[PATCH 1/3] ARM: EXYNOS: Move code from hotplug.c to platsmp.c

[PATCH 1/3] ARM: EXYNOS: Move code from hotplug.c to platsmp.c

[Krzysztof Kozlowski]

Cleanup a little the SMP/hotplug code for Exynos by:
1. Moving completely all functions from hotplug.c into the platsmp.c;
2. Deleting the hotplug.c file.

After recent cleanups (e.g. 75ad2ab28f0f "ARM: EXYNOS: use
v7_exit_coherency_flush macro for cache disabling") there was only CPU
power down related code in hotplug.c file. Keeping this file does not
give any benefits.

The commit only moves code around with one additional observable change:
the hotplug.c was compiled with custom CFLAGS (-march=armv7-a). These
CFLAGS are not necessary any more.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
---
 arch/arm/mach-exynos/Makefile  |  3 --
 arch/arm/mach-exynos/common.h  |  2 -
 arch/arm/mach-exynos/hotplug.c | 92 ------------------------------------------
 arch/arm/mach-exynos/platsmp.c | 74 +++++++++++++++++++++++++++++++++
 4 files changed, 74 insertions(+), 97 deletions(-)
 delete mode 100644 arch/arm/mach-exynos/hotplug.c

diff --git a/arch/arm/mach-exynos/Makefile b/arch/arm/mach-exynos/Makefile
index 788f26d21141..0095de99d703 100644
--- a/arch/arm/mach-exynos/Makefile
+++ b/arch/arm/mach-exynos/Makefile
@@ -21,9 +21,6 @@ obj-$(CONFIG_PM_GENERIC_DOMAINS) += pm_domains.o
 
 obj-$(CONFIG_SMP)		+= platsmp.o headsmp.o
 
-obj-$(CONFIG_HOTPLUG_CPU)	+= hotplug.o
-CFLAGS_hotplug.o		+= -march=armv7-a
-
 plus_sec := $(call as-instr,.arch_extension sec,+sec)
 AFLAGS_exynos-smc.o		:=-Wa,-march=armv7-a$(plus_sec)
 
diff --git a/arch/arm/mach-exynos/common.h b/arch/arm/mach-exynos/common.h
index 1ee91763fa7c..907349d20c25 100644
--- a/arch/arm/mach-exynos/common.h
+++ b/arch/arm/mach-exynos/common.h
@@ -141,8 +141,6 @@ extern void exynos_cpu_resume(void);
 
 extern struct smp_operations exynos_smp_ops;
 
-extern void exynos_cpu_die(unsigned int cpu);
-
 /* PMU(Power Management Unit) support */
 
 #define PMU_TABLE_END	NULL
diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
deleted file mode 100644
index 920a4baa53cd..000000000000
--- a/arch/arm/mach-exynos/hotplug.c
+++ /dev/null
@@ -1,92 +0,0 @@
-/* linux arch/arm/mach-exynos4/hotplug.c
- *
- *  Cloned from linux/arch/arm/mach-realview/hotplug.c
- *
- *  Copyright (C) 2002 ARM Ltd.
- *  All Rights Reserved
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
-
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/smp.h>
-#include <linux/io.h>
-
-#include <asm/cacheflush.h>
-#include <asm/cp15.h>
-#include <asm/smp_plat.h>
-
-#include "common.h"
-#include "regs-pmu.h"
-
-static inline void cpu_leave_lowpower(void)
-{
-	unsigned int v;
-
-	asm volatile(
-	"mrc	p15, 0, %0, c1, c0, 0\n"
-	"	orr	%0, %0, %1\n"
-	"	mcr	p15, 0, %0, c1, c0, 0\n"
-	"	mrc	p15, 0, %0, c1, c0, 1\n"
-	"	orr	%0, %0, %2\n"
-	"	mcr	p15, 0, %0, c1, c0, 1\n"
-	  : "=&r" (v)
-	  : "Ir" (CR_C), "Ir" (0x40)
-	  : "cc");
-}
-
-static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
-{
-	u32 mpidr = cpu_logical_map(cpu);
-	u32 core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
-
-	for (;;) {
-
-		/* Turn the CPU off on next WFI instruction. */
-		exynos_cpu_power_down(core_id);
-
-		wfi();
-
-		if (pen_release == core_id) {
-			/*
-			 * OK, proper wakeup, we're done
-			 */
-			break;
-		}
-
-		/*
-		 * Getting here, means that we have come out of WFI without
-		 * having been woken up - this shouldn't happen
-		 *
-		 * Just note it happening - when we're woken, we can report
-		 * its occurrence.
-		 */
-		(*spurious)++;
-	}
-}
-
-/*
- * platform-specific code to shutdown a CPU
- *
- * Called with IRQs disabled
- */
-void __ref exynos_cpu_die(unsigned int cpu)
-{
-	int spurious = 0;
-
-	v7_exit_coherency_flush(louis);
-
-	platform_do_lowpower(cpu, &spurious);
-
-	/*
-	 * bring this CPU back into the world of cache
-	 * coherency, and then restore interrupts
-	 */
-	cpu_leave_lowpower();
-
-	if (spurious)
-		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
-}
diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index 50b9aad5e27b..b0679b6d5161 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -23,6 +23,7 @@
 #include <linux/of_address.h>
 
 #include <asm/cacheflush.h>
+#include <asm/cp15.h>
 #include <asm/smp_plat.h>
 #include <asm/smp_scu.h>
 #include <asm/firmware.h>
@@ -32,6 +33,54 @@
 
 extern void exynos4_secondary_startup(void);
 
+#ifdef CONFIG_HOTPLUG_CPU
+static inline void cpu_leave_lowpower(void)
+{
+	unsigned int v;
+
+	asm volatile(
+	"mrc	p15, 0, %0, c1, c0, 0\n"
+	"	orr	%0, %0, %1\n"
+	"	mcr	p15, 0, %0, c1, c0, 0\n"
+	"	mrc	p15, 0, %0, c1, c0, 1\n"
+	"	orr	%0, %0, %2\n"
+	"	mcr	p15, 0, %0, c1, c0, 1\n"
+	  : "=&r" (v)
+	  : "Ir" (CR_C), "Ir" (0x40)
+	  : "cc");
+}
+
+static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
+{
+	u32 mpidr = cpu_logical_map(cpu);
+	u32 core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+
+	for (;;) {
+
+		/* Turn the CPU off on next WFI instruction. */
+		exynos_cpu_power_down(core_id);
+
+		wfi();
+
+		if (pen_release == core_id) {
+			/*
+			 * OK, proper wakeup, we're done
+			 */
+			break;
+		}
+
+		/*
+		 * Getting here, means that we have come out of WFI without
+		 * having been woken up - this shouldn't happen
+		 *
+		 * Just note it happening - when we're woken, we can report
+		 * its occurrence.
+		 */
+		(*spurious)++;
+	}
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
 static inline void __iomem *cpu_boot_reg_base(void)
 {
 	if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
@@ -251,6 +300,31 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
 	}
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+static void __ref exynos_cpu_die(unsigned int cpu)
+{
+	int spurious = 0;
+
+	v7_exit_coherency_flush(louis);
+
+	platform_do_lowpower(cpu, &spurious);
+
+	/*
+	 * bring this CPU back into the world of cache
+	 * coherency, and then restore interrupts
+	 */
+	cpu_leave_lowpower();
+
+	if (spurious)
+		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
 struct smp_operations exynos_smp_ops __initdata = {
 	.smp_init_cpus		= exynos_smp_init_cpus,
 	.smp_prepare_cpus	= exynos_smp_prepare_cpus,
-- 
1.9.1

[PATCH 2/3] ARM: EXYNOS: Remove unneeded __ref annotation for cpu_die function

[Krzysztof Kozlowski]

The __ref annotation for exynos_cpu_die() is not needed because the
function does not reference any __init/__exit symbol or call.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
---
 arch/arm/mach-exynos/platsmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index b0679b6d5161..6a0de7591f73 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -306,7 +306,7 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
  *
  * Called with IRQs disabled
  */
-static void __ref exynos_cpu_die(unsigned int cpu)
+static void exynos_cpu_die(unsigned int cpu)
 {
 	int spurious = 0;
 
-- 
1.9.1

[PATCH 3/3] ARM: exynos4: hotplug: Fix CPU idle clock down after CPU off

[Krzysztof Kozlowski]

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>

---
Changes since v3:
1. Remove declaration of exynos_clear_delayed_reset_assertion() in
   header as hotplug code is integrated into platsmp.c file. Suggested
   by Tomasz Figa.
2. Replace 'clear' helper with 'set' helper. Suggested by Tomasz Figa.

Changes since v2:
1. Add missing disable of the "use delayed reset assertion" feature
   when starting secondary CPU (suggested by Tomasz Figa).

Changes since v1:
1. Use delayed reset assertion on all Exynos4 family and all cores, not
   only on core 1 of Exynos4212.
2. Rebase on Tomasz Figa's patch:
   ARM: EXYNOS: Fix core ID used by platsmp and hotplug code
   http://www.spinics.net/lists/linux-samsung-soc/msg31604.html
   Tomasz's patch is currently applied to Kukjin's v3.16-samsung-fixes-4
---
 arch/arm/mach-exynos/platsmp.c  | 43 +++++++++++++++++++++++++++++++++++++++--
 arch/arm/mach-exynos/regs-pmu.h |  3 +++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index 6a0de7591f73..393b1a00dbcb 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -33,8 +33,32 @@
 
 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 = __raw_readl(EXYNOS_ARM_CORE_OPTION(core_id));
+		if (enable)
+			tmp |= S5P_USE_DELAYED_RESET_ASSERTION;
+		else
+			tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION);
+		__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;
 
@@ -48,6 +72,8 @@ 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)
@@ -60,6 +86,14 @@ 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) {
@@ -219,6 +253,9 @@ 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
@@ -309,6 +346,8 @@ 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);
 
@@ -318,7 +357,7 @@ 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);
diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
index 1d13b08708f0..59bd92112842 100644
--- a/arch/arm/mach-exynos/regs-pmu.h
+++ b/arch/arm/mach-exynos/regs-pmu.h
@@ -25,6 +25,7 @@
 
 #define S5P_USE_STANDBY_WFI0			(1 << 16)
 #define S5P_USE_STANDBY_WFE0			(1 << 24)
+#define S5P_USE_DELAYED_RESET_ASSERTION		BIT(12)
 
 #define EXYNOS_SWRESET				S5P_PMUREG(0x0400)
 #define EXYNOS5440_SWRESET			S5P_PMUREG(0x00C4)
@@ -111,6 +112,8 @@
 			(EXYNOS_ARM_CORE0_CONFIGURATION + (0x80 * (_nr)))
 #define EXYNOS_ARM_CORE_STATUS(_nr)		\
 			(EXYNOS_ARM_CORE_CONFIGURATION(_nr) + 0x4)
+#define EXYNOS_ARM_CORE_OPTION(_nr)		\
+			(EXYNOS_ARM_CORE_CONFIGURATION(_nr) + 0x8)
 
 #define EXYNOS_ARM_COMMON_CONFIGURATION		S5P_PMUREG(0x2500)
 #define EXYNOS_COMMON_CONFIGURATION(_nr)	\
-- 
1.9.1

Re: [PATCH 1/3] ARM: EXYNOS: Move code from hotplug.c to platsmp.c

[Tomasz Figa]

Hi Krzysztof,

On 16.07.2014 16:20, Krzysztof Kozlowski wrote:
> Cleanup a little the SMP/hotplug code for Exynos by:
> 1. Moving completely all functions from hotplug.c into the platsmp.c;
> 2. Deleting the hotplug.c file.
> 
> After recent cleanups (e.g. 75ad2ab28f0f "ARM: EXYNOS: use
> v7_exit_coherency_flush macro for cache disabling") there was only CPU
> power down related code in hotplug.c file. Keeping this file does not
> give any benefits.
> 
> The commit only moves code around with one additional observable change:
> the hotplug.c was compiled with custom CFLAGS (-march=armv7-a). These
> CFLAGS are not necessary any more.
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> ---
>  arch/arm/mach-exynos/Makefile  |  3 --
>  arch/arm/mach-exynos/common.h  |  2 -
>  arch/arm/mach-exynos/hotplug.c | 92 ------------------------------------------
>  arch/arm/mach-exynos/platsmp.c | 74 +++++++++++++++++++++++++++++++++
>  4 files changed, 74 insertions(+), 97 deletions(-)
>  delete mode 100644 arch/arm/mach-exynos/hotplug.c
> 

For this and remaining patches from this series:

Reviewed-by: Tomasz Figa <t.figa@samsung.com>

--
Best regards,
Tomasz