PM / devfreq: Add sysfs node to expose available governors

Now that governor list can be variable, knowing the available governors
is useful to be able to select a governor using relevant sysfs node.

Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Kevin Hilman <khilman@ti.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index ff960f084c11..45e053e5b139 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -730,6 +730,27 @@ out:
                 ret = count;
         return ret;
 }
+static ssize_t show_available_governors(struct device *d,
+                                    struct device_attribute *attr,
+                                    char *buf)
+{
+        struct devfreq_governor *tmp_governor;
+        ssize_t count = 0;
+
+        mutex_lock(&devfreq_list_lock);
+        list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
+                count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
+                                   "%s ", tmp_governor->name);
+        mutex_unlock(&devfreq_list_lock);
+
+        /* Truncate the trailing space */
+        if (count)
+                count--;
+
+        count += sprintf(&buf[count], "\n");
+
+        return count;
+}
 
 static ssize_t show_freq(struct device *dev,
                          struct device_attribute *attr, char *buf)
@@ -917,6 +938,7 @@ static ssize_t show_trans_table(struct device *dev, struct device_attribute *att
 
 static struct device_attribute devfreq_attrs[] = {
         __ATTR(governor, S_IRUGO | S_IWUSR, show_governor, store_governor),
+        __ATTR(available_governors, S_IRUGO, show_available_governors, NULL),
         __ATTR(cur_freq, S_IRUGO, show_freq, NULL),
         __ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL),
         __ATTR(target_freq, S_IRUGO, show_target_freq, NULL),