diff options
Diffstat (limited to 'drivers/thermal/cpu_cooling.c')
| -rw-r--r-- | drivers/thermal/cpu_cooling.c | 107 |
1 files changed, 84 insertions, 23 deletions
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c index 768b508f0d69..a294921be650 100644 --- a/drivers/thermal/cpu_cooling.c +++ b/drivers/thermal/cpu_cooling.c @@ -20,10 +20,8 @@ * * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ -#include <linux/kernel.h> #include <linux/module.h> #include <linux/thermal.h> -#include <linux/platform_device.h> #include <linux/cpufreq.h> #include <linux/err.h> #include <linux/slab.h> @@ -31,21 +29,19 @@ #include <linux/cpu_cooling.h> /** - * struct cpufreq_cooling_device + * struct cpufreq_cooling_device - data for cooling device with cpufreq * @id: unique integer value corresponding to each cpufreq_cooling_device * registered. - * @cool_dev: thermal_cooling_device pointer to keep track of the the - * egistered cooling device. + * @cool_dev: thermal_cooling_device pointer to keep track of the + * registered cooling device. * @cpufreq_state: integer value representing the current state of cpufreq * cooling devices. * @cpufreq_val: integer value representing the absolute value of the clipped * frequency. * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device. - * @node: list_head to link all cpufreq_cooling_device together. * * This structure is required for keeping information of each - * cpufreq_cooling_device registered as a list whose head is represented by - * cooling_cpufreq_list. In order to prevent corruption of this list a + * cpufreq_cooling_device registered. In order to prevent corruption of this a * mutex lock cooling_cpufreq_lock is used. */ struct cpufreq_cooling_device { @@ -54,9 +50,7 @@ struct cpufreq_cooling_device { unsigned int cpufreq_state; unsigned int cpufreq_val; struct cpumask allowed_cpus; - struct list_head node; }; -static LIST_HEAD(cooling_cpufreq_list); static DEFINE_IDR(cpufreq_idr); static DEFINE_MUTEX(cooling_cpufreq_lock); @@ -99,8 +93,14 @@ static void release_idr(struct idr *idr, int id) /* Below code defines functions to be used for cpufreq as cooling device */ /** - * is_cpufreq_valid - function to check if a cpu has frequency transition policy. + * is_cpufreq_valid - function to check frequency transitioning capability. * @cpu: cpu for which check is needed. + * + * This function will check the current state of the system if + * it is capable of changing the frequency for a given @cpu. + * + * Return: 0 if the system is not currently capable of changing + * the frequency of given cpu. !0 in case the frequency is changeable. */ static int is_cpufreq_valid(int cpu) { @@ -114,8 +114,14 @@ enum cpufreq_cooling_property { GET_MAXL, }; -/* - * this is the common function to +/** + * get_property - fetch a property of interest for a give cpu. + * @cpu: cpu for which the property is required + * @input: query parameter + * @output: query return + * @property: type of query (frequency, level, max level) + * + * This is the common function to * 1. get maximum cpu cooling states * 2. translate frequency to cooling state * 3. translate cooling state to frequency @@ -124,12 +130,14 @@ enum cpufreq_cooling_property { * a) reduce duplicate code as most of the code can be shared. * b) make sure the logic is consistent when translating between * cooling states and frequencies. -*/ + * + * Return: 0 on success, -EINVAL when invalid parameters are passed. + */ static int get_property(unsigned int cpu, unsigned long input, unsigned int* output, enum cpufreq_cooling_property property) { int i, j; - unsigned long max_level = 0, level; + unsigned long max_level = 0, level = 0; unsigned int freq = CPUFREQ_ENTRY_INVALID; int descend = -1; struct cpufreq_frequency_table *table = @@ -196,6 +204,17 @@ static int get_property(unsigned int cpu, unsigned long input, return -EINVAL; } +/** + * cpufreq_cooling_get_level - for a give cpu, return the cooling level. + * @cpu: cpu for which the level is required + * @freq: the frequency of interest + * + * This function will match the cooling level corresponding to the + * requested @freq and return it. + * + * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID + * otherwise. + */ unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq) { unsigned int val; @@ -204,14 +223,19 @@ unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq) return THERMAL_CSTATE_INVALID; return (unsigned long)val; } - -EXPORT_SYMBOL(cpufreq_cooling_get_level); +EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level); /** * get_cpu_frequency - get the absolute value of frequency from level. * @cpu: cpu for which frequency is fetched. - * @level: level of frequency, equals cooling state of cpu cooling device + * @level: cooling level + * + * This function matches cooling level with frequency. Based on a cooling level + * of frequency, equals cooling state of cpu cooling device, it will return + * the corresponding frequency. * e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc + * + * Return: 0 on error, the corresponding frequency otherwise. */ static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level) { @@ -229,6 +253,12 @@ static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level) * @cpufreq_device: cpufreq_cooling_device pointer containing frequency * clipping data. * @cooling_state: value of the cooling state. + * + * Function used to make sure the cpufreq layer is aware of current thermal + * limits. The limits are applied by updating the cpufreq policy. + * + * Return: 0 on success, an error code otherwise (-EINVAL in case wrong + * cooling state). */ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device, unsigned long cooling_state) @@ -265,6 +295,12 @@ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device, * @nb: struct notifier_block * with callback info. * @event: value showing cpufreq event for which this function invoked. * @data: callback-specific data + * + * Callback to highjack the notification on cpufreq policy transition. + * Every time there is a change in policy, we will intercept and + * update the cpufreq policy with thermal constraints. + * + * Return: 0 (success) */ static int cpufreq_thermal_notifier(struct notifier_block *nb, unsigned long event, void *data) @@ -296,6 +332,11 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb, * cpufreq_get_max_state - callback function to get the max cooling state. * @cdev: thermal cooling device pointer. * @state: fill this variable with the max cooling state. + * + * Callback for the thermal cooling device to return the cpufreq + * max cooling state. + * + * Return: 0 on success, an error code otherwise. */ static int cpufreq_get_max_state(struct thermal_cooling_device *cdev, unsigned long *state) @@ -320,6 +361,11 @@ static int cpufreq_get_max_state(struct thermal_cooling_device *cdev, * cpufreq_get_cur_state - callback function to get the current cooling state. * @cdev: thermal cooling device pointer. * @state: fill this variable with the current cooling state. + * + * Callback for the thermal cooling device to return the cpufreq + * current cooling state. + * + * Return: 0 on success, an error code otherwise. */ static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev, unsigned long *state) @@ -334,6 +380,11 @@ static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev, * cpufreq_set_cur_state - callback function to set the current cooling state. * @cdev: thermal cooling device pointer. * @state: set this variable to the current cooling state. + * + * Callback for the thermal cooling device to change the cpufreq + * current cooling state. + * + * Return: 0 on success, an error code otherwise. */ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state) @@ -358,6 +409,13 @@ static struct notifier_block thermal_cpufreq_notifier_block = { /** * cpufreq_cooling_register - function to create cpufreq cooling device. * @clip_cpus: cpumask of cpus where the frequency constraints will happen. + * + * This interface function registers the cpufreq cooling device with the name + * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq + * cooling devices. + * + * Return: a valid struct thermal_cooling_device pointer on success, + * on failure, it returns a corresponding ERR_PTR(). */ struct thermal_cooling_device *cpufreq_cooling_register( const struct cpumask *clip_cpus) @@ -396,7 +454,8 @@ struct thermal_cooling_device *cpufreq_cooling_register( return ERR_PTR(-EINVAL); } - sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id); + snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d", + cpufreq_dev->id); cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev, &cpufreq_cooling_ops); @@ -418,11 +477,13 @@ struct thermal_cooling_device *cpufreq_cooling_register( mutex_unlock(&cooling_cpufreq_lock); return cool_dev; } -EXPORT_SYMBOL(cpufreq_cooling_register); +EXPORT_SYMBOL_GPL(cpufreq_cooling_register); /** * cpufreq_cooling_unregister - function to remove cpufreq cooling device. * @cdev: thermal cooling device pointer. + * + * This interface function unregisters the "thermal-cpufreq-%x" cooling device. */ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev) { @@ -432,14 +493,14 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev) cpufreq_dev_count--; /* Unregister the notifier for the last cpufreq cooling device */ - if (cpufreq_dev_count == 0) { + if (cpufreq_dev_count == 0) cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block, CPUFREQ_POLICY_NOTIFIER); - } + mutex_unlock(&cooling_cpufreq_lock); thermal_cooling_device_unregister(cpufreq_dev->cool_dev); release_idr(&cpufreq_idr, cpufreq_dev->id); kfree(cpufreq_dev); } -EXPORT_SYMBOL(cpufreq_cooling_unregister); +EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister); |