// SPDX-License-Identifier: GPL-2.0/* * Multiplexer subsystem * * Copyright (C) 2017 Axentia Technologies AB * * Author: Peter Rosin <peda@axentia.se> */ #define pr_fmt(fmt) "mux-core: " fmt #include <linux/delay.h>#include <linux/device.h>#include <linux/err.h>#include <linux/export.h>#include <linux/idr.h>#include <linux/init.h>#include <linux/module.h>#include <linux/mux/consumer.h>#include <linux/mux/driver.h>#include <linux/of.h>#include <linux/slab.h> /* * The idle-as-is "state" is not an actual state that may be selected, it * only implies that the state should not be changed. So, use that state * as indication that the cached state of the multiplexer is unknown. */#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS /** * struct mux_state - Represents a mux controller state specific to a given * consumer. * @mux: Pointer to a mux controller. * @state: State of the mux to be selected. * * This structure is specific to the consumer that acquires it and has * information specific to that consumer. */struct mux_state { struct mux_control *mux; unsigned int state;}; static const struct class mux_class = { .name = "mux",}; /** * struct devm_mux_state_state - Tracks managed resources for mux-state objects. * @mstate: Pointer to a mux state. * @exit: An optional callback to execute before free. */struct devm_mux_state_state { struct mux_state *mstate; int (*exit)(struct mux_state *mstate);}; static DEFINE_IDA(mux_ida); static int __init mux_init(void){ ida_init(&mux_ida); return class_register(&mux_class);} static void __exit mux_exit(void){ class_unregister(&mux_class); ida_destroy(&mux_ida);} static void mux_chip_release(struct device *dev){ struct mux_chip *mux_chip = to_mux_chip(dev); ida_free(&mux_ida, mux_chip->id); kfree(mux_chip);} static const struct device_type mux_type = { .name = "mux-chip", .release = mux_chip_release,}; /** * mux_chip_alloc() - Allocate a mux-chip. * @dev: The parent device implementing the mux interface. * @controllers: The number of mux controllers to allocate for this chip. * @sizeof_priv: Size of extra memory area for private use by the caller. * * After allocating the mux-chip with the desired number of mux controllers * but before registering the chip, the mux driver is required to configure * the number of valid mux states in the mux_chip->mux[N].states members and * the desired idle state in the returned mux_chip->mux[N].idle_state members. * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to * provide a pointer to the operations struct in the mux_chip->ops member * before registering the mux-chip with mux_chip_register. * * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. */struct mux_chip *mux_chip_alloc(struct device *dev, unsigned int controllers, size_t sizeof_priv){ struct mux_chip *mux_chip; int i; if (WARN_ON(!dev || !controllers)) return ERR_PTR(-EINVAL); mux_chip = kzalloc(size_add(struct_size(mux_chip, mux, controllers), sizeof_priv), GFP_KERNEL); if (!mux_chip) return ERR_PTR(-ENOMEM); mux_chip->dev.class = &mux_class; mux_chip->dev.type = &mux_type; mux_chip->dev.parent = dev; mux_chip->dev.of_node = dev->of_node; dev_set_drvdata(&mux_chip->dev, mux_chip); mux_chip->id = ida_alloc(&mux_ida, GFP_KERNEL); if (mux_chip->id < 0) { int err = mux_chip->id; pr_err("muxchipX failed to get a device id\n"); kfree(mux_chip); return ERR_PTR(err); } dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id); mux_chip->controllers = controllers; for (i = 0; i < controllers; ++i) { struct mux_control *mux = &mux_chip->mux[i]; mux->chip = mux_chip; sema_init(&mux->lock, 1); mux->cached_state = MUX_CACHE_UNKNOWN; mux->idle_state = MUX_IDLE_AS_IS; mux->last_change = ktime_get(); } device_initialize(&mux_chip->dev); return mux_chip;}EXPORT_SYMBOL_GPL(mux_chip_alloc); static int mux_control_set(struct mux_control *mux, int state){ int ret = mux->chip->ops->set(mux, state); mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state; if (ret >= 0) mux->last_change = ktime_get(); return ret;} /** * mux_chip_register() - Register a mux-chip, thus readying the controllers * for use. * @mux_chip: The mux-chip to register. * * Do not retry registration of the same mux-chip on failure. You should * instead put it away with mux_chip_free() and allocate a new one, if you * for some reason would like to retry registration. * * Return: Zero on success or a negative errno on error. */int mux_chip_register(struct mux_chip *mux_chip){ int i; int ret; for (i = 0; i < mux_chip->controllers; ++i) { struct mux_control *mux = &mux_chip->mux[i]; if (mux->idle_state == mux->cached_state) continue; ret = mux_control_set(mux, mux->idle_state); if (ret < 0) { dev_err(&mux_chip->dev, "unable to set idle state\n"); return ret; } } ret = device_add(&mux_chip->dev); if (ret < 0) dev_err(&mux_chip->dev, "device_add failed in %s: %d\n", __func__, ret); return ret;}EXPORT_SYMBOL_GPL(mux_chip_register); /** * mux_chip_unregister() - Take the mux-chip off-line. * @mux_chip: The mux-chip to unregister. * * mux_chip_unregister() reverses the effects of mux_chip_register(). * But not completely, you should not try to call mux_chip_register() * on a mux-chip that has been registered before. */void mux_chip_unregister(struct mux_chip *mux_chip){ device_del(&mux_chip->dev);}EXPORT_SYMBOL_GPL(mux_chip_unregister); /** * mux_chip_free() - Free the mux-chip for good. * @mux_chip: The mux-chip to free. * * mux_chip_free() reverses the effects of mux_chip_alloc(). */void mux_chip_free(struct mux_chip *mux_chip){ if (!mux_chip) return; put_device(&mux_chip->dev);}EXPORT_SYMBOL_GPL(mux_chip_free); static void devm_mux_chip_release(struct device *dev, void *res){ struct mux_chip *mux_chip = *(struct mux_chip **)res; mux_chip_free(mux_chip);} /** * devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc(). * @dev: The parent device implementing the mux interface. * @controllers: The number of mux controllers to allocate for this chip. * @sizeof_priv: Size of extra memory area for private use by the caller. * * See mux_chip_alloc() for more details. * * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. */struct mux_chip *devm_mux_chip_alloc(struct device *dev, unsigned int controllers, size_t sizeof_priv){ struct mux_chip **ptr, *mux_chip; ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv); if (IS_ERR(mux_chip)) { devres_free(ptr); return mux_chip; } *ptr = mux_chip; devres_add(dev, ptr); return mux_chip;}EXPORT_SYMBOL_GPL(devm_mux_chip_alloc); static void devm_mux_chip_reg_release(struct device *dev, void *res){ struct mux_chip *mux_chip = *(struct mux_chip **)res; mux_chip_unregister(mux_chip);} /** * devm_mux_chip_register() - Resource-managed version mux_chip_register(). * @dev: The parent device implementing the mux interface. * @mux_chip: The mux-chip to register. * * See mux_chip_register() for more details. * * Return: Zero on success or a negative errno on error. */int devm_mux_chip_register(struct device *dev, struct mux_chip *mux_chip){ struct mux_chip **ptr; int res; ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return -ENOMEM; res = mux_chip_register(mux_chip); if (res) { devres_free(ptr); return res; } *ptr = mux_chip; devres_add(dev, ptr); return res;}EXPORT_SYMBOL_GPL(devm_mux_chip_register); /** * mux_control_states() - Query the number of multiplexer states. * @mux: The mux-control to query. * * Return: The number of multiplexer states. */unsigned int mux_control_states(struct mux_control *mux){ return mux->states;}EXPORT_SYMBOL_GPL(mux_control_states); /* * The mux->lock must be down when calling this function. */static int __mux_control_select(struct mux_control *mux, int state){ int ret; if (WARN_ON(state < 0 || state >= mux->states)) return -EINVAL; if (mux->cached_state == state) return 0; ret = mux_control_set(mux, state); if (ret >= 0) return 0; /* The mux update failed, try to revert if appropriate... */ if (mux->idle_state != MUX_IDLE_AS_IS) mux_control_set(mux, mux->idle_state); return ret;} static void mux_control_delay(struct mux_control *mux, unsigned int delay_us){ ktime_t delayend; s64 remaining; if (!delay_us) return; delayend = ktime_add_us(mux->last_change, delay_us); remaining = ktime_us_delta(delayend, ktime_get()); if (remaining > 0) fsleep(remaining);} /** * mux_control_select_delay() - Select the given multiplexer state. * @mux: The mux-control to request a change of state from. * @state: The new requested state. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-control state, it will be locked until * there is a call to mux_control_deselect(). If the mux-control is already * selected when mux_control_select() is called, the caller will be blocked * until mux_control_deselect() or mux_state_deselect() is called (by someone * else). * * Therefore, make sure to call mux_control_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_control_deselect() if mux_control_select() fails. * * Return: 0 when the mux-control state has the requested state or a negative * errno on error. */int mux_control_select_delay(struct mux_control *mux, unsigned int state, unsigned int delay_us){ int ret; ret = down_killable(&mux->lock); if (ret < 0) return ret; ret = __mux_control_select(mux, state); if (ret >= 0) mux_control_delay(mux, delay_us); if (ret < 0) up(&mux->lock); return ret;}EXPORT_SYMBOL_GPL(mux_control_select_delay); /** * mux_state_select_delay() - Select the given multiplexer state. * @mstate: The mux-state to select. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-state, its mux-control will be locked * until there is a call to mux_state_deselect(). If the mux-control is already * selected when mux_state_select() is called, the caller will be blocked * until mux_state_deselect() or mux_control_deselect() is called (by someone * else). * * Therefore, make sure to call mux_state_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_state_deselect() if mux_state_select() fails. * * Return: 0 when the mux-state has been selected or a negative * errno on error. */int mux_state_select_delay(struct mux_state *mstate, unsigned int delay_us){ return mux_control_select_delay(mstate->mux, mstate->state, delay_us);}EXPORT_SYMBOL_GPL(mux_state_select_delay); /** * mux_control_try_select_delay() - Try to select the given multiplexer state. * @mux: The mux-control to request a change of state from. * @state: The new requested state. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-control state, it will be locked until * mux_control_deselect() is called. * * Therefore, make sure to call mux_control_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_control_deselect() if mux_control_try_select() fails. * * Return: 0 when the mux-control state has the requested state or a negative * errno on error. Specifically -EBUSY if the mux-control is contended. */int mux_control_try_select_delay(struct mux_control *mux, unsigned int state, unsigned int delay_us){ int ret; if (down_trylock(&mux->lock)) return -EBUSY; ret = __mux_control_select(mux, state); if (ret >= 0) mux_control_delay(mux, delay_us); if (ret < 0) up(&mux->lock); return ret;}EXPORT_SYMBOL_GPL(mux_control_try_select_delay); /** * mux_state_try_select_delay() - Try to select the given multiplexer state. * @mstate: The mux-state to select. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-state, its mux-control will be locked * until mux_state_deselect() is called. * * Therefore, make sure to call mux_state_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_state_deselect() if mux_state_try_select() fails. * * Return: 0 when the mux-state has been selected or a negative errno on * error. Specifically -EBUSY if the mux-control is contended. */int mux_state_try_select_delay(struct mux_state *mstate, unsigned int delay_us){ return mux_control_try_select_delay(mstate->mux, mstate->state, delay_us);}EXPORT_SYMBOL_GPL(mux_state_try_select_delay); /** * mux_control_deselect() - Deselect the previously selected multiplexer state. * @mux: The mux-control to deselect. * * It is required that a single call is made to mux_control_deselect() for * each and every successful call made to either of mux_control_select() or * mux_control_try_select(). * * Return: 0 on success and a negative errno on error. An error can only * occur if the mux has an idle state. Note that even if an error occurs, the * mux-control is unlocked and is thus free for the next access. */int mux_control_deselect(struct mux_control *mux){ int ret = 0; if (mux->idle_state != MUX_IDLE_AS_IS && mux->idle_state != mux->cached_state) ret = mux_control_set(mux, mux->idle_state); up(&mux->lock); return ret;}EXPORT_SYMBOL_GPL(mux_control_deselect); Lines 1–500 of 910. Load more
// SPDX-License-Identifier: GPL-2.0 /* * Multiplexer subsystem * * Copyright (C) 2017 Axentia Technologies AB * * Author: Peter Rosin <peda@axentia.se> */ #define pr_fmt(fmt) "mux-core: " fmt #include <linux/delay.h> #include <linux/device.h> #include <linux/err.h> #include <linux/export.h> #include <linux/idr.h> #include <linux/init.h> #include <linux/module.h> #include <linux/mux/consumer.h> #include <linux/mux/driver.h> #include <linux/of.h> #include <linux/slab.h> /* * The idle-as-is "state" is not an actual state that may be selected, it * only implies that the state should not be changed. So, use that state * as indication that the cached state of the multiplexer is unknown. */ #define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS /** * struct mux_state - Represents a mux controller state specific to a given * consumer. * @mux: Pointer to a mux controller. * @state: State of the mux to be selected. * * This structure is specific to the consumer that acquires it and has * information specific to that consumer. */ struct mux_state { struct mux_control *mux; unsigned int state; }; static const struct class mux_class = { .name = "mux", }; /** * struct devm_mux_state_state - Tracks managed resources for mux-state objects. * @mstate: Pointer to a mux state. * @exit: An optional callback to execute before free. */ struct devm_mux_state_state { struct mux_state *mstate; int (*exit)(struct mux_state *mstate); }; static DEFINE_IDA(mux_ida); static int __init mux_init(void) { ida_init(&mux_ida); return class_register(&mux_class); } static void __exit mux_exit(void) { class_unregister(&mux_class); ida_destroy(&mux_ida); } static void mux_chip_release(struct device *dev) { struct mux_chip *mux_chip = to_mux_chip(dev); ida_free(&mux_ida, mux_chip->id); kfree(mux_chip); } static const struct device_type mux_type = { .name = "mux-chip", .release = mux_chip_release, }; /** * mux_chip_alloc() - Allocate a mux-chip. * @dev: The parent device implementing the mux interface. * @controllers: The number of mux controllers to allocate for this chip. * @sizeof_priv: Size of extra memory area for private use by the caller. * * After allocating the mux-chip with the desired number of mux controllers * but before registering the chip, the mux driver is required to configure * the number of valid mux states in the mux_chip->mux[N].states members and * the desired idle state in the returned mux_chip->mux[N].idle_state members. * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to * provide a pointer to the operations struct in the mux_chip->ops member * before registering the mux-chip with mux_chip_register. * * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. */ struct mux_chip *mux_chip_alloc(struct device *dev, unsigned int controllers, size_t sizeof_priv) { struct mux_chip *mux_chip; int i; if (WARN_ON(!dev || !controllers)) return ERR_PTR(-EINVAL); mux_chip = kzalloc(size_add(struct_size(mux_chip, mux, controllers), sizeof_priv), GFP_KERNEL); if (!mux_chip) return ERR_PTR(-ENOMEM); mux_chip->dev.class = &mux_class; mux_chip->dev.type = &mux_type; mux_chip->dev.parent = dev; mux_chip->dev.of_node = dev->of_node; dev_set_drvdata(&mux_chip->dev, mux_chip); mux_chip->id = ida_alloc(&mux_ida, GFP_KERNEL); if (mux_chip->id < 0) { int err = mux_chip->id; pr_err("muxchipX failed to get a device id\n"); kfree(mux_chip); return ERR_PTR(err); } dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id); mux_chip->controllers = controllers; for (i = 0; i < controllers; ++i) { struct mux_control *mux = &mux_chip->mux[i]; mux->chip = mux_chip; sema_init(&mux->lock, 1); mux->cached_state = MUX_CACHE_UNKNOWN; mux->idle_state = MUX_IDLE_AS_IS; mux->last_change = ktime_get(); } device_initialize(&mux_chip->dev); return mux_chip; } EXPORT_SYMBOL_GPL(mux_chip_alloc); static int mux_control_set(struct mux_control *mux, int state) { int ret = mux->chip->ops->set(mux, state); mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state; if (ret >= 0) mux->last_change = ktime_get(); return ret; } /** * mux_chip_register() - Register a mux-chip, thus readying the controllers * for use. * @mux_chip: The mux-chip to register. * * Do not retry registration of the same mux-chip on failure. You should * instead put it away with mux_chip_free() and allocate a new one, if you * for some reason would like to retry registration. * * Return: Zero on success or a negative errno on error. */ int mux_chip_register(struct mux_chip *mux_chip) { int i; int ret; for (i = 0; i < mux_chip->controllers; ++i) { struct mux_control *mux = &mux_chip->mux[i]; if (mux->idle_state == mux->cached_state) continue; ret = mux_control_set(mux, mux->idle_state); if (ret < 0) { dev_err(&mux_chip->dev, "unable to set idle state\n"); return ret; } } ret = device_add(&mux_chip->dev); if (ret < 0) dev_err(&mux_chip->dev, "device_add failed in %s: %d\n", __func__, ret); return ret; } EXPORT_SYMBOL_GPL(mux_chip_register); /** * mux_chip_unregister() - Take the mux-chip off-line. * @mux_chip: The mux-chip to unregister. * * mux_chip_unregister() reverses the effects of mux_chip_register(). * But not completely, you should not try to call mux_chip_register() * on a mux-chip that has been registered before. */ void mux_chip_unregister(struct mux_chip *mux_chip) { device_del(&mux_chip->dev); } EXPORT_SYMBOL_GPL(mux_chip_unregister); /** * mux_chip_free() - Free the mux-chip for good. * @mux_chip: The mux-chip to free. * * mux_chip_free() reverses the effects of mux_chip_alloc(). */ void mux_chip_free(struct mux_chip *mux_chip) { if (!mux_chip) return; put_device(&mux_chip->dev); } EXPORT_SYMBOL_GPL(mux_chip_free); static void devm_mux_chip_release(struct device *dev, void *res) { struct mux_chip *mux_chip = *(struct mux_chip **)res; mux_chip_free(mux_chip); } /** * devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc(). * @dev: The parent device implementing the mux interface. * @controllers: The number of mux controllers to allocate for this chip. * @sizeof_priv: Size of extra memory area for private use by the caller. * * See mux_chip_alloc() for more details. * * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno. */ struct mux_chip *devm_mux_chip_alloc(struct device *dev, unsigned int controllers, size_t sizeof_priv) { struct mux_chip **ptr, *mux_chip; ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv); if (IS_ERR(mux_chip)) { devres_free(ptr); return mux_chip; } *ptr = mux_chip; devres_add(dev, ptr); return mux_chip; } EXPORT_SYMBOL_GPL(devm_mux_chip_alloc); static void devm_mux_chip_reg_release(struct device *dev, void *res) { struct mux_chip *mux_chip = *(struct mux_chip **)res; mux_chip_unregister(mux_chip); } /** * devm_mux_chip_register() - Resource-managed version mux_chip_register(). * @dev: The parent device implementing the mux interface. * @mux_chip: The mux-chip to register. * * See mux_chip_register() for more details. * * Return: Zero on success or a negative errno on error. */ int devm_mux_chip_register(struct device *dev, struct mux_chip *mux_chip) { struct mux_chip **ptr; int res; ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return -ENOMEM; res = mux_chip_register(mux_chip); if (res) { devres_free(ptr); return res; } *ptr = mux_chip; devres_add(dev, ptr); return res; } EXPORT_SYMBOL_GPL(devm_mux_chip_register); /** * mux_control_states() - Query the number of multiplexer states. * @mux: The mux-control to query. * * Return: The number of multiplexer states. */ unsigned int mux_control_states(struct mux_control *mux) { return mux->states; } EXPORT_SYMBOL_GPL(mux_control_states); /* * The mux->lock must be down when calling this function. */ static int __mux_control_select(struct mux_control *mux, int state) { int ret; if (WARN_ON(state < 0 || state >= mux->states)) return -EINVAL; if (mux->cached_state == state) return 0; ret = mux_control_set(mux, state); if (ret >= 0) return 0; /* The mux update failed, try to revert if appropriate... */ if (mux->idle_state != MUX_IDLE_AS_IS) mux_control_set(mux, mux->idle_state); return ret; } static void mux_control_delay(struct mux_control *mux, unsigned int delay_us) { ktime_t delayend; s64 remaining; if (!delay_us) return; delayend = ktime_add_us(mux->last_change, delay_us); remaining = ktime_us_delta(delayend, ktime_get()); if (remaining > 0) fsleep(remaining); } /** * mux_control_select_delay() - Select the given multiplexer state. * @mux: The mux-control to request a change of state from. * @state: The new requested state. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-control state, it will be locked until * there is a call to mux_control_deselect(). If the mux-control is already * selected when mux_control_select() is called, the caller will be blocked * until mux_control_deselect() or mux_state_deselect() is called (by someone * else). * * Therefore, make sure to call mux_control_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_control_deselect() if mux_control_select() fails. * * Return: 0 when the mux-control state has the requested state or a negative * errno on error. */ int mux_control_select_delay(struct mux_control *mux, unsigned int state, unsigned int delay_us) { int ret; ret = down_killable(&mux->lock); if (ret < 0) return ret; ret = __mux_control_select(mux, state); if (ret >= 0) mux_control_delay(mux, delay_us); if (ret < 0) up(&mux->lock); return ret; } EXPORT_SYMBOL_GPL(mux_control_select_delay); /** * mux_state_select_delay() - Select the given multiplexer state. * @mstate: The mux-state to select. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-state, its mux-control will be locked * until there is a call to mux_state_deselect(). If the mux-control is already * selected when mux_state_select() is called, the caller will be blocked * until mux_state_deselect() or mux_control_deselect() is called (by someone * else). * * Therefore, make sure to call mux_state_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_state_deselect() if mux_state_select() fails. * * Return: 0 when the mux-state has been selected or a negative * errno on error. */ int mux_state_select_delay(struct mux_state *mstate, unsigned int delay_us) { return mux_control_select_delay(mstate->mux, mstate->state, delay_us); } EXPORT_SYMBOL_GPL(mux_state_select_delay); /** * mux_control_try_select_delay() - Try to select the given multiplexer state. * @mux: The mux-control to request a change of state from. * @state: The new requested state. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-control state, it will be locked until * mux_control_deselect() is called. * * Therefore, make sure to call mux_control_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_control_deselect() if mux_control_try_select() fails. * * Return: 0 when the mux-control state has the requested state or a negative * errno on error. Specifically -EBUSY if the mux-control is contended. */ int mux_control_try_select_delay(struct mux_control *mux, unsigned int state, unsigned int delay_us) { int ret; if (down_trylock(&mux->lock)) return -EBUSY; ret = __mux_control_select(mux, state); if (ret >= 0) mux_control_delay(mux, delay_us); if (ret < 0) up(&mux->lock); return ret; } EXPORT_SYMBOL_GPL(mux_control_try_select_delay); /** * mux_state_try_select_delay() - Try to select the given multiplexer state. * @mstate: The mux-state to select. * @delay_us: The time to delay (in microseconds) if the mux state is changed. * * On successfully selecting the mux-state, its mux-control will be locked * until mux_state_deselect() is called. * * Therefore, make sure to call mux_state_deselect() when the operation is * complete and the mux-control is free for others to use, but do not call * mux_state_deselect() if mux_state_try_select() fails. * * Return: 0 when the mux-state has been selected or a negative errno on * error. Specifically -EBUSY if the mux-control is contended. */ int mux_state_try_select_delay(struct mux_state *mstate, unsigned int delay_us) { return mux_control_try_select_delay(mstate->mux, mstate->state, delay_us); } EXPORT_SYMBOL_GPL(mux_state_try_select_delay); /** * mux_control_deselect() - Deselect the previously selected multiplexer state. * @mux: The mux-control to deselect. * * It is required that a single call is made to mux_control_deselect() for * each and every successful call made to either of mux_control_select() or * mux_control_try_select(). * * Return: 0 on success and a negative errno on error. An error can only * occur if the mux has an idle state. Note that even if an error occurs, the * mux-control is unlocked and is thus free for the next access. */ int mux_control_deselect(struct mux_control *mux) { int ret = 0; if (mux->idle_state != MUX_IDLE_AS_IS && mux->idle_state != mux->cached_state) ret = mux_control_set(mux, mux->idle_state); up(&mux->lock); return ret; } EXPORT_SYMBOL_GPL(mux_control_deselect);