From fdf8724c1cc2c21d3786d11b889d16aafd57d842 Mon Sep 17 00:00:00 2001
From: Matheus <matheusuky@gmail.com>
Date: Thu, 20 Apr 2023 20:09:12 -0300
Subject: [PATCH] acpi: table parsing

---
 kernel-src/arch/x86-64/acpi.c         | 72 +++++++++++++++++++++++++++
 kernel-src/arch/x86-64/main.c         |  2 +
 kernel-src/include/x86-64/arch/acpi.h | 43 ++++++++++++++++
 3 files changed, 117 insertions(+)
 create mode 100644 kernel-src/arch/x86-64/acpi.c
 create mode 100644 kernel-src/include/x86-64/arch/acpi.h

diff --git a/kernel-src/arch/x86-64/acpi.c b/kernel-src/arch/x86-64/acpi.c
new file mode 100644
index 00000000..2af7e178
--- /dev/null
+++ b/kernel-src/arch/x86-64/acpi.c
@@ -0,0 +1,72 @@
+#include <arch/acpi.h>
+#include <limine.h>
+#include <logging.h>
+#include <kernel/alloc.h>
+#include <kernel/pmm.h>
+#include <string.h>
+
+static size_t headercount;
+static sdtheader_t **headers;
+
+static volatile struct limine_rsdp_request rsdpreq = {
+	.id = LIMINE_RSDP_REQUEST,
+	.revision = 0
+};
+
+bool acpi_checksumok(void *table) {
+	sdtheader_t *header = table;
+	uint8_t *ptr = table;
+	uint8_t sum = 0;
+	for (int i = 0; i < header->length; ++i)
+		sum += *ptr++;
+
+	return sum == 0;
+}
+
+void *acpi_findtable(char *sig, int n) {
+	for (size_t i = 0; i < headercount; ++i) {
+		if (headers[i] == NULL)
+			continue;
+
+		if (strncmp(sig, headers[i]->sig, 4) == 0) {
+			if (n-- == 0)
+				return headers[i];
+		}
+	}
+	return NULL;
+}
+
+void acpi_init() {
+	// FIXME search if no response
+	__assert(rsdpreq.response);
+	rsdp_t *rsdp = rsdpreq.response->address;
+
+	if (rsdp->revision == 0) {
+		printf("\e[93mACPI version 1.0 -- Using RSDT instead of XSDT.\e[0m\n");
+		rsdt_t *rsdt = MAKE_HHDM((rsdt_t *)(uint64_t)rsdp->rsdt);
+		__assert(acpi_checksumok(rsdt));
+		headercount = (rsdt->header.length - sizeof(sdtheader_t)) / sizeof(uint32_t);
+		headers = alloc(sizeof(sdtheader_t *) * headercount);
+		__assert(headers);
+
+		for (size_t i = 0; i < headercount; ++i) {
+			void *addr = MAKE_HHDM((void *)(uint64_t)rsdt->tables[i]);
+			if (acpi_checksumok(addr))
+				headers[i] = addr;
+		}
+	} else {
+		xsdt_t *xsdt = MAKE_HHDM((xsdt_t *)rsdp->xsdt);
+		__assert(acpi_checksumok(xsdt));
+		headercount = (xsdt->header.length - sizeof(sdtheader_t)) / sizeof(uint64_t);
+		headers = alloc(sizeof(sdtheader_t *) * headercount);
+		__assert(headers);
+
+		for (size_t i = 0; i < headercount; ++i) {
+			void *addr = MAKE_HHDM((void *)xsdt->tables[i]);
+			if (acpi_checksumok(addr))
+				headers[i] = addr;
+		}
+	}
+
+	printf("ACPI: %lu tables found\n", headercount);
+}
diff --git a/kernel-src/arch/x86-64/main.c b/kernel-src/arch/x86-64/main.c
index 51293e89..3b8b2016 100644
--- a/kernel-src/arch/x86-64/main.c
+++ b/kernel-src/arch/x86-64/main.c
@@ -9,6 +9,7 @@
 #include <kernel/vmm.h>
 #include <kernel/slab.h>
 #include <kernel/alloc.h>
+#include <arch/acpi.h>
 
 static cpu_t bsp_cpu;
 
@@ -24,5 +25,6 @@ void kernel_entry() {
 	arch_mmu_init();
 	vmm_init();
 	alloc_init();
+	acpi_init();
 	__assert(!"kernel entry end");
 }
diff --git a/kernel-src/include/x86-64/arch/acpi.h b/kernel-src/include/x86-64/arch/acpi.h
new file mode 100644
index 00000000..018a270d
--- /dev/null
+++ b/kernel-src/include/x86-64/arch/acpi.h
@@ -0,0 +1,43 @@
+#ifndef _ACPI_H
+#define _ACPI_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef struct {
+	char sig[8];
+	uint8_t checksum;
+	char oem[6];
+	uint8_t revision;
+	uint32_t rsdt;
+	uint32_t length;
+	uint64_t xsdt;
+	uint8_t xchecksum;
+	uint8_t reserved[3];
+} __attribute__((packed)) rsdp_t;
+
+typedef struct {
+	char sig[4];
+	uint32_t length;
+	uint8_t revision;
+	uint8_t cechksum;
+	char oemid[6];
+	char oemtableid[8];
+	uint32_t oemrevision;
+	uint32_t creatorrevision;
+} __attribute__((packed)) sdtheader_t;
+
+typedef struct {
+	sdtheader_t header;
+	uint64_t tables[];
+} __attribute__((packed)) xsdt_t;
+
+typedef struct {
+	sdtheader_t header;
+	uint32_t tables[];
+} __attribute__((packed)) rsdt_t;
+
+void acpi_init();
+
+#endif