1 /*
2 * Intel Wireless WiMAX Connection 2400m
3 * USB RX handling
4 *
5 *
6 * Copyright (C) 2007-2008 Intel Corporation. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * * Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * * Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in
16 * the documentation and/or other materials provided with the
17 * distribution.
18 * * Neither the name of Intel Corporation nor the names of its
19 * contributors may be used to endorse or promote products derived
20 * from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
25 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
26 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
27 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
28 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
32 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 *
34 *
35 * Intel Corporation <linux-wimax@intel.com>
36 * Yanir Lubetkin <yanirx.lubetkin@intel.com>
37 * - Initial implementation
38 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
39 * - Use skb_clone(), break up processing in chunks
40 * - Split transport/device specific
41 * - Make buffer size dynamic to exert less memory pressure
42 *
43 *
44 * This handles the RX path on USB.
45 *
46 * When a notification is received that says 'there is RX data ready',
47 * we call i2400mu_rx_kick(); that wakes up the RX kthread, which
48 * reads a buffer from USB and passes it to i2400m_rx() in the generic
49 * handling code. The RX buffer has an specific format that is
50 * described in rx.c.
51 *
52 * We use a kernel thread in a loop because:
53 *
54 * - we want to be able to call the USB power management get/put
55 * functions (blocking) before each transaction.
56 *
57 * - We might get a lot of notifications and we don't want to submit
58 * a zillion reads; by serializing, we are throttling.
59 *
60 * - RX data processing can get heavy enough so that it is not
61 * appropiate for doing it in the USB callback; thus we run it in a
62 * process context.
63 *
64 * We provide a read buffer of an arbitrary size (short of a page); if
65 * the callback reports -EOVERFLOW, it means it was too small, so we
66 * just double the size and retry (being careful to append, as
67 * sometimes the device provided some data). Every now and then we
68 * check if the average packet size is smaller than the current packet
69 * size and if so, we halve it. At the end, the size of the
70 * preallocated buffer should be following the average received
71 * transaction size, adapting dynamically to it.
72 *
73 * ROADMAP
74 *
75 * i2400mu_rx_kick() Called from notif.c when we get a
76 * 'data ready' notification
77 * i2400mu_rxd() Kernel RX daemon
78 * i2400mu_rx() Receive USB data
79 * i2400m_rx() Send data to generic i2400m RX handling
80 *
81 * i2400mu_rx_setup() called from i2400mu_bus_dev_start()
82 *
83 * i2400mu_rx_release() called from i2400mu_bus_dev_stop()
84 */
85 #include <linux/workqueue.h>
86 #include <linux/usb.h>
87 #include "i2400m-usb.h"
88
89
90 #define D_SUBMODULE rx
91 #include "usb-debug-levels.h"
92
93 /*
94 * Dynamic RX size
95 *
96 * We can't let the rx_size be a multiple of 512 bytes (the RX
97 * endpoint's max packet size). On some USB host controllers (we
98 * haven't been able to fully characterize which), if the device is
99 * about to send (for example) X bytes and we only post a buffer to
100 * receive n*512, it will fail to mark that as babble (so that
101 * i2400mu_rx() [case -EOVERFLOW] can resize the buffer and get the
102 * rest).
103 *
104 * So on growing or shrinking, if it is a multiple of the
105 * maxpacketsize, we remove some (instead of incresing some, so in a
106 * buddy allocator we try to waste less space).
107 *
108 * Note we also need a hook for this on i2400mu_rx() -- when we do the
109 * first read, we are sure we won't hit this spot because
110 * i240mm->rx_size has been set properly. However, if we have to
111 * double because of -EOVERFLOW, when we launch the read to get the
112 * rest of the data, we *have* to make sure that also is not a
113 * multiple of the max_pkt_size.
114 */
115
116 static
i2400mu_rx_size_grow(struct i2400mu * i2400mu)117 size_t i2400mu_rx_size_grow(struct i2400mu *i2400mu)
118 {
119 struct device *dev = &i2400mu->usb_iface->dev;
120 size_t rx_size;
121 const size_t max_pkt_size = 512;
122
123 rx_size = 2 * i2400mu->rx_size;
124 if (rx_size % max_pkt_size == 0) {
125 rx_size -= 8;
126 d_printf(1, dev,
127 "RX: expected size grew to %zu [adjusted -8] "
128 "from %zu\n",
129 rx_size, i2400mu->rx_size);
130 } else
131 d_printf(1, dev,
132 "RX: expected size grew to %zu from %zu\n",
133 rx_size, i2400mu->rx_size);
134 return rx_size;
135 }
136
137
138 static
i2400mu_rx_size_maybe_shrink(struct i2400mu * i2400mu)139 void i2400mu_rx_size_maybe_shrink(struct i2400mu *i2400mu)
140 {
141 const size_t max_pkt_size = 512;
142 struct device *dev = &i2400mu->usb_iface->dev;
143
144 if (unlikely(i2400mu->rx_size_cnt >= 100
145 && i2400mu->rx_size_auto_shrink)) {
146 size_t avg_rx_size =
147 i2400mu->rx_size_acc / i2400mu->rx_size_cnt;
148 size_t new_rx_size = i2400mu->rx_size / 2;
149 if (avg_rx_size < new_rx_size) {
150 if (new_rx_size % max_pkt_size == 0) {
151 new_rx_size -= 8;
152 d_printf(1, dev,
153 "RX: expected size shrank to %zu "
154 "[adjusted -8] from %zu\n",
155 new_rx_size, i2400mu->rx_size);
156 } else
157 d_printf(1, dev,
158 "RX: expected size shrank to %zu "
159 "from %zu\n",
160 new_rx_size, i2400mu->rx_size);
161 i2400mu->rx_size = new_rx_size;
162 i2400mu->rx_size_cnt = 0;
163 i2400mu->rx_size_acc = i2400mu->rx_size;
164 }
165 }
166 }
167
168 /*
169 * Receive a message with payloads from the USB bus into an skb
170 *
171 * @i2400mu: USB device descriptor
172 * @rx_skb: skb where to place the received message
173 *
174 * Deals with all the USB-specifics of receiving, dynamically
175 * increasing the buffer size if so needed. Returns the payload in the
176 * skb, ready to process. On a zero-length packet, we retry.
177 *
178 * On soft USB errors, we retry (until they become too frequent and
179 * then are promoted to hard); on hard USB errors, we reset the
180 * device. On other errors (skb realloacation, we just drop it and
181 * hope for the next invocation to solve it).
182 *
183 * Returns: pointer to the skb if ok, ERR_PTR on error.
184 * NOTE: this function might realloc the skb (if it is too small),
185 * so always update with the one returned.
186 * ERR_PTR() is < 0 on error.
187 * Will return NULL if it cannot reallocate -- this can be
188 * considered a transient retryable error.
189 */
190 static
i2400mu_rx(struct i2400mu * i2400mu,struct sk_buff * rx_skb)191 struct sk_buff *i2400mu_rx(struct i2400mu *i2400mu, struct sk_buff *rx_skb)
192 {
193 int result = 0;
194 struct device *dev = &i2400mu->usb_iface->dev;
195 int usb_pipe, read_size, rx_size, do_autopm;
196 struct usb_endpoint_descriptor *epd;
197 const size_t max_pkt_size = 512;
198
199 d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
200 do_autopm = atomic_read(&i2400mu->do_autopm);
201 result = do_autopm ?
202 usb_autopm_get_interface(i2400mu->usb_iface) : 0;
203 if (result < 0) {
204 dev_err(dev, "RX: can't get autopm: %d\n", result);
205 do_autopm = 0;
206 }
207 epd = usb_get_epd(i2400mu->usb_iface, I2400MU_EP_BULK_IN);
208 usb_pipe = usb_rcvbulkpipe(i2400mu->usb_dev, epd->bEndpointAddress);
209 retry:
210 rx_size = skb_end_pointer(rx_skb) - rx_skb->data - rx_skb->len;
211 if (unlikely(rx_size % max_pkt_size == 0)) {
212 rx_size -= 8;
213 d_printf(1, dev, "RX: rx_size adapted to %d [-8]\n", rx_size);
214 }
215 result = usb_bulk_msg(
216 i2400mu->usb_dev, usb_pipe, rx_skb->data + rx_skb->len,
217 rx_size, &read_size, HZ);
218 usb_mark_last_busy(i2400mu->usb_dev);
219 switch (result) {
220 case 0:
221 if (read_size == 0)
222 goto retry; /* ZLP, just resubmit */
223 skb_put(rx_skb, read_size);
224 break;
225 case -EINVAL: /* while removing driver */
226 case -ENODEV: /* dev disconnect ... */
227 case -ENOENT: /* just ignore it */
228 case -ESHUTDOWN:
229 case -ECONNRESET:
230 break;
231 case -EOVERFLOW: { /* too small, reallocate */
232 struct sk_buff *new_skb;
233 rx_size = i2400mu_rx_size_grow(i2400mu);
234 if (rx_size <= (1 << 16)) /* cap it */
235 i2400mu->rx_size = rx_size;
236 else if (printk_ratelimit()) {
237 dev_err(dev, "BUG? rx_size up to %d\n", rx_size);
238 result = -EINVAL;
239 goto out;
240 }
241 skb_put(rx_skb, read_size);
242 new_skb = skb_copy_expand(rx_skb, 0, rx_size - rx_skb->len,
243 GFP_KERNEL);
244 if (new_skb == NULL) {
245 if (printk_ratelimit())
246 dev_err(dev, "RX: Can't reallocate skb to %d; "
247 "RX dropped\n", rx_size);
248 kfree_skb(rx_skb);
249 rx_skb = NULL;
250 goto out; /* drop it...*/
251 }
252 kfree_skb(rx_skb);
253 rx_skb = new_skb;
254 i2400mu->rx_size_cnt = 0;
255 i2400mu->rx_size_acc = i2400mu->rx_size;
256 d_printf(1, dev, "RX: size changed to %d, received %d, "
257 "copied %d, capacity %ld\n",
258 rx_size, read_size, rx_skb->len,
259 (long) (skb_end_pointer(new_skb) - new_skb->head));
260 goto retry;
261 }
262 /* In most cases, it happens due to the hardware scheduling a
263 * read when there was no data - unfortunately, we have no way
264 * to tell this timeout from a USB timeout. So we just ignore
265 * it. */
266 case -ETIMEDOUT:
267 dev_err(dev, "RX: timeout: %d\n", result);
268 result = 0;
269 break;
270 default: /* Any error */
271 if (edc_inc(&i2400mu->urb_edc,
272 EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME))
273 goto error_reset;
274 dev_err(dev, "RX: error receiving URB: %d, retrying\n", result);
275 goto retry;
276 }
277 out:
278 if (do_autopm)
279 usb_autopm_put_interface(i2400mu->usb_iface);
280 d_fnend(4, dev, "(i2400mu %p) = %p\n", i2400mu, rx_skb);
281 return rx_skb;
282
283 error_reset:
284 dev_err(dev, "RX: maximum errors in URB exceeded; "
285 "resetting device\n");
286 usb_queue_reset_device(i2400mu->usb_iface);
287 rx_skb = ERR_PTR(result);
288 goto out;
289 }
290
291
292 /*
293 * Kernel thread for USB reception of data
294 *
295 * This thread waits for a kick; once kicked, it will allocate an skb
296 * and receive a single message to it from USB (using
297 * i2400mu_rx()). Once received, it is passed to the generic i2400m RX
298 * code for processing.
299 *
300 * When done processing, it runs some dirty statistics to verify if
301 * the last 100 messages received were smaller than half of the
302 * current RX buffer size. In that case, the RX buffer size is
303 * halved. This will helps lowering the pressure on the memory
304 * allocator.
305 *
306 * Hard errors force the thread to exit.
307 */
308 static
i2400mu_rxd(void * _i2400mu)309 int i2400mu_rxd(void *_i2400mu)
310 {
311 int result = 0;
312 struct i2400mu *i2400mu = _i2400mu;
313 struct i2400m *i2400m = &i2400mu->i2400m;
314 struct device *dev = &i2400mu->usb_iface->dev;
315 struct net_device *net_dev = i2400m->wimax_dev.net_dev;
316 size_t pending;
317 int rx_size;
318 struct sk_buff *rx_skb;
319
320 d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
321 while (1) {
322 d_printf(2, dev, "TX: waiting for messages\n");
323 pending = 0;
324 wait_event_interruptible(
325 i2400mu->rx_wq,
326 (kthread_should_stop() /* check this first! */
327 || (pending = atomic_read(&i2400mu->rx_pending_count)))
328 );
329 if (kthread_should_stop())
330 break;
331 if (pending == 0)
332 continue;
333 rx_size = i2400mu->rx_size;
334 d_printf(2, dev, "RX: reading up to %d bytes\n", rx_size);
335 rx_skb = __netdev_alloc_skb(net_dev, rx_size, GFP_KERNEL);
336 if (rx_skb == NULL) {
337 dev_err(dev, "RX: can't allocate skb [%d bytes]\n",
338 rx_size);
339 msleep(50); /* give it some time? */
340 continue;
341 }
342
343 /* Receive the message with the payloads */
344 rx_skb = i2400mu_rx(i2400mu, rx_skb);
345 result = PTR_ERR(rx_skb);
346 if (IS_ERR(rx_skb))
347 goto out;
348 atomic_dec(&i2400mu->rx_pending_count);
349 if (rx_skb == NULL || rx_skb->len == 0) {
350 /* some "ignorable" condition */
351 kfree_skb(rx_skb);
352 continue;
353 }
354
355 /* Deliver the message to the generic i2400m code */
356 i2400mu->rx_size_cnt++;
357 i2400mu->rx_size_acc += rx_skb->len;
358 result = i2400m_rx(i2400m, rx_skb);
359 if (result == -EIO
360 && edc_inc(&i2400mu->urb_edc,
361 EDC_MAX_ERRORS, EDC_ERROR_TIMEFRAME)) {
362 goto error_reset;
363 }
364
365 /* Maybe adjust RX buffer size */
366 i2400mu_rx_size_maybe_shrink(i2400mu);
367 }
368 result = 0;
369 out:
370 d_fnend(4, dev, "(i2400mu %p) = %d\n", i2400mu, result);
371 return result;
372
373 error_reset:
374 dev_err(dev, "RX: maximum errors in received buffer exceeded; "
375 "resetting device\n");
376 usb_queue_reset_device(i2400mu->usb_iface);
377 goto out;
378 }
379
380
381 /*
382 * Start reading from the device
383 *
384 * @i2400m: device instance
385 *
386 * Notify the RX thread that there is data pending.
387 */
i2400mu_rx_kick(struct i2400mu * i2400mu)388 void i2400mu_rx_kick(struct i2400mu *i2400mu)
389 {
390 struct i2400m *i2400m = &i2400mu->i2400m;
391 struct device *dev = &i2400mu->usb_iface->dev;
392
393 d_fnstart(3, dev, "(i2400mu %p)\n", i2400m);
394 atomic_inc(&i2400mu->rx_pending_count);
395 wake_up_all(&i2400mu->rx_wq);
396 d_fnend(3, dev, "(i2400m %p) = void\n", i2400m);
397 }
398
399
i2400mu_rx_setup(struct i2400mu * i2400mu)400 int i2400mu_rx_setup(struct i2400mu *i2400mu)
401 {
402 int result = 0;
403 struct i2400m *i2400m = &i2400mu->i2400m;
404 struct device *dev = &i2400mu->usb_iface->dev;
405 struct wimax_dev *wimax_dev = &i2400m->wimax_dev;
406
407 i2400mu->rx_kthread = kthread_run(i2400mu_rxd, i2400mu, "%s-rx",
408 wimax_dev->name);
409 if (IS_ERR(i2400mu->rx_kthread)) {
410 result = PTR_ERR(i2400mu->rx_kthread);
411 dev_err(dev, "RX: cannot start thread: %d\n", result);
412 }
413 return result;
414 }
415
i2400mu_rx_release(struct i2400mu * i2400mu)416 void i2400mu_rx_release(struct i2400mu *i2400mu)
417 {
418 kthread_stop(i2400mu->rx_kthread);
419 }
420
421