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PM / devfreq: Add common sysfs interfaces

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Device specific sysfs interface /sys/devices/.../power/devfreq_*
- governor	R: name of governor
- cur_freq	R: current frequency
- polling_interval	R: polling interval in ms given with devfreq profile
			W: update polling interval.
- central_polling	R: 1 if polling is managed by devfreq framework

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mike Turquette <mturquette@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
--
 Documentation/ABI/testing/sysfs-class-devfreq |   44 ++++++++++++++++
 drivers/devfreq/devfreq.c                     |   69 ++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-devfreq
This commit is contained in:
MyungJoo Ham 2011-10-02 00:19:28 +02:00 committed by Rafael J. Wysocki
parent a3c98b8b2e
commit 9005b65099
2 changed files with 113 additions and 0 deletions
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44
Documentation/ABI/testing/sysfs-class-devfreq Normal file
View file

@ -0,0 +1,44 @@
What: /sys/class/devfreq/.../
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
Provide a place in sysfs for the devfreq objects.
This allows accessing various devfreq specific variables.
The name of devfreq object denoted as ... is same as the
name of device using devfreq.
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
governor used by the corresponding devfreq object.
What: /sys/class/devfreq/.../cur_freq
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../cur_freq shows the current
frequency of the corresponding devfreq object.
What: /sys/class/devfreq/.../central_polling
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../central_polling shows whether
the devfreq ojbect is using devfreq-provided central
polling mechanism or not.
What: /sys/class/devfreq/.../polling_interval
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../polling_interval shows and sets
the requested polling interval of the corresponding devfreq
object. The values are represented in ms. If the value is
less than 1 jiffy, it is considered to be 0, which means
no polling. This value is meaningless if the governor is
not polling; thus. If the governor is not using
devfreq-provided central polling
(/sys/class/devfreq/.../central_polling is 0), this value
may be useless.

69
drivers/devfreq/devfreq.c
View file

@ -437,6 +437,74 @@ int devfreq_remove_device(struct devfreq *devfreq)
return 0;
}
static ssize_t show_governor(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
}
static ssize_t show_freq(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
}
static ssize_t show_polling_interval(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
}
static ssize_t store_polling_interval(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct devfreq *df = to_devfreq(dev);
unsigned int value;
int ret;
ret = sscanf(buf, "%u", &value);
if (ret != 1)
goto out;
mutex_lock(&df->lock);
df->profile->polling_ms = value;
df->next_polling = df->polling_jiffies
= msecs_to_jiffies(value);
mutex_unlock(&df->lock);
ret = count;
if (df->governor->no_central_polling)
goto out;
mutex_lock(&devfreq_list_lock);
if (df->next_polling > 0 && !polling) {
polling = true;
queue_delayed_work(devfreq_wq, &devfreq_work,
df->next_polling);
}
mutex_unlock(&devfreq_list_lock);
out:
return ret;
}
static ssize_t show_central_polling(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n",
!to_devfreq(dev)->governor->no_central_polling);
}
static struct device_attribute devfreq_attrs[] = {
__ATTR(governor, S_IRUGO, show_governor, NULL),
__ATTR(cur_freq, S_IRUGO, show_freq, NULL),
__ATTR(central_polling, S_IRUGO, show_central_polling, NULL),
__ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
store_polling_interval),
{ },
};
/**
* devfreq_start_polling() - Initialize data structure for devfreq framework and
* start polling registered devfreq devices.
@ -461,6 +529,7 @@ static int __init devfreq_init(void)
pr_err("%s: couldn't create class\n", __FILE__);
return PTR_ERR(devfreq_class);
}
devfreq_class->dev_attrs = devfreq_attrs;
return 0;
}
subsys_initcall(devfreq_init);