ARM: imx: Deduplicate i.MX8M SNVS LPGPR unlock

Pull this LPGPR unlock into common code, since it is used in multiple
systems already.

Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/arch/arm/include/asm/arch-imx8m/imx-regs.h b/arch/arm/include/asm/arch-imx8m/imx-regs.h
index ff3b9dd..29d5baa 100644
--- a/arch/arm/include/asm/arch-imx8m/imx-regs.h
+++ b/arch/arm/include/asm/arch-imx8m/imx-regs.h
@@ -27,6 +27,7 @@
 #define IOMUXC_GPR_BASE_ADDR	0x30340000
 #define OCOTP_BASE_ADDR		0x30350000
 #define ANATOP_BASE_ADDR	0x30360000
+#define SNVS_BASE_ADDR		0x30370000
 #define CCM_BASE_ADDR		0x30380000
 #define SRC_BASE_ADDR		0x30390000
 #define GPC_BASE_ADDR		0x303A0000
@@ -113,6 +114,10 @@
 #define SRC_DDR1_RCR_CORE_RESET_N_MASK	BIT(1)
 #define SRC_DDR1_RCR_PRESET_N_MASK	BIT(0)
 
+#define SNVS_LPSR			0x4c
+#define SNVS_LPLVDR			0x64
+#define SNVS_LPPGDR_INIT		0x41736166
+
 struct iomuxc_gpr_base_regs {
 	u32 gpr[47];
 };
diff --git a/arch/arm/mach-imx/imx8m/soc.c b/arch/arm/mach-imx/imx8m/soc.c
index d115b25..5739546 100644
--- a/arch/arm/mach-imx/imx8m/soc.c
+++ b/arch/arm/mach-imx/imx8m/soc.c
@@ -544,6 +544,16 @@
 }
 EVENT_SPY(EVT_DM_POST_INIT, imx8m_check_clock);
 
+static void imx8m_setup_snvs(void)
+{
+	/* Enable SNVS clock */
+	clock_enable(CCGR_SNVS, 1);
+	/* Initialize glitch detect */
+	writel(SNVS_LPPGDR_INIT, SNVS_BASE_ADDR + SNVS_LPLVDR);
+	/* Clear interrupt status */
+	writel(0xffffffff, SNVS_BASE_ADDR + SNVS_LPSR);
+}
+
 int arch_cpu_init(void)
 {
 	struct ocotp_regs *ocotp = (struct ocotp_regs *)OCOTP_BASE_ADDR;
@@ -594,6 +604,8 @@
 			writel(0x200, &ocotp->ctrl_clr);
 	}
 
+	imx8m_setup_snvs();
+
 	return 0;
 }