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https://github.com/AsahiLinux/u-boot
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8e1c9fe243
This adds a boot method for loading the next stage from the host. It is mostly modeled off of spl_load_image_ext. I am not really sure why/how spl_load_image_fat uses three different methods to load the image, but the simple case seems to work OK for now. To control the presence of this boot method, we add a config symbol. While we're at it, we update the original semihosting config symbol. I think semihosting has some advantages of other forms of JTAG boot. Common other ways to boot from JTAG include: - Implementing DDR initialization through JTAG (typically with dozens of lines of TCL) and then loading U-Boot. The DDR initialization typically uses hard-coded register writes, and is not easily adapted to different boards. BOOT_DEVICE_SMH allows booting with SPL, leveraging U-Boot's existing DDR initialization code. This is the method used by NXP's CodeWarrior IDE on Layerscape processors (see AN12270). - Loading a bootloader into SDRAM, waiting for it to initialize DDR, and then loading U-Boot. This is tricky, because the debugger must stop the boot after the bootloader has completed its work. Trying to load U-Boot too early can cause failure to boot. This is the method used by Xilinx with its Zynq(MP) processors. - Loading SPL with BOOT_DEVICE_RAM and breaking before SPL loads the image to load U-Boot at the appropriate place. This can be a bit tricky, because the load address is dependent on the header size. An elf with symbols must also be used in order to stop at the appropriate point. BOOT_DEVICE_SMH can be viewed as an extension of this process, where SPL automatically stops and tells the host where to place the image. Signed-off-by: Sean Anderson <sean.anderson@seco.com>
45 lines
837 B
C
45 lines
837 B
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* (C) Copyright 2012
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* Texas Instruments, <www.ti.com>
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*/
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#ifndef _ASM_SPL_H_
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#define _ASM_SPL_H_
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#if defined(CONFIG_ARCH_OMAP2PLUS) \
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|| defined(CONFIG_EXYNOS4) || defined(CONFIG_EXYNOS5) \
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|| defined(CONFIG_EXYNOS4210) || defined(CONFIG_ARCH_K3)
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/* Platform-specific defines */
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#include <asm/arch/spl.h>
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#else
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enum {
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BOOT_DEVICE_RAM,
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BOOT_DEVICE_MMC1,
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BOOT_DEVICE_MMC2,
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BOOT_DEVICE_MMC2_2,
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BOOT_DEVICE_NAND,
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BOOT_DEVICE_ONENAND,
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BOOT_DEVICE_NOR,
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BOOT_DEVICE_UART,
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BOOT_DEVICE_SPI,
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BOOT_DEVICE_USB,
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BOOT_DEVICE_SATA,
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BOOT_DEVICE_I2C,
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BOOT_DEVICE_BOARD,
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BOOT_DEVICE_DFU,
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BOOT_DEVICE_XIP,
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BOOT_DEVICE_BOOTROM,
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BOOT_DEVICE_SMH,
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BOOT_DEVICE_NONE
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};
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#endif
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/* Linker symbols. */
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extern char __bss_start[], __bss_end[];
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#ifndef CONFIG_DM
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extern gd_t gdata;
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#endif
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#endif
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