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 #include <asm/cpu.h>
  24
  25 /* How long to wait between reporting thermal events */
  26 #define CHECK_INTERVAL          (300 * HZ)
  27
  28 static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
  29 static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
  30
  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                                         struct sysdev_attribute *attr,  \
  40                                               char *buf)                \
  41 {                                                                       \
  42         unsigned int cpu = dev->id;                                     \
  43         ssize_t ret;                                                    \
  44                                                                         \
  45         preempt_disable();      /* CPU hotplug */                       \
  46         if (cpu_online(cpu))                                            \
  47                 ret = sprintf(buf, "%lu\n",                             \
  48                               per_cpu(thermal_throttle_##name, cpu));   \
  49         else                                                            \
  50                 ret = 0;                                                \
  51         preempt_enable();                                               \
  52                                                                         \
  53         return ret;                                                     \
  54 }
  55
  56 define_therm_throt_sysdev_show_func(count);
  57 define_therm_throt_sysdev_one_ro(count);
  58
  59 static struct attribute *thermal_throttle_attrs[] = {
  60         &attr_count.attr,
  61         NULL
  62 };
  63
  64 static struct attribute_group thermal_throttle_attr_group = {
  65         .attrs  = thermal_throttle_attrs,
  66         .name   = "thermal_throttle"
  67 };
  68 #endif /* CONFIG_SYSFS */
  69
  70 /***
  71  * therm_throt_process - Process thermal throttling event from interrupt
  72  * @curr: Whether the condition is current or not (boolean), since the
  73  *        thermal interrupt normally gets called both when the thermal
  74  *        event begins and once the event has ended.
  75  *
  76  * This function is called by the thermal interrupt after the
  77  * IRQ has been acknowledged.
  78  *
  79  * It will take care of rate limiting and printing messages to the syslog.
  80  *
  81  * Returns: 0 : Event should NOT be further logged, i.e. still in
  82  *              "timeout" from previous log message.
  83  *          1 : Event should be logged further, and a message has been
  84  *              printed to the syslog.
  85  */
  86 int therm_throt_process(int curr)
  87 {
  88         unsigned int cpu = smp_processor_id();
  89         __u64 tmp_jiffs = get_jiffies_64();
  90
  91         if (curr)
  92                 __get_cpu_var(thermal_throttle_count)++;
  93
  94         if (time_before64(tmp_jiffs, __get_cpu_var(next_check)))
  95                 return 0;
  96
  97         __get_cpu_var(next_check) = tmp_jiffs + CHECK_INTERVAL;
  98
  99         /* if we just entered the thermal event */
 100         if (curr) {
 101                 printk(KERN_CRIT "CPU%d: Temperature above threshold, "
 102                        "cpu clock throttled (total events = %lu)\n", cpu,
 103                        __get_cpu_var(thermal_throttle_count));
 104
 105                 add_taint(TAINT_MACHINE_CHECK);
 106         } else {
 107                 printk(KERN_CRIT "CPU%d: Temperature/speed normal\n", cpu);
 108         }
 109
 110         return 1;
 111 }
 112
 113 #ifdef CONFIG_SYSFS
 114 /* Add/Remove thermal_throttle interface for CPU device: */
 115 static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
 116 {
 117         return sysfs_create_group(&sys_dev->kobj,
 118                                   &thermal_throttle_attr_group);
 119 }
 120
 121 static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
 122 {
 123         sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
 124 }
 125
 126 /* Mutex protecting device creation against CPU hotplug: */
 127 static DEFINE_MUTEX(therm_cpu_lock);
 128
 129 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
 130 static __cpuinit int
 131 thermal_throttle_cpu_callback(struct notifier_block *nfb,
 132                               unsigned long action,
 133                               void *hcpu)
 134 {
 135         unsigned int cpu = (unsigned long)hcpu;
 136         struct sys_device *sys_dev;
 137         int err = 0;
 138
 139         sys_dev = get_cpu_sysdev(cpu);
 140
 141         switch (action) {
 142         case CPU_UP_PREPARE:
 143         case CPU_UP_PREPARE_FROZEN:
 144                 mutex_lock(&therm_cpu_lock);
 145                 err = thermal_throttle_add_dev(sys_dev);
 146                 mutex_unlock(&therm_cpu_lock);
 147                 WARN_ON(err);
 148                 break;
 149         case CPU_UP_CANCELED:
 150         case CPU_UP_CANCELED_FROZEN:
 151         case CPU_DEAD:
 152         case CPU_DEAD_FROZEN:
 153                 mutex_lock(&therm_cpu_lock);
 154                 thermal_throttle_remove_dev(sys_dev);
 155                 mutex_unlock(&therm_cpu_lock);
 156                 break;
 157         }
 158         return err ? NOTIFY_BAD : NOTIFY_OK;
 159 }
 160
 161 static struct notifier_block thermal_throttle_cpu_notifier __cpuinitdata =
 162 {
 163         .notifier_call = thermal_throttle_cpu_callback,
 164 };
 165
 166 static __init int thermal_throttle_init_device(void)
 167 {
 168         unsigned int cpu = 0;
 169         int err;
 170
 171         if (!atomic_read(&therm_throt_en))
 172                 return 0;
 173
 174         register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
 175
 176 #ifdef CONFIG_HOTPLUG_CPU
 177         mutex_lock(&therm_cpu_lock);
 178 #endif
 179         /* connect live CPUs to sysfs */
 180         for_each_online_cpu(cpu) {
 181                 err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
 182                 WARN_ON(err);
 183         }
 184 #ifdef CONFIG_HOTPLUG_CPU
 185         mutex_unlock(&therm_cpu_lock);
 186 #endif
 187
 188         return 0;
 189 }
 190
 191 device_initcall(thermal_throttle_init_device);
 192 #endif /* CONFIG_SYSFS */