diff options
Diffstat (limited to 'drivers/power/sequencing/core.c')
| -rw-r--r-- | drivers/power/sequencing/core.c | 1065 |
1 files changed, 1065 insertions, 0 deletions
diff --git a/drivers/power/sequencing/core.c b/drivers/power/sequencing/core.c new file mode 100644 index 000000000000..f5f3dc9d2407 --- /dev/null +++ b/drivers/power/sequencing/core.c @@ -0,0 +1,1065 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 Linaro Ltd. + */ + +#include <linux/bug.h> +#include <linux/cleanup.h> +#include <linux/debugfs.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/export.h> +#include <linux/idr.h> +#include <linux/kernel.h> +#include <linux/kref.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/property.h> +#include <linux/pwrseq/consumer.h> +#include <linux/pwrseq/provider.h> +#include <linux/radix-tree.h> +#include <linux/rwsem.h> +#include <linux/slab.h> + +/* + * Power-sequencing framework for linux. + * + * This subsystem allows power sequence providers to register a set of targets + * that consumers may request and power-up/down. + * + * Glossary: + * + * Unit - a unit is a discreet chunk of a power sequence. For instance one unit + * may enable a set of regulators, another may enable a specific GPIO. Units + * can define dependencies in the form of other units that must be enabled + * before it itself can be. + * + * Target - a target is a set of units (composed of the "final" unit and its + * dependencies) that a consumer selects by its name when requesting a handle + * to the power sequencer. Via the dependency system, multiple targets may + * share the same parts of a power sequence but ignore parts that are + * irrelevant. + * + * Descriptor - a handle passed by the pwrseq core to every consumer that + * serves as the entry point to the provider layer. It ensures coherence + * between different users and keeps reference counting consistent. + * + * Each provider must define a .match() callback whose role is to determine + * whether a potential consumer is in fact associated with this sequencer. + * This allows creating abstraction layers on top of regular device-tree + * resources like regulators, clocks and other nodes connected to the consumer + * via phandle. + */ + +static DEFINE_IDA(pwrseq_ida); + +/* + * Protects the device list on the pwrseq bus from concurrent modifications + * but allows simultaneous read-only access. + */ +static DECLARE_RWSEM(pwrseq_sem); + +/** + * struct pwrseq_unit - Private power-sequence unit data. + * @ref: Reference count for this object. When it goes to 0, the object is + * destroyed. + * @name: Name of this target. + * @list: Link to siblings on the list of all units of a single sequencer. + * @deps: List of units on which this unit depends. + * @enable: Callback running the part of the power-on sequence provided by + * this unit. + * @disable: Callback running the part of the power-off sequence provided + * by this unit. + * @enable_count: Current number of users that enabled this unit. May be the + * consumer of the power sequencer or other units that depend + * on this one. + */ +struct pwrseq_unit { + struct kref ref; + const char *name; + struct list_head list; + struct list_head deps; + pwrseq_power_state_func enable; + pwrseq_power_state_func disable; + unsigned int enable_count; +}; + +static struct pwrseq_unit *pwrseq_unit_new(const struct pwrseq_unit_data *data) +{ + struct pwrseq_unit *unit; + + unit = kzalloc(sizeof(*unit), GFP_KERNEL); + if (!unit) + return NULL; + + unit->name = kstrdup_const(data->name, GFP_KERNEL); + if (!unit->name) { + kfree(unit); + return NULL; + } + + kref_init(&unit->ref); + INIT_LIST_HEAD(&unit->deps); + unit->enable = data->enable; + unit->disable = data->disable; + + return unit; +} + +static struct pwrseq_unit *pwrseq_unit_incref(struct pwrseq_unit *unit) +{ + kref_get(&unit->ref); + + return unit; +} + +static void pwrseq_unit_release(struct kref *ref); + +static void pwrseq_unit_decref(struct pwrseq_unit *unit) +{ + kref_put(&unit->ref, pwrseq_unit_release); +} + +/** + * struct pwrseq_unit_dep - Wrapper around a reference to the unit structure + * allowing to keep it on multiple dependency lists + * in different units. + * @list: Siblings on the list. + * @unit: Address of the referenced unit. + */ +struct pwrseq_unit_dep { + struct list_head list; + struct pwrseq_unit *unit; +}; + +static struct pwrseq_unit_dep *pwrseq_unit_dep_new(struct pwrseq_unit *unit) +{ + struct pwrseq_unit_dep *dep; + + dep = kzalloc(sizeof(*dep), GFP_KERNEL); + if (!dep) + return NULL; + + dep->unit = unit; + + return dep; +} + +static void pwrseq_unit_dep_free(struct pwrseq_unit_dep *ref) +{ + pwrseq_unit_decref(ref->unit); + kfree(ref); +} + +static void pwrseq_unit_free_deps(struct list_head *list) +{ + struct pwrseq_unit_dep *dep, *next; + + list_for_each_entry_safe(dep, next, list, list) { + list_del(&dep->list); + pwrseq_unit_dep_free(dep); + } +} + +static void pwrseq_unit_release(struct kref *ref) +{ + struct pwrseq_unit *unit = container_of(ref, struct pwrseq_unit, ref); + + pwrseq_unit_free_deps(&unit->deps); + list_del(&unit->list); + kfree_const(unit->name); + kfree(unit); +} + +/** + * struct pwrseq_target - Private power-sequence target data. + * @list: Siblings on the list of all targets exposed by a power sequencer. + * @name: Name of the target. + * @unit: Final unit for this target. + * @post_enable: Callback run after the target unit has been enabled, *after* + * the state lock has been released. It's useful for implementing + * boot-up delays without blocking other users from powering up + * using the same power sequencer. + */ +struct pwrseq_target { + struct list_head list; + const char *name; + struct pwrseq_unit *unit; + pwrseq_power_state_func post_enable; +}; + +static struct pwrseq_target * +pwrseq_target_new(const struct pwrseq_target_data *data) +{ + struct pwrseq_target *target; + + target = kzalloc(sizeof(*target), GFP_KERNEL); + if (!target) + return NULL; + + target->name = kstrdup_const(data->name, GFP_KERNEL); + if (!target->name) { + kfree(target); + return NULL; + } + + target->post_enable = data->post_enable; + + return target; +} + +static void pwrseq_target_free(struct pwrseq_target *target) +{ + pwrseq_unit_decref(target->unit); + kfree_const(target->name); + kfree(target); +} + +/** + * struct pwrseq_device - Private power sequencing data. + * @dev: Device struct associated with this sequencer. + * @id: Device ID. + * @owner: Prevents removal of active power sequencing providers. + * @rw_lock: Protects the device from being unregistered while in use. + * @state_lock: Prevents multiple users running the power sequence at the same + * time. + * @match: Power sequencer matching callback. + * @targets: List of targets exposed by this sequencer. + * @units: List of all units supported by this sequencer. + */ +struct pwrseq_device { + struct device dev; + int id; + struct module *owner; + struct rw_semaphore rw_lock; + struct mutex state_lock; + pwrseq_match_func match; + struct list_head targets; + struct list_head units; +}; + +static struct pwrseq_device *to_pwrseq_device(struct device *dev) +{ + return container_of(dev, struct pwrseq_device, dev); +} + +static struct pwrseq_device *pwrseq_device_get(struct pwrseq_device *pwrseq) +{ + get_device(&pwrseq->dev); + + return pwrseq; +} + +static void pwrseq_device_put(struct pwrseq_device *pwrseq) +{ + put_device(&pwrseq->dev); +} + +/** + * struct pwrseq_desc - Wraps access to the pwrseq_device and ensures that one + * user cannot break the reference counting for others. + * @pwrseq: Reference to the power sequencing device. + * @target: Reference to the target this descriptor allows to control. + * @powered_on: Power state set by the holder of the descriptor (not necessarily + * corresponding to the actual power state of the device). + */ +struct pwrseq_desc { + struct pwrseq_device *pwrseq; + struct pwrseq_target *target; + bool powered_on; +}; + +static const struct bus_type pwrseq_bus = { + .name = "pwrseq", +}; + +static void pwrseq_release(struct device *dev) +{ + struct pwrseq_device *pwrseq = to_pwrseq_device(dev); + struct pwrseq_target *target; + + list_for_each_entry(target, &pwrseq->targets, list) + pwrseq_target_free(target); + + mutex_destroy(&pwrseq->state_lock); + ida_free(&pwrseq_ida, pwrseq->id); + kfree(pwrseq); +} + +static const struct device_type pwrseq_device_type = { + .name = "power_sequencer", + .release = pwrseq_release, +}; + +static int pwrseq_unit_setup_deps(const struct pwrseq_unit_data **data, + struct list_head *dep_list, + struct list_head *unit_list, + struct radix_tree_root *processed_units) +{ + const struct pwrseq_unit_data *pos; + struct pwrseq_unit_dep *dep; + struct pwrseq_unit *unit; + int ret, i; + + for (i = 0; data[i]; i++) { + pos = data[i]; + + unit = radix_tree_lookup(processed_units, (unsigned long)pos); + if (unit) { + pwrseq_unit_incref(unit); + } else { + unit = pwrseq_unit_new(pos); + if (!unit) + return -ENOMEM; + + if (pos->deps) { + ret = pwrseq_unit_setup_deps(pos->deps, + &unit->deps, + unit_list, + processed_units); + if (ret) { + pwrseq_unit_decref(unit); + return ret; + } + } + + ret = radix_tree_insert(processed_units, + (unsigned long)pos, unit); + if (ret) { + pwrseq_unit_decref(unit); + return ret; + } + + list_add_tail(&unit->list, unit_list); + } + + dep = pwrseq_unit_dep_new(unit); + if (!dep) { + pwrseq_unit_decref(unit); + return -ENOMEM; + } + + list_add_tail(&dep->list, dep_list); + } + + return 0; +} + +static int pwrseq_target_setup_unit(struct pwrseq_target *target, + const struct pwrseq_unit_data *data, + struct list_head *unit_list, + struct radix_tree_root *processed_units) +{ + struct pwrseq_unit *unit; + int ret; + + unit = radix_tree_lookup(processed_units, (unsigned long)data); + if (unit) { + target->unit = pwrseq_unit_incref(unit); + return 0; + } + + unit = pwrseq_unit_new(data); + if (!unit) + return -ENOMEM; + + ret = pwrseq_unit_setup_deps(data->deps, &unit->deps, unit_list, + processed_units); + if (ret) { + pwrseq_unit_decref(unit); + return ret; + } + + ret = radix_tree_insert(processed_units, (unsigned long)data, unit); + if (ret) { + pwrseq_unit_decref(unit); + return ret; + } + + target->unit = unit; + list_add_tail(&unit->list, unit_list); + + return 0; +} + +static int pwrseq_do_setup_targets(const struct pwrseq_target_data **data, + struct pwrseq_device *pwrseq, + struct radix_tree_root *processed_units) +{ + const struct pwrseq_target_data *pos; + struct pwrseq_target *target; + int ret, i; + + for (i = 0; data[i]; i++) { + pos = data[i]; + + target = pwrseq_target_new(pos); + if (!target) + return -ENOMEM; + + ret = pwrseq_target_setup_unit(target, pos->unit, + &pwrseq->units, + processed_units); + if (ret) { + pwrseq_target_free(target); + return ret; + } + + list_add_tail(&target->list, &pwrseq->targets); + } + + return 0; +} + +static int pwrseq_setup_targets(const struct pwrseq_target_data **targets, + struct pwrseq_device *pwrseq) +{ + struct radix_tree_root processed_units; + struct radix_tree_iter iter; + void __rcu **slot; + int ret; + + INIT_RADIX_TREE(&processed_units, GFP_KERNEL); + ret = pwrseq_do_setup_targets(targets, pwrseq, &processed_units); + radix_tree_for_each_slot(slot, &processed_units, &iter, 0) + radix_tree_delete(&processed_units, iter.index); + + return ret; +} + +/** + * pwrseq_device_register() - Register a new power sequencer. + * @config: Configuration of the new power sequencing device. + * + * The config structure is only used during the call and can be freed after + * the function returns. The config structure *must* have the parent device + * as well as the match() callback and at least one target set. + * + * Returns: + * Returns the address of the new pwrseq device or ERR_PTR() on failure. + */ +struct pwrseq_device * +pwrseq_device_register(const struct pwrseq_config *config) +{ + struct pwrseq_device *pwrseq; + int ret; + + if (!config->parent || !config->match || !config->targets || + !config->targets[0]) + return ERR_PTR(-EINVAL); + + pwrseq = kzalloc(sizeof(*pwrseq), GFP_KERNEL); + if (!pwrseq) + return ERR_PTR(-ENOMEM); + + pwrseq->dev.type = &pwrseq_device_type; + pwrseq->dev.bus = &pwrseq_bus; + pwrseq->dev.parent = config->parent; + device_set_node(&pwrseq->dev, dev_fwnode(config->parent)); + dev_set_drvdata(&pwrseq->dev, config->drvdata); + + pwrseq->id = ida_alloc(&pwrseq_ida, GFP_KERNEL); + if (pwrseq->id < 0) { + kfree(pwrseq); + return ERR_PTR(pwrseq->id); + } + + /* + * From this point onwards the device's release() callback is + * responsible for freeing resources. + */ + device_initialize(&pwrseq->dev); + + ret = dev_set_name(&pwrseq->dev, "pwrseq.%d", pwrseq->id); + if (ret) + goto err_put_pwrseq; + + pwrseq->owner = config->owner ?: THIS_MODULE; + pwrseq->match = config->match; + + init_rwsem(&pwrseq->rw_lock); + mutex_init(&pwrseq->state_lock); + INIT_LIST_HEAD(&pwrseq->targets); + INIT_LIST_HEAD(&pwrseq->units); + + ret = pwrseq_setup_targets(config->targets, pwrseq); + if (ret) + goto err_put_pwrseq; + + scoped_guard(rwsem_write, &pwrseq_sem) { + ret = device_add(&pwrseq->dev); + if (ret) + goto err_put_pwrseq; + } + + return pwrseq; + +err_put_pwrseq: + pwrseq_device_put(pwrseq); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(pwrseq_device_register); + +/** + * pwrseq_device_unregister() - Unregister the power sequencer. + * @pwrseq: Power sequencer to unregister. + */ +void pwrseq_device_unregister(struct pwrseq_device *pwrseq) +{ + struct device *dev = &pwrseq->dev; + struct pwrseq_target *target; + + scoped_guard(mutex, &pwrseq->state_lock) { + guard(rwsem_write)(&pwrseq->rw_lock); + + list_for_each_entry(target, &pwrseq->targets, list) + WARN_ONCE(target->unit->enable_count, + "REMOVING POWER SEQUENCER WITH ACTIVE USERS\n"); + + guard(rwsem_write)(&pwrseq_sem); + + device_del(dev); + } + + pwrseq_device_put(pwrseq); +} +EXPORT_SYMBOL_GPL(pwrseq_device_unregister); + +static void devm_pwrseq_device_unregister(void *data) +{ + struct pwrseq_device *pwrseq = data; + + pwrseq_device_unregister(pwrseq); +} + +/** + * devm_pwrseq_device_register() - Managed variant of pwrseq_device_register(). + * @dev: Managing device. + * @config: Configuration of the new power sequencing device. + * + * Returns: + * Returns the address of the new pwrseq device or ERR_PTR() on failure. + */ +struct pwrseq_device * +devm_pwrseq_device_register(struct device *dev, + const struct pwrseq_config *config) +{ + struct pwrseq_device *pwrseq; + int ret; + + pwrseq = pwrseq_device_register(config); + if (IS_ERR(pwrseq)) + return pwrseq; + + ret = devm_add_action_or_reset(dev, devm_pwrseq_device_unregister, + pwrseq); + if (ret) + return ERR_PTR(ret); + + return pwrseq; +} +EXPORT_SYMBOL_GPL(devm_pwrseq_device_register); + +/** + * pwrseq_device_get_drvdata() - Get the driver private data associated with + * this sequencer. + * @pwrseq: Power sequencer object. + * + * Returns: + * Address of the private driver data. + */ +void *pwrseq_device_get_drvdata(struct pwrseq_device *pwrseq) +{ + return dev_get_drvdata(&pwrseq->dev); +} +EXPORT_SYMBOL_GPL(pwrseq_device_get_drvdata); + +struct pwrseq_match_data { + struct pwrseq_desc *desc; + struct device *dev; + const char *target; +}; + +static int pwrseq_match_device(struct device *pwrseq_dev, void *data) +{ + struct pwrseq_device *pwrseq = to_pwrseq_device(pwrseq_dev); + struct pwrseq_match_data *match_data = data; + struct pwrseq_target *target; + int ret; + + guard(rwsem_read)(&pwrseq->rw_lock); + if (!device_is_registered(&pwrseq->dev)) + return 0; + + ret = pwrseq->match(pwrseq, match_data->dev); + if (ret <= 0) + return ret; + + /* We got the matching device, let's find the right target. */ + list_for_each_entry(target, &pwrseq->targets, list) { + if (strcmp(target->name, match_data->target)) + continue; + + match_data->desc->target = target; + } + + /* + * This device does not have this target. No point in deferring as it + * will not get a new target dynamically later. + */ + if (!match_data->desc->target) + return -ENOENT; + + if (!try_module_get(pwrseq->owner)) + return -EPROBE_DEFER; + + match_data->desc->pwrseq = pwrseq_device_get(pwrseq); + + return 1; +} + +/** + * pwrseq_get() - Get the power sequencer associated with this device. + * @dev: Device for which to get the sequencer. + * @target: Name of the target exposed by the sequencer this device wants to + * reach. + * + * Returns: + * New power sequencer descriptor for use by the consumer driver or ERR_PTR() + * on failure. + */ +struct pwrseq_desc *pwrseq_get(struct device *dev, const char *target) +{ + struct pwrseq_match_data match_data; + int ret; + + struct pwrseq_desc *desc __free(kfree) = kzalloc(sizeof(*desc), + GFP_KERNEL); + if (!desc) + return ERR_PTR(-ENOMEM); + + match_data.desc = desc; + match_data.dev = dev; + match_data.target = target; + + guard(rwsem_read)(&pwrseq_sem); + + ret = bus_for_each_dev(&pwrseq_bus, NULL, &match_data, + pwrseq_match_device); + if (ret < 0) + return ERR_PTR(ret); + if (ret == 0) + /* No device matched. */ + return ERR_PTR(-EPROBE_DEFER); + + return no_free_ptr(desc); +} +EXPORT_SYMBOL_GPL(pwrseq_get); + +/** + * pwrseq_put() - Release the power sequencer descriptor. + * @desc: Descriptor to release. + */ +void pwrseq_put(struct pwrseq_desc *desc) +{ + struct pwrseq_device *pwrseq; + + if (!desc) + return; + + pwrseq = desc->pwrseq; + + if (desc->powered_on) + pwrseq_power_off(desc); + + kfree(desc); + module_put(pwrseq->owner); + pwrseq_device_put(pwrseq); +} +EXPORT_SYMBOL_GPL(pwrseq_put); + +static void devm_pwrseq_put(void *data) +{ + struct pwrseq_desc *desc = data; + + pwrseq_put(desc); +} + +/** + * devm_pwrseq_get() - Managed variant of pwrseq_get(). + * @dev: Device for which to get the sequencer and which also manages its + * lifetime. + * @target: Name of the target exposed by the sequencer this device wants to + * reach. + * + * Returns: + * New power sequencer descriptor for use by the consumer driver or ERR_PTR() + * on failure. + */ +struct pwrseq_desc *devm_pwrseq_get(struct device *dev, const char *target) +{ + struct pwrseq_desc *desc; + int ret; + + desc = pwrseq_get(dev, target); + if (IS_ERR(desc)) + return desc; + + ret = devm_add_action_or_reset(dev, devm_pwrseq_put, desc); + if (ret) + return ERR_PTR(ret); + + return desc; +} +EXPORT_SYMBOL_GPL(devm_pwrseq_get); + +static int pwrseq_unit_enable(struct pwrseq_device *pwrseq, + struct pwrseq_unit *target); +static int pwrseq_unit_disable(struct pwrseq_device *pwrseq, + struct pwrseq_unit *target); + +static int pwrseq_unit_enable_deps(struct pwrseq_device *pwrseq, + struct list_head *list) +{ + struct pwrseq_unit_dep *pos; + int ret = 0; + + list_for_each_entry(pos, list, list) { + ret = pwrseq_unit_enable(pwrseq, pos->unit); + if (ret) { + list_for_each_entry_continue_reverse(pos, list, list) + pwrseq_unit_disable(pwrseq, pos->unit); + break; + } + } + + return ret; +} + +static int pwrseq_unit_disable_deps(struct pwrseq_device *pwrseq, + struct list_head *list) +{ + struct pwrseq_unit_dep *pos; + int ret = 0; + + list_for_each_entry_reverse(pos, list, list) { + ret = pwrseq_unit_disable(pwrseq, pos->unit); + if (ret) { + list_for_each_entry_continue(pos, list, list) + pwrseq_unit_enable(pwrseq, pos->unit); + break; + } + } + + return ret; +} + +static int pwrseq_unit_enable(struct pwrseq_device *pwrseq, + struct pwrseq_unit *unit) +{ + int ret; + + if (unit->enable_count != 0) { + unit->enable_count++; + return 0; + } + + ret = pwrseq_unit_enable_deps(pwrseq, &unit->deps); + if (ret) { + dev_err(&pwrseq->dev, + "Failed to enable dependencies before power-on for target '%s': %d\n", + unit->name, ret); + return ret; + } + + if (unit->enable) { + ret = unit->enable(pwrseq); + if (ret) { + dev_err(&pwrseq->dev, + "Failed to enable target '%s': %d\n", + unit->name, ret); + pwrseq_unit_disable_deps(pwrseq, &unit->deps); + return ret; + } + } + + unit->enable_count++; + + return 0; +} + +static int pwrseq_unit_disable(struct pwrseq_device *pwrseq, + struct pwrseq_unit *unit) +{ + int ret; + + if (unit->enable_count == 0) { + WARN_ONCE(1, "Unmatched power-off for target '%s'\n", + unit->name); + return -EBUSY; + } + + if (unit->enable_count != 1) { + unit->enable_count--; + return 0; + } + + if (unit->disable) { + ret = unit->disable(pwrseq); + if (ret) { + dev_err(&pwrseq->dev, + "Failed to disable target '%s': %d\n", + unit->name, ret); + return ret; + } + } + + ret = pwrseq_unit_disable_deps(pwrseq, &unit->deps); + if (ret) { + dev_err(&pwrseq->dev, + "Failed to disable dependencies after power-off for target '%s': %d\n", + unit->name, ret); + if (unit->enable) + unit->enable(pwrseq); + return ret; + } + + unit->enable_count--; + + return 0; +} + +/** + * pwrseq_power_on() - Issue a power-on request on behalf of the consumer + * device. + * @desc: Descriptor referencing the power sequencer. + * + * This function tells the power sequencer that the consumer wants to be + * powered-up. The sequencer may already have powered-up the device in which + * case the function returns 0. If the power-up sequence is already in + * progress, the function will block until it's done and return 0. If this is + * the first request, the device will be powered up. + * + * Returns: + * 0 on success, negative error number on failure. + */ +int pwrseq_power_on(struct pwrseq_desc *desc) +{ + struct pwrseq_device *pwrseq; + struct pwrseq_target *target; + struct pwrseq_unit *unit; + int ret; + + might_sleep(); + + if (!desc || desc->powered_on) + return 0; + + pwrseq = desc->pwrseq; + target = desc->target; + unit = target->unit; + + guard(rwsem_read)(&pwrseq->rw_lock); + if (!device_is_registered(&pwrseq->dev)) + return -ENODEV; + + scoped_guard(mutex, &pwrseq->state_lock) { + ret = pwrseq_unit_enable(pwrseq, unit); + if (!ret) + desc->powered_on = true; + } + + if (target->post_enable) { + ret = target->post_enable(pwrseq); + if (ret) { + pwrseq_unit_disable(pwrseq, unit); + desc->powered_on = false; + } + } + + return ret; +} +EXPORT_SYMBOL_GPL(pwrseq_power_on); + +/** + * pwrseq_power_off() - Issue a power-off request on behalf of the consumer + * device. + * @desc: Descriptor referencing the power sequencer. + * + * This undoes the effects of pwrseq_power_on(). It issues a power-off request + * on behalf of the consumer and when the last remaining user does so, the + * power-down sequence will be started. If one is in progress, the function + * will block until it's complete and then return. + * + * Returns: + * 0 on success, negative error number on failure. + */ +int pwrseq_power_off(struct pwrseq_desc *desc) +{ + struct pwrseq_device *pwrseq; + struct pwrseq_unit *unit; + int ret; + + might_sleep(); + + if (!desc || !desc->powered_on) + return 0; + + pwrseq = desc->pwrseq; + unit = desc->target->unit; + + guard(rwsem_read)(&pwrseq->rw_lock); + if (!device_is_registered(&pwrseq->dev)) + return -ENODEV; + + guard(mutex)(&pwrseq->state_lock); + + ret = pwrseq_unit_disable(pwrseq, unit); + if (!ret) + desc->powered_on = false; + + return ret; +} +EXPORT_SYMBOL_GPL(pwrseq_power_off); + +#if IS_ENABLED(CONFIG_DEBUG_FS) + +struct pwrseq_debugfs_count_ctx { + struct device *dev; + loff_t index; +}; + +static int pwrseq_debugfs_seq_count(struct device *dev, void *data) +{ + struct pwrseq_debugfs_count_ctx *ctx = data; + + ctx->dev = dev; + + return ctx->index-- ? 0 : 1; +} + +static void *pwrseq_debugfs_seq_start(struct seq_file *seq, loff_t *pos) +{ + struct pwrseq_debugfs_count_ctx ctx; + + ctx.dev = NULL; + ctx.index = *pos; + + /* + * We're holding the lock for the entire printout so no need to fiddle + * with device reference count. + */ + down_read(&pwrseq_sem); + + bus_for_each_dev(&pwrseq_bus, NULL, &ctx, pwrseq_debugfs_seq_count); + if (!ctx.index) + return NULL; + + return ctx.dev; +} + +static void *pwrseq_debugfs_seq_next(struct seq_file *seq, void *data, + loff_t *pos) +{ + struct device *curr = data; + + ++*pos; + + struct device *next __free(put_device) = + bus_find_next_device(&pwrseq_bus, curr); + return next; +} + +static void pwrseq_debugfs_seq_show_target(struct seq_file *seq, + struct pwrseq_target *target) +{ + seq_printf(seq, " target: [%s] (target unit: [%s])\n", + target->name, target->unit->name); +} + +static void pwrseq_debugfs_seq_show_unit(struct seq_file *seq, + struct pwrseq_unit *unit) +{ + struct pwrseq_unit_dep *ref; + + seq_printf(seq, " unit: [%s] - enable count: %u\n", + unit->name, unit->enable_count); + + if (list_empty(&unit->deps)) + return; + + seq_puts(seq, " dependencies:\n"); + list_for_each_entry(ref, &unit->deps, list) + seq_printf(seq, " [%s]\n", ref->unit->name); +} + +static int pwrseq_debugfs_seq_show(struct seq_file *seq, void *data) +{ + struct device *dev = data; + struct pwrseq_device *pwrseq = to_pwrseq_device(dev); + struct pwrseq_target *target; + struct pwrseq_unit *unit; + + seq_printf(seq, "%s:\n", dev_name(dev)); + + seq_puts(seq, " targets:\n"); + list_for_each_entry(target, &pwrseq->targets, list) + pwrseq_debugfs_seq_show_target(seq, target); + + seq_puts(seq, " units:\n"); + list_for_each_entry(unit, &pwrseq->units, list) + pwrseq_debugfs_seq_show_unit(seq, unit); + + return 0; +} + +static void pwrseq_debugfs_seq_stop(struct seq_file *seq, void *data) +{ + up_read(&pwrseq_sem); +} + +static const struct seq_operations pwrseq_debugfs_sops = { + .start = pwrseq_debugfs_seq_start, + .next = pwrseq_debugfs_seq_next, + .show = pwrseq_debugfs_seq_show, + .stop = pwrseq_debugfs_seq_stop, +}; +DEFINE_SEQ_ATTRIBUTE(pwrseq_debugfs); + +static struct dentry *pwrseq_debugfs_dentry; + +#endif /* CONFIG_DEBUG_FS */ + +static int __init pwrseq_init(void) +{ + int ret; + + ret = bus_register(&pwrseq_bus); + if (ret) { + pr_err("Failed to register the power sequencer bus\n"); + return ret; + } + +#if IS_ENABLED(CONFIG_DEBUG_FS) + pwrseq_debugfs_dentry = debugfs_create_file("pwrseq", 0444, NULL, NULL, + &pwrseq_debugfs_fops); +#endif /* CONFIG_DEBUG_FS */ + + return 0; +} +subsys_initcall(pwrseq_init); + +static void __exit pwrseq_exit(void) +{ +#if IS_ENABLED(CONFIG_DEBUG_FS) + debugfs_remove_recursive(pwrseq_debugfs_dentry); +#endif /* CONFIG_DEBUG_FS */ + + bus_unregister(&pwrseq_bus); +} +module_exit(pwrseq_exit); + +MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>"); +MODULE_DESCRIPTION("Power Sequencing subsystem core"); +MODULE_LICENSE("GPL"); |