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path: root/drivers/firmware/efi/efi-bgrt.c
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Diffstat (limited to 'drivers/firmware/efi/efi-bgrt.c')
-rw-r--r--drivers/firmware/efi/efi-bgrt.c88
1 files changed, 88 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi-bgrt.c b/drivers/firmware/efi/efi-bgrt.c
new file mode 100644
index 0000000000..6aafdb67db
--- /dev/null
+++ b/drivers/firmware/efi/efi-bgrt.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2012 Intel Corporation
+ * Author: Josh Triplett <josh@joshtriplett.org>
+ *
+ * Based on the bgrt driver:
+ * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
+ * Author: Matthew Garrett
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/acpi.h>
+#include <linux/efi.h>
+#include <linux/efi-bgrt.h>
+
+struct acpi_table_bgrt bgrt_tab;
+size_t bgrt_image_size;
+
+struct bmp_header {
+ u16 id;
+ u32 size;
+} __packed;
+
+void __init efi_bgrt_init(struct acpi_table_header *table)
+{
+ void *image;
+ struct bmp_header bmp_header;
+ struct acpi_table_bgrt *bgrt = &bgrt_tab;
+
+ if (acpi_disabled)
+ return;
+
+ if (!efi_enabled(EFI_MEMMAP))
+ return;
+
+ if (table->length < sizeof(bgrt_tab)) {
+ pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
+ table->length, sizeof(bgrt_tab));
+ return;
+ }
+ *bgrt = *(struct acpi_table_bgrt *)table;
+ /*
+ * Only version 1 is defined but some older laptops (seen on Lenovo
+ * Ivy Bridge models) have a correct version 1 BGRT table with the
+ * version set to 0, so we accept version 0 and 1.
+ */
+ if (bgrt->version > 1) {
+ pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
+ bgrt->version);
+ goto out;
+ }
+ if (bgrt->image_type != 0) {
+ pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
+ bgrt->image_type);
+ goto out;
+ }
+ if (!bgrt->image_address) {
+ pr_notice("Ignoring BGRT: null image address\n");
+ goto out;
+ }
+
+ if (efi_mem_type(bgrt->image_address) != EFI_BOOT_SERVICES_DATA) {
+ pr_notice("Ignoring BGRT: invalid image address\n");
+ goto out;
+ }
+ image = early_memremap(bgrt->image_address, sizeof(bmp_header));
+ if (!image) {
+ pr_notice("Ignoring BGRT: failed to map image header memory\n");
+ goto out;
+ }
+
+ memcpy(&bmp_header, image, sizeof(bmp_header));
+ early_memunmap(image, sizeof(bmp_header));
+ if (bmp_header.id != 0x4d42) {
+ pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
+ bmp_header.id);
+ goto out;
+ }
+ bgrt_image_size = bmp_header.size;
+ efi_mem_reserve(bgrt->image_address, bgrt_image_size);
+
+ return;
+out:
+ memset(bgrt, 0, sizeof(bgrt_tab));
+}