rockchip: add option to change method of loading u-boot

If we would like to boot from SD card, we have to implement mmc driver
in SPL stage, and get a slightly large SPL binary. Rockchip SoC's
bootrom code has the ability to load spl and u-boot, then boot.

If CONFIG_ROCKCHIP_SPL_BACK_TO_BROM is enabled, the spl will return to
bootrom in board_init_f(), then bootrom loads u-boot binary.

Loading sequence after rework:
bootrom ==> spl ==> bootrom ==> u-boot

Signed-off-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
Fixed up spelling of U-Boot, boorom, opinion->option, Rochchip:
Signed-off-by: Simon Glass <sjg@chromium.org>

arch/arm/mach-rockchip/Kconfig

@@ -17,6 +17,14 @@ config ROCKCHIP_RK3036
 	  and video codec support. Peripherals include Gigabit Ethernet,
 	  USB2 host and OTG, SDIO, I2S, UART, SPI, I2C and PWMs.
 
+config ROCKCHIP_SPL_BACK_TO_BROM
+	bool "SPL returns to bootrom"
+	default y if ROCKCHIP_RK3036
+	help
+	  Rockchip SoCs have ability to load SPL & U-Boot binary. If enabled,
+          SPL will return to the boot rom, which will then load the U-Boot
+          binary to keep going on.
+
 source "arch/arm/mach-rockchip/rk3288/Kconfig"
 source "arch/arm/mach-rockchip/rk3036/Kconfig"
 endif

arch/arm/mach-rockchip/Makefile

@@ -7,6 +7,7 @@
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_ROCKCHIP_RK3288) += rk3288-board-spl.o
 obj-$(CONFIG_ROCKCHIP_RK3036) += rk3036-board-spl.o
+obj-$(CONFIG_ROCKCHIP_SPL_BACK_TO_BROM) += save_boot_param.o
 else
 obj-$(CONFIG_ROCKCHIP_RK3288) += board.o
 endif

arch/arm/mach-rockchip/board.c

@@ -10,12 +10,45 @@
 #include <ram.h>
 #include <asm/io.h>
 #include <asm/arch/clock.h>
+#include <asm/arch/periph.h>
+#include <asm/gpio.h>
+#include <dm/pinctrl.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
 int board_init(void)
 {
+#ifdef CONFIG_ROCKCHIP_SPL_BACK_TO_BROM
+	struct udevice *pinctrl;
+	int ret;
+
+    /*
+     * We need to implement sdcard iomux here for the further
+     * initlization, otherwise, it'll hit sdcard command sending
+     * timeout exception.
+     */
+	ret = uclass_get_device(UCLASS_PINCTRL, 0, &pinctrl);
+	if (ret) {
+		debug("%s: Cannot find pinctrl device\n", __func__);
+		goto err;
+	}
+	ret = pinctrl_request_noflags(pinctrl, PERIPH_ID_SDCARD);
+	if (ret) {
+		debug("%s: Failed to set up SD card\n", __func__);
+		goto err;
+	}
+
+	return 0;
+err:
+	printf("board_init: Error %d\n", ret);
+
+	/* No way to report error here */
+	hang();
+
+	return -1;
+#else
 	return 0;
+#endif
 }
 
 int dram_init(void)

arch/arm/mach-rockchip/rk3036/Makefile

@@ -10,4 +10,3 @@ obj-y += syscon_rk3036.o
 endif
 
 obj-y += sdram_rk3036.o
-obj-y += save_boot_param.o

arch/arm/mach-rockchip/rk3288-board-spl.c

@@ -149,7 +149,7 @@ static int configure_emmc(struct udevice *pinctrl)
 	return 0;
 }
 #endif
-
+extern void back_to_bootrom(void);
 void board_init_f(ulong dummy)
 {
 	struct udevice *pinctrl;
@@ -204,6 +204,9 @@ void board_init_f(ulong dummy)
 		debug("DRAM init failed: %d\n", ret);
 		return;
 	}
+#ifdef CONFIG_ROCKCHIP_SPL_BACK_TO_BROM
+	back_to_bootrom();
+#endif
 }
 
 static int setup_led(void)

arch/arm/mach-rockchip/save_boot_param.S

@@ -1,5 +1,5 @@
 /*
- * (C) Copyright 2015 Google, Inc
+ * (C) Copyright 2016 Rockchip Electronics Co., Ltd
  *
  * SPDX-License-Identifier:     GPL-2.0+
  */

doc/README.rockchip

@@ -119,6 +119,20 @@ something like:
    Hit any key to stop autoboot:  0
    =>
 
+The rockchip bootrom can load and boot an initial spl, then continue to
+load a second-level bootloader(ie. U-BOOT) as soon as it returns to bootrom.
+Therefore RK3288 has another loading sequence like RK3036. The option of
+U-Boot is controlled with this setting in U-Boot:
+
+	#define CONFIG_ROCKCHIP_SPL_BACK_TO_BROM
+
+You can create the image via the following operations:
+
+   ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \
+	firefly-rk3288/spl/u-boot-spl-dtb.bin out && \
+   cat firefly-rk3288/u-boot-dtb.bin >> out && \
+   sudo dd if=out of=/dev/sdc seek=64
+
 If you have an HDMI cable attached you should see a video console.
 
 For evb_rk3036 board:

include/configs/rk3288_common.h

@@ -33,7 +33,12 @@
 #define CONFIG_SYS_NS16550_MEM32
 #define CONFIG_SPL_BOARD_INIT
 
+#ifdef CONFIG_ROCKCHIP_SPL_BACK_TO_BROM
+/* Bootrom will load u-boot binary to 0x0 once return from SPL */
+#define CONFIG_SYS_TEXT_BASE		0x00000000
+#else
 #define CONFIG_SYS_TEXT_BASE		0x00100000
+#endif
 #define CONFIG_SYS_INIT_SP_ADDR		0x00100000
 #define CONFIG_SYS_LOAD_ADDR		0x00800800
 #define CONFIG_SPL_STACK		0xff718000