Commit e552bbaf authored by Jonghwa Lee's avatar Jonghwa Lee Committed by MyungJoo Ham
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PM / devfreq: Add sysfs node for representing frequency transition information. 



This patch adds sysfs node which can be used to get information of frequency
transition. It represents transition table which contains total number of transition of
each freqeuncy state and time spent. It is inspired CPUFREQ's status driver.

Signed-off-by: default avatarJonghwa Lee <jonghwa3.lee@samsung.com>
[Added Documentation/ABI entry, updated kernel-doc, and resolved merge conflict]
Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
parent d287de85

Documentation/ABI/testing/sysfs-class-devfreq

+11 −0
Original line number Diff line number Diff line
@@ -44,6 +44,17 @@ Description: 
		(/sys/class/devfreq/.../central_polling is 0), this value

		may be useless.



What:		/sys/class/devfreq/.../trans_stat

Date:		October 2012

Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>

Descrtiption:

		This ABI shows the statistics of devfreq behavior on a

		specific device. It shows the time spent in each state and

		the number of transitions between states.

		In order to activate this ABI, the devfreq target device

		driver should provide the list of available frequencies

		with its profile.



What:		/sys/class/devfreq/.../userspace/set_freq

Date:		September 2011

Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>

drivers/devfreq/devfreq.c

+101 −0
Original line number Diff line number Diff line
@@ -66,6 +66,51 @@ static struct devfreq *find_device_devfreq(struct device *dev) 
	return ERR_PTR(-ENODEV);

}



/**

 * devfreq_get_freq_level() - Lookup freq_table for the frequency

 * @devfreq:	the devfreq instance

 * @freq:	the target frequency

 */

static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)

{

	int lev;



	for (lev = 0; lev < devfreq->profile->max_state; lev++)

		if (freq == devfreq->profile->freq_table[lev])

			return lev;



	return -EINVAL;

}



/**

 * devfreq_update_status() - Update statistics of devfreq behavior

 * @devfreq:	the devfreq instance

 * @freq:	the update target frequency

 */

static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)

{

	int lev, prev_lev;

	unsigned long cur_time;



	lev = devfreq_get_freq_level(devfreq, freq);

	if (lev < 0)

		return lev;



	cur_time = jiffies;

	devfreq->time_in_state[lev] +=

			 cur_time - devfreq->last_stat_updated;

	if (freq != devfreq->previous_freq) {

		prev_lev = devfreq_get_freq_level(devfreq,

						devfreq->previous_freq);

		devfreq->trans_table[(prev_lev *

				devfreq->profile->max_state) + lev]++;

		devfreq->total_trans++;

	}

	devfreq->last_stat_updated = cur_time;



	return 0;

}



/* Load monitoring helper functions for governors use */



/**
@@ -112,6 +157,11 @@ int update_devfreq(struct devfreq *devfreq) 
	if (err)

		return err;



	if (devfreq->profile->freq_table)

		if (devfreq_update_status(devfreq, freq))

			dev_err(&devfreq->dev,

				"Couldn't update frequency transition information.\n");



	devfreq->previous_freq = freq;

	return err;

}
@@ -378,6 +428,15 @@ struct devfreq *devfreq_add_device(struct device *dev, 
	devfreq->data = data;

	devfreq->nb.notifier_call = devfreq_notifier_call;



	devfreq->trans_table =	devm_kzalloc(dev, sizeof(unsigned int) *

						devfreq->profile->max_state *

						devfreq->profile->max_state,

						GFP_KERNEL);

	devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *

						devfreq->profile->max_state,

						GFP_KERNEL);

	devfreq->last_stat_updated = jiffies;



	dev_set_name(&devfreq->dev, dev_name(dev));

	err = device_register(&devfreq->dev);

	if (err) {
@@ -601,6 +660,47 @@ static ssize_t show_available_freqs(struct device *d, 
	return count;

}



static ssize_t show_trans_table(struct device *dev, struct device_attribute *attr,

				char *buf)

{

	struct devfreq *devfreq = to_devfreq(dev);

	ssize_t len;

	int i, j, err;

	unsigned int max_state = devfreq->profile->max_state;



	err = devfreq_update_status(devfreq, devfreq->previous_freq);

	if (err)

		return 0;



	len = sprintf(buf, "   From  :   To\n");

	len += sprintf(buf + len, "         :");

	for (i = 0; i < max_state; i++)

		len += sprintf(buf + len, "%8u",

				devfreq->profile->freq_table[i]);



	len += sprintf(buf + len, "   time(ms)\n");



	for (i = 0; i < max_state; i++) {

		if (devfreq->profile->freq_table[i]

					== devfreq->previous_freq) {

			len += sprintf(buf + len, "*");

		} else {

			len += sprintf(buf + len, " ");

		}

		len += sprintf(buf + len, "%8u:",

				devfreq->profile->freq_table[i]);

		for (j = 0; j < max_state; j++)

			len += sprintf(buf + len, "%8u",

				devfreq->trans_table[(i * max_state) + j]);

		len += sprintf(buf + len, "%10u\n",

			jiffies_to_msecs(devfreq->time_in_state[i]));

	}



	len += sprintf(buf + len, "Total transition : %u\n",

					devfreq->total_trans);

	return len;

}



static struct device_attribute devfreq_attrs[] = {

	__ATTR(governor, S_IRUGO, show_governor, NULL),

	__ATTR(cur_freq, S_IRUGO, show_freq, NULL),
@@ -610,6 +710,7 @@ static struct device_attribute devfreq_attrs[] = { 
	       store_polling_interval),

	__ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),

	__ATTR(max_freq, S_IRUGO | S_IWUSR, show_max_freq, store_max_freq),

	__ATTR(trans_stat, S_IRUGO, show_trans_table, NULL),

	{ },

};

include/linux/devfreq.h

+15 −0
Original line number Diff line number Diff line
@@ -73,6 +73,8 @@ struct devfreq_dev_status { 
 *			from devfreq_remove_device() call. If the user

 *			has registered devfreq->nb at a notifier-head,

 *			this is the time to unregister it.

 * @freq_table:	Optional list of frequencies to support statistics.

 * @max_state:	The size of freq_table.

 */

struct devfreq_dev_profile {

	unsigned long initial_freq;
@@ -83,6 +85,9 @@ struct devfreq_dev_profile { 
			      struct devfreq_dev_status *stat);

	int (*get_cur_freq)(struct device *dev, unsigned long *freq);

	void (*exit)(struct device *dev);



	unsigned int *freq_table;

	unsigned int max_state;

};



/**
@@ -127,6 +132,10 @@ struct devfreq_governor { 
 * @min_freq:	Limit minimum frequency requested by user (0: none)

 * @max_freq:	Limit maximum frequency requested by user (0: none)

 * @stop_polling:	 devfreq polling status of a device.

 * @total_trans:	Number of devfreq transitions

 * @trans_table:	Statistics of devfreq transitions

 * @time_in_state:	Statistics of devfreq states

 * @last_stat_updated:	The last time stat updated

 *

 * This structure stores the devfreq information for a give device.

 *
@@ -153,6 +162,12 @@ struct devfreq { 
	unsigned long min_freq;

	unsigned long max_freq;

	bool stop_polling;



	/* information for device freqeuncy transition */

	unsigned int total_trans;

	unsigned int *trans_table;

	unsigned long *time_in_state;

	unsigned long last_stat_updated;

};



#if defined(CONFIG_PM_DEVFREQ)

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