ARM: tegra30: cpuidle: add powered-down state for secondary CPUs

This supports power-gated idle on secondary CPUs for Tegra30. The
secondary CPUs can go into powered-down state independently. When
CPU goes into this state, it saves it's contexts and puts itself
to flow controlled WFI state. After that, it will been power gated.

Be aware of that, you may see the legacy power state "LP2" in the
code which is exactly the same meaning of "CPU power down".

Based on the work by:
Scott Williams <scwilliams@nvidia.com>

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/cpuidle-tegra30.c b/arch/arm/mach-tegra/cpuidle-tegra30.c
index 37e75512f697..cc48d7fa3358 100644
--- a/arch/arm/mach-tegra/cpuidle-tegra30.c
+++ b/arch/arm/mach-tegra/cpuidle-tegra30.c
@@ -22,21 +22,107 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/cpuidle.h>
+#include <linux/cpu_pm.h>
+#include <linux/clockchips.h>
 
 #include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+#include <asm/suspend.h>
+#include <asm/smp_plat.h>
+
+#include "pm.h"
+#include "sleep.h"
+
+#ifdef CONFIG_PM_SLEEP
+static int tegra30_idle_lp2(struct cpuidle_device *dev,
+			    struct cpuidle_driver *drv,
+			    int index);
+#endif
 
 static struct cpuidle_driver tegra_idle_driver = {
 	.name = "tegra_idle",
 	.owner = THIS_MODULE,
 	.en_core_tk_irqen = 1,
+#ifdef CONFIG_PM_SLEEP
+	.state_count = 2,
+#else
 	.state_count = 1,
+#endif
 	.states = {
 		[0] = ARM_CPUIDLE_WFI_STATE_PWR(600),
+#ifdef CONFIG_PM_SLEEP
+		[1] = {
+			.enter			= tegra30_idle_lp2,
+			.exit_latency		= 2000,
+			.target_residency	= 2200,
+			.power_usage		= 0,
+			.flags			= CPUIDLE_FLAG_TIME_VALID,
+			.name			= "powered-down",
+			.desc			= "CPU power gated",
+		},
+#endif
 	},
 };
 
 static DEFINE_PER_CPU(struct cpuidle_device, tegra_idle_device);
 
+#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_SMP
+static bool tegra30_cpu_core_power_down(struct cpuidle_device *dev,
+					struct cpuidle_driver *drv,
+					int index)
+{
+	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
+
+	smp_wmb();
+
+	save_cpu_arch_register();
+
+	cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
+
+	restore_cpu_arch_register();
+
+	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
+
+	return true;
+}
+#else
+static inline bool tegra30_cpu_core_power_down(struct cpuidle_device *dev,
+					       struct cpuidle_driver *drv,
+					       int index)
+{
+	return true;
+}
+#endif
+
+static int __cpuinit tegra30_idle_lp2(struct cpuidle_device *dev,
+				      struct cpuidle_driver *drv,
+				      int index)
+{
+	u32 cpu = is_smp() ? cpu_logical_map(dev->cpu) : dev->cpu;
+	bool entered_lp2 = false;
+
+	local_fiq_disable();
+
+	tegra_set_cpu_in_lp2(cpu);
+	cpu_pm_enter();
+
+	if (cpu == 0)
+		cpu_do_idle();
+	else
+		entered_lp2 = tegra30_cpu_core_power_down(dev, drv, index);
+
+	cpu_pm_exit();
+	tegra_clear_cpu_in_lp2(cpu);
+
+	local_fiq_enable();
+
+	smp_rmb();
+
+	return (entered_lp2) ? index : 0;
+}
+#endif
+
 int __init tegra30_cpuidle_init(void)
 {
 	int ret;