u-boot/arch/x86/cpu/start.S

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/*
* U-Boot - x86 Startup Code
*
* (C) Copyright 2008-2011
* Graeme Russ, <graeme.russ@gmail.com>
*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <config.h>
#include <asm/global_data.h>
#include <asm/post.h>
#include <asm/processor.h>
#include <asm/processor-flags.h>
#include <generated/generic-asm-offsets.h>
#include <generated/asm-offsets.h>
.section .text
.code32
.globl _start
.type _start, @function
.globl _x86boot_start
_x86boot_start:
/*
* This is the fail-safe 32-bit bootstrap entry point.
*
* This code is used when booting from another boot loader like
* coreboot or EFI. So we repeat some of the same init found in
* start16.
*/
cli
cld
/* Turn off cache (this might require a 486-class CPU) */
movl %cr0, %eax
orl $(X86_CR0_NW | X86_CR0_CD), %eax
movl %eax, %cr0
wbinvd
/* Tell 32-bit code it is being entered from an in-RAM copy */
movl $GD_FLG_WARM_BOOT, %ebx
/*
* Zero the BIST (Built-In Self Test) value since we don't have it.
* It must be 0 or the previous loader would have reported an error.
*/
movl $0, %ebp
jmp 1f
/* Add a way for tools to discover the _start entry point */
.align 4
.long 0x12345678
_start:
/*
* This is the 32-bit cold-reset entry point, coming from start16.
* Set %ebx to GD_FLG_COLD_BOOT to indicate this.
*/
movl $GD_FLG_COLD_BOOT, %ebx
/* Save BIST */
movl %eax, %ebp
1:
/* Save table pointer */
movl %ecx, %esi
/* Load the segement registers to match the GDT loaded in start16.S */
movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
movw %ax, %fs
movw %ax, %ds
movw %ax, %gs
movw %ax, %es
movw %ax, %ss
/* Clear the interrupt vectors */
lidt blank_idt_ptr
/*
* Critical early platform init - generally not used, we prefer init
* to happen later when we have a console, in case something goes
* wrong.
*/
jmp early_board_init
.globl early_board_init_ret
early_board_init_ret:
post_code(POST_START)
/* Initialise Cache-As-RAM */
jmp car_init
.globl car_init_ret
car_init_ret:
#ifndef CONFIG_HAVE_FSP
/*
* We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
* or fully initialised SDRAM - we really don't care which)
* starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
* and early malloc() area. The MRC requires some space at the top.
*
* Stack grows down from top of CAR. We have:
*
* top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
x86: ivybridge: Implement SDRAM init Implement SDRAM init using the Memory Reference Code (mrc.bin) provided in the board directory and the SDRAM SPD information in the device tree. This also needs the Intel Management Engine (me.bin) to work. Binary blobs everywhere: so far we have MRC, ME and microcode. SDRAM init works by setting up various parameters and calling the MRC. This in turn does some sort of magic to work out how much memory there is and the timing parameters to use. It also sets up the DRAM controllers. When the MRC returns, we use the information it provides to map out the available memory in U-Boot. U-Boot normally moves itself to the top of RAM. On x86 the RAM is not generally contiguous, and anyway some RAM may be above 4GB which doesn't work in 32-bit mode. So we relocate to the top of the largest block of RAM we can find below 4GB. Memory above 4GB is accessible with special functions (see physmem). It would be possible to build U-Boot in 64-bit mode but this wouldn't necessarily provide any more memory, since the largest block is often below 4GB. Anyway U-Boot doesn't need huge amounts of memory - even a very large ramdisk seldom exceeds 100-200MB. U-Boot has support for booting 64-bit kernels directly so this does not pose a limitation in that area. Also there are probably parts of U-Boot that will not work correctly in 64-bit mode. The MRC is one. There is some work remaining in this area. Since memory init is very slow (over 500ms) it is possible to save the parameters in SPI flash to speed it up next time. Suspend/resume support is not fully implemented, or at least it is not efficient. With this patch, link boots to a prompt. Signed-off-by: Simon Glass <sjg@chromium.org>
2014-11-13 05:42:28 +00:00
* MRC area
* global_data
* x86 global descriptor table
* early malloc area
* stack
* bottom-> CONFIG_SYS_CAR_ADDR
*/
x86: ivybridge: Implement SDRAM init Implement SDRAM init using the Memory Reference Code (mrc.bin) provided in the board directory and the SDRAM SPD information in the device tree. This also needs the Intel Management Engine (me.bin) to work. Binary blobs everywhere: so far we have MRC, ME and microcode. SDRAM init works by setting up various parameters and calling the MRC. This in turn does some sort of magic to work out how much memory there is and the timing parameters to use. It also sets up the DRAM controllers. When the MRC returns, we use the information it provides to map out the available memory in U-Boot. U-Boot normally moves itself to the top of RAM. On x86 the RAM is not generally contiguous, and anyway some RAM may be above 4GB which doesn't work in 32-bit mode. So we relocate to the top of the largest block of RAM we can find below 4GB. Memory above 4GB is accessible with special functions (see physmem). It would be possible to build U-Boot in 64-bit mode but this wouldn't necessarily provide any more memory, since the largest block is often below 4GB. Anyway U-Boot doesn't need huge amounts of memory - even a very large ramdisk seldom exceeds 100-200MB. U-Boot has support for booting 64-bit kernels directly so this does not pose a limitation in that area. Also there are probably parts of U-Boot that will not work correctly in 64-bit mode. The MRC is one. There is some work remaining in this area. Since memory init is very slow (over 500ms) it is possible to save the parameters in SPI flash to speed it up next time. Suspend/resume support is not fully implemented, or at least it is not efficient. With this patch, link boots to a prompt. Signed-off-by: Simon Glass <sjg@chromium.org>
2014-11-13 05:42:28 +00:00
movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
#endif
#else
/*
* When we get here after car_init(), esp points to a temporary stack
* and esi holds the HOB list address returned by the FSP.
*/
#endif
/* Reserve space on stack for global data */
subl $GENERATED_GBL_DATA_SIZE, %esp
/* Align global data to 16-byte boundary */
andl $0xfffffff0, %esp
post_code(POST_START_STACK)
/*
* Debug UART is available here although it may not be plumbed out
* to pins depending on the board. To use it:
*
* call debug_uart_init
* mov $'a', %eax
* call printch
*/
/* Zero the global data since it won't happen later */
xorl %eax, %eax
movl $GENERATED_GBL_DATA_SIZE, %ecx
movl %esp, %edi
rep stosb
#ifdef CONFIG_HAVE_FSP
test %esi, %esi
jz skip_hob
/* Store HOB list */
movl %esp, %edx
addl $GD_HOB_LIST, %edx
movl %esi, (%edx)
skip_hob:
#else
/* Store table pointer */
movl %esp, %edx
addl $GD_TABLE, %edx
movl %esi, (%edx)
#endif
/* Setup first parameter to setup_gdt, pointer to global_data */
movl %esp, %eax
/* Reserve space for global descriptor table */
subl $X86_GDT_SIZE, %esp
/* Align temporary global descriptor table to 16-byte boundary */
andl $0xfffffff0, %esp
movl %esp, %ecx
#if defined(CONFIG_SYS_MALLOC_F_LEN)
/* Set up the pre-relocation malloc pool */
subl $CONFIG_SYS_MALLOC_F_LEN, %esp
movl %eax, %edx
addl $GD_MALLOC_BASE, %edx
movl %esp, (%edx)
#endif
/* Store BIST into global_data */
movl %eax, %edx
addl $GD_BIST, %edx
movl %ebp, (%edx)
/* Set second parameter to setup_gdt() */
movl %ecx, %edx
/* Setup global descriptor table so gd->xyz works */
call setup_gdt
/* Set parameter to board_init_f() to boot flags */
post_code(POST_START_DONE)
xorl %eax, %eax
/* Enter, U-Boot! */
call board_init_f
/* indicate (lack of) progress */
movw $0x85, %ax
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jmp die
.globl board_init_f_r_trampoline
.type board_init_f_r_trampoline, @function
board_init_f_r_trampoline:
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/*
* SDRAM has been initialised, U-Boot code has been copied into
* RAM, BSS has been cleared and relocation adjustments have been
* made. It is now time to jump into the in-RAM copy of U-Boot
*
* %eax = Address of top of new stack
2011-02-12 04:11:58 +00:00
*/
/* Stack grows down from top of SDRAM */
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movl %eax, %esp
/* Reserve space on stack for global data */
subl $GENERATED_GBL_DATA_SIZE, %esp
/* Align global data to 16-byte boundary */
andl $0xfffffff0, %esp
/* Setup first parameter to memcpy() and setup_gdt() */
movl %esp, %eax
/* Setup second parameter to memcpy() */
fs movl 0, %edx
/* Set third parameter to memcpy() */
movl $GENERATED_GBL_DATA_SIZE, %ecx
/* Copy global data from CAR to SDRAM stack */
call memcpy
/* Reserve space for global descriptor table */
subl $X86_GDT_SIZE, %esp
/* Align global descriptor table to 16-byte boundary */
andl $0xfffffff0, %esp
/* Set second parameter to setup_gdt() */
movl %esp, %edx
/* Setup global descriptor table so gd->xyz works */
call setup_gdt
/* Set if we need to disable CAR */
.weak car_uninit
movl $car_uninit, %eax
cmpl $0, %eax
jz 1f
call car_uninit
1:
/* Re-enter U-Boot by calling board_init_f_r() */
call board_init_f_r
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die:
hlt
jmp die
hlt
blank_idt_ptr:
.word 0 /* limit */
.long 0 /* base */
.p2align 2 /* force 4-byte alignment */
/* Add a multiboot header so U-Boot can be loaded by GRUB2 */
multiboot_header:
/* magic */
.long 0x1badb002
/* flags */
.long (1 << 16)
/* checksum */
.long -0x1BADB002 - (1 << 16)
/* header addr */
.long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
/* load addr */
.long CONFIG_SYS_TEXT_BASE
/* load end addr */
.long 0
/* bss end addr */
.long 0
/* entry addr */
.long CONFIG_SYS_TEXT_BASE