PM / QoS: Make it possible to expose PM QoS device flags to user space

Define two device PM QoS flags, PM_QOS_FLAG_NO_POWER_OFF
and PM_QOS_FLAG_REMOTE_WAKEUP, and introduce routines
dev_pm_qos_expose_flags() and dev_pm_qos_hide_flags() allowing the
caller to expose those two flags to user space or to hide them
from it, respectively.

After the flags have been exposed, user space will see two
additional sysfs attributes, pm_qos_no_power_off and
pm_qos_remote_wakeup, under the device's /sys/devices/.../power/
directory.  Then, writing 1 to one of them will update the
PM QoS flags request owned by user space so that the corresponding
flag is requested to be set.  In turn, writing 0 to one of them
will cause the corresponding flag in the user space's request to
be cleared (however, the owners of the other PM QoS flags requests
for the same device may still request the flag to be set and it
may be effectively set even if user space doesn't request that).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jean Pihet <j-pihet@ti.com>
Acked-by: mark gross <markgross@thegnar.org>

Documentation/ABI/testing/sysfs-devices-power

@@ -204,3 +204,34 @@ Description:
 
 		This attribute has no effect on system-wide suspend/resume and
 		hibernation.
+
+What:		/sys/devices/.../power/pm_qos_no_power_off
+Date:		September 2012
+Contact:	Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+		The /sys/devices/.../power/pm_qos_no_power_off attribute
+		is used for manipulating the PM QoS "no power off" flag.  If
+		set, this flag indicates to the kernel that power should not
+		be removed entirely from the device.
+
+		Not all drivers support this attribute.  If it isn't supported,
+		it is not present.
+
+		This attribute has no effect on system-wide suspend/resume and
+		hibernation.
+
+What:		/sys/devices/.../power/pm_qos_remote_wakeup
+Date:		September 2012
+Contact:	Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+		The /sys/devices/.../power/pm_qos_remote_wakeup attribute
+		is used for manipulating the PM QoS "remote wakeup required"
+		flag.  If set, this flag indicates to the kernel that the
+		device is a source of user events that have to be signaled from
+		its low-power states.
+
+		Not all drivers support this attribute.  If it isn't supported,
+		it is not present.
+
+		This attribute has no effect on system-wide suspend/resume and
+		hibernation.

drivers/base/power/power.h

@@ -93,8 +93,10 @@ extern void dpm_sysfs_remove(struct device *dev);
 extern void rpm_sysfs_remove(struct device *dev);
 extern int wakeup_sysfs_add(struct device *dev);
 extern void wakeup_sysfs_remove(struct device *dev);
-extern int pm_qos_sysfs_add(struct device *dev);
-extern void pm_qos_sysfs_remove(struct device *dev);
+extern int pm_qos_sysfs_add_latency(struct device *dev);
+extern void pm_qos_sysfs_remove_latency(struct device *dev);
+extern int pm_qos_sysfs_add_flags(struct device *dev);
+extern void pm_qos_sysfs_remove_flags(struct device *dev);
 
 #else /* CONFIG_PM */
 

drivers/base/power/qos.c

@@ -40,6 +40,7 @@
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/export.h>
+#include <linux/pm_runtime.h>
 
 #include "power.h"
 
@@ -321,6 +322,37 @@ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
 
+/**
+ * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
+ * @req : PM QoS request to modify.
+ * @new_value: New value to request.
+ */
+static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req,
+				       s32 new_value)
+{
+	s32 curr_value;
+	int ret = 0;
+
+	if (!req->dev->power.qos)
+		return -ENODEV;
+
+	switch(req->type) {
+	case DEV_PM_QOS_LATENCY:
+		curr_value = req->data.pnode.prio;
+		break;
+	case DEV_PM_QOS_FLAGS:
+		curr_value = req->data.flr.flags;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (curr_value != new_value)
+		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
+
+	return ret;
+}
+
 /**
  * dev_pm_qos_update_request - modifies an existing qos request
  * @req : handle to list element holding a dev_pm_qos request to use
@@ -336,11 +368,9 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
  * -EINVAL in case of wrong parameters, -ENODEV if the device has been
  * removed from the system
  */
-int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
-			      s32 new_value)
+int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
 {
-	s32 curr_value;
-	int ret = 0;
+	int ret;
 
 	if (!req) /*guard against callers passing in null */
 		return -EINVAL;
@@ -350,29 +380,9 @@ int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
 		return -EINVAL;
 
 	mutex_lock(&dev_pm_qos_mtx);
-
-	if (!req->dev->power.qos) {
-		ret = -ENODEV;
-		goto out;
-	}
-
-	switch(req->type) {
-	case DEV_PM_QOS_LATENCY:
-		curr_value = req->data.pnode.prio;
-		break;
-	case DEV_PM_QOS_FLAGS:
-		curr_value = req->data.flr.flags;
-		break;
-	default:
-		ret = -EINVAL;
-		goto out;
-	}
-
-	if (curr_value != new_value)
-		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
-
- out:
+	__dev_pm_qos_update_request(req, new_value);
 	mutex_unlock(&dev_pm_qos_mtx);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
@@ -533,10 +543,19 @@ int dev_pm_qos_add_ancestor_request(struct device *dev,
 EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
 
 #ifdef CONFIG_PM_RUNTIME
-static void __dev_pm_qos_drop_user_request(struct device *dev)
+static void __dev_pm_qos_drop_user_request(struct device *dev,
+					   enum dev_pm_qos_req_type type)
 {
-	dev_pm_qos_remove_request(dev->power.pq_req);
-	dev->power.pq_req = NULL;
+	switch(type) {
+	case DEV_PM_QOS_LATENCY:
+		dev_pm_qos_remove_request(dev->power.qos->latency_req);
+		dev->power.qos->latency_req = NULL;
+		break;
+	case DEV_PM_QOS_FLAGS:
+		dev_pm_qos_remove_request(dev->power.qos->flags_req);
+		dev->power.qos->flags_req = NULL;
+		break;
+	}
 }
 
 /**
@@ -552,7 +571,7 @@ int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
 	if (!device_is_registered(dev) || value < 0)
 		return -EINVAL;
 
-	if (dev->power.pq_req)
+	if (dev->power.qos && dev->power.qos->latency_req)
 		return -EEXIST;
 
 	req = kzalloc(sizeof(*req), GFP_KERNEL);
@@ -563,10 +582,10 @@ int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
 	if (ret < 0)
 		return ret;
 
-	dev->power.pq_req = req;
-	ret = pm_qos_sysfs_add(dev);
+	dev->power.qos->latency_req = req;
+	ret = pm_qos_sysfs_add_latency(dev);
 	if (ret)
-		__dev_pm_qos_drop_user_request(dev);
+		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
 
 	return ret;
 }
@@ -578,10 +597,87 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
  */
 void dev_pm_qos_hide_latency_limit(struct device *dev)
 {
-	if (dev->power.pq_req) {
-		pm_qos_sysfs_remove(dev);
-		__dev_pm_qos_drop_user_request(dev);
+	if (dev->power.qos && dev->power.qos->latency_req) {
+		pm_qos_sysfs_remove_latency(dev);
+		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
 	}
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
+
+/**
+ * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space.
+ * @dev: Device whose PM QoS flags are to be exposed to user space.
+ * @val: Initial values of the flags.
+ */
+int dev_pm_qos_expose_flags(struct device *dev, s32 val)
+{
+	struct dev_pm_qos_request *req;
+	int ret;
+
+	if (!device_is_registered(dev))
+		return -EINVAL;
+
+	if (dev->power.qos && dev->power.qos->flags_req)
+		return -EEXIST;
+
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
+	if (ret < 0)
+		return ret;
+
+	dev->power.qos->flags_req = req;
+	ret = pm_qos_sysfs_add_flags(dev);
+	if (ret)
+		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
+
+/**
+ * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space.
+ * @dev: Device whose PM QoS flags are to be hidden from user space.
+ */
+void dev_pm_qos_hide_flags(struct device *dev)
+{
+	if (dev->power.qos && dev->power.qos->flags_req) {
+		pm_qos_sysfs_remove_flags(dev);
+		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
+	}
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
+
+/**
+ * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space.
+ * @dev: Device to update the PM QoS flags request for.
+ * @mask: Flags to set/clear.
+ * @set: Whether to set or clear the flags (true means set).
+ */
+int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
+{
+	s32 value;
+	int ret;
+
+	if (!dev->power.qos || !dev->power.qos->flags_req)
+		return -EINVAL;
+
+	pm_runtime_get_sync(dev);
+	mutex_lock(&dev_pm_qos_mtx);
+
+	value = dev_pm_qos_requested_flags(dev);
+	if (set)
+		value |= mask;
+	else
+		value &= ~mask;
+
+	ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
+
+	mutex_unlock(&dev_pm_qos_mtx);
+	pm_runtime_put(dev);
+
+	return ret;
+}
 #endif /* CONFIG_PM_RUNTIME */