MLK-12495 mx6: Add LDO bypass support

Port LDO bypass support from v2015 to support the features:

1. Add check for 1.2GHz core speed. If Speed grading fuse is for 1.2GHz,
   enable LDO bypass and setup PMIC voltages. LDO bypass is dependent
   on the flatten device tree file.

2. We set WDOG_B in set_anatop_bypass() before, because it is the only case, but now
   on i.mx6sabreauto board, we didn't use ldo-bypass mode, but have to use WDOG_B to
   reboot whole board, so split these code to independent function so that board file
   can call it freely.

Signed-off-by: Ye Li <ye.li@nxp.com>

3 files changed, 156 insertions, 2 deletions

diff --git a/arch/arm/cpu/armv7/mx6/soc.c b/arch/arm/cpu/armv7/mx6/soc.c
index 77417b2..c1209b5 100644
--- a/arch/arm/cpu/armv7/mx6/soc.c
+++ b/arch/arm/cpu/armv7/mx6/soc.c
@@ -478,7 +478,7 @@ void imx_get_mac_from_fuse(int dev_id, unsigned char *mac)
 	struct fuse_bank4_regs *fuse =
 			(struct fuse_bank4_regs *)bank->fuse_regs;
 
-	if ((is_cpu_type(MXC_CPU_MX6SX) || is_cpu_type(MXC_CPU_MX6UL)) && 
+	if ((is_cpu_type(MXC_CPU_MX6SX) || is_cpu_type(MXC_CPU_MX6UL)) &&
 		dev_id == 1) {
 		u32 value = readl(&fuse->mac_addr2);
 		mac[0] = value >> 24 ;
@@ -489,7 +489,7 @@ void imx_get_mac_from_fuse(int dev_id, unsigned char *mac)
 		value = readl(&fuse->mac_addr1);
 		mac[4] = value >> 24 ;
 		mac[5] = value >> 16 ;
-		
+
 	} else {
 		u32 value = readl(&fuse->mac_addr1);
 		mac[0] = (value >> 8);
@@ -528,6 +528,28 @@ const struct boot_mode soc_boot_modes[] = {
 	{NULL,		0},
 };
 
+void set_wdog_reset(struct wdog_regs *wdog)
+{
+	u32 reg = readw(&wdog->wcr);
+	/*
+	 * use WDOG_B mode to reset external pmic because it's risky for the
+	 * following watchdog reboot in case of cpu freq at lowest 400Mhz with
+	 * ldo-bypass mode. Because boot frequency maybe higher 800Mhz i.e. So
+	 * in ldo-bypass mode watchdog reset will only triger POR reset, not
+	 * WDOG reset. But below code depends on hardware design, if HW didn't
+	 * connect WDOG_B pin to external pmic such as i.mx6slevk, we can skip
+	 * these code since it assumed boot from 400Mhz always.
+	 */
+	reg = readw(&wdog->wcr);
+	reg |= 1 << 3;
+	/*
+	 * WDZST bit is write-once only bit. Align this bit in kernel,
+	 * otherwise kernel code will have no chance to set this bit.
+	 */
+	reg |= 1 << 0;
+	writew(reg, &wdog->wcr);
+}
+
 void reset_misc(void)
 {
 #ifdef CONFIG_VIDEO_MXS
@@ -667,3 +689,122 @@ int arch_auxiliary_core_check_up(u32 core_id)
 	return 1;
 }
 #endif
+
+#ifdef CONFIG_LDO_BYPASS_CHECK
+DECLARE_GLOBAL_DATA_PTR;
+static int ldo_bypass;
+
+int check_ldo_bypass(void)
+{
+	const int *ldo_mode;
+	int node;
+
+	/* get the right fdt_blob from the global working_fdt */
+	gd->fdt_blob = working_fdt;
+	/* Get the node from FDT for anatop ldo-bypass */
+	node = fdt_node_offset_by_compatible(gd->fdt_blob, -1,
+		"fsl,imx6q-gpc");
+	if (node < 0) {
+		printf("No gpc device node %d, force to ldo-enable.\n", node);
+		return 0;
+	}
+	ldo_mode = fdt_getprop(gd->fdt_blob, node, "fsl,ldo-bypass", NULL);
+	/*
+	 * return 1 if "fsl,ldo-bypass = <1>", else return 0 if
+	 * "fsl,ldo-bypass = <0>" or no "fsl,ldo-bypass" property
+	 */
+	ldo_bypass = fdt32_to_cpu(*ldo_mode) == 1 ? 1 : 0;
+
+	return ldo_bypass;
+}
+
+int check_1_2G(void)
+{
+	u32 reg;
+	int result = 0;
+	struct ocotp_regs *ocotp = (struct ocotp_regs *)OCOTP_BASE_ADDR;
+	struct fuse_bank *bank = &ocotp->bank[0];
+	struct fuse_bank0_regs *fuse_bank0 =
+			(struct fuse_bank0_regs *)bank->fuse_regs;
+
+	reg = readl(&fuse_bank0->cfg3);
+	if (((reg >> 16) & 0x3) == 0x3) {
+		if (ldo_bypass) {
+			printf("Wrong dtb file used! i.MX6Q@1.2Ghz only "
+				"works with ldo-enable mode!\n");
+			/*
+			 * Currently, only imx6q-sabresd board might be here,
+			 * since only i.MX6Q support 1.2G and only Sabresd board
+			 * support ldo-bypass mode. So hardcode here.
+			 * You can also modify your board(i.MX6Q) dtb name if it
+			 * supports both ldo-bypass and ldo-enable mode.
+			 */
+			printf("Please use imx6q-sabresd-ldo.dtb!\n");
+			hang();
+		}
+		result = 1;
+	}
+
+	return result;
+}
+
+static int arm_orig_podf;
+void set_arm_freq_400M(bool is_400M)
+{
+	struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;
+
+	if (is_400M)
+		writel(0x1, &mxc_ccm->cacrr);
+	else
+		writel(arm_orig_podf, &mxc_ccm->cacrr);
+}
+
+void prep_anatop_bypass(void)
+{
+	struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;
+
+	arm_orig_podf = readl(&mxc_ccm->cacrr);
+	/*
+	 * Downgrade ARM speed to 400Mhz as half of boot 800Mhz before ldo
+	 * bypassed, also downgrade internal vddarm ldo to 0.975V.
+	 * VDDARM_IN 0.975V + 125mV = 1.1V < Max(1.3V)
+	 * otherwise at 800Mhz(i.mx6dl):
+	 * VDDARM_IN 1.175V + 125mV = 1.3V = Max(1.3V)
+	 * We need provide enough gap in this case.
+	 * skip if boot from 400M.
+	 */
+	if (!arm_orig_podf)
+		set_arm_freq_400M(true);
+
+	if (!is_cpu_type(MXC_CPU_MX6DL) && !is_cpu_type(MXC_CPU_MX6SX))
+		set_ldo_voltage(LDO_ARM, 975);
+	else
+		set_ldo_voltage(LDO_ARM, 1150);
+}
+
+int set_anatop_bypass(int wdog_reset_pin)
+{
+	struct anatop_regs *anatop = (struct anatop_regs *)ANATOP_BASE_ADDR;
+	struct wdog_regs *wdog;
+	u32 reg = readl(&anatop->reg_core);
+
+	/* bypass VDDARM/VDDSOC */
+	reg = reg | (0x1F << 18) | 0x1F;
+	writel(reg, &anatop->reg_core);
+
+	if (wdog_reset_pin == 2)
+		wdog = (struct wdog_regs *) WDOG2_BASE_ADDR;
+	else if (wdog_reset_pin == 1)
+		wdog = (struct wdog_regs *) WDOG1_BASE_ADDR;
+	else
+		return arm_orig_podf;
+	set_wdog_reset(wdog);
+	return arm_orig_podf;
+}
+
+void finish_anatop_bypass(void)
+{
+	if (!arm_orig_podf)
+		set_arm_freq_400M(false);
+}
+#endif
diff --git a/arch/arm/imx-common/cpu.c b/arch/arm/imx-common/cpu.c
index 3c7e7d1..cf84856 100644
--- a/arch/arm/imx-common/cpu.c
+++ b/arch/arm/imx-common/cpu.c
@@ -279,6 +279,9 @@ void arch_preboot_os(void)
 	disable_sata_clock();
 #endif
 #endif
+#if defined(CONFIG_LDO_BYPASS_CHECK)
+	ldo_mode_set(check_ldo_bypass());
+#endif
 #if defined(CONFIG_VIDEO_IPUV3)
 	/* disable video before launching O/S */
 	ipuv3_fb_shutdown();
diff --git a/arch/arm/include/asm/arch-mx6/sys_proto.h b/arch/arm/include/asm/arch-mx6/sys_proto.h
index 16c9b76..fe9103f 100644
--- a/arch/arm/include/asm/arch-mx6/sys_proto.h
+++ b/arch/arm/include/asm/arch-mx6/sys_proto.h
@@ -6,3 +6,13 @@
  */
 
 #include <asm/imx-common/sys_proto.h>
+
+void set_wdog_reset(struct wdog_regs *wdog);
+#ifdef CONFIG_LDO_BYPASS_CHECK
+int check_ldo_bypass(void);
+int check_1_2G(void);
+int set_anatop_bypass(int wdog_reset_pin);
+void ldo_mode_set(int ldo_bypass);
+void prep_anatop_bypass(void);
+void finish_anatop_bypass(void);
+#endif