/*
* processor_thermal.c - Passive cooling submodule of the ACPI processor driver
*
* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
* Copyright (C) 2004 Dominik Brodowski <linux@brodo.de>
* Copyright (C) 2004 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
* - Added processor hotplug support
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* 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; either version 2 of the License, or (at
* your option) any later version.
*
* 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/init.h>
#include <linux/cpufreq.h>
#include <linux/acpi.h>
#include <acpi/processor.h>
#include <asm/uaccess.h>
#define PREFIX "ACPI: "
#define ACPI_PROCESSOR_CLASS "processor"
#define _COMPONENT ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_thermal");
#ifdef CONFIG_CPU_FREQ
/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
* offers (in most cases) voltage scaling in addition to frequency scaling, and
* thus a cubic (instead of linear) reduction of energy. Also, we allow for
* _any_ cpufreq driver and not only the acpi-cpufreq driver.
*/
#define CPUFREQ_THERMAL_MIN_STEP 0
#define CPUFREQ_THERMAL_MAX_STEP 3
static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
static unsigned int acpi_thermal_cpufreq_is_init = 0;
#define reduction_pctg(cpu) \
per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
/*
* Emulate "per package data" using per cpu data (which should really be
* provided elsewhere)
*
* Note we can lose a CPU on cpu hotunplug, in this case we forget the state
* temporarily. Fortunately that's not a big issue here (I hope)
*/
static int phys_package_first_cpu(int cpu)
{
int i;
int id = topology_physical_package_id(cpu);
for_each_online_cpu(i)
if (topology_physical_package_id(i) == id)
return i;
return 0;
}
static int cpu_has_cpufreq(unsigned int cpu)
{
struct cpufreq_policy policy;
if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
return 0;
return 1;
}
static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
unsigned long event, void *data)
{
struct cpufreq_policy *policy = data;
unsigned long max_freq = 0;
if (event != CPUFREQ_ADJUST)
goto out;
max_freq = (
policy->cpuinfo.max_freq *
(100 - reduction_pctg(policy->cpu) * 20)
) / 100;
cpufreq_verify_within_limits(policy, 0, max_freq);
out:
return 0;
}
static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
.notifier_call = acpi_thermal_cpufreq_notifier,
};
static int cpufreq_get_max_state(unsigned int cpu)
{
if (!cpu_has_cpufreq(cpu))
return 0;
return CPUFREQ_THERMAL_MAX_STEP;
}
static int cpufreq_get_cur_state(unsigned int cpu)
{
if (!cpu_has_cpufreq(cpu))
return 0;
return reduction_pctg(cpu);
}
static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
int i;
if (!cpu_has_cpufreq(cpu))
return 0;
reduction_pctg(cpu) = state;
/*
* Update all the CPUs in the same package because they all
* contribute to the temperature and often share the same
* frequency.
*/
for_each_online_cpu(i) {
if (topology_physical_package_id(i) ==
topology_physical_package_id(cpu))
cpufreq_update_policy(i);
}
return 0;
}
void acpi_thermal_cpufreq_init(void)
{
int i;
i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
if (!i)
acpi_thermal_cpufreq_is_init = 1;
}
void acpi_thermal_cpufreq_exit(void)
{
if (acpi_thermal_cpufreq_is_init)
cpufreq_unregister_notifier
(&acpi_thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
acpi_thermal_cpufreq_is_init = 0;
}
#else /* ! CONFIG_CPU_FREQ */
static int cpufreq_get_max_state(unsigned int cpu)
{
return 0;
}
static int cpufreq_get_cur_state(unsigned int cpu)
{
return 0;
}
static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
return 0;
}
#endif
/* thermal cooling device callbacks */
static int acpi_processor_max_state(struct acpi_processor *pr)
{
int max_state = 0;
/*
* There exists four states according to
* cpufreq_thermal_reduction_pctg. 0, 1, 2, 3
*/
max_state += cpufreq_get_max_state(pr->id);
if (pr->flags.throttling)
max_state += (pr->throttling.state_count -1);
return max_state;
}
static int
processor_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct acpi_device *device = cdev->devdata;
struct acpi_processor *pr;
if (!device)
return -EINVAL;
pr = acpi_driver_data(device);
if (!pr)
return -EINVAL;
*state = acpi_processor_max_state(pr);
return 0;
}
static int
processor_get_cur_state(struct thermal_cooling_device *cdev,
unsigned long *cur_state)
{
struct acpi_device *device = cdev->devdata;
struct acpi_processor *pr;
if (!device)
return -EINVAL;
pr = acpi_driver_data(device);
if (!pr)
return -EINVAL;
*cur_state = cpufreq_get_cur_state(pr->id);
if (pr->flags.throttling)
*cur_state += pr->throttling.state;
return 0;
}
static int
processor_set_cur_state(struct thermal_cooling_device *cdev,
unsigned long state)
{
struct acpi_device *device = cdev->devdata;
struct acpi_processor *pr;
int result = 0;
int max_pstate;
if (!device)
return -EINVAL;
pr = acpi_driver_data(device);
if (!pr)
return -EINVAL;
max_pstate = cpufreq_get_max_state(pr->id);
if (state > acpi_processor_max_state(pr))
return -EINVAL;
if (state <= max_pstate) {
if (pr->flags.throttling && pr->throttling.state)
result = acpi_processor_set_throttling(pr, 0, false);
cpufreq_set_cur_state(pr->id, state);
} else {
cpufreq_set_cur_state(pr->id, max_pstate);
result = acpi_processor_set_throttling(pr,
state - max_pstate, false);
}
return result;
}
const struct thermal_cooling_device_ops processor_cooling_ops = {
.get_max_state = processor_get_max_state,
.get_cur_state = processor_get_cur_state,
.set_cur_state = processor_set_cur_state,
};