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1// SPDX-License-Identifier: GPL-2.02/*3 * Multiplexer subsystem4 *5 * Copyright (C) 2017 Axentia Technologies AB6 *7 * Author: Peter Rosin <peda@axentia.se>8 */9 10#define pr_fmt(fmt) "mux-core: " fmt11 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, it26 * only implies that the state should not be changed. So, use that state27 * as indication that the cached state of the multiplexer is unknown.28 */29#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS30 31/**32 * struct mux_state - Represents a mux controller state specific to a given33 * 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 has38 * 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_free(&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 controllers83 * but before registering the chip, the mux driver is required to configure84 * the number of valid mux states in the mux_chip->mux[N].states members and85 * 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 to87 * provide a pointer to the operations struct in the mux_chip->ops member88 * 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_alloc(&mux_ida, 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 controllers154 * for use.155 * @mux_chip: The mux-chip to register.156 *157 * Do not retry registration of the same mux-chip on failure. You should158 * instead put it away with mux_chip_free() and allocate a new one, if you159 * 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 until354 * there is a call to mux_control_deselect(). If the mux-control is already355 * selected when mux_control_select() is called, the caller will be blocked356 * until mux_control_deselect() or mux_state_deselect() is called (by someone357 * else).358 *359 * Therefore, make sure to call mux_control_deselect() when the operation is360 * complete and the mux-control is free for others to use, but do not call361 * mux_control_deselect() if mux_control_select() fails.362 *363 * Return: 0 when the mux-control state has the requested state or a negative364 * 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 locked392 * until there is a call to mux_state_deselect(). If the mux-control is already393 * selected when mux_state_select() is called, the caller will be blocked394 * until mux_state_deselect() or mux_control_deselect() is called (by someone395 * else).396 *397 * Therefore, make sure to call mux_state_deselect() when the operation is398 * complete and the mux-control is free for others to use, but do not call399 * mux_state_deselect() if mux_state_select() fails.400 *401 * Return: 0 when the mux-state has been selected or a negative402 * 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 until417 * mux_control_deselect() is called.418 *419 * Therefore, make sure to call mux_control_deselect() when the operation is420 * complete and the mux-control is free for others to use, but do not call421 * mux_control_deselect() if mux_control_try_select() fails.422 *423 * Return: 0 when the mux-control state has the requested state or a negative424 * 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 locked451 * until mux_state_deselect() is called.452 *453 * Therefore, make sure to call mux_state_deselect() when the operation is454 * complete and the mux-control is free for others to use, but do not call455 * mux_state_deselect() if mux_state_try_select() fails.456 *457 * Return: 0 when the mux-state has been selected or a negative errno on458 * 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() for471 * each and every successful call made to either of mux_control_select() or472 * mux_control_try_select().473 *474 * Return: 0 on success and a negative errno on error. An error can only475 * occur if the mux has an idle state. Note that even if an error occurs, the476 * 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() for497 * each and every successful call made to either of mux_state_select() or498 * mux_state_try_select().499 *500 * Return: 0 on success and a negative errno on error. An error can only501 * occur if the mux has an idle state. Note that even if an error occurs, the502 * 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 when525 * 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 else544 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 else558 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 resource646 * 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 resource721 * 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 - for751 * the non-modular case - that the subsystem is initialized when mux consumers752 * 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");761