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| author | Nishanth Menon <nm@ti.com> | 2012-10-26 04:48:59 +0400 |
|---|---|---|
| committer | MyungJoo Ham <myungjoo.ham@samsung.com> | 2012-11-20 10:59:32 +0400 |
| commit | d287de855f97c56ca7146ff627e652bd7cd64f3f (patch) | |
| tree | a3dbeb4937853cf1e81dca65c97c2dbbda549129 | |
| parent | e09651fcc295a7dc802f38d9494f5b860dd90bca (diff) | |
| download | linux-d287de855f97c56ca7146ff627e652bd7cd64f3f.tar.xz | |
PM / devfreq: Add sysfs node to expose available frequencies
devfreq governors such as ondemand are controlled by a min and
max frequency, while governors like userspace governor allow us
to set a specific frequency.
However, for the same specific device, depending on the SoC, the
available frequencies can vary.
So expose the available frequencies as a snapshot over sysfs to
allow informed decisions.
This was inspired by cpufreq framework's equivalent for similar
usage sysfs node: scaling_available_frequencies.
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>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-devfreq | 9 | ||||
| -rw-r--r-- | drivers/devfreq/devfreq.c | 32 |
2 files changed, 41 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq index e6cf08e6734d..e672ccb02e7f 100644 --- a/Documentation/ABI/testing/sysfs-class-devfreq +++ b/Documentation/ABI/testing/sysfs-class-devfreq @@ -51,3 +51,12 @@ Description: The /sys/class/devfreq/.../userspace/set_freq shows and sets the requested frequency for the devfreq object if userspace governor is in effect. + +What: /sys/class/devfreq/.../available_frequencies +Date: October 2012 +Contact: Nishanth Menon <nm@ti.com> +Description: + The /sys/class/devfreq/.../available_frequencies shows + the available frequencies of the corresponding devfreq object. + This is a snapshot of available frequencies and not limited + by the min/max frequency restrictions. diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 789af4ff5c9c..c44e562bdfe0 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -570,9 +570,41 @@ static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr, return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq); } +static ssize_t show_available_freqs(struct device *d, + struct device_attribute *attr, + char *buf) +{ + struct devfreq *df = to_devfreq(d); + struct device *dev = df->dev.parent; + struct opp *opp; + ssize_t count = 0; + unsigned long freq = 0; + + rcu_read_lock(); + do { + opp = opp_find_freq_ceil(dev, &freq); + if (IS_ERR(opp)) + break; + + count += scnprintf(&buf[count], (PAGE_SIZE - count - 2), + "%lu ", freq); + freq++; + } while (1); + rcu_read_unlock(); + + /* Truncate the trailing space */ + if (count) + count--; + + count += sprintf(&buf[count], "\n"); + + return count; +} + static struct device_attribute devfreq_attrs[] = { __ATTR(governor, S_IRUGO, show_governor, NULL), __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), __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval, store_polling_interval), |