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

   1 /*
   2  * Thermal throttle event support code (such as syslog messaging and rate
   3  * limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
   4  *
   5  * This allows consistent reporting of CPU thermal throttle events.
   6  *
   7  * Maintains a counter in /sys that keeps track of the number of thermal
   8  * events, such that the user knows how bad the thermal problem might be
   9  * (since the logging to syslog and mcelog is rate limited).
  10  *
  11  * Author: Dmitriy Zavin (dmitriyz@google.com)
  12  *
  13  * Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
  14  *          Inspired by Ross Biro's and Al Borchers' counter code.
  15  */
  16 #include <linux/notifier.h>
  17 #include <linux/jiffies.h>
  18 #include <linux/percpu.h>
  19 #include <linux/sysdev.h>
  20 #include <linux/cpu.h>
  21
  22 #include <asm/therm_throt.h>
  23
  24 /* How long to wait between reporting thermal events */
  25 #define CHECK_INTERVAL          (300 * HZ)
  26
  27 static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
  28 static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
  29
  30 atomic_t therm_throt_en         = ATOMIC_INIT(0);
  31
  32 #ifdef CONFIG_SYSFS
  33 #define define_therm_throt_sysdev_one_ro(_name)                         \
  34         static SYSDEV_ATTR(_name, 0444, therm_throt_sysdev_show_##_name, NULL)
  35
  36 #define define_therm_throt_sysdev_show_func(name)                       \
  37 static ssize_t therm_throt_sysdev_show_##name(struct sys_device *dev,   \
  38                                         struct sysdev_attribute *attr,  \
  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,
 117                                   &thermal_throttle_attr_group);
 118 }
 119
 120 static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
 121 {
 122         sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
 123 }
 124
 125 /* Mutex protecting device creation against CPU hotplug: */
 126 static DEFINE_MUTEX(therm_cpu_lock);
 127
 128 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
 129 static __cpuinit int
 130 thermal_throttle_cpu_callback(struct notifier_block *nfb,
 131                               unsigned long action,
 132                               void *hcpu)
 133 {
 134         unsigned int cpu = (unsigned long)hcpu;
 135         struct sys_device *sys_dev;
 136         int err = 0;
 137
 138         sys_dev = get_cpu_sysdev(cpu);
 139
 140         switch (action) {
 141         case CPU_UP_PREPARE:
 142         case CPU_UP_PREPARE_FROZEN:
 143                 mutex_lock(&therm_cpu_lock);
 144                 err = thermal_throttle_add_dev(sys_dev);
 145                 mutex_unlock(&therm_cpu_lock);
 146                 WARN_ON(err);
 147                 break;
 148         case CPU_UP_CANCELED:
 149         case CPU_UP_CANCELED_FROZEN:
 150         case CPU_DEAD:
 151         case CPU_DEAD_FROZEN:
 152                 mutex_lock(&therm_cpu_lock);
 153                 thermal_throttle_remove_dev(sys_dev);
 154                 mutex_unlock(&therm_cpu_lock);
 155                 break;
 156         }
 157         return err ? NOTIFY_BAD : NOTIFY_OK;
 158 }
 159
 160 static struct notifier_block thermal_throttle_cpu_notifier __cpuinitdata =
 161 {
 162         .notifier_call = thermal_throttle_cpu_callback,
 163 };
 164
 165 static __init int thermal_throttle_init_device(void)
 166 {
 167         unsigned int cpu = 0;
 168         int err;
 169
 170         if (!atomic_read(&therm_throt_en))
 171                 return 0;
 172
 173         register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
 174
 175 #ifdef CONFIG_HOTPLUG_CPU
 176         mutex_lock(&therm_cpu_lock);
 177 #endif
 178         /* connect live CPUs to sysfs */
 179         for_each_online_cpu(cpu) {
 180                 err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
 181                 WARN_ON(err);
 182         }
 183 #ifdef CONFIG_HOTPLUG_CPU
 184         mutex_unlock(&therm_cpu_lock);
 185 #endif
 186
 187         return 0;
 188 }
 189
 190 device_initcall(thermal_throttle_init_device);
 191 #endif /* CONFIG_SYSFS */