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a3b02a9c PR |
1 | /* |
2 | * Multiplexer subsystem | |
3 | * | |
4 | * Copyright (C) 2017 Axentia Technologies AB | |
5 | * | |
6 | * Author: Peter Rosin <peda@axentia.se> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | */ | |
12 | ||
13 | #define pr_fmt(fmt) "mux-core: " fmt | |
14 | ||
15 | #include <linux/device.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/export.h> | |
18 | #include <linux/idr.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/mux/consumer.h> | |
22 | #include <linux/mux/driver.h> | |
23 | #include <linux/of.h> | |
24 | #include <linux/of_platform.h> | |
25 | #include <linux/slab.h> | |
26 | ||
27 | /* | |
28 | * The idle-as-is "state" is not an actual state that may be selected, it | |
29 | * only implies that the state should not be changed. So, use that state | |
30 | * as indication that the cached state of the multiplexer is unknown. | |
31 | */ | |
32 | #define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS | |
33 | ||
34 | static struct class mux_class = { | |
35 | .name = "mux", | |
36 | .owner = THIS_MODULE, | |
37 | }; | |
38 | ||
39 | static DEFINE_IDA(mux_ida); | |
40 | ||
41 | static int __init mux_init(void) | |
42 | { | |
43 | ida_init(&mux_ida); | |
44 | return class_register(&mux_class); | |
45 | } | |
46 | ||
47 | static void __exit mux_exit(void) | |
48 | { | |
99884996 | 49 | class_unregister(&mux_class); |
a3b02a9c PR |
50 | ida_destroy(&mux_ida); |
51 | } | |
52 | ||
53 | static void mux_chip_release(struct device *dev) | |
54 | { | |
55 | struct mux_chip *mux_chip = to_mux_chip(dev); | |
56 | ||
57 | ida_simple_remove(&mux_ida, mux_chip->id); | |
58 | kfree(mux_chip); | |
59 | } | |
60 | ||
a49c3fee | 61 | static const struct device_type mux_type = { |
a3b02a9c PR |
62 | .name = "mux-chip", |
63 | .release = mux_chip_release, | |
64 | }; | |
65 | ||
66 | /** | |
67 | * mux_chip_alloc() - Allocate a mux-chip. | |
68 | * @dev: The parent device implementing the mux interface. | |
69 | * @controllers: The number of mux controllers to allocate for this chip. | |
70 | * @sizeof_priv: Size of extra memory area for private use by the caller. | |
71 | * | |
72 | * After allocating the mux-chip with the desired number of mux controllers | |
73 | * but before registering the chip, the mux driver is required to configure | |
74 | * the number of valid mux states in the mux_chip->mux[N].states members and | |
75 | * the desired idle state in the returned mux_chip->mux[N].idle_state members. | |
76 | * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to | |
77 | * provide a pointer to the operations struct in the mux_chip->ops member | |
78 | * before registering the mux-chip with mux_chip_register. | |
79 | * | |
80 | * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. | |
81 | */ | |
82 | struct mux_chip *mux_chip_alloc(struct device *dev, | |
83 | unsigned int controllers, size_t sizeof_priv) | |
84 | { | |
85 | struct mux_chip *mux_chip; | |
86 | int i; | |
87 | ||
88 | if (WARN_ON(!dev || !controllers)) | |
89 | return ERR_PTR(-EINVAL); | |
90 | ||
91 | mux_chip = kzalloc(sizeof(*mux_chip) + | |
92 | controllers * sizeof(*mux_chip->mux) + | |
93 | sizeof_priv, GFP_KERNEL); | |
94 | if (!mux_chip) | |
95 | return ERR_PTR(-ENOMEM); | |
96 | ||
97 | mux_chip->mux = (struct mux_control *)(mux_chip + 1); | |
98 | mux_chip->dev.class = &mux_class; | |
99 | mux_chip->dev.type = &mux_type; | |
100 | mux_chip->dev.parent = dev; | |
101 | mux_chip->dev.of_node = dev->of_node; | |
102 | dev_set_drvdata(&mux_chip->dev, mux_chip); | |
103 | ||
104 | mux_chip->id = ida_simple_get(&mux_ida, 0, 0, GFP_KERNEL); | |
105 | if (mux_chip->id < 0) { | |
106 | int err = mux_chip->id; | |
107 | ||
108 | pr_err("muxchipX failed to get a device id\n"); | |
109 | kfree(mux_chip); | |
110 | return ERR_PTR(err); | |
111 | } | |
112 | dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id); | |
113 | ||
114 | mux_chip->controllers = controllers; | |
115 | for (i = 0; i < controllers; ++i) { | |
116 | struct mux_control *mux = &mux_chip->mux[i]; | |
117 | ||
118 | mux->chip = mux_chip; | |
119 | sema_init(&mux->lock, 1); | |
120 | mux->cached_state = MUX_CACHE_UNKNOWN; | |
121 | mux->idle_state = MUX_IDLE_AS_IS; | |
122 | } | |
123 | ||
124 | device_initialize(&mux_chip->dev); | |
125 | ||
126 | return mux_chip; | |
127 | } | |
128 | EXPORT_SYMBOL_GPL(mux_chip_alloc); | |
129 | ||
130 | static int mux_control_set(struct mux_control *mux, int state) | |
131 | { | |
132 | int ret = mux->chip->ops->set(mux, state); | |
133 | ||
134 | mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state; | |
135 | ||
136 | return ret; | |
137 | } | |
138 | ||
139 | /** | |
140 | * mux_chip_register() - Register a mux-chip, thus readying the controllers | |
141 | * for use. | |
142 | * @mux_chip: The mux-chip to register. | |
143 | * | |
144 | * Do not retry registration of the same mux-chip on failure. You should | |
145 | * instead put it away with mux_chip_free() and allocate a new one, if you | |
146 | * for some reason would like to retry registration. | |
147 | * | |
148 | * Return: Zero on success or a negative errno on error. | |
149 | */ | |
150 | int mux_chip_register(struct mux_chip *mux_chip) | |
151 | { | |
152 | int i; | |
153 | int ret; | |
154 | ||
155 | for (i = 0; i < mux_chip->controllers; ++i) { | |
156 | struct mux_control *mux = &mux_chip->mux[i]; | |
157 | ||
158 | if (mux->idle_state == mux->cached_state) | |
159 | continue; | |
160 | ||
161 | ret = mux_control_set(mux, mux->idle_state); | |
162 | if (ret < 0) { | |
163 | dev_err(&mux_chip->dev, "unable to set idle state\n"); | |
164 | return ret; | |
165 | } | |
166 | } | |
167 | ||
168 | ret = device_add(&mux_chip->dev); | |
169 | if (ret < 0) | |
170 | dev_err(&mux_chip->dev, | |
171 | "device_add failed in %s: %d\n", __func__, ret); | |
172 | return ret; | |
173 | } | |
174 | EXPORT_SYMBOL_GPL(mux_chip_register); | |
175 | ||
176 | /** | |
177 | * mux_chip_unregister() - Take the mux-chip off-line. | |
178 | * @mux_chip: The mux-chip to unregister. | |
179 | * | |
180 | * mux_chip_unregister() reverses the effects of mux_chip_register(). | |
181 | * But not completely, you should not try to call mux_chip_register() | |
182 | * on a mux-chip that has been registered before. | |
183 | */ | |
184 | void mux_chip_unregister(struct mux_chip *mux_chip) | |
185 | { | |
186 | device_del(&mux_chip->dev); | |
187 | } | |
188 | EXPORT_SYMBOL_GPL(mux_chip_unregister); | |
189 | ||
190 | /** | |
191 | * mux_chip_free() - Free the mux-chip for good. | |
192 | * @mux_chip: The mux-chip to free. | |
193 | * | |
194 | * mux_chip_free() reverses the effects of mux_chip_alloc(). | |
195 | */ | |
196 | void mux_chip_free(struct mux_chip *mux_chip) | |
197 | { | |
198 | if (!mux_chip) | |
199 | return; | |
200 | ||
201 | put_device(&mux_chip->dev); | |
202 | } | |
203 | EXPORT_SYMBOL_GPL(mux_chip_free); | |
204 | ||
205 | static void devm_mux_chip_release(struct device *dev, void *res) | |
206 | { | |
207 | struct mux_chip *mux_chip = *(struct mux_chip **)res; | |
208 | ||
209 | mux_chip_free(mux_chip); | |
210 | } | |
211 | ||
212 | /** | |
213 | * devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc(). | |
214 | * @dev: The parent device implementing the mux interface. | |
215 | * @controllers: The number of mux controllers to allocate for this chip. | |
216 | * @sizeof_priv: Size of extra memory area for private use by the caller. | |
217 | * | |
218 | * See mux_chip_alloc() for more details. | |
219 | * | |
220 | * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. | |
221 | */ | |
222 | struct mux_chip *devm_mux_chip_alloc(struct device *dev, | |
223 | unsigned int controllers, | |
224 | size_t sizeof_priv) | |
225 | { | |
226 | struct mux_chip **ptr, *mux_chip; | |
227 | ||
228 | ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL); | |
229 | if (!ptr) | |
230 | return ERR_PTR(-ENOMEM); | |
231 | ||
232 | mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv); | |
233 | if (IS_ERR(mux_chip)) { | |
234 | devres_free(ptr); | |
235 | return mux_chip; | |
236 | } | |
237 | ||
238 | *ptr = mux_chip; | |
239 | devres_add(dev, ptr); | |
240 | ||
241 | return mux_chip; | |
242 | } | |
243 | EXPORT_SYMBOL_GPL(devm_mux_chip_alloc); | |
244 | ||
245 | static void devm_mux_chip_reg_release(struct device *dev, void *res) | |
246 | { | |
247 | struct mux_chip *mux_chip = *(struct mux_chip **)res; | |
248 | ||
249 | mux_chip_unregister(mux_chip); | |
250 | } | |
251 | ||
252 | /** | |
253 | * devm_mux_chip_register() - Resource-managed version mux_chip_register(). | |
254 | * @dev: The parent device implementing the mux interface. | |
255 | * @mux_chip: The mux-chip to register. | |
256 | * | |
257 | * See mux_chip_register() for more details. | |
258 | * | |
259 | * Return: Zero on success or a negative errno on error. | |
260 | */ | |
261 | int devm_mux_chip_register(struct device *dev, | |
262 | struct mux_chip *mux_chip) | |
263 | { | |
264 | struct mux_chip **ptr; | |
265 | int res; | |
266 | ||
267 | ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL); | |
268 | if (!ptr) | |
269 | return -ENOMEM; | |
270 | ||
271 | res = mux_chip_register(mux_chip); | |
272 | if (res) { | |
273 | devres_free(ptr); | |
274 | return res; | |
275 | } | |
276 | ||
277 | *ptr = mux_chip; | |
278 | devres_add(dev, ptr); | |
279 | ||
280 | return res; | |
281 | } | |
282 | EXPORT_SYMBOL_GPL(devm_mux_chip_register); | |
283 | ||
284 | /** | |
285 | * mux_control_states() - Query the number of multiplexer states. | |
286 | * @mux: The mux-control to query. | |
287 | * | |
288 | * Return: The number of multiplexer states. | |
289 | */ | |
290 | unsigned int mux_control_states(struct mux_control *mux) | |
291 | { | |
292 | return mux->states; | |
293 | } | |
294 | EXPORT_SYMBOL_GPL(mux_control_states); | |
295 | ||
296 | /* | |
297 | * The mux->lock must be down when calling this function. | |
298 | */ | |
299 | static int __mux_control_select(struct mux_control *mux, int state) | |
300 | { | |
301 | int ret; | |
302 | ||
303 | if (WARN_ON(state < 0 || state >= mux->states)) | |
304 | return -EINVAL; | |
305 | ||
306 | if (mux->cached_state == state) | |
307 | return 0; | |
308 | ||
309 | ret = mux_control_set(mux, state); | |
310 | if (ret >= 0) | |
311 | return 0; | |
312 | ||
313 | /* The mux update failed, try to revert if appropriate... */ | |
314 | if (mux->idle_state != MUX_IDLE_AS_IS) | |
315 | mux_control_set(mux, mux->idle_state); | |
316 | ||
317 | return ret; | |
318 | } | |
319 | ||
320 | /** | |
321 | * mux_control_select() - Select the given multiplexer state. | |
322 | * @mux: The mux-control to request a change of state from. | |
323 | * @state: The new requested state. | |
324 | * | |
325 | * On successfully selecting the mux-control state, it will be locked until | |
326 | * there is a call to mux_control_deselect(). If the mux-control is already | |
327 | * selected when mux_control_select() is called, the caller will be blocked | |
328 | * until mux_control_deselect() is called (by someone else). | |
329 | * | |
330 | * Therefore, make sure to call mux_control_deselect() when the operation is | |
331 | * complete and the mux-control is free for others to use, but do not call | |
332 | * mux_control_deselect() if mux_control_select() fails. | |
333 | * | |
334 | * Return: 0 when the mux-control state has the requested state or a negative | |
335 | * errno on error. | |
336 | */ | |
337 | int mux_control_select(struct mux_control *mux, unsigned int state) | |
338 | { | |
339 | int ret; | |
340 | ||
341 | ret = down_killable(&mux->lock); | |
342 | if (ret < 0) | |
343 | return ret; | |
344 | ||
345 | ret = __mux_control_select(mux, state); | |
346 | ||
347 | if (ret < 0) | |
348 | up(&mux->lock); | |
349 | ||
350 | return ret; | |
351 | } | |
352 | EXPORT_SYMBOL_GPL(mux_control_select); | |
353 | ||
354 | /** | |
355 | * mux_control_try_select() - Try to select the given multiplexer state. | |
356 | * @mux: The mux-control to request a change of state from. | |
357 | * @state: The new requested state. | |
358 | * | |
359 | * On successfully selecting the mux-control state, it will be locked until | |
360 | * mux_control_deselect() called. | |
361 | * | |
362 | * Therefore, make sure to call mux_control_deselect() when the operation is | |
363 | * complete and the mux-control is free for others to use, but do not call | |
364 | * mux_control_deselect() if mux_control_try_select() fails. | |
365 | * | |
366 | * Return: 0 when the mux-control state has the requested state or a negative | |
367 | * errno on error. Specifically -EBUSY if the mux-control is contended. | |
368 | */ | |
369 | int mux_control_try_select(struct mux_control *mux, unsigned int state) | |
370 | { | |
371 | int ret; | |
372 | ||
373 | if (down_trylock(&mux->lock)) | |
374 | return -EBUSY; | |
375 | ||
376 | ret = __mux_control_select(mux, state); | |
377 | ||
378 | if (ret < 0) | |
379 | up(&mux->lock); | |
380 | ||
381 | return ret; | |
382 | } | |
383 | EXPORT_SYMBOL_GPL(mux_control_try_select); | |
384 | ||
385 | /** | |
386 | * mux_control_deselect() - Deselect the previously selected multiplexer state. | |
387 | * @mux: The mux-control to deselect. | |
388 | * | |
389 | * It is required that a single call is made to mux_control_deselect() for | |
390 | * each and every successful call made to either of mux_control_select() or | |
391 | * mux_control_try_select(). | |
392 | * | |
393 | * Return: 0 on success and a negative errno on error. An error can only | |
394 | * occur if the mux has an idle state. Note that even if an error occurs, the | |
395 | * mux-control is unlocked and is thus free for the next access. | |
396 | */ | |
397 | int mux_control_deselect(struct mux_control *mux) | |
398 | { | |
399 | int ret = 0; | |
400 | ||
401 | if (mux->idle_state != MUX_IDLE_AS_IS && | |
402 | mux->idle_state != mux->cached_state) | |
403 | ret = mux_control_set(mux, mux->idle_state); | |
404 | ||
405 | up(&mux->lock); | |
406 | ||
407 | return ret; | |
408 | } | |
409 | EXPORT_SYMBOL_GPL(mux_control_deselect); | |
410 | ||
411 | static int of_dev_node_match(struct device *dev, const void *data) | |
412 | { | |
413 | return dev->of_node == data; | |
414 | } | |
415 | ||
aa1f10e8 | 416 | /* Note this function returns a reference to the mux_chip dev. */ |
a3b02a9c PR |
417 | static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np) |
418 | { | |
419 | struct device *dev; | |
420 | ||
421 | dev = class_find_device(&mux_class, NULL, np, of_dev_node_match); | |
422 | ||
423 | return dev ? to_mux_chip(dev) : NULL; | |
424 | } | |
425 | ||
426 | /** | |
427 | * mux_control_get() - Get the mux-control for a device. | |
428 | * @dev: The device that needs a mux-control. | |
429 | * @mux_name: The name identifying the mux-control. | |
430 | * | |
431 | * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno. | |
432 | */ | |
433 | struct mux_control *mux_control_get(struct device *dev, const char *mux_name) | |
434 | { | |
435 | struct device_node *np = dev->of_node; | |
436 | struct of_phandle_args args; | |
437 | struct mux_chip *mux_chip; | |
438 | unsigned int controller; | |
439 | int index = 0; | |
440 | int ret; | |
441 | ||
442 | if (mux_name) { | |
443 | index = of_property_match_string(np, "mux-control-names", | |
444 | mux_name); | |
445 | if (index < 0) { | |
446 | dev_err(dev, "mux controller '%s' not found\n", | |
447 | mux_name); | |
448 | return ERR_PTR(index); | |
449 | } | |
450 | } | |
451 | ||
452 | ret = of_parse_phandle_with_args(np, | |
453 | "mux-controls", "#mux-control-cells", | |
454 | index, &args); | |
455 | if (ret) { | |
c398bc9b RH |
456 | dev_err(dev, "%pOF: failed to get mux-control %s(%i)\n", |
457 | np, mux_name ?: "", index); | |
a3b02a9c PR |
458 | return ERR_PTR(ret); |
459 | } | |
460 | ||
461 | mux_chip = of_find_mux_chip_by_node(args.np); | |
462 | of_node_put(args.np); | |
463 | if (!mux_chip) | |
464 | return ERR_PTR(-EPROBE_DEFER); | |
465 | ||
466 | if (args.args_count > 1 || | |
467 | (!args.args_count && (mux_chip->controllers > 1))) { | |
c398bc9b RH |
468 | dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n", |
469 | np, args.np); | |
aa1f10e8 | 470 | put_device(&mux_chip->dev); |
a3b02a9c PR |
471 | return ERR_PTR(-EINVAL); |
472 | } | |
473 | ||
474 | controller = 0; | |
475 | if (args.args_count) | |
476 | controller = args.args[0]; | |
477 | ||
478 | if (controller >= mux_chip->controllers) { | |
c398bc9b RH |
479 | dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n", |
480 | np, controller, args.np); | |
aa1f10e8 | 481 | put_device(&mux_chip->dev); |
a3b02a9c PR |
482 | return ERR_PTR(-EINVAL); |
483 | } | |
484 | ||
a3b02a9c PR |
485 | return &mux_chip->mux[controller]; |
486 | } | |
487 | EXPORT_SYMBOL_GPL(mux_control_get); | |
488 | ||
489 | /** | |
490 | * mux_control_put() - Put away the mux-control for good. | |
491 | * @mux: The mux-control to put away. | |
492 | * | |
493 | * mux_control_put() reverses the effects of mux_control_get(). | |
494 | */ | |
495 | void mux_control_put(struct mux_control *mux) | |
496 | { | |
497 | put_device(&mux->chip->dev); | |
498 | } | |
499 | EXPORT_SYMBOL_GPL(mux_control_put); | |
500 | ||
501 | static void devm_mux_control_release(struct device *dev, void *res) | |
502 | { | |
503 | struct mux_control *mux = *(struct mux_control **)res; | |
504 | ||
505 | mux_control_put(mux); | |
506 | } | |
507 | ||
508 | /** | |
509 | * devm_mux_control_get() - Get the mux-control for a device, with resource | |
510 | * management. | |
511 | * @dev: The device that needs a mux-control. | |
512 | * @mux_name: The name identifying the mux-control. | |
513 | * | |
514 | * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno. | |
515 | */ | |
516 | struct mux_control *devm_mux_control_get(struct device *dev, | |
517 | const char *mux_name) | |
518 | { | |
519 | struct mux_control **ptr, *mux; | |
520 | ||
521 | ptr = devres_alloc(devm_mux_control_release, sizeof(*ptr), GFP_KERNEL); | |
522 | if (!ptr) | |
523 | return ERR_PTR(-ENOMEM); | |
524 | ||
525 | mux = mux_control_get(dev, mux_name); | |
526 | if (IS_ERR(mux)) { | |
527 | devres_free(ptr); | |
528 | return mux; | |
529 | } | |
530 | ||
531 | *ptr = mux; | |
532 | devres_add(dev, ptr); | |
533 | ||
534 | return mux; | |
535 | } | |
536 | EXPORT_SYMBOL_GPL(devm_mux_control_get); | |
537 | ||
538 | /* | |
539 | * Using subsys_initcall instead of module_init here to try to ensure - for | |
540 | * the non-modular case - that the subsystem is initialized when mux consumers | |
541 | * and mux controllers start to use it. | |
542 | * For the modular case, the ordering is ensured with module dependencies. | |
543 | */ | |
544 | subsys_initcall(mux_init); | |
545 | module_exit(mux_exit); | |
546 | ||
547 | MODULE_DESCRIPTION("Multiplexer subsystem"); | |
548 | MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); | |
549 | MODULE_LICENSE("GPL v2"); |