PM / Domains: Support for generic I/O PM domains (v8)

Introduce common headers, helper functions and callbacks allowing
platforms to use simple generic power domains for runtime power
management.

Introduce struct generic_pm_domain to be used for representing
power domains that each contain a number of devices and may be
parent domains or subdomains with respect to other power domains.
Among other things, this structure includes callbacks to be
provided by platforms for performing specific tasks related to
power management (i.e. ->stop_device() may disable a device's
clocks, while ->start_device() may enable them, ->power_off() is
supposed to remove power from the entire power domain
and ->power_on() is supposed to restore it).

Introduce functions that can be used as power domain runtime PM
callbacks, pm_genpd_runtime_suspend() and pm_genpd_runtime_resume(),
as well as helper functions for the initialization of a power
domain represented by a struct generic_power_domain object,
adding a device to or removing a device from it and adding or
removing subdomains.

Introduce configuration option CONFIG_PM_GENERIC_DOMAINS to be
selected by the platforms that want to use the new code.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Reviewed-by: Kevin Hilman <khilman@ti.com>

4 files changed, 577 insertions, 0 deletions

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 3647e114d0e7..2639ae79a372 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o
 obj-$(CONFIG_PM_RUNTIME)	+= runtime.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_PM_OPP)	+= opp.o
+obj-$(CONFIG_PM_GENERIC_DOMAINS)	+=  domain.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
\ No newline at end of file
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
new file mode 100644
index 000000000000..fd31be3be404
--- /dev/null
+++ b/drivers/base/power/domain.c
@@ -0,0 +1,494 @@
+/*
+ * drivers/base/power/domain.c - Common code related to device power domains.
+ *
+ * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_domain.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+
+#ifdef CONFIG_PM_RUNTIME
+
+static void genpd_sd_counter_dec(struct generic_pm_domain *genpd)
+{
+	if (!WARN_ON(genpd->sd_count == 0))
+			genpd->sd_count--;
+}
+
+/**
+ * __pm_genpd_save_device - Save the pre-suspend state of a device.
+ * @dle: Device list entry of the device to save the state of.
+ * @genpd: PM domain the device belongs to.
+ */
+static int __pm_genpd_save_device(struct dev_list_entry *dle,
+				  struct generic_pm_domain *genpd)
+{
+	struct device *dev = dle->dev;
+	struct device_driver *drv = dev->driver;
+	int ret = 0;
+
+	if (dle->need_restore)
+		return 0;
+
+	if (drv && drv->pm && drv->pm->runtime_suspend) {
+		if (genpd->start_device)
+			genpd->start_device(dev);
+
+		ret = drv->pm->runtime_suspend(dev);
+
+		if (genpd->stop_device)
+			genpd->stop_device(dev);
+	}
+
+	if (!ret)
+		dle->need_restore = true;
+
+	return ret;
+}
+
+/**
+ * __pm_genpd_restore_device - Restore the pre-suspend state of a device.
+ * @dle: Device list entry of the device to restore the state of.
+ * @genpd: PM domain the device belongs to.
+ */
+static void __pm_genpd_restore_device(struct dev_list_entry *dle,
+				      struct generic_pm_domain *genpd)
+{
+	struct device *dev = dle->dev;
+	struct device_driver *drv = dev->driver;
+
+	if (!dle->need_restore)
+		return;
+
+	if (drv && drv->pm && drv->pm->runtime_resume) {
+		if (genpd->start_device)
+			genpd->start_device(dev);
+
+		drv->pm->runtime_resume(dev);
+
+		if (genpd->stop_device)
+			genpd->stop_device(dev);
+	}
+
+	dle->need_restore = false;
+}
+
+/**
+ * pm_genpd_poweroff - Remove power from a given PM domain.
+ * @genpd: PM domain to power down.
+ *
+ * If all of the @genpd's devices have been suspended and all of its subdomains
+ * have been powered down, run the runtime suspend callbacks provided by all of
+ * the @genpd's devices' drivers and remove power from @genpd.
+ */
+static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
+{
+	struct generic_pm_domain *parent;
+	struct dev_list_entry *dle;
+	unsigned int not_suspended;
+	int ret;
+
+	if (genpd->power_is_off)
+		return 0;
+
+	if (genpd->sd_count > 0)
+		return -EBUSY;
+
+	not_suspended = 0;
+	list_for_each_entry(dle, &genpd->dev_list, node)
+		if (dle->dev->driver && !pm_runtime_suspended(dle->dev))
+			not_suspended++;
+
+	if (not_suspended > genpd->in_progress)
+		return -EBUSY;
+
+	if (genpd->gov && genpd->gov->power_down_ok) {
+		if (!genpd->gov->power_down_ok(&genpd->domain))
+			return -EAGAIN;
+	}
+
+	list_for_each_entry_reverse(dle, &genpd->dev_list, node) {
+		ret = __pm_genpd_save_device(dle, genpd);
+		if (ret)
+			goto err_dev;
+	}
+
+	if (genpd->power_off)
+		genpd->power_off(genpd);
+
+	genpd->power_is_off = true;
+
+	parent = genpd->parent;
+	if (parent) {
+		genpd_sd_counter_dec(parent);
+		if (parent->sd_count == 0)
+			queue_work(pm_wq, &parent->power_off_work);
+	}
+
+	return 0;
+
+ err_dev:
+	list_for_each_entry_continue(dle, &genpd->dev_list, node)
+		__pm_genpd_restore_device(dle, genpd);
+
+	return ret;
+}
+
+/**
+ * genpd_power_off_work_fn - Power off PM domain whose subdomain count is 0.
+ * @work: Work structure used for scheduling the execution of this function.
+ */
+static void genpd_power_off_work_fn(struct work_struct *work)
+{
+	struct generic_pm_domain *genpd;
+
+	genpd = container_of(work, struct generic_pm_domain, power_off_work);
+
+	if (genpd->parent)
+		mutex_lock(&genpd->parent->lock);
+	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+	pm_genpd_poweroff(genpd);
+	mutex_unlock(&genpd->lock);
+	if (genpd->parent)
+		mutex_unlock(&genpd->parent->lock);
+}
+
+/**
+ * pm_genpd_runtime_suspend - Suspend a device belonging to I/O PM domain.
+ * @dev: Device to suspend.
+ *
+ * Carry out a runtime suspend of a device under the assumption that its
+ * pm_domain field points to the domain member of an object of type
+ * struct generic_pm_domain representing a PM domain consisting of I/O devices.
+ */
+static int pm_genpd_runtime_suspend(struct device *dev)
+{
+	struct generic_pm_domain *genpd;
+
+	dev_dbg(dev, "%s()\n", __func__);
+
+	if (IS_ERR_OR_NULL(dev->pm_domain))
+		return -EINVAL;
+
+	genpd = container_of(dev->pm_domain, struct generic_pm_domain, domain);
+
+	if (genpd->parent)
+		mutex_lock(&genpd->parent->lock);
+	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+
+	if (genpd->stop_device) {
+		int ret = genpd->stop_device(dev);
+		if (ret)
+			goto out;
+	}
+	genpd->in_progress++;
+	pm_genpd_poweroff(genpd);
+	genpd->in_progress--;
+
+ out:
+	mutex_unlock(&genpd->lock);
+	if (genpd->parent)
+		mutex_unlock(&genpd->parent->lock);
+
+	return 0;
+}
+
+/**
+ * pm_genpd_poweron - Restore power to a given PM domain and its parents.
+ * @genpd: PM domain to power up.
+ *
+ * Restore power to @genpd and all of its parents so that it is possible to
+ * resume a device belonging to it.
+ */
+static int pm_genpd_poweron(struct generic_pm_domain *genpd)
+{
+	int ret = 0;
+
+ start:
+	if (genpd->parent)
+		mutex_lock(&genpd->parent->lock);
+	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+
+	if (!genpd->power_is_off)
+		goto out;
+
+	if (genpd->parent && genpd->parent->power_is_off) {
+		mutex_unlock(&genpd->lock);
+		mutex_unlock(&genpd->parent->lock);
+
+		ret = pm_genpd_poweron(genpd->parent);
+		if (ret)
+			return ret;
+
+		goto start;
+	}
+
+	if (genpd->power_on) {
+		int ret = genpd->power_on(genpd);
+		if (ret)
+			goto out;
+	}
+
+	genpd->power_is_off = false;
+	if (genpd->parent)
+		genpd->parent->sd_count++;
+
+ out:
+	mutex_unlock(&genpd->lock);
+	if (genpd->parent)
+		mutex_unlock(&genpd->parent->lock);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_runtime_resume - Resume a device belonging to I/O PM domain.
+ * @dev: Device to resume.
+ *
+ * Carry out a runtime resume of a device under the assumption that its
+ * pm_domain field points to the domain member of an object of type
+ * struct generic_pm_domain representing a PM domain consisting of I/O devices.
+ */
+static int pm_genpd_runtime_resume(struct device *dev)
+{
+	struct generic_pm_domain *genpd;
+	struct dev_list_entry *dle;
+	int ret;
+
+	dev_dbg(dev, "%s()\n", __func__);
+
+	if (IS_ERR_OR_NULL(dev->pm_domain))
+		return -EINVAL;
+
+	genpd = container_of(dev->pm_domain, struct generic_pm_domain, domain);
+
+	ret = pm_genpd_poweron(genpd);
+	if (ret)
+		return ret;
+
+	mutex_lock(&genpd->lock);
+
+	list_for_each_entry(dle, &genpd->dev_list, node) {
+		if (dle->dev == dev) {
+			__pm_genpd_restore_device(dle, genpd);
+			break;
+		}
+	}
+
+	if (genpd->start_device)
+		genpd->start_device(dev);
+
+	mutex_unlock(&genpd->lock);
+
+	return 0;
+}
+
+#else
+
+static inline void genpd_power_off_work_fn(struct work_struct *work) {}
+
+#define pm_genpd_runtime_suspend	NULL
+#define pm_genpd_runtime_resume		NULL
+
+#endif /* CONFIG_PM_RUNTIME */
+
+/**
+ * pm_genpd_add_device - Add a device to an I/O PM domain.
+ * @genpd: PM domain to add the device to.
+ * @dev: Device to be added.
+ */
+int pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
+{
+	struct dev_list_entry *dle;
+	int ret = 0;
+
+	dev_dbg(dev, "%s()\n", __func__);
+
+	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
+		return -EINVAL;
+
+	mutex_lock(&genpd->lock);
+
+	if (genpd->power_is_off) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	list_for_each_entry(dle, &genpd->dev_list, node)
+		if (dle->dev == dev) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+	dle = kzalloc(sizeof(*dle), GFP_KERNEL);
+	if (!dle) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dle->dev = dev;
+	dle->need_restore = false;
+	list_add_tail(&dle->node, &genpd->dev_list);
+
+	spin_lock_irq(&dev->power.lock);
+	dev->pm_domain = &genpd->domain;
+	spin_unlock_irq(&dev->power.lock);
+
+ out:
+	mutex_unlock(&genpd->lock);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_remove_device - Remove a device from an I/O PM domain.
+ * @genpd: PM domain to remove the device from.
+ * @dev: Device to be removed.
+ */
+int pm_genpd_remove_device(struct generic_pm_domain *genpd,
+			   struct device *dev)
+{
+	struct dev_list_entry *dle;
+	int ret = -EINVAL;
+
+	dev_dbg(dev, "%s()\n", __func__);
+
+	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
+		return -EINVAL;
+
+	mutex_lock(&genpd->lock);
+
+	list_for_each_entry(dle, &genpd->dev_list, node) {
+		if (dle->dev != dev)
+			continue;
+
+		spin_lock_irq(&dev->power.lock);
+		dev->pm_domain = NULL;
+		spin_unlock_irq(&dev->power.lock);
+
+		list_del(&dle->node);
+		kfree(dle);
+
+		ret = 0;
+		break;
+	}
+
+	mutex_unlock(&genpd->lock);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
+ * @genpd: Master PM domain to add the subdomain to.
+ * @new_subdomain: Subdomain to be added.
+ */
+int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
+			   struct generic_pm_domain *new_subdomain)
+{
+	struct generic_pm_domain *subdomain;
+	int ret = 0;
+
+	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(new_subdomain))
+		return -EINVAL;
+
+	mutex_lock(&genpd->lock);
+
+	if (genpd->power_is_off && !new_subdomain->power_is_off) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	list_for_each_entry(subdomain, &genpd->sd_list, sd_node) {
+		if (subdomain == new_subdomain) {
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	mutex_lock_nested(&new_subdomain->lock, SINGLE_DEPTH_NESTING);
+
+	list_add_tail(&new_subdomain->sd_node, &genpd->sd_list);
+	new_subdomain->parent = genpd;
+	if (!subdomain->power_is_off)
+		genpd->sd_count++;
+
+	mutex_unlock(&new_subdomain->lock);
+
+ out:
+	mutex_unlock(&genpd->lock);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
+ * @genpd: Master PM domain to remove the subdomain from.
+ * @target: Subdomain to be removed.
+ */
+int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
+			      struct generic_pm_domain *target)
+{
+	struct generic_pm_domain *subdomain;
+	int ret = -EINVAL;
+
+	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(target))
+		return -EINVAL;
+
+	mutex_lock(&genpd->lock);
+
+	list_for_each_entry(subdomain, &genpd->sd_list, sd_node) {
+		if (subdomain != target)
+			continue;
+
+		mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING);
+
+		list_del(&subdomain->sd_node);
+		subdomain->parent = NULL;
+		if (!subdomain->power_is_off)
+			genpd_sd_counter_dec(genpd);
+
+		mutex_unlock(&subdomain->lock);
+
+		ret = 0;
+		break;
+	}
+
+	mutex_unlock(&genpd->lock);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_init - Initialize a generic I/O PM domain object.
+ * @genpd: PM domain object to initialize.
+ * @gov: PM domain governor to associate with the domain (may be NULL).
+ * @is_off: Initial value of the domain's power_is_off field.
+ */
+void pm_genpd_init(struct generic_pm_domain *genpd,
+		   struct dev_power_governor *gov, bool is_off)
+{
+	if (IS_ERR_OR_NULL(genpd))
+		return;
+
+	INIT_LIST_HEAD(&genpd->sd_node);
+	genpd->parent = NULL;
+	INIT_LIST_HEAD(&genpd->dev_list);
+	INIT_LIST_HEAD(&genpd->sd_list);
+	mutex_init(&genpd->lock);
+	genpd->gov = gov;
+	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
+	genpd->in_progress = 0;
+	genpd->sd_count = 0;
+	genpd->power_is_off = is_off;
+	genpd->domain.ops.runtime_suspend = pm_genpd_runtime_suspend;
+	genpd->domain.ops.runtime_resume = pm_genpd_runtime_resume;
+	genpd->domain.ops.runtime_idle = pm_generic_runtime_idle;
+}
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
new file mode 100644
index 000000000000..b1a22c65380b
--- /dev/null
+++ b/include/linux/pm_domain.h
@@ -0,0 +1,78 @@
+/*
+ * pm_domain.h - Definitions and headers related to device power domains.
+ *
+ * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef _LINUX_PM_DOMAIN_H
+#define _LINUX_PM_DOMAIN_H
+
+#include <linux/device.h>
+
+struct dev_power_governor {
+	bool (*power_down_ok)(struct dev_pm_domain *domain);
+};
+
+struct generic_pm_domain {
+	struct dev_pm_domain domain;	/* PM domain operations */
+	struct list_head sd_node;	/* Node in the parent's subdomain list */
+	struct generic_pm_domain *parent;	/* Parent PM domain */
+	struct list_head sd_list;	/* List of dubdomains */
+	struct list_head dev_list;	/* List of devices */
+	struct mutex lock;
+	struct dev_power_governor *gov;
+	struct work_struct power_off_work;
+	unsigned int in_progress;	/* Number of devices being suspended now */
+	unsigned int sd_count;	/* Number of subdomains with power "on" */
+	bool power_is_off;	/* Whether or not power has been removed */
+	int (*power_off)(struct generic_pm_domain *domain);
+	int (*power_on)(struct generic_pm_domain *domain);
+	int (*start_device)(struct device *dev);
+	int (*stop_device)(struct device *dev);
+};
+
+struct dev_list_entry {
+	struct list_head node;
+	struct device *dev;
+	bool need_restore;
+};
+
+#ifdef CONFIG_PM_GENERIC_DOMAINS
+extern int pm_genpd_add_device(struct generic_pm_domain *genpd,
+			       struct device *dev);
+extern int pm_genpd_remove_device(struct generic_pm_domain *genpd,
+				  struct device *dev);
+extern int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
+				  struct generic_pm_domain *new_subdomain);
+extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
+				     struct generic_pm_domain *target);
+extern void pm_genpd_init(struct generic_pm_domain *genpd,
+			  struct dev_power_governor *gov, bool is_off);
+#else
+static inline int pm_genpd_add_device(struct generic_pm_domain *genpd,
+				      struct device *dev)
+{
+	return -ENOSYS;
+}
+static inline int pm_genpd_remove_device(struct generic_pm_domain *genpd,
+					 struct device *dev)
+{
+	return -ENOSYS;
+}
+static inline int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
+					 struct generic_pm_domain *new_sd)
+{
+	return -ENOSYS;
+}
+static inline int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
+					    struct generic_pm_domain *target)
+{
+	return -ENOSYS;
+}
+static inline void pm_genpd_init(struct generic_pm_domain *genpd,
+				 struct dev_power_governor *gov, bool is_off) {}
+#endif
+
+#endif /* _LINUX_PM_DOMAIN_H */
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 87f4d24b55b0..e83ac2556c86 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -227,3 +227,7 @@ config PM_OPP
 config PM_RUNTIME_CLK
 	def_bool y
 	depends on PM_RUNTIME && HAVE_CLK
+
+config PM_GENERIC_DOMAINS
+	bool
+	depends on PM