1/* $FreeBSD: stable/11/sys/dev/usb/usb_process.c 311798 2017-01-09 17:12:15Z hselasky $ */
2/*-
3 * Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#ifdef USB_GLOBAL_INCLUDE_FILE
28#include USB_GLOBAL_INCLUDE_FILE
29#else
30#include <sys/stdint.h>
31#include <sys/stddef.h>
32#include <sys/param.h>
33#include <sys/queue.h>
34#include <sys/types.h>
35#include <sys/systm.h>
36#include <sys/kernel.h>
37#include <sys/bus.h>
38#include <sys/module.h>
39#include <sys/lock.h>
40#include <sys/mutex.h>
41#include <sys/condvar.h>
42#include <sys/sysctl.h>
43#include <sys/sx.h>
44#include <sys/unistd.h>
45#include <sys/callout.h>
46#include <sys/malloc.h>
47#include <sys/priv.h>
48
49#include <dev/usb/usb.h>
50#include <dev/usb/usbdi.h>
51#include <dev/usb/usbdi_util.h>
52#include <dev/usb/usb_process.h>
53
54#define	USB_DEBUG_VAR usb_proc_debug
55#include <dev/usb/usb_debug.h>
56#include <dev/usb/usb_util.h>
57
58#include <sys/proc.h>
59#include <sys/kthread.h>
60#include <sys/sched.h>
61#endif			/* USB_GLOBAL_INCLUDE_FILE */
62
63#if (__FreeBSD_version < 700000)
64#define	thread_lock(td) mtx_lock_spin(&sched_lock)
65#define	thread_unlock(td) mtx_unlock_spin(&sched_lock)
66#endif
67
68#if (__FreeBSD_version >= 800000)
69static struct proc *usbproc;
70static int usb_pcount;
71#define	USB_THREAD_CREATE(f, s, p, ...) \
72		kproc_kthread_add((f), (s), &usbproc, (p), RFHIGHPID, \
73		    0, "usb", __VA_ARGS__)
74#if (__FreeBSD_version >= 900000)
75#define	USB_THREAD_SUSPEND_CHECK() kthread_suspend_check()
76#else
77#define	USB_THREAD_SUSPEND_CHECK() kthread_suspend_check(curthread)
78#endif
79#define	USB_THREAD_SUSPEND(p)   kthread_suspend(p,0)
80#define	USB_THREAD_EXIT(err)	kthread_exit()
81#else
82#define	USB_THREAD_CREATE(f, s, p, ...) \
83		kthread_create((f), (s), (p), RFHIGHPID, 0, __VA_ARGS__)
84#define	USB_THREAD_SUSPEND_CHECK() kthread_suspend_check(curproc)
85#define	USB_THREAD_SUSPEND(p)   kthread_suspend(p,0)
86#define	USB_THREAD_EXIT(err)	kthread_exit(err)
87#endif
88
89#ifdef USB_DEBUG
90static int usb_proc_debug;
91
92static SYSCTL_NODE(_hw_usb, OID_AUTO, proc, CTLFLAG_RW, 0, "USB process");
93SYSCTL_INT(_hw_usb_proc, OID_AUTO, debug, CTLFLAG_RWTUN, &usb_proc_debug, 0,
94    "Debug level");
95#endif
96
97/*------------------------------------------------------------------------*
98 *	usb_process
99 *
100 * This function is the USB process dispatcher.
101 *------------------------------------------------------------------------*/
102static void
103usb_process(void *arg)
104{
105	struct usb_process *up = arg;
106	struct usb_proc_msg *pm;
107	struct thread *td;
108
109	/* in case of attach error, check for suspended */
110	USB_THREAD_SUSPEND_CHECK();
111
112	/* adjust priority */
113	td = curthread;
114	thread_lock(td);
115	sched_prio(td, up->up_prio);
116	thread_unlock(td);
117
118	mtx_lock(up->up_mtx);
119
120	up->up_curtd = td;
121
122	while (1) {
123
124		if (up->up_gone)
125			break;
126
127		/*
128		 * NOTE to reimplementors: dequeueing a command from the
129		 * "used" queue and executing it must be atomic, with regard
130		 * to the "up_mtx" mutex. That means any attempt to queue a
131		 * command by another thread must be blocked until either:
132		 *
133		 * 1) the command sleeps
134		 *
135		 * 2) the command returns
136		 *
137		 * Here is a practical example that shows how this helps
138		 * solving a problem:
139		 *
140		 * Assume that you want to set the baud rate on a USB serial
141		 * device. During the programming of the device you don't
142		 * want to receive nor transmit any data, because it will be
143		 * garbage most likely anyway. The programming of our USB
144		 * device takes 20 milliseconds and it needs to call
145		 * functions that sleep.
146		 *
147		 * Non-working solution: Before we queue the programming
148		 * command, we stop transmission and reception of data. Then
149		 * we queue a programming command. At the end of the
150		 * programming command we enable transmission and reception
151		 * of data.
152		 *
153		 * Problem: If a second programming command is queued while the
154		 * first one is sleeping, we end up enabling transmission
155		 * and reception of data too early.
156		 *
157		 * Working solution: Before we queue the programming command,
158		 * we stop transmission and reception of data. Then we queue
159		 * a programming command. Then we queue a second command
160		 * that only enables transmission and reception of data.
161		 *
162		 * Why it works: If a second programming command is queued
163		 * while the first one is sleeping, then the queueing of a
164		 * second command to enable the data transfers, will cause
165		 * the previous one, which is still on the queue, to be
166		 * removed from the queue, and re-inserted after the last
167		 * baud rate programming command, which then gives the
168		 * desired result.
169		 */
170		pm = TAILQ_FIRST(&up->up_qhead);
171
172		if (pm) {
173			DPRINTF("Message pm=%p, cb=%p (enter)\n",
174			    pm, pm->pm_callback);
175
176			(pm->pm_callback) (pm);
177
178			if (pm == TAILQ_FIRST(&up->up_qhead)) {
179				/* nothing changed */
180				TAILQ_REMOVE(&up->up_qhead, pm, pm_qentry);
181				pm->pm_qentry.tqe_prev = NULL;
182			}
183			DPRINTF("Message pm=%p (leave)\n", pm);
184
185			continue;
186		}
187		/* end if messages - check if anyone is waiting for sync */
188		if (up->up_dsleep) {
189			up->up_dsleep = 0;
190			cv_broadcast(&up->up_drain);
191		}
192		up->up_msleep = 1;
193		cv_wait(&up->up_cv, up->up_mtx);
194	}
195
196	up->up_ptr = NULL;
197	cv_signal(&up->up_cv);
198	mtx_unlock(up->up_mtx);
199#if (__FreeBSD_version >= 800000)
200	/* Clear the proc pointer if this is the last thread. */
201	if (--usb_pcount == 0)
202		usbproc = NULL;
203#endif
204
205	USB_THREAD_EXIT(0);
206}
207
208/*------------------------------------------------------------------------*
209 *	usb_proc_create
210 *
211 * This function will create a process using the given "prio" that can
212 * execute callbacks. The mutex pointed to by "p_mtx" will be applied
213 * before calling the callbacks and released after that the callback
214 * has returned. The structure pointed to by "up" is assumed to be
215 * zeroed before this function is called.
216 *
217 * Return values:
218 *    0: success
219 * Else: failure
220 *------------------------------------------------------------------------*/
221int
222usb_proc_create(struct usb_process *up, struct mtx *p_mtx,
223    const char *pmesg, uint8_t prio)
224{
225	up->up_mtx = p_mtx;
226	up->up_prio = prio;
227
228	TAILQ_INIT(&up->up_qhead);
229
230	cv_init(&up->up_cv, "-");
231	cv_init(&up->up_drain, "usbdrain");
232
233	if (USB_THREAD_CREATE(&usb_process, up,
234	    &up->up_ptr, "%s", pmesg)) {
235		DPRINTFN(0, "Unable to create USB process.");
236		up->up_ptr = NULL;
237		goto error;
238	}
239#if (__FreeBSD_version >= 800000)
240	usb_pcount++;
241#endif
242	return (0);
243
244error:
245	usb_proc_free(up);
246	return (ENOMEM);
247}
248
249/*------------------------------------------------------------------------*
250 *	usb_proc_free
251 *
252 * NOTE: If the structure pointed to by "up" is all zero, this
253 * function does nothing.
254 *
255 * NOTE: Messages that are pending on the process queue will not be
256 * removed nor called.
257 *------------------------------------------------------------------------*/
258void
259usb_proc_free(struct usb_process *up)
260{
261	/* check if not initialised */
262	if (up->up_mtx == NULL)
263		return;
264
265	usb_proc_drain(up);
266
267	cv_destroy(&up->up_cv);
268	cv_destroy(&up->up_drain);
269
270	/* make sure that we do not enter here again */
271	up->up_mtx = NULL;
272}
273
274/*------------------------------------------------------------------------*
275 *	usb_proc_msignal
276 *
277 * This function will queue one of the passed USB process messages on
278 * the USB process queue. The first message that is not already queued
279 * will get queued. If both messages are already queued the one queued
280 * last will be removed from the queue and queued in the end. The USB
281 * process mutex must be locked when calling this function. This
282 * function exploits the fact that a process can only do one callback
283 * at a time. The message that was queued is returned.
284 *------------------------------------------------------------------------*/
285void   *
286usb_proc_msignal(struct usb_process *up, void *_pm0, void *_pm1)
287{
288	struct usb_proc_msg *pm0 = _pm0;
289	struct usb_proc_msg *pm1 = _pm1;
290	struct usb_proc_msg *pm2;
291	usb_size_t d;
292	uint8_t t;
293
294	/* check if gone, return dummy value */
295	if (up->up_gone)
296		return (_pm0);
297
298	mtx_assert(up->up_mtx, MA_OWNED);
299
300	t = 0;
301
302	if (pm0->pm_qentry.tqe_prev) {
303		t |= 1;
304	}
305	if (pm1->pm_qentry.tqe_prev) {
306		t |= 2;
307	}
308	if (t == 0) {
309		/*
310		 * No entries are queued. Queue "pm0" and use the existing
311		 * message number.
312		 */
313		pm2 = pm0;
314	} else if (t == 1) {
315		/* Check if we need to increment the message number. */
316		if (pm0->pm_num == up->up_msg_num) {
317			up->up_msg_num++;
318		}
319		pm2 = pm1;
320	} else if (t == 2) {
321		/* Check if we need to increment the message number. */
322		if (pm1->pm_num == up->up_msg_num) {
323			up->up_msg_num++;
324		}
325		pm2 = pm0;
326	} else if (t == 3) {
327		/*
328		 * Both entries are queued. Re-queue the entry closest to
329		 * the end.
330		 */
331		d = (pm1->pm_num - pm0->pm_num);
332
333		/* Check sign after subtraction */
334		if (d & 0x80000000) {
335			pm2 = pm0;
336		} else {
337			pm2 = pm1;
338		}
339
340		TAILQ_REMOVE(&up->up_qhead, pm2, pm_qentry);
341	} else {
342		pm2 = NULL;		/* panic - should not happen */
343	}
344
345	DPRINTF(" t=%u, num=%u\n", t, up->up_msg_num);
346
347	/* Put message last on queue */
348
349	pm2->pm_num = up->up_msg_num;
350	TAILQ_INSERT_TAIL(&up->up_qhead, pm2, pm_qentry);
351
352	/* Check if we need to wakeup the USB process. */
353
354	if (up->up_msleep) {
355		up->up_msleep = 0;	/* save "cv_signal()" calls */
356		cv_signal(&up->up_cv);
357	}
358	return (pm2);
359}
360
361/*------------------------------------------------------------------------*
362 *	usb_proc_is_gone
363 *
364 * Return values:
365 *    0: USB process is running
366 * Else: USB process is tearing down
367 *------------------------------------------------------------------------*/
368uint8_t
369usb_proc_is_gone(struct usb_process *up)
370{
371	if (up->up_gone)
372		return (1);
373
374	/*
375	 * Allow calls when up_mtx is NULL, before the USB process
376	 * structure is initialised.
377	 */
378	if (up->up_mtx != NULL)
379		mtx_assert(up->up_mtx, MA_OWNED);
380	return (0);
381}
382
383/*------------------------------------------------------------------------*
384 *	usb_proc_mwait
385 *
386 * This function will return when the USB process message pointed to
387 * by "pm" is no longer on a queue. This function must be called
388 * having "up->up_mtx" locked.
389 *------------------------------------------------------------------------*/
390void
391usb_proc_mwait(struct usb_process *up, void *_pm0, void *_pm1)
392{
393	struct usb_proc_msg *pm0 = _pm0;
394	struct usb_proc_msg *pm1 = _pm1;
395
396	/* check if gone */
397	if (up->up_gone)
398		return;
399
400	mtx_assert(up->up_mtx, MA_OWNED);
401
402	if (up->up_curtd == curthread) {
403		/* Just remove the messages from the queue. */
404		if (pm0->pm_qentry.tqe_prev) {
405			TAILQ_REMOVE(&up->up_qhead, pm0, pm_qentry);
406			pm0->pm_qentry.tqe_prev = NULL;
407		}
408		if (pm1->pm_qentry.tqe_prev) {
409			TAILQ_REMOVE(&up->up_qhead, pm1, pm_qentry);
410			pm1->pm_qentry.tqe_prev = NULL;
411		}
412	} else
413		while (pm0->pm_qentry.tqe_prev ||
414		    pm1->pm_qentry.tqe_prev) {
415			/* check if config thread is gone */
416			if (up->up_gone)
417				break;
418			up->up_dsleep = 1;
419			cv_wait(&up->up_drain, up->up_mtx);
420		}
421}
422
423/*------------------------------------------------------------------------*
424 *	usb_proc_drain
425 *
426 * This function will tear down an USB process, waiting for the
427 * currently executing command to return.
428 *
429 * NOTE: If the structure pointed to by "up" is all zero,
430 * this function does nothing.
431 *------------------------------------------------------------------------*/
432void
433usb_proc_drain(struct usb_process *up)
434{
435	/* check if not initialised */
436	if (up->up_mtx == NULL)
437		return;
438	/* handle special case with Giant */
439	if (up->up_mtx != &Giant)
440		mtx_assert(up->up_mtx, MA_NOTOWNED);
441
442	mtx_lock(up->up_mtx);
443
444	/* Set the gone flag */
445
446	up->up_gone = 1;
447
448	while (up->up_ptr) {
449
450		/* Check if we need to wakeup the USB process */
451
452		if (up->up_msleep || up->up_csleep) {
453			up->up_msleep = 0;
454			up->up_csleep = 0;
455			cv_signal(&up->up_cv);
456		}
457#ifndef EARLY_AP_STARTUP
458		/* Check if we are still cold booted */
459		if (cold) {
460			USB_THREAD_SUSPEND(up->up_ptr);
461			printf("WARNING: A USB process has "
462			    "been left suspended\n");
463			break;
464		}
465#endif
466		cv_wait(&up->up_cv, up->up_mtx);
467	}
468	/* Check if someone is waiting - should not happen */
469
470	if (up->up_dsleep) {
471		up->up_dsleep = 0;
472		cv_broadcast(&up->up_drain);
473		DPRINTF("WARNING: Someone is waiting "
474		    "for USB process drain!\n");
475	}
476	mtx_unlock(up->up_mtx);
477}
478
479/*------------------------------------------------------------------------*
480 *	usb_proc_rewakeup
481 *
482 * This function is called to re-wakeup the given USB
483 * process. This usually happens after that the USB system has been in
484 * polling mode, like during a panic. This function must be called
485 * having "up->up_mtx" locked.
486 *------------------------------------------------------------------------*/
487void
488usb_proc_rewakeup(struct usb_process *up)
489{
490	/* check if not initialised */
491	if (up->up_mtx == NULL)
492		return;
493	/* check if gone */
494	if (up->up_gone)
495		return;
496
497	mtx_assert(up->up_mtx, MA_OWNED);
498
499	if (up->up_msleep == 0) {
500		/* re-wakeup */
501		cv_signal(&up->up_cv);
502	}
503}
504
505/*------------------------------------------------------------------------*
506 *	usb_proc_is_called_from
507 *
508 * This function will return non-zero if called from inside the USB
509 * process passed as first argument. Else this function returns zero.
510 *------------------------------------------------------------------------*/
511int
512usb_proc_is_called_from(struct usb_process *up)
513{
514	return (up->up_curtd == curthread);
515}
516