x86/efi/bgrt: Move efi-bgrt handling out of arch/x86

Now with open-source boot firmware (EDK2) supporting ACPI BGRT table
addition even for architectures like AARCH64, it makes sense to move
out the 'efi-bgrt.c' file and supporting infrastructure from 'arch/x86'
directory and house it inside 'drivers/firmware/efi', so that this common
code can be used across architectures.

Signed-off-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170404160245.27812-7-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 85 insertions, 0 deletions

diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index ad67342313ed..0329d319d89a 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -9,6 +9,7 @@
 #
 KASAN_SANITIZE_runtime-wrappers.o	:= n
 
+obj-$(CONFIG_ACPI_BGRT) 		+= efi-bgrt.o
 obj-$(CONFIG_EFI)			+= efi.o vars.o reboot.o memattr.o
 obj-$(CONFIG_EFI)			+= capsule.o memmap.o
 obj-$(CONFIG_EFI_VARS)			+= efivars.o
diff --git a/drivers/firmware/efi/efi-bgrt.c b/drivers/firmware/efi/efi-bgrt.c
new file mode 100644
index 000000000000..04ca8764f0c0
--- /dev/null
+++ b/drivers/firmware/efi/efi-bgrt.c
@@ -0,0 +1,84 @@
+/*
+ * 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
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#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 __initdata 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 (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;
+	if (bgrt->version != 1) {
+		pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
+		       bgrt->version);
+		goto out;
+	}
+	if (bgrt->status & 0xfe) {
+		pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n",
+		       bgrt->status);
+		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;
+	}
+
+	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));
+}