[PATCH v3] ARM: EXYNOS: SWRESET is needed to boot secondary CPU on Exynos3250

[Krzysztof Kozlowski]

Without software reset the secondary CPU does not power up and
exynos_boot_secondary() ends with pen_release equal to 1. This can be
observed in dmesg:
	CPU1: failed to come online
	Brought up 1 CPUs
	SMP: Total of 1 processors activated.
	CPU: All CPU(s) started in SVC mode.

When booting the secondary CPU on Exynos3250 execute also software
reset for core 1.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski at samsung.com>
Reviewed-by: Tomasz Figa <t.figa at samsung.com>

---

Changes since v2:
1. Rebase on Kukjin's for-next tree from 24th of September
(v3.17-rc3-97-gbcf20e084a4b)

Changes since v1:
1. Removed inline keyword and change if statement to early return as
   Tomasz suggested.
2. Added reviewed-by Tomasz Figa.
---
 arch/arm/mach-exynos/platsmp.c  | 23 +++++++++++++++++++++++
 arch/arm/mach-exynos/regs-pmu.h |  2 ++
 2 files changed, 25 insertions(+)

diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index 41ae28d69e6f..8543064dc445 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -121,6 +121,26 @@ static inline void __iomem *cpu_boot_reg(int cpu)
 }
 
 /*
+ * Set wake up by local power mode and execute software reset for given core.
+ *
+ * Currently this is needed only when booting secondary CPU on Exynos3250.
+ */
+static void exynos_core_restart(u32 core_id)
+{
+	u32 val;
+
+	if (!of_machine_is_compatible("samsung,exynos3250"))
+		return;
+
+	val = pmu_raw_readl(EXYNOS_ARM_CORE_STATUS(core_id));
+	val |= S5P_CORE_WAKEUP_FROM_LOCAL_CFG;
+	pmu_raw_writel(val, EXYNOS_ARM_CORE_STATUS(core_id));
+
+	pr_info("CPU%u: Software reset\n", core_id);
+	pmu_raw_writel(EXYNOS_CORE_PO_RESET(core_id), EXYNOS_SWRESET);
+}
+
+/*
  * Write pen_release in a way that is guaranteed to be visible to all
  * observers, irrespective of whether they're taking part in coherency
  * or not.  This is necessary for the hotplug code to work reliably.
@@ -196,6 +216,9 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
 			return -ETIMEDOUT;
 		}
 	}
+
+	exynos_core_restart(core_id);
+
 	/*
 	 * Send the secondary CPU a soft interrupt, thereby causing
 	 * the boot monitor to read the system wide flags register,
diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
index 30c03017aa6a..4ea5e320c6d1 100644
--- a/arch/arm/mach-exynos/regs-pmu.h
+++ b/arch/arm/mach-exynos/regs-pmu.h
@@ -21,6 +21,7 @@
 #define S5P_USE_STANDBY_WFI0			(1 << 16)
 #define S5P_USE_STANDBY_WFE0			(1 << 24)
 
+#define EXYNOS_CORE_PO_RESET(n)			((1 << 4) << n)
 #define EXYNOS_WAKEUP_FROM_LOWPWR		(1 << 28)
 #define EXYNOS_SWRESET				0x0400
 #define EXYNOS5440_SWRESET			0x00C4
@@ -125,6 +126,7 @@
 #define S5P_PAD_RET_EBIB_OPTION			0x31A8
 
 #define S5P_CORE_LOCAL_PWR_EN			0x3
+#define S5P_CORE_WAKEUP_FROM_LOCAL_CFG		(0x3 << 8)
 
 /* Only for EXYNOS4210 */
 #define S5P_CMU_CLKSTOP_LCD1_LOWPWR	0x1154
-- 
1.9.1