arm: mvebu: Implement return_to_bootrom() via U-Boot's SPL framework

U-Boot's SPL framework already has an API for loading U-Boot via
BootROM.

Implement the function board_return_to_bootrom() for mvebu SPL code.
Signed-off-by: NPali Rohár <pali@kernel.org>
Reviewed-by: NMarek Behún <marek.behun@nic.cz>
Reviewed-by: NStefan Roese <sr@denx.de>
Reviewed-by: NChris Packham <judge.packham@gmail.com>
Tested-by: NChris Packham <judge.packham@gmail.com>

arch/arm/mach-mvebu/Kconfig

@@ -257,6 +257,7 @@ config MVEBU_SPL_BOOT_DEVICE_SPI
 	select SPL_SPI_FLASH_SUPPORT
 	select SPL_SPI_LOAD
 	select SPL_SPI_SUPPORT
+	select SPL_BOOTROM_SUPPORT
 
 config MVEBU_SPL_BOOT_DEVICE_MMC
 	bool "SDIO/MMC card"
@@ -267,14 +268,17 @@ config MVEBU_SPL_BOOT_DEVICE_MMC
 	select SPL_GPIO
 	select SPL_LIBDISK_SUPPORT
 	select SPL_MMC_SUPPORT
+	select SPL_BOOTROM_SUPPORT
 
 config MVEBU_SPL_BOOT_DEVICE_SATA
 	bool "SATA"
 	select SPL_SATA_SUPPORT
 	select SPL_LIBDISK_SUPPORT
+	select SPL_BOOTROM_SUPPORT
 
 config MVEBU_SPL_BOOT_DEVICE_UART
 	bool "UART"
+	select SPL_BOOTROM_SUPPORT
 
 endchoice
 

arch/arm/mach-mvebu/spl.c

@@ -79,6 +79,18 @@ u32 spl_boot_device(void)
 	return get_boot_device();
 }
 
+int board_return_to_bootrom(struct spl_image_info *spl_image,
+			    struct spl_boot_device *bootdev)
+{
+	u32 *regs = *(u32 **)CONFIG_SPL_BOOTROM_SAVE;
+
+	printf("Returning to BootROM (return address 0x%08x)...\n", regs[13]);
+	return_to_bootrom();
+
+	/* NOTREACHED - return_to_bootrom() does not return */
+	hang();
+}
+
 void board_init_f(ulong dummy)
 {
 	int ret;