[RFC v2 02/12] PM / Domains: Support IRQ safe PM domains

diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index 8ba6625..c06f0b6 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt

@@ -607,7 +607,16 @@ individually.  Instead, a set of devices sharing a power resource can be put
 into a low-power state together at the same time by turning off the shared
 power resource.  Of course, they also need to be put into the full-power state
 together, by turning the shared power resource on.  A set of devices with this
-property is often referred to as a power domain.
+property is often referred to as a power domain. A power domain may also be
+nested inside another power domain.
+
+Devices, by default, operate in process context and if a device can operate in
+IRQ safe context, has to be explicitly set as IRQ safe. Power domains by

+subdomain to another IRQ safe domain.
 
 Support for power domains is provided through the pm_domain field of struct
 device.  This field is a pointer to an object of type struct dev_pm_domain,

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 8204615..3c4f675 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c

@@ -75,11 +75,59 @@ static struct genpd_lock_fns irq_lock = {
 	.unlock = genpd_unlock_irq,
 };
 
+static void genpd_lock_nosleep(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+}
+
+static void genpd_lock_nosleep_nested(struct generic_pm_domain *genpd,
+					int depth)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&genpd->slock, flags, depth);
+	genpd->lock_flags = flags;
+}
+
+static int genpd_lock_nosleep_interruptible(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+	return 0;

+	.lock = genpd_lock_nosleep,
+	.lock_nested = genpd_lock_nosleep_nested,
+	.lock_interruptible = genpd_lock_nosleep_interruptible,
+	.unlock = genpd_unlock_nosleep,
+};
+
 #define genpd_lock(p)			p->lock_fns->lock(p)
 #define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
 #define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
 #define genpd_unlock(p)			p->lock_fns->unlock(p)
 
+static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
+		struct generic_pm_domain *genpd)
+{
+	return dev->power.irq_safe && !genpd->irq_safe;
+}
+
 /*
  * Get the generic PM domain for a particular struct device.
  * This validates the struct device pointer, the PM domain pointer,

@@ -510,8 +570,11 @@ static int pm_genpd_runtime_resume(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	/* If power.irq_safe, the PM domain is never powered off. */
-	if (dev->power.irq_safe) {
+	/*
+	 * As we dont power off a non IRQ safe domain, which holds

+	 */
+	if (dev->power.irq_safe && !genpd->irq_safe) {
 		timed = false;
 		goto out;
 	}

@@ -1296,6 +1359,13 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
 		return -EINVAL;
 
+	if (genpd->irq_safe && !dev->power.irq_safe) {
+		dev_err(dev,
+			"PM Domain %s is IRQ safe; device has to IRQ safe.\n",

+			genpd->name);
+		return -EINVAL;
+	}
+
 	gpd_data = genpd_alloc_dev_data(dev, genpd, td);
 	if (IS_ERR(gpd_data))
 		return PTR_ERR(gpd_data);

@@ -1394,6 +1464,17 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 	    || genpd == subdomain)
 		return -EINVAL;
 
+	/*
+	 * If the domain can be powered on/off in an IRQ safe
+	 * context, ensure that the subdomain can also be
+	 * powered on/off in that context.
+	 */
+	if (!genpd->irq_safe && subdomain->irq_safe) {
+		WARN("Parent %s of subdomain %s must be IRQ-safe\n",