[PATCH v9] ARM: EXYNOS: Use MCPM call-backs to support S2R on Exynos5420

From: Abhilash Kesavan <a.kesavan@samsung.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org, kgene.kim@samsung.com
Subject: [PATCH v9] ARM: EXYNOS: Use MCPM call-backs to support S2R on Exynos5420
Date: Wed, 08 Oct 2014 11:11:32 +0530	[thread overview]
Message-ID: <1412746892-12329-1-git-send-email-a.kesavan@samsung.com> (raw)

Use the MCPM layer to handle core suspend/resume on Exynos5420.
Also, restore the entry address setup code post-resume.

Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
---
Changes in v2:
	- Made use of the MCPM suspend/powered_up call-backs
Changes in v3:
	- Used the residency value to indicate the entered state
Changes in v4:
	- Checked if MCPM has been enabled to prevent build error
Changes in v5:
	- Removed the MCPM flags and just used a local flag to
	indicate that we are suspending.
Changes in v6:
	- Read the SYS_PWR_REG value to decide if we are suspending
	the system.
	- Restore the SYS_PWR_REG value post-resume.
	- Modified the comments to reflect the first change.
Changes in v7:
	- Add the suspend check in exynos_cpu_power_down() rather
	than the MCPM back-end.
	- Clean-up unnecessary changes related to earlier versions.
Changes in v8:
	- Rebased on the latest exynos PMU/PM support patches.
Changes in v9:
	- Fixed rebasing issues in v8
	- Used pmu_raw_readl instead of __raw_readl

This patch is based on kgene's for-next branch.
http://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/log/?h=for-next

Here are the dependencies:
1) Decouple syscon interface from platform devices - v7
http://lkml.org/lkml/2014/9/30/156

2) ARM: Exynos: Convert PMU implementation into a platform driver - v9
https://lkml.org/lkml/2014/10/6/89

3) Exynos5420 PMU/S2R Series - v9
http://www.spinics.net/lists/arm-kernel/msg368207.html

 arch/arm/mach-exynos/mcpm-exynos.c |   32 +++++++++++++++--------
 arch/arm/mach-exynos/platsmp.c     |   12 +++++++++
 arch/arm/mach-exynos/suspend.c     |   49 ++++++++++++++++++++++++++++++++----
 3 files changed, 78 insertions(+), 15 deletions(-)

diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c
index dc9a764..b0d3c2e 100644
--- a/arch/arm/mach-exynos/mcpm-exynos.c
+++ b/arch/arm/mach-exynos/mcpm-exynos.c
@@ -15,6 +15,7 @@
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/of_address.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/cputype.h>
 #include <asm/cp15.h>
@@ -30,6 +31,8 @@
 #define EXYNOS5420_USE_ARM_CORE_DOWN_STATE	BIT(29)
 #define EXYNOS5420_USE_L2_COMMON_UP_STATE	BIT(30)
 
+static void __iomem *ns_sram_base_addr;
+
 /*
  * The common v7_exit_coherency_flush API could not be used because of the
  * Erratum 799270 workaround. This macro is the same as the common one (in
@@ -318,10 +321,26 @@ static const struct of_device_id exynos_dt_mcpm_match[] = {
 	{},
 };
 
+static void exynos_mcpm_setup_entry_point(void)
+{
+	/*
+	 * U-Boot SPL is hardcoded to jump to the start of ns_sram_base_addr
+	 * as part of secondary_cpu_start().  Let's redirect it to the
+	 * mcpm_entry_point(). This is done during both secondary boot-up as
+	 * well as system resume.
+	 */
+	__raw_writel(0xe59f0000, ns_sram_base_addr);     /* ldr r0, [pc, #0] */
+	__raw_writel(0xe12fff10, ns_sram_base_addr + 4); /* bx  r0 */
+	__raw_writel(virt_to_phys(mcpm_entry_point), ns_sram_base_addr + 8);
+}
+
+static struct syscore_ops exynos_mcpm_syscore_ops = {
+	.resume	= exynos_mcpm_setup_entry_point,
+};
+
 static int __init exynos_mcpm_init(void)
 {
 	struct device_node *node;
-	void __iomem *ns_sram_base_addr;
 	unsigned int value, i;
 	int ret;
 
@@ -387,16 +406,9 @@ static int __init exynos_mcpm_init(void)
 		pmu_raw_writel(value, EXYNOS_COMMON_OPTION(i));
 	}
 
-	/*
-	 * U-Boot SPL is hardcoded to jump to the start of ns_sram_base_addr
-	 * as part of secondary_cpu_start().  Let's redirect it to the
-	 * mcpm_entry_point().
-	 */
-	__raw_writel(0xe59f0000, ns_sram_base_addr);     /* ldr r0, [pc, #0] */
-	__raw_writel(0xe12fff10, ns_sram_base_addr + 4); /* bx  r0 */
-	__raw_writel(virt_to_phys(mcpm_entry_point), ns_sram_base_addr + 8);
+	exynos_mcpm_setup_entry_point();
 
-	iounmap(ns_sram_base_addr);
+	register_syscore_ops(&exynos_mcpm_syscore_ops);
 
 	return ret;
 }
diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index adb36a8..7a1ebfe 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -126,6 +126,18 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  */
 void exynos_cpu_power_down(int cpu)
 {
+	if (cpu == 0 && (of_machine_is_compatible("samsung,exynos5420") ||
+		of_machine_is_compatible("samsung,exynos5800"))) {
+		/*
+		 * Bypass power down for CPU0 during suspend. Check for
+		 * the SYS_PWR_REG value to decide if we are suspending
+		 * the system.
+		 */
+		int val = pmu_raw_readl(EXYNOS5_ARM_CORE0_SYS_PWR_REG);
+
+		if (!(val & S5P_CORE_LOCAL_PWR_EN))
+			return;
+	}
 	pmu_raw_writel(0, EXYNOS_ARM_CORE_CONFIGURATION(cpu));
 }
 
diff --git a/arch/arm/mach-exynos/suspend.c b/arch/arm/mach-exynos/suspend.c
index 8cef614..cc8d237 100644
--- a/arch/arm/mach-exynos/suspend.c
+++ b/arch/arm/mach-exynos/suspend.c
@@ -24,6 +24,7 @@
 #include <asm/cacheflush.h>
 #include <asm/hardware/cache-l2x0.h>
 #include <asm/firmware.h>
+#include <asm/mcpm.h>
 #include <asm/smp_scu.h>
 #include <asm/suspend.h>
 
@@ -72,6 +73,7 @@ struct exynos_pm_data {
 	unsigned int *release_ret_regs;
 
 	void (*pm_prepare)(void);
+	void (*pm_resume_prepare)(void);
 	void (*pm_resume)(void);
 	int (*pm_suspend)(void);
 	int (*cpu_suspend)(unsigned long);
@@ -172,9 +174,28 @@ static int exynos_cpu_suspend(unsigned long arg)
 
 static int exynos5420_cpu_suspend(unsigned long arg)
 {
-	exynos_flush_cache_all();
+	/* MCPM works with HW CPU identifiers */
+	unsigned int mpidr = read_cpuid_mpidr();
+	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+
 	__raw_writel(0x0, sysram_base_addr + EXYNOS5420_CPU_STATE);
-	return exynos_cpu_do_idle();
+
+	if (IS_ENABLED(CONFIG_EXYNOS5420_MCPM)) {
+		mcpm_set_entry_vector(cpu, cluster, exynos_cpu_resume);
+
+		/*
+		 * Residency value passed to mcpm_cpu_suspend back-end
+		 * has to be given clear semantics. Set to 0 as a
+		 * temporary value.
+		 */
+		mcpm_cpu_suspend(0);
+	}
+
+	pr_info("Failed to suspend the system\n");
+
+	/* return value != 0 means failure */
+	return 1;
 }
 
 static void exynos_pm_set_wakeup_mask(void)
@@ -189,9 +210,6 @@ static void exynos_pm_enter_sleep_mode(void)
 	/* Set value of power down register for sleep mode */
 	exynos_sys_powerdown_conf(SYS_SLEEP);
 	pmu_raw_writel(S5P_CHECK_SLEEP, S5P_INFORM1);
-
-	/* ensure at least INFORM0 has the resume address */
-	pmu_raw_writel(virt_to_phys(exynos_cpu_resume), S5P_INFORM0);
 }
 
 static void exynos_pm_prepare(void)
@@ -206,6 +224,9 @@ static void exynos_pm_prepare(void)
 				pm_data->num_extra_save);
 
 	exynos_pm_enter_sleep_mode();
+
+	/* ensure at least INFORM0 has the resume address */
+	pmu_raw_writel(virt_to_phys(exynos_cpu_resume), S5P_INFORM0);
 }
 
 static void exynos5420_pm_prepare(void)
@@ -230,6 +251,10 @@ static void exynos5420_pm_prepare(void)
 
 	exynos_pm_enter_sleep_mode();
 
+	/* ensure at least INFORM0 has the resume address */
+	if (IS_ENABLED(CONFIG_EXYNOS5420_MCPM))
+		pmu_raw_writel(virt_to_phys(mcpm_entry_point), S5P_INFORM0);
+
 	tmp = pmu_raw_readl(EXYNOS5_ARM_L2_OPTION);
 	tmp &= ~EXYNOS5_USE_RETENTION;
 	pmu_raw_writel(tmp, EXYNOS5_ARM_L2_OPTION);
@@ -318,10 +343,21 @@ early_wakeup:
 	pmu_raw_writel(0x0, S5P_INFORM1);
 }
 
+static void exynos5420_prepare_pm_resume(void)
+{
+	if (IS_ENABLED(CONFIG_EXYNOS5420_MCPM))
+		WARN_ON(mcpm_cpu_powered_up());
+}
+
 static void exynos5420_pm_resume(void)
 {
 	unsigned long tmp;
 
+	/* Restore the CPU0 low power state register */
+	tmp = pmu_raw_readl(EXYNOS5_ARM_CORE0_SYS_PWR_REG);
+	pmu_raw_writel(tmp | S5P_CORE_LOCAL_PWR_EN,
+		EXYNOS5_ARM_CORE0_SYS_PWR_REG);
+
 	/* Restore the sysram cpu state register */
 	__raw_writel(exynos5420_cpu_state,
 		sysram_base_addr + EXYNOS5420_CPU_STATE);
@@ -391,6 +427,8 @@ static int exynos_suspend_enter(suspend_state_t state)
 	if (ret)
 		return ret;
 
+	if (pm_data->pm_resume_prepare)
+		pm_data->pm_resume_prepare();
 	s3c_pm_restore_uarts();
 
 	S3C_PMDBG("%s: wakeup stat: %08x\n", __func__,
@@ -448,6 +486,7 @@ static struct exynos_pm_data exynos5420_pm_data = {
 	.wkup_irq	= exynos5250_wkup_irq,
 	.wake_disable_mask = (0x7F << 7) | (0x1F << 1),
 	.release_ret_regs = exynos5420_release_ret_regs,
+	.pm_resume_prepare = exynos5420_prepare_pm_resume,
 	.pm_resume	= exynos5420_pm_resume,
 	.pm_suspend	= exynos5420_pm_suspend,
 	.pm_prepare	= exynos5420_pm_prepare,
-- 
1.7.9.5
