[U-Boot] [PATCH v2 02/11] Exynos542x: CPU: Power down all secondary cores

[Akshay Saraswat <akshay.s@samsung.com>]

This patch adds code to shutdown secondary cores.
When U-boot comes up, all secondary cores appear powered on,
which is undesirable and causes side effects while
initializing these cores in kernel.

Secondary core power down happens in following steps:

Step-1: After Exynos power-on, primary core starts executing first.
Step-2: In iROM code every core has to check 2 flags i.e.
	addresses 0x02020028 & 0x02020004.
Step-3: Initially 0x02020028 is 0 for all cores and 0x02020004 has a
	jump address for primary core and 0 for all secondary cores.
Step-4: Therefore, primary core follows normal iROM execution and jumps
	to BL1 eventually, whereas all secondary cores enter WFE.
Step-5: When primary core comes into function secondary_cores_configure,
	it puts pointer to function power_down_core into 0x02020004
	and provides DSB and SEV for all cores so that they may come out
	of WFE and jump to power_down_core function.
Step-6: And ultimately because of power_down_core all
	secondary cores shut-down.

Signed-off-by: Kimoon Kim <kimoon.kim@samsung.com>
Signed-off-by: Akshay Saraswat <akshay.s@samsung.com>
---
Changes since v1:
	- Removed unnecessary macros.
	- Changed names of few macros for better understanding.
	- Added MPIDR bit assignment info comment in power_down_core.

 arch/arm/cpu/armv7/exynos/exynos5_setup.h |  3 ++
 arch/arm/cpu/armv7/exynos/lowlevel_init.c | 69 ++++++++++++++++++++++++
 arch/arm/include/asm/arch-exynos/cpu.h    |  5 ++
 arch/arm/include/asm/arch-exynos/system.h | 87 +++++++++++++++++++++++++++++++
 4 files changed, 164 insertions(+)

diff --git a/arch/arm/cpu/armv7/exynos/exynos5_setup.h b/arch/arm/cpu/armv7/exynos/exynos5_setup.h
index 2eea48a..9073f50 100644
--- a/arch/arm/cpu/armv7/exynos/exynos5_setup.h
+++ b/arch/arm/cpu/armv7/exynos/exynos5_setup.h
@@ -700,6 +700,9 @@
 #define CLK_DIV_CPERI1_VAL	NOT_AVAILABLE
 
 #else
+
+#define CPU_CONFIG_STATUS_OFFSET	0x80
+#define CPU_RST_FLAG_VAL		0xFCBA0D10
 #define PAD_RETENTION_DRAM_COREBLK_VAL	0x10000000
 
 /* APLL_CON1 */
diff --git a/arch/arm/cpu/armv7/exynos/lowlevel_init.c b/arch/arm/cpu/armv7/exynos/lowlevel_init.c
index 83e1dcf..e36f2fa 100644
--- a/arch/arm/cpu/armv7/exynos/lowlevel_init.c
+++ b/arch/arm/cpu/armv7/exynos/lowlevel_init.c
@@ -31,7 +31,9 @@
 #include <asm/arch/tzpc.h>
 #include <asm/arch/periph.h>
 #include <asm/arch/pinmux.h>
+#include <asm/arch/system.h>
 #include "common_setup.h"
+#include "exynos5_setup.h"
 
 /* These are the things we can do during low-level init */
 enum {
@@ -42,6 +44,68 @@ enum {
 	DO_POWER	= 1 << 4,
 };
 
+#ifdef CONFIG_EXYNOS5420
+/*
+ * Pointer to this function is stored in iRam which is used
+ * for jump and power down of a specific core.
+ */
+static void power_down_core(void)
+{
+	uint32_t tmp, core_id, core_config;
+
+	/* Get the unique core id */
+	/*
+	 * Multiprocessor Affinity Register
+	 * [11:8]	Cluster ID
+	 * [1:0]	CPU ID
+	 */
+	mrc_mpafr(core_id);
+	tmp = core_id & 0x3;
+	core_id = (core_id >> 6) & ~3;
+	core_id |= tmp;
+	core_id &= 0x3f;
+
+	/* Set the status of the core to low */
+	core_config = (core_id * CPU_CONFIG_STATUS_OFFSET);
+	core_config += EXYNOS5420_CPU_CONFIG_BASE;
+	writel(0x0, core_config);
+
+	/* Core enter WFI */
+	wfi();
+}
+
+/*
+ * Configurations for secondary cores are inapt at this stage.
+ * Reconfigure secondary cores. Shutdown and change the status
+ * of all cores except the primary core.
+ */
+static void secondary_cores_configure(void)
+{
+	uint32_t core_id;
+
+	/* Store jump address for power down of secondary cores */
+	writel((uint32_t)&power_down_core, CONFIG_PHY_IRAM_BASE + 0x4);
+
+	/* Need all core power down check */
+	dsb();
+	sev();
+
+	/*
+	 * Power down all cores(secondary) while primary core must
+	 * wait for all cores to go down.
+	 */
+	for (core_id = 1; core_id != CONFIG_CORE_COUNT; core_id++) {
+		while ((readl(EXYNOS5420_CPU_STATUS_BASE
+			+ (core_id * CPU_CONFIG_STATUS_OFFSET))
+			& 0xff) != 0x0) {
+			isb();
+			sev();
+		}
+		isb();
+	}
+}
+#endif
+
 int do_lowlevel_init(void)
 {
 	uint32_t reset_status;
@@ -49,6 +113,11 @@ int do_lowlevel_init(void)
 
 	arch_cpu_init();
 
+#ifdef CONFIG_EXYNOS5420
+	/* Reconfigure secondary cores */
+	secondary_cores_configure();
+#endif
+
 	reset_status = get_reset_status();
 
 	switch (reset_status) {
diff --git a/arch/arm/include/asm/arch-exynos/cpu.h b/arch/arm/include/asm/arch-exynos/cpu.h
index 29674ad..e739520 100644
--- a/arch/arm/include/asm/arch-exynos/cpu.h
+++ b/arch/arm/include/asm/arch-exynos/cpu.h
@@ -153,6 +153,10 @@
 #define EXYNOS5420_CLOCK_BASE		0x10010000
 #define EXYNOS5420_POWER_BASE		0x10040000
 #define EXYNOS5420_SWRESET		0x10040400
+#define EXYNOS5420_INFORM_BASE		0x10040800
+#define EXYNOS5420_SPARE_BASE		0x10040900
+#define EXYNOS5420_CPU_CONFIG_BASE	0x10042000
+#define EXYNOS5420_CPU_STATUS_BASE	0x10042004
 #define EXYNOS5420_SYSREG_BASE		0x10050000
 #define EXYNOS5420_TZPC_BASE		0x100E0000
 #define EXYNOS5420_WATCHDOG_BASE	0x101D0000
@@ -186,6 +190,7 @@
 #define EXYNOS5420_USB3PHY_BASE		DEVICE_NOT_AVAILABLE
 #define EXYNOS5420_USB_HOST_XHCI_BASE	DEVICE_NOT_AVAILABLE
 
+
 #ifndef __ASSEMBLY__
 #include <asm/io.h>
 /* CPU detection macros */
diff --git a/arch/arm/include/asm/arch-exynos/system.h b/arch/arm/include/asm/arch-exynos/system.h
index 4968d3d..86903c3 100644
--- a/arch/arm/include/asm/arch-exynos/system.h
+++ b/arch/arm/include/asm/arch-exynos/system.h
@@ -37,6 +37,93 @@ struct exynos5_sysreg {
 
 #define USB20_PHY_CFG_HOST_LINK_EN	(1 << 0)
 
+#ifdef CONFIG_EXYNOS5420
+/*
+ * Data Synchronization Barrier acts as a special kind of memory barrier.
+ * No instruction in program order after this instruction executes until
+ * this instruction completes. This instruction completes when:
+ * - All explicit memory accesses before this instruction complete.
+ * - All Cache, Branch predictor and TLB maintenance operations before
+ *   this instruction complete.
+ */
+#define dsb() __asm__ __volatile__ ("dsb\n\t" : : );
+
+/*
+ * This instruction causes an event to be signaled to all cores
+ * within a multiprocessor system. If SEV is implemented,
+ * WFE must also be implemented.
+ */
+#define sev() __asm__ __volatile__ ("sev\n\t" : : );
+/*
+ * If the Event Register is not set, WFE suspends execution until
+ * one of the following events occurs:
+ * - an IRQ interrupt, unless masked by the CPSR I-bit
+ * - an FIQ interrupt, unless masked by the CPSR F-bit
+ * - an Imprecise Data abort, unless masked by the CPSR A-bit
+ * - a Debug Entry request, if Debug is enabled
+ * - an Event signaled by another processor using the SEV instruction.
+ * If the Event Register is set, WFE clears it and returns immediately.
+ * If WFE is implemented, SEV must also be implemented.
+ */
+#define wfe() __asm__ __volatile__ ("wfe\n\t" : : );
+
+/* Move 0xd3 value to CPSR register to enable SVC mode */
+#define svc32_mode_en() __asm__ __volatile__				\
+			("@ I&F disable, Mode: 0x13 - SVC\n\t"		\
+			 "msr     cpsr_c, #0x13|0xC0\n\t" : : )
+
+/* Set program counter with the given value */
+#define set_pc(x) __asm__ __volatile__ ("mov     pc, %0\n\t" : : "r"(x))
+
+/* Read Main Id register */
+#define mrc_midr(x) __asm__ __volatile__	\
+			("mrc     p15, 0, %0, c0, c0, 0\n\t" : "=r"(x) : )
+
+/* Read Multiprocessor Affinity Register */
+#define mrc_mpafr(x) __asm__ __volatile__	\
+			("mrc     p15, 0, %0, c0, c0, 5\n\t" : "=r"(x) : )
+
+/* Read System Control Register */
+#define mrc_sctlr(x) __asm__ __volatile__	\
+			("mrc     p15, 0, %0, c1, c0, 0\n\t" : "=r"(x) : )
+
+/* Read Auxiliary Control Register */
+#define mrc_auxr(x) __asm__ __volatile__	\
+			("mrc     p15, 0, %0, c1, c0, 1\n\t" : "=r"(x) : )
+
+/* Read L2 Control register */
+#define mrc_l2_ctlr(x) __asm__ __volatile__	\
+			("mrc     p15, 1, %0, c9, c0, 2\n\t" : "=r"(x) : )
+
+/* Read L2 Auxilliary Control register */
+#define mrc_l2_aux_ctlr(x) __asm__ __volatile__	\
+			("mrc     p15, 1, %0, c15, c0, 0\n\t" : "=r"(x) : )
+
+/* Write System Control Register */
+#define mcr_sctlr(x) __asm__ __volatile__	\
+			("mcr     p15, 0, %0, c1, c0, 0\n\t" : : "r"(x))
+
+/* Write Auxiliary Control Register */
+#define mcr_auxr(x) __asm__ __volatile__	\
+			("mcr     p15, 0, %0, c1, c0, 1\n\t" : : "r"(x))
+
+/* Invalidate all instruction caches to PoU */
+#define mcr_icache(x) __asm__ __volatile__	\
+			("mcr     p15, 0, %0, c7, c5, 0\n\t" : : "r"(x))
+
+/* Invalidate unified TLB */
+#define mcr_tlb(x) __asm__ __volatile__	\
+			("mcr     p15, 0, %0, c8, c7, 0\n\t" : : "r"(x))
+
+/* Write L2 Control register */
+#define mcr_l2_ctlr(x) __asm__ __volatile__	\
+			("mcr     p15, 1, %0, c9, c0, 2\n\t" : : "r"(x))
+
+/* Write L2 Auxilliary Control register */
+#define mcr_l2_aux_ctlr(x) __asm__ __volatile__	\
+			("mcr     p15, 1, %0, c15, c0, 0\n\t" : : "r"(x))
+#endif
+
 void set_usbhost_mode(unsigned int mode);
 void set_system_display_ctrl(void);
 int exynos_lcd_early_init(const void *blob);
-- 
1.9.1