SPDX: Convert all of our single license tags to Linux Kernel style

[u-boot] / arch / x86 / lib / acpi_s3.c

diff --git a/arch/x86/lib/acpi_s3.c b/arch/x86/lib/acpi_s3.c
index e5cc3b07664984845e0c61da1ac973de608c3970..514b92ffbd1235ced935b541cc26e7e5860357fb 100644 (file)
--- a/arch/x86/lib/acpi_s3.c
+++ b/arch/x86/lib/acpi_s3.c
@@ -1,13 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * 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>
+#include <linux/linkage.h>
+
+DECLARE_GLOBAL_DATA_PTR;
 
 static void asmlinkage (*acpi_do_wakeup)(void *vector) = (void *)WAKEUP_BASE;
 
@@ -24,8 +26,57 @@ 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;
+}