arch/i386/kernel/cpu/mcheck/therm_throt.c

   1 /*
   2  * linux/arch/i386/kerne/cpu/mcheck/therm_throt.c
   3  *
   4  * Thermal throttle event support code.
   5  *
   6  * Author: Dmitriy Zavin (dmitriyz@google.com)
   7  *
   8  * Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
   9  *
  10  */
  11
  12 #include <linux/percpu.h>
  13 #include <linux/cpu.h>
  14 #include <asm/cpu.h>
  15 #include <linux/notifier.h>
  16 #include <asm/therm_throt.h>
  17
  18 /* How long to wait between reporting thermal events */
  19 #define CHECK_INTERVAL              (300 * HZ)
  20
  21 static DEFINE_PER_CPU(__u64, next_check);
  22
  23 /***
  24  * therm_throt_process - Process thermal throttling event
  25  * @curr: Whether the condition is current or not (boolean), since the
  26  *        thermal interrupt normally gets called both when the thermal
  27  *        event begins and once the event has ended.
  28  *
  29  * This function is normally called by the thermal interrupt after the
  30  * IRQ has been acknowledged.
  31  *
  32  * It will take care of rate limiting and printing messages to the syslog.
  33  *
  34  * Returns: 0 : Event should NOT be further logged, i.e. still in
  35  *              "timeout" from previous log message.
  36  *          1 : Event should be logged further, and a message has been
  37  *              printed to the syslog.
  38  */
  39 int therm_throt_process(int curr)
  40 {
  41         unsigned int cpu = smp_processor_id();
  42         __u64 tmp_jiffs = get_jiffies_64();
  43
  44         if (time_before64(tmp_jiffs, __get_cpu_var(next_check)))
  45                 return 0;
  46
  47         __get_cpu_var(next_check) = tmp_jiffs + CHECK_INTERVAL;
  48
  49         /* if we just entered the thermal event */
  50         if (curr) {
  51                 printk(KERN_CRIT "CPU%d: Temperature above threshold, "
  52                        "cpu clock throttled\n", cpu);
  53                 add_taint(TAINT_MACHINE_CHECK);
  54         } else {
  55                 printk(KERN_CRIT "CPU%d: Temperature/speed normal\n", cpu);
  56         }
  57
  58         return 1;
  59 }