PM / devfreq: Add PM QoS support

Register notifiers with the PM QoS framework in order to respond to
requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY.

No notifiers are added by this patch but PM QoS constraints can be
imposed externally (for example from other devices).

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 59f9fa8b54d10e94fc272be0a096bb4f99e92ddf..f6e2720854482099537082e4f5456b362ab3b831 100644 (file)
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -24,11 +24,14 @@
 #include <linux/printk.h>
 #include <linux/hrtimer.h>
 #include <linux/of.h>
+#include <linux/pm_qos.h>
 #include "governor.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/devfreq.h>
 
+#define HZ_PER_KHZ     1000
+
 static struct class *devfreq_class;
 
 /*
@@ -111,6 +114,7 @@ static void get_freq_range(struct devfreq *devfreq,
                           unsigned long *max_freq)
 {
        unsigned long *freq_table = devfreq->profile->freq_table;
+       s32 qos_min_freq, qos_max_freq;
 
        lockdep_assert_held(&devfreq->lock);
 
@@ -127,6 +131,16 @@ static void get_freq_range(struct devfreq *devfreq,
                *max_freq = freq_table[0];
        }
 
+       /* Apply constraints from PM QoS */
+       qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
+                                            DEV_PM_QOS_MIN_FREQUENCY);
+       qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
+                                            DEV_PM_QOS_MAX_FREQUENCY);
+       *min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
+       if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
+               *max_freq = min(*max_freq,
+                               (unsigned long)HZ_PER_KHZ * qos_max_freq);
+
        /* Apply constraints from sysfs */
        *min_freq = max(*min_freq, devfreq->min_freq);
        *max_freq = min(*max_freq, devfreq->max_freq);
@@ -626,6 +640,45 @@ out:
        return NOTIFY_OK;
 }
 
+/**
+ * qos_notifier_call() - Common handler for QoS constraints.
+ * @devfreq:    the devfreq instance.
+ */
+static int qos_notifier_call(struct devfreq *devfreq)
+{
+       int err;
+
+       mutex_lock(&devfreq->lock);
+       err = update_devfreq(devfreq);
+       mutex_unlock(&devfreq->lock);
+       if (err)
+               dev_err(devfreq->dev.parent,
+                       "failed to update frequency from PM QoS (%d)\n",
+                       err);
+
+       return NOTIFY_OK;
+}
+
+/**
+ * qos_min_notifier_call() - Callback for QoS min_freq changes.
+ * @nb:                Should be devfreq->nb_min
+ */
+static int qos_min_notifier_call(struct notifier_block *nb,
+                                        unsigned long val, void *ptr)
+{
+       return qos_notifier_call(container_of(nb, struct devfreq, nb_min));
+}
+
+/**
+ * qos_max_notifier_call() - Callback for QoS max_freq changes.
+ * @nb:                Should be devfreq->nb_max
+ */
+static int qos_max_notifier_call(struct notifier_block *nb,
+                                        unsigned long val, void *ptr)
+{
+       return qos_notifier_call(container_of(nb, struct devfreq, nb_max));
+}
+
 /**
  * devfreq_dev_release() - Callback for struct device to release the device.
  * @dev:       the devfreq device
@@ -635,11 +688,23 @@ out:
 static void devfreq_dev_release(struct device *dev)
 {
        struct devfreq *devfreq = to_devfreq(dev);
+       int err;
 
        mutex_lock(&devfreq_list_lock);
        list_del(&devfreq->node);
        mutex_unlock(&devfreq_list_lock);
 
+       err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
+                                        DEV_PM_QOS_MAX_FREQUENCY);
+       if (err && err != -ENOENT)
+               dev_warn(dev->parent,
+                       "Failed to remove max_freq notifier: %d\n", err);
+       err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
+                                        DEV_PM_QOS_MIN_FREQUENCY);
+       if (err && err != -ENOENT)
+               dev_warn(dev->parent,
+                       "Failed to remove min_freq notifier: %d\n", err);
+
        if (devfreq->profile->exit)
                devfreq->profile->exit(devfreq->dev.parent);
 
@@ -762,6 +827,18 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
        mutex_unlock(&devfreq->lock);
 
+       devfreq->nb_min.notifier_call = qos_min_notifier_call;
+       err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min,
+                                     DEV_PM_QOS_MIN_FREQUENCY);
+       if (err)
+               goto err_devfreq;
+
+       devfreq->nb_max.notifier_call = qos_max_notifier_call;
+       err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_max,
+                                     DEV_PM_QOS_MAX_FREQUENCY);
+       if (err)
+               goto err_devfreq;
+
        mutex_lock(&devfreq_list_lock);
 
        governor = try_then_request_governor(devfreq->governor_name);

diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 2bae9ed3c7831cfe1a22e1e33e411165c520d87a..8b92ccbd1962d71076ef3bd6a4b31e009781daff 100644 (file)
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -136,6 +136,8 @@ struct devfreq_dev_profile {
  * @time_in_state:     Statistics of devfreq states
  * @last_stat_updated: The last time stat updated
  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
+ * @nb_min:            Notifier block for DEV_PM_QOS_MIN_FREQUENCY
+ * @nb_max:            Notifier block for DEV_PM_QOS_MAX_FREQUENCY
  *
  * This structure stores the devfreq information for a give device.
  *
@@ -178,6 +180,9 @@ struct devfreq {
        unsigned long last_stat_updated;
 
        struct srcu_notifier_head transition_notifier_list;
+
+       struct notifier_block nb_min;
+       struct notifier_block nb_max;
 };
 
 struct devfreq_freqs {