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/*
* Copyright (C) 2017, Bin Meng <bmeng.cn@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <asm/acpi_s3.h>
#include <asm/acpi_table.h>
#include <asm/post.h>
DECLARE_GLOBAL_DATA_PTR;
static void asmlinkage (*acpi_do_wakeup)(void *vector) = (void *)WAKEUP_BASE;
static void acpi_jump_to_wakeup(void *vector)
{
/* Copy wakeup trampoline in place */
memcpy((void *)WAKEUP_BASE, __wakeup, __wakeup_size);
printf("Jumping to OS waking vector %p\n", vector);
acpi_do_wakeup(vector);
}
void acpi_resume(struct acpi_fadt *fadt)
{
void *wake_vec;
/* Turn on ACPI mode for S3 */
enter_acpi_mode(fadt->pm1a_cnt_blk);
wake_vec = acpi_find_wakeup_vector(fadt);
/*
* Restore the memory content starting from address 0x1000 which is
* used for the real mode interrupt handler stubs.
*/
memcpy((void *)0x1000, (const void *)gd->arch.backup_mem,
S3_RESERVE_SIZE);
post_code(POST_OS_RESUME);
acpi_jump_to_wakeup(wake_vec);
}
int acpi_s3_reserve(void)
{
/* adjust stack pointer for ACPI S3 resume backup memory */
gd->start_addr_sp -= S3_RESERVE_SIZE;
gd->arch.backup_mem = gd->start_addr_sp;
gd->start_addr_sp &= ~0xf;
/*
* U-Boot sets up the real mode interrupt handler stubs starting from
* address 0x1000. In most cases, the first 640K (0x00000 - 0x9ffff)
* system memory is reported as system RAM in E820 table to the OS.
* (see install_e820_map() implementation for each platform). So OS
* can use these memories whatever it wants.
*
* If U-Boot is in an S3 resume path, care must be taken not to corrupt
* these memorie otherwise OS data gets lost. Testing shows that, on
* Microsoft Windows 10 on Intel Baytrail its wake up vector happens to
* be installed at the same address 0x1000. While on Linux its wake up
* vector does not overlap this memory range, but after resume kernel
* checks low memory range per config option CONFIG_X86_RESERVE_LOW
* which is 64K by default to see whether a memory corruption occurs
* during the suspend/resume (it's harmless, but warnings are shown
* in the kernel dmesg logs).
*
* We cannot simply mark the these memory as reserved in E820 table
* because such configuration makes GRUB complain: unable to allocate
* real mode page. Hence we choose to back up these memories to the
* place where we reserved on our stack for our S3 resume work.
* Before jumping to OS wake up vector, we need restore the original
* content there (see acpi_resume() above).
*/
if (gd->arch.prev_sleep_state == ACPI_S3)
memcpy((void *)gd->arch.backup_mem, (const void *)0x1000,
S3_RESERVE_SIZE);
return 0;
}
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