feat/kernel: Re-add ACPI

kernel/src/emk.c

@@ -18,6 +18,7 @@
 #include <flanterm/backends/fb.h>
 #endif // FLANTERM_SUPPORT
 #include <arch/smp.h>
+#include <sys/acpi.h>
 
 __attribute__((used, section(".limine_requests"))) static volatile LIMINE_BASE_REVISION(3);
 __attribute__((used, section(".limine_requests"))) static volatile struct limine_memmap_request memmap_request = {
@@ -166,6 +167,14 @@ void emk_entry(void)
     *c = 32;
     kfree(c);
 
+    /* Setup ACPI (and TODO APIC) */
+    rsdp_response = rsdp_request.response;
+    if (!rsdp_response)
+    {
+        kpanic(NULL, "Failed to get RSDP request");
+    }
+    acpi_init();
+
     /* Finished */
     log_early("%s", LOG_SEPARATOR);
     uint32_t uptime = 0;

kernel/src/sys/acpi.c

@@ -0,0 +1,65 @@
+/* EMK 1.0 Copyright (c) 2025 Piraterna */
+#include <sys/acpi.h>
+#include <boot/emk.h>
+#include <lib/string.h>
+#include <util/log.h>
+#include <sys/kpanic.h>
+#include <mm/vmm.h>
+
+static int acpi_uses_xsdt = 0;
+static void *acpi_rsdt_ptr = NULL;
+
+void acpi_init(void)
+{
+    if (!rsdp_response || !rsdp_response->address)
+    {
+        kpanic(NULL, "No RSDP provided");
+    }
+
+    acpi_rsdp_t *rsdp = (acpi_rsdp_t *)vallocat(kvm_ctx, 1, VALLOC_RW, rsdp_response->address);
+
+    if (memcmp(rsdp->signature, "RSD PTR", 7) != 0)
+        kpanic(NULL, "Invalid RSDP signature!");
+
+    if (rsdp->revision != 0)
+    {
+        acpi_uses_xsdt = 1;
+        acpi_xsdp_t *xsdp = (acpi_xsdp_t *)rsdp;
+        acpi_rsdt_ptr = (acpi_xsdt_t *)HIGHER_HALF(xsdp->xsdt_address);
+        log_early("XSDT found at %p", acpi_rsdt_ptr);
+        return;
+    }
+
+    acpi_rsdt_ptr = (acpi_rsdt_t *)HIGHER_HALF(rsdp->rsdt_address);
+    log_early("RSDT found at %p", acpi_rsdt_ptr);
+}
+
+void *acpi_find_table(const char *name)
+{
+    if (!acpi_uses_xsdt)
+    {
+        acpi_rsdt_t *rsdt = (acpi_rsdt_t *)acpi_rsdt_ptr;
+        uint32_t entries = (rsdt->sdt.length - sizeof(rsdt->sdt)) / 4;
+        for (uint32_t i = 0; i < entries; i++)
+        {
+            acpi_sdt_header_t *sdt = (acpi_sdt_header_t *)HIGHER_HALF(*((uint32_t *)rsdt->table + i));
+            if (!memcmp(sdt->signature, name, 4))
+                return (void *)sdt;
+        }
+        return NULL;
+    }
+    acpi_xsdt_t *xsdt = (acpi_xsdt_t *)acpi_rsdt_ptr;
+    log_early("XSDT address: %p", xsdt);
+    uint32_t entries = (xsdt->sdt.length - sizeof(xsdt->sdt)) / 8;
+
+    for (uint32_t i = 0; i < entries; i++)
+    {
+        acpi_sdt_header_t *sdt = (acpi_sdt_header_t *)HIGHER_HALF(*((uint64_t *)xsdt->table + i));
+        if (!memcmp(sdt->signature, name, 4))
+        {
+            return (void *)sdt;
+        }
+    }
+
+    return NULL;
+}

kernel/src/sys/acpi.h

@@ -0,0 +1,60 @@
+/* EMK 1.0 Copyright (c) 2025 Piraterna */
+#ifndef ACPI_H
+#define ACPI_H
+
+#include <stdint.h>
+#include <stddef.h>
+#include <lib/string.h>
+
+typedef struct acpi_rsdp
+{
+    char signature[8];
+    uint8_t checksum;
+    char oem_id[6];
+    uint8_t revision;
+    uint32_t rsdt_address;
+} __attribute__((packed)) acpi_rsdp_t;
+
+typedef struct acpi_xsdp
+{
+    char signature[8];
+    uint8_t checksum;
+    char oem_id[6];
+    uint8_t revision;
+    uint32_t rsdt_address;
+    uint32_t resv;
+    uint32_t length;
+    uint64_t xsdt_address;
+    uint8_t extended_checksum;
+    uint8_t reserved[3];
+} __attribute__((packed)) acpi_xsdp_t;
+
+typedef struct acpi_sdt_header
+{
+    char signature[4];
+    uint32_t length;
+    uint8_t revision;
+    uint8_t checksum;
+    char oem_id[6];
+    char oem_table_id[8];
+    uint32_t oem_revision;
+    uint32_t creator_id;
+    uint32_t creator_revision;
+} __attribute__((packed)) acpi_sdt_header_t;
+
+typedef struct acpi_rsdt
+{
+    acpi_sdt_header_t sdt;
+    char table[];
+} __attribute__((packed)) acpi_rsdt_t;
+
+typedef struct acpi_xsdt
+{
+    acpi_sdt_header_t sdt;
+    char table[];
+} __attribute__((packed)) acpi_xsdt_t;
+
+void *acpi_find_table(const char *name);
+void acpi_init(void);
+
+#endif // ACPI_H