mirror of
https://source.denx.de/u-boot/u-boot.git
synced 2025-10-31 00:11:51 +01:00
12a3e1ada0
When u-boot is used as a chain-loaded bootloader (replacing OS kernel), previous bootloader leaves data in RAM, that can be reused. For example, on recent arm linux system, when chainloading u-boot, there are initramfs and fdt in RAM prepared for OS booting. Initramfs may be modified to store u-boot's payload, thus providing the ability to use chainloaded u-boot to boot OS without any storage support. Two config options added: - SAVE_PREV_BL_INITRAMFS_START_ADDR saves initramfs start address to 'prevbl_initrd_start_addr' environment variable - SAVE_PREV_BL_FDT_ADDR saves fdt address to 'prevbl_fdt_addr' environment variable Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com> Cc: Tom Rini <trini@konsulko.com>
92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* save_prev_bl_data - saving previous bootloader data
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* to environment variables.
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*
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* Copyright (c) 2022 Dzmitry Sankouski (dsankouski@gmail.com)
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*/
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#include <init.h>
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#include <env.h>
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#include <fdtdec.h>
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#include <fdt_support.h>
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#include <fdt.h>
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#include <common.h>
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#include <linux/errno.h>
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#include <asm/system.h>
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#include <asm/armv8/mmu.h>
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static ulong reg0 __section(".data");
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/**
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* Save x0 register value, assuming previous bootloader set it to
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* point on loaded fdt or (for older linux kernels)atags.
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*/
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void save_boot_params(ulong r0)
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{
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reg0 = r0;
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save_boot_params_ret();
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}
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bool is_addr_accessible(phys_addr_t addr)
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{
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struct mm_region *mem = mem_map;
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phys_addr_t bank_start;
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phys_addr_t bank_end;
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while (mem->size) {
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bank_start = mem->phys;
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bank_end = bank_start + mem->size;
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debug("check if block %pap - %pap includes %pap\n", &bank_start, &bank_end, &addr);
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if (addr > bank_start && addr < bank_end)
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return true;
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mem++;
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}
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return false;
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}
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int save_prev_bl_data(void)
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{
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struct fdt_header *fdt_blob;
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int node;
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u64 initrd_start_prop;
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if (!is_addr_accessible((phys_addr_t)reg0))
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return -ENODATA;
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fdt_blob = (struct fdt_header *)reg0;
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if (!fdt_valid(&fdt_blob)) {
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pr_warn("%s: address 0x%lx is not a valid fdt\n", __func__, reg0);
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return -ENODATA;
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}
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if (CONFIG_IS_ENABLED(SAVE_PREV_BL_FDT_ADDR))
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env_set_addr("prevbl_fdt_addr", (void *)reg0);
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if (!CONFIG_IS_ENABLED(SAVE_PREV_BL_INITRAMFS_START_ADDR))
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return 0;
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node = fdt_path_offset(fdt_blob, "/chosen");
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if (!node) {
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pr_warn("%s: chosen node not found in device tree at addr: 0x%lx\n",
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__func__, reg0);
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return -ENODATA;
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}
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/*
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* linux,initrd-start property might be either 64 or 32 bit,
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* depending on primary bootloader implementation.
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*/
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initrd_start_prop = fdtdec_get_uint64(fdt_blob, node, "linux,initrd-start", 0);
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if (!initrd_start_prop) {
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debug("%s: attempt to get uint64 linux,initrd-start property failed, trying uint\n",
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__func__);
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initrd_start_prop = fdtdec_get_uint(fdt_blob, node, "linux,initrd-start", 0);
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if (!initrd_start_prop) {
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debug("%s: attempt to get uint failed, too\n", __func__);
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return -ENODATA;
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}
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}
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env_set_addr("prevbl_initrd_start_addr", (void *)initrd_start_prop);
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return 0;
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}
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