Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
/* $FreeBSD$ */
/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#ifdef USB_GLOBAL_INCLUDE_FILE
#include USB_GLOBAL_INCLUDE_FILE
#else
#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>
#include <dev/usb/usbdi_util.h>
#include <dev/usb/usb_process.h>

#define	USB_DEBUG_VAR usb_proc_debug
#include <dev/usb/usb_debug.h>
#include <dev/usb/usb_util.h>

#include <sys/proc.h>
#include <sys/kthread.h>
#include <sys/sched.h>
#endif			/* USB_GLOBAL_INCLUDE_FILE */

#if (__FreeBSD_version < 700000)
#define	thread_lock(td) mtx_lock_spin(&sched_lock)
#define	thread_unlock(td) mtx_unlock_spin(&sched_lock)
#endif

#if (__FreeBSD_version >= 800000)
static struct proc *usbproc;
static int usb_pcount;
#define	USB_THREAD_CREATE(f, s, p, ...) \
		kproc_kthread_add((f), (s), &usbproc, (p), RFHIGHPID, \
		    0, "usb", __VA_ARGS__)
#if (__FreeBSD_version >= 900000)
#define	USB_THREAD_SUSPEND_CHECK() kthread_suspend_check()
#else
#define	USB_THREAD_SUSPEND_CHECK() kthread_suspend_check(curthread)
#endif
#define	USB_THREAD_SUSPEND(p)   kthread_suspend(p,0)
#define	USB_THREAD_EXIT(err)	kthread_exit()
#else
#define	USB_THREAD_CREATE(f, s, p, ...) \
		kthread_create((f), (s), (p), RFHIGHPID, 0, __VA_ARGS__)
#define	USB_THREAD_SUSPEND_CHECK() kthread_suspend_check(curproc)
#define	USB_THREAD_SUSPEND(p)   kthread_suspend(p,0)
#define	USB_THREAD_EXIT(err)	kthread_exit(err)
#endif

#ifdef USB_DEBUG
static int usb_proc_debug;

static SYSCTL_NODE(_hw_usb, OID_AUTO, proc, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "USB process");
SYSCTL_INT(_hw_usb_proc, OID_AUTO, debug, CTLFLAG_RWTUN, &usb_proc_debug, 0,
    "Debug level");
#endif

/*------------------------------------------------------------------------*
 *	usb_process
 *
 * This function is the USB process dispatcher.
 *------------------------------------------------------------------------*/
static void
usb_process(void *arg)
{
	struct usb_process *up = arg;
	struct usb_proc_msg *pm;
	struct thread *td;

	/* in case of attach error, check for suspended */
	USB_THREAD_SUSPEND_CHECK();

	/* adjust priority */
	td = curthread;
	thread_lock(td);
	sched_prio(td, up->up_prio);
	thread_unlock(td);

	USB_MTX_LOCK(up->up_mtx);

	up->up_curtd = td;

	while (1) {
		if (up->up_gone)
			break;

		/*
		 * NOTE to reimplementors: dequeueing a command from the
		 * "used" queue and executing it must be atomic, with regard
		 * to the "up_mtx" mutex. That means any attempt to queue a
		 * command by another thread must be blocked until either:
		 *
		 * 1) the command sleeps
		 *
		 * 2) the command returns
		 *
		 * Here is a practical example that shows how this helps
		 * solving a problem:
		 *
		 * Assume that you want to set the baud rate on a USB serial
		 * device. During the programming of the device you don't
		 * want to receive nor transmit any data, because it will be
		 * garbage most likely anyway. The programming of our USB
		 * device takes 20 milliseconds and it needs to call
		 * functions that sleep.
		 *
		 * Non-working solution: Before we queue the programming
		 * command, we stop transmission and reception of data. Then
		 * we queue a programming command. At the end of the
		 * programming command we enable transmission and reception
		 * of data.
		 *
		 * Problem: If a second programming command is queued while the
		 * first one is sleeping, we end up enabling transmission
		 * and reception of data too early.
		 *
		 * Working solution: Before we queue the programming command,
		 * we stop transmission and reception of data. Then we queue
		 * a programming command. Then we queue a second command
		 * that only enables transmission and reception of data.
		 *
		 * Why it works: If a second programming command is queued
		 * while the first one is sleeping, then the queueing of a
		 * second command to enable the data transfers, will cause
		 * the previous one, which is still on the queue, to be
		 * removed from the queue, and re-inserted after the last
		 * baud rate programming command, which then gives the
		 * desired result.
		 */
		pm = TAILQ_FIRST(&up->up_qhead);

		if (pm) {
			DPRINTF("Message pm=%p, cb=%p (enter)\n",
			    pm, pm->pm_callback);

			(pm->pm_callback) (pm);

			if (pm == TAILQ_FIRST(&up->up_qhead)) {
				/* nothing changed */
				TAILQ_REMOVE(&up->up_qhead, pm, pm_qentry);
				pm->pm_qentry.tqe_prev = NULL;
			}
			DPRINTF("Message pm=%p (leave)\n", pm);

			continue;
		}
		/* end of messages - check if anyone is waiting for sync */
		if (up->up_dsleep) {
			up->up_dsleep = 0;
			cv_broadcast(&up->up_drain);
		}
		up->up_msleep = 1;
		cv_wait(&up->up_cv, up->up_mtx);
	}

	up->up_ptr = NULL;
	cv_signal(&up->up_cv);
	USB_MTX_UNLOCK(up->up_mtx);
#if (__FreeBSD_version >= 800000)
	/* Clear the proc pointer if this is the last thread. */
	if (--usb_pcount == 0)
		usbproc = NULL;
#endif

	USB_THREAD_EXIT(0);
}

/*------------------------------------------------------------------------*
 *	usb_proc_create
 *
 * This function will create a process using the given "prio" that can
 * execute callbacks. The mutex pointed to by "p_mtx" will be applied
 * before calling the callbacks and released after that the callback
 * has returned. The structure pointed to by "up" is assumed to be
 * zeroed before this function is called.
 *
 * Return values:
 *    0: success
 * Else: failure
 *------------------------------------------------------------------------*/
int
usb_proc_create(struct usb_process *up, struct mtx *p_mtx,
    const char *pmesg, uint8_t prio)
{
	up->up_mtx = p_mtx;
	up->up_prio = prio;

	TAILQ_INIT(&up->up_qhead);

	cv_init(&up->up_cv, "-");
	cv_init(&up->up_drain, "usbdrain");

	if (USB_THREAD_CREATE(&usb_process, up,
	    &up->up_ptr, "%s", pmesg)) {
		DPRINTFN(0, "Unable to create USB process.");
		up->up_ptr = NULL;
		goto error;
	}
#if (__FreeBSD_version >= 800000)
	usb_pcount++;
#endif
	return (0);

error:
	usb_proc_free(up);
	return (ENOMEM);
}

/*------------------------------------------------------------------------*
 *	usb_proc_free
 *
 * NOTE: If the structure pointed to by "up" is all zero, this
 * function does nothing.
 *
 * NOTE: Messages that are pending on the process queue will not be
 * removed nor called.
 *------------------------------------------------------------------------*/
void
usb_proc_free(struct usb_process *up)
{
	/* check if not initialised */
	if (up->up_mtx == NULL)
		return;

	usb_proc_drain(up);

	cv_destroy(&up->up_cv);
	cv_destroy(&up->up_drain);

	/* make sure that we do not enter here again */
	up->up_mtx = NULL;
}

/*------------------------------------------------------------------------*
 *	usb_proc_msignal
 *
 * This function will queue one of the passed USB process messages on
 * the USB process queue. The first message that is not already queued
 * will get queued. If both messages are already queued the one queued
 * last will be removed from the queue and queued in the end. The USB
 * process mutex must be locked when calling this function. This
 * function exploits the fact that a process can only do one callback
 * at a time. The message that was queued is returned.
 *------------------------------------------------------------------------*/
void   *
usb_proc_msignal(struct usb_process *up, void *_pm0, void *_pm1)
{
	struct usb_proc_msg *pm0 = _pm0;
	struct usb_proc_msg *pm1 = _pm1;
	struct usb_proc_msg *pm2;
	usb_size_t d;
	uint8_t t;

	/* check if gone or in polling mode, return dummy value */
	if (up->up_gone != 0 ||
	    USB_IN_POLLING_MODE_FUNC() != 0)
		return (_pm0);

	USB_MTX_ASSERT(up->up_mtx, MA_OWNED);

	t = 0;

	if (pm0->pm_qentry.tqe_prev) {
		t |= 1;
	}
	if (pm1->pm_qentry.tqe_prev) {
		t |= 2;
	}
	if (t == 0) {
		/*
		 * No entries are queued. Queue "pm0" and use the existing
		 * message number.
		 */
		pm2 = pm0;
	} else if (t == 1) {
		/* Check if we need to increment the message number. */
		if (pm0->pm_num == up->up_msg_num) {
			up->up_msg_num++;
		}
		pm2 = pm1;
	} else if (t == 2) {
		/* Check if we need to increment the message number. */
		if (pm1->pm_num == up->up_msg_num) {
			up->up_msg_num++;
		}
		pm2 = pm0;
	} else if (t == 3) {
		/*
		 * Both entries are queued. Re-queue the entry closest to
		 * the end.
		 */
		d = (pm1->pm_num - pm0->pm_num);

		/* Check sign after subtraction */
		if (d & 0x80000000) {
			pm2 = pm0;
		} else {
			pm2 = pm1;
		}

		TAILQ_REMOVE(&up->up_qhead, pm2, pm_qentry);
	} else {
		pm2 = NULL;		/* panic - should not happen */
	}

	DPRINTF(" t=%u, num=%u\n", t, up->up_msg_num);

	/* Put message last on queue */

	pm2->pm_num = up->up_msg_num;
	TAILQ_INSERT_TAIL(&up->up_qhead, pm2, pm_qentry);

	/* Check if we need to wakeup the USB process. */

	if (up->up_msleep) {
		up->up_msleep = 0;	/* save "cv_signal()" calls */
		cv_signal(&up->up_cv);
	}
	return (pm2);
}

/*------------------------------------------------------------------------*
 *	usb_proc_is_gone
 *
 * Return values:
 *    0: USB process is running
 * Else: USB process is tearing down
 *------------------------------------------------------------------------*/
uint8_t
usb_proc_is_gone(struct usb_process *up)
{
	if (up->up_gone)
		return (1);

	/*
	 * Allow calls when up_mtx is NULL, before the USB process
	 * structure is initialised.
	 */
	if (up->up_mtx != NULL)
		USB_MTX_ASSERT(up->up_mtx, MA_OWNED);
	return (0);
}

/*------------------------------------------------------------------------*
 *	usb_proc_mwait
 *
 * This function will return when the USB process message pointed to
 * by "pm" is no longer on a queue. This function must be called
 * having "up->up_mtx" locked.
 *------------------------------------------------------------------------*/
void
usb_proc_mwait(struct usb_process *up, void *_pm0, void *_pm1)
{
	struct usb_proc_msg *pm0 = _pm0;
	struct usb_proc_msg *pm1 = _pm1;

	/* check if gone */
	if (up->up_gone)
		return;

	USB_MTX_ASSERT(up->up_mtx, MA_OWNED);

	if (up->up_curtd == curthread) {
		/* Just remove the messages from the queue. */
		if (pm0->pm_qentry.tqe_prev) {
			TAILQ_REMOVE(&up->up_qhead, pm0, pm_qentry);
			pm0->pm_qentry.tqe_prev = NULL;
		}
		if (pm1->pm_qentry.tqe_prev) {
			TAILQ_REMOVE(&up->up_qhead, pm1, pm_qentry);
			pm1->pm_qentry.tqe_prev = NULL;
		}
	} else
		while (pm0->pm_qentry.tqe_prev ||
		    pm1->pm_qentry.tqe_prev) {
			/* check if config thread is gone */
			if (up->up_gone)
				break;
			up->up_dsleep = 1;
			cv_wait(&up->up_drain, up->up_mtx);
		}
}

/*------------------------------------------------------------------------*
 *	usb_proc_drain
 *
 * This function will tear down an USB process, waiting for the
 * currently executing command to return.
 *
 * NOTE: If the structure pointed to by "up" is all zero,
 * this function does nothing.
 *------------------------------------------------------------------------*/
void
usb_proc_drain(struct usb_process *up)
{
	/* check if not initialised */
	if (up->up_mtx == NULL)
		return;
	/* handle special case with Giant */
	if (up->up_mtx != &Giant)
		USB_MTX_ASSERT(up->up_mtx, MA_NOTOWNED);

	USB_MTX_LOCK(up->up_mtx);

	/* Set the gone flag */

	up->up_gone = 1;

	while (up->up_ptr) {
		/* Check if we need to wakeup the USB process */

		if (up->up_msleep || up->up_csleep) {
			up->up_msleep = 0;
			up->up_csleep = 0;
			cv_signal(&up->up_cv);
		}
#ifndef EARLY_AP_STARTUP
		/* Check if we are still cold booted */
		if (cold) {
			USB_THREAD_SUSPEND(up->up_ptr);
			printf("WARNING: A USB process has "
			    "been left suspended\n");
			break;
		}
#endif
		cv_wait(&up->up_cv, up->up_mtx);
	}
	/* Check if someone is waiting - should not happen */

	if (up->up_dsleep) {
		up->up_dsleep = 0;
		cv_broadcast(&up->up_drain);
		DPRINTF("WARNING: Someone is waiting "
		    "for USB process drain!\n");
	}
	USB_MTX_UNLOCK(up->up_mtx);
}

/*------------------------------------------------------------------------*
 *	usb_proc_rewakeup
 *
 * This function is called to re-wakeup the given USB
 * process. This usually happens after that the USB system has been in
 * polling mode, like during a panic. This function must be called
 * having "up->up_mtx" locked.
 *------------------------------------------------------------------------*/
void
usb_proc_rewakeup(struct usb_process *up)
{
	/* check if not initialised */
	if (up->up_mtx == NULL)
		return;
	/* check if gone */
	if (up->up_gone)
		return;

	USB_MTX_ASSERT(up->up_mtx, MA_OWNED);

	if (up->up_msleep == 0) {
		/* re-wakeup */
		cv_signal(&up->up_cv);
	}
}

/*------------------------------------------------------------------------*
 *	usb_proc_is_called_from
 *
 * This function will return non-zero if called from inside the USB
 * process passed as first argument. Else this function returns zero.
 *------------------------------------------------------------------------*/
int
usb_proc_is_called_from(struct usb_process *up)
{
	return (up->up_curtd == curthread);
}