/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 *
 * This 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.
 *
 * This is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

#include "usbip_common.h"
#include "stub.h"


static void stub_free_priv_and_urb(struct stub_priv *priv)
{
        struct urb *urb = priv->urb;

        kfree(urb->setup_packet);
        kfree(urb->transfer_buffer);
        list_del(&priv->list);
        kmem_cache_free(stub_priv_cache, priv);
        usb_free_urb(urb);
}

/* be in spin_lock_irqsave(&sdev->priv_lock, flags) */
void stub_enqueue_ret_unlink(struct stub_device *sdev, __u32 seqnum,
                             __u32 status)
{
        struct stub_unlink *unlink;

        unlink = kzalloc(sizeof(struct stub_unlink), GFP_ATOMIC);
        if (!unlink) {
                dev_err(&sdev->interface->dev, "alloc stub_unlink\n");
                usbip_event_add(&sdev->ud, VDEV_EVENT_ERROR_MALLOC);
                return;
        }

        unlink->seqnum = seqnum;
        unlink->status = status;

        list_add_tail(&unlink->list, &sdev->unlink_tx);
}

/**
 * stub_complete - completion handler of a usbip urb
 * @urb: pointer to the urb completed
 * @regs:
 *
 * When a urb has completed, the USB core driver calls this function mostly in
 * the interrupt context. To return the result of a urb, the completed urb is
 * linked to the pending list of returning.
 *
 */
void stub_complete(struct urb *urb)
{
        struct stub_priv *priv = (struct stub_priv *) urb->context;
        struct stub_device *sdev = priv->sdev;
        unsigned long flags;

        dbg_stub_tx("complete! status %d\n", urb->status);


        switch (urb->status) {
        case 0:
                /* OK */
                break;
        case -ENOENT:
                uinfo("stopped by a call of usb_kill_urb() because of"
                                        "cleaning up a virtual connection\n");
                return;
        case -ECONNRESET:
                uinfo("unlinked by a call of usb_unlink_urb()\n");
                break;
        case -EPIPE:
                uinfo("endpoint %d is stalled\n", usb_pipeendpoint(urb->pipe));
                break;
        case -ESHUTDOWN:
                uinfo("device removed?\n");
                break;
        default:
                uinfo("urb completion with non-zero status %d\n", urb->status);
        }

        /* link a urb to the queue of tx. */
        spin_lock_irqsave(&sdev->priv_lock, flags);

        if (priv->unlinking) {
                stub_enqueue_ret_unlink(sdev, priv->seqnum, urb->status);
                stub_free_priv_and_urb(priv);
        } else
                list_move_tail(&priv->list, &sdev->priv_tx);


        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        /* wake up tx_thread */
        wake_up(&sdev->tx_waitq);
}


/*-------------------------------------------------------------------------*/
/* fill PDU */

static inline void setup_base_pdu(struct usbip_header_basic *base,
                __u32 command, __u32 seqnum)
{
        base->command = command;
        base->seqnum  = seqnum;
        base->devid   = 0;
        base->ep      = 0;
        base->direction   = 0;
}

static void setup_ret_submit_pdu(struct usbip_header *rpdu, struct urb *urb)
{
        struct stub_priv *priv = (struct stub_priv *) urb->context;

        setup_base_pdu(&rpdu->base, USBIP_RET_SUBMIT, priv->seqnum);

        usbip_pack_pdu(rpdu, urb, USBIP_RET_SUBMIT, 1);
}

static void setup_ret_unlink_pdu(struct usbip_header *rpdu,
                struct stub_unlink *unlink)
{
        setup_base_pdu(&rpdu->base, USBIP_RET_UNLINK, unlink->seqnum);

        rpdu->u.ret_unlink.status = unlink->status;
}


/*-------------------------------------------------------------------------*/
/* send RET_SUBMIT */

static struct stub_priv *dequeue_from_priv_tx(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_priv *priv, *tmp;

        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry_safe(priv, tmp, &sdev->priv_tx, list) {
                list_move_tail(&priv->list, &sdev->priv_free);
                spin_unlock_irqrestore(&sdev->priv_lock, flags);
                return priv;
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return NULL;
}

static int stub_send_ret_submit(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_priv *priv, *tmp;

        struct msghdr msg;
        struct kvec iov[3];
        size_t txsize;

        size_t total_size = 0;

        while ((priv = dequeue_from_priv_tx(sdev)) != NULL) {
                int ret;
                struct urb *urb = priv->urb;
                struct usbip_header pdu_header;
                void *iso_buffer = NULL;

                txsize = 0;
                memset(&pdu_header, 0, sizeof(pdu_header));
                memset(&msg, 0, sizeof(msg));
                memset(&iov, 0, sizeof(iov));

                dbg_stub_tx("setup txdata urb %p\n", urb);


                /* 1. setup usbip_header */
                setup_ret_submit_pdu(&pdu_header, urb);
                usbip_header_correct_endian(&pdu_header, 1);

                iov[0].iov_base = &pdu_header;
                iov[0].iov_len  = sizeof(pdu_header);
                txsize += sizeof(pdu_header);

                /* 2. setup transfer buffer */
                if (usb_pipein(urb->pipe) && urb->actual_length > 0) {
                        iov[1].iov_base = urb->transfer_buffer;
                        iov[1].iov_len  = urb->actual_length;
                        txsize += urb->actual_length;
                }

                /* 3. setup iso_packet_descriptor */
                if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
                        ssize_t len = 0;

                        iso_buffer = usbip_alloc_iso_desc_pdu(urb, &len);
                        if (!iso_buffer) {
                                usbip_event_add(&sdev->ud,
                                                SDEV_EVENT_ERROR_MALLOC);
                                return -1;
                        }

                        iov[2].iov_base = iso_buffer;
                        iov[2].iov_len  = len;
                        txsize += len;
                }

                ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, iov,
                                     3, txsize);
                if (ret != txsize) {
                        dev_err(&sdev->interface->dev,
                                "sendmsg failed!, retval %d for %zd\n",
                                ret, txsize);
                        kfree(iso_buffer);
                        usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
                        return -1;
                }

                kfree(iso_buffer);
                dbg_stub_tx("send txdata\n");

                total_size += txsize;
        }


        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry_safe(priv, tmp, &sdev->priv_free, list) {
                stub_free_priv_and_urb(priv);
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return total_size;
}


/*-------------------------------------------------------------------------*/
/* send RET_UNLINK */

static struct stub_unlink *dequeue_from_unlink_tx(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_unlink *unlink, *tmp;

        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry_safe(unlink, tmp, &sdev->unlink_tx, list) {
                list_move_tail(&unlink->list, &sdev->unlink_free);
                spin_unlock_irqrestore(&sdev->priv_lock, flags);
                return unlink;
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return NULL;
}


static int stub_send_ret_unlink(struct stub_device *sdev)
{
        unsigned long flags;
        struct stub_unlink *unlink, *tmp;

        struct msghdr msg;
        struct kvec iov[1];
        size_t txsize;

        size_t total_size = 0;

        while ((unlink = dequeue_from_unlink_tx(sdev)) != NULL) {
                int ret;
                struct usbip_header pdu_header;

                txsize = 0;
                memset(&pdu_header, 0, sizeof(pdu_header));
                memset(&msg, 0, sizeof(msg));
                memset(&iov, 0, sizeof(iov));

                dbg_stub_tx("setup ret unlink %lu\n", unlink->seqnum);

                /* 1. setup usbip_header */
                setup_ret_unlink_pdu(&pdu_header, unlink);
                usbip_header_correct_endian(&pdu_header, 1);

                iov[0].iov_base = &pdu_header;
                iov[0].iov_len  = sizeof(pdu_header);
                txsize += sizeof(pdu_header);

                ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, iov,
                                     1, txsize);
                if (ret != txsize) {
                        dev_err(&sdev->interface->dev,
                                "sendmsg failed!, retval %d for %zd\n",
                                ret, txsize);
                        usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
                        return -1;
                }


                dbg_stub_tx("send txdata\n");

                total_size += txsize;
        }


        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry_safe(unlink, tmp, &sdev->unlink_free, list) {
                list_del(&unlink->list);
                kfree(unlink);
        }

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return total_size;
}


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

void stub_tx_loop(struct usbip_task *ut)
{
        struct usbip_device *ud = container_of(ut, struct usbip_device, tcp_tx);
        struct stub_device *sdev = container_of(ud, struct stub_device, ud);

        while (1) {
                if (signal_pending(current)) {
                        dbg_stub_tx("signal catched\n");
                        break;
                }

                if (usbip_event_happend(ud))
                        break;

                /*
                 * send_ret_submit comes earlier than send_ret_unlink.  stub_rx
                 * looks at only priv_init queue. If the completion of a URB is
                 * earlier than the receive of CMD_UNLINK, priv is moved to
                 * priv_tx queue and stub_rx does not find the target priv. In
                 * this case, vhci_rx receives the result of the submit request
                 * and then receives the result of the unlink request. The
                 * result of the submit is given back to the usbcore as the
                 * completion of the unlink request. The request of the
                 * unlink is ignored. This is ok because a driver who calls
                 * usb_unlink_urb() understands the unlink was too late by
                 * getting the status of the given-backed URB which has the
                 * status of usb_submit_urb().
                 */
                if (stub_send_ret_submit(sdev) < 0)
                        break;

                if (stub_send_ret_unlink(sdev) < 0)
                        break;

                wait_event_interruptible(sdev->tx_waitq,
                                (!list_empty(&sdev->priv_tx) ||
                                 !list_empty(&sdev->unlink_tx)));
        }
}