i2400m/USB: TX and RX path backends

Implements the backend so that the generic driver can TX/RX to/from
the USB device.

TX is implemented with a kthread sitting in a never-ending loop that
when kicked by the generic driver's TX code will pull data from the TX
FIFO and send it to the device until it drains it. Then it goes back
sleep, waiting for another kick.

RX is implemented in a similar fashion, but reads are kicked in by the
device notifying in the interrupt endpoint that data is ready. Device
reset notifications are also sent via the notification endpoint.

We need a thread contexts to run USB autopm functions (blocking) and
to process the received data (can get to be heavy in processing
time).

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/net/wimax/i2400m/usb-notif.c

@@ -0,0 +1,269 @@
+/*
+ * 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_dev_reset_handle()
+ *     i2400mu_rx_kick()
+ */
+#include <linux/usb.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_NBOOT_BARKER))
+		/* Not a bug, just ignore */
+		goto error_bad_size;
+	if (!memcmp(i2400m_NBOOT_BARKER, buf, sizeof(i2400m_NBOOT_BARKER))
+	    || !memcmp(i2400m_SBOOT_BARKER, buf, sizeof(i2400m_SBOOT_BARKER)))
+		ret = i2400m_dev_reset_handle(i2400m);
+	else if (!memcmp(i2400m_ZERO_BARKER, buf, sizeof(i2400m_ZERO_BARKER))) {
+		i2400mu_rx_kick(i2400mu);
+		ret = 0;
+	} else {	/* Unknown or unexpected data in the notif message */
+		char prefix[64];
+		ret = -EIO;
+		dev_err(dev, "HW BUG? Unknown/unexpected data in notification "
+			"message (%zu bytes)\n", buf_len);
+		snprintf(prefix, sizeof(prefix), "%s %s: ",
+			 dev_driver_string(dev) , dev->bus_id);
+		if (buf_len > 64) {
+			print_hex_dump(KERN_ERR, prefix, DUMP_PREFIX_OFFSET,
+				       8, 4, buf, 64, 0);
+			printk(KERN_ERR "%s... (only first 64 bytes "
+			       "dumped)\n", prefix);
+		} else
+			print_hex_dump(KERN_ERR, prefix, DUMP_PREFIX_OFFSET,
+				       8, 4, buf, buf_len, 0);
+	}
+error_bad_size:
+	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);
+	return;
+}
+
+
+/*
+ * 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) {
+		dev_err(dev, "notification: buffer allocation failed\n");
+		ret = -ENOMEM;
+		goto error_buf_alloc;
+	}
+
+	i2400mu->notif_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!i2400mu->notif_urb) {
+		ret = -ENOMEM;
+		dev_err(dev, "notification: cannot allocate URB\n");
+		goto error_alloc_urb;
+	}
+	epd = usb_get_epd(i2400mu->usb_iface, I2400MU_EP_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);
+}

drivers/net/wimax/i2400m/usb-rx.c

@@ -0,0 +1,417 @@
+/*
+ * Intel Wireless WiMAX Connection 2400m
+ * USB RX 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>
+ *  - Use skb_clone(), break up processing in chunks
+ *  - Split transport/device specific
+ *  - Make buffer size dynamic to exert less memory pressure
+ *
+ *
+ * This handles the RX path on USB.
+ *
+ * When a notification is received that says 'there is RX data ready',
+ * we call i2400mu_rx_kick(); that wakes up the RX kthread, which
+ * reads a buffer from USB and passes it to i2400m_rx() in the generic
+ * handling code. The RX buffer has an specific format that is
+ * described in rx.c.
+ *
+ * We use a kernel thread in a loop because:
+ *
+ *  - we want to be able to call the USB power management get/put
+ *    functions (blocking) before each transaction.
+ *
+ *  - We might get a lot of notifications and we don't want to submit
+ *    a zillion reads; by serializing, we are throttling.
+ *
+ *  - RX data processing can get heavy enough so that it is not
+ *    appropiate for doing it in the USB callback; thus we run it in a
+ *    process context.
+ *
+ * We provide a read buffer of an arbitrary size (short of a page); if
+ * the callback reports -EOVERFLOW, it means it was too small, so we
+ * just double the size and retry (being careful to append, as
+ * sometimes the device provided some data). Every now and then we
+ * check if the average packet size is smaller than the current packet
+ * size and if so, we halve it. At the end, the size of the
+ * preallocated buffer should be following the average received
+ * transaction size, adapting dynamically to it.
+ *
+ * ROADMAP
+ *
+ * i2400mu_rx_kick()		   Called from notif.c when we get a
+ *   			           'data ready' notification
+ * i2400mu_rxd()                   Kernel RX daemon
+ *   i2400mu_rx()                  Receive USB data
+ *   i2400m_rx()                   Send data to generic i2400m RX handling
+ *
+ * i2400mu_rx_setup()              called from i2400mu_bus_dev_start()
+ *
+ * i2400mu_rx_release()            called from i2400mu_bus_dev_stop()
+ */
+#include <linux/workqueue.h>
+#include <linux/usb.h>
+#include "i2400m-usb.h"
+
+
+#define D_SUBMODULE rx
+#include "usb-debug-levels.h"
+
+/*
+ * Dynamic RX size
+ *
+ * We can't let the rx_size be a multiple of 512 bytes (the RX
+ * endpoint's max packet size). On some USB host controllers (we
+ * haven't been able to fully characterize which), if the device is
+ * about to send (for example) X bytes and we only post a buffer to
+ * receive n*512, it will fail to mark that as babble (so that
+ * i2400mu_rx() [case -EOVERFLOW] can resize the buffer and get the
+ * rest).
+ *
+ * So on growing or shrinking, if it is a multiple of the
+ * maxpacketsize, we remove some (instead of incresing some, so in a
+ * buddy allocator we try to waste less space).
+ *
+ * Note we also need a hook for this on i2400mu_rx() -- when we do the
+ * first read, we are sure we won't hit this spot because
+ * i240mm->rx_size has been set properly. However, if we have to
+ * double because of -EOVERFLOW, when we launch the read to get the
+ * rest of the data, we *have* to make sure that also is not a
+ * multiple of the max_pkt_size.
+ */
+
+static
+size_t i2400mu_rx_size_grow(struct i2400mu *i2400mu)
+{
+	struct device *dev = &i2400mu->usb_iface->dev;
+	size_t rx_size;
+	const size_t max_pkt_size = 512;
+
+	rx_size = 2 * i2400mu->rx_size;
+	if (rx_size % max_pkt_size == 0) {
+		rx_size -= 8;
+		d_printf(1, dev,
+			 "RX: expected size grew to %zu [adjusted -8] "
+			 "from %zu\n",
+			 rx_size, i2400mu->rx_size);
+	} else
+		d_printf(1, dev,
+			 "RX: expected size grew to %zu from %zu\n",
+			 rx_size, i2400mu->rx_size);
+	return rx_size;
+}
+
+
+static
+void i2400mu_rx_size_maybe_shrink(struct i2400mu *i2400mu)
+{
+	const size_t max_pkt_size = 512;
+	struct device *dev = &i2400mu->usb_iface->dev;
+
+	if (unlikely(i2400mu->rx_size_cnt >= 100
+		     && i2400mu->rx_size_auto_shrink)) {
+		size_t avg_rx_size =
+			i2400mu->rx_size_acc / i2400mu->rx_size_cnt;
+		size_t new_rx_size = i2400mu->rx_size / 2;
+		if (avg_rx_size < new_rx_size) {
+			if (new_rx_size % max_pkt_size == 0) {
+				new_rx_size -= 8;
+				d_printf(1, dev,
+					 "RX: expected size shrank to %zu "
+					 "[adjusted -8] from %zu\n",
+					 new_rx_size, i2400mu->rx_size);
+			} else
+				d_printf(1, dev,
+					 "RX: expected size shrank to %zu "
+					 "from %zu\n",
+					 new_rx_size, i2400mu->rx_size);
+			i2400mu->rx_size = new_rx_size;
+			i2400mu->rx_size_cnt = 0;
+			i2400mu->rx_size_acc = i2400mu->rx_size;
+		}
+	}
+}
+
+/*
+ * Receive a message with payloads from the USB bus into an skb
+ *
+ * @i2400mu: USB device descriptor
+ * @rx_skb: skb where to place the received message
+ *
+ * Deals with all the USB-specifics of receiving, dynamically
+ * increasing the buffer size if so needed. Returns the payload in the
+ * skb, ready to process. On a zero-length packet, we retry.
+ *
+ * On soft USB errors, we retry (until they become too frequent and
+ * then are promoted to hard); on hard USB errors, we reset the
+ * device. On other errors (skb realloacation, we just drop it and
+ * hope for the next invocation to solve it).
+ *
+ * Returns: pointer to the skb if ok, ERR_PTR on error.
+ *   NOTE: this function might realloc the skb (if it is too small),
+ *   so always update with the one returned.
+ *   ERR_PTR() is < 0 on error.
+ */
+static
+struct sk_buff *i2400mu_rx(struct i2400mu *i2400mu, struct sk_buff *rx_skb)
+{
+	int result = 0;
+	struct device *dev = &i2400mu->usb_iface->dev;
+	int usb_pipe, read_size, rx_size, do_autopm;
+	struct usb_endpoint_descriptor *epd;
+	const size_t max_pkt_size = 512;
+
+	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, "RX: can't get autopm: %d\n", result);
+		do_autopm = 0;
+	}
+	epd = usb_get_epd(i2400mu->usb_iface, I2400MU_EP_BULK_IN);
+	usb_pipe = usb_rcvbulkpipe(i2400mu->usb_dev, epd->bEndpointAddress);
+retry:
+	rx_size = skb_end_pointer(rx_skb) - rx_skb->data - rx_skb->len;
+	if (unlikely(rx_size % max_pkt_size == 0)) {
+		rx_size -= 8;
+		d_printf(1, dev, "RX: rx_size adapted to %d [-8]\n", rx_size);
+	}
+	result = usb_bulk_msg(
+		i2400mu->usb_dev, usb_pipe, rx_skb->data + rx_skb->len,
+		rx_size, &read_size, HZ);
+	usb_mark_last_busy(i2400mu->usb_dev);
+	switch (result) {
+	case 0:
+		if (read_size == 0)
+			goto retry;	/* ZLP, just resubmit */
+		skb_put(rx_skb, read_size);
+		break;
+	case -EINVAL:			/* while removing driver */
+	case -ENODEV:			/* dev disconnect ... */
+	case -ENOENT:			/* just ignore it */
+	case -ESHUTDOWN:
+	case -ECONNRESET:
+		break;
+	case -EOVERFLOW: {		/* too small, reallocate */
+		struct sk_buff *new_skb;
+		rx_size = i2400mu_rx_size_grow(i2400mu);
+		if (rx_size <= (1 << 16))	/* cap it */
+			i2400mu->rx_size = rx_size;
+		else if (printk_ratelimit()) {
+			dev_err(dev, "BUG? rx_size up to %d\n", rx_size);
+			result = -EINVAL;
+			goto out;
+		}
+		skb_put(rx_skb, read_size);
+		new_skb = skb_copy_expand(rx_skb, 0, rx_size - rx_skb->len,
+					  GFP_KERNEL);
+		if (new_skb == NULL) {
+			if (printk_ratelimit())
+				dev_err(dev, "RX: Can't reallocate skb to %d; "
+					"RX dropped\n", rx_size);
+			kfree(rx_skb);
+			result = 0;
+			goto out;	/* drop it...*/
+		}
+		kfree_skb(rx_skb);
+		rx_skb = new_skb;
+		i2400mu->rx_size_cnt = 0;
+		i2400mu->rx_size_acc = i2400mu->rx_size;
+		d_printf(1, dev, "RX: size changed to %d, received %d, "
+			 "copied %d, capacity %ld\n",
+			 rx_size, read_size, rx_skb->len,
+			 (long) (skb_end_pointer(new_skb) - new_skb->head));
+		goto retry;
+	}
+		/* In most cases, it happens due to the hardware scheduling a
+		 * read when there was no data - unfortunately, we have no way
+		 * to tell this timeout from a USB timeout. So we just ignore
+		 * it. */
+	case -ETIMEDOUT:
+		dev_err(dev, "RX: timeout: %d\n", result);
+		result = 0;
+		break;
+	default:			/* Any error */
+		if (edc_inc(&i2400mu->urb_edc,
+			    EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME))
+			goto error_reset;
+		dev_err(dev, "RX: error receiving URB: %d, retrying\n", result);
+		goto retry;
+	}
+out:
+	if (do_autopm)
+		usb_autopm_put_interface(i2400mu->usb_iface);
+	d_fnend(4, dev, "(i2400mu %p) = %p\n", i2400mu, rx_skb);
+	return rx_skb;
+
+error_reset:
+	dev_err(dev, "RX: maximum errors in URB exceeded; "
+		"resetting device\n");
+	usb_queue_reset_device(i2400mu->usb_iface);
+	rx_skb = ERR_PTR(result);
+	goto out;
+}
+
+
+/*
+ * Kernel thread for USB reception of data
+ *
+ * This thread waits for a kick; once kicked, it will allocate an skb
+ * and receive a single message to it from USB (using
+ * i2400mu_rx()). Once received, it is passed to the generic i2400m RX
+ * code for processing.
+ *
+ * When done processing, it runs some dirty statistics to verify if
+ * the last 100 messages received were smaller than half of the
+ * current RX buffer size. In that case, the RX buffer size is
+ * halved. This will helps lowering the pressure on the memory
+ * allocator.
+ *
+ * Hard errors force the thread to exit.
+ */
+static
+int i2400mu_rxd(void *_i2400mu)
+{
+	int result = 0;
+	struct i2400mu *i2400mu = _i2400mu;
+	struct i2400m *i2400m = &i2400mu->i2400m;
+	struct device *dev = &i2400mu->usb_iface->dev;
+	struct net_device *net_dev = i2400m->wimax_dev.net_dev;
+	size_t pending;
+	int rx_size;
+	struct sk_buff *rx_skb;
+
+	d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
+	while (1) {
+		d_printf(2, dev, "TX: waiting for messages\n");
+		pending = 0;
+		wait_event_interruptible(
+			i2400mu->rx_wq,
+			(kthread_should_stop()	/* check this first! */
+			 || (pending = atomic_read(&i2400mu->rx_pending_count)))
+			);
+		if (kthread_should_stop())
+			break;
+		if (pending == 0)
+			continue;
+		rx_size = i2400mu->rx_size;
+		d_printf(2, dev, "RX: reading up to %d bytes\n", rx_size);
+		rx_skb = __netdev_alloc_skb(net_dev, rx_size, GFP_KERNEL);
+		if (rx_skb == NULL) {
+			dev_err(dev, "RX: can't allocate skb [%d bytes]\n",
+				rx_size);
+			msleep(50);	/* give it some time? */
+			continue;
+		}
+
+		/* Receive the message with the payloads */
+		rx_skb = i2400mu_rx(i2400mu, rx_skb);
+		result = PTR_ERR(rx_skb);
+		if (IS_ERR(rx_skb))
+			goto out;
+		atomic_dec(&i2400mu->rx_pending_count);
+		if (rx_skb->len == 0) {	/* some ignorable condition */
+			kfree_skb(rx_skb);
+			continue;
+		}
+
+		/* Deliver the message to the generic i2400m code */
+		i2400mu->rx_size_cnt++;
+		i2400mu->rx_size_acc += rx_skb->len;
+		result = i2400m_rx(i2400m, rx_skb);
+		if (result == -EIO
+		    && edc_inc(&i2400mu->urb_edc,
+			       EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME)) {
+			goto error_reset;
+		}
+
+		/* Maybe adjust RX buffer size */
+		i2400mu_rx_size_maybe_shrink(i2400mu);
+	}
+	result = 0;
+out:
+	d_fnend(4, dev, "(i2400mu %p) = %d\n", i2400mu, result);
+	return result;
+
+error_reset:
+	dev_err(dev, "RX: maximum errors in received buffer exceeded; "
+		"resetting device\n");
+	usb_queue_reset_device(i2400mu->usb_iface);
+	goto out;
+}
+
+
+/*
+ * Start reading from the device
+ *
+ * @i2400m: device instance
+ *
+ * Notify the RX thread that there is data pending.
+ */
+void i2400mu_rx_kick(struct i2400mu *i2400mu)
+{
+	struct i2400m *i2400m = &i2400mu->i2400m;
+	struct device *dev = &i2400mu->usb_iface->dev;
+
+	d_fnstart(3, dev, "(i2400mu %p)\n", i2400m);
+	atomic_inc(&i2400mu->rx_pending_count);
+	wake_up_all(&i2400mu->rx_wq);
+	d_fnend(3, dev, "(i2400m %p) = void\n", i2400m);
+}
+
+
+int i2400mu_rx_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;
+
+	i2400mu->rx_kthread = kthread_run(i2400mu_rxd, i2400mu, "%s-rx",
+					  wimax_dev->name);
+	if (IS_ERR(i2400mu->rx_kthread)) {
+		result = PTR_ERR(i2400mu->rx_kthread);
+		dev_err(dev, "RX: cannot start thread: %d\n", result);
+	}
+	return result;
+}
+
+void i2400mu_rx_release(struct i2400mu *i2400mu)
+{
+	kthread_stop(i2400mu->rx_kthread);
+}
+

drivers/net/wimax/i2400m/usb-tx.c

@@ -0,0 +1,229 @@
+/*
+ * 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_EP_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, HZ);
+	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 -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 funtion 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)
+{
+	int result = 0;
+	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;
+
+	d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
+
+	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 */
+		if (result < 0)
+			break;
+	}
+	d_fnend(4, dev, "(i2400mu %p) = %d\n", i2400mu, result);
+	return result;
+}
+
+
+/*
+ * 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;
+
+	i2400mu->tx_kthread = kthread_run(i2400mu_txd, i2400mu, "%s-tx",
+					  wimax_dev->name);
+	if (IS_ERR(i2400mu->tx_kthread)) {
+		result = PTR_ERR(i2400mu->tx_kthread);
+		dev_err(dev, "TX: cannot start thread: %d\n", result);
+	}
+	return result;
+}
+
+void i2400mu_tx_release(struct i2400mu *i2400mu)
+{
+	kthread_stop(i2400mu->tx_kthread);
+}