/*
* linux/drivers/thermal/cpu_cooling.c
*
* Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
* Copyright (C) 2012 Amit Daniel <amit.kachhap@linaro.org>
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#include <linux/module.h>
#include <linux/thermal.h>
#include <linux/cpufreq.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/cpu_cooling.h>
/**
* struct cpufreq_cooling_device - data for cooling device with cpufreq
* @id: unique integer value corresponding to each cpufreq_cooling_device
* registered.
* @cool_dev: thermal_cooling_device pointer to keep track of the
* registered cooling device.
* @cpufreq_state: integer value representing the current state of cpufreq
* cooling devices.
* @cpufreq_val: integer value representing the absolute value of the clipped
* frequency.
* @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
*
* This structure is required for keeping information of each
* cpufreq_cooling_device registered. In order to prevent corruption of this a
* mutex lock cooling_cpufreq_lock is used.
*/
struct cpufreq_cooling_device {
int id;
struct thermal_cooling_device *cool_dev;
unsigned int cpufreq_state;
unsigned int cpufreq_val;
struct cpumask allowed_cpus;
};
static DEFINE_IDR(cpufreq_idr);
static DEFINE_MUTEX(cooling_cpufreq_lock);
static unsigned int cpufreq_dev_count;
/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
#define NOTIFY_INVALID NULL
static struct cpufreq_cooling_device *notify_device;
/**
* get_idr - function to get a unique id.
* @idr: struct idr * handle used to create a id.
* @id: int * value generated by this function.
*
* This function will populate @id with an unique
* id, using the idr API.
*
* Return: 0 on success, an error code on failure.
*/
static int get_idr(struct idr *idr, int *id)
{
int ret;
mutex_lock(&cooling_cpufreq_lock);
ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
mutex_unlock(&cooling_cpufreq_lock);
if (unlikely(ret < 0))
return ret;
*id = ret;
return 0;
}
/**
* release_idr - function to free the unique id.
* @idr: struct idr * handle used for creating the id.
* @id: int value representing the unique id.
*/
static void release_idr(struct idr *idr, int id)
{
mutex_lock(&cooling_cpufreq_lock);
idr_remove(idr, id);
mutex_unlock(&cooling_cpufreq_lock);
}
/* Below code defines functions to be used for cpufreq as cooling device */
/**
* is_cpufreq_valid - function to check frequency transitioning capability.
* @cpu: cpu for which check is needed.
*
* This function will check the current state of the system if
* it is capable of changing the frequency for a given @cpu.
*
* Return: 0 if the system is not currently capable of changing
* the frequency of given cpu. !0 in case the frequency is changeable.
*/
static int is_cpufreq_valid(int cpu)
{
struct cpufreq_policy policy;
return !cpufreq_get_policy(&policy, cpu);
}
enum cpufreq_cooling_property {
GET_LEVEL,
GET_FREQ,
GET_MAXL,
};
/**
* get_property - fetch a property of interest for a give cpu.
* @cpu: cpu for which the property is required
* @input: query parameter
* @output: query return
* @property: type of query (frequency, level, max level)
*
* This is the common function to
* 1. get maximum cpu cooling states
* 2. translate frequency to cooling state
* 3. translate cooling state to frequency
* Note that the code may be not in good shape
* but it is written in this way in order to:
* a) reduce duplicate code as most of the code can be shared.
* b) make sure the logic is consistent when translating between
* cooling states and frequencies.
*
* Return: 0 on success, -EINVAL when invalid parameters are passed.
*/
static int get_property(unsigned int cpu, unsigned long input,
unsigned int *output,
enum cpufreq_cooling_property property)
{
int i, j;
unsigned long max_level = 0, level = 0;
unsigned int freq = CPUFREQ_ENTRY_INVALID;
int descend = -1;
struct cpufreq_frequency_table *table =
cpufreq_frequency_get_table(cpu);
if (!output)
return -EINVAL;
if (!table)
return -EINVAL;
for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
/* ignore invalid entries */
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;
/* ignore duplicate entry */
if (freq == table[i].frequency)
continue;
/* get the frequency order */
if (freq != CPUFREQ_ENTRY_INVALID && descend != -1)
descend = !!(freq > table[i].frequency);
freq = table[i].frequency;
max_level++;
}
/* get max level */
if (property == GET_MAXL) {
*output = (unsigned int)max_level;
return 0;
}
if (property == GET_FREQ)
level = descend ? input : (max_level - input - 1);
for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
/* ignore invalid entry */
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;
/* ignore duplicate entry */
if (freq == table[i].frequency)
continue;
/* now we have a valid frequency entry */
freq = table[i].frequency;
if (property == GET_LEVEL && (unsigned int)input == freq) {
/* get level by frequency */
*output = descend ? j : (max_level - j - 1);
return 0;
}
if (property == GET_FREQ && level == j) {
/* get frequency by level */
*output = freq;
return 0;
}
j++;
}
return -EINVAL;
}
/**
* cpufreq_cooling_get_level - for a give cpu, return the cooling level.
* @cpu: cpu for which the level is required
* @freq: the frequency of interest
*
* This function will match the cooling level corresponding to the
* requested @freq and return it.
*
* Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
* otherwise.
*/
unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
{
unsigned int val;
if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
return THERMAL_CSTATE_INVALID;
return (unsigned long)val;
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
/**
* get_cpu_frequency - get the absolute value of frequency from level.
* @cpu: cpu for which frequency is fetched.
* @level: cooling level
*
* This function matches cooling level with frequency. Based on a cooling level
* of frequency, equals cooling state of cpu cooling device, it will return
* the corresponding frequency.
* e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
*
* Return: 0 on error, the corresponding frequency otherwise.
*/
static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
{
int ret = 0;
unsigned int freq;
ret = get_property(cpu, level, &freq, GET_FREQ);
if (ret)
return 0;
return freq;
}
/**
* cpufreq_apply_cooling - function to apply frequency clipping.
* @cpufreq_device: cpufreq_cooling_device pointer containing frequency
* clipping data.
* @cooling_state: value of the cooling state.
*
* Function used to make sure the cpufreq layer is aware of current thermal
* limits. The limits are applied by updating the cpufreq policy.
*
* Return: 0 on success, an error code otherwise (-EINVAL in case wrong
* cooling state).
*/
static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
unsigned long cooling_state)
{
unsigned int cpuid, clip_freq;
struct cpumask *mask = &cpufreq_device->allowed_cpus;
unsigned int cpu = cpumask_any(mask);
/* Check if the old cooling action is same as new cooling action */
if (cpufreq_device->cpufreq_state == cooling_state)
return 0;
clip_freq = get_cpu_frequency(cpu, cooling_state);
if (!clip_freq)
return -EINVAL;
cpufreq_device->cpufreq_state = cooling_state;
cpufreq_device->cpufreq_val = clip_freq;
notify_device = cpufreq_device;
for_each_cpu(cpuid, mask) {
if (is_cpufreq_valid(cpuid))
cpufreq_update_policy(cpuid);
}
notify_device = NOTIFY_INVALID;
return 0;
}
/**
* cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
* @nb: struct notifier_block * with callback info.
* @event: value showing cpufreq event for which this function invoked.
* @data: callback-specific data
*
* Callback to highjack the notification on cpufreq policy transition.
* Every time there is a change in policy, we will intercept and
* update the cpufreq policy with thermal constraints.
*
* Return: 0 (success)
*/
static int cpufreq_thermal_notifier(struct notifier_block *nb,
unsigned long event, void *data)
{
struct cpufreq_policy *policy = data;
unsigned long max_freq = 0;
if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
return 0;
if (cpumask_test_cpu(policy->cpu, ¬ify_device->allowed_cpus))
max_freq = notify_device->cpufreq_val;
/* Never exceed user_policy.max */
if (max_freq > policy->user_policy.max)
max_freq = policy->user_policy.max;
if (policy->max != max_freq)
cpufreq_verify_within_limits(policy, 0, max_freq);
return 0;
}
/* cpufreq cooling device callback functions are defined below */
/**
* cpufreq_get_max_state - callback function to get the max cooling state.
* @cdev: thermal cooling device pointer.
* @state: fill this variable with the max cooling state.
*
* Callback for the thermal cooling device to return the cpufreq
* max cooling state.
*
* Return: 0 on success, an error code otherwise.
*/
static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
struct cpumask *mask = &cpufreq_device->allowed_cpus;
unsigned int cpu;
unsigned int count = 0;
int ret;
cpu = cpumask_any(mask);
ret = get_property(cpu, 0, &count, GET_MAXL);
if (count > 0)
*state = count;
return ret;
}
/**
* cpufreq_get_cur_state - callback function to get the current cooling state.
* @cdev: thermal cooling device pointer.
* @state: fill this variable with the current cooling state.
*
* Callback for the thermal cooling device to return the cpufreq
* current cooling state.
*
* Return: 0 on success, an error code otherwise.
*/
static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
*state = cpufreq_device->cpufreq_state;
return 0;
}
/**
* cpufreq_set_cur_state - callback function to set the current cooling state.
* @cdev: thermal cooling device pointer.
* @state: set this variable to the current cooling state.
*
* Callback for the thermal cooling device to change the cpufreq
* current cooling state.
*
* Return: 0 on success, an error code otherwise.
*/
static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
unsigned long state)
{
struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
return cpufreq_apply_cooling(cpufreq_device, state);
}
/* Bind cpufreq callbacks to thermal cooling device ops */
static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
.get_max_state = cpufreq_get_max_state,
.get_cur_state = cpufreq_get_cur_state,
.set_cur_state = cpufreq_set_cur_state,
};
/* Notifier for cpufreq policy change */
static struct notifier_block thermal_cpufreq_notifier_block = {
.notifier_call = cpufreq_thermal_notifier,
};
/**
* cpufreq_cooling_register - function to create cpufreq cooling device.
* @clip_cpus: cpumask of cpus where the frequency constraints will happen.
*
* This interface function registers the cpufreq cooling device with the name
* "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
* cooling devices.
*
* Return: a valid struct thermal_cooling_device pointer on success,
* on failure, it returns a corresponding ERR_PTR().
*/
struct thermal_cooling_device *
cpufreq_cooling_register(const struct cpumask *clip_cpus)
{
struct thermal_cooling_device *cool_dev;
struct cpufreq_cooling_device *cpufreq_dev = NULL;
unsigned int min = 0, max = 0;
char dev_name[THERMAL_NAME_LENGTH];
int ret = 0, i;
struct cpufreq_policy policy;
/* Verify that all the clip cpus have same freq_min, freq_max limit */
for_each_cpu(i, clip_cpus) {
/* continue if cpufreq policy not found and not return error */
if (!cpufreq_get_policy(&policy, i))
continue;
if (min == 0 && max == 0) {
min = policy.cpuinfo.min_freq;
max = policy.cpuinfo.max_freq;
} else {
if (min != policy.cpuinfo.min_freq ||
max != policy.cpuinfo.max_freq)
return ERR_PTR(-EINVAL);
}
}
cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
GFP_KERNEL);
if (!cpufreq_dev)
return ERR_PTR(-ENOMEM);
cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
if (ret) {
kfree(cpufreq_dev);
return ERR_PTR(-EINVAL);
}
snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
cpufreq_dev->id);
cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
&cpufreq_cooling_ops);
if (!cool_dev) {
release_idr(&cpufreq_idr, cpufreq_dev->id);
kfree(cpufreq_dev);
return ERR_PTR(-EINVAL);
}
cpufreq_dev->cool_dev = cool_dev;
cpufreq_dev->cpufreq_state = 0;
mutex_lock(&cooling_cpufreq_lock);
/* Register the notifier for first cpufreq cooling device */
if (cpufreq_dev_count == 0)
cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
cpufreq_dev_count++;
mutex_unlock(&cooling_cpufreq_lock);
return cool_dev;
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
/**
* cpufreq_cooling_unregister - function to remove cpufreq cooling device.
* @cdev: thermal cooling device pointer.
*
* This interface function unregisters the "thermal-cpufreq-%x" cooling device.
*/
void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
{
struct cpufreq_cooling_device *cpufreq_dev = cdev->devdata;
mutex_lock(&cooling_cpufreq_lock);
cpufreq_dev_count--;
/* Unregister the notifier for the last cpufreq cooling device */
if (cpufreq_dev_count == 0)
cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
mutex_unlock(&cooling_cpufreq_lock);
thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
release_idr(&cpufreq_idr, cpufreq_dev->id);
kfree(cpufreq_dev);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);