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PM / devfreq: allow sysfs governor node to switch governor

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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>
This commit is contained in:
Nishanth Menon 2012-10-29 15:01:47 -05:00 committed by MyungJoo Ham
parent eff607fdb1
commit 0359d1afe4
2 changed files with 45 additions and 2 deletions
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2
Documentation/ABI/testing/sysfs-class-devfreq
View file

@ -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

45
drivers/devfreq/devfreq.c
View file

@ -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),