/*
* 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/kernel.h>
#include <linux/module.h>
#include <linux/thermal.h>
#include <linux/platform_device.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
* @id: unique integer value corresponding to each cpufreq_cooling_device
* registered.
* @cool_dev: thermal_cooling_device pointer to keep track of the the
* egistered 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.
* @node: list_head to link all cpufreq_cooling_device together.
*
* This structure is required for keeping information of each
* cpufreq_cooling_device registered as a list whose head is represented by
* cooling_cpufreq_list. In order to prevent corruption of this list 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;
struct list_head node;
};
static LIST_HEAD(cooling_cpufreq_list);
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.
*/
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 if a cpu has frequency transition policy.
* @cpu: cpu for which check is needed.
*/
static int is_cpufreq_valid(int cpu)
{
struct cpufreq_policy policy;
return !cpufreq_get_policy(&policy, cpu);
}
/**
* get_cpu_frequency - get the absolute value of frequency from level.
* @cpu: cpu for which frequency is fetched.
* @level: level of frequency, equals cooling state of cpu cooling device
* e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
*/
static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
{
int ret = 0, i = 0;
unsigned long level_index;
bool descend = false;
struct cpufreq_frequency_table *table =
cpufreq_frequency_get_table(cpu);
if (!table)
return ret;
while (table[i].frequency != CPUFREQ_TABLE_END) {
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;
/*check if table in ascending or descending order*/
if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
(table[i + 1].frequency < table[i].frequency)
&& !descend) {
descend = true;
}
/*return if level matched and table in descending order*/
if (descend && i == level)
return table[i].frequency;
i++;
}
i--;
if (level > i || descend)
return ret;
level_index = i - level;
/*Scan the table in reverse order and match the level*/
while (i >= 0) {
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;
/*return if level matched*/
if (i == level_index)
return table[i].frequency;
i--;
}
return ret;
}
/**
* 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.
*/
static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
unsigned long cooling_state)
{
unsigned int cpuid, clip_freq;
struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
unsigned int cpu = cpumask_any(maskPtr);
/* 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, maskPtr) {
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
*/
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.
*/
static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
unsigned int cpu;
struct cpufreq_frequency_table *table;
unsigned long count = 0;
int i = 0;
cpu = cpumask_any(maskPtr);
table = cpufreq_frequency_get_table(cpu);
if (!table) {
*state = 0;
return 0;
}
for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
continue;
count++;
}
if (count > 0) {
*state = --count;
return 0;
}
return -EINVAL;
}
/**
* 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.
*/
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.
*/
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.
*/
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);
}
sprintf(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(cpufreq_cooling_register);
/**
* cpufreq_cooling_unregister - function to remove cpufreq cooling device.
* @cdev: thermal cooling device pointer.
*/
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(cpufreq_cooling_unregister);
