2. sysfs attributes structure
RO read only value
+WO write only value
RW read/write value
Thermal sysfs attributes will be represented under /sys/class/thermal.
|---type: Type of the cooling device(processor/fan/...)
|---max_state: Maximum cooling state of the cooling device
|---cur_state: Current cooling state of the cooling device
+ |---stats: Directory containing cooling device's statistics
+ |---stats/reset: Writing any value resets the statistics
+ |---stats/time_in_state_ms: Time (msec) spent in various cooling states
+ |---stats/total_trans: Total number of times cooling state is changed
+ |---stats/trans_table: Cooing state transition table
Then next two dynamic attributes are created/removed in pairs. They represent
- cur_state == max_state means the maximum cooling.
RW, Required
+stats/reset
+ Writing any value resets the cooling device's statistics.
+ WO, Required
+
+stats/time_in_state_ms:
+ The amount of time spent by the cooling device in various cooling
+ states. The output will have "<state> <time>" pair in each line, which
+ will mean this cooling device spent <time> msec of time at <state>.
+ Output will have one line for each of the supported states. usertime
+ units here is 10mS (similar to other time exported in /proc).
+ RO, Required
+
+stats/total_trans:
+ A single positive value showing the total number of times the state of a
+ cooling device is changed.
+ RO, Required
+
+stats/trans_table:
+ This gives fine grained information about all the cooling state
+ transitions. The cat output here is a two dimensional matrix, where an
+ entry <i,j> (row i, column j) represents the number of transitions from
+ State_i to State_j. If the transition table is bigger than PAGE_SIZE,
+ reading this will return an -EFBIG error.
+ RO, Required
+
3. A simple implementation
ACPI thermal zone may support multiple trip points like critical, hot,
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/string.h>
+#include <linux/jiffies.h>
#include "thermal_core.h"
result = cdev->ops->set_cur_state(cdev, state);
if (result)
return result;
+ thermal_cooling_device_stats_update(cdev, state);
return count;
}
static const struct attribute_group *cooling_device_attr_groups[] = {
&cooling_device_attr_group,
+ NULL, /* Space allocated for cooling_device_stats_attr_group */
NULL,
};
+#ifdef CONFIG_THERMAL_STATISTICS
+struct cooling_dev_stats {
+ spinlock_t lock;
+ unsigned int total_trans;
+ unsigned long state;
+ unsigned long max_states;
+ ktime_t last_time;
+ ktime_t *time_in_state;
+ unsigned int *trans_table;
+};
+
+static void update_time_in_state(struct cooling_dev_stats *stats)
+{
+ ktime_t now = ktime_get(), delta;
+
+ delta = ktime_sub(now, stats->last_time);
+ stats->time_in_state[stats->state] =
+ ktime_add(stats->time_in_state[stats->state], delta);
+ stats->last_time = now;
+}
+
+void thermal_cooling_device_stats_update(struct thermal_cooling_device *cdev,
+ unsigned long new_state)
+{
+ struct cooling_dev_stats *stats = cdev->stats;
+
+ spin_lock(&stats->lock);
+
+ if (stats->state == new_state)
+ goto unlock;
+
+ update_time_in_state(stats);
+ stats->trans_table[stats->state * stats->max_states + new_state]++;
+ stats->state = new_state;
+ stats->total_trans++;
+
+unlock:
+ spin_unlock(&stats->lock);
+}
+
+static ssize_t
+thermal_cooling_device_total_trans_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct thermal_cooling_device *cdev = to_cooling_device(dev);
+ struct cooling_dev_stats *stats = cdev->stats;
+ int ret;
+
+ spin_lock(&stats->lock);
+ ret = sprintf(buf, "%u\n", stats->total_trans);
+ spin_unlock(&stats->lock);
+
+ return ret;
+}
+
+static ssize_t
+thermal_cooling_device_time_in_state_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct thermal_cooling_device *cdev = to_cooling_device(dev);
+ struct cooling_dev_stats *stats = cdev->stats;
+ ssize_t len = 0;
+ int i;
+
+ spin_lock(&stats->lock);
+ update_time_in_state(stats);
+
+ for (i = 0; i < stats->max_states; i++) {
+ len += sprintf(buf + len, "state%u\t%llu\n", i,
+ ktime_to_ms(stats->time_in_state[i]));
+ }
+ spin_unlock(&stats->lock);
+
+ return len;
+}
+
+static ssize_t
+thermal_cooling_device_reset_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct thermal_cooling_device *cdev = to_cooling_device(dev);
+ struct cooling_dev_stats *stats = cdev->stats;
+ int i, states = stats->max_states;
+
+ spin_lock(&stats->lock);
+
+ stats->total_trans = 0;
+ stats->last_time = ktime_get();
+ memset(stats->trans_table, 0,
+ states * states * sizeof(*stats->trans_table));
+
+ for (i = 0; i < stats->max_states; i++)
+ stats->time_in_state[i] = ktime_set(0, 0);
+
+ spin_unlock(&stats->lock);
+
+ return count;
+}
+
+static ssize_t
+thermal_cooling_device_trans_table_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct thermal_cooling_device *cdev = to_cooling_device(dev);
+ struct cooling_dev_stats *stats = cdev->stats;
+ ssize_t len = 0;
+ int i, j;
+
+ len += snprintf(buf + len, PAGE_SIZE - len, " From : To\n");
+ len += snprintf(buf + len, PAGE_SIZE - len, " : ");
+ for (i = 0; i < stats->max_states; i++) {
+ if (len >= PAGE_SIZE)
+ break;
+ len += snprintf(buf + len, PAGE_SIZE - len, "state%2u ", i);
+ }
+ if (len >= PAGE_SIZE)
+ return PAGE_SIZE;
+
+ len += snprintf(buf + len, PAGE_SIZE - len, "\n");
+
+ for (i = 0; i < stats->max_states; i++) {
+ if (len >= PAGE_SIZE)
+ break;
+
+ len += snprintf(buf + len, PAGE_SIZE - len, "state%2u:", i);
+
+ for (j = 0; j < stats->max_states; j++) {
+ if (len >= PAGE_SIZE)
+ break;
+ len += snprintf(buf + len, PAGE_SIZE - len, "%8u ",
+ stats->trans_table[i * stats->max_states + j]);
+ }
+ if (len >= PAGE_SIZE)
+ break;
+ len += snprintf(buf + len, PAGE_SIZE - len, "\n");
+ }
+
+ if (len >= PAGE_SIZE) {
+ pr_warn_once("Thermal transition table exceeds PAGE_SIZE. Disabling\n");
+ return -EFBIG;
+ }
+ return len;
+}
+
+static DEVICE_ATTR(total_trans, 0444, thermal_cooling_device_total_trans_show,
+ NULL);
+static DEVICE_ATTR(time_in_state_ms, 0444,
+ thermal_cooling_device_time_in_state_show, NULL);
+static DEVICE_ATTR(reset, 0200, NULL, thermal_cooling_device_reset_store);
+static DEVICE_ATTR(trans_table, 0444,
+ thermal_cooling_device_trans_table_show, NULL);
+
+static struct attribute *cooling_device_stats_attrs[] = {
+ &dev_attr_total_trans.attr,
+ &dev_attr_time_in_state_ms.attr,
+ &dev_attr_reset.attr,
+ &dev_attr_trans_table.attr,
+ NULL
+};
+
+static const struct attribute_group cooling_device_stats_attr_group = {
+ .attrs = cooling_device_stats_attrs,
+ .name = "stats"
+};
+
+static void cooling_device_stats_setup(struct thermal_cooling_device *cdev)
+{
+ struct cooling_dev_stats *stats;
+ unsigned long states;
+ int var;
+
+ if (cdev->ops->get_max_state(cdev, &states))
+ return;
+
+ states++; /* Total number of states is highest state + 1 */
+
+ var = sizeof(*stats);
+ var += sizeof(*stats->time_in_state) * states;
+ var += sizeof(*stats->trans_table) * states * states;
+
+ stats = kzalloc(var, GFP_KERNEL);
+ if (!stats)
+ return;
+
+ stats->time_in_state = (ktime_t *)(stats + 1);
+ stats->trans_table = (unsigned int *)(stats->time_in_state + states);
+ cdev->stats = stats;
+ stats->last_time = ktime_get();
+ stats->max_states = states;
+
+ spin_lock_init(&stats->lock);
+
+ /* Fill the empty slot left in cooling_device_attr_groups */
+ var = ARRAY_SIZE(cooling_device_attr_groups) - 2;
+ cooling_device_attr_groups[var] = &cooling_device_stats_attr_group;
+}
+
+static void cooling_device_stats_destroy(struct thermal_cooling_device *cdev)
+{
+ kfree(cdev->stats);
+ cdev->stats = NULL;
+}
+
+#else
+
+static inline void
+cooling_device_stats_setup(struct thermal_cooling_device *cdev) {}
+static inline void
+cooling_device_stats_destroy(struct thermal_cooling_device *cdev) {}
+
+#endif /* CONFIG_THERMAL_STATISTICS */
+
void thermal_cooling_device_setup_sysfs(struct thermal_cooling_device *cdev)
{
+ cooling_device_stats_setup(cdev);
cdev->device.groups = cooling_device_attr_groups;
}
+void thermal_cooling_device_destroy_sysfs(struct thermal_cooling_device *cdev)
+{
+ cooling_device_stats_destroy(cdev);
+}
+
/* these helper will be used only at the time of bindig */
ssize_t
thermal_cooling_device_trip_point_show(struct device *dev,
projects / linux-2.6-block.git / commitdiff