PM / devfreq: Add common sysfs interfaces

Device specific sysfs interface /sys/devices/.../power/devfreq_*
- governor	R: name of governor
- cur_freq	R: current frequency
- polling_interval	R: polling interval in ms given with devfreq profile
			W: update polling interval.
- central_polling	R: 1 if polling is managed by devfreq framework

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mike Turquette <mturquette@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
--
 Documentation/ABI/testing/sysfs-class-devfreq |   44 ++++++++++++++++
 drivers/devfreq/devfreq.c                     |   69 ++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-devfreq

1 files changed, 69 insertions, 0 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index f3100b19f798..5d15b812377b 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -437,6 +437,74 @@ int devfreq_remove_device(struct devfreq *devfreq)
         return 0;
 }
 
+static ssize_t show_governor(struct device *dev,
+                             struct device_attribute *attr, char *buf)
+{
+        return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
+}
+
+static ssize_t show_freq(struct device *dev,
+                         struct device_attribute *attr, char *buf)
+{
+        return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
+}
+
+static ssize_t show_polling_interval(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+        return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
+}
+
+static ssize_t store_polling_interval(struct device *dev,
+                                      struct device_attribute *attr,
+                                      const char *buf, size_t count)
+{
+        struct devfreq *df = to_devfreq(dev);
+        unsigned int value;
+        int ret;
+
+        ret = sscanf(buf, "%u", &value);
+        if (ret != 1)
+                goto out;
+
+        mutex_lock(&df->lock);
+        df->profile->polling_ms = value;
+        df->next_polling = df->polling_jiffies
+                         = msecs_to_jiffies(value);
+        mutex_unlock(&df->lock);
+
+        ret = count;
+
+        if (df->governor->no_central_polling)
+                goto out;
+
+        mutex_lock(&devfreq_list_lock);
+        if (df->next_polling > 0 && !polling) {
+                polling = true;
+                queue_delayed_work(devfreq_wq, &devfreq_work,
+                                   df->next_polling);
+        }
+        mutex_unlock(&devfreq_list_lock);
+out:
+        return ret;
+}
+
+static ssize_t show_central_polling(struct device *dev,
+                                    struct device_attribute *attr, char *buf)
+{
+        return sprintf(buf, "%d\n",
+                       !to_devfreq(dev)->governor->no_central_polling);
+}
+
+static struct device_attribute devfreq_attrs[] = {
+        __ATTR(governor, S_IRUGO, show_governor, NULL),
+        __ATTR(cur_freq, S_IRUGO, show_freq, NULL),
+        __ATTR(central_polling, S_IRUGO, show_central_polling, NULL),
+        __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
+               store_polling_interval),
+        { },
+};
+
 /**
  * devfreq_start_polling() - Initialize data structure for devfreq framework and
  *                         start polling registered devfreq devices.
@@ -461,6 +529,7 @@ static int __init devfreq_init(void)
                 pr_err("%s: couldn't create class\n", __FILE__);
                 return PTR_ERR(devfreq_class);
         }
+        devfreq_class->dev_attrs = devfreq_attrs;
         return 0;
 }
 subsys_initcall(devfreq_init);