x86_64: add a basic ACPI driver

arch/x86_64/acpi/acpi.c

@@ -0,0 +1,9 @@
+#include <arch/acpi.h>
+#include <socks/printk.h>
+
+kern_status_t acpi_init(void)
+{
+	struct acpi_sdt *fadt = acpi_find_sdt(ACPI_SIG_FADT);
+	printk("acpi: FADT=%p", fadt);
+	return KERN_OK;
+}

arch/x86_64/acpi/rsdp.c

@@ -0,0 +1,102 @@
+#include <arch/acpi.h>
+#include <socks/vm.h>
+#include <socks/printk.h>
+#include <stddef.h>
+
+static struct acpi_rsdp rsdp;
+
+static struct acpi_rsdp_10 *search_for_rsdp(void)
+{
+	uint64_t *start = vm_phys_to_virt(0x80000);
+	uint64_t *end = vm_phys_to_virt(0xFFFFF);
+	
+	for (uint64_t *i = start; i < end; i++) {
+		if (*i == ACPI_SIG_RSDP) {
+			return (struct acpi_rsdp_10 *)i;
+		}
+	}
+
+	return NULL;
+}
+
+static int init_rsdt(void)
+{
+	struct acpi_rsdp_10 *x = search_for_rsdp();
+
+	if (!x) {
+		printk("acpi: not available");
+		return -1;
+	}
+
+	uint8_t *b = (uint8_t *)x;
+	size_t chksum = 0;
+	for (unsigned int i = 0; i < sizeof *x; i++) {
+		chksum += b[i];
+	}
+		
+	if (chksum & 0xFF) {
+		printk("acpi: not available");
+		return -1;
+	}
+
+	if (x->r_revision == 2) {
+		chksum = 0;
+		
+		for (unsigned int i = sizeof *x; i < sizeof(struct acpi_rsdp_20); i++) {
+			chksum += b[i];
+		}
+
+		if (chksum & 0xFF) {
+		    printk("acpi: not available");
+		    return -1;
+		}
+	}
+		
+	memcpy(&rsdp.rsdp_20, x, sizeof rsdp.rsdp_20);
+	return 0;
+}
+
+static struct acpi_sdt *find_via_rsdt(uint32_t sig)
+{
+	struct acpi_rsdt *rsdt = vm_phys_to_virt(rsdp.rsdp_10.r_rsdt_ptr);
+	unsigned long nr_tables = (rsdt->r_header.s_length - sizeof(struct acpi_sdt)) / sizeof(uint32_t);
+
+	for (unsigned long i = 0; i < nr_tables; i++) {
+		struct acpi_sdt *table = vm_phys_to_virt(rsdt->r_tables[i]);
+		if (*(uint32_t *)table == sig) {
+			return table;
+		}
+	}
+
+	return NULL;
+}
+
+static struct acpi_sdt *find_via_xsdt(uint32_t sig)
+{
+	struct acpi_xsdt *xsdt = vm_phys_to_virt(rsdp.rsdp_20.r_xsdt_ptr);
+	unsigned long nr_tables = (xsdt->x_header.s_length - sizeof(struct acpi_sdt)) / sizeof(uint64_t);
+
+	for (unsigned long i = 0; i < nr_tables; i++) {
+		struct acpi_sdt *table = vm_phys_to_virt(xsdt->x_tables[i]);
+		if (*(uint32_t *)table == sig) {
+			return table;
+		}
+	}
+
+	return NULL;
+}
+
+struct acpi_sdt *acpi_find_sdt(uint32_t sig)
+{
+	if (!rsdp.rsdp_10.r_sig[0]) {
+		if (init_rsdt() != 0) {
+			return NULL;
+		}
+	}
+
+	if (rsdp.rsdp_10.r_revision == 0) {
+		return find_via_rsdt(sig);
+	} else {
+		return find_via_xsdt(sig);
+	}
+}

arch/x86_64/config.mk

@@ -1,2 +1,8 @@
 ARCH_CFLAGS := -z max-page-size=0x1000 -m64 -mcmodel=large -mno-red-zone -mno-mmx -mno-sse -mno-sse2 -D_64BIT -DBYTE_ORDER=1234
 ARCH_LDFLAGS := -z max-page-size=0x1000 -T arch/x86_64/layout.ld
+
+ARCH_DIR := arch/$(ARCH)
+
+ARCH_C_FILES := $(wildcard $(ARCH_DIR)/*.c) $(wildcard $(ARCH_DIR)/acpi/*.c)
+ARCH_ASM_FILES := $(wildcard $(ARCH_DIR)/*.S)
+ARCH_OBJ := $(addprefix $(BUILD_DIR)/,$(ARCH_C_FILES:.c=.o) $(ARCH_ASM_FILES:.S=.o))

arch/x86_64/include/arch/acpi.h

@@ -0,0 +1,61 @@
+#ifndef ARCH_ACPI_H_
+#define ARCH_ACPI_H_
+
+#include <socks/compiler.h>
+#include <socks/status.h>
+#include <stdint.h>
+
+#define ACPI_SIG_RSDP 0x2052545020445352ULL
+#define ACPI_SIG_FADT 0x50434146
+
+struct acpi_rsdp_10 {
+	char r_sig[8];
+	uint8_t r_chksum;
+	char r_oem[6];
+	uint8_t r_revision;
+	uint32_t r_rsdt_ptr;
+} __packed;
+
+struct acpi_rsdp_20 {
+	struct acpi_rsdp_10 r_base;
+
+	uint32_t r_length;
+	uint64_t r_xsdt_ptr;
+	uint8_t r_chksum_ext;
+	uint8_t r_reserved[3];
+} __packed;
+
+struct acpi_rsdp {
+	union {
+		struct acpi_rsdp_10 rsdp_10;
+		struct acpi_rsdp_20 rsdp_20;
+	};
+} __packed;
+		  
+struct acpi_sdt {
+	char s_sig[4];
+	uint32_t s_length;
+	uint8_t s_revision;
+	uint8_t s_chksum;
+	char s_oem[6];
+	char s_oem_table[8];
+	uint32_t s_oem_revision;
+	uint32_t s_creator;
+	uint32_t s_creator_revision;
+} __packed;
+
+struct acpi_rsdt {
+	struct acpi_sdt r_header;
+	uint32_t r_tables[];
+} __packed;
+
+struct acpi_xsdt {
+	struct acpi_sdt x_header;
+	uint64_t x_tables[];
+} __packed;
+
+extern kern_status_t acpi_init(void);
+
+extern struct acpi_sdt *acpi_find_sdt(uint32_t sig);
+
+#endif

arch/x86_64/init.c

@@ -7,6 +7,7 @@
 #include <socks/printk.h>
 #include <socks/machine/cpu.h>
 #include <arch/vgacon.h>
+#include <arch/acpi.h>
 
 #define PTR32(x) ((void *)((uintptr_t)(x)))
 
@@ -51,6 +52,8 @@ int ml_init(uintptr_t arg)
 
 	pmap_bootstrap();
 
+	acpi_init();
+
 	vm_zone_descriptor_t vm_zones[] = {
 		{ .zd_id = VM_ZONE_DMA, .zd_node = 0, .zd_name = "dma", .zd_base = 0x00, .zd_limit = 0xffffff },
 		{ .zd_id = VM_ZONE_NORMAL, .zd_node = 0, .zd_name = "normal", .zd_base = 0x1000000, .zd_limit = UINTPTR_MAX },