u-boot/board/raspberrypi/rpi/lowlevel_init.S

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * (C) Copyright 2016
 * Cédric Schieli <cschieli@gmail.com>
 */

#include <config.h>

/*
 * Routine: save_boot_params (called after reset from start.S)
 * Description: save ATAG/FDT address provided by the firmware at boot time
 */

.global save_boot_params
save_boot_params:

	/* The firmware provided ATAG/FDT address can be found in r2/x0 */
#ifdef CONFIG_ARM64
	adr	x8, fw_dtb_pointer
	str	x0, [x8]
#else
	ldr	r8, =fw_dtb_pointer
	str	r2, [r8]
#endif

	/* Returns */
	b	save_boot_params_ret
SPDX: Convert all of our single license tags to Linux Kernel style When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com> 2018-05-06 21:58:06 +00:00			`/* SPDX-License-Identifier: GPL-2.0+ */`
rpi: passthrough of the firmware provided FDT blob Raspberry firmware used to pass a FDT blob at a fixed address (0x100), but this is not true anymore. The address now depends on both the memory size and the blob size [1]. If one wants to passthrough this FDT blob to the kernel, the most reliable way is to save its address from the r2/x0 register in the U-Boot entry point and expose it in a environment variable for further processing. This patch just does this: - save the provided address in the global variable fw_dtb_pointer - expose it in ${fdt_addr} if it points to a a valid FDT blob There are many different ways to use it. One can, for example, use the following script which will extract from the tree the command line built by the firmware, then hand over the blob to a previously loaded kernel: fdt addr ${fdt_addr} fdt get value bootargs /chosen bootargs bootz ${kernel_addr_r} - ${fdt_addr} Alternatively, users relying on sysboot/pxe can simply omit any FDT statement in their extlinux.conf file, U-Boot will automagically pick ${fdt_addr} and pass it to the kernel. [1] https://www.raspberrypi.org/forums//viewtopic.php?f=107&t=134018 Signed-off-by: Cédric Schieli <cschieli@gmail.com> Acked-by: Stephen Warren <swarren@nvidia.com> 2016-11-11 10:59:07 +00:00			`/*`
			`* (C) Copyright 2016`
			`* Cédric Schieli <cschieli@gmail.com>`
			`*/`

			`#include <config.h>`

			`/*`
			`* Routine: save_boot_params (called after reset from start.S)`
			`* Description: save ATAG/FDT address provided by the firmware at boot time`
			`*/`

			`.global save_boot_params`
			`save_boot_params:`

			`/* The firmware provided ATAG/FDT address can be found in r2/x0 */`
			`#ifdef CONFIG_ARM64`
			`adr x8, fw_dtb_pointer`
			`str x0, [x8]`
			`#else`
rpi: push fw_dtb_pointer in the .data section The fw_dtb_pointer was defined in the assembly code, which makes him live in section .text_rest Put that's not necessary, we can push the variable in the .data section. This will prevent relocation errors like: board/raspberrypi/rpi/rpi.c:317:(.text.board_get_usable_ram_top+0x8): relocation truncated to fit: R_AARCH64_LDST64_ABS_LO12_NC against symbol `fw_dtb_pointer' defined in .text section in board/raspberrypi/rpi/built-in.o Signed-off-by: Matthias Brugger <mbrugger@suse.com> 2019-11-19 15:01:02 +00:00			`ldr r8, =fw_dtb_pointer`
			`str r2, [r8]`
rpi: passthrough of the firmware provided FDT blob Raspberry firmware used to pass a FDT blob at a fixed address (0x100), but this is not true anymore. The address now depends on both the memory size and the blob size [1]. If one wants to passthrough this FDT blob to the kernel, the most reliable way is to save its address from the r2/x0 register in the U-Boot entry point and expose it in a environment variable for further processing. This patch just does this: - save the provided address in the global variable fw_dtb_pointer - expose it in ${fdt_addr} if it points to a a valid FDT blob There are many different ways to use it. One can, for example, use the following script which will extract from the tree the command line built by the firmware, then hand over the blob to a previously loaded kernel: fdt addr ${fdt_addr} fdt get value bootargs /chosen bootargs bootz ${kernel_addr_r} - ${fdt_addr} Alternatively, users relying on sysboot/pxe can simply omit any FDT statement in their extlinux.conf file, U-Boot will automagically pick ${fdt_addr} and pass it to the kernel. [1] https://www.raspberrypi.org/forums//viewtopic.php?f=107&t=134018 Signed-off-by: Cédric Schieli <cschieli@gmail.com> Acked-by: Stephen Warren <swarren@nvidia.com> 2016-11-11 10:59:07 +00:00			`#endif`

			`/* Returns */`
			`b save_boot_params_ret`