rulimine/stage23/lib/acpi.c
2021-03-10 02:27:26 +01:00

102 lines
2.6 KiB
C

#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <lib/acpi.h>
#include <lib/blib.h>
#include <lib/libc.h>
#include <lib/print.h>
// Following function based on https://github.com/managarm/lai/blob/master/helpers/pc-bios.c's function lai_bios_calc_checksum()
uint8_t acpi_checksum(void *ptr, size_t size) {
uint8_t sum = 0, *_ptr = ptr;
for (size_t i = 0; i < size; i++)
sum += _ptr[i];
return sum;
}
#if defined (bios)
void *acpi_get_rsdp(void) {
size_t ebda = EBDA;
for (size_t i = ebda; i < 0x100000; i += 16) {
if (i == ebda + 1024) {
// We probed the 1st KiB of the EBDA as per spec, move onto 0xe0000
i = 0xe0000;
}
if (!memcmp((char *)i, "RSD PTR ", 8)
&& !acpi_checksum((void *)i, sizeof(struct rsdp))) {
print("acpi: Found RSDP at %x\n", i);
return (void *)i;
}
}
return NULL;
}
#endif
#if defined (uefi)
#include <efi.h>
void *acpi_get_rsdp(void) {
for (size_t i = 0; i < gST->NumberOfTableEntries; i++) {
EFI_CONFIGURATION_TABLE *cur_table = &gST->ConfigurationTable[i];
EFI_GUID acpi_2_guid = ACPI_20_TABLE_GUID;
if (memcmp(&cur_table->VendorGuid, &acpi_2_guid, sizeof(EFI_GUID)) != 0)
continue;
if (acpi_checksum(cur_table->VendorTable, sizeof(struct rsdp)) != 0)
continue;
print("acpi: Found RSDP at %X\n", cur_table->VendorTable);
return (void *)cur_table->VendorTable;
}
return NULL;
}
#endif
void *acpi_get_table(const char *signature, int index) {
int cnt = 0;
struct rsdp_rev2 *rsdp = acpi_get_rsdp();
if (rsdp == NULL)
return NULL;
bool use_xsdt = false;
if (rsdp->rev >= 2 && rsdp->xsdt_addr)
use_xsdt = true;
struct rsdt *rsdt;
if (use_xsdt)
rsdt = (struct rsdt *)(uintptr_t)rsdp->xsdt_addr;
else
rsdt = (struct rsdt *)(uintptr_t)rsdp->rsdt_addr;
size_t entry_count =
(rsdt->length - sizeof(struct sdt)) / (use_xsdt ? 8 : 4);
for (size_t i = 0; i < entry_count; i++) {
struct sdt *ptr;
if (use_xsdt)
ptr = (struct sdt *)(uintptr_t)((uint64_t *)rsdt->ptrs_start)[i];
else
ptr = (struct sdt *)(uintptr_t)((uint32_t *)rsdt->ptrs_start)[i];
if (!memcmp(ptr->signature, signature, 4)
&& !acpi_checksum(ptr, ptr->length)
&& cnt++ == index) {
print("acpi: Found \"%s\" at %x\n", signature, ptr);
return ptr;
}
}
print("acpi: \"%s\" not found\n", signature);
return NULL;
}