PM / devfreq: add min/max_freq limit requested by users.

The frequency requested to devfreq device driver from devfreq governors
is restricted by min_freq and max_freq input.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index c189b82f5ece..a129a7b6bfd1 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -501,12 +501,82 @@ static ssize_t show_central_polling(struct device *dev,
                        !to_devfreq(dev)->governor->no_central_polling);
 }
 
+static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr,
+                              const char *buf, size_t count)
+{
+        struct devfreq *df = to_devfreq(dev);
+        unsigned long value;
+        int ret;
+        unsigned long max;
+
+        ret = sscanf(buf, "%lu", &value);
+        if (ret != 1)
+                goto out;
+
+        mutex_lock(&df->lock);
+        max = df->max_freq;
+        if (value && max && value > max) {
+                ret = -EINVAL;
+                goto unlock;
+        }
+
+        df->min_freq = value;
+        update_devfreq(df);
+        ret = count;
+unlock:
+        mutex_unlock(&df->lock);
+out:
+        return ret;
+}
+
+static ssize_t show_min_freq(struct device *dev, struct device_attribute *attr,
+                             char *buf)
+{
+        return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
+}
+
+static ssize_t store_max_freq(struct device *dev, struct device_attribute *attr,
+                              const char *buf, size_t count)
+{
+        struct devfreq *df = to_devfreq(dev);
+        unsigned long value;
+        int ret;
+        unsigned long min;
+
+        ret = sscanf(buf, "%lu", &value);
+        if (ret != 1)
+                goto out;
+
+        mutex_lock(&df->lock);
+        min = df->min_freq;
+        if (value && min && value < min) {
+                ret = -EINVAL;
+                goto unlock;
+        }
+
+        df->max_freq = value;
+        update_devfreq(df);
+        ret = count;
+unlock:
+        mutex_unlock(&df->lock);
+out:
+        return ret;
+}
+
+static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr,
+                             char *buf)
+{
+        return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
+}
+
 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),
+        __ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),
+        __ATTR(max_freq, S_IRUGO | S_IWUSR, show_max_freq, store_max_freq),
         { },
 };