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authorNishanth Menon <nm@ti.com>2012-10-25 19:48:59 -0500
committerMyungJoo Ham <myungjoo.ham@samsung.com>2012-11-20 15:59:32 +0900
commitd287de855f97c56ca7146ff627e652bd7cd64f3f (patch)
treea3dbeb4937853cf1e81dca65c97c2dbbda549129 /drivers/devfreq
parente09651fcc295a7dc802f38d9494f5b860dd90bca (diff)
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>
Diffstat (limited to 'drivers/devfreq')
-rw-r--r--drivers/devfreq/devfreq.c32
1 files changed, 32 insertions, 0 deletions
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),