feat: boot original firmwares with default for the board layout

Support Ritmix boards at the moment.

config-rzx27.mk

@@ -14,5 +14,5 @@ BOARD := rzx27
 VARIANTS := mmc
 JZ_VERSION = 4725
 
-CFLAGS_all := -mips32
+CFLAGS_all := -mips32 -DTRY_ORIGINAL_FIRMWARE
 CFLAGS_mmc := -DHAVE_MBR

config-rzx50.mk

@@ -15,5 +15,5 @@ BOARD := rzx50
 VARIANTS := mmc
 JZ_VERSION = 4755
 
-CFLAGS_all := -mips32
+CFLAGS_all := -mips32 -DTRY_ORIGINAL_FIRMWARE
 CFLAGS_mmc := -DHAVE_MBR

src/board-rzx27.c

@@ -272,3 +272,28 @@ void nand_init(void)
 			   (EMC_STRV << EMC_SMCR_STRV_BIT);
 }
 #endif
+
+void original_firmware_load(void)
+{
+	// internal MSC0 shall be initialized first
+	// original firmware is at 256kiB offset on SD card.
+	// shall be loaded at 0x00800000 offset in RAM
+
+	const uint32_t load_addr = 0x00800000;
+	// load 1MiB bytes into RAM from 512 blocks (256kiB) offset on SD card.
+	if (!mmc_block_read(0, (void *) (KSEG1 + load_addr), 512, 2048)) {
+
+		SERIAL_PUTS("Trying original RZX-27 firmware from internal SD.\n");
+
+		// TODO check that loaded data not a crap
+		// reset the LCD controller for proper reintialization
+		__gpio_clear_pin(GPIOD, 21);
+		udelay(1000);
+		__gpio_set_pin(GPIOD, 21);
+
+		// jump into firmware
+		void (*entry)(void) = (void (*)(void))(KSEG1 + load_addr);
+		entry();
+		while (1);
+	}
+}

src/board-rzx50.c

@@ -324,3 +324,40 @@ void nand_init(void)
 			   (EMC_STRV << EMC_SMCR_STRV_BIT);
 }
 #endif
+
+#define	USB_BASE	0xB3040000
+
+#define REG_USB_FADDR	REG8(USB_BASE + 0x00) /* Function Address 8-bit */
+#define REG_USB_POWER	REG8(USB_BASE + 0x01) /* Power Managemetn 8-bit */
+
+void original_firmware_load(void)
+{
+	// internal MSC0 shall be initialized first
+	// original u-boot is at 16kiB offset on SD card.
+	// shall be loaded at 0x00100000 offset in RAM
+	// loading up to 1MiB is sufficient
+
+	const uint32_t load_addr = 0x00100000;
+	const uint32_t entry_offset = 0x200;
+
+	SERIAL_PUTS("Trying original RZX-50 firmware from internal SD.\n");
+
+	if (!mmc_block_read(0, (void *) (KSEG1 + load_addr), 32, 2048-32)) {
+		uint32_t cmd_1st = *(uint32_t*)(KSEG1 + load_addr + entry_offset);
+
+		//  first uboot command is always `bal 1f` => 0x04110002 in hex
+		if (cmd_1st != 0x04110002) {
+			SERIAL_PUTS("Unexpected content, booting might fail.\n");
+		}
+
+		/* reset USB to defaults, otherwise it won't work in original kernel.
+		 * starting UBIBoot over USB case */
+		REG_USB_POWER = 0x20;
+		REG_USB_FADDR = 0x80;
+
+		void (*entry)(void) = (void (*)(void))(KSEG1 + load_addr + entry_offset);
+		entry();
+		while (1);
+	}
+	SERIAL_PUTS("Can't read firmware from SD.\n");
+}

src/board.h

@@ -12,5 +12,9 @@ unsigned int get_memory_size(void);
 void nand_init(void);
 void nand_wait_ready(void);
 
+#ifdef TRY_ORIGINAL_FIRMWARE
+void original_firmware_load(void);
+#endif
+
 #endif
 

src/main.c

@@ -243,6 +243,15 @@ void c_main(void)
 		}
 	}
 
+#ifdef TRY_ORIGINAL_FIRMWARE
+	if (!exec_addr) {
+		for (unsigned i = 0; i < MMCS_COUNT; i++) {
+			/* MMC0 is internal usually on dual-MMC devices */
+			if (mmc_ids[i] == 0 && mmc_inited[i])
+				original_firmware_load();
+		}
+	}
+#endif
 	if (!exec_addr) {
 		SERIAL_PUTS("Unable to boot from SD."
 #ifdef USE_NAND