1 files changed, 82 insertions, 0 deletions
diff --git a/sys/dev/acpi/acpi_subr.c b/sys/dev/acpi/acpi_subr.c
new file mode 100644
index 0000000..7cf3287
--- /dev/null
+++ b/sys/dev/acpi/acpi_subr.c
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora 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 Hyra 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.
+ */
+
+#include <sys/types.h>
+#include <dev/acpi/acpi.h>
+#include <dev/acpi/acpivar.h>
+#include <dev/acpi/tables.h>
+#include <vm/vm.h>
+#include <string.h>
+
+/*
+ * Compute the ACPI checksum of a header.
+ *
+ * @hdr: HDR to check.
+ *
+ * Must return zero to be a valid checksum!
+ */
+uint8_t
+acpi_checksum(struct acpi_header *hdr)
+{
+    uint8_t sum = 0;
+
+    for (int i = 0; i < hdr->length; ++i) {
+        sum += ((char *)hdr)[i];
+    }
+
+    return sum;
+}
+
+/*
+ * Looks up an ACPI table with a specific
+ * signature e.g "APIC" for MADT (if present).
+ *
+ * @query: The specific query to make e.g "APIC"
+ */
+void *
+acpi_query(const char *query)
+{
+    struct acpi_header *hdr;
+    struct acpi_root_sdt *root_sdt;
+    size_t root_sdt_len, signature_len;
+
+    root_sdt = acpi_get_root_sdt();
+    root_sdt_len = acpi_get_root_sdt_len();
+    signature_len = sizeof(hdr->signature);
+
+    for (size_t i = 0; i < root_sdt_len; ++i) {
+        hdr = (struct acpi_header *)PHYS_TO_VIRT(root_sdt->tables[i]);
+
+        if (memcmp(hdr->signature, query, signature_len) == 0) {
+            return (void *)hdr;
+        }
+    }
+
+    return NULL;
+}