1 files changed, 68 insertions, 0 deletions
diff --git a/src/kernel/arch/amd64/acpi.c b/src/kernel/arch/amd64/acpi.c
new file mode 100644
index 0000000..cc7791f
--- /dev/null
+++ b/src/kernel/arch/amd64/acpi.c
@@ -0,0 +1,68 @@
+#include <kernel/arch/amd64/acpi.h>
+#include <kernel/panic.h>
+#include <shared/mem.h>
+#include <stdint.h>
+
+typedef struct {
+	char sig[8];
+	uint8_t checksum;
+	char oemid[6];
+	uint8_t rev;
+	uint32_t rsdt;
+} __attribute__((packed)) RDSP;
+
+typedef struct {
+	char sig[4];
+	uint32_t len;
+	uint8_t rev;
+	uint8_t checksum;
+	char oemID[6];
+	char oemTID[8];
+	uint32_t oemRev;
+	uint32_t creatorId;
+	uint32_t creatorRev;
+	char data[0];
+} __attribute__((packed)) SDT;
+
+/* https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf */
+typedef struct {
+	uint8_t where;
+	uint8_t bitwidth;
+	uint8_t bitoffset;
+	uint8_t _reserved;
+	uint64_t addr;
+} __attribute__((packed)) GAS; /* Generic Address Structure */
+
+typedef struct {
+	SDT hdr;
+	uint32_t _someid;
+	GAS addr;
+	/* ... */
+} __attribute__((packed)) HPET;
+
+void
+acpi_parse(const void *rdsp_v)
+{
+	const RDSP *rdsp = rdsp_v;
+	if (memcmp(rdsp->sig, "RSD PTR ", 8) != 0) {
+		panic_invalid_state();
+	}
+
+	SDT *rsdt = (void*)(uintptr_t)rdsp->rsdt;
+	if (memcmp(rsdt->sig, "RSDT ", 4) != 0) {
+		panic_invalid_state();
+	}
+
+	uint32_t *sub = (void*)rsdt->data;
+	int len = (rsdt->len - sizeof(SDT)) / 4;
+	for (int i = 0; i < len; i++) {
+		SDT *it = (void*)(uintptr_t)sub[i];
+		if (memcmp(it->sig, "HPET", 4) == 0) {
+			HPET *hpet = (void*)it;
+			GAS *gas = &hpet->addr;
+			if (gas->where == 0) { /* in memory */
+				hpet_init((void*)gas->addr);
+			}
+		}
+	}
+}