stm32f429: pass the device unique ID in DTB

Read device unique ID and set environment variable "serial#".
Value would then be passed to kernel through DTB.

To read ID from DTB, kernel is required to have commit:
3f599875e5202986b350618a617527ab441bf206 (ARM: 8355/1: arch: Show
the serial number from devicetree in cpuinfo)
This commit is already mainline since v4.1-rc1.

Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
To: Albert Aribaud <albert.u.boot@aribaud.net>
To: Tom Rini <trini@konsulko.com>
To: Kamil Lulko <rev13@wp.pl>
Cc: u-boot@lists.denx.de

arch/arm/include/asm/arch-stm32f4/stm32.h

@@ -14,6 +14,7 @@
 /*
  * Peripheral memory map
  */
+#define STM32_SYSMEM_BASE	0x1FFF0000
 #define STM32_PERIPH_BASE	0x40000000
 #define STM32_APB1PERIPH_BASE	(STM32_PERIPH_BASE + 0x00000000)
 #define STM32_APB2PERIPH_BASE	(STM32_PERIPH_BASE + 0x00010000)
@@ -25,6 +26,12 @@
 /*
  * Register maps
  */
+struct stm32_u_id_regs {
+	u32 u_id_low;
+	u32 u_id_mid;
+	u32 u_id_high;
+};
+
 struct stm32_rcc_regs {
 	u32 cr;		/* RCC clock control */
 	u32 pllcfgr;	/* RCC PLL configuration */
@@ -78,6 +85,9 @@ struct stm32_flash_regs {
 /*
  * Registers access macros
  */
+#define STM32_U_ID_BASE		(STM32_SYSMEM_BASE + 0x7A10)
+#define STM32_U_ID		((struct stm32_u_id_regs *)STM32_U_ID_BASE)
+
 #define STM32_RCC_BASE		(STM32_AHB1PERIPH_BASE + 0x3800)
 #define STM32_RCC		((struct stm32_rcc_regs *)STM32_RCC_BASE)
 

board/st/stm32f429-discovery/stm32f429-discovery.c

@@ -285,3 +285,22 @@ int board_init(void)
 
 	return 0;
 }
+
+#ifdef CONFIG_MISC_INIT_R
+int misc_init_r(void)
+{
+	char serialno[25];
+	uint32_t u_id_low, u_id_mid, u_id_high;
+
+	if (!getenv("serial#")) {
+		u_id_low  = readl(&STM32_U_ID->u_id_low);
+		u_id_mid  = readl(&STM32_U_ID->u_id_mid);
+		u_id_high = readl(&STM32_U_ID->u_id_high);
+		sprintf(serialno, "%08x%08x%08x",
+			u_id_high, u_id_mid, u_id_low);
+		setenv("serial#", serialno);
+	}
+
+	return 0;
+}
+#endif

include/configs/stm32f429-discovery.h

@@ -15,6 +15,7 @@
 #define CONFIG_OF_LIBFDT
 
 #define CONFIG_BOARD_EARLY_INIT_F
+#define CONFIG_MISC_INIT_R
 
 #define CONFIG_SYS_FLASH_BASE		0x08000000