ARM: EXYNOS: Fix CPU idle clock down after CPU off

On Exynos4 USE_DELAYED_RESET_ASSERTION must be set in
ARM_COREx_OPTION register during CPU power down. This is the proper way
of powering down CPU on Exynos4.

Additionally on Exynos4212 without this the CPU clock down feature won't
work after powering down some CPU and the online CPUs will work at full
frequency chosen by CPUfreq governor.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

1 files changed, 41 insertions, 2 deletions

diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index 5d277924ef77..9c6dd1451136 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -34,8 +34,32 @@
 
 extern void exynos4_secondary_startup(void);
 
+/*
+ * Set or clear the USE_DELAYED_RESET_ASSERTION option, set on Exynos4 SoCs
+ * during hot-(un)plugging CPUx.
+ *
+ * The feature can be cleared safely during first boot of secondary CPU.
+ *
+ * Exynos4 SoCs require setting USE_DELAYED_RESET_ASSERTION during powering
+ * down a CPU so the CPU idle clock down feature could properly detect global
+ * idle state when CPUx is off.
+ */
+static void exynos_set_delayed_reset_assertion(u32 core_id, bool enable)
+{
+	if (soc_is_exynos4()) {
+		unsigned int tmp;
+
+		tmp = pmu_raw_readl(EXYNOS_ARM_CORE_OPTION(core_id));
+		if (enable)
+			tmp |= S5P_USE_DELAYED_RESET_ASSERTION;
+		else
+			tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION);
+		pmu_raw_writel(tmp, EXYNOS_ARM_CORE_OPTION(core_id));
+	}
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
-static inline void cpu_leave_lowpower(void)
+static inline void cpu_leave_lowpower(u32 core_id)
 {
 	unsigned int v;
 
@@ -49,6 +73,8 @@ static inline void cpu_leave_lowpower(void)
 	  : "=&r" (v)
 	  : "Ir" (CR_C), "Ir" (0x40)
 	  : "cc");
+
+	 exynos_set_delayed_reset_assertion(core_id, false);
 }
 
 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
@@ -61,6 +87,14 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
 		/* Turn the CPU off on next WFI instruction. */
 		exynos_cpu_power_down(core_id);
 
+		/*
+		 * Exynos4 SoCs require setting
+		 * USE_DELAYED_RESET_ASSERTION so the CPU idle
+		 * clock down feature could properly detect
+		 * global idle state when CPUx is off.
+		 */
+		exynos_set_delayed_reset_assertion(core_id, true);
+
 		wfi();
 
 		if (pen_release == core_id) {
@@ -286,6 +320,9 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
 		udelay(10);
 	}
 
+	/* No harm if this is called during first boot of secondary CPU */
+	exynos_set_delayed_reset_assertion(core_id, false);
+
 	/*
 	 * now the secondary core is starting up let it run its
 	 * calibrations, then wait for it to finish
@@ -376,6 +413,8 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
 static void exynos_cpu_die(unsigned int cpu)
 {
 	int spurious = 0;
+	u32 mpidr = cpu_logical_map(cpu);
+	u32 core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 
 	v7_exit_coherency_flush(louis);
 
@@ -385,7 +424,7 @@ static void exynos_cpu_die(unsigned int cpu)
 	 * bring this CPU back into the world of cache
 	 * coherency, and then restore interrupts
 	 */
-	cpu_leave_lowpower();
+	cpu_leave_lowpower(core_id);
 
 	if (spurious)
 		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);