From 0359d1afe4013d1a216908b6be4c6695a1db6fd6 Mon Sep 17 00:00:00 2001
From: Nishanth Menon <nm@ti.com>
Date: Mon, 29 Oct 2012 15:01:47 -0500
Subject: [PATCH] PM / devfreq: allow sysfs governor node to switch governor
This allows us to select governor runtime from the
default configuration without having to rebuild kernel
or the devfreq driver using the sysfs node:
/sys/class/devfreq/.../governor
cat of the governor will return valid governor
and an echo 'governor_name'>governor will switch
governor
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>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
---
Documentation/ABI/testing/sysfs-class-devfreq | 2 +-
drivers/devfreq/devfreq.c | 45 ++++++++++++++++++-
2 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index 40f98a9428dc..66876debca18 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -11,7 +11,7 @@ What: /sys/class/devfreq/.../governor
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
- The /sys/class/devfreq/.../governor shows the name of the
+ The /sys/class/devfreq/.../governor show or set the name of the
governor used by the corresponding devfreq object.
What: /sys/class/devfreq/.../cur_freq
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 0d7be03d561f..ff960f084c11 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -688,6 +688,49 @@ static ssize_t show_governor(struct device *dev,
return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
}
+static ssize_t store_governor(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct devfreq *df = to_devfreq(dev);
+ int ret;
+ char str_governor[DEVFREQ_NAME_LEN + 1];
+ struct devfreq_governor *governor;
+
+ ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
+ if (ret != 1)
+ return -EINVAL;
+
+ mutex_lock(&devfreq_list_lock);
+ governor = find_devfreq_governor(str_governor);
+ if (IS_ERR(governor)) {
+ ret = PTR_ERR(governor);
+ goto out;
+ }
+ if (df->governor == governor)
+ goto out;
+
+ if (df->governor) {
+ ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
+ if (ret) {
+ dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
+ __func__, df->governor->name, ret);
+ goto out;
+ }
+ }
+ df->governor = governor;
+ strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
+ ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
+ if (ret)
+ dev_warn(dev, "%s: Governor %s not started(%d)\n",
+ __func__, df->governor->name, ret);
+out:
+ mutex_unlock(&devfreq_list_lock);
+
+ if (!ret)
+ ret = count;
+ return ret;
+}
+
static ssize_t show_freq(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -873,7 +916,7 @@ static ssize_t show_trans_table(struct device *dev, struct device_attribute *att
}
static struct device_attribute devfreq_attrs[] = {
- __ATTR(governor, S_IRUGO, show_governor, NULL),
+ __ATTR(governor, S_IRUGO | S_IWUSR, show_governor, store_governor),
__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),
--
2.34.1