PM / devfreq: Add common sysfs interfaces (9005b650) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-class-devfreq

0 → 100644

+44 −0

Original line number	Diff line number	Diff line
		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.

drivers/devfreq/devfreq.c

+69 −0

Original line number	Diff line number	Diff line
		@@ -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);

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