ARM: tegra: dvfs: Add cold zone Tegra3 CPU dvfs limits

Added alternative frequency limits for Tegra3 CPU. These limits are
applied only in the lowest CPU EDP temperature zone, and the offset
from regular Tegra3 dvfs frequencies is set at -50MHz at all scaling
voltage steps. Offset values as well as temperature threshold are to
be updated per characterization.

Bug 913884

Change-Id: Ia420f54b4c9fdc966e44d0269d45d9164d751b5f
Signed-off-by: Alex Frid <[email protected]>
Reviewed-on: http://git-master/r/70189
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Diwakar Tundlam <[email protected]>
Tested-by: Diwakar Tundlam <[email protected]>
Reviewed-by: Krishna Reddy <[email protected]>
Reviewed-on: http://git-master/r/75615
Reviewed-by: Varun Wadekar <[email protected]>
Tested-by: Varun Wadekar <[email protected]>

Author: Alex Frid

arch/arm/mach-tegra/cpu-tegra.c

@@ -41,6 +41,7 @@
 
 #include "clock.h"
 #include "cpu-tegra.h"
+#include "dvfs.h"
 
 /* tegra throttling and edp governors require frequencies in the table
    to be in ascending order */
@@ -226,11 +227,14 @@ int tegra_edp_update_thermal_zone(int temperature)
 	mutex_lock(&tegra_cpu_lock);
 	edp_thermal_index = index;
 
-	/* Update cpu rate if cpufreq (at least on cpu0) is already started */
+	/* Update cpu rate if cpufreq (at least on cpu0) is already started;
+	   alter cpu dvfs table for this thermal zone if necessary */
+	tegra_cpu_dvfs_alter(edp_thermal_index, true);
 	if (target_cpu_speed[0]) {
 		edp_update_limit();
 		tegra_cpu_set_speed_cap(NULL);
 	}
+	tegra_cpu_dvfs_alter(edp_thermal_index, false);
 	mutex_unlock(&tegra_cpu_lock);
 
 	return ret;

arch/arm/mach-tegra/dvfs.h

@@ -125,6 +125,7 @@ int tegra_dvfs_predict_millivolts(struct clk *c, unsigned long rate);
 void tegra_dvfs_core_cap_enable(bool enable);
 void tegra_dvfs_core_cap_level_set(int level);
 int tegra_dvfs_alt_freqs_set(struct dvfs *d, bool enable);
+void tegra_cpu_dvfs_alter(int edp_thermal_index, bool before_clk_update);
 #else
 static inline void tegra_soc_init_dvfs(void)
 {}
@@ -161,6 +162,9 @@ static inline void tegra_dvfs_core_cap_level_set(int level)
 {}
 static inline int tegra_dvfs_alt_freqs_set(struct dvfs *d, bool enable)
 { return 0; }
+static inline void tegra_cpu_dvfs_alter(int edp_thermal_index,
+					bool before_clk_update)
+{}
 #endif
 
 #ifndef CONFIG_ARCH_TEGRA_2x_SOC

arch/arm/mach-tegra/tegra3_dvfs.c

@@ -30,10 +30,14 @@
 
 static bool tegra_dvfs_cpu_disabled;
 static bool tegra_dvfs_core_disabled;
+static struct dvfs *cpu_dvfs;
 
 static const int cpu_millivolts[MAX_DVFS_FREQS] = {
 	800, 825, 850, 875, 900, 912, 975, 1000, 1025, 1050, 1075, 1100, 1125, 1150, 1175, 1200, 1212, 1237};
 
+static const unsigned int cpu_cold_offs_mhz[MAX_DVFS_FREQS] = {
+	  50,  50,  50,  50,  50,  50,  50,  50,  50,   50,   50,   50,   50,   50,   50,   50,   50,   50};
+
 static const int core_millivolts[MAX_DVFS_FREQS] =
 	{1000, 1050, 1100, 1150, 1200, 1250, 1300};
 
@@ -422,6 +426,31 @@ static void __init init_dvfs_one(struct dvfs *d, int nominal_mv_index)
 	}
 }
 
+static void __init init_dvfs_cold(struct dvfs *d, int nominal_mv_index)
+{
+	int i;
+	unsigned long offs;
+
+	BUG_ON((nominal_mv_index == 0) || (nominal_mv_index > d->num_freqs));
+
+	for (i = 0; i < d->num_freqs; i++) {
+		offs = cpu_cold_offs_mhz[i] * MHZ;
+		if (i > nominal_mv_index)
+			d->alt_freqs[i] = d->alt_freqs[i - 1];
+		else if (d->freqs[i] > offs)
+			d->alt_freqs[i] = d->freqs[i] - offs;
+		else {
+			d->alt_freqs[i] = d->freqs[i];
+			pr_warn("tegra3_dvfs: cold offset %lu is too high for"
+				" regular dvfs limit %lu\n", offs, d->freqs[i]);
+		}
+
+		if (i)
+			BUG_ON(d->alt_freqs[i] < d->alt_freqs[i - 1]);
+	}
+	d->alt_freqs_state = ALT_FREQS_DISABLED;
+}
+
 static bool __init match_dvfs_one(struct dvfs *d, int speedo_id, int process_id)
 {
 	if ((d->process_id != -1 && d->process_id != process_id) ||
@@ -535,7 +564,6 @@ void __init tegra_soc_init_dvfs(void)
 	int i;
 	int core_nominal_mv_index;
 	int cpu_nominal_mv_index;
-	struct dvfs *cpu_dvfs = NULL;
 
 #ifndef CONFIG_TEGRA_CORE_DVFS
 	tegra_dvfs_core_disabled = true;
@@ -581,6 +609,7 @@ void __init tegra_soc_init_dvfs(void)
 	/* Initialize matching cpu dvfs entry already found when nominal
 	   voltage was determined */
 	init_dvfs_one(cpu_dvfs, cpu_nominal_mv_index);
+	init_dvfs_cold(cpu_dvfs, cpu_nominal_mv_index);
 
 	/* Finally disable dvfs on rails if necessary */
 	if (tegra_dvfs_core_disabled)
@@ -596,6 +625,17 @@ void __init tegra_soc_init_dvfs(void)
 		tegra_dvfs_core_disabled ? "disabled" : "enabled");
 }
 
+void tegra_cpu_dvfs_alter(int edp_thermal_index, bool before_clk_update)
+{
+	bool enable = !edp_thermal_index;
+
+	if (enable != before_clk_update) {
+		int ret = tegra_dvfs_alt_freqs_set(cpu_dvfs, enable);
+		WARN_ONCE(ret, "tegra dvfs: failed to set CPU alternative"
+			       " frequency limits for cold temeperature\n");
+	}
+}
+
 int tegra_dvfs_rail_disable_prepare(struct dvfs_rail *rail)
 {
 	int ret = 0;