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, 148 insertions, 125 deletions

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index da1d392e8f32..053b4cc2541e 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -132,3 +132,10 @@ 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 fcf54ede8542..8e86009b4ac1 100644
--- a/arch/arm/mach-tegra/cpu-tegra.c
+++ b/arch/arm/mach-tegra/cpu-tegra.c
@@ -48,141 +48,32 @@ 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;
 
-static DEFINE_MUTEX(throttling_lock);
-static bool is_throttling;
-static struct delayed_work throttle_work;
-
-
-int tegra_verify_speed(struct cpufreq_policy *policy)
-{
-	return cpufreq_frequency_table_verify(policy, freq_table);
-}
-
-unsigned int tegra_getspeed(unsigned int cpu)
-{
-	unsigned long rate;
-
-	if (cpu >= NUM_CPUS)
-		return 0;
-
-	rate = clk_get_rate(cpu_clk) / 1000;
-	return rate;
-}
-
-static int tegra_update_cpu_speed(unsigned long rate)
-{
-	int ret = 0;
-	struct cpufreq_freqs freqs;
-
-	freqs.old = tegra_getspeed(0);
-	freqs.new = rate;
-
-	if (freqs.old == freqs.new)
-		return ret;
-
-	/*
-	 * Vote on memory bus frequency based on cpu frequency
-	 * This sets the minimum frequency, display or avp may request higher
-	 */
-	if (rate >= 816000)
-		clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
-	else if (rate >= 456000)
-		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
-	else
-		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
-
-	for_each_online_cpu(freqs.cpu)
-		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
-
-#ifdef CONFIG_CPU_FREQ_DEBUG
-	printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
-	       freqs.old, freqs.new);
-#endif
-
-	ret = clk_set_rate(cpu_clk, freqs.new * 1000);
-	if (ret) {
-		pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
-			freqs.new);
-		return ret;
-	}
-
-	for_each_online_cpu(freqs.cpu)
-		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
-
-	return 0;
-}
-
-static unsigned long tegra_cpu_highest_speed(void)
-{
-	unsigned long rate = 0;
-	int i;
-
-	for_each_online_cpu(i)
-		rate = max(rate, target_cpu_speed[i]);
-	return rate;
-}
-
-static int tegra_target(struct cpufreq_policy *policy,
-		       unsigned int target_freq,
-		       unsigned int relation)
-{
-	int idx;
-	unsigned int freq;
-	unsigned int highest_speed;
-	unsigned int limit_when_throttling;
-	int ret = 0;
-
-	mutex_lock(&tegra_cpu_lock);
-
-	if (is_suspended) {
-		ret = -EBUSY;
-		goto out;
-	}
-
-	cpufreq_frequency_table_target(policy, freq_table, target_freq,
-		relation, &idx);
-
-	freq = freq_table[idx].frequency;
+unsigned int tegra_getspeed(unsigned int cpu);
+static int tegra_update_cpu_speed(unsigned long rate);
 
-	target_cpu_speed[policy->cpu] = freq;
+/* CPU frequency is gradually lowered when throttling is enabled */
+#define THROTTLE_START_INDEX	2
+#define THROTTLE_END_INDEX	6
 
-	highest_speed = tegra_cpu_highest_speed();
+#ifdef CONFIG_TEGRA_THERMAL_THROTTLE
+#define THROTTLE_DELAY		msecs_to_jiffies(2000)
+#define NO_DELAY		msecs_to_jiffies(0)
 
-	/* 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;
-		}
-	}
+static DEFINE_MUTEX(throttling_lock);
+static bool is_throttling;
+static struct delayed_work throttle_work;
+static struct workqueue_struct *workqueue;
 
-	ret = tegra_update_cpu_speed(highest_speed);
-out:
-	mutex_unlock(&tegra_cpu_lock);
-	return ret;
-}
+#define tegra_cpu_is_throttling() (is_throttling)
 
 static bool tegra_throttling_needed(unsigned long *rate)
 {
@@ -214,7 +105,7 @@ static void tegra_throttle_work_func(struct work_struct *work)
 
 /**
  * tegra_throttling_enable
- * This functions may sleep
+ * This function may sleep
  */
 void tegra_throttling_enable(void)
 {
@@ -231,7 +122,7 @@ EXPORT_SYMBOL_GPL(tegra_throttling_enable);
 
 /**
  * tegra_throttling_disable
- * This functions may sleep
+ * This function may sleep
  */
 void tegra_throttling_disable(void)
 {
@@ -292,8 +183,129 @@ static void __exit tegra_cpu_debug_exit(void)
 
 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)
+{
+	return cpufreq_frequency_table_verify(policy, freq_table);
+}
+
+unsigned int tegra_getspeed(unsigned int cpu)
+{
+	unsigned long rate;
+
+	if (cpu >= NUM_CPUS)
+		return 0;
+
+	rate = clk_get_rate(cpu_clk) / 1000;
+	return rate;
+}
+
+static int tegra_update_cpu_speed(unsigned long rate)
+{
+	int ret = 0;
+	struct cpufreq_freqs freqs;
+
+	freqs.old = tegra_getspeed(0);
+	freqs.new = rate;
+
+	if (freqs.old == freqs.new)
+		return ret;
+
+	/*
+	 * Vote on memory bus frequency based on cpu frequency
+	 * This sets the minimum frequency, display or avp may request higher
+	 */
+	if (rate >= 816000)
+		clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
+	else if (rate >= 456000)
+		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
+	else
+		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
+
+	for_each_online_cpu(freqs.cpu)
+		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+#ifdef CONFIG_CPU_FREQ_DEBUG
+	printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
+	       freqs.old, freqs.new);
 #endif
 
+	ret = clk_set_rate(cpu_clk, freqs.new * 1000);
+	if (ret) {
+		pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
+			freqs.new);
+		return ret;
+	}
+
+	for_each_online_cpu(freqs.cpu)
+		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return 0;
+}
+
+static unsigned long tegra_cpu_highest_speed(void)
+{
+	unsigned long rate = 0;
+	int i;
+
+	for_each_online_cpu(i)
+		rate = max(rate, target_cpu_speed[i]);
+	return rate;
+}
+
+static int tegra_target(struct cpufreq_policy *policy,
+		       unsigned int target_freq,
+		       unsigned int relation)
+{
+	int idx;
+	unsigned int freq;
+	unsigned int new_speed;
+	int ret = 0;
+
+	mutex_lock(&tegra_cpu_lock);
+
+	if (is_suspended) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	cpufreq_frequency_table_target(policy, freq_table, target_freq,
+		relation, &idx);
+
+	freq = freq_table[idx].frequency;
+
+	target_cpu_speed[policy->cpu] = freq;
+
+	new_speed = tegra_cpu_highest_speed();
+
+	/* Do not go above this frequency when throttling */
+
+	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(new_speed);
+out:
+	mutex_unlock(&tegra_cpu_lock);
+	return ret;
+}
+
+
 static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
 	void *dummy)
 {
@@ -345,7 +357,6 @@ 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);
 	}
 
@@ -378,15 +389,20 @@ 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);
 }