cpufreq: Add boost frequency support in core

This commit adds boost frequency support in cpufreq core (Hardware &
Software). Some SoCs (like Exynos4 - e.g. 4x12) allow setting frequency
above its normal operation limits. Such mode shall be only used for a
short time.

Overclocking (boost) support is essentially provided by platform
dependent cpufreq driver.

This commit unifies support for SW and HW (Intel) overclocking solutions
in the core cpufreq driver. Previously the "boost" sysfs attribute was
defined in the ACPI processor driver code. By default boost is disabled.
One global attribute is available at: /sys/devices/system/cpu/cpufreq/boost.

It only shows up when cpufreq driver supports overclocking.
Under the hood frequencies dedicated for boosting are marked with a
special flag (CPUFREQ_BOOST_FREQ) at driver's frequency table.
It is the user's concern to enable/disable overclocking with a proper call
to sysfs.

The cpufreq_boost_trigger_state() function is defined non static on purpose.
It is used later with thermal subsystem to provide automatic enable/disable
of the BOOST feature.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 117 insertions, 1 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index d7efdfe0c12c..08ca8c9f41cd 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -352,6 +352,33 @@ EXPORT_SYMBOL_GPL(cpufreq_notify_post_transition);
 /*********************************************************************
  *                          SYSFS INTERFACE                          *
  *********************************************************************/
+ssize_t show_boost(struct kobject *kobj,
+				 struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", cpufreq_driver->boost_enabled);
+}
+
+static ssize_t store_boost(struct kobject *kobj, struct attribute *attr,
+				  const char *buf, size_t count)
+{
+	int ret, enable;
+
+	ret = sscanf(buf, "%d", &enable);
+	if (ret != 1 || enable < 0 || enable > 1)
+		return -EINVAL;
+
+	if (cpufreq_boost_trigger_state(enable)) {
+		pr_err("%s: Cannot %s BOOST!\n", __func__,
+		       enable ? "enable" : "disable");
+		return -EINVAL;
+	}
+
+	pr_debug("%s: cpufreq BOOST %s\n", __func__,
+		 enable ? "enabled" : "disabled");
+
+	return count;
+}
+define_one_global_rw(boost);
 
 static struct cpufreq_governor *__find_governor(const char *str_governor)
 {
@@ -2184,6 +2211,73 @@ static struct notifier_block __refdata cpufreq_cpu_notifier = {
 };
 
 /*********************************************************************
+ *               BOOST						     *
+ *********************************************************************/
+static int cpufreq_boost_set_sw(int state)
+{
+	struct cpufreq_frequency_table *freq_table;
+	struct cpufreq_policy *policy;
+	int ret = -EINVAL;
+
+	list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
+		freq_table = cpufreq_frequency_get_table(policy->cpu);
+		if (freq_table) {
+			ret = cpufreq_frequency_table_cpuinfo(policy,
+							freq_table);
+			if (ret) {
+				pr_err("%s: Policy frequency update failed\n",
+				       __func__);
+				break;
+			}
+			policy->user_policy.max = policy->max;
+			__cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
+		}
+	}
+
+	return ret;
+}
+
+int cpufreq_boost_trigger_state(int state)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	if (cpufreq_driver->boost_enabled == state)
+		return 0;
+
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	cpufreq_driver->boost_enabled = state;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	ret = cpufreq_driver->set_boost(state);
+	if (ret) {
+		write_lock_irqsave(&cpufreq_driver_lock, flags);
+		cpufreq_driver->boost_enabled = !state;
+		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+		pr_err("%s: Cannot %s BOOST\n", __func__,
+		       state ? "enable" : "disable");
+	}
+
+	return ret;
+}
+
+int cpufreq_boost_supported(void)
+{
+	if (likely(cpufreq_driver))
+		return cpufreq_driver->boost_supported;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_boost_supported);
+
+int cpufreq_boost_enabled(void)
+{
+	return cpufreq_driver->boost_enabled;
+}
+EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
+
+/*********************************************************************
  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
  *********************************************************************/
 
@@ -2223,9 +2317,25 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	cpufreq_driver = driver_data;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
+	if (cpufreq_boost_supported()) {
+		/*
+		 * Check if driver provides function to enable boost -
+		 * if not, use cpufreq_boost_set_sw as default
+		 */
+		if (!cpufreq_driver->set_boost)
+			cpufreq_driver->set_boost = cpufreq_boost_set_sw;
+
+		ret = cpufreq_sysfs_create_file(&boost.attr);
+		if (ret) {
+			pr_err("%s: cannot register global BOOST sysfs file\n",
+				__func__);
+			goto err_null_driver;
+		}
+	}
+
 	ret = subsys_interface_register(&cpufreq_interface);
 	if (ret)
-		goto err_null_driver;
+		goto err_boost_unreg;
 
 	if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
 		int i;
@@ -2252,6 +2362,9 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	return 0;
 err_if_unreg:
 	subsys_interface_unregister(&cpufreq_interface);
+err_boost_unreg:
+	if (cpufreq_boost_supported())
+		cpufreq_sysfs_remove_file(&boost.attr);
 err_null_driver:
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	cpufreq_driver = NULL;
@@ -2278,6 +2391,9 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 	pr_debug("unregistering driver %s\n", driver->name);
 
 	subsys_interface_unregister(&cpufreq_interface);
+	if (cpufreq_boost_supported())
+		cpufreq_sysfs_remove_file(&boost.attr);
+
 	unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
 
 	down_write(&cpufreq_rwsem);