From e3c06236087051d5c62d60d0668588c370fda887 Mon Sep 17 00:00:00 2001 From: Steve Muckle Date: Wed, 13 Jul 2016 13:25:25 -0700 Subject: [PATCH] cpufreq: add cpufreq_driver_resolve_freq() Cpufreq governors may need to know what a particular target frequency maps to in the driver without necessarily wanting to set the frequency. Support this operation via a new cpufreq API, cpufreq_driver_resolve_freq(). This API returns the lowest driver frequency equal or greater than the target frequency (CPUFREQ_RELATION_L), subject to any policy (min/max) or driver limitations. The mapping is also cached in the policy so that a subsequent fast_switch operation can avoid repeating the same lookup. The API will call a new cpufreq driver callback, resolve_freq(), if it has been registered by the driver. Otherwise the frequency is resolved via cpufreq_frequency_table_target(). Rather than require ->target() style drivers to provide a resolve_freq() callback it is left to the caller to ensure that the driver implements this callback if necessary to use cpufreq_driver_resolve_freq(). Suggested-by: Rafael J. Wysocki Signed-off-by: Steve Muckle Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 25 +++++++++++++++++++++++++ include/linux/cpufreq.h | 16 ++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 118b4f30a406..b696baeb249d 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -492,6 +492,29 @@ void cpufreq_disable_fast_switch(struct cpufreq_policy *policy) } EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch); +/** + * cpufreq_driver_resolve_freq - Map a target frequency to a driver-supported + * one. + * @target_freq: target frequency to resolve. + * + * The target to driver frequency mapping is cached in the policy. + * + * Return: Lowest driver-supported frequency greater than or equal to the + * given target_freq, subject to policy (min/max) and driver limitations. + */ +unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + target_freq = clamp_val(target_freq, policy->min, policy->max); + policy->cached_target_freq = target_freq; + if (cpufreq_driver->resolve_freq) + return cpufreq_driver->resolve_freq(policy, target_freq); + policy->cached_resolved_idx = + cpufreq_frequency_table_target(policy, target_freq, + CPUFREQ_RELATION_L); + return policy->freq_table[policy->cached_resolved_idx].frequency; +} + /********************************************************************* * SYSFS INTERFACE * *********************************************************************/ @@ -2199,6 +2222,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, policy->min = new_policy->min; policy->max = new_policy->max; + policy->cached_target_freq = UINT_MAX; + pr_debug("new min and max freqs are %u - %u kHz\n", policy->min, policy->max); diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index c6410b1b2490..631ba33bbe9f 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -120,6 +120,10 @@ struct cpufreq_policy { bool fast_switch_possible; bool fast_switch_enabled; + /* Cached frequency lookup from cpufreq_driver_resolve_freq. */ + unsigned int cached_target_freq; + int cached_resolved_idx; + /* Synchronization for frequency transitions */ bool transition_ongoing; /* Tracks transition status */ spinlock_t transition_lock; @@ -270,6 +274,16 @@ struct cpufreq_driver { unsigned int index); unsigned int (*fast_switch)(struct cpufreq_policy *policy, unsigned int target_freq); + + /* + * Caches and returns the lowest driver-supported frequency greater than + * or equal to the target frequency, subject to any driver limitations. + * Does not set the frequency. Only to be implemented for drivers with + * target(). + */ + unsigned int (*resolve_freq)(struct cpufreq_policy *policy, + unsigned int target_freq); + /* * Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION * unset. @@ -501,6 +515,8 @@ int cpufreq_driver_target(struct cpufreq_policy *policy, int __cpufreq_driver_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation); +unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy, + unsigned int target_freq); int cpufreq_register_governor(struct cpufreq_governor *governor); void cpufreq_unregister_governor(struct cpufreq_governor *governor); -- 2.20.1