From 0359d1afe4013d1a216908b6be4c6695a1db6fd6 Mon Sep 17 00:00:00 2001 From: Nishanth Menon 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 Cc: MyungJoo Ham Cc: Kyungmin Park Cc: "Rafael J. Wysocki" Cc: Kevin Hilman Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Nishanth Menon Acked-by: MyungJoo Ham Signed-off-by: MyungJoo Ham --- 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 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),