1 files changed, 114 insertions, 0 deletions
diff --git a/sys/firmware/acpi/acpi_init.c b/sys/firmware/acpi/acpi_init.c
new file mode 100644
index 0000000..fd23ada
--- /dev/null
+++ b/sys/firmware/acpi/acpi_init.c
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2023 Ian Marco Moffett and the VegaOS team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of VegaOS nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* $Id$ */
+
+#include <firmware/acpi/acpi.h>
+#include <firmware/acpi/tables.h>
+#include <sys/limine.h>
+#include <sys/syslog.h>
+#include <sys/cdefs.h>
+#include <sys/panic.h>
+#include <sys/syslog.h>
+#include <vm/vm.h>
+
+__MODULE_NAME("acpi");
+__KERNEL_META("$Vega$: acpi_init.c, Ian Macro Moffett, "
+              "ACPI init logic");
+
+static volatile struct limine_rsdp_request rsdp_req = {
+    .id = LIMINE_RSDP_REQUEST,
+    .revision = 0
+};
+
+static size_t root_sdt_entries = 0;
+static bool using_xsdt = false;
+static struct acpi_root_sdt *root_sdt = NULL;
+
+/*
+ * Writes out OEMID of ACPI header.
+ *
+ * @type: Type of structure (e.g RSDP)
+ * @hdr: Header of structure.
+ */
+static void
+acpi_print_oemid(const char *type, char oemid[OEMID_SIZE])
+{
+    if (type != NULL) {
+        KINFO("%s OEMID: ", type);
+    }
+
+    for (size_t i = 0; i < OEMID_SIZE; ++i) {
+        kprintf("%c", oemid[i]);
+    }
+    kprintf("\n");
+}
+
+static bool
+acpi_is_checksum_valid(struct acpi_header *hdr)
+{
+    uint8_t sum;
+
+    sum = 0;
+    for (int i = 0; i < hdr->length; ++i) {
+        sum += ((char *)hdr)[i];
+    }
+
+    /* Sum of table (from header to end) must be zero!! */
+    return sum == 0;
+}
+
+void
+acpi_init(void)
+{
+    struct acpi_rsdp *rsdp;
+
+    /* Can't do anything if we have no response! */
+    if (rsdp_req.response == NULL) {
+        panic("RSDP request has no response affiliated...\n");
+    }
+
+    /* Fetch the RSDP */
+    rsdp = rsdp_req.response->address;
+    acpi_print_oemid("RSDP", rsdp->oemid);
+
+    /* Fetch the RSDT/XSDT  */
+    if (rsdp->revision >= 2) {
+        using_xsdt = true;
+        root_sdt = PHYS_TO_VIRT(rsdp->xsdt_addr);
+        KINFO("Using XSDT as root SDT\n");
+    } else {
+        root_sdt = PHYS_TO_VIRT(rsdp->rsdt_addr);
+        KINFO("Using RSDT as root SDT\n");
+    }
+    if (!acpi_is_checksum_valid(&root_sdt->hdr)) {
+        panic("Root SDT has an invalid checksum!\n");
+    }
+    root_sdt_entries = (root_sdt->hdr.length - sizeof(root_sdt->hdr)) / 4;
+}