feat/kernel: Started on basic bootstrap ACPI

kernel/src/sys/acpi.c

@@ -0,0 +1,122 @@
+/* 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>
+
+static int acpi_uses_xsdt = 0;
+static void *acpi_rsdt_ptr = NULL;
+
+static uint8_t acpi_checksum(void *ptr, size_t len)
+{
+    uint8_t sum = 0;
+    uint8_t *data = (uint8_t *)ptr;
+    for (size_t i = 0; i < len; i++)
+    {
+        sum += data[i];
+    }
+    return sum;
+}
+
+static int acpi_validate_rsdp(acpi_rsdp_t *rsdp)
+{
+    return acpi_checksum(rsdp, sizeof(acpi_rsdp_t)) == 0;
+}
+
+static int acpi_validate_xsdp(acpi_xsdp_t *xsdp)
+{
+    if (acpi_checksum(xsdp, sizeof(acpi_rsdp_t)) != 0)
+        return 0;
+    if (acpi_checksum(xsdp, xsdp->length) != 0)
+        return 0;
+    return 1;
+}
+
+void acpi_init(void)
+{
+    if (!rsdp_response || !rsdp_response->address)
+    {
+        kpanic(NULL, "No RSDP provided");
+    }
+
+    acpi_rsdp_t *rsdp = (acpi_rsdp_t *)rsdp_response->address;
+    log_early("RSDP found at %p", rsdp);
+    if (strncmp(rsdp->signature, "RSD PTR ", 8) != 0)
+    {
+        kpanic(NULL, "Invalid RSDP signature");
+    }
+
+    if (rsdp->revision >= 2)
+    {
+        acpi_xsdp_t *xsdp = (acpi_xsdp_t *)rsdp;
+        if (!acpi_validate_xsdp(xsdp))
+        {
+            kpanic(NULL, "XSDP checksum validation failed");
+        }
+        acpi_uses_xsdt = 1;
+        acpi_rsdt_ptr = (void *)(uintptr_t)xsdp->xsdt_address;
+    }
+    else
+    {
+        if (!acpi_validate_rsdp(rsdp))
+        {
+            kpanic(NULL, "RSDP checksum validation failed");
+        }
+        acpi_uses_xsdt = 0;
+        acpi_rsdt_ptr = (void *)(uintptr_t)rsdp->rsdt_address;
+    }
+
+    /* Validate RSDT/XSDT header */
+    acpi_sdt_header_t *sdt = (acpi_sdt_header_t *)acpi_rsdt_ptr;
+    if (acpi_checksum(sdt, sdt->length) != 0)
+    {
+        kpanic(NULL, "RSDT/XSDT checksum validation failed");
+    }
+
+    log_early("ACPI initialized, using %s at %p",
+              acpi_uses_xsdt ? "XSDT" : "RSDT", acpi_rsdt_ptr);
+}
+
+void *acpi_find_table(const char *name)
+{
+    if (!acpi_rsdt_ptr || !name)
+        return NULL;
+
+    acpi_sdt_header_t *sdt = (acpi_sdt_header_t *)acpi_rsdt_ptr;
+    uint32_t entries;
+
+    if (acpi_uses_xsdt)
+    {
+        entries = (sdt->length - sizeof(acpi_sdt_header_t)) / sizeof(uint64_t);
+    }
+    else
+    {
+        entries = (sdt->length - sizeof(acpi_sdt_header_t)) / sizeof(uint32_t);
+    }
+
+    for (uint32_t i = 0; i < entries; i++)
+    {
+        acpi_sdt_header_t *table;
+        if (acpi_uses_xsdt)
+        {
+            uint64_t *xsdt_entries = (uint64_t *)(sdt + 1);
+            table = (acpi_sdt_header_t *)(uintptr_t)xsdt_entries[i];
+        }
+        else
+        {
+            uint32_t *rsdt_entries = (uint32_t *)(sdt + 1);
+            table = (acpi_sdt_header_t *)(uintptr_t)rsdt_entries[i];
+        }
+
+        if (strncmp(table->signature, name, 4) == 0)
+        {
+            if (acpi_checksum(table, table->length) == 0)
+            {
+                return table;
+            }
+        }
+    }
+
+    return NULL;
+}