| /* SPDX-License-Identifier: GPL-2.0-only */ |
| |
| #include <acpi/acpi.h> |
| #include <bootstate.h> |
| #include <commonlib/endian.h> |
| #include <types.h> |
| |
| #define X86_BDA_SIZE 0x200 |
| #define X86_BDA_BASE ((void *)0x400) |
| #define X86_EBDA_SEGMENT ((void *)0x40e) |
| #define X86_EBDA_LOWMEM ((void *)0x413) |
| |
| #define DEFAULT_EBDA_LOWMEM (1024 << 10) |
| #define DEFAULT_EBDA_SEGMENT 0xF600 |
| #define DEFAULT_EBDA_SIZE 0x400 |
| |
| |
| static void *get_ebda_start(void) |
| { |
| return (void *)((uintptr_t)DEFAULT_EBDA_SEGMENT << 4); |
| } |
| |
| /* |
| * EBDA area is representing a 1KB memory area just below |
| * the top of conventional memory (below 1MB) |
| */ |
| |
| static void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size) |
| { |
| u16 low_memory_kb; |
| u16 ebda_kb; |
| void *ebda; |
| |
| if (!low_memory_size || !ebda_segment || !ebda_size) |
| return; |
| |
| low_memory_kb = low_memory_size >> 10; |
| ebda_kb = ebda_size >> 10; |
| ebda = get_ebda_start(); |
| |
| /* clear BIOS DATA AREA */ |
| zero_n(X86_BDA_BASE, X86_BDA_SIZE); |
| |
| /* Avoid unaligned write16() since it's undefined behavior */ |
| write_le16(X86_EBDA_LOWMEM, low_memory_kb); |
| write_le16(X86_EBDA_SEGMENT, ebda_segment); |
| |
| /* Set up EBDA */ |
| zero_n(ebda, ebda_size); |
| write_le16(ebda, ebda_kb); |
| } |
| |
| static void setup_default_ebda(void *unused) |
| { |
| if (acpi_is_wakeup_s3()) |
| return; |
| |
| setup_ebda(DEFAULT_EBDA_LOWMEM, |
| DEFAULT_EBDA_SEGMENT, |
| DEFAULT_EBDA_SIZE); |
| } |
| |
| /* Ensure EBDA is prepared before Option ROMs. */ |
| BOOT_STATE_INIT_ENTRY(BS_DEV_INIT, BS_ON_ENTRY, setup_default_ebda, NULL); |