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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Multiplexer subsystem
4 *
5 * Copyright (C) 2017 Axentia Technologies AB
6 *
7 * Author: Peter Rosin <peda@axentia.se>
8 */
9
10#define pr_fmt(fmt) "mux-core: " fmt
11
12#include <linux/delay.h>
13#include <linux/device.h>
14#include <linux/err.h>
15#include <linux/export.h>
16#include <linux/idr.h>
17#include <linux/init.h>
18#include <linux/module.h>
19#include <linux/mux/consumer.h>
20#include <linux/mux/driver.h>
21#include <linux/of.h>
22#include <linux/slab.h>
23
24/*
25 * The idle-as-is "state" is not an actual state that may be selected, it
26 * only implies that the state should not be changed. So, use that state
27 * as indication that the cached state of the multiplexer is unknown.
28 */
29#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
30
31/**
32 * struct mux_state - Represents a mux controller state specific to a given
33 * consumer.
34 * @mux: Pointer to a mux controller.
35 * @state: State of the mux to be selected.
36 *
37 * This structure is specific to the consumer that acquires it and has
38 * information specific to that consumer.
39 */
40struct mux_state {
41 struct mux_control *mux;
42 unsigned int state;
43};
44
45static struct class mux_class = {
46 .name = "mux",
47};
48
49static DEFINE_IDA(mux_ida);
50
51static int __init mux_init(void)
52{
53 ida_init(&mux_ida);
54 return class_register(&mux_class);
55}
56
57static void __exit mux_exit(void)
58{
59 class_unregister(&mux_class);
60 ida_destroy(&mux_ida);
61}
62
63static void mux_chip_release(struct device *dev)
64{
65 struct mux_chip *mux_chip = to_mux_chip(dev);
66
67 ida_simple_remove(&mux_ida, mux_chip->id);
68 kfree(mux_chip);
69}
70
71static const struct device_type mux_type = {
72 .name = "mux-chip",
73 .release = mux_chip_release,
74};
75
76/**
77 * mux_chip_alloc() - Allocate a mux-chip.
78 * @dev: The parent device implementing the mux interface.
79 * @controllers: The number of mux controllers to allocate for this chip.
80 * @sizeof_priv: Size of extra memory area for private use by the caller.
81 *
82 * After allocating the mux-chip with the desired number of mux controllers
83 * but before registering the chip, the mux driver is required to configure
84 * the number of valid mux states in the mux_chip->mux[N].states members and
85 * the desired idle state in the returned mux_chip->mux[N].idle_state members.
86 * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to
87 * provide a pointer to the operations struct in the mux_chip->ops member
88 * before registering the mux-chip with mux_chip_register.
89 *
90 * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
91 */
92struct mux_chip *mux_chip_alloc(struct device *dev,
93 unsigned int controllers, size_t sizeof_priv)
94{
95 struct mux_chip *mux_chip;
96 int i;
97
98 if (WARN_ON(!dev || !controllers))
99 return ERR_PTR(-EINVAL);
100
101 mux_chip = kzalloc(sizeof(*mux_chip) +
102 controllers * sizeof(*mux_chip->mux) +
103 sizeof_priv, GFP_KERNEL);
104 if (!mux_chip)
105 return ERR_PTR(-ENOMEM);
106
107 mux_chip->mux = (struct mux_control *)(mux_chip + 1);
108 mux_chip->dev.class = &mux_class;
109 mux_chip->dev.type = &mux_type;
110 mux_chip->dev.parent = dev;
111 mux_chip->dev.of_node = dev->of_node;
112 dev_set_drvdata(&mux_chip->dev, mux_chip);
113
114 mux_chip->id = ida_simple_get(&mux_ida, 0, 0, GFP_KERNEL);
115 if (mux_chip->id < 0) {
116 int err = mux_chip->id;
117
118 pr_err("muxchipX failed to get a device id\n");
119 kfree(mux_chip);
120 return ERR_PTR(err);
121 }
122 dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id);
123
124 mux_chip->controllers = controllers;
125 for (i = 0; i < controllers; ++i) {
126 struct mux_control *mux = &mux_chip->mux[i];
127
128 mux->chip = mux_chip;
129 sema_init(&mux->lock, 1);
130 mux->cached_state = MUX_CACHE_UNKNOWN;
131 mux->idle_state = MUX_IDLE_AS_IS;
132 mux->last_change = ktime_get();
133 }
134
135 device_initialize(&mux_chip->dev);
136
137 return mux_chip;
138}
139EXPORT_SYMBOL_GPL(mux_chip_alloc);
140
141static int mux_control_set(struct mux_control *mux, int state)
142{
143 int ret = mux->chip->ops->set(mux, state);
144
145 mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
146 if (ret >= 0)
147 mux->last_change = ktime_get();
148
149 return ret;
150}
151
152/**
153 * mux_chip_register() - Register a mux-chip, thus readying the controllers
154 * for use.
155 * @mux_chip: The mux-chip to register.
156 *
157 * Do not retry registration of the same mux-chip on failure. You should
158 * instead put it away with mux_chip_free() and allocate a new one, if you
159 * for some reason would like to retry registration.
160 *
161 * Return: Zero on success or a negative errno on error.
162 */
163int mux_chip_register(struct mux_chip *mux_chip)
164{
165 int i;
166 int ret;
167
168 for (i = 0; i < mux_chip->controllers; ++i) {
169 struct mux_control *mux = &mux_chip->mux[i];
170
171 if (mux->idle_state == mux->cached_state)
172 continue;
173
174 ret = mux_control_set(mux, mux->idle_state);
175 if (ret < 0) {
176 dev_err(&mux_chip->dev, "unable to set idle state\n");
177 return ret;
178 }
179 }
180
181 ret = device_add(&mux_chip->dev);
182 if (ret < 0)
183 dev_err(&mux_chip->dev,
184 "device_add failed in %s: %d\n", __func__, ret);
185 return ret;
186}
187EXPORT_SYMBOL_GPL(mux_chip_register);
188
189/**
190 * mux_chip_unregister() - Take the mux-chip off-line.
191 * @mux_chip: The mux-chip to unregister.
192 *
193 * mux_chip_unregister() reverses the effects of mux_chip_register().
194 * But not completely, you should not try to call mux_chip_register()
195 * on a mux-chip that has been registered before.
196 */
197void mux_chip_unregister(struct mux_chip *mux_chip)
198{
199 device_del(&mux_chip->dev);
200}
201EXPORT_SYMBOL_GPL(mux_chip_unregister);
202
203/**
204 * mux_chip_free() - Free the mux-chip for good.
205 * @mux_chip: The mux-chip to free.
206 *
207 * mux_chip_free() reverses the effects of mux_chip_alloc().
208 */
209void mux_chip_free(struct mux_chip *mux_chip)
210{
211 if (!mux_chip)
212 return;
213
214 put_device(&mux_chip->dev);
215}
216EXPORT_SYMBOL_GPL(mux_chip_free);
217
218static void devm_mux_chip_release(struct device *dev, void *res)
219{
220 struct mux_chip *mux_chip = *(struct mux_chip **)res;
221
222 mux_chip_free(mux_chip);
223}
224
225/**
226 * devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc().
227 * @dev: The parent device implementing the mux interface.
228 * @controllers: The number of mux controllers to allocate for this chip.
229 * @sizeof_priv: Size of extra memory area for private use by the caller.
230 *
231 * See mux_chip_alloc() for more details.
232 *
233 * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
234 */
235struct mux_chip *devm_mux_chip_alloc(struct device *dev,
236 unsigned int controllers,
237 size_t sizeof_priv)
238{
239 struct mux_chip **ptr, *mux_chip;
240
241 ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL);
242 if (!ptr)
243 return ERR_PTR(-ENOMEM);
244
245 mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv);
246 if (IS_ERR(mux_chip)) {
247 devres_free(ptr);
248 return mux_chip;
249 }
250
251 *ptr = mux_chip;
252 devres_add(dev, ptr);
253
254 return mux_chip;
255}
256EXPORT_SYMBOL_GPL(devm_mux_chip_alloc);
257
258static void devm_mux_chip_reg_release(struct device *dev, void *res)
259{
260 struct mux_chip *mux_chip = *(struct mux_chip **)res;
261
262 mux_chip_unregister(mux_chip);
263}
264
265/**
266 * devm_mux_chip_register() - Resource-managed version mux_chip_register().
267 * @dev: The parent device implementing the mux interface.
268 * @mux_chip: The mux-chip to register.
269 *
270 * See mux_chip_register() for more details.
271 *
272 * Return: Zero on success or a negative errno on error.
273 */
274int devm_mux_chip_register(struct device *dev,
275 struct mux_chip *mux_chip)
276{
277 struct mux_chip **ptr;
278 int res;
279
280 ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL);
281 if (!ptr)
282 return -ENOMEM;
283
284 res = mux_chip_register(mux_chip);
285 if (res) {
286 devres_free(ptr);
287 return res;
288 }
289
290 *ptr = mux_chip;
291 devres_add(dev, ptr);
292
293 return res;
294}
295EXPORT_SYMBOL_GPL(devm_mux_chip_register);
296
297/**
298 * mux_control_states() - Query the number of multiplexer states.
299 * @mux: The mux-control to query.
300 *
301 * Return: The number of multiplexer states.
302 */
303unsigned int mux_control_states(struct mux_control *mux)
304{
305 return mux->states;
306}
307EXPORT_SYMBOL_GPL(mux_control_states);
308
309/*
310 * The mux->lock must be down when calling this function.
311 */
312static int __mux_control_select(struct mux_control *mux, int state)
313{
314 int ret;
315
316 if (WARN_ON(state < 0 || state >= mux->states))
317 return -EINVAL;
318
319 if (mux->cached_state == state)
320 return 0;
321
322 ret = mux_control_set(mux, state);
323 if (ret >= 0)
324 return 0;
325
326 /* The mux update failed, try to revert if appropriate... */
327 if (mux->idle_state != MUX_IDLE_AS_IS)
328 mux_control_set(mux, mux->idle_state);
329
330 return ret;
331}
332
333static void mux_control_delay(struct mux_control *mux, unsigned int delay_us)
334{
335 ktime_t delayend;
336 s64 remaining;
337
338 if (!delay_us)
339 return;
340
341 delayend = ktime_add_us(mux->last_change, delay_us);
342 remaining = ktime_us_delta(delayend, ktime_get());
343 if (remaining > 0)
344 fsleep(remaining);
345}
346
347/**
348 * mux_control_select_delay() - Select the given multiplexer state.
349 * @mux: The mux-control to request a change of state from.
350 * @state: The new requested state.
351 * @delay_us: The time to delay (in microseconds) if the mux state is changed.
352 *
353 * On successfully selecting the mux-control state, it will be locked until
354 * there is a call to mux_control_deselect(). If the mux-control is already
355 * selected when mux_control_select() is called, the caller will be blocked
356 * until mux_control_deselect() or mux_state_deselect() is called (by someone
357 * else).
358 *
359 * Therefore, make sure to call mux_control_deselect() when the operation is
360 * complete and the mux-control is free for others to use, but do not call
361 * mux_control_deselect() if mux_control_select() fails.
362 *
363 * Return: 0 when the mux-control state has the requested state or a negative
364 * errno on error.
365 */
366int mux_control_select_delay(struct mux_control *mux, unsigned int state,
367 unsigned int delay_us)
368{
369 int ret;
370
371 ret = down_killable(&mux->lock);
372 if (ret < 0)
373 return ret;
374
375 ret = __mux_control_select(mux, state);
376 if (ret >= 0)
377 mux_control_delay(mux, delay_us);
378
379 if (ret < 0)
380 up(&mux->lock);
381
382 return ret;
383}
384EXPORT_SYMBOL_GPL(mux_control_select_delay);
385
386/**
387 * mux_state_select_delay() - Select the given multiplexer state.
388 * @mstate: The mux-state to select.
389 * @delay_us: The time to delay (in microseconds) if the mux state is changed.
390 *
391 * On successfully selecting the mux-state, its mux-control will be locked
392 * until there is a call to mux_state_deselect(). If the mux-control is already
393 * selected when mux_state_select() is called, the caller will be blocked
394 * until mux_state_deselect() or mux_control_deselect() is called (by someone
395 * else).
396 *
397 * Therefore, make sure to call mux_state_deselect() when the operation is
398 * complete and the mux-control is free for others to use, but do not call
399 * mux_state_deselect() if mux_state_select() fails.
400 *
401 * Return: 0 when the mux-state has been selected or a negative
402 * errno on error.
403 */
404int mux_state_select_delay(struct mux_state *mstate, unsigned int delay_us)
405{
406 return mux_control_select_delay(mstate->mux, mstate->state, delay_us);
407}
408EXPORT_SYMBOL_GPL(mux_state_select_delay);
409
410/**
411 * mux_control_try_select_delay() - Try to select the given multiplexer state.
412 * @mux: The mux-control to request a change of state from.
413 * @state: The new requested state.
414 * @delay_us: The time to delay (in microseconds) if the mux state is changed.
415 *
416 * On successfully selecting the mux-control state, it will be locked until
417 * mux_control_deselect() is called.
418 *
419 * Therefore, make sure to call mux_control_deselect() when the operation is
420 * complete and the mux-control is free for others to use, but do not call
421 * mux_control_deselect() if mux_control_try_select() fails.
422 *
423 * Return: 0 when the mux-control state has the requested state or a negative
424 * errno on error. Specifically -EBUSY if the mux-control is contended.
425 */
426int mux_control_try_select_delay(struct mux_control *mux, unsigned int state,
427 unsigned int delay_us)
428{
429 int ret;
430
431 if (down_trylock(&mux->lock))
432 return -EBUSY;
433
434 ret = __mux_control_select(mux, state);
435 if (ret >= 0)
436 mux_control_delay(mux, delay_us);
437
438 if (ret < 0)
439 up(&mux->lock);
440
441 return ret;
442}
443EXPORT_SYMBOL_GPL(mux_control_try_select_delay);
444
445/**
446 * mux_state_try_select_delay() - Try to select the given multiplexer state.
447 * @mstate: The mux-state to select.
448 * @delay_us: The time to delay (in microseconds) if the mux state is changed.
449 *
450 * On successfully selecting the mux-state, its mux-control will be locked
451 * until mux_state_deselect() is called.
452 *
453 * Therefore, make sure to call mux_state_deselect() when the operation is
454 * complete and the mux-control is free for others to use, but do not call
455 * mux_state_deselect() if mux_state_try_select() fails.
456 *
457 * Return: 0 when the mux-state has been selected or a negative errno on
458 * error. Specifically -EBUSY if the mux-control is contended.
459 */
460int mux_state_try_select_delay(struct mux_state *mstate, unsigned int delay_us)
461{
462 return mux_control_try_select_delay(mstate->mux, mstate->state, delay_us);
463}
464EXPORT_SYMBOL_GPL(mux_state_try_select_delay);
465
466/**
467 * mux_control_deselect() - Deselect the previously selected multiplexer state.
468 * @mux: The mux-control to deselect.
469 *
470 * It is required that a single call is made to mux_control_deselect() for
471 * each and every successful call made to either of mux_control_select() or
472 * mux_control_try_select().
473 *
474 * Return: 0 on success and a negative errno on error. An error can only
475 * occur if the mux has an idle state. Note that even if an error occurs, the
476 * mux-control is unlocked and is thus free for the next access.
477 */
478int mux_control_deselect(struct mux_control *mux)
479{
480 int ret = 0;
481
482 if (mux->idle_state != MUX_IDLE_AS_IS &&
483 mux->idle_state != mux->cached_state)
484 ret = mux_control_set(mux, mux->idle_state);
485
486 up(&mux->lock);
487
488 return ret;
489}
490EXPORT_SYMBOL_GPL(mux_control_deselect);
491
492/**
493 * mux_state_deselect() - Deselect the previously selected multiplexer state.
494 * @mstate: The mux-state to deselect.
495 *
496 * It is required that a single call is made to mux_state_deselect() for
497 * each and every successful call made to either of mux_state_select() or
498 * mux_state_try_select().
499 *
500 * Return: 0 on success and a negative errno on error. An error can only
501 * occur if the mux has an idle state. Note that even if an error occurs, the
502 * mux-control is unlocked and is thus free for the next access.
503 */
504int mux_state_deselect(struct mux_state *mstate)
505{
506 return mux_control_deselect(mstate->mux);
507}
508EXPORT_SYMBOL_GPL(mux_state_deselect);
509
510/* Note this function returns a reference to the mux_chip dev. */
511static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
512{
513 struct device *dev;
514
515 dev = class_find_device_by_of_node(&mux_class, np);
516
517 return dev ? to_mux_chip(dev) : NULL;
518}
519
520/*
521 * mux_get() - Get the mux-control for a device.
522 * @dev: The device that needs a mux-control.
523 * @mux_name: The name identifying the mux-control.
524 * @state: Pointer to where the requested state is returned, or NULL when
525 * the required multiplexer states are handled by other means.
526 *
527 * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
528 */
529static struct mux_control *mux_get(struct device *dev, const char *mux_name,
530 unsigned int *state)
531{
532 struct device_node *np = dev->of_node;
533 struct of_phandle_args args;
534 struct mux_chip *mux_chip;
535 unsigned int controller;
536 int index = 0;
537 int ret;
538
539 if (mux_name) {
540 if (state)
541 index = of_property_match_string(np, "mux-state-names",
542 mux_name);
543 else
544 index = of_property_match_string(np, "mux-control-names",
545 mux_name);
546 if (index < 0) {
547 dev_err(dev, "mux controller '%s' not found\n",
548 mux_name);
549 return ERR_PTR(index);
550 }
551 }
552
553 if (state)
554 ret = of_parse_phandle_with_args(np,
555 "mux-states", "#mux-state-cells",
556 index, &args);
557 else
558 ret = of_parse_phandle_with_args(np,
559 "mux-controls", "#mux-control-cells",
560 index, &args);
561 if (ret) {
562 dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
563 np, state ? "state" : "control", mux_name ?: "", index);
564 return ERR_PTR(ret);
565 }
566
567 mux_chip = of_find_mux_chip_by_node(args.np);
568 of_node_put(args.np);
569 if (!mux_chip)
570 return ERR_PTR(-EPROBE_DEFER);
571
572 controller = 0;
573 if (state) {
574 if (args.args_count > 2 || args.args_count == 0 ||
575 (args.args_count < 2 && mux_chip->controllers > 1)) {
576 dev_err(dev, "%pOF: wrong #mux-state-cells for %pOF\n",
577 np, args.np);
578 put_device(&mux_chip->dev);
579 return ERR_PTR(-EINVAL);
580 }
581
582 if (args.args_count == 2) {
583 controller = args.args[0];
584 *state = args.args[1];
585 } else {
586 *state = args.args[0];
587 }
588
589 } else {
590 if (args.args_count > 1 ||
591 (!args.args_count && mux_chip->controllers > 1)) {
592 dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n",
593 np, args.np);
594 put_device(&mux_chip->dev);
595 return ERR_PTR(-EINVAL);
596 }
597
598 if (args.args_count)
599 controller = args.args[0];
600 }
601
602 if (controller >= mux_chip->controllers) {
603 dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n",
604 np, controller, args.np);
605 put_device(&mux_chip->dev);
606 return ERR_PTR(-EINVAL);
607 }
608
609 return &mux_chip->mux[controller];
610}
611
612/**
613 * mux_control_get() - Get the mux-control for a device.
614 * @dev: The device that needs a mux-control.
615 * @mux_name: The name identifying the mux-control.
616 *
617 * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
618 */
619struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
620{
621 return mux_get(dev, mux_name, NULL);
622}
623EXPORT_SYMBOL_GPL(mux_control_get);
624
625/**
626 * mux_control_put() - Put away the mux-control for good.
627 * @mux: The mux-control to put away.
628 *
629 * mux_control_put() reverses the effects of mux_control_get().
630 */
631void mux_control_put(struct mux_control *mux)
632{
633 put_device(&mux->chip->dev);
634}
635EXPORT_SYMBOL_GPL(mux_control_put);
636
637static void devm_mux_control_release(struct device *dev, void *res)
638{
639 struct mux_control *mux = *(struct mux_control **)res;
640
641 mux_control_put(mux);
642}
643
644/**
645 * devm_mux_control_get() - Get the mux-control for a device, with resource
646 * management.
647 * @dev: The device that needs a mux-control.
648 * @mux_name: The name identifying the mux-control.
649 *
650 * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
651 */
652struct mux_control *devm_mux_control_get(struct device *dev,
653 const char *mux_name)
654{
655 struct mux_control **ptr, *mux;
656
657 ptr = devres_alloc(devm_mux_control_release, sizeof(*ptr), GFP_KERNEL);
658 if (!ptr)
659 return ERR_PTR(-ENOMEM);
660
661 mux = mux_control_get(dev, mux_name);
662 if (IS_ERR(mux)) {
663 devres_free(ptr);
664 return mux;
665 }
666
667 *ptr = mux;
668 devres_add(dev, ptr);
669
670 return mux;
671}
672EXPORT_SYMBOL_GPL(devm_mux_control_get);
673
674/*
675 * mux_state_get() - Get the mux-state for a device.
676 * @dev: The device that needs a mux-state.
677 * @mux_name: The name identifying the mux-state.
678 *
679 * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
680 */
681static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
682{
683 struct mux_state *mstate;
684
685 mstate = kzalloc(sizeof(*mstate), GFP_KERNEL);
686 if (!mstate)
687 return ERR_PTR(-ENOMEM);
688
689 mstate->mux = mux_get(dev, mux_name, &mstate->state);
690 if (IS_ERR(mstate->mux)) {
691 int err = PTR_ERR(mstate->mux);
692
693 kfree(mstate);
694 return ERR_PTR(err);
695 }
696
697 return mstate;
698}
699
700/*
701 * mux_state_put() - Put away the mux-state for good.
702 * @mstate: The mux-state to put away.
703 *
704 * mux_state_put() reverses the effects of mux_state_get().
705 */
706static void mux_state_put(struct mux_state *mstate)
707{
708 mux_control_put(mstate->mux);
709 kfree(mstate);
710}
711
712static void devm_mux_state_release(struct device *dev, void *res)
713{
714 struct mux_state *mstate = *(struct mux_state **)res;
715
716 mux_state_put(mstate);
717}
718
719/**
720 * devm_mux_state_get() - Get the mux-state for a device, with resource
721 * management.
722 * @dev: The device that needs a mux-control.
723 * @mux_name: The name identifying the mux-control.
724 *
725 * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
726 */
727struct mux_state *devm_mux_state_get(struct device *dev,
728 const char *mux_name)
729{
730 struct mux_state **ptr, *mstate;
731
732 ptr = devres_alloc(devm_mux_state_release, sizeof(*ptr), GFP_KERNEL);
733 if (!ptr)
734 return ERR_PTR(-ENOMEM);
735
736 mstate = mux_state_get(dev, mux_name);
737 if (IS_ERR(mstate)) {
738 devres_free(ptr);
739 return mstate;
740 }
741
742 *ptr = mstate;
743 devres_add(dev, ptr);
744
745 return mstate;
746}
747EXPORT_SYMBOL_GPL(devm_mux_state_get);
748
749/*
750 * Using subsys_initcall instead of module_init here to try to ensure - for
751 * the non-modular case - that the subsystem is initialized when mux consumers
752 * and mux controllers start to use it.
753 * For the modular case, the ordering is ensured with module dependencies.
754 */
755subsys_initcall(mux_init);
756module_exit(mux_exit);
757
758MODULE_DESCRIPTION("Multiplexer subsystem");
759MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
760MODULE_LICENSE("GPL v2");
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Multiplexer subsystem
4 *
5 * Copyright (C) 2017 Axentia Technologies AB
6 *
7 * Author: Peter Rosin <peda@axentia.se>
8 */
9
10#define pr_fmt(fmt) "mux-core: " fmt
11
12#include <linux/device.h>
13#include <linux/err.h>
14#include <linux/export.h>
15#include <linux/idr.h>
16#include <linux/init.h>
17#include <linux/module.h>
18#include <linux/mux/consumer.h>
19#include <linux/mux/driver.h>
20#include <linux/of.h>
21#include <linux/of_platform.h>
22#include <linux/slab.h>
23
24/*
25 * The idle-as-is "state" is not an actual state that may be selected, it
26 * only implies that the state should not be changed. So, use that state
27 * as indication that the cached state of the multiplexer is unknown.
28 */
29#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
30
31static struct class mux_class = {
32 .name = "mux",
33 .owner = THIS_MODULE,
34};
35
36static DEFINE_IDA(mux_ida);
37
38static int __init mux_init(void)
39{
40 ida_init(&mux_ida);
41 return class_register(&mux_class);
42}
43
44static void __exit mux_exit(void)
45{
46 class_unregister(&mux_class);
47 ida_destroy(&mux_ida);
48}
49
50static void mux_chip_release(struct device *dev)
51{
52 struct mux_chip *mux_chip = to_mux_chip(dev);
53
54 ida_simple_remove(&mux_ida, mux_chip->id);
55 kfree(mux_chip);
56}
57
58static const struct device_type mux_type = {
59 .name = "mux-chip",
60 .release = mux_chip_release,
61};
62
63/**
64 * mux_chip_alloc() - Allocate a mux-chip.
65 * @dev: The parent device implementing the mux interface.
66 * @controllers: The number of mux controllers to allocate for this chip.
67 * @sizeof_priv: Size of extra memory area for private use by the caller.
68 *
69 * After allocating the mux-chip with the desired number of mux controllers
70 * but before registering the chip, the mux driver is required to configure
71 * the number of valid mux states in the mux_chip->mux[N].states members and
72 * the desired idle state in the returned mux_chip->mux[N].idle_state members.
73 * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to
74 * provide a pointer to the operations struct in the mux_chip->ops member
75 * before registering the mux-chip with mux_chip_register.
76 *
77 * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
78 */
79struct mux_chip *mux_chip_alloc(struct device *dev,
80 unsigned int controllers, size_t sizeof_priv)
81{
82 struct mux_chip *mux_chip;
83 int i;
84
85 if (WARN_ON(!dev || !controllers))
86 return ERR_PTR(-EINVAL);
87
88 mux_chip = kzalloc(sizeof(*mux_chip) +
89 controllers * sizeof(*mux_chip->mux) +
90 sizeof_priv, GFP_KERNEL);
91 if (!mux_chip)
92 return ERR_PTR(-ENOMEM);
93
94 mux_chip->mux = (struct mux_control *)(mux_chip + 1);
95 mux_chip->dev.class = &mux_class;
96 mux_chip->dev.type = &mux_type;
97 mux_chip->dev.parent = dev;
98 mux_chip->dev.of_node = dev->of_node;
99 dev_set_drvdata(&mux_chip->dev, mux_chip);
100
101 mux_chip->id = ida_simple_get(&mux_ida, 0, 0, GFP_KERNEL);
102 if (mux_chip->id < 0) {
103 int err = mux_chip->id;
104
105 pr_err("muxchipX failed to get a device id\n");
106 kfree(mux_chip);
107 return ERR_PTR(err);
108 }
109 dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id);
110
111 mux_chip->controllers = controllers;
112 for (i = 0; i < controllers; ++i) {
113 struct mux_control *mux = &mux_chip->mux[i];
114
115 mux->chip = mux_chip;
116 sema_init(&mux->lock, 1);
117 mux->cached_state = MUX_CACHE_UNKNOWN;
118 mux->idle_state = MUX_IDLE_AS_IS;
119 }
120
121 device_initialize(&mux_chip->dev);
122
123 return mux_chip;
124}
125EXPORT_SYMBOL_GPL(mux_chip_alloc);
126
127static int mux_control_set(struct mux_control *mux, int state)
128{
129 int ret = mux->chip->ops->set(mux, state);
130
131 mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
132
133 return ret;
134}
135
136/**
137 * mux_chip_register() - Register a mux-chip, thus readying the controllers
138 * for use.
139 * @mux_chip: The mux-chip to register.
140 *
141 * Do not retry registration of the same mux-chip on failure. You should
142 * instead put it away with mux_chip_free() and allocate a new one, if you
143 * for some reason would like to retry registration.
144 *
145 * Return: Zero on success or a negative errno on error.
146 */
147int mux_chip_register(struct mux_chip *mux_chip)
148{
149 int i;
150 int ret;
151
152 for (i = 0; i < mux_chip->controllers; ++i) {
153 struct mux_control *mux = &mux_chip->mux[i];
154
155 if (mux->idle_state == mux->cached_state)
156 continue;
157
158 ret = mux_control_set(mux, mux->idle_state);
159 if (ret < 0) {
160 dev_err(&mux_chip->dev, "unable to set idle state\n");
161 return ret;
162 }
163 }
164
165 ret = device_add(&mux_chip->dev);
166 if (ret < 0)
167 dev_err(&mux_chip->dev,
168 "device_add failed in %s: %d\n", __func__, ret);
169 return ret;
170}
171EXPORT_SYMBOL_GPL(mux_chip_register);
172
173/**
174 * mux_chip_unregister() - Take the mux-chip off-line.
175 * @mux_chip: The mux-chip to unregister.
176 *
177 * mux_chip_unregister() reverses the effects of mux_chip_register().
178 * But not completely, you should not try to call mux_chip_register()
179 * on a mux-chip that has been registered before.
180 */
181void mux_chip_unregister(struct mux_chip *mux_chip)
182{
183 device_del(&mux_chip->dev);
184}
185EXPORT_SYMBOL_GPL(mux_chip_unregister);
186
187/**
188 * mux_chip_free() - Free the mux-chip for good.
189 * @mux_chip: The mux-chip to free.
190 *
191 * mux_chip_free() reverses the effects of mux_chip_alloc().
192 */
193void mux_chip_free(struct mux_chip *mux_chip)
194{
195 if (!mux_chip)
196 return;
197
198 put_device(&mux_chip->dev);
199}
200EXPORT_SYMBOL_GPL(mux_chip_free);
201
202static void devm_mux_chip_release(struct device *dev, void *res)
203{
204 struct mux_chip *mux_chip = *(struct mux_chip **)res;
205
206 mux_chip_free(mux_chip);
207}
208
209/**
210 * devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc().
211 * @dev: The parent device implementing the mux interface.
212 * @controllers: The number of mux controllers to allocate for this chip.
213 * @sizeof_priv: Size of extra memory area for private use by the caller.
214 *
215 * See mux_chip_alloc() for more details.
216 *
217 * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
218 */
219struct mux_chip *devm_mux_chip_alloc(struct device *dev,
220 unsigned int controllers,
221 size_t sizeof_priv)
222{
223 struct mux_chip **ptr, *mux_chip;
224
225 ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL);
226 if (!ptr)
227 return ERR_PTR(-ENOMEM);
228
229 mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv);
230 if (IS_ERR(mux_chip)) {
231 devres_free(ptr);
232 return mux_chip;
233 }
234
235 *ptr = mux_chip;
236 devres_add(dev, ptr);
237
238 return mux_chip;
239}
240EXPORT_SYMBOL_GPL(devm_mux_chip_alloc);
241
242static void devm_mux_chip_reg_release(struct device *dev, void *res)
243{
244 struct mux_chip *mux_chip = *(struct mux_chip **)res;
245
246 mux_chip_unregister(mux_chip);
247}
248
249/**
250 * devm_mux_chip_register() - Resource-managed version mux_chip_register().
251 * @dev: The parent device implementing the mux interface.
252 * @mux_chip: The mux-chip to register.
253 *
254 * See mux_chip_register() for more details.
255 *
256 * Return: Zero on success or a negative errno on error.
257 */
258int devm_mux_chip_register(struct device *dev,
259 struct mux_chip *mux_chip)
260{
261 struct mux_chip **ptr;
262 int res;
263
264 ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL);
265 if (!ptr)
266 return -ENOMEM;
267
268 res = mux_chip_register(mux_chip);
269 if (res) {
270 devres_free(ptr);
271 return res;
272 }
273
274 *ptr = mux_chip;
275 devres_add(dev, ptr);
276
277 return res;
278}
279EXPORT_SYMBOL_GPL(devm_mux_chip_register);
280
281/**
282 * mux_control_states() - Query the number of multiplexer states.
283 * @mux: The mux-control to query.
284 *
285 * Return: The number of multiplexer states.
286 */
287unsigned int mux_control_states(struct mux_control *mux)
288{
289 return mux->states;
290}
291EXPORT_SYMBOL_GPL(mux_control_states);
292
293/*
294 * The mux->lock must be down when calling this function.
295 */
296static int __mux_control_select(struct mux_control *mux, int state)
297{
298 int ret;
299
300 if (WARN_ON(state < 0 || state >= mux->states))
301 return -EINVAL;
302
303 if (mux->cached_state == state)
304 return 0;
305
306 ret = mux_control_set(mux, state);
307 if (ret >= 0)
308 return 0;
309
310 /* The mux update failed, try to revert if appropriate... */
311 if (mux->idle_state != MUX_IDLE_AS_IS)
312 mux_control_set(mux, mux->idle_state);
313
314 return ret;
315}
316
317/**
318 * mux_control_select() - Select the given multiplexer state.
319 * @mux: The mux-control to request a change of state from.
320 * @state: The new requested state.
321 *
322 * On successfully selecting the mux-control state, it will be locked until
323 * there is a call to mux_control_deselect(). If the mux-control is already
324 * selected when mux_control_select() is called, the caller will be blocked
325 * until mux_control_deselect() is called (by someone else).
326 *
327 * Therefore, make sure to call mux_control_deselect() when the operation is
328 * complete and the mux-control is free for others to use, but do not call
329 * mux_control_deselect() if mux_control_select() fails.
330 *
331 * Return: 0 when the mux-control state has the requested state or a negative
332 * errno on error.
333 */
334int mux_control_select(struct mux_control *mux, unsigned int state)
335{
336 int ret;
337
338 ret = down_killable(&mux->lock);
339 if (ret < 0)
340 return ret;
341
342 ret = __mux_control_select(mux, state);
343
344 if (ret < 0)
345 up(&mux->lock);
346
347 return ret;
348}
349EXPORT_SYMBOL_GPL(mux_control_select);
350
351/**
352 * mux_control_try_select() - Try to select the given multiplexer state.
353 * @mux: The mux-control to request a change of state from.
354 * @state: The new requested state.
355 *
356 * On successfully selecting the mux-control state, it will be locked until
357 * mux_control_deselect() called.
358 *
359 * Therefore, make sure to call mux_control_deselect() when the operation is
360 * complete and the mux-control is free for others to use, but do not call
361 * mux_control_deselect() if mux_control_try_select() fails.
362 *
363 * Return: 0 when the mux-control state has the requested state or a negative
364 * errno on error. Specifically -EBUSY if the mux-control is contended.
365 */
366int mux_control_try_select(struct mux_control *mux, unsigned int state)
367{
368 int ret;
369
370 if (down_trylock(&mux->lock))
371 return -EBUSY;
372
373 ret = __mux_control_select(mux, state);
374
375 if (ret < 0)
376 up(&mux->lock);
377
378 return ret;
379}
380EXPORT_SYMBOL_GPL(mux_control_try_select);
381
382/**
383 * mux_control_deselect() - Deselect the previously selected multiplexer state.
384 * @mux: The mux-control to deselect.
385 *
386 * It is required that a single call is made to mux_control_deselect() for
387 * each and every successful call made to either of mux_control_select() or
388 * mux_control_try_select().
389 *
390 * Return: 0 on success and a negative errno on error. An error can only
391 * occur if the mux has an idle state. Note that even if an error occurs, the
392 * mux-control is unlocked and is thus free for the next access.
393 */
394int mux_control_deselect(struct mux_control *mux)
395{
396 int ret = 0;
397
398 if (mux->idle_state != MUX_IDLE_AS_IS &&
399 mux->idle_state != mux->cached_state)
400 ret = mux_control_set(mux, mux->idle_state);
401
402 up(&mux->lock);
403
404 return ret;
405}
406EXPORT_SYMBOL_GPL(mux_control_deselect);
407
408/* Note this function returns a reference to the mux_chip dev. */
409static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
410{
411 struct device *dev;
412
413 dev = class_find_device_by_of_node(&mux_class, np);
414
415 return dev ? to_mux_chip(dev) : NULL;
416}
417
418/**
419 * mux_control_get() - Get the mux-control for a device.
420 * @dev: The device that needs a mux-control.
421 * @mux_name: The name identifying the mux-control.
422 *
423 * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
424 */
425struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
426{
427 struct device_node *np = dev->of_node;
428 struct of_phandle_args args;
429 struct mux_chip *mux_chip;
430 unsigned int controller;
431 int index = 0;
432 int ret;
433
434 if (mux_name) {
435 index = of_property_match_string(np, "mux-control-names",
436 mux_name);
437 if (index < 0) {
438 dev_err(dev, "mux controller '%s' not found\n",
439 mux_name);
440 return ERR_PTR(index);
441 }
442 }
443
444 ret = of_parse_phandle_with_args(np,
445 "mux-controls", "#mux-control-cells",
446 index, &args);
447 if (ret) {
448 dev_err(dev, "%pOF: failed to get mux-control %s(%i)\n",
449 np, mux_name ?: "", index);
450 return ERR_PTR(ret);
451 }
452
453 mux_chip = of_find_mux_chip_by_node(args.np);
454 of_node_put(args.np);
455 if (!mux_chip)
456 return ERR_PTR(-EPROBE_DEFER);
457
458 if (args.args_count > 1 ||
459 (!args.args_count && (mux_chip->controllers > 1))) {
460 dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n",
461 np, args.np);
462 put_device(&mux_chip->dev);
463 return ERR_PTR(-EINVAL);
464 }
465
466 controller = 0;
467 if (args.args_count)
468 controller = args.args[0];
469
470 if (controller >= mux_chip->controllers) {
471 dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n",
472 np, controller, args.np);
473 put_device(&mux_chip->dev);
474 return ERR_PTR(-EINVAL);
475 }
476
477 return &mux_chip->mux[controller];
478}
479EXPORT_SYMBOL_GPL(mux_control_get);
480
481/**
482 * mux_control_put() - Put away the mux-control for good.
483 * @mux: The mux-control to put away.
484 *
485 * mux_control_put() reverses the effects of mux_control_get().
486 */
487void mux_control_put(struct mux_control *mux)
488{
489 put_device(&mux->chip->dev);
490}
491EXPORT_SYMBOL_GPL(mux_control_put);
492
493static void devm_mux_control_release(struct device *dev, void *res)
494{
495 struct mux_control *mux = *(struct mux_control **)res;
496
497 mux_control_put(mux);
498}
499
500/**
501 * devm_mux_control_get() - Get the mux-control for a device, with resource
502 * management.
503 * @dev: The device that needs a mux-control.
504 * @mux_name: The name identifying the mux-control.
505 *
506 * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
507 */
508struct mux_control *devm_mux_control_get(struct device *dev,
509 const char *mux_name)
510{
511 struct mux_control **ptr, *mux;
512
513 ptr = devres_alloc(devm_mux_control_release, sizeof(*ptr), GFP_KERNEL);
514 if (!ptr)
515 return ERR_PTR(-ENOMEM);
516
517 mux = mux_control_get(dev, mux_name);
518 if (IS_ERR(mux)) {
519 devres_free(ptr);
520 return mux;
521 }
522
523 *ptr = mux;
524 devres_add(dev, ptr);
525
526 return mux;
527}
528EXPORT_SYMBOL_GPL(devm_mux_control_get);
529
530/*
531 * Using subsys_initcall instead of module_init here to try to ensure - for
532 * the non-modular case - that the subsystem is initialized when mux consumers
533 * and mux controllers start to use it.
534 * For the modular case, the ordering is ensured with module dependencies.
535 */
536subsys_initcall(mux_init);
537module_exit(mux_exit);
538
539MODULE_DESCRIPTION("Multiplexer subsystem");
540MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
541MODULE_LICENSE("GPL v2");