Merge tag 'pwrseq-initial-for-v6.11' of...

Merge tag 'pwrseq-initial-for-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux into HEAD

Initial implementation of the power sequencing subsystem for linux v6.11

MAINTAINERS

@@ -17908,6 +17908,14 @@ F:	include/linux/pm_*
 F:	include/linux/powercap.h
 F:	kernel/configs/nopm.config
 
+POWER SEQUENCING
+M:	Bartosz Golaszewski <brgl@bgdev.pl>
+L:	linux-pm@vger.kernel.org
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git
+F:	drivers/power/sequencing/
+F:	include/linux/pwrseq/
+
 POWER STATE COORDINATION INTERFACE (PSCI)
 M:	Mark Rutland <mark.rutland@arm.com>
 M:	Lorenzo Pieralisi <lpieralisi@kernel.org>

drivers/power/Kconfig

 # SPDX-License-Identifier: GPL-2.0-only
 source "drivers/power/reset/Kconfig"
+source "drivers/power/sequencing/Kconfig"
 source "drivers/power/supply/Kconfig"

drivers/power/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_POWER_RESET)	+= reset/
+obj-$(CONFIG_POWER_SEQUENCING)	+= sequencing/
 obj-$(CONFIG_POWER_SUPPLY)	+= supply/

drivers/power/sequencing/Kconfig

+# SPDX-License-Identifier: GPL-2.0-only
+
+menuconfig POWER_SEQUENCING
+	tristate "Power Sequencing support"
+	help
+	  Say Y here to enable the Power Sequencing subsystem.
+
+	  This subsystem is designed to control power to devices that share
+	  complex resources and/or require specific power sequences to be run
+	  during power-up.
+
+	  If unsure, say no.
+
+if POWER_SEQUENCING
+
+config POWER_SEQUENCING_QCOM_WCN
+	tristate "Qualcomm WCN family PMU driver"
+	default m if ARCH_QCOM
+	help
+	  Say Y here to enable the power sequencing driver for Qualcomm
+	  WCN Bluetooth/WLAN chipsets.
+
+	  Typically, a package from the Qualcomm WCN family contains the BT
+	  and WLAN modules whose power is controlled by the PMU module. As the
+	  former two share the power-up sequence which is executed by the PMU,
+	  this driver is needed for correct power control or else we'd risk not
+	  respecting the required delays between enabling Bluetooth and WLAN.
+
+endif

drivers/power/sequencing/Makefile

+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_POWER_SEQUENCING)		+= pwrseq-core.o
+pwrseq-core-y				:= core.o
+
+obj-$(CONFIG_POWER_SEQUENCING_QCOM_WCN)	+= pwrseq-qcom-wcn.o

drivers/power/sequencing/core.c

+// 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/lockdep.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_get(struct pwrseq_unit *unit)
+{
+	kref_get(&unit->ref);
+
+	return unit;
+}
+
+static void pwrseq_unit_release(struct kref *ref);
+
+static void pwrseq_unit_put(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_put(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_put(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, *pos;
+
+	list_for_each_entry_safe(target, pos, &pwrseq->targets, list) {
+		list_del(&target->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_check_unit_deps(const struct pwrseq_unit_data *data,
+				  struct radix_tree_root *visited_units)
+{
+	const struct pwrseq_unit_data *tmp, **cur;
+	int ret;
+
+	ret = radix_tree_insert(visited_units, (unsigned long)data,
+				(void *)data);
+	if (ret)
+		return ret;
+
+	for (cur = data->deps; cur && *cur; cur++) {
+		tmp = radix_tree_lookup(visited_units, (unsigned long)*cur);
+		if (tmp) {
+			WARN(1, "Circular dependency in power sequencing flow detected!\n");
+			return -EINVAL;
+		}
+
+		ret = pwrseq_check_unit_deps(*cur, visited_units);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int pwrseq_check_target_deps(const struct pwrseq_target_data *data)
+{
+	struct radix_tree_root visited_units;
+	struct radix_tree_iter iter;
+	void __rcu **slot;
+	int ret;
+
+	if (!data->unit)
+		return -EINVAL;
+
+	INIT_RADIX_TREE(&visited_units, GFP_KERNEL);
+	ret = pwrseq_check_unit_deps(data->unit, &visited_units);
+	radix_tree_for_each_slot(slot, &visited_units, &iter, 0)
+		radix_tree_delete(&visited_units, iter.index);
+
+	return ret;
+}
+
+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);
+
+static struct pwrseq_unit *
+pwrseq_unit_setup(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)
+		return pwrseq_unit_get(unit);
+
+	unit = pwrseq_unit_new(data);
+	if (!unit)
+		return ERR_PTR(-ENOMEM);
+
+	if (data->deps) {
+		ret = pwrseq_unit_setup_deps(data->deps, &unit->deps,
+					     unit_list, processed_units);
+		if (ret) {
+			pwrseq_unit_put(unit);
+			return ERR_PTR(ret);
+		}
+	}
+
+	ret = radix_tree_insert(processed_units, (unsigned long)data, unit);
+	if (ret) {
+		pwrseq_unit_put(unit);
+		return ERR_PTR(ret);
+	}
+
+	list_add_tail(&unit->list, unit_list);
+
+	return unit;
+}
+
+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 i;
+
+	for (i = 0; data[i]; i++) {
+		pos = data[i];
+
+		unit = pwrseq_unit_setup(pos, unit_list, processed_units);
+		if (IS_ERR(unit))
+			return PTR_ERR(unit);
+
+		dep = pwrseq_unit_dep_new(unit);
+		if (!dep) {
+			pwrseq_unit_put(unit);
+			return -ENOMEM;
+		}
+
+		list_add_tail(&dep->list, dep_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];
+
+		ret = pwrseq_check_target_deps(pos);
+		if (ret)
+			return ret;
+
+		target = pwrseq_target_new(pos);
+		if (!target)
+			return -ENOMEM;
+
+		target->unit = pwrseq_unit_setup(pos->unit, &pwrseq->units,
+						 processed_units);
+		if (IS_ERR(target->unit)) {
+			ret = PTR_ERR(target->unit);
+			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, id;
+
+	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);
+
+	id = ida_alloc(&pwrseq_ida, GFP_KERNEL);
+	if (id < 0) {
+		kfree(pwrseq);
+		return ERR_PTR(id);
+	}
+
+	pwrseq->id = 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(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;
+
+	lockdep_assert_held_read(&pwrseq_sem);
+
+	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;
+
+	lockdep_assert_held_read(&pwrseq->rw_lock);
+	lockdep_assert_held(&pwrseq->state_lock);
+
+	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;
+
+	lockdep_assert_held_read(&pwrseq->rw_lock);
+	lockdep_assert_held(&pwrseq->state_lock);
+
+	if (unit->enable_count == 0) {
+		WARN(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");

drivers/power/sequencing/pwrseq-qcom-wcn.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Linaro Ltd.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/jiffies.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/pwrseq/provider.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+struct pwrseq_qcom_wcn_pdata {
+	const char *const *vregs;
+	size_t num_vregs;
+	unsigned int pwup_delay_ms;
+	unsigned int gpio_enable_delay_ms;
+};
+
+struct pwrseq_qcom_wcn_ctx {
+	struct pwrseq_device *pwrseq;
+	struct device_node *of_node;
+	const struct pwrseq_qcom_wcn_pdata *pdata;
+	struct regulator_bulk_data *regs;
+	struct gpio_desc *bt_gpio;
+	struct gpio_desc *wlan_gpio;
+	struct clk *clk;
+	unsigned long last_gpio_enable_jf;
+};
+
+static void pwrseq_qcom_wcn_ensure_gpio_delay(struct pwrseq_qcom_wcn_ctx *ctx)
+{
+	unsigned long diff_jiffies;
+	unsigned int diff_msecs;
+
+	if (!ctx->pdata->gpio_enable_delay_ms)
+		return;
+
+	diff_jiffies = jiffies - ctx->last_gpio_enable_jf;
+	diff_msecs = jiffies_to_msecs(diff_jiffies);
+
+	if (diff_msecs < ctx->pdata->gpio_enable_delay_ms)
+		msleep(ctx->pdata->gpio_enable_delay_ms - diff_msecs);
+}
+
+static int pwrseq_qcom_wcn_vregs_enable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	return regulator_bulk_enable(ctx->pdata->num_vregs, ctx->regs);
+}
+
+static int pwrseq_qcom_wcn_vregs_disable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	return regulator_bulk_disable(ctx->pdata->num_vregs, ctx->regs);
+}
+
+static const struct pwrseq_unit_data pwrseq_qcom_wcn_vregs_unit_data = {
+	.name = "regulators-enable",
+	.enable = pwrseq_qcom_wcn_vregs_enable,
+	.disable = pwrseq_qcom_wcn_vregs_disable,
+};
+
+static int pwrseq_qcom_wcn_clk_enable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	return clk_prepare_enable(ctx->clk);
+}
+
+static int pwrseq_qcom_wcn_clk_disable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	clk_disable_unprepare(ctx->clk);
+
+	return 0;
+}
+
+static const struct pwrseq_unit_data pwrseq_qcom_wcn_clk_unit_data = {
+	.name = "clock-enable",
+	.enable = pwrseq_qcom_wcn_clk_enable,
+	.disable = pwrseq_qcom_wcn_clk_disable,
+};
+
+static const struct pwrseq_unit_data *pwrseq_qcom_wcn_unit_deps[] = {
+	&pwrseq_qcom_wcn_vregs_unit_data,
+	&pwrseq_qcom_wcn_clk_unit_data,
+	NULL
+};
+
+static int pwrseq_qcom_wcn_bt_enable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	pwrseq_qcom_wcn_ensure_gpio_delay(ctx);
+	gpiod_set_value_cansleep(ctx->bt_gpio, 1);
+	ctx->last_gpio_enable_jf = jiffies;
+
+	return 0;
+}
+
+static int pwrseq_qcom_wcn_bt_disable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	gpiod_set_value_cansleep(ctx->bt_gpio, 0);
+
+	return 0;
+}
+
+static const struct pwrseq_unit_data pwrseq_qcom_wcn_bt_unit_data = {
+	.name = "bluetooth-enable",
+	.deps = pwrseq_qcom_wcn_unit_deps,
+	.enable = pwrseq_qcom_wcn_bt_enable,
+	.disable = pwrseq_qcom_wcn_bt_disable,
+};
+
+static int pwrseq_qcom_wcn_wlan_enable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	pwrseq_qcom_wcn_ensure_gpio_delay(ctx);
+	gpiod_set_value_cansleep(ctx->wlan_gpio, 1);
+	ctx->last_gpio_enable_jf = jiffies;
+
+	return 0;
+}
+
+static int pwrseq_qcom_wcn_wlan_disable(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	gpiod_set_value_cansleep(ctx->wlan_gpio, 0);
+
+	return 0;
+}
+
+static const struct pwrseq_unit_data pwrseq_qcom_wcn_wlan_unit_data = {
+	.name = "wlan-enable",
+	.deps = pwrseq_qcom_wcn_unit_deps,
+	.enable = pwrseq_qcom_wcn_wlan_enable,
+	.disable = pwrseq_qcom_wcn_wlan_disable,
+};
+
+static int pwrseq_qcom_wcn_pwup_delay(struct pwrseq_device *pwrseq)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+
+	if (ctx->pdata->pwup_delay_ms)
+		msleep(ctx->pdata->pwup_delay_ms);
+
+	return 0;
+}
+
+static const struct pwrseq_target_data pwrseq_qcom_wcn_bt_target_data = {
+	.name = "bluetooth",
+	.unit = &pwrseq_qcom_wcn_bt_unit_data,
+	.post_enable = pwrseq_qcom_wcn_pwup_delay,
+};
+
+static const struct pwrseq_target_data pwrseq_qcom_wcn_wlan_target_data = {
+	.name = "wlan",
+	.unit = &pwrseq_qcom_wcn_wlan_unit_data,
+	.post_enable = pwrseq_qcom_wcn_pwup_delay,
+};
+
+static const struct pwrseq_target_data *pwrseq_qcom_wcn_targets[] = {
+	&pwrseq_qcom_wcn_bt_target_data,
+	&pwrseq_qcom_wcn_wlan_target_data,
+	NULL
+};
+
+static const char *const pwrseq_qca6390_vregs[] = {
+	"vddio",
+	"vddaon",
+	"vddpmu",
+	"vddrfa0p95",
+	"vddrfa1p3",
+	"vddrfa1p9",
+	"vddpcie1p3",
+	"vddpcie1p9",
+};
+
+static const struct pwrseq_qcom_wcn_pdata pwrseq_qca6390_of_data = {
+	.vregs = pwrseq_qca6390_vregs,
+	.num_vregs = ARRAY_SIZE(pwrseq_qca6390_vregs),
+	.pwup_delay_ms = 60,
+	.gpio_enable_delay_ms = 100,
+};
+
+static const char *const pwrseq_wcn7850_vregs[] = {
+	"vdd",
+	"vddio",
+	"vddio1p2",
+	"vddaon",
+	"vdddig",
+	"vddrfa1p2",
+	"vddrfa1p8",
+};
+
+static const struct pwrseq_qcom_wcn_pdata pwrseq_wcn7850_of_data = {
+	.vregs = pwrseq_wcn7850_vregs,
+	.num_vregs = ARRAY_SIZE(pwrseq_wcn7850_vregs),
+	.pwup_delay_ms = 50,
+};
+
+static int pwrseq_qcom_wcn_match(struct pwrseq_device *pwrseq,
+				 struct device *dev)
+{
+	struct pwrseq_qcom_wcn_ctx *ctx = pwrseq_device_get_drvdata(pwrseq);
+	struct device_node *dev_node = dev->of_node;
+
+	/*
+	 * The PMU supplies power to the Bluetooth and WLAN modules. both
+	 * consume the PMU AON output so check the presence of the
+	 * 'vddaon-supply' property and whether it leads us to the right
+	 * device.
+	 */
+	if (!of_property_present(dev_node, "vddaon-supply"))
+		return 0;
+
+	struct device_node *reg_node __free(device_node) =
+			of_parse_phandle(dev_node, "vddaon-supply", 0);
+	if (!reg_node)
+		return 0;
+
+	/*
+	 * `reg_node` is the PMU AON regulator, its parent is the `regulators`
+	 * node and finally its grandparent is the PMU device node that we're
+	 * looking for.
+	 */
+	if (!reg_node->parent || !reg_node->parent->parent ||
+	    reg_node->parent->parent != ctx->of_node)
+		return 0;
+
+	return 1;
+}
+
+static int pwrseq_qcom_wcn_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pwrseq_qcom_wcn_ctx *ctx;
+	struct pwrseq_config config;
+	int i, ret;
+
+	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->of_node = dev->of_node;
+
+	ctx->pdata = of_device_get_match_data(dev);
+	if (!ctx->pdata)
+		return dev_err_probe(dev, -ENODEV,
+				     "Failed to obtain platform data\n");
+
+	ctx->regs = devm_kcalloc(dev, ctx->pdata->num_vregs,
+				 sizeof(*ctx->regs), GFP_KERNEL);
+	if (!ctx->regs)
+		return -ENOMEM;
+
+	for (i = 0; i < ctx->pdata->num_vregs; i++)
+		ctx->regs[i].supply = ctx->pdata->vregs[i];
+
+	ret = devm_regulator_bulk_get(dev, ctx->pdata->num_vregs, ctx->regs);
+	if (ret < 0)
+		return dev_err_probe(dev, ret,
+				     "Failed to get all regulators\n");
+
+	ctx->bt_gpio = devm_gpiod_get_optional(dev, "bt-enable", GPIOD_OUT_LOW);
+	if (IS_ERR(ctx->bt_gpio))
+		return dev_err_probe(dev, PTR_ERR(ctx->bt_gpio),
+				     "Failed to get the Bluetooth enable GPIO\n");
+
+	ctx->wlan_gpio = devm_gpiod_get_optional(dev, "wlan-enable",
+						 GPIOD_OUT_LOW);
+	if (IS_ERR(ctx->wlan_gpio))
+		return dev_err_probe(dev, PTR_ERR(ctx->wlan_gpio),
+				     "Failed to get the WLAN enable GPIO\n");
+
+	ctx->clk = devm_clk_get_optional(dev, NULL);
+	if (IS_ERR(ctx->clk))
+		return dev_err_probe(dev, PTR_ERR(ctx->clk),
+				     "Failed to get the reference clock\n");
+
+	memset(&config, 0, sizeof(config));
+
+	config.parent = dev;
+	config.owner = THIS_MODULE;
+	config.drvdata = ctx;
+	config.match = pwrseq_qcom_wcn_match;
+	config.targets = pwrseq_qcom_wcn_targets;
+
+	ctx->pwrseq = devm_pwrseq_device_register(dev, &config);
+	if (IS_ERR(ctx->pwrseq))
+		return dev_err_probe(dev, PTR_ERR(ctx->pwrseq),
+				     "Failed to register the power sequencer\n");
+
+	return 0;
+}
+
+static const struct of_device_id pwrseq_qcom_wcn_of_match[] = {
+	{
+		.compatible = "qcom,qca6390-pmu",
+		.data = &pwrseq_qca6390_of_data,
+	},
+	{
+		.compatible = "qcom,wcn7850-pmu",
+		.data = &pwrseq_wcn7850_of_data,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, pwrseq_qcom_wcn_of_match);
+
+static struct platform_driver pwrseq_qcom_wcn_driver = {
+	.driver = {
+		.name = "pwrseq-qcom_wcn",
+		.of_match_table = pwrseq_qcom_wcn_of_match,
+	},
+	.probe = pwrseq_qcom_wcn_probe,
+};
+module_platform_driver(pwrseq_qcom_wcn_driver);
+
+MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");
+MODULE_DESCRIPTION("Qualcomm WCN PMU power sequencing driver");
+MODULE_LICENSE("GPL");

include/linux/pwrseq/consumer.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Linaro Ltd.
+ */
+
+#ifndef __POWER_SEQUENCING_CONSUMER_H__
+#define __POWER_SEQUENCING_CONSUMER_H__
+
+#include <linux/err.h>
+
+struct device;
+struct pwrseq_desc;
+
+#if IS_ENABLED(CONFIG_POWER_SEQUENCING)
+
+struct pwrseq_desc * __must_check
+pwrseq_get(struct device *dev, const char *target);
+void pwrseq_put(struct pwrseq_desc *desc);
+
+struct pwrseq_desc * __must_check
+devm_pwrseq_get(struct device *dev, const char *target);
+
+int pwrseq_power_on(struct pwrseq_desc *desc);
+int pwrseq_power_off(struct pwrseq_desc *desc);
+
+#else /* CONFIG_POWER_SEQUENCING */
+
+static inline struct pwrseq_desc * __must_check
+pwrseq_get(struct device *dev, const char *target)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline void pwrseq_put(struct pwrseq_desc *desc)
+{
+}
+
+static inline struct pwrseq_desc * __must_check
+devm_pwrseq_get(struct device *dev, const char *target)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline int pwrseq_power_on(struct pwrseq_desc *desc)
+{
+	return -ENOSYS;
+}
+
+static inline int pwrseq_power_off(struct pwrseq_desc *desc)
+{
+	return -ENOSYS;
+}
+
+#endif /* CONFIG_POWER_SEQUENCING */
+
+#endif /* __POWER_SEQUENCING_CONSUMER_H__ */

include/linux/pwrseq/provider.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Linaro Ltd.
+ */
+
+#ifndef __POWER_SEQUENCING_PROVIDER_H__
+#define __POWER_SEQUENCING_PROVIDER_H__
+
+struct device;
+struct module;
+struct pwrseq_device;
+
+typedef int (*pwrseq_power_state_func)(struct pwrseq_device *);
+typedef int (*pwrseq_match_func)(struct pwrseq_device *, struct device *);
+
+/**
+ * struct pwrseq_unit_data - Configuration of a single power sequencing
+ *                           unit.
+ * @name: Name of the unit.
+ * @deps: Units that must be enabled before this one and disabled after it
+ *        in the order they come in this array. Must be NULL-terminated.
+ * @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.
+ */
+struct pwrseq_unit_data {
+	const char *name;
+	const struct pwrseq_unit_data **deps;
+	pwrseq_power_state_func enable;
+	pwrseq_power_state_func disable;
+};
+
+/**
+ * struct pwrseq_target_data - Configuration of a power sequencing target.
+ * @name: Name of the target.
+ * @unit: Final unit that this target must reach in order to be considered
+ *        enabled.
+ * @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_data {
+	const char *name;
+	const struct pwrseq_unit_data *unit;
+	pwrseq_power_state_func post_enable;
+};
+
+/**
+ * struct pwrseq_config - Configuration used for registering a new provider.
+ * @parent: Parent device for the sequencer. Must be set.
+ * @owner: Module providing this device.
+ * @drvdata: Private driver data.
+ * @match: Provider callback used to match the consumer device to the sequencer.
+ * @targets: Array of targets for this power sequencer. Must be NULL-terminated.
+ */
+struct pwrseq_config {
+	struct device *parent;
+	struct module *owner;
+	void *drvdata;
+	pwrseq_match_func match;
+	const struct pwrseq_target_data **targets;
+};
+
+struct pwrseq_device *
+pwrseq_device_register(const struct pwrseq_config *config);
+void pwrseq_device_unregister(struct pwrseq_device *pwrseq);
+struct pwrseq_device *
+devm_pwrseq_device_register(struct device *dev,
+			    const struct pwrseq_config *config);
+
+void *pwrseq_device_get_drvdata(struct pwrseq_device *pwrseq);
+
+#endif /* __POWER_SEQUENCING_PROVIDER_H__ */