ARM: tegra: Make CPU thermal throttling configurable

Based on work by Dmitriy Gruzman and Varun Wadekar.

Change-Id: I64d765628223b7ef1ec493b9e409ea11e9391b94
Signed-off-by: Todd Poynor <toddpoynor@google.com>

2 files changed, 154 insertions, 131 deletions

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index d351811d9551..983297dfa25e 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -96,3 +96,10 @@ config TEGRA_IOVMM
 
 config TEGRA_ARB_SEMAPHORE
 	bool
+
+config TEGRA_THERMAL_THROTTLE
+       bool "Enable throttling of CPU speed on overtemp"
+       depends on CPU_FREQ
+       default y
+       help
+         Also requires enabling a temperature sensor such as NCT1008.
diff --git a/arch/arm/mach-tegra/cpu-tegra.c b/arch/arm/mach-tegra/cpu-tegra.c
index d8c103e8964c..eddd1b7fabf4 100644
--- a/arch/arm/mach-tegra/cpu-tegra.c
+++ b/arch/arm/mach-tegra/cpu-tegra.c
@@ -50,27 +50,146 @@ static struct cpufreq_frequency_table freq_table[] = {
 	{ 8, CPUFREQ_TABLE_END },
 };
 
-/* CPU frequency is gradually lowered when throttling is enabled */
-#define THROTTLE_START_INDEX	2
-#define THROTTLE_END_INDEX	6
-#define THROTTLE_DELAY		msecs_to_jiffies(2000)
-#define NO_DELAY		msecs_to_jiffies(0)
-
 #define NUM_CPUS	2
 
 static struct clk *cpu_clk;
 static struct clk *emc_clk;
 
-static struct workqueue_struct *workqueue;
-
 static unsigned long target_cpu_speed[NUM_CPUS];
 static DEFINE_MUTEX(tegra_cpu_lock);
 static bool is_suspended;
 
+unsigned int tegra_getspeed(unsigned int cpu);
+static int tegra_update_cpu_speed(unsigned long rate);
+
+/* CPU frequency is gradually lowered when throttling is enabled */
+#define THROTTLE_START_INDEX	2
+#define THROTTLE_END_INDEX	6
+
+#ifdef CONFIG_TEGRA_THERMAL_THROTTLE
+#define THROTTLE_DELAY		msecs_to_jiffies(2000)
+#define NO_DELAY		msecs_to_jiffies(0)
+
 static DEFINE_MUTEX(throttling_lock);
 static bool is_throttling;
 static struct delayed_work throttle_work;
+static struct workqueue_struct *workqueue;
+
+#define tegra_cpu_is_throttling() (is_throttling)
+
+static bool tegra_throttling_needed(unsigned long *rate)
+{
+	unsigned int current_freq = tegra_getspeed(0);
+	int i;
+
+	for (i = THROTTLE_END_INDEX; i >= THROTTLE_START_INDEX; i--) {
+		if (freq_table[i].frequency < current_freq) {
+			*rate = freq_table[i].frequency;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static void tegra_throttle_work_func(struct work_struct *work)
+{
+	unsigned long rate;
+
+	mutex_lock(&tegra_cpu_lock);
+
+	if (tegra_throttling_needed(&rate) && tegra_update_cpu_speed(rate) == 0) {
+		queue_delayed_work(workqueue, &throttle_work, THROTTLE_DELAY);
+	}
+
+	mutex_unlock(&tegra_cpu_lock);
+}
+
+/**
+ * tegra_throttling_enable
+ * This function may sleep
+ */
+void tegra_throttling_enable(void)
+{
+	mutex_lock(&throttling_lock);
+
+	if (!is_throttling) {
+		is_throttling = true;
+		queue_delayed_work(workqueue, &throttle_work, NO_DELAY);
+	}
+
+	mutex_unlock(&throttling_lock);
+}
+EXPORT_SYMBOL_GPL(tegra_throttling_enable);
+
+/**
+ * tegra_throttling_disable
+ * This function may sleep
+ */
+void tegra_throttling_disable(void)
+{
+	mutex_lock(&throttling_lock);
+
+	if (is_throttling) {
+		cancel_delayed_work_sync(&throttle_work);
+		is_throttling = false;
+	}
 
+	mutex_unlock(&throttling_lock);
+}
+EXPORT_SYMBOL_GPL(tegra_throttling_disable);
+
+#ifdef CONFIG_DEBUG_FS
+static int throttle_debug_set(void *data, u64 val)
+{
+	if (val) {
+		tegra_throttling_enable();
+	} else {
+		tegra_throttling_disable();
+	}
+
+	return 0;
+}
+static int throttle_debug_get(void *data, u64 *val)
+{
+	*val = (u64) is_throttling;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(throttle_fops, throttle_debug_get, throttle_debug_set, "%llu\n");
+
+static struct dentry *cpu_tegra_debugfs_root;
+
+static int __init tegra_cpu_debug_init(void)
+{
+	cpu_tegra_debugfs_root = debugfs_create_dir("cpu-tegra", 0);
+
+	if (!cpu_tegra_debugfs_root)
+		return -ENOMEM;
+
+	if (!debugfs_create_file("throttle", 0644, cpu_tegra_debugfs_root, NULL, &throttle_fops))
+		goto err_out;
+
+	return 0;
+
+err_out:
+	debugfs_remove_recursive(cpu_tegra_debugfs_root);
+	return -ENOMEM;
+
+}
+
+static void __exit tegra_cpu_debug_exit(void)
+{
+	debugfs_remove_recursive(cpu_tegra_debugfs_root);
+}
+
+late_initcall(tegra_cpu_debug_init);
+module_exit(tegra_cpu_debug_exit);
+#endif /* CONFIG_DEBUG_FS */
+
+#else /* CONFIG_TEGRA_THERMAL_THROTTLE */
+#define tegra_cpu_is_throttling() (0)
+#endif /* CONFIG_TEGRA_THERMAL_THROTTLE */
 
 int tegra_verify_speed(struct cpufreq_policy *policy)
 {
@@ -169,8 +288,7 @@ static int tegra_target(struct cpufreq_policy *policy,
 {
 	int idx;
 	unsigned int freq;
-	unsigned int highest_speed;
-	unsigned int limit_when_throttling;
+	unsigned int new_speed;
 	int ret = 0;
 
 	mutex_lock(&tegra_cpu_lock);
@@ -187,136 +305,30 @@ static int tegra_target(struct cpufreq_policy *policy,
 
 	target_cpu_speed[policy->cpu] = freq;
 
-	highest_speed = tegra_cpu_highest_speed();
+	new_speed = tegra_cpu_highest_speed();
 
 	/* Do not go above this frequency when throttling */
-	limit_when_throttling = freq_table[THROTTLE_START_INDEX].frequency;
-
-	if (is_throttling && highest_speed > limit_when_throttling) {
-		if (tegra_getspeed(0) < limit_when_throttling) {
-			ret = tegra_update_cpu_speed(limit_when_throttling);
-			goto out;
-		} else {
-			ret = -EBUSY;
-			goto out;
+
+	if (tegra_cpu_is_throttling()) {
+		unsigned int throttle_limit =
+			freq_table[THROTTLE_START_INDEX].frequency;
+
+		if (new_speed > throttle_limit) {
+			if (tegra_getspeed(0) < throttle_limit) {
+				new_speed = throttle_limit;
+			} else {
+				ret = -EBUSY;
+				goto out;
+			}
 		}
 	}
 
-	ret = tegra_update_cpu_speed(highest_speed);
+	ret = tegra_update_cpu_speed(new_speed);
 out:
 	mutex_unlock(&tegra_cpu_lock);
 	return ret;
 }
 
-static bool tegra_throttling_needed(unsigned long *rate)
-{
-	unsigned int current_freq = tegra_getspeed(0);
-	int i;
-
-	for (i = THROTTLE_END_INDEX; i >= THROTTLE_START_INDEX; i--) {
-		if (freq_table[i].frequency < current_freq) {
-			*rate = freq_table[i].frequency;
-			return true;
-		}
-	}
-
-	return false;
-}
-
-static void tegra_throttle_work_func(struct work_struct *work)
-{
-	unsigned long rate;
-
-	mutex_lock(&tegra_cpu_lock);
-
-	if (tegra_throttling_needed(&rate) && tegra_update_cpu_speed(rate) == 0) {
-		queue_delayed_work(workqueue, &throttle_work, THROTTLE_DELAY);
-	}
-
-	mutex_unlock(&tegra_cpu_lock);
-}
-
-/**
- * tegra_throttling_enable
- * This functions may sleep
- */
-void tegra_throttling_enable(void)
-{
-	mutex_lock(&throttling_lock);
-
-	if (!is_throttling) {
-		is_throttling = true;
-		queue_delayed_work(workqueue, &throttle_work, NO_DELAY);
-	}
-
-	mutex_unlock(&throttling_lock);
-}
-EXPORT_SYMBOL_GPL(tegra_throttling_enable);
-
-/**
- * tegra_throttling_disable
- * This functions may sleep
- */
-void tegra_throttling_disable(void)
-{
-	mutex_lock(&throttling_lock);
-
-	if (is_throttling) {
-		cancel_delayed_work_sync(&throttle_work);
-		is_throttling = false;
-	}
-
-	mutex_unlock(&throttling_lock);
-}
-EXPORT_SYMBOL_GPL(tegra_throttling_disable);
-
-#ifdef CONFIG_DEBUG_FS
-static int throttle_debug_set(void *data, u64 val)
-{
-	if (val) {
-		tegra_throttling_enable();
-	} else {
-		tegra_throttling_disable();
-	}
-
-	return 0;
-}
-static int throttle_debug_get(void *data, u64 *val)
-{
-	*val = (u64) is_throttling;
-	return 0;
-}
-
-DEFINE_SIMPLE_ATTRIBUTE(throttle_fops, throttle_debug_get, throttle_debug_set, "%llu\n");
-
-static struct dentry *cpu_tegra_debugfs_root;
-
-static int __init tegra_cpu_debug_init(void)
-{
-	cpu_tegra_debugfs_root = debugfs_create_dir("cpu-tegra", 0);
-
-	if (!cpu_tegra_debugfs_root)
-		return -ENOMEM;
-
-	if (!debugfs_create_file("throttle", 0644, cpu_tegra_debugfs_root, NULL, &throttle_fops))
-		goto err_out;
-
-	return 0;
-
-err_out:
-	debugfs_remove_recursive(cpu_tegra_debugfs_root);
-	return -ENOMEM;
-
-}
-
-static void __exit tegra_cpu_debug_exit(void)
-{
-	debugfs_remove_recursive(cpu_tegra_debugfs_root);
-}
-
-late_initcall(tegra_cpu_debug_init);
-module_exit(tegra_cpu_debug_exit);
-#endif
 
 static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
 	void *dummy)
@@ -367,7 +379,6 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 	cpumask_copy(policy->related_cpus, cpu_possible_mask);
 
 	if (policy->cpu == 0) {
-		INIT_DELAYED_WORK(&throttle_work, tegra_throttle_work_func);
 		register_pm_notifier(&tegra_cpu_pm_notifier);
 	}
 
@@ -400,15 +411,20 @@ static struct cpufreq_driver tegra_cpufreq_driver = {
 
 static int __init tegra_cpufreq_init(void)
 {
+#ifdef CONFIG_TEGRA_THERMAL_THROTTLE
 	workqueue = create_singlethread_workqueue("cpu-tegra");
 	if (!workqueue)
 		return -ENOMEM;
+	INIT_DELAYED_WORK(&throttle_work, tegra_throttle_work_func);
+#endif
 	return cpufreq_register_driver(&tegra_cpufreq_driver);
 }
 
 static void __exit tegra_cpufreq_exit(void)
 {
+#ifdef CONFIG_TEGRA_THERMAL_THROTTLE
 	destroy_workqueue(workqueue);
+#endif
         cpufreq_unregister_driver(&tegra_cpufreq_driver);
 }