/*
* 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
* appropriate 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/slab.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.
* Will return NULL if it cannot reallocate -- this can be
* considered a transient retryable 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->endpoint_cfg.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, 200);
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 -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");
goto do_reset;
}
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:
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) {
kfree_skb(rx_skb);
rx_skb = NULL;
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_offset(new_skb));
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");
do_reset:
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;
unsigned long flags;
d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
spin_lock_irqsave(&i2400m->rx_lock, flags);
BUG_ON(i2400mu->rx_kthread != NULL);
i2400mu->rx_kthread = current;
spin_unlock_irqrestore(&i2400m->rx_lock, flags);
while (1) {
d_printf(2, dev, "RX: 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 == NULL || 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:
spin_lock_irqsave(&i2400m->rx_lock, flags);
i2400mu->rx_kthread = NULL;
spin_unlock_irqrestore(&i2400m->rx_lock, flags);
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;
struct task_struct *kthread;
kthread = kthread_run(i2400mu_rxd, i2400mu, "%s-rx",
wimax_dev->name);
/* the kthread function sets i2400mu->rx_thread */
if (IS_ERR(kthread)) {
result = PTR_ERR(kthread);
dev_err(dev, "RX: cannot start thread: %d\n", result);
}
return result;
}
void i2400mu_rx_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->rx_lock, flags);
kthread = i2400mu->rx_kthread;
i2400mu->rx_kthread = NULL;
spin_unlock_irqrestore(&i2400m->rx_lock, flags);
if (kthread)
kthread_stop(kthread);
else
d_printf(1, dev, "RX: kthread had already exited\n");
}
