LXR uboot/arch/x86/lib/acpi

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Copyright (C) 2017, Bin Meng <bmeng.cn@gmail.com>
   4 */
   5
   6#include <common.h>
   7#include <acpi_s3.h>
   8#include <asm/acpi.h>
   9#include <asm/acpi_table.h>
  10#include <asm/post.h>
  11#include <linux/linkage.h>
  12
  13DECLARE_GLOBAL_DATA_PTR;
  14
  15static void asmlinkage (*acpi_do_wakeup)(void *vector) = (void *)WAKEUP_BASE;
  16
  17static void acpi_jump_to_wakeup(void *vector)
  18{
  19        /* Copy wakeup trampoline in place */
  20        memcpy((void *)WAKEUP_BASE, __wakeup, __wakeup_size);
  21
  22        printf("Jumping to OS waking vector %p\n", vector);
  23        acpi_do_wakeup(vector);
  24}
  25
  26void acpi_resume(struct acpi_fadt *fadt)
  27{
  28        void *wake_vec;
  29
  30        /* Turn on ACPI mode for S3 */
  31        enter_acpi_mode(fadt->pm1a_cnt_blk);
  32
  33        wake_vec = acpi_find_wakeup_vector(fadt);
  34
  35        /*
  36         * Restore the memory content starting from address 0x1000 which is
  37         * used for the real mode interrupt handler stubs.
  38         */
  39        memcpy((void *)0x1000, (const void *)gd->arch.backup_mem,
  40               S3_RESERVE_SIZE);
  41
  42        post_code(POST_OS_RESUME);
  43        acpi_jump_to_wakeup(wake_vec);
  44}
  45
  46int acpi_s3_reserve(void)
  47{
  48        /* adjust stack pointer for ACPI S3 resume backup memory */
  49        gd->start_addr_sp -= S3_RESERVE_SIZE;
  50        gd->arch.backup_mem = gd->start_addr_sp;
  51
  52        gd->start_addr_sp &= ~0xf;
  53
  54        /*
  55         * U-Boot sets up the real mode interrupt handler stubs starting from
  56         * address 0x1000. In most cases, the first 640K (0x00000 - 0x9ffff)
  57         * system memory is reported as system RAM in E820 table to the OS.
  58         * (see install_e820_map() implementation for each platform). So OS
  59         * can use these memories whatever it wants.
  60         *
  61         * If U-Boot is in an S3 resume path, care must be taken not to corrupt
  62         * these memorie otherwise OS data gets lost. Testing shows that, on
  63         * Microsoft Windows 10 on Intel Baytrail its wake up vector happens to
  64         * be installed at the same address 0x1000. While on Linux its wake up
  65         * vector does not overlap this memory range, but after resume kernel
  66         * checks low memory range per config option CONFIG_X86_RESERVE_LOW
  67         * which is 64K by default to see whether a memory corruption occurs
  68         * during the suspend/resume (it's harmless, but warnings are shown
  69         * in the kernel dmesg logs).
  70         *
  71         * We cannot simply mark the these memory as reserved in E820 table
  72         * because such configuration makes GRUB complain: unable to allocate
  73         * real mode page. Hence we choose to back up these memories to the
  74         * place where we reserved on our stack for our S3 resume work.
  75         * Before jumping to OS wake up vector, we need restore the original
  76         * content there (see acpi_resume() above).
  77         */
  78        if (gd->arch.prev_sleep_state == ACPI_S3)
  79                memcpy((void *)gd->arch.backup_mem, (const void *)0x1000,
  80                       S3_RESERVE_SIZE);
  81
  82        return 0;
  83}
  84