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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
29static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
30static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
31atomic_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) \
38static 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
55define_therm_throt_sysdev_show_func(count);
56define_therm_throt_sysdev_one_ro(count);
57
58static struct attribute *thermal_throttle_attrs[] = {
59 &attr_count.attr,
60 NULL
61};
62
63static 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 */
85int 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 */
114static __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
119static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
120{
121 return sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
122}
123
124/* Mutex protecting device creation against CPU hotplug */
125static DEFINE_MUTEX(therm_cpu_lock);
126
127/* Get notified when a cpu comes on/off. Be hotplug friendly. */
128static __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;
135
136 sys_dev = get_cpu_sysdev(cpu);
137 switch (action) {
138 case CPU_ONLINE:
139 case CPU_ONLINE_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_DEAD:
146 case CPU_DEAD_FROZEN:
147 mutex_lock(&therm_cpu_lock);
148 thermal_throttle_remove_dev(sys_dev);
149 mutex_unlock(&therm_cpu_lock);
150 break;
151 }
152 return NOTIFY_OK;
153}
154
155static struct notifier_block thermal_throttle_cpu_notifier =
156{
157 .notifier_call = thermal_throttle_cpu_callback,
158};
159
160static __init int thermal_throttle_init_device(void)
161{
162 unsigned int cpu = 0;
163 int err;
164
165 if (!atomic_read(&therm_throt_en))
166 return 0;
167
168 register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
169
170#ifdef CONFIG_HOTPLUG_CPU
171 mutex_lock(&therm_cpu_lock);
172#endif
173 /* connect live CPUs to sysfs */
174 for_each_online_cpu(cpu) {
175 err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
176 WARN_ON(err);
177 }
178#ifdef CONFIG_HOTPLUG_CPU
179 mutex_unlock(&therm_cpu_lock);
180#endif
181
182 return 0;
183}
184
185device_initcall(thermal_throttle_init_device);
186#endif /* CONFIG_SYSFS */
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