Merge "Merge branch 'cpufreq-upstream' into msm-3.10"

		to learn how to control the knobs.

What:		/sys/devices/system/cpu/cpu#/cpufreq/freqdomain_cpus

Date:		June 2013

Contact:	cpufreq@vger.kernel.org

Description:	Discover CPUs in the same CPU frequency coordination domain

		freqdomain_cpus is the list of CPUs (online+offline) that share

		the same clock/freq domain (possibly at the hardware level).

		That information may be hidden from the cpufreq core and the

		value of related_cpus may be different from freqdomain_cpus. This

		attribute is useful for user space DVFS controllers to get better

		power/performance results for platforms using acpi-cpufreq.

		This file is only present if the acpi-cpufreq driver is in use.

What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}

Date:		August 2008

KernelVersion:	2.6.27

DEBUG_INFO

FRAME_POINTER

CPU_FREQ

CPU_FREQ_TABLE

CPU_FREQ_DEFAULT_GOV_ONDEMAND

CPU_FREQ_GOV_ONDEMAND

CRC_CCITT

1.1  Initialization

1.2  Per-CPU Initialization

1.3  verify

1.4  target or setpolicy?

1.5  target

1.4  target/target_index or setpolicy?

1.5  target/target_index

1.6  setpolicy

2.   Frequency Table Helpers

cpufreq_driver.name -		The name of this driver.

cpufreq_driver.owner -		THIS_MODULE;

cpufreq_driver.init -		A pointer to the per-CPU initialization 

				function.

cpufreq_driver.verify -		A pointer to a "verification" function.

cpufreq_driver.setpolicy _or_ 

cpufreq_driver.target -		See below on the differences.

cpufreq_driver.target/

target_index		-	See below on the differences.

And optionally

				which is called with interrupts disabled

				and _before_ the pre-suspend frequency

				and/or policy is restored by a call to

				->target or ->setpolicy.

				->target/target_index or ->setpolicy.

cpufreq_driver.attr -		A pointer to a NULL-terminated list of

				"struct freq_attr" which allow to

				this CPU. A few moments later,

				cpufreq_driver.verify and either

				cpufreq_driver.setpolicy or

				cpufreq_driver.target is called with

				these values.

				cpufreq_driver.target/target_index is called

				with these values.

For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the

frequency table helpers might be helpful. See the section 2 for more information

policy->max first, and only if this is no solution, decrease policy->min.

1.4 target or setpolicy?

1.4 target/target_index or setpolicy?

----------------------------

Most cpufreq drivers or even most cpu frequency scaling algorithms 

only allow the CPU to be set to one frequency. For these, you use the

->target call.

->target/target_index call.

Some cpufreq-capable processors switch the frequency between certain

limits on their own. These shall use the ->setpolicy call

1.4. target

1.4. target/target_index

-------------

The target_index call has two arguments: struct cpufreq_policy *policy,

and unsigned int index (into the exposed frequency table).

The CPUfreq driver must set the new frequency when called here. The

actual frequency must be determined by freq_table[index].frequency.

Deprecated:

----------

The target call has three arguments: struct cpufreq_policy *policy,

unsigned int target_frequency, unsigned int relation.

frequencies, a "frequency table" with some functions might assist in

some work of the processor driver. Such a "frequency table" consists

of an array of struct cpufreq_frequency_table entries, with any value in

"index" you want to use, and the corresponding frequency in

"driver_data" you want to use, and the corresponding frequency in

"frequency". At the end of the table, you need to add a

cpufreq_frequency_table entry with frequency set to CPUFREQ_TABLE_END. And

if you want to skip one entry in the table, set the frequency to 

is the corresponding frequency table helper for the ->target

stage. Just pass the values to this function, and the unsigned int

index returns the number of the frequency table entry which contains

the frequency the CPU shall be set to. PLEASE NOTE: This is not the

"index" which is in this cpufreq_table_entry.index, but instead

cpufreq_table[index]. So, the new frequency is

cpufreq_table[index].frequency, and the value you stored into the

frequency table "index" field is

cpufreq_table[index].index.

the frequency the CPU shall be set to.

cpu frequency scaling algorithms only offer the CPU to be set to one

frequency. In order to offer dynamic frequency scaling, the cpufreq

core must be able to tell these drivers of a "target frequency". So

these specific drivers will be transformed to offer a "->target"

these specific drivers will be transformed to offer a "->target/target_index"

call instead of the existing "->setpolicy" call. For "longrun", all

stays the same, though.

		    /			       the limits of policy->{min,max}

		   /			            \

		  /				     \

	Using the ->setpolicy call,		 Using the ->target call,

	Using the ->setpolicy call,		 Using the ->target/target_index call,

	    the limits and the			  the frequency closest

	     "policy" is set.			  to target_freq is set.

						  It is assured that it

OPP library provides a set of helper functions to organize and query the OPP

information. The library is located in drivers/base/power/opp.c and the header

is located in include/linux/opp.h. OPP library can be enabled by enabling

is located in include/linux/pm_opp.h. OPP library can be enabled by enabling

CONFIG_PM_OPP from power management menuconfig menu. OPP library depends on

CONFIG_PM as certain SoCs such as Texas Instrument's OMAP framework allows to

optionally boot at a certain OPP without needing cpufreq.

OPP library facilitates this concept in it's implementation. The following

operational functions operate only on available opps:

opp_find_freq_{ceil, floor}, opp_get_voltage, opp_get_freq, opp_get_opp_count

and opp_init_cpufreq_table

opp_find_freq_{ceil, floor}, dev_pm_opp_get_voltage, dev_pm_opp_get_freq, dev_pm_opp_get_opp_count

and dev_pm_opp_init_cpufreq_table

opp_find_freq_exact is meant to be used to find the opp pointer which can then

be used for opp_enable/disable functions to make an opp available as required.

dev_pm_opp_find_freq_exact is meant to be used to find the opp pointer which can then

be used for dev_pm_opp_enable/disable functions to make an opp available as required.

WARNING: Users of OPP library should refresh their availability count using

get_opp_count if opp_enable/disable functions are invoked for a device, the

get_opp_count if dev_pm_opp_enable/disable functions are invoked for a device, the

exact mechanism to trigger these or the notification mechanism to other

dependent subsystems such as cpufreq are left to the discretion of the SoC

specific framework which uses the OPP library. Similar care needs to be taken

opp_get_{voltage, freq, opp_count} fall into this category.

opp_{add,enable,disable} are updaters which use mutex and implement it's own

RCU locking mechanisms. opp_init_cpufreq_table acts as an updater and uses

RCU locking mechanisms. dev_pm_opp_init_cpufreq_table acts as an updater and uses

mutex to implment RCU updater strategy. These functions should *NOT* be called

under RCU locks and other contexts that prevent blocking functions in RCU or

mutex operations from working.

2. Initial OPP List Registration

================================

The SoC implementation calls opp_add function iteratively to add OPPs per

The SoC implementation calls dev_pm_opp_add function iteratively to add OPPs per

device. It is expected that the SoC framework will register the OPP entries

optimally- typical numbers range to be less than 5. The list generated by

registering the OPPs is maintained by OPP library throughout the device

operation. The SoC framework can subsequently control the availability of the

OPPs dynamically using the opp_enable / disable functions.

OPPs dynamically using the dev_pm_opp_enable / disable functions.

opp_add - Add a new OPP for a specific domain represented by the device pointer.

dev_pm_opp_add - Add a new OPP for a specific domain represented by the device pointer.

	The OPP is defined using the frequency and voltage. Once added, the OPP

	is assumed to be available and control of it's availability can be done

	with the opp_enable/disable functions. OPP library internally stores

	with the dev_pm_opp_enable/disable functions. OPP library internally stores

	and manages this information in the opp struct. This function may be

	used by SoC framework to define a optimal list as per the demands of

	SoC usage environment.

	 soc_pm_init()

	 {

		/* Do things */

		r = opp_add(mpu_dev, 1000000, 900000);

		r = dev_pm_opp_add(mpu_dev, 1000000, 900000);

		if (!r) {

			pr_err("%s: unable to register mpu opp(%d)\n", r);

			goto no_cpufreq;

found, else returns error. These errors are expected to be handled by standard

error checks such as IS_ERR() and appropriate actions taken by the caller.

opp_find_freq_exact - Search for an OPP based on an *exact* frequency and

dev_pm_opp_find_freq_exact - Search for an OPP based on an *exact* frequency and

	availability. This function is especially useful to enable an OPP which

	is not available by default.

	Example: In a case when SoC framework detects a situation where a

	higher frequency could be made available, it can use this function to

	find the OPP prior to call the opp_enable to actually make it available.

	find the OPP prior to call the dev_pm_opp_enable to actually make it available.

	 rcu_read_lock();

	 opp = opp_find_freq_exact(dev, 1000000000, false);

	 opp = dev_pm_opp_find_freq_exact(dev, 1000000000, false);

	 rcu_read_unlock();

	 /* dont operate on the pointer.. just do a sanity check.. */

	 if (IS_ERR(opp)) {

		pr_err("frequency not disabled!\n");

		/* trigger appropriate actions.. */

	 } else {

		opp_enable(dev,1000000000);

		dev_pm_opp_enable(dev,1000000000);

	 }

	NOTE: This is the only search function that operates on OPPs which are

	not available.

opp_find_freq_floor - Search for an available OPP which is *at most* the

dev_pm_opp_find_freq_floor - Search for an available OPP which is *at most* the

	provided frequency. This function is useful while searching for a lesser

	match OR operating on OPP information in the order of decreasing

	frequency.

	Example: To find the highest opp for a device:

	 freq = ULONG_MAX;

	 rcu_read_lock();

	 opp_find_freq_floor(dev, &freq);

	 dev_pm_opp_find_freq_floor(dev, &freq);

	 rcu_read_unlock();

opp_find_freq_ceil - Search for an available OPP which is *at least* the

dev_pm_opp_find_freq_ceil - Search for an available OPP which is *at least* the

	provided frequency. This function is useful while searching for a

	higher match OR operating on OPP information in the order of increasing

	frequency.

	Example 1: To find the lowest opp for a device:

	 freq = 0;

	 rcu_read_lock();

	 opp_find_freq_ceil(dev, &freq);

	 dev_pm_opp_find_freq_ceil(dev, &freq);

	 rcu_read_unlock();

	Example 2: A simplified implementation of a SoC cpufreq_driver->target:

	 soc_cpufreq_target(..)

		/* Do stuff like policy checks etc. */

		/* Find the best frequency match for the req */

		rcu_read_lock();

		opp = opp_find_freq_ceil(dev, &freq);

		opp = dev_pm_opp_find_freq_ceil(dev, &freq);

		rcu_read_unlock();

		if (!IS_ERR(opp))

			soc_switch_to_freq_voltage(freq);

WARNING: Do not use these functions in interrupt context.

opp_enable - Make a OPP available for operation.

dev_pm_opp_enable - Make a OPP available for operation.

	Example: Lets say that 1GHz OPP is to be made available only if the

	SoC temperature is lower than a certain threshold. The SoC framework

	implementation might choose to do something as follows:

	 if (cur_temp < temp_low_thresh) {

		/* Enable 1GHz if it was disabled */

		rcu_read_lock();

		opp = opp_find_freq_exact(dev, 1000000000, false);

		opp = dev_pm_opp_find_freq_exact(dev, 1000000000, false);

		rcu_read_unlock();

		/* just error check */

		if (!IS_ERR(opp))

			ret = opp_enable(dev, 1000000000);

			ret = dev_pm_opp_enable(dev, 1000000000);

		else

			goto try_something_else;

	 }

opp_disable - Make an OPP to be not available for operation

dev_pm_opp_disable - Make an OPP to be not available for operation

	Example: Lets say that 1GHz OPP is to be disabled if the temperature

	exceeds a threshold value. The SoC framework implementation might

	choose to do something as follows:

	 if (cur_temp > temp_high_thresh) {

		/* Disable 1GHz if it was enabled */

		rcu_read_lock();

		opp = opp_find_freq_exact(dev, 1000000000, true);

		opp = dev_pm_opp_find_freq_exact(dev, 1000000000, true);

		rcu_read_unlock();

		/* just error check */

		if (!IS_ERR(opp))

			ret = opp_disable(dev, 1000000000);

			ret = dev_pm_opp_disable(dev, 1000000000);

		else

			goto try_something_else;

	 }

retrieved using the search functions, the following functions can be used by SoC

framework to retrieve the information represented inside the OPP layer.

opp_get_voltage - Retrieve the voltage represented by the opp pointer.

dev_pm_opp_get_voltage - Retrieve the voltage represented by the opp pointer.

	Example: At a cpufreq transition to a different frequency, SoC

	framework requires to set the voltage represented by the OPP using

	the regulator framework to the Power Management chip providing the

	 {

		/* do things */

		rcu_read_lock();

		opp = opp_find_freq_ceil(dev, &freq);

		v = opp_get_voltage(opp);

		opp = dev_pm_opp_find_freq_ceil(dev, &freq);

		v = dev_pm_opp_get_voltage(opp);

		rcu_read_unlock();

		if (v)

			regulator_set_voltage(.., v);

		/* do other things */

	 }

opp_get_freq - Retrieve the freq represented by the opp pointer.

dev_pm_opp_get_freq - Retrieve the freq represented by the opp pointer.

	Example: Lets say the SoC framework uses a couple of helper functions

	we could pass opp pointers instead of doing additional parameters to

	handle quiet a bit of data parameters.

		/* do things.. */

		 max_freq = ULONG_MAX;

		 rcu_read_lock();

		 max_opp = opp_find_freq_floor(dev,&max_freq);

		 requested_opp = opp_find_freq_ceil(dev,&freq);

		 max_opp = dev_pm_opp_find_freq_floor(dev,&max_freq);

		 requested_opp = dev_pm_opp_find_freq_ceil(dev,&freq);

		 if (!IS_ERR(max_opp) && !IS_ERR(requested_opp))

			r = soc_test_validity(max_opp, requested_opp);

		 rcu_read_unlock();

	 }

	 soc_test_validity(..)

	 {

		 if(opp_get_voltage(max_opp) < opp_get_voltage(requested_opp))

		 if(dev_pm_opp_get_voltage(max_opp) < dev_pm_opp_get_voltage(requested_opp))

			 return -EINVAL;

		 if(opp_get_freq(max_opp) < opp_get_freq(requested_opp))

		 if(dev_pm_opp_get_freq(max_opp) < dev_pm_opp_get_freq(requested_opp))

			 return -EINVAL;

		/* do things.. */

	 }

opp_get_opp_count - Retrieve the number of available opps for a device

dev_pm_opp_get_opp_count - Retrieve the number of available opps for a device

	Example: Lets say a co-processor in the SoC needs to know the available

	frequencies in a table, the main processor can notify as following:

	 soc_notify_coproc_available_frequencies()

	 {

		/* Do things */

		rcu_read_lock();

		num_available = opp_get_opp_count(dev);

		num_available = dev_pm_opp_get_opp_count(dev);

		speeds = kzalloc(sizeof(u32) * num_available, GFP_KERNEL);

		/* populate the table in increasing order */

		freq = 0;

		while (!IS_ERR(opp = opp_find_freq_ceil(dev, &freq))) {

		while (!IS_ERR(opp = dev_pm_opp_find_freq_ceil(dev, &freq))) {

			speeds[i] = freq;

			freq++;

			i++;

6. Cpufreq Table Generation

===========================

opp_init_cpufreq_table - cpufreq framework typically is initialized with

dev_pm_opp_init_cpufreq_table - cpufreq framework typically is initialized with

	cpufreq_frequency_table_cpuinfo which is provided with the list of

	frequencies that are available for operation. This function provides

	a ready to use conversion routine to translate the OPP layer's internal

	 soc_pm_init()

	 {

		/* Do things */

		r = opp_init_cpufreq_table(dev, &freq_table);

		r = dev_pm_opp_init_cpufreq_table(dev, &freq_table);

		if (!r)

			cpufreq_frequency_table_cpuinfo(policy, freq_table);

		/* Do other things */

	addition to CONFIG_PM as power management feature is required to

	dynamically scale voltage and frequency in a system.

opp_free_cpufreq_table - Free up the table allocated by opp_init_cpufreq_table

dev_pm_opp_free_cpufreq_table - Free up the table allocated by dev_pm_opp_init_cpufreq_table

7. Data Structures

==================

	identifier for OPP in the interactions with OPP layer.

	WARNING: The struct opp pointer should not be parsed or modified by the

	users. The defaults of for an instance is populated by opp_add, but the

	availability of the OPP can be modified by opp_enable/disable functions.

	users. The defaults of for an instance is populated by dev_pm_opp_add, but the

	availability of the OPP can be modified by dev_pm_opp_enable/disable functions.

struct device - This is used to identify a domain to the OPP layer. The

	nature of the device and it's implementation is left to the user of

following:

Initialization / modification:

            +-----+        /- opp_enable

opp_add --> | opp | <-------

  |         +-----+        \- opp_disable

            +-----+        /- dev_pm_opp_enable

dev_pm_opp_add --> | opp | <-------

  |         +-----+        \- dev_pm_opp_disable

  \-------> domain_info(device)

Search functions:

             /-- opp_find_freq_ceil  ---\   +-----+

domain_info<---- opp_find_freq_exact -----> | opp |

             \-- opp_find_freq_floor ---/   +-----+

             /-- dev_pm_opp_find_freq_ceil  ---\   +-----+

domain_info<---- dev_pm_opp_find_freq_exact -----> | opp |

             \-- dev_pm_opp_find_freq_floor ---/   +-----+

Retrieval functions:

+-----+     /- opp_get_voltage

+-----+     /- dev_pm_opp_get_voltage

| opp | <---

+-----+     \- opp_get_freq

+-----+     \- dev_pm_opp_get_freq

domain_info <- opp_get_opp_count

domain_info <- dev_pm_opp_get_opp_count