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>
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@ -11,7 +11,7 @@ What: /sys/class/devfreq/.../governor
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Date: September 2011
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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The /sys/class/devfreq/.../governor shows the name of the
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The /sys/class/devfreq/.../governor show or set the name of the
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governor used by the corresponding devfreq object.
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What: /sys/class/devfreq/.../cur_freq
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@ -688,6 +688,49 @@ static ssize_t show_governor(struct device *dev,
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return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
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}
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static ssize_t store_governor(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct devfreq *df = to_devfreq(dev);
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int ret;
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char str_governor[DEVFREQ_NAME_LEN + 1];
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struct devfreq_governor *governor;
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ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
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if (ret != 1)
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return -EINVAL;
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mutex_lock(&devfreq_list_lock);
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governor = find_devfreq_governor(str_governor);
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if (IS_ERR(governor)) {
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ret = PTR_ERR(governor);
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goto out;
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}
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if (df->governor == governor)
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goto out;
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if (df->governor) {
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ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
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if (ret) {
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dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
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__func__, df->governor->name, ret);
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goto out;
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}
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}
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df->governor = governor;
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strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
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ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
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if (ret)
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dev_warn(dev, "%s: Governor %s not started(%d)\n",
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__func__, df->governor->name, ret);
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out:
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mutex_unlock(&devfreq_list_lock);
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if (!ret)
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ret = count;
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return ret;
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}
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static ssize_t show_freq(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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@ -873,7 +916,7 @@ static ssize_t show_trans_table(struct device *dev, struct device_attribute *att
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}
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static struct device_attribute devfreq_attrs[] = {
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__ATTR(governor, S_IRUGO, show_governor, NULL),
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__ATTR(governor, S_IRUGO | S_IWUSR, show_governor, store_governor),
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__ATTR(cur_freq, S_IRUGO, show_freq, NULL),
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__ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL),
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__ATTR(target_freq, S_IRUGO, show_target_freq, NULL),
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