7 files changed, 277 insertions, 44 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
index efe449bdf811..7dbf96b724ed 100644
--- a/Documentation/ABI/testing/sysfs-devices-power
+++ b/Documentation/ABI/testing/sysfs-devices-power
@@ -187,7 +187,7 @@ Description:
                 Not all drivers support this attribute.  If it isn't supported,
                 attempts to read or write it will yield I/O errors.
 
-What:           /sys/devices/.../power/pm_qos_latency_us
+What:           /sys/devices/.../power/pm_qos_resume_latency_us
 Date:           March 2012
 Contact:        Rafael J. Wysocki <rjw@rjwysocki.net>
 Description:
@@ -205,6 +205,31 @@ Description:
                 This attribute has no effect on system-wide suspend/resume and
                 hibernation.
 
+What:           /sys/devices/.../power/pm_qos_latency_tolerance_us
+Date:           January 2014
+Contact:        Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+                The /sys/devices/.../power/pm_qos_latency_tolerance_us attribute
+                contains the PM QoS active state latency tolerance limit for the
+                given device in microseconds.  That is the maximum memory access
+                latency the device can suffer without any visible adverse
+                effects on user space functionality.  If that value is the
+                string "any", the latency does not matter to user space at all,
+                but hardware should not be allowed to set the latency tolerance
+                for the device automatically.
+
+                Reading "auto" from this file means that the maximum memory
+                access latency for the device may be determined automatically
+                by the hardware as needed.  Writing "auto" to it allows the
+                hardware to be switched to this mode if there are no other
+                latency tolerance requirements from the kernel side.
+
+                This attribute is only present if the feature controlled by it
+                is supported by the hardware.
+
+                This attribute has no effect on runtime suspend and resume of
+                devices and on system-wide suspend/resume and hibernation.
+
 What:           /sys/devices/.../power/pm_qos_no_power_off
 Date:           September 2012
 Contact:        Rafael J. Wysocki <rjw@rjwysocki.net>
diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
index 22cb8f51182a..ed743bbad87c 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -88,17 +88,19 @@ node.
 
 2. PM QoS per-device latency and flags framework
 
-For each device, there are two lists of PM QoS requests. One is maintained
-along with the aggregated target of resume latency value and the other is for
-PM QoS flags. Values are updated in response to changes of the request list.
+For each device, there are three lists of PM QoS requests. Two of them are
+maintained along with the aggregated targets of resume latency and active
+state latency tolerance (in microseconds) and the third one is for PM QoS flags.
+Values are updated in response to changes of the request list.
 
-Target resume latency value is simply the minimum of the request values held in
-the parameter list elements.  The PM QoS flags aggregate value is a gather
-(bitwise OR) of all list elements' values.  Two device PM QoS flags are defined
-currently: PM_QOS_FLAG_NO_POWER_OFF and PM_QOS_FLAG_REMOTE_WAKEUP.
+The target values of resume latency and active state latency tolerance are
+simply the minimum of the request values held in the parameter list elements.
+The PM QoS flags aggregate value is a gather (bitwise OR) of all list elements'
+values.  Two device PM QoS flags are defined currently: PM_QOS_FLAG_NO_POWER_OFF
+and PM_QOS_FLAG_REMOTE_WAKEUP.
 
-Note: the aggregated target value is implemented in such a way that reading the
-aggregated value does not require any locking mechanism.
+Note: The aggregated target values are implemented in such a way that reading
+the aggregated value does not require any locking mechanism.
 
 
 From kernel mode the use of this interface is the following:
@@ -177,3 +179,42 @@ The callback is called when the aggregated value for any device is changed
 int dev_pm_qos_remove_global_notifier(notifier):
 Removes the notification callback function from the global notification tree
 of the framework.
+
+
+Active state latency tolerance
+
+This device PM QoS type is used to support systems in which hardware may switch
+to energy-saving operation modes on the fly.  In those systems, if the operation
+mode chosen by the hardware attempts to save energy in an overly aggressive way,
+it may cause excess latencies to be visible to software, causing it to miss
+certain protocol requirements or target frame or sample rates etc.
+
+If there is a latency tolerance control mechanism for a given device available
+to software, the .set_latency_tolerance callback in that device's dev_pm_info
+structure should be populated.  The routine pointed to by it is should implement
+whatever is necessary to transfer the effective requirement value to the
+hardware.
+
+Whenever the effective latency tolerance changes for the device, its
+.set_latency_tolerance() callback will be executed and the effective value will
+be passed to it.  If that value is negative, which means that the list of
+latency tolerance requirements for the device is empty, the callback is expected
+to switch the underlying hardware latency tolerance control mechanism to an
+autonomous mode if available.  If that value is PM_QOS_LATENCY_ANY, in turn, and
+the hardware supports a special "no requirement" setting, the callback is
+expected to use it.  That allows software to prevent the hardware from
+automatically updating the device's latency tolerance in response to its power
+state changes (e.g. during transitions from D3cold to D0), which generally may
+be done in the autonomous latency tolerance control mode.
+
+If .set_latency_tolerance() is present for the device, sysfs attribute
+pm_qos_latency_tolerance_us will be present in the devivce's power directory.
+Then, user space can use that attribute to specify its latency tolerance
+requirement for the device, if any.  Writing "any" to it means "no requirement,
+but do not let the hardware control latency tolerance" and writing "auto" to it
+allows the hardware to be switched to the autonomous mode if there are no other
+requirements from the kernel side in the device's list.
+
+Kernel code can use the functions described above along with the
+DEV_PM_QOS_LATENCY_TOLERANCE device PM QoS type to add, remove and update
+latency tolerance requirements for devices.
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index c754e55f9dcb..84756f7f09d9 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -151,6 +151,14 @@ static int apply_constraint(struct dev_pm_qos_request *req,
                                                      req);
                 }
                 break;
+        case DEV_PM_QOS_LATENCY_TOLERANCE:
+                ret = pm_qos_update_target(&qos->latency_tolerance,
+                                           &req->data.pnode, action, value);
+                if (ret) {
+                        value = pm_qos_read_value(&qos->latency_tolerance);
+                        req->dev->power.set_latency_tolerance(req->dev, value);
+                }
+                break;
         case DEV_PM_QOS_FLAGS:
                 ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
                                           action, value);
@@ -194,6 +202,13 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
         c->type = PM_QOS_MIN;
         c->notifiers = n;
 
+        c = &qos->latency_tolerance;
+        plist_head_init(&c->list);
+        c->target_value = PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE;
+        c->default_value = PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE;
+        c->no_constraint_value = PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT;
+        c->type = PM_QOS_MIN;
+
         INIT_LIST_HEAD(&qos->flags.list);
 
         spin_lock_irq(&dev->power.lock);
@@ -247,6 +262,11 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
                 apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
                 memset(req, 0, sizeof(*req));
         }
+        c = &qos->latency_tolerance;
+        plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) {
+                apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
+                memset(req, 0, sizeof(*req));
+        }
         f = &qos->flags;
         list_for_each_entry_safe(req, tmp, &f->list, data.flr.node) {
                 apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
@@ -266,6 +286,40 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
         mutex_unlock(&dev_pm_qos_sysfs_mtx);
 }
 
+static bool dev_pm_qos_invalid_request(struct device *dev,
+                                       struct dev_pm_qos_request *req)
+{
+        return !req || (req->type == DEV_PM_QOS_LATENCY_TOLERANCE
+                        && !dev->power.set_latency_tolerance);
+}
+
+static int __dev_pm_qos_add_request(struct device *dev,
+                                    struct dev_pm_qos_request *req,
+                                    enum dev_pm_qos_req_type type, s32 value)
+{
+        int ret = 0;
+
+        if (!dev || dev_pm_qos_invalid_request(dev, req))
+                return -EINVAL;
+
+        if (WARN(dev_pm_qos_request_active(req),
+                 "%s() called for already added request\n", __func__))
+                return -EINVAL;
+
+        if (IS_ERR(dev->power.qos))
+                ret = -ENODEV;
+        else if (!dev->power.qos)
+                ret = dev_pm_qos_constraints_allocate(dev);
+
+        trace_dev_pm_qos_add_request(dev_name(dev), type, value);
+        if (!ret) {
+                req->dev = dev;
+                req->type = type;
+                ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
+        }
+        return ret;
+}
+
 /**
  * dev_pm_qos_add_request - inserts new qos request into the list
  * @dev: target device for the constraint
@@ -291,31 +345,11 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
                            enum dev_pm_qos_req_type type, s32 value)
 {
-        int ret = 0;
-
-        if (!dev || !req) /*guard against callers passing in null */
-                return -EINVAL;
-
-        if (WARN(dev_pm_qos_request_active(req),
-                 "%s() called for already added request\n", __func__))
-                return -EINVAL;
+        int ret;
 
         mutex_lock(&dev_pm_qos_mtx);
-
-        if (IS_ERR(dev->power.qos))
-                ret = -ENODEV;
-        else if (!dev->power.qos)
-                ret = dev_pm_qos_constraints_allocate(dev);
-
-        trace_dev_pm_qos_add_request(dev_name(dev), type, value);
-        if (!ret) {
-                req->dev = dev;
-                req->type = type;
-                ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
-        }
-
+        ret = __dev_pm_qos_add_request(dev, req, type, value);
         mutex_unlock(&dev_pm_qos_mtx);
-
         return ret;
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
@@ -343,6 +377,7 @@ static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req,
 
         switch(req->type) {
         case DEV_PM_QOS_RESUME_LATENCY:
+        case DEV_PM_QOS_LATENCY_TOLERANCE:
                 curr_value = req->data.pnode.prio;
                 break;
         case DEV_PM_QOS_FLAGS:
@@ -563,6 +598,10 @@ static void __dev_pm_qos_drop_user_request(struct device *dev,
                 req = dev->power.qos->resume_latency_req;
                 dev->power.qos->resume_latency_req = NULL;
                 break;
+        case DEV_PM_QOS_LATENCY_TOLERANCE:
+                req = dev->power.qos->latency_tolerance_req;
+                dev->power.qos->latency_tolerance_req = NULL;
+                break;
         case DEV_PM_QOS_FLAGS:
                 req = dev->power.qos->flags_req;
                 dev->power.qos->flags_req = NULL;
@@ -768,6 +807,67 @@ int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
         pm_runtime_put(dev);
         return ret;
 }
+
+/**
+ * dev_pm_qos_get_user_latency_tolerance - Get user space latency tolerance.
+ * @dev: Device to obtain the user space latency tolerance for.
+ */
+s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev)
+{
+        s32 ret;
+
+        mutex_lock(&dev_pm_qos_mtx);
+        ret = IS_ERR_OR_NULL(dev->power.qos)
+                || !dev->power.qos->latency_tolerance_req ?
+                        PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT :
+                        dev->power.qos->latency_tolerance_req->data.pnode.prio;
+        mutex_unlock(&dev_pm_qos_mtx);
+        return ret;
+}
+
+/**
+ * dev_pm_qos_update_user_latency_tolerance - Update user space latency tolerance.
+ * @dev: Device to update the user space latency tolerance for.
+ * @val: New user space latency tolerance for @dev (negative values disable).
+ */
+int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val)
+{
+        int ret;
+
+        mutex_lock(&dev_pm_qos_mtx);
+
+        if (IS_ERR_OR_NULL(dev->power.qos)
+            || !dev->power.qos->latency_tolerance_req) {
+                struct dev_pm_qos_request *req;
+
+                if (val < 0) {
+                        ret = -EINVAL;
+                        goto out;
+                }
+                req = kzalloc(sizeof(*req), GFP_KERNEL);
+                if (!req) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+                ret = __dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY_TOLERANCE, val);
+                if (ret < 0) {
+                        kfree(req);
+                        goto out;
+                }
+                dev->power.qos->latency_tolerance_req = req;
+        } else {
+                if (val < 0) {
+                        __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY_TOLERANCE);
+                        ret = 0;
+                } else {
+                        ret = __dev_pm_qos_update_request(dev->power.qos->latency_tolerance_req, val);
+                }
+        }
+
+ out:
+        mutex_unlock(&dev_pm_qos_mtx);
+        return ret;
+}
 #else /* !CONFIG_PM_RUNTIME */
 static void __dev_pm_qos_hide_latency_limit(struct device *dev) {}
 static void __dev_pm_qos_hide_flags(struct device *dev) {}
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 4e24955aac8a..95b181d1ca6d 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -246,6 +246,40 @@ static ssize_t pm_qos_resume_latency_store(struct device *dev,
 static DEVICE_ATTR(pm_qos_resume_latency_us, 0644,
                    pm_qos_resume_latency_show, pm_qos_resume_latency_store);
 
+static ssize_t pm_qos_latency_tolerance_show(struct device *dev,
+                                             struct device_attribute *attr,
+                                             char *buf)
+{
+        s32 value = dev_pm_qos_get_user_latency_tolerance(dev);
+
+        if (value < 0)
+                return sprintf(buf, "auto\n");
+        else if (value == PM_QOS_LATENCY_ANY)
+                return sprintf(buf, "any\n");
+
+        return sprintf(buf, "%d\n", value);
+}
+
+static ssize_t pm_qos_latency_tolerance_store(struct device *dev,
+                                              struct device_attribute *attr,
+                                              const char *buf, size_t n)
+{
+        s32 value;
+        int ret;
+
+        if (kstrtos32(buf, 0, &value)) {
+                if (!strcmp(buf, "auto") || !strcmp(buf, "auto\n"))
+                        value = PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT;
+                else if (!strcmp(buf, "any") || !strcmp(buf, "any\n"))
+                        value = PM_QOS_LATENCY_ANY;
+        }
+        ret = dev_pm_qos_update_user_latency_tolerance(dev, value);
+        return ret < 0 ? ret : n;
+}
+
+static DEVICE_ATTR(pm_qos_latency_tolerance_us, 0644,
+                   pm_qos_latency_tolerance_show, pm_qos_latency_tolerance_store);
+
 static ssize_t pm_qos_no_power_off_show(struct device *dev,
                                         struct device_attribute *attr,
                                         char *buf)
@@ -631,6 +665,17 @@ static struct attribute_group pm_qos_resume_latency_attr_group = {
         .attrs  = pm_qos_resume_latency_attrs,
 };
 
+static struct attribute *pm_qos_latency_tolerance_attrs[] = {
+#ifdef CONFIG_PM_RUNTIME
+        &dev_attr_pm_qos_latency_tolerance_us.attr,
+#endif /* CONFIG_PM_RUNTIME */
+        NULL,
+};
+static struct attribute_group pm_qos_latency_tolerance_attr_group = {
+        .name   = power_group_name,
+        .attrs  = pm_qos_latency_tolerance_attrs,
+};
+
 static struct attribute *pm_qos_flags_attrs[] = {
 #ifdef CONFIG_PM_RUNTIME
         &dev_attr_pm_qos_no_power_off.attr,
@@ -656,18 +701,23 @@ int dpm_sysfs_add(struct device *dev)
                 if (rc)
                         goto err_out;
         }
-
         if (device_can_wakeup(dev)) {
                 rc = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
-                if (rc) {
-                        if (pm_runtime_callbacks_present(dev))
-                                sysfs_unmerge_group(&dev->kobj,
-                                                    &pm_runtime_attr_group);
-                        goto err_out;
-                }
+                if (rc)
+                        goto err_runtime;
+        }
+        if (dev->power.set_latency_tolerance) {
+                rc = sysfs_merge_group(&dev->kobj,
+                                       &pm_qos_latency_tolerance_attr_group);
+                if (rc)
+                        goto err_wakeup;
         }
         return 0;
 
+ err_wakeup:
+        sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
+ err_runtime:
+        sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group);
  err_out:
         sysfs_remove_group(&dev->kobj, &pm_attr_group);
         return rc;
@@ -710,6 +760,7 @@ void rpm_sysfs_remove(struct device *dev)
 
 void dpm_sysfs_remove(struct device *dev)
 {
+        sysfs_unmerge_group(&dev->kobj, &pm_qos_latency_tolerance_attr_group);
         dev_pm_qos_constraints_destroy(dev);
         rpm_sysfs_remove(dev);
         sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 8c6583a53a06..db2be5f3e030 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -582,6 +582,7 @@ struct dev_pm_info {
         unsigned long           accounting_timestamp;
 #endif
         struct pm_subsys_data   *subsys_data;  /* Owned by the subsystem. */
+        void (*set_latency_tolerance)(struct device *, s32);
         struct dev_pm_qos       *qos;
 };
 
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 2d8ce50877d8..0b476019be55 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -33,6 +33,9 @@ enum pm_qos_flags_status {
 #define PM_QOS_NETWORK_LAT_DEFAULT_VALUE        (2000 * USEC_PER_SEC)
 #define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
 #define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE     0
+#define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE  0
+#define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT  (-1)
+#define PM_QOS_LATENCY_ANY                      ((s32)(~(__u32)0 >> 1))
 
 #define PM_QOS_FLAG_NO_POWER_OFF        (1 << 0)
 #define PM_QOS_FLAG_REMOTE_WAKEUP       (1 << 1)
@@ -50,6 +53,7 @@ struct pm_qos_flags_request {
 
 enum dev_pm_qos_req_type {
         DEV_PM_QOS_RESUME_LATENCY = 1,
+        DEV_PM_QOS_LATENCY_TOLERANCE,
         DEV_PM_QOS_FLAGS,
 };
 
@@ -89,8 +93,10 @@ struct pm_qos_flags {
 
 struct dev_pm_qos {
         struct pm_qos_constraints resume_latency;
+        struct pm_qos_constraints latency_tolerance;
         struct pm_qos_flags flags;
         struct dev_pm_qos_request *resume_latency_req;
+        struct dev_pm_qos_request *latency_tolerance_req;
         struct dev_pm_qos_request *flags_req;
 };
 
@@ -196,6 +202,8 @@ void dev_pm_qos_hide_latency_limit(struct device *dev);
 int dev_pm_qos_expose_flags(struct device *dev, s32 value);
 void dev_pm_qos_hide_flags(struct device *dev);
 int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set);
+s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev);
+int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val);
 
 static inline s32 dev_pm_qos_requested_resume_latency(struct device *dev)
 {
@@ -215,6 +223,10 @@ static inline int dev_pm_qos_expose_flags(struct device *dev, s32 value)
 static inline void dev_pm_qos_hide_flags(struct device *dev) {}
 static inline int dev_pm_qos_update_flags(struct device *dev, s32 m, bool set)
                         { return 0; }
+static inline s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev)
+                        { return PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT; }
+static inline int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val)
+                        { return 0; }
 
 static inline s32 dev_pm_qos_requested_resume_latency(struct device *dev) { return 0; }
 static inline s32 dev_pm_qos_requested_flags(struct device *dev) { return 0; }
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index e23ae38e647f..884b77058864 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -173,6 +173,7 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 {
         unsigned long flags;
         int prev_value, curr_value, new_value;
+        int ret;
 
         spin_lock_irqsave(&pm_qos_lock, flags);
         prev_value = pm_qos_get_value(c);
@@ -208,13 +209,15 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 
         trace_pm_qos_update_target(action, prev_value, curr_value);
         if (prev_value != curr_value) {
-                blocking_notifier_call_chain(c->notifiers,
-                                             (unsigned long)curr_value,
-                                             NULL);
-                return 1;
+                ret = 1;
+                if (c->notifiers)
+                        blocking_notifier_call_chain(c->notifiers,
+                                                     (unsigned long)curr_value,
+                                                     NULL);
         } else {
-                return 0;
+                ret = 0;
         }
+        return ret;
 }
 
 /**