arch/x86/kernel/cpu/mcheck/therm_throt.c

   1 /*
   2  * linux/arch/i386/kernel/cpu/mcheck/therm_throt.c
   3  *
   4  * Thermal throttle event support code (such as syslog messaging and rate
   5  * limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
   6  * This allows consistent reporting of CPU thermal throttle events.
   7  *
   8  * Maintains a counter in /sys that keeps track of the number of thermal
   9  * events, such that the user knows how bad the thermal problem might be
  10  * (since the logging to syslog and mcelog is rate limited).
  11  *
  12  * Author: Dmitriy Zavin (dmitriyz@google.com)
  13  *
  14  * Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
  15  *          Inspired by Ross Biro's and Al Borchers' counter code.
  16  */
  17
  18 #include <linux/percpu.h>
  19 #include <linux/sysdev.h>
  20 #include <linux/cpu.h>
  21 #include <asm/cpu.h>
  22 #include <linux/notifier.h>
  23 #include <linux/jiffies.h>
  24 #include <asm/therm_throt.h>
  25
  26 /* How long to wait between reporting thermal events */
  27 #define CHECK_INTERVAL              (300 * HZ)
  28
  29 static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
  30 static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
  31 atomic_t therm_throt_en = ATOMIC_INIT(0);
  32
  33 #ifdef CONFIG_SYSFS
  34 #define define_therm_throt_sysdev_one_ro(_name)                              \
  35         static SYSDEV_ATTR(_name, 0444, therm_throt_sysdev_show_##_name, NULL)
  36
  37 #define define_therm_throt_sysdev_show_func(name)                            \
  38 static ssize_t therm_throt_sysdev_show_##name(struct sys_device *dev,        \
  39                                               char *buf)                     \
  40 {                                                                            \
  41         unsigned int cpu = dev->id;                                          \
  42         ssize_t ret;                                                         \
  43                                                                              \
  44         preempt_disable();              /* CPU hotplug */                    \
  45         if (cpu_online(cpu))                                                 \
  46                 ret = sprintf(buf, "%lu\n",                                  \
  47                               per_cpu(thermal_throttle_##name, cpu));        \
  48         else                                                                 \
  49                 ret = 0;                                                     \
  50         preempt_enable();                                                    \
  51                                                                              \
  52         return ret;                                                          \
  53 }
  54
  55 define_therm_throt_sysdev_show_func(count);
  56 define_therm_throt_sysdev_one_ro(count);
  57
  58 static struct attribute *thermal_throttle_attrs[] = {
  59         &attr_count.attr,
  60         NULL
  61 };
  62
  63 static struct attribute_group thermal_throttle_attr_group = {
  64         .attrs = thermal_throttle_attrs,
  65         .name = "thermal_throttle"
  66 };
  67 #endif /* CONFIG_SYSFS */
  68
  69 /***
  70  * therm_throt_process - Process thermal throttling event from interrupt
  71  * @curr: Whether the condition is current or not (boolean), since the
  72  *        thermal interrupt normally gets called both when the thermal
  73  *        event begins and once the event has ended.
  74  *
  75  * This function is called by the thermal interrupt after the
  76  * IRQ has been acknowledged.
  77  *
  78  * It will take care of rate limiting and printing messages to the syslog.
  79  *
  80  * Returns: 0 : Event should NOT be further logged, i.e. still in
  81  *              "timeout" from previous log message.
  82  *          1 : Event should be logged further, and a message has been
  83  *              printed to the syslog.
  84  */
  85 int therm_throt_process(int curr)
  86 {
  87         unsigned int cpu = smp_processor_id();
  88         __u64 tmp_jiffs = get_jiffies_64();
  89
  90         if (curr)
  91                 __get_cpu_var(thermal_throttle_count)++;
  92
  93         if (time_before64(tmp_jiffs, __get_cpu_var(next_check)))
  94                 return 0;
  95
  96         __get_cpu_var(next_check) = tmp_jiffs + CHECK_INTERVAL;
  97
  98         /* if we just entered the thermal event */
  99         if (curr) {
 100                 printk(KERN_CRIT "CPU%d: Temperature above threshold, "
 101                        "cpu clock throttled (total events = %lu)\n", cpu,
 102                        __get_cpu_var(thermal_throttle_count));
 103
 104                 add_taint(TAINT_MACHINE_CHECK);
 105         } else {
 106                 printk(KERN_CRIT "CPU%d: Temperature/speed normal\n", cpu);
 107         }
 108
 109         return 1;
 110 }
 111
 112 #ifdef CONFIG_SYSFS
 113 /* Add/Remove thermal_throttle interface for CPU device */
 114 static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
 115 {
 116         return sysfs_create_group(&sys_dev->kobj, &thermal_throttle_attr_group);
 117 }
 118
 119 static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
 120 {
 121         sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
 122 }
 123
 124 /* Mutex protecting device creation against CPU hotplug */
 125 static DEFINE_MUTEX(therm_cpu_lock);
 126
 127 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
 128 static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block *nfb,
 129                                                    unsigned long action,
 130                                                    void *hcpu)
 131 {
 132         unsigned int cpu = (unsigned long)hcpu;
 133         struct sys_device *sys_dev;
 134         int err = 0;
 135
 136         sys_dev = get_cpu_sysdev(cpu);
 137         switch (action) {
 138         case CPU_UP_PREPARE:
 139         case CPU_UP_PREPARE_FROZEN:
 140                 mutex_lock(&therm_cpu_lock);
 141                 err = thermal_throttle_add_dev(sys_dev);
 142                 mutex_unlock(&therm_cpu_lock);
 143                 WARN_ON(err);
 144                 break;
 145         case CPU_UP_CANCELED:
 146         case CPU_UP_CANCELED_FROZEN:
 147         case CPU_DEAD:
 148         case CPU_DEAD_FROZEN:
 149                 mutex_lock(&therm_cpu_lock);
 150                 thermal_throttle_remove_dev(sys_dev);
 151                 mutex_unlock(&therm_cpu_lock);
 152                 break;
 153         }
 154         return err ? NOTIFY_BAD : NOTIFY_OK;
 155 }
 156
 157 static struct notifier_block thermal_throttle_cpu_notifier __cpuinitdata =
 158 {
 159         .notifier_call = thermal_throttle_cpu_callback,
 160 };
 161
 162 static __init int thermal_throttle_init_device(void)
 163 {
 164         unsigned int cpu = 0;
 165         int err;
 166
 167         if (!atomic_read(&therm_throt_en))
 168                 return 0;
 169
 170         register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
 171
 172 #ifdef CONFIG_HOTPLUG_CPU
 173         mutex_lock(&therm_cpu_lock);
 174 #endif
 175         /* connect live CPUs to sysfs */
 176         for_each_online_cpu(cpu) {
 177                 err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
 178                 WARN_ON(err);
 179         }
 180 #ifdef CONFIG_HOTPLUG_CPU
 181         mutex_unlock(&therm_cpu_lock);
 182 #endif
 183
 184         return 0;
 185 }
 186
 187 device_initcall(thermal_throttle_init_device);
 188 #endif /* CONFIG_SYSFS */