imx: Add a common way for detecting NXP boards revision

NXP development boards based on i.MX6/i.MX7 contain the board
revision information stored in the fuses.

Introduce a common function that can be shared by different boards and
convert mx6sabreauto to use this new mechanism.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>

arch/arm/include/asm/mach-imx/sys_proto.h

@@ -109,6 +109,9 @@ void imx_wdog_disable_powerdown(void);
 
 int board_mmc_get_env_dev(int devno);
 
+int nxp_board_rev(void);
+char nxp_board_rev_string(void);
+
 /*
  * Initializes on-chip ethernet controllers.
  * to override, implement board_eth_init()

arch/arm/mach-imx/Kconfig

@@ -61,3 +61,11 @@ config CMD_HDMIDETECT
 	help
 	  This enables the 'hdmidet' command which detects if an HDMI monitor
 	  is connected.
+
+config NXP_BOARD_REVISION
+	bool "Read NXP board revision from fuses"
+	depends on ARCH_MX6 || ARCH_MX7
+	help
+	  NXP boards based on i.MX6/7 contain the board revision information
+	  stored in the fuses. Select this option if you want to be able to
+	  retrieve the board revision information.

arch/arm/mach-imx/cpu.c

@@ -323,3 +323,28 @@ void set_chipselect_size(int const cs_size)
 
 	writel(reg, &iomuxc_regs->gpr[1]);
 }
+
+#ifdef CONFIG_NXP_BOARD_REVISION
+int nxp_board_rev(void)
+{
+	/*
+	 * Get Board ID information from OCOTP_GP1[15:8]
+	 * RevA: 0x1
+	 * RevB: 0x2
+	 * RevC: 0x3
+	 */
+	struct ocotp_regs *ocotp = (struct ocotp_regs *)OCOTP_BASE_ADDR;
+	struct fuse_bank *bank = &ocotp->bank[4];
+	struct fuse_bank4_regs *fuse =
+			(struct fuse_bank4_regs *)bank->fuse_regs;
+
+	return (readl(&fuse->gp1) >> 8 & 0x0F);
+}
+
+char nxp_board_rev_string(void)
+{
+	const char *rev = "A";
+
+	return (*rev + nxp_board_rev() - 1);
+}
+#endif

board/freescale/mx6sabreauto/mx6sabreauto.c

@@ -397,39 +397,9 @@ int board_eth_init(bd_t *bis)
 	return cpu_eth_init(bis);
 }
 
-#define BOARD_REV_B  0x200
-#define BOARD_REV_A  0x100
-
-static int mx6sabre_rev(void)
-{
-	/*
-	 * Get Board ID information from OCOTP_GP1[15:8]
-	 * i.MX6Q ARD RevA: 0x01
-	 * i.MX6Q ARD RevB: 0x02
-	 */
-	struct ocotp_regs *ocotp = (struct ocotp_regs *)OCOTP_BASE_ADDR;
-	struct fuse_bank *bank = &ocotp->bank[4];
-	struct fuse_bank4_regs *fuse =
-			(struct fuse_bank4_regs *)bank->fuse_regs;
-	int reg = readl(&fuse->gp1);
-	int ret;
-
-	switch (reg >> 8 & 0x0F) {
-	case 0x02:
-		ret = BOARD_REV_B;
-		break;
-	case 0x01:
-	default:
-		ret = BOARD_REV_A;
-		break;
-	}
-
-	return ret;
-}
-
 u32 get_board_rev(void)
 {
-	int rev = mx6sabre_rev();
+	int rev = nxp_board_rev();
 
 	return (get_cpu_rev() & ~(0xF << 8)) | rev;
 }
@@ -703,20 +673,7 @@ int board_late_init(void)
 
 int checkboard(void)
 {
-	int rev = mx6sabre_rev();
-	char *revname;
-
-	switch (rev) {
-	case BOARD_REV_B:
-		revname = "B";
-		break;
-	case BOARD_REV_A:
-	default:
-		revname = "A";
-		break;
-	}
-
-	printf("Board: MX6Q-Sabreauto rev%s\n", revname);
+	printf("Board: MX6Q-Sabreauto rev%c\n", nxp_board_rev_string());
 
 	return 0;
 }

configs/mx6sabreauto_defconfig

@@ -8,6 +8,7 @@ CONFIG_SPL_MMC_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL_LIBDISK_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
+CONFIG_NXP_BOARD_REVISION=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/mach-imx/spl_sd.cfg"
 # CONFIG_CONSOLE_MUX is not set
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y