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