diff options
Diffstat (limited to 'drivers/cpufreq/cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 164 |
1 files changed, 141 insertions, 23 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index e93405f0eac4..a48b998b3304 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -78,6 +78,11 @@ static int cpufreq_governor(struct cpufreq_policy *policy, unsigned int event); static unsigned int __cpufreq_get(struct cpufreq_policy *policy); static int cpufreq_start_governor(struct cpufreq_policy *policy); +static inline int cpufreq_exit_governor(struct cpufreq_policy *policy) +{ + return cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); +} + /** * Two notifier lists: the "policy" list is involved in the * validation process for a new CPU frequency policy; the @@ -429,6 +434,73 @@ void cpufreq_freq_transition_end(struct cpufreq_policy *policy, } EXPORT_SYMBOL_GPL(cpufreq_freq_transition_end); +/* + * Fast frequency switching status count. Positive means "enabled", negative + * means "disabled" and 0 means "not decided yet". + */ +static int cpufreq_fast_switch_count; +static DEFINE_MUTEX(cpufreq_fast_switch_lock); + +static void cpufreq_list_transition_notifiers(void) +{ + struct notifier_block *nb; + + pr_info("Registered transition notifiers:\n"); + + mutex_lock(&cpufreq_transition_notifier_list.mutex); + + for (nb = cpufreq_transition_notifier_list.head; nb; nb = nb->next) + pr_info("%pF\n", nb->notifier_call); + + mutex_unlock(&cpufreq_transition_notifier_list.mutex); +} + +/** + * cpufreq_enable_fast_switch - Enable fast frequency switching for policy. + * @policy: cpufreq policy to enable fast frequency switching for. + * + * Try to enable fast frequency switching for @policy. + * + * The attempt will fail if there is at least one transition notifier registered + * at this point, as fast frequency switching is quite fundamentally at odds + * with transition notifiers. Thus if successful, it will make registration of + * transition notifiers fail going forward. + */ +void cpufreq_enable_fast_switch(struct cpufreq_policy *policy) +{ + lockdep_assert_held(&policy->rwsem); + + if (!policy->fast_switch_possible) + return; + + mutex_lock(&cpufreq_fast_switch_lock); + if (cpufreq_fast_switch_count >= 0) { + cpufreq_fast_switch_count++; + policy->fast_switch_enabled = true; + } else { + pr_warn("CPU%u: Fast frequency switching not enabled\n", + policy->cpu); + cpufreq_list_transition_notifiers(); + } + mutex_unlock(&cpufreq_fast_switch_lock); +} +EXPORT_SYMBOL_GPL(cpufreq_enable_fast_switch); + +/** + * cpufreq_disable_fast_switch - Disable fast frequency switching for policy. + * @policy: cpufreq policy to disable fast frequency switching for. + */ +void cpufreq_disable_fast_switch(struct cpufreq_policy *policy) +{ + mutex_lock(&cpufreq_fast_switch_lock); + if (policy->fast_switch_enabled) { + policy->fast_switch_enabled = false; + if (!WARN_ON(cpufreq_fast_switch_count <= 0)) + cpufreq_fast_switch_count--; + } + mutex_unlock(&cpufreq_fast_switch_lock); +} +EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch); /********************************************************************* * SYSFS INTERFACE * @@ -1248,26 +1320,24 @@ out_free_policy: */ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) { + struct cpufreq_policy *policy; unsigned cpu = dev->id; - int ret; dev_dbg(dev, "%s: adding CPU%u\n", __func__, cpu); - if (cpu_online(cpu)) { - ret = cpufreq_online(cpu); - } else { - /* - * A hotplug notifier will follow and we will handle it as CPU - * online then. For now, just create the sysfs link, unless - * there is no policy or the link is already present. - */ - struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu); + if (cpu_online(cpu)) + return cpufreq_online(cpu); - ret = policy && !cpumask_test_and_set_cpu(cpu, policy->real_cpus) - ? add_cpu_dev_symlink(policy, cpu) : 0; - } + /* + * A hotplug notifier will follow and we will handle it as CPU online + * then. For now, just create the sysfs link, unless there is no policy + * or the link is already present. + */ + policy = per_cpu(cpufreq_cpu_data, cpu); + if (!policy || cpumask_test_and_set_cpu(cpu, policy->real_cpus)) + return 0; - return ret; + return add_cpu_dev_symlink(policy, cpu); } static void cpufreq_offline(unsigned int cpu) @@ -1319,7 +1389,7 @@ static void cpufreq_offline(unsigned int cpu) /* If cpu is last user of policy, free policy */ if (has_target()) { - ret = cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); + ret = cpufreq_exit_governor(policy); if (ret) pr_err("%s: Failed to exit governor\n", __func__); } @@ -1447,8 +1517,12 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy) ret_freq = cpufreq_driver->get(policy->cpu); - /* Updating inactive policies is invalid, so avoid doing that. */ - if (unlikely(policy_is_inactive(policy))) + /* + * Updating inactive policies is invalid, so avoid doing that. Also + * if fast frequency switching is used with the given policy, the check + * against policy->cur is pointless, so skip it in that case too. + */ + if (unlikely(policy_is_inactive(policy)) || policy->fast_switch_enabled) return ret_freq; if (ret_freq && policy->cur && @@ -1675,8 +1749,18 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list) switch (list) { case CPUFREQ_TRANSITION_NOTIFIER: + mutex_lock(&cpufreq_fast_switch_lock); + + if (cpufreq_fast_switch_count > 0) { + mutex_unlock(&cpufreq_fast_switch_lock); + return -EBUSY; + } ret = srcu_notifier_chain_register( &cpufreq_transition_notifier_list, nb); + if (!ret) + cpufreq_fast_switch_count--; + + mutex_unlock(&cpufreq_fast_switch_lock); break; case CPUFREQ_POLICY_NOTIFIER: ret = blocking_notifier_chain_register( @@ -1709,8 +1793,14 @@ int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list) switch (list) { case CPUFREQ_TRANSITION_NOTIFIER: + mutex_lock(&cpufreq_fast_switch_lock); + ret = srcu_notifier_chain_unregister( &cpufreq_transition_notifier_list, nb); + if (!ret && !WARN_ON(cpufreq_fast_switch_count >= 0)) + cpufreq_fast_switch_count++; + + mutex_unlock(&cpufreq_fast_switch_lock); break; case CPUFREQ_POLICY_NOTIFIER: ret = blocking_notifier_chain_unregister( @@ -1729,6 +1819,37 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier); * GOVERNORS * *********************************************************************/ +/** + * cpufreq_driver_fast_switch - Carry out a fast CPU frequency switch. + * @policy: cpufreq policy to switch the frequency for. + * @target_freq: New frequency to set (may be approximate). + * + * Carry out a fast frequency switch without sleeping. + * + * The driver's ->fast_switch() callback invoked by this function must be + * suitable for being called from within RCU-sched read-side critical sections + * and it is expected to select the minimum available frequency greater than or + * equal to @target_freq (CPUFREQ_RELATION_L). + * + * This function must not be called if policy->fast_switch_enabled is unset. + * + * Governors calling this function must guarantee that it will never be invoked + * twice in parallel for the same policy and that it will never be called in + * parallel with either ->target() or ->target_index() for the same policy. + * + * If CPUFREQ_ENTRY_INVALID is returned by the driver's ->fast_switch() + * callback to indicate an error condition, the hardware configuration must be + * preserved. + */ +unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + clamp_val(target_freq, policy->min, policy->max); + + return cpufreq_driver->fast_switch(policy, target_freq); +} +EXPORT_SYMBOL_GPL(cpufreq_driver_fast_switch); + /* Must set freqs->new to intermediate frequency */ static int __target_intermediate(struct cpufreq_policy *policy, struct cpufreq_freqs *freqs, int index) @@ -2104,7 +2225,7 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, return ret; } - ret = cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); + ret = cpufreq_exit_governor(policy); if (ret) { pr_err("%s: Failed to Exit Governor: %s (%d)\n", __func__, old_gov->name, ret); @@ -2121,7 +2242,7 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, pr_debug("cpufreq: governor change\n"); return 0; } - cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); + cpufreq_exit_governor(policy); } /* new governor failed, so re-start old one */ @@ -2189,16 +2310,13 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb, switch (action & ~CPU_TASKS_FROZEN) { case CPU_ONLINE: + case CPU_DOWN_FAILED: cpufreq_online(cpu); break; case CPU_DOWN_PREPARE: cpufreq_offline(cpu); break; - - case CPU_DOWN_FAILED: - cpufreq_online(cpu); - break; } return NOTIFY_OK; } |