = 0;
        u32 port_sel = RIO_INVALID_ROUTE;

        if (table == RIO_GLOBAL_TABLE) {
                rio_mport_read_config_32(mport, destid, hopcount,
                                         RIO_PEF_CAR, &pef);

                if (mport->sys_size) {
                        rio_mport_read_config_32(mport, destid, hopcount,
                                                 RIO_SWITCH_RT_LIMIT,
                                                 &max_destid);
                        max_destid &= RIO_RT_MAX_DESTID;
                }

                if (pef & RIO_PEF_EXT_RT) {
                        ext_cfg = 0x80000000;
                        id_inc = 4;
                        port_sel = (RIO_INVALID_ROUTE << 24) |
                                   (RIO_INVALID_ROUTE << 16) |
                                   (RIO_INVALID_ROUTE << 8) |
                                   RIO_INVALID_ROUTE;
                }

                for (i = 0; i <= max_destid;) {
                        rio_mport_write_config_32(mport, destid, hopcount,
                                        RIO_STD_RTE_CONF_DESTID_SEL_CSR,
                                        ext_cfg | i);
                        rio_mport_write_config_32(mport, destid, hopcount,
                                        RIO_STD_RTE_CONF_PORT_SEL_CSR,
                                        port_sel);
                        i += id_inc;
                }
        }

        udelay(10);
        return 0;
}

#ifdef CONFIG_RAPIDIO_DMA_ENGINE

static bool rio_chan_filter(struct dma_chan *chan, void *arg)
{
        struct rio_dev *rdev = arg;

        /* Check that DMA device belongs to the right MPORT */
        return (rdev->net->hport ==
                container_of(chan->device, struct rio_mport, dma));
}

/**
 * rio_request_dma - request RapidIO capable DMA channel that supports
 *   specified target RapidIO device.
 * @rdev: RIO device control structure
 *
 * Returns pointer to allocated DMA channel or NULL if failed.
 */
struct dma_chan *rio_request_dma(struct rio_dev *rdev)
{
        dma_cap_mask_t mask;
        struct dma_chan *dchan;

        dma_cap_zero(mask);
        dma_cap_set(DMA_SLAVE, mask);
        dchan = dma_request_channel(mask, rio_chan_filter, rdev);

        return dchan;
}
EXPORT_SYMBOL_GPL(rio_request_dma);

/**
 * rio_release_dma - release specified DMA channel
 * @dchan: DMA channel to release
 */
void rio_release_dma(struct dma_chan *dchan)
{
        dma_release_channel(dchan);
}
EXPORT_SYMBOL_GPL(rio_release_dma);

/**
 * rio_dma_prep_slave_sg - RapidIO specific wrapper
 *   for device_prep_slave_sg callback defined by DMAENGINE.
 * @rdev: RIO device control structure
 * @dchan: DMA channel to configure
 * @data: RIO specific data descriptor
 * @direction: DMA data transfer direction (TO or FROM the device)
 * @flags: dmaengine defined flags
 *
 * Initializes RapidIO capable DMA channel for the specified data transfer.
 * Uses DMA channel private extension to pass information related to remote
 * target RIO device.
 * Returns pointer to DMA transaction descriptor or NULL if failed.
 */
struct dma_async_tx_descriptor *rio_dma_prep_slave_sg(struct rio_dev *rdev,
        struct dma_chan *dchan, struct rio_dma_data *data,
        enum dma_transfer_direction direction, unsigned long flags)
{
        struct dma_async_tx_descriptor *txd = NULL;
        struct rio_dma_ext rio_ext;

        if (dchan->device->device_prep_slave_sg == NULL) {
                pr_err("%s: prep_rio_sg == NULL\n", __func__);
                return NULL;
        }

        rio_ext.destid = rdev->destid;
        rio_ext.rio_addr_u = data->rio_addr_u;
        rio_ext.rio_addr = data->rio_addr;
        rio_ext.wr_type = data->wr_type;

        txd = dmaengine_prep_rio_sg(dchan, data->sg, data->sg_len,
                                        direction, flags, &rio_ext);

        return txd;
}
EXPORT_SYMBOL_GPL(rio_dma_prep_slave_sg);

#endif /* CONFIG_RAPIDIO_DMA_ENGINE */

static void rio_fixup_device(struct rio_dev *dev)
{
}

static int __devinit rio_init(void)
{
        struct rio_dev *dev = NULL;

        while ((dev = rio_get_device(RIO_ANY_ID, RIO_ANY_ID, dev)) != NULL) {
                rio_fixup_device(dev);
        }
        return 0;
}

static struct workqueue_struct *rio_wq;

struct rio_disc_work {
        struct work_struct      work;
        struct rio_mport        *mport;
};

static void __devinit disc_work_handler(struct work_struct *_work)
{
        struct rio_disc_work *work;

        work = container_of(_work, struct rio_disc_work, work);
        pr_debug("RIO: discovery work for mport %d %s\n",
                 work->mport->id, work->mport->name);
        rio_disc_mport(work->mport);
}

int __devinit rio_init_mports(void)
{
        struct rio_mport *port;
        struct rio_disc_work *work;
        int n = 0;

        if (!next_portid)
                return -ENODEV;

        /*
         * First, run enumerations and check if we need to perform discovery
         * on any of the registered mports.
         */
        list_for_each_entry(port, &rio_mports, node) {
                if (port->host_deviceid >= 0)
                        rio_enum_mport(port);
                else
                        n++;
        }

        if (!n)
                goto no_disc;

        /*
         * If we have mports that require discovery schedule a discovery work
         * for each of them. If the code below fails to allocate needed
         * resources, exit without error to keep results of enumeration
         * process (if any).
         * TODO: Implement restart of dicovery process for all or
         * individual discovering mports.
         */
        rio_wq = alloc_workqueue("riodisc", 0, 0);
        if (!rio_wq) {
                pr_err("RIO: unable allocate rio_wq\n");
                goto no_disc;
        }

        work = kcalloc(n, sizeof *work, GFP_KERNEL);
        if (!work) {
                pr_err("RIO: no memory for work struct\n");
                destroy_workqueue(rio_wq);
                goto no_disc;
        }

        n = 0;
        list_for_each_entry(port, &rio_mports, node) {
                if (port->host_deviceid < 0) {
                        work[n].mport = port;
                        INIT_WORK(&work[n].work, disc_work_handler);
                        queue_work(rio_wq, &work[n].work);
                        n++;
                }
        }

        flush_workqueue(rio_wq);
        pr_debug("RIO: destroy discovery workqueue\n");
        destroy_workqueue(rio_wq);
        kfree(work);

no_disc:
        rio_init();

        return 0;
}

device_initcall_sync(rio_init_mports);

static int hdids[RIO_MAX_MPORTS + 1];

static int rio_get_hdid(int index)
{
        if (!hdids[0] || hdids[0] <= index || index >= RIO_MAX_MPORTS)
                return -1;

        return hdids[index + 1];
}

static int rio_hdid_setup(char *str)
{
        (void)get_options(str, ARRAY_SIZE(hdids), hdids);
        return 1;
}

__setup("riohdid=", rio_hdid_setup);

int rio_register_mport(struct rio_mport *port)
{
        if (next_portid >= RIO_MAX_MPORTS) {
                pr_err("RIO: reached specified max number of mports\n");
                return 1;
        }

        port->id = next_portid++;
        port->host_deviceid = rio_get_hdid(port->id);
        list_add_tail(&port->node, &rio_mports);
        return 0;
}

EXPORT_SYMBOL_GPL(rio_local_get_device_id);
EXPORT_SYMBOL_GPL(rio_get_device);
EXPORT_SYMBOL_GPL(rio_get_asm);
EXPORT_SYMBOL_GPL(rio_request_inb_dbell);
EXPORT_SYMBOL_GPL(rio_release_inb_dbell);
EXPORT_SYMBOL_GPL(rio_request_outb_dbell);
EXPORT_SYMBOL_GPL(rio_release_outb_dbell);
EXPORT_SYMBOL_GPL(rio_request_inb_mbox);
EXPORT_SYMBOL_GPL(rio_release_inb_mbox);
EXPORT_SYMBOL_GPL(rio_request_outb_mbox);
EXPORT_SYMBOL_GPL(rio_release_outb_mbox);