drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c - kernel/bruno - Git at Google

 /*
  * Copyright 2008 Advanced Micro Devices, Inc.
  * Copyright 2008 Red Hat Inc.
  * Copyright 2009 Jerome Glisse.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  * Authors: Dave Airlie
  *          Alex Deucher
  *          Jerome Glisse
  */
 #include <drm/drmP.h>
 #include "amdgpu.h"
 #include "atom.h"

 #include <linux/slab.h>
 #include <linux/acpi.h>
 /*
  * BIOS.
  */

 /* If you boot an IGP board with a discrete card as the primary,
  * the IGP rom is not accessible via the rom bar as the IGP rom is
  * part of the system bios.  On boot, the system bios puts a
  * copy of the igp rom at the start of vram if a discrete card is
  * present.
  */
 static bool igp_read_bios_from_vram(struct amdgpu_device *adev)
 {
 	uint8_t __iomem *bios;
 	resource_size_t vram_base;
 	resource_size_t size = 256 * 1024; /* ??? */

 	if (!(adev->flags & AMD_IS_APU))
 		if (!amdgpu_card_posted(adev))
 			return false;

 	adev->bios = NULL;
 	vram_base = pci_resource_start(adev->pdev, 0);
 	bios = ioremap(vram_base, size);
 	if (!bios) {
 		return false;
 	}

 	if (size == 0 || bios[0] != 0x55 || bios[1] != 0xaa) {
 		iounmap(bios);
 		return false;
 	}
 	adev->bios = kmalloc(size, GFP_KERNEL);
 	if (adev->bios == NULL) {
 		iounmap(bios);
 		return false;
 	}
 	memcpy_fromio(adev->bios, bios, size);
 	iounmap(bios);
 	return true;
 }

 bool amdgpu_read_bios(struct amdgpu_device *adev)
 {
 	uint8_t __iomem *bios, val1, val2;
 	size_t size;

 	adev->bios = NULL;
 	/* XXX: some cards may return 0 for rom size? ddx has a workaround */
 	bios = pci_map_rom(adev->pdev, &size);
 	if (!bios) {
 		return false;
 	}

 	val1 = readb(&bios[0]);
 	val2 = readb(&bios[1]);

 	if (size == 0 || val1 != 0x55 || val2 != 0xaa) {
 		pci_unmap_rom(adev->pdev, bios);
 		return false;
 	}
 	adev->bios = kzalloc(size, GFP_KERNEL);
 	if (adev->bios == NULL) {
 		pci_unmap_rom(adev->pdev, bios);
 		return false;
 	}
 	memcpy_fromio(adev->bios, bios, size);
 	pci_unmap_rom(adev->pdev, bios);
 	return true;
 }

 static bool amdgpu_read_platform_bios(struct amdgpu_device *adev)
 {
 	uint8_t __iomem *bios;
 	size_t size;

 	adev->bios = NULL;

 	bios = pci_platform_rom(adev->pdev, &size);
 	if (!bios) {
 		return false;
 	}

 	if (size == 0 || bios[0] != 0x55 || bios[1] != 0xaa) {
 		return false;
 	}
 	adev->bios = kmemdup(bios, size, GFP_KERNEL);
 	if (adev->bios == NULL) {
 		return false;
 	}

 	return true;
 }

 #ifdef CONFIG_ACPI
 /* ATRM is used to get the BIOS on the discrete cards in
  * dual-gpu systems.
  */
 /* retrieve the ROM in 4k blocks */
 #define ATRM_BIOS_PAGE 4096
 /**
  * amdgpu_atrm_call - fetch a chunk of the vbios
  *
  * @atrm_handle: acpi ATRM handle
  * @bios: vbios image pointer
  * @offset: offset of vbios image data to fetch
  * @len: length of vbios image data to fetch
  *
  * Executes ATRM to fetch a chunk of the discrete
  * vbios image on PX systems (all asics).
  * Returns the length of the buffer fetched.
  */
 static int amdgpu_atrm_call(acpi_handle atrm_handle, uint8_t *bios,
 			    int offset, int len)
 {
 	acpi_status status;
 	union acpi_object atrm_arg_elements[2], *obj;
 	struct acpi_object_list atrm_arg;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL};

 	atrm_arg.count = 2;
 	atrm_arg.pointer = &atrm_arg_elements[0];

 	atrm_arg_elements[0].type = ACPI_TYPE_INTEGER;
 	atrm_arg_elements[0].integer.value = offset;

 	atrm_arg_elements[1].type = ACPI_TYPE_INTEGER;
 	atrm_arg_elements[1].integer.value = len;

 	status = acpi_evaluate_object(atrm_handle, NULL, &atrm_arg, &buffer);
 	if (ACPI_FAILURE(status)) {
 		printk("failed to evaluate ATRM got %s\n", acpi_format_exception(status));
 		return -ENODEV;
 	}

 	obj = (union acpi_object *)buffer.pointer;
 	memcpy(bios+offset, obj->buffer.pointer, obj->buffer.length);
 	len = obj->buffer.length;
 	kfree(buffer.pointer);
 	return len;
 }

 static bool amdgpu_atrm_get_bios(struct amdgpu_device *adev)
 {
 	int ret;
 	int size = 256 * 1024;
 	int i;
 	struct pci_dev *pdev = NULL;
 	acpi_handle dhandle, atrm_handle;
 	acpi_status status;
 	bool found = false;

 	/* ATRM is for the discrete card only */
 	if (adev->flags & AMD_IS_APU)
 		return false;

 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
 		dhandle = ACPI_HANDLE(&pdev->dev);
 		if (!dhandle)
 			continue;

 		status = acpi_get_handle(dhandle, "ATRM", &atrm_handle);
 		if (!ACPI_FAILURE(status)) {
 			found = true;
 			break;
 		}
 	}

 	if (!found) {
 		while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_OTHER << 8, pdev)) != NULL) {
 			dhandle = ACPI_HANDLE(&pdev->dev);
 			if (!dhandle)
 				continue;

 			status = acpi_get_handle(dhandle, "ATRM", &atrm_handle);
 			if (!ACPI_FAILURE(status)) {
 				found = true;
 				break;
 			}
 		}
 	}

 	if (!found)
 		return false;

 	adev->bios = kmalloc(size, GFP_KERNEL);
 	if (!adev->bios) {
 		DRM_ERROR("Unable to allocate bios\n");
 		return false;
 	}

 	for (i = 0; i < size / ATRM_BIOS_PAGE; i++) {
 		ret = amdgpu_atrm_call(atrm_handle,
 				       adev->bios,
 				       (i * ATRM_BIOS_PAGE),
 				       ATRM_BIOS_PAGE);
 		if (ret < ATRM_BIOS_PAGE)
 			break;
 	}

 	if (i == 0 || adev->bios[0] != 0x55 || adev->bios[1] != 0xaa) {
 		kfree(adev->bios);
 		return false;
 	}
 	return true;
 }
 #else
 static inline bool amdgpu_atrm_get_bios(struct amdgpu_device *adev)
 {
 	return false;
 }
 #endif

 static bool amdgpu_read_disabled_bios(struct amdgpu_device *adev)
 {
 	if (adev->flags & AMD_IS_APU)
 		return igp_read_bios_from_vram(adev);
 	else
 		return amdgpu_asic_read_disabled_bios(adev);
 }

 #ifdef CONFIG_ACPI
 static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
 {
 	bool ret = false;
 	struct acpi_table_header *hdr;
 	acpi_size tbl_size;
 	UEFI_ACPI_VFCT *vfct;
 	GOP_VBIOS_CONTENT *vbios;
 	VFCT_IMAGE_HEADER *vhdr;

 	if (!ACPI_SUCCESS(acpi_get_table_with_size("VFCT", 1, &hdr, &tbl_size)))
 		return false;
 	if (tbl_size < sizeof(UEFI_ACPI_VFCT)) {
 		DRM_ERROR("ACPI VFCT table present but broken (too short #1)\n");
 		goto out_unmap;
 	}

 	vfct = (UEFI_ACPI_VFCT *)hdr;
 	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) > tbl_size) {
 		DRM_ERROR("ACPI VFCT table present but broken (too short #2)\n");
 		goto out_unmap;
 	}

 	vbios = (GOP_VBIOS_CONTENT *)((char *)hdr + vfct->VBIOSImageOffset);
 	vhdr = &vbios->VbiosHeader;
 	DRM_INFO("ACPI VFCT contains a BIOS for %02x:%02x.%d %04x:%04x, size %d\n",
 			vhdr->PCIBus, vhdr->PCIDevice, vhdr->PCIFunction,
 			vhdr->VendorID, vhdr->DeviceID, vhdr->ImageLength);

 	if (vhdr->PCIBus != adev->pdev->bus->number ||
 	    vhdr->PCIDevice != PCI_SLOT(adev->pdev->devfn) ||
 	    vhdr->PCIFunction != PCI_FUNC(adev->pdev->devfn) ||
 	    vhdr->VendorID != adev->pdev->vendor ||
 	    vhdr->DeviceID != adev->pdev->device) {
 		DRM_INFO("ACPI VFCT table is not for this card\n");
 		goto out_unmap;
 	}

 	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) + vhdr->ImageLength > tbl_size) {
 		DRM_ERROR("ACPI VFCT image truncated\n");
 		goto out_unmap;
 	}

 	adev->bios = kmemdup(&vbios->VbiosContent, vhdr->ImageLength, GFP_KERNEL);
 	ret = !!adev->bios;

 out_unmap:
 	return ret;
 }
 #else
 static inline bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
 {
 	return false;
 }
 #endif

 bool amdgpu_get_bios(struct amdgpu_device *adev)
 {
 	bool r;
 	uint16_t tmp;

 	r = amdgpu_atrm_get_bios(adev);
 	if (r == false)
 		r = amdgpu_acpi_vfct_bios(adev);
 	if (r == false)
 		r = igp_read_bios_from_vram(adev);
 	if (r == false)
 		r = amdgpu_read_bios(adev);
 	if (r == false) {
 		r = amdgpu_read_disabled_bios(adev);
 	}
 	if (r == false) {
 		r = amdgpu_read_platform_bios(adev);
 	}
 	if (r == false || adev->bios == NULL) {
 		DRM_ERROR("Unable to locate a BIOS ROM\n");
 		adev->bios = NULL;
 		return false;
 	}
 	if (adev->bios[0] != 0x55 || adev->bios[1] != 0xaa) {
 		printk("BIOS signature incorrect %x %x\n", adev->bios[0], adev->bios[1]);
 		goto free_bios;
 	}

 	tmp = RBIOS16(0x18);
 	if (RBIOS8(tmp + 0x14) != 0x0) {
 		DRM_INFO("Not an x86 BIOS ROM, not using.\n");
 		goto free_bios;
 	}

 	adev->bios_header_start = RBIOS16(0x48);
 	if (!adev->bios_header_start) {
 		goto free_bios;
 	}
 	tmp = adev->bios_header_start + 4;
 	if (!memcmp(adev->bios + tmp, "ATOM", 4) ||
 	    !memcmp(adev->bios + tmp, "MOTA", 4)) {
 		adev->is_atom_bios = true;
 	} else {
 		adev->is_atom_bios = false;
 	}

 	DRM_DEBUG("%sBIOS detected\n", adev->is_atom_bios ? "ATOM" : "COM");
 	return true;
 free_bios:
 	kfree(adev->bios);
 	adev->bios = NULL;
 	return false;
 }
	/*
	* Copyright 2008 Advanced Micro Devices, Inc.
	* Copyright 2008 Red Hat Inc.
	* Copyright 2009 Jerome Glisse.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*
	* Authors: Dave Airlie
	* Alex Deucher
	* Jerome Glisse
	*/
	#include <drm/drmP.h>
	#include "amdgpu.h"
	#include "atom.h"

	#include <linux/slab.h>
	#include <linux/acpi.h>
	/*
	* BIOS.
	*/

	/* If you boot an IGP board with a discrete card as the primary,
	* the IGP rom is not accessible via the rom bar as the IGP rom is
	* part of the system bios. On boot, the system bios puts a
	* copy of the igp rom at the start of vram if a discrete card is
	* present.
	*/
	static bool igp_read_bios_from_vram(struct amdgpu_device *adev)
	{
	uint8_t __iomem *bios;
	resource_size_t vram_base;
	resource_size_t size = 256 * 1024; /* ??? */

	if (!(adev->flags & AMD_IS_APU))
	if (!amdgpu_card_posted(adev))
	return false;

	adev->bios = NULL;
	vram_base = pci_resource_start(adev->pdev, 0);
	bios = ioremap(vram_base, size);
	if (!bios) {
	return false;
	}

	if (size == 0 \|\| bios[0] != 0x55 \|\| bios[1] != 0xaa) {
	iounmap(bios);
	return false;
	}
	adev->bios = kmalloc(size, GFP_KERNEL);
	if (adev->bios == NULL) {
	iounmap(bios);
	return false;
	}
	memcpy_fromio(adev->bios, bios, size);
	iounmap(bios);
	return true;
	}

	bool amdgpu_read_bios(struct amdgpu_device *adev)
	{
	uint8_t __iomem *bios, val1, val2;
	size_t size;

	adev->bios = NULL;
	/* XXX: some cards may return 0 for rom size? ddx has a workaround */
	bios = pci_map_rom(adev->pdev, &size);
	if (!bios) {
	return false;
	}

	val1 = readb(&bios[0]);
	val2 = readb(&bios[1]);

	if (size == 0 \|\| val1 != 0x55 \|\| val2 != 0xaa) {
	pci_unmap_rom(adev->pdev, bios);
	return false;
	}
	adev->bios = kzalloc(size, GFP_KERNEL);
	if (adev->bios == NULL) {
	pci_unmap_rom(adev->pdev, bios);
	return false;
	}
	memcpy_fromio(adev->bios, bios, size);
	pci_unmap_rom(adev->pdev, bios);
	return true;
	}

	static bool amdgpu_read_platform_bios(struct amdgpu_device *adev)
	{
	uint8_t __iomem *bios;
	size_t size;

	adev->bios = NULL;

	bios = pci_platform_rom(adev->pdev, &size);
	if (!bios) {
	return false;
	}

	if (size == 0 \|\| bios[0] != 0x55 \|\| bios[1] != 0xaa) {
	return false;
	}
	adev->bios = kmemdup(bios, size, GFP_KERNEL);
	if (adev->bios == NULL) {
	return false;
	}

	return true;
	}

	#ifdef CONFIG_ACPI
	/* ATRM is used to get the BIOS on the discrete cards in
	* dual-gpu systems.
	*/
	/* retrieve the ROM in 4k blocks */
	#define ATRM_BIOS_PAGE 4096
	/**
	* amdgpu_atrm_call - fetch a chunk of the vbios
	*
	* @atrm_handle: acpi ATRM handle
	* @bios: vbios image pointer
	* @offset: offset of vbios image data to fetch
	* @len: length of vbios image data to fetch
	*
	* Executes ATRM to fetch a chunk of the discrete
	* vbios image on PX systems (all asics).
	* Returns the length of the buffer fetched.
	*/
	static int amdgpu_atrm_call(acpi_handle atrm_handle, uint8_t *bios,
	int offset, int len)
	{
	acpi_status status;
	union acpi_object atrm_arg_elements[2], *obj;
	struct acpi_object_list atrm_arg;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL};

	atrm_arg.count = 2;
	atrm_arg.pointer = &atrm_arg_elements[0];

	atrm_arg_elements[0].type = ACPI_TYPE_INTEGER;
	atrm_arg_elements[0].integer.value = offset;

	atrm_arg_elements[1].type = ACPI_TYPE_INTEGER;
	atrm_arg_elements[1].integer.value = len;

	status = acpi_evaluate_object(atrm_handle, NULL, &atrm_arg, &buffer);
	if (ACPI_FAILURE(status)) {
	printk("failed to evaluate ATRM got %s\n", acpi_format_exception(status));
	return -ENODEV;
	}

	obj = (union acpi_object *)buffer.pointer;
	memcpy(bios+offset, obj->buffer.pointer, obj->buffer.length);
	len = obj->buffer.length;
	kfree(buffer.pointer);
	return len;
	}

	static bool amdgpu_atrm_get_bios(struct amdgpu_device *adev)
	{
	int ret;
	int size = 256 * 1024;
	int i;
	struct pci_dev *pdev = NULL;
	acpi_handle dhandle, atrm_handle;
	acpi_status status;
	bool found = false;

	/* ATRM is for the discrete card only */
	if (adev->flags & AMD_IS_APU)
	return false;

	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
	dhandle = ACPI_HANDLE(&pdev->dev);
	if (!dhandle)
	continue;

	status = acpi_get_handle(dhandle, "ATRM", &atrm_handle);
	if (!ACPI_FAILURE(status)) {
	found = true;
	break;
	}
	}

	if (!found) {
	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_OTHER << 8, pdev)) != NULL) {
	dhandle = ACPI_HANDLE(&pdev->dev);
	if (!dhandle)
	continue;

	status = acpi_get_handle(dhandle, "ATRM", &atrm_handle);
	if (!ACPI_FAILURE(status)) {
	found = true;
	break;
	}
	}
	}

	if (!found)
	return false;

	adev->bios = kmalloc(size, GFP_KERNEL);
	if (!adev->bios) {
	DRM_ERROR("Unable to allocate bios\n");
	return false;
	}

	for (i = 0; i < size / ATRM_BIOS_PAGE; i++) {
	ret = amdgpu_atrm_call(atrm_handle,
	adev->bios,
	(i * ATRM_BIOS_PAGE),
	ATRM_BIOS_PAGE);
	if (ret < ATRM_BIOS_PAGE)
	break;
	}

	if (i == 0 \|\| adev->bios[0] != 0x55 \|\| adev->bios[1] != 0xaa) {
	kfree(adev->bios);
	return false;
	}
	return true;
	}
	#else
	static inline bool amdgpu_atrm_get_bios(struct amdgpu_device *adev)
	{
	return false;
	}
	#endif

	static bool amdgpu_read_disabled_bios(struct amdgpu_device *adev)
	{
	if (adev->flags & AMD_IS_APU)
	return igp_read_bios_from_vram(adev);
	else
	return amdgpu_asic_read_disabled_bios(adev);
	}

	#ifdef CONFIG_ACPI
	static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
	{
	bool ret = false;
	struct acpi_table_header *hdr;
	acpi_size tbl_size;
	UEFI_ACPI_VFCT *vfct;
	GOP_VBIOS_CONTENT *vbios;
	VFCT_IMAGE_HEADER *vhdr;

	if (!ACPI_SUCCESS(acpi_get_table_with_size("VFCT", 1, &hdr, &tbl_size)))
	return false;
	if (tbl_size < sizeof(UEFI_ACPI_VFCT)) {
	DRM_ERROR("ACPI VFCT table present but broken (too short #1)\n");
	goto out_unmap;
	}

	vfct = (UEFI_ACPI_VFCT *)hdr;
	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) > tbl_size) {
	DRM_ERROR("ACPI VFCT table present but broken (too short #2)\n");
	goto out_unmap;
	}

	vbios = (GOP_VBIOS_CONTENT )((char )hdr + vfct->VBIOSImageOffset);
	vhdr = &vbios->VbiosHeader;
	DRM_INFO("ACPI VFCT contains a BIOS for %02x:%02x.%d %04x:%04x, size %d\n",
	vhdr->PCIBus, vhdr->PCIDevice, vhdr->PCIFunction,
	vhdr->VendorID, vhdr->DeviceID, vhdr->ImageLength);

	if (vhdr->PCIBus != adev->pdev->bus->number \|\|
	vhdr->PCIDevice != PCI_SLOT(adev->pdev->devfn) \|\|
	vhdr->PCIFunction != PCI_FUNC(adev->pdev->devfn) \|\|
	vhdr->VendorID != adev->pdev->vendor \|\|
	vhdr->DeviceID != adev->pdev->device) {
	DRM_INFO("ACPI VFCT table is not for this card\n");
	goto out_unmap;
	}

	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) + vhdr->ImageLength > tbl_size) {
	DRM_ERROR("ACPI VFCT image truncated\n");
	goto out_unmap;
	}

	adev->bios = kmemdup(&vbios->VbiosContent, vhdr->ImageLength, GFP_KERNEL);
	ret = !!adev->bios;

	out_unmap:
	return ret;
	}
	#else
	static inline bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
	{
	return false;
	}
	#endif

	bool amdgpu_get_bios(struct amdgpu_device *adev)
	{
	bool r;
	uint16_t tmp;

	r = amdgpu_atrm_get_bios(adev);
	if (r == false)
	r = amdgpu_acpi_vfct_bios(adev);
	if (r == false)
	r = igp_read_bios_from_vram(adev);
	if (r == false)
	r = amdgpu_read_bios(adev);
	if (r == false) {
	r = amdgpu_read_disabled_bios(adev);
	}
	if (r == false) {
	r = amdgpu_read_platform_bios(adev);
	}
	if (r == false \|\| adev->bios == NULL) {
	DRM_ERROR("Unable to locate a BIOS ROM\n");
	adev->bios = NULL;
	return false;
	}
	if (adev->bios[0] != 0x55 \|\| adev->bios[1] != 0xaa) {
	printk("BIOS signature incorrect %x %x\n", adev->bios[0], adev->bios[1]);
	goto free_bios;
	}

	tmp = RBIOS16(0x18);
	if (RBIOS8(tmp + 0x14) != 0x0) {
	DRM_INFO("Not an x86 BIOS ROM, not using.\n");
	goto free_bios;
	}

	adev->bios_header_start = RBIOS16(0x48);
	if (!adev->bios_header_start) {
	goto free_bios;
	}
	tmp = adev->bios_header_start + 4;
	if (!memcmp(adev->bios + tmp, "ATOM", 4) \|\|
	!memcmp(adev->bios + tmp, "MOTA", 4)) {
	adev->is_atom_bios = true;
	} else {
	adev->is_atom_bios = false;
	}

	DRM_DEBUG("%sBIOS detected\n", adev->is_atom_bios ? "ATOM" : "COM");
	return true;
	free_bios:
	kfree(adev->bios);
	adev->bios = NULL;
	return false;
	}