Exynos542x: Add workaround for exynos iROM errata

iROM logic provides undesired jump address for CPU2.
This patch adds a programmable susbstitute for a part of
iROM logic which wakes up cores and provides jump addresses.
This patch creates a logic to make all secondary cores jump
to a particular address which evades the possibility of CPU2
jumping to wrong address and create undesired results.

Logic of the workaround:

Step-1: iROM code checks value at address 0x2020028.
Step-2: If value is 0xc9cfcfcf, it jumps to the address (0x202000+CPUid*4),
	else, it continues executing normally.
Step-3: Primary core puts secondary cores in WFE and store 0xc9cfcfcf in
	0x2020028 and jump address (pointer to function low_power_start)
	in (0x202000+CPUid*4).
Step-4: When secondary cores recieve event signal they jump to this address
	and continue execution.

Signed-off-by: Kimoon Kim <kimoon.kim@samsung.com>
Signed-off-by: Akshay Saraswat <akshay.s@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

arch/arm/cpu/armv7/exynos/Makefile

@@ -7,6 +7,8 @@
 
 obj-y	+= clock.o power.o soc.o system.o pinmux.o tzpc.o
 
+obj-$(CONFIG_EXYNOS5420)	+= sec_boot.o
+
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_EXYNOS5)	+= clock_init_exynos5.o
 obj-$(CONFIG_EXYNOS5)	+= dmc_common.o dmc_init_ddr3.o

arch/arm/cpu/armv7/exynos/lowlevel_init.c

@@ -32,6 +32,7 @@
 #include <asm/arch/periph.h>
 #include <asm/arch/pinmux.h>
 #include <asm/arch/system.h>
+#include <asm/armv7.h>
 #include "common_setup.h"
 #include "exynos5_setup.h"
 
@@ -45,6 +46,61 @@ enum {
 };
 
 #ifdef CONFIG_EXYNOS5420
+/*
+ * Power up secondary CPUs.
+ */
+static void secondary_cpu_start(void)
+{
+	v7_enable_smp(EXYNOS5420_INFORM_BASE);
+	svc32_mode_en();
+	set_pc(CONFIG_EXYNOS_RELOCATE_CODE_BASE);
+}
+
+/*
+ * This is the entry point of hotplug-in and
+ * cluster switching.
+ */
+static void low_power_start(void)
+{
+	uint32_t val, reg_val;
+
+	reg_val = readl(EXYNOS5420_SPARE_BASE);
+	if (reg_val != CPU_RST_FLAG_VAL) {
+		writel(0x0, CONFIG_LOWPOWER_FLAG);
+		set_pc(0x0);
+	}
+
+	reg_val = readl(CONFIG_PHY_IRAM_BASE + 0x4);
+	if (reg_val != (uint32_t)&low_power_start) {
+		/* Store jump address as low_power_start if not present */
+		writel((uint32_t)&low_power_start, CONFIG_PHY_IRAM_BASE + 0x4);
+		dsb();
+		sev();
+	}
+
+	/* Set the CPU to SVC32 mode */
+	svc32_mode_en();
+	v7_enable_l2_hazard_detect();
+
+	/* Invalidate L1 & TLB */
+	val = 0x0;
+	mcr_tlb(val);
+	mcr_icache(val);
+
+	/* Disable MMU stuff and caches */
+	mrc_sctlr(val);
+
+	val &= ~((0x2 << 12) | 0x7);
+	val |= ((0x1 << 12) | (0x8 << 8) | 0x2);
+	mcr_sctlr(val);
+
+	/* CPU state is hotplug or reset */
+	secondary_cpu_start();
+
+	/* Core should not enter into WFI here */
+	wfi();
+}
+
 /*
  * Pointer to this function is stored in iRam which is used
  * for jump and power down of a specific core.
@@ -81,29 +137,25 @@ static void power_down_core(void)
  */
 static void secondary_cores_configure(void)
 {
-	uint32_t core_id;
+	/* Setup L2 cache */
+	v7_enable_l2_hazard_detect();
 
-	/* Store jump address for power down of secondary cores */
+	/* Clear secondary boot iRAM base */
+	writel(0x0, (CONFIG_EXYNOS_RELOCATE_CODE_BASE + 0x1C));
+
+	/* set lowpower flag and address */
+	writel(CPU_RST_FLAG_VAL, CONFIG_LOWPOWER_FLAG);
+	writel((uint32_t)&low_power_start, CONFIG_LOWPOWER_ADDR);
+	writel(CPU_RST_FLAG_VAL, EXYNOS5420_SPARE_BASE);
+	/* Store jump address for power down */
 	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();
-	}
 }
+
+extern void relocate_wait_code(void);
 #endif
 
 int do_lowlevel_init(void)
@@ -114,6 +166,8 @@ int do_lowlevel_init(void)
 	arch_cpu_init();
 
 #ifdef CONFIG_EXYNOS5420
+	relocate_wait_code();
+
 	/* Reconfigure secondary cores */
 	secondary_cores_configure();
 #endif

arch/arm/cpu/armv7/exynos/sec_boot.S

+/*
+ * Copyright (C) 2013 Samsung Electronics
+ * Akshay Saraswat <akshay.s@samsung.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <asm/arch/cpu.h>
+
+	.globl relocate_wait_code
+relocate_wait_code:
+	adr     r0, code_base		@ r0: source address (start)
+	adr     r1, code_end		@ r1: source address (end)
+	ldr     r2, =0x02073000		@ r2: target address
+1:
+	ldmia   r0!, {r3-r6}
+	stmia   r2!, {r3-r6}
+	cmp     r0, r1
+	blt     1b
+	b	code_end
+	.ltorg
+/*
+ * Secondary core waits here until Primary wake it up.
+ * Below code is copied to CONFIG_EXYNOS_RELOCATE_CODE_BASE.
+ * This is a workaround code which is supposed to act as a
+ * substitute/supplement to the iROM code.
+ *
+ * This workaround code is relocated to the address 0x02073000
+ * because that comes out to be the last 4KB of the iRAM
+ * (Base Address - 0x02020000, Limit Address - 0x020740000).
+ *
+ * U-boot and kernel are aware of this code and flags by the simple
+ * fact that we are implementing a workaround in the last 4KB
+ * of the iRAM and we have already defined these flag and address
+ * values in both kernel and U-boot for our use.
+ */
+code_base:
+	b	 1f
+/*
+ * These addresses are being used as flags in u-boot and kernel.
+ *
+ * Jump address for resume and flag to check for resume/reset:
+ * Resume address - 0x2073008
+ * Resume flag - 0x207300C
+ *
+ * Jump address for cluster switching:
+ * Switch address - 0x2073018
+ *
+ * Jump address for core hotplug:
+ * Hotplug address - 0x207301C
+ *
+ * Jump address for C2 state (Reserved for future not being used right now):
+ * C2 address - 0x2073024
+ *
+ * Managed per core status for the active cluster:
+ * CPU0 state - 0x2073028
+ * CPU1 state - 0x207302C
+ * CPU2 state - 0x2073030
+ * CPU3 state - 0x2073034
+ *
+ * Managed per core GIC status for the active cluster:
+ * CPU0 gic state - 0x2073038
+ * CPU1 gic state - 0x207303C
+ * CPU2 gic state - 0x2073040
+ * CPU3 gic state - 0x2073044
+ *
+ * Logic of the code:
+ * Step-1: Read current CPU status.
+ * Step-2: If it's a resume then continue, else jump to step 4.
+ * Step-3: Clear inform1 PMU register and jump to inform0 value.
+ * Step-4: If it's a switch, C2 or reset, get the hotplug address.
+ * Step-5: If address is not available, enter WFE.
+ * Step-6: If address is available, jump to that address.
+ */
+	nop			     @ for backward compatibility
+	.word   0x0		     @ REG0: RESUME_ADDR
+	.word   0x0		     @ REG1: RESUME_FLAG
+	.word   0x0		     @ REG2
+	.word   0x0		     @ REG3
+_switch_addr:
+	.word   0x0		     @ REG4: SWITCH_ADDR
+_hotplug_addr:
+	.word   0x0		     @ REG5: CPU1_BOOT_REG
+	.word   0x0		     @ REG6
+_c2_addr:
+	.word   0x0		     @ REG7: REG_C2_ADDR
+_cpu_state:
+	.word   0x1		     @ CPU0_STATE : RESET
+	.word   0x2		     @ CPU1_STATE : SECONDARY RESET
+	.word   0x2		     @ CPU2_STATE : SECONDARY RESET
+	.word   0x2		     @ CPU3_STATE : SECONDARY RESET
+_gic_state:
+	.word   0x0		     @ CPU0 - GICD_IGROUPR0
+	.word   0x0		     @ CPU1 - GICD_IGROUPR0
+	.word   0x0		     @ CPU2 - GICD_IGROUPR0
+	.word   0x0		     @ CPU3 - GICD_IGROUPR0
+1:
+	adr     r0, _cpu_state
+	mrc     p15, 0, r7, c0, c0, 5   @ read MPIDR
+	and     r7, r7, #0xf	    @ r7 = cpu id
+/* Read the current cpu state */
+	ldr     r10, [r0, r7, lsl #2]
+svc_entry:
+	tst     r10, #(1 << 4)
+	adrne   r0, _switch_addr
+	bne     wait_for_addr
+/* Clear INFORM1 */
+	ldr     r0, =(0x10040000 + 0x804)
+	ldr     r1, [r0]
+	cmp     r1, #0x0
+	movne   r1, #0x0
+	strne   r1, [r0]
+/* Get INFORM0 */
+	ldrne   r1, =(0x10040000 + 0x800)
+	ldrne   pc, [r1]
+	tst     r10, #(1 << 0)
+	ldrne   pc, =0x23e00000
+	adr     r0, _hotplug_addr
+wait_for_addr:
+	ldr     r1, [r0]
+	cmp     r1, #0x0
+	bxne    r1
+	wfe
+	b	 wait_for_addr
+	.ltorg
+code_end:
+	mov	pc, lr