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/*
* linux/arch/i386/kerne/cpu/mcheck/therm_throt.c
*
* Thermal throttle event support code (such as syslog messaging and rate
* limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
* This allows consistent reporting of CPU thermal throttle events.
*
* Maintains a counter in /sys that keeps track of the number of thermal
* events, such that the user knows how bad the thermal problem might be
* (since the logging to syslog and mcelog is rate limited).
*
* Author: Dmitriy Zavin (dmitriyz@google.com)
*
* Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
* Inspired by Ross Biro's and Al Borchers' counter code.
*/
#include <linux/percpu.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <asm/cpu.h>
#include <linux/notifier.h>
#include <asm/therm_throt.h>
/* How long to wait between reporting thermal events */
#define CHECK_INTERVAL (300 * HZ)
static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
atomic_t therm_throt_en = ATOMIC_INIT(0);
#ifdef CONFIG_SYSFS
#define define_therm_throt_sysdev_one_ro(_name) \
static SYSDEV_ATTR(_name, 0444, therm_throt_sysdev_show_##_name, NULL)
#define define_therm_throt_sysdev_show_func(name) \
static ssize_t therm_throt_sysdev_show_##name(struct sys_device *dev, \
char *buf) \
{ \
unsigned int cpu = dev->id; \
ssize_t ret; \
\
preempt_disable(); /* CPU hotplug */ \
if (cpu_online(cpu)) \
ret = sprintf(buf, "%lu\n", \
per_cpu(thermal_throttle_##name, cpu)); \
else \
ret = 0; \
preempt_enable(); \
\
return ret; \
}
define_therm_throt_sysdev_show_func(count);
define_therm_throt_sysdev_one_ro(count);
static struct attribute *thermal_throttle_attrs[] = {
&attr_count.attr,
NULL
};
static struct attribute_group thermal_throttle_attr_group = {
.attrs = thermal_throttle_attrs,
.name = "thermal_throttle"
};
#endif /* CONFIG_SYSFS */
/***
* therm_throt_process - Process thermal throttling event from interrupt
* @curr: Whether the condition is current or not (boolean), since the
* thermal interrupt normally gets called both when the thermal
* event begins and once the event has ended.
*
* This function is called by the thermal interrupt after the
* IRQ has been acknowledged.
*
* It will take care of rate limiting and printing messages to the syslog.
*
* Returns: 0 : Event should NOT be further logged, i.e. still in
* "timeout" from previous log message.
* 1 : Event should be logged further, and a message has been
* printed to the syslog.
*/
int therm_throt_process(int curr)
{
unsigned int cpu = smp_processor_id();
__u64 tmp_jiffs = get_jiffies_64();
if (curr)
__get_cpu_var(thermal_throttle_count)++;
if (time_before64(tmp_jiffs, __get_cpu_var(next_check)))
return 0;
__get_cpu_var(next_check) = tmp_jiffs + CHECK_INTERVAL;
/* if we just entered the thermal event */
if (curr) {
printk(KERN_CRIT "CPU%d: Temperature above threshold, "
"cpu clock throttled (total events = %lu)\n", cpu,
__get_cpu_var(thermal_throttle_count));
add_taint(TAINT_MACHINE_CHECK);
} else {
printk(KERN_CRIT "CPU%d: Temperature/speed normal\n", cpu);
}
return 1;
}
#ifdef CONFIG_SYSFS
/* Add/Remove thermal_throttle interface for CPU device */
static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
{
return sysfs_create_group(&sys_dev->kobj, &thermal_throttle_attr_group);
}
#ifdef CONFIG_HOTPLUG_CPU
static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
{
return sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
}
/* Mutex protecting device creation against CPU hotplug */
static DEFINE_MUTEX(therm_cpu_lock);
/* Get notified when a cpu comes on/off. Be hotplug friendly. */
static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
struct sys_device *sys_dev;
int err;
sys_dev = get_cpu_sysdev(cpu);
mutex_lock(&therm_cpu_lock);
switch (action) {
case CPU_ONLINE:
err = thermal_throttle_add_dev(sys_dev);
WARN_ON(err);
break;
case CPU_DEAD:
thermal_throttle_remove_dev(sys_dev);
break;
}
mutex_unlock(&therm_cpu_lock);
return NOTIFY_OK;
}
static struct notifier_block thermal_throttle_cpu_notifier =
{
.notifier_call = thermal_throttle_cpu_callback,
};
#endif /* CONFIG_HOTPLUG_CPU */
static __init int thermal_throttle_init_device(void)
{
unsigned int cpu = 0;
int err;
if (!atomic_read(&therm_throt_en))
return 0;
register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
#ifdef CONFIG_HOTPLUG_CPU
mutex_lock(&therm_cpu_lock);
#endif
/* connect live CPUs to sysfs */
for_each_online_cpu(cpu) {
err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
WARN_ON(err);
}
#ifdef CONFIG_HOTPLUG_CPU
mutex_unlock(&therm_cpu_lock);
#endif
return 0;
}
device_initcall(thermal_throttle_init_device);
#endif /* CONFIG_SYSFS */
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