/*
 * Intel Wireless WiMAX Connection 2400m
 * USB specific TX handling
 *
 *
 * Copyright (C) 2007-2008 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Intel Corporation <linux-wimax@intel.com>
 * Yanir Lubetkin <yanirx.lubetkin@intel.com>
 *  - Initial implementation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *  - Split transport/device specific
 *
 *
 * Takes the TX messages in the i2400m's driver TX FIFO and sends them
 * to the device until there are no more.
 *
 * If we fail sending the message, we just drop it. There isn't much
 * we can do at this point. We could also retry, but the USB stack has
 * already retried and still failed, so there is not much of a
 * point. As well, most of the traffic is network, which has recovery
 * methods for dropped packets.
 *
 * For sending we just obtain a FIFO buffer to send, send it to the
 * USB bulk out, tell the TX FIFO code we have sent it; query for
 * another one, etc... until done.
 *
 * We use a thread so we can call usb_autopm_enable() and
 * usb_autopm_disable() for each transaction; this way when the device
 * goes idle, it will suspend. It also has less overhead than a
 * dedicated workqueue, as it is being used for a single task.
 *
 * ROADMAP
 *
 * i2400mu_tx_setup()
 * i2400mu_tx_release()
 *
 * i2400mu_bus_tx_kick()        - Called by the tx.c code when there
 *                                is new data in the FIFO.
 * i2400mu_txd()
 *   i2400m_tx_msg_get()
 *   i2400m_tx_msg_sent()
 */
#include "i2400m-usb.h"


#define D_SUBMODULE tx
#include "usb-debug-levels.h"


/*
 * Get the next TX message in the TX FIFO and send it to the device
 *
 * Note that any iteration consumes a message to be sent, no matter if
 * it succeeds or fails (we have no real way to retry or complain).
 *
 * Return: 0 if ok, < 0 errno code on hard error.
 */
static
int i2400mu_tx(struct i2400mu *i2400mu, struct i2400m_msg_hdr *tx_msg,
               size_t tx_msg_size)
{
        int result = 0;
        struct i2400m *i2400m = &i2400mu->i2400m;
        struct device *dev = &i2400mu->usb_iface->dev;
        int usb_pipe, sent_size, do_autopm;
        struct usb_endpoint_descriptor *epd;

        d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
        do_autopm = atomic_read(&i2400mu->do_autopm);
        result = do_autopm ?
                usb_autopm_get_interface(i2400mu->usb_iface) : 0;
        if (result < 0) {
                dev_err(dev, "TX: can't get autopm: %d\n", result);
                do_autopm = 0;
        }
        epd = usb_get_epd(i2400mu->usb_iface, i2400mu->endpoint_cfg.bulk_out);
        usb_pipe = usb_sndbulkpipe(i2400mu->usb_dev, epd->bEndpointAddress);
retry:
        result = usb_bulk_msg(i2400mu->usb_dev, usb_pipe,
                              tx_msg, tx_msg_size, &sent_size, 200);
        usb_mark_last_busy(i2400mu->usb_dev);
        switch (result) {
        case 0:
                if (sent_size != tx_msg_size) { /* Too short? drop it */
                        dev_err(dev, "TX: short write (%d B vs %zu "
                                "expected)\n", sent_size, tx_msg_size);
                        result = -EIO;
                }
                break;
        case -EPIPE:
                /*
                 * Stall -- maybe the device is choking with our
                 * requests. Clear it and give it some time. If they
                 * happen to often, it might be another symptom, so we
                 * reset.
                 *
                 * No error handling for usb_clear_halt(0; if it
                 * works, the retry works; if it fails, this switch
                 * does the error handling for us.
                 */
                if (edc_inc(&i2400mu->urb_edc,
                            10 * EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME)) {
                        dev_err(dev, "BM-CMD: too many stalls in "
                                "URB; resetting device\n");
                        usb_queue_reset_device(i2400mu->usb_iface);
                        /* fallthrough */
                } else {
                        usb_clear_halt(i2400mu->usb_dev, usb_pipe);
                        msleep(10);     /* give the device some time */
                        goto retry;
                }
        case -EINVAL:                   /* while removing driver */
        case -ENODEV:                   /* dev disconnect ... */
        case -ENOENT:                   /* just ignore it */
        case -ESHUTDOWN:                /* and exit */
        case -ECONNRESET:
                result = -ESHUTDOWN;
                break;
        default:                        /* Some error? */
                if (edc_inc(&i2400mu->urb_edc,
                            EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME)) {
                        dev_err(dev, "TX: maximum errors in URB "
                                "exceeded; resetting device\n");
                        usb_queue_reset_device(i2400mu->usb_iface);
                } else {
                        dev_err(dev, "TX: cannot send URB; retrying. "
                                "tx_msg @%zu %zu B [%d sent]: %d\n",
                                (void *) tx_msg - i2400m->tx_buf,
                                tx_msg_size, sent_size, result);
                        goto retry;
                }
        }
        if (do_autopm)
                usb_autopm_put_interface(i2400mu->usb_iface);
        d_fnend(4, dev, "(i2400mu %p) = result\n", i2400mu);
        return result;
}


/*
 * Get the next TX message in the TX FIFO and send it to the device
 *
 * Note we exit the loop if i2400mu_tx() fails; that function only
 * fails on hard error (failing to tx a buffer not being one of them,
 * see its doc).
 *
 * Return: 0
 */
static
int i2400mu_txd(void *_i2400mu)
{
        struct i2400mu *i2400mu = _i2400mu;
        struct i2400m *i2400m = &i2400mu->i2400m;
        struct device *dev = &i2400mu->usb_iface->dev;
        struct i2400m_msg_hdr *tx_msg;
        size_t tx_msg_size;
        unsigned long flags;

        d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);

        spin_lock_irqsave(&i2400m->tx_lock, flags);
        BUG_ON(i2400mu->tx_kthread != NULL);
        i2400mu->tx_kthread = current;
        spin_unlock_irqrestore(&i2400m->tx_lock, flags);

        while (1) {
                d_printf(2, dev, "TX: waiting for messages\n");
                tx_msg = NULL;
                wait_event_interruptible(
                        i2400mu->tx_wq,
                        (kthread_should_stop()  /* check this first! */
                         || (tx_msg = i2400m_tx_msg_get(i2400m, &tx_msg_size)))
                        );
                if (kthread_should_stop())
                        break;
                WARN_ON(tx_msg == NULL);        /* should not happen...*/
                d_printf(2, dev, "TX: submitting %zu bytes\n", tx_msg_size);
                d_dump(5, dev, tx_msg, tx_msg_size);
                /* Yeah, we ignore errors ... not much we can do */
                i2400mu_tx(i2400mu, tx_msg, tx_msg_size);
                i2400m_tx_msg_sent(i2400m);     /* ack it, advance the FIFO */
        }

        spin_lock_irqsave(&i2400m->tx_lock, flags);
        i2400mu->tx_kthread = NULL;
        spin_unlock_irqrestore(&i2400m->tx_lock, flags);

        d_fnend(4, dev, "(i2400mu %p)\n", i2400mu);
        return 0;
}


/*
 * i2400m TX engine notifies us that there is data in the FIFO ready
 * for TX
 *
 * If there is a URB in flight, don't do anything; when it finishes,
 * it will see there is data in the FIFO and send it. Else, just
 * submit a write.
 */
void i2400mu_bus_tx_kick(struct i2400m *i2400m)
{
        struct i2400mu *i2400mu = container_of(i2400m, struct i2400mu, i2400m);
        struct device *dev = &i2400mu->usb_iface->dev;

        d_fnstart(3, dev, "(i2400m %p) = void\n", i2400m);
        wake_up_all(&i2400mu->tx_wq);
        d_fnend(3, dev, "(i2400m %p) = void\n", i2400m);
}


int i2400mu_tx_setup(struct i2400mu *i2400mu)
{
        int result = 0;
        struct i2400m *i2400m = &i2400mu->i2400m;
        struct device *dev = &i2400mu->usb_iface->dev;
        struct wimax_dev *wimax_dev = &i2400m->wimax_dev;
        struct task_struct *kthread;

        kthread = kthread_run(i2400mu_txd, i2400mu, "%s-tx",
                              wimax_dev->name);
        /* the kthread function sets i2400mu->tx_thread */
        if (IS_ERR(kthread)) {
                result = PTR_ERR(kthread);
                dev_err(dev, "TX: cannot start thread: %d\n", result);
        }
        return result;
}

void i2400mu_tx_release(struct i2400mu *i2400mu)
{
        unsigned long flags;
        struct i2400m *i2400m = &i2400mu->i2400m;
        struct device *dev = i2400m_dev(i2400m);
        struct task_struct *kthread;

        spin_lock_irqsave(&i2400m->tx_lock, flags);
        kthread = i2400mu->tx_kthread;
        i2400mu->tx_kthread = NULL;
        spin_unlock_irqrestore(&i2400m->tx_lock, flags);
        if (kthread)
                kthread_stop(kthread);
        else
                d_printf(1, dev, "TX: kthread had already exited\n");
}