/*
 * Intel Wireless WiMAX Connection 2400m over USB
 * Notification 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>
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *  - Initial implementation
 *
 *
 * The notification endpoint is active when the device is not in boot
 * mode; in here we just read and get notifications; based on those,
 * we act to either reinitialize the device after a reboot or to
 * submit a RX request.
 *
 * ROADMAP
 *
 * i2400mu_usb_notification_setup()
 *
 * i2400mu_usb_notification_release()
 *
 * i2400mu_usb_notification_cb()        Called when a URB is ready
 *   i2400mu_notif_grok()
 *     i2400m_is_boot_barker()
 *     i2400m_dev_reset_handle()
 *     i2400mu_rx_kick()
 */
#include <linux/usb.h>
#include <linux/slab.h>
#include "i2400m-usb.h"


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


static const
__le32 i2400m_ZERO_BARKER[4] = { 0, 0, 0, 0 };


/*
 * Process a received notification
 *
 * In normal operation mode, we can only receive two types of payloads
 * on the notification endpoint:
 *
 *   - a reboot barker, we do a bootstrap (the device has reseted).
 *
 *   - a block of zeroes: there is pending data in the IN endpoint
 */
static
int i2400mu_notification_grok(struct i2400mu *i2400mu, const void *buf,
                                 size_t buf_len)
{
        int ret;
        struct device *dev = &i2400mu->usb_iface->dev;
        struct i2400m *i2400m = &i2400mu->i2400m;

        d_fnstart(4, dev, "(i2400m %p buf %p buf_len %zu)\n",
                  i2400mu, buf, buf_len);
        ret = -EIO;
        if (buf_len < sizeof(i2400m_ZERO_BARKER))
                /* Not a bug, just ignore */
                goto error_bad_size;
        ret = 0;
        if (!memcmp(i2400m_ZERO_BARKER, buf, sizeof(i2400m_ZERO_BARKER))) {
                i2400mu_rx_kick(i2400mu);
                goto out;
        }
        ret = i2400m_is_boot_barker(i2400m, buf, buf_len);
        if (unlikely(ret >= 0))
                ret = i2400m_dev_reset_handle(i2400m, "device rebooted");
        else    /* Unknown or unexpected data in the notif message */
                i2400m_unknown_barker(i2400m, buf, buf_len);
error_bad_size:
out:
        d_fnend(4, dev, "(i2400m %p buf %p buf_len %zu) = %d\n",
                i2400mu, buf, buf_len, ret);
        return ret;
}


/*
 * URB callback for the notification endpoint
 *
 * @urb: the urb received from the notification endpoint
 *
 * This function will just process the USB side of the transaction,
 * checking everything is fine, pass the processing to
 * i2400m_notification_grok() and resubmit the URB.
 */
static
void i2400mu_notification_cb(struct urb *urb)
{
        int ret;
        struct i2400mu *i2400mu = urb->context;
        struct device *dev = &i2400mu->usb_iface->dev;

        d_fnstart(4, dev, "(urb %p status %d actual_length %d)\n",
                  urb, urb->status, urb->actual_length);
        ret = urb->status;
        switch (ret) {
        case 0:
                ret = i2400mu_notification_grok(i2400mu, urb->transfer_buffer,
                                                urb->actual_length);
                if (ret == -EIO && edc_inc(&i2400mu->urb_edc, EDC_MAX_ERRORS,
                                           EDC_ERROR_TIMEFRAME))
                        goto error_exceeded;
                if (ret == -ENOMEM)     /* uff...power cycle? shutdown? */
                        goto error_exceeded;
                break;
        case -EINVAL:                   /* while removing driver */
        case -ENODEV:                   /* dev disconnect ... */
        case -ENOENT:                   /* ditto */
        case -ESHUTDOWN:                /* URB killed */
        case -ECONNRESET:               /* disconnection */
                goto out;               /* Notify around */
        default:                        /* Some error? */
                if (edc_inc(&i2400mu->urb_edc,
                            EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME))
                        goto error_exceeded;
                dev_err(dev, "notification: URB error %d, retrying\n",
                        urb->status);
        }
        usb_mark_last_busy(i2400mu->usb_dev);
        ret = usb_submit_urb(i2400mu->notif_urb, GFP_ATOMIC);
        switch (ret) {
        case 0:
        case -EINVAL:                   /* while removing driver */
        case -ENODEV:                   /* dev disconnect ... */
        case -ENOENT:                   /* ditto */
        case -ESHUTDOWN:                /* URB killed */
        case -ECONNRESET:               /* disconnection */
                break;                  /* just ignore */
        default:                        /* Some error? */
                dev_err(dev, "notification: cannot submit URB: %d\n", ret);
                goto error_submit;
        }
        d_fnend(4, dev, "(urb %p status %d actual_length %d) = void\n",
                urb, urb->status, urb->actual_length);
        return;

error_exceeded:
        dev_err(dev, "maximum errors in notification URB exceeded; "
                "resetting device\n");
error_submit:
        usb_queue_reset_device(i2400mu->usb_iface);
out:
        d_fnend(4, dev, "(urb %p status %d actual_length %d) = void\n",
                urb, urb->status, urb->actual_length);
}


/*
 * setup the notification endpoint
 *
 * @i2400m: device descriptor
 *
 * This procedure prepares the notification urb and handler for receiving
 * unsolicited barkers from the device.
 */
int i2400mu_notification_setup(struct i2400mu *i2400mu)
{
        struct device *dev = &i2400mu->usb_iface->dev;
        int usb_pipe, ret = 0;
        struct usb_endpoint_descriptor *epd;
        char *buf;

        d_fnstart(4, dev, "(i2400m %p)\n", i2400mu);
        buf = kmalloc(I2400MU_MAX_NOTIFICATION_LEN, GFP_KERNEL | GFP_DMA);
        if (buf == NULL) {
                ret = -ENOMEM;
                goto error_buf_alloc;
        }

        i2400mu->notif_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!i2400mu->notif_urb) {
                ret = -ENOMEM;
                goto error_alloc_urb;
        }
        epd = usb_get_epd(i2400mu->usb_iface,
                          i2400mu->endpoint_cfg.notification);
        usb_pipe = usb_rcvintpipe(i2400mu->usb_dev, epd->bEndpointAddress);
        usb_fill_int_urb(i2400mu->notif_urb, i2400mu->usb_dev, usb_pipe,
                         buf, I2400MU_MAX_NOTIFICATION_LEN,
                         i2400mu_notification_cb, i2400mu, epd->bInterval);
        ret = usb_submit_urb(i2400mu->notif_urb, GFP_KERNEL);
        if (ret != 0) {
                dev_err(dev, "notification: cannot submit URB: %d\n", ret);
                goto error_submit;
        }
        d_fnend(4, dev, "(i2400m %p) = %d\n", i2400mu, ret);
        return ret;

error_submit:
        usb_free_urb(i2400mu->notif_urb);
error_alloc_urb:
        kfree(buf);
error_buf_alloc:
        d_fnend(4, dev, "(i2400m %p) = %d\n", i2400mu, ret);
        return ret;
}


/*
 * Tear down of the notification mechanism
 *
 * @i2400m: device descriptor
 *
 * Kill the interrupt endpoint urb, free any allocated resources.
 *
 * We need to check if we have done it before as for example,
 * _suspend() call this; if after a suspend() we get a _disconnect()
 * (as the case is when hibernating), nothing bad happens.
 */
void i2400mu_notification_release(struct i2400mu *i2400mu)
{
        struct device *dev = &i2400mu->usb_iface->dev;

        d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
        if (i2400mu->notif_urb != NULL) {
                usb_kill_urb(i2400mu->notif_urb);
                kfree(i2400mu->notif_urb->transfer_buffer);
                usb_free_urb(i2400mu->notif_urb);
                i2400mu->notif_urb = NULL;
        }
        d_fnend(4, dev, "(i2400mu %p)\n", i2400mu);
}