ARM: exynos: Fix imprecise abort during Exynos5422 suspend to RAM

Suspend to RAM on Odroid XU3/XU4/HC1 family (Exynos5422) causes
imprecise abort:

PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.003 seconds) done.
OOM killer disabled.
Freezing remaining freezable tasks ... (elapsed 0.003 seconds) done.
wake enabled for irq 139
Disabling non-boot CPUs ...
IRQ51 no longer affine to CPU1
IRQ52 no longer affine to CPU2
IRQ53 no longer affine to CPU3
IRQ54 no longer affine to CPU4
IRQ55 no longer affine to CPU5
IRQ56 no longer affine to CPU6
cpu cpu4: Dropping the link to regulator.40
IRQ57 no longer affine to CPU7
Unhandled fault: external abort on non-linefetch (0x1008) at 0xf081a028
Internal error: : 1008 [#1] PREEMPT SMP ARM

with last call trace in exynos_suspend_enter().

The abort is caused by writing to register in secure part of sysram.
Boards booted under secure firmware (e.g. Hardkernel Odroid boards)
should access non-secure sysram.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>

Documentation/arm/Samsung/Bootloader-interface.txt

···
 0x20          0xfcba0d10 (Magic cookie)                    AFTR
 0x24          exynos_cpu_resume_ns                         AFTR
 0x28 + 4*cpu  0x8 (Magic cookie, Exynos3250)               AFTR
+0x28          0x0 or last value during resume (Exynos542x) System suspend
 
 
 2. Secure mode

arch/arm/mach-exynos/common.h

···
 #define EXYNOS_SLEEP_MAGIC	0x00000bad
 #define EXYNOS_AFTR_MAGIC	0xfcba0d10
 
+bool __init exynos_secure_firmware_available(void);
 void exynos_set_boot_flag(unsigned int cpu, unsigned int mode);
 void exynos_clear_boot_flag(unsigned int cpu, unsigned int mode);
 

arch/arm/mach-exynos/firmware.c

···
 	exynos_smc(SMC_CMD_L2X0SETUP2, regs->pwr_ctrl, regs->aux_ctrl, 0);
 }
 
-void __init exynos_firmware_init(void)
+bool __init exynos_secure_firmware_available(void)
 {
 	struct device_node *nd;
 	const __be32 *addr;
···
 	nd = of_find_compatible_node(NULL, NULL,
 					"samsung,secure-firmware");
 	if (!nd)
-		return;
+		return false;
 
 	addr = of_get_address(nd, 0, NULL, NULL);
 	if (!addr) {
 		pr_err("%s: No address specified.\n", __func__);
-		return;
+		return false;
 	}
+
+	return true;
+}
+
+void __init exynos_firmware_init(void)
+{
+	if (!exynos_secure_firmware_available())
+		return;
 
 	pr_info("Running under secure firmware.\n");
 

arch/arm/mach-exynos/suspend.c

···
 struct exynos_pm_state {
 	int cpu_state;
 	unsigned int pmu_spare3;
+	void __iomem *sysram_base;
 };
 
 static const struct exynos_pm_data *pm_data __ro_after_init;
···
 	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
 	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
 
-	writel_relaxed(0x0, sysram_base_addr + EXYNOS5420_CPU_STATE);
+	writel_relaxed(0x0, pm_state.sysram_base + EXYNOS5420_CPU_STATE);
 
 	if (IS_ENABLED(CONFIG_EXYNOS5420_MCPM)) {
 		mcpm_set_entry_vector(cpu, cluster, exynos_cpu_resume);
···
 	 * needs to restore it back in case, the primary cpu fails to
 	 * suspend for any reason.
 	 */
-	pm_state.cpu_state = readl_relaxed(sysram_base_addr +
+	pm_state.cpu_state = readl_relaxed(pm_state.sysram_base +
 					   EXYNOS5420_CPU_STATE);
 
 	exynos_pm_enter_sleep_mode();
···
 
 	/* Restore the sysram cpu state register */
 	writel_relaxed(pm_state.cpu_state,
-		       sysram_base_addr + EXYNOS5420_CPU_STATE);
+		       pm_state.sysram_base + EXYNOS5420_CPU_STATE);
 
 	pmu_raw_writel(EXYNOS5420_USE_STANDBY_WFI_ALL,
 			S5P_CENTRAL_SEQ_OPTION);
···
 
 	register_syscore_ops(&exynos_pm_syscore_ops);
 	suspend_set_ops(&exynos_suspend_ops);
+
+	/*
+	 * Applicable as of now only to Exynos542x. If booted under secure
+	 * firmware, the non-secure region of sysram should be used.
+	 */
+	if (exynos_secure_firmware_available())
+		pm_state.sysram_base = sysram_ns_base_addr;
+	else
+		pm_state.sysram_base = sysram_base_addr;
 }