1 files changed, 89 insertions, 0 deletions
diff --git a/src/acpi.c b/src/acpi.c
new file mode 100644
index 0000000..5cee000
--- /dev/null
+++ b/src/acpi.c
@@ -0,0 +1,89 @@
+#include "aplos.h"
+
+enum {
+	SDT_HEADER_SIZE = 36,
+	SDT_LENGTH_OFFSET = 4,
+
+	RSDT_VERSION_OFFSET = 15,
+	RSDT_VENDOR_OFFSET = 9,
+	RSDT_VENDOR_SIZE = 6,
+	RSDT_RSDP_OFFSET = 16
+};
+
+static uint8_t *rsdp;
+static uint8_t *rsdt;
+static uint8_t *madt;
+
+static void parse_rsdt(uint64_t);
+static void parse_madt(struct ioapic_info *);
+static uint8_t *map_sdt(uint64_t);
+
+void
+setup_acpi(uint64_t rsdp_physical, struct ioapic_info *ioapic)
+{
+	rsdp = (uint8_t *)map_page(rsdp_physical, 1, true);
+	uint8_t version = rsdp[RSDT_VERSION_OFFSET];
+	char8_t vendor[RSDT_VENDOR_SIZE+1];
+	memcpy(vendor, rsdp+RSDT_VENDOR_OFFSET, RSDT_VENDOR_SIZE);	
+	vendor[RSDT_VENDOR_SIZE] = 0;
+
+	switch(version){
+	case 0:
+		parse_rsdt(read_uint32_le(rsdp+RSDT_RSDP_OFFSET));
+		break;
+	default:
+		print(u8"Unknown RSDP version :(\n");
+		panic();
+	}
+
+	parse_madt(ioapic);
+}
+
+void
+parse_rsdt(uint64_t rsdt_physical)
+{
+	rsdt = map_sdt(rsdt_physical);
+	uint32_t length = read_uint32_le(rsdt+SDT_LENGTH_OFFSET);
+	uint32_t entries = (length - SDT_HEADER_SIZE) / 4;
+
+	uint32_t *ptrs = (uint32_t *)(((uint64_t)rsdt)+SDT_HEADER_SIZE);
+	for(uint32_t i = 0; i < entries; i++){
+		uint8_t *ptr = map_sdt(ptrs[i]);
+		if(utf8_cmp_n(ptr, u8"APIC", 4) == 0)
+			madt = ptr;
+	}
+}
+
+void
+parse_madt(struct ioapic_info *ioapic)
+{
+	assert(madt != NULL);
+
+	uint32_t length = read_uint32_le(madt+SDT_LENGTH_OFFSET);
+	uint32_t offset = SDT_HEADER_SIZE + 8;
+	while(offset < length){
+		uint8_t type = madt[offset];
+		uint8_t record_length = madt[offset+1];
+		switch(type){
+		case 1:
+			/* I/O APIC */
+			ioapic->base = read_uint32_le(madt+offset+4);
+			ioapic->interrupt_base = read_uint32_le(madt+offset+8);
+			break;
+		}
+		offset += record_length;
+	}
+}
+
+static uint8_t *
+map_sdt(uint64_t sdt_physical)
+{
+	uint8_t *p = (uint8_t *)map_page(sdt_physical, 1, true);	
+	uint32_t length = read_uint32_le(p+4);
+	uint32_t pages = (length + PAGE_SIZE - 1) / PAGE_SIZE;
+	if(pages > 1){
+		/* Remap the thing */
+		p = (uint8_t *)map_page(sdt_physical, pages, true);
+	}
+	return p;
+}