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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-03-30 03:47:49 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-04-02 01:09:03 +0200
commitb7898fda5bc7e786e76ce24fbd2ec993b08ec518 (patch)
tree2bf721763c79a7fe0eca25349a549c52ba6ce483 /include/linux/cpufreq.h
parent379480d8258056bfdbaa65e4d3f024bb5b34b52b (diff)
cpufreq: Support for fast frequency switching
Modify the ACPI cpufreq driver to provide a method for switching CPU frequencies from interrupt context and update the cpufreq core to support that method if available. Introduce a new cpufreq driver callback, ->fast_switch, to be invoked for frequency switching from interrupt context by (future) governors supporting that feature via (new) helper function cpufreq_driver_fast_switch(). Add two new policy flags, fast_switch_possible, to be set by the cpufreq driver if fast frequency switching can be used for the given policy and fast_switch_enabled, to be set by the governor if it is going to use fast frequency switching for the given policy. Also add a helper for setting the latter. Since fast frequency switching is inherently incompatible with cpufreq transition notifiers, make it possible to set the fast_switch_enabled only if there are no transition notifiers already registered and make the registration of new transition notifiers fail if fast_switch_enabled is set for at least one policy. Implement the ->fast_switch callback in the ACPI cpufreq driver and make it set fast_switch_possible during policy initialization as appropriate. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Diffstat (limited to 'include/linux/cpufreq.h')
-rw-r--r--include/linux/cpufreq.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 2b4f248b8ef1..55e69ebb035c 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -102,6 +102,17 @@ struct cpufreq_policy {
*/
struct rw_semaphore rwsem;
+ /*
+ * Fast switch flags:
+ * - fast_switch_possible should be set by the driver if it can
+ * guarantee that frequency can be changed on any CPU sharing the
+ * policy and that the change will affect all of the policy CPUs then.
+ * - fast_switch_enabled is to be set by governors that support fast
+ * freqnency switching with the help of cpufreq_enable_fast_switch().
+ */
+ bool fast_switch_possible;
+ bool fast_switch_enabled;
+
/* Synchronization for frequency transitions */
bool transition_ongoing; /* Tracks transition status */
spinlock_t transition_lock;
@@ -156,6 +167,7 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu);
int cpufreq_update_policy(unsigned int cpu);
bool have_governor_per_policy(void);
struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy);
+void cpufreq_enable_fast_switch(struct cpufreq_policy *policy);
#else
static inline unsigned int cpufreq_get(unsigned int cpu)
{
@@ -236,6 +248,8 @@ struct cpufreq_driver {
unsigned int relation); /* Deprecated */
int (*target_index)(struct cpufreq_policy *policy,
unsigned int index);
+ unsigned int (*fast_switch)(struct cpufreq_policy *policy,
+ unsigned int target_freq);
/*
* Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION
* unset.
@@ -464,6 +478,8 @@ struct cpufreq_governor {
};
/* Pass a target to the cpufreq driver */
+unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
+ unsigned int target_freq);
int cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation);