drivers/gpu/drm/nouveau/nouveau_acpi.c - linux-mtk - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include <linux/pci.h>
 #include <linux/acpi.h>
 #include <linux/slab.h>
 #include <linux/mxm-wmi.h>
 #include <linux/vga_switcheroo.h>
 #include <drm/drm_edid.h>
 #include <acpi/video.h>

 #include "nouveau_drv.h"
 #include "nouveau_acpi.h"

 #define NOUVEAU_DSM_LED 0x02
 #define NOUVEAU_DSM_LED_STATE 0x00
 #define NOUVEAU_DSM_LED_OFF 0x10
 #define NOUVEAU_DSM_LED_STAMINA 0x11
 #define NOUVEAU_DSM_LED_SPEED 0x12

 #define NOUVEAU_DSM_POWER 0x03
 #define NOUVEAU_DSM_POWER_STATE 0x00
 #define NOUVEAU_DSM_POWER_SPEED 0x01
 #define NOUVEAU_DSM_POWER_STAMINA 0x02

 #define NOUVEAU_DSM_OPTIMUS_CAPS 0x1A
 #define NOUVEAU_DSM_OPTIMUS_FLAGS 0x1B

 #define NOUVEAU_DSM_OPTIMUS_POWERDOWN_PS3 (3 << 24)
 #define NOUVEAU_DSM_OPTIMUS_NO_POWERDOWN_PS3 (2 << 24)
 #define NOUVEAU_DSM_OPTIMUS_FLAGS_CHANGED (1)

 #define NOUVEAU_DSM_OPTIMUS_SET_POWERDOWN (NOUVEAU_DSM_OPTIMUS_POWERDOWN_PS3 | NOUVEAU_DSM_OPTIMUS_FLAGS_CHANGED)

 /* result of the optimus caps function */
 #define OPTIMUS_ENABLED (1 << 0)
 #define OPTIMUS_STATUS_MASK (3 << 3)
 #define OPTIMUS_STATUS_OFF  (0 << 3)
 #define OPTIMUS_STATUS_ON_ENABLED  (1 << 3)
 #define OPTIMUS_STATUS_PWR_STABLE  (3 << 3)
 #define OPTIMUS_DISPLAY_HOTPLUG (1 << 6)
 #define OPTIMUS_CAPS_MASK (7 << 24)
 #define OPTIMUS_DYNAMIC_PWR_CAP (1 << 24)

 #define OPTIMUS_AUDIO_CAPS_MASK (3 << 27)
 #define OPTIMUS_HDA_CODEC_MASK (2 << 27) /* hda bios control */

 static struct nouveau_dsm_priv {
 	bool dsm_detected;
 	bool optimus_detected;
 	bool optimus_flags_detected;
 	bool optimus_skip_dsm;
 	acpi_handle dhandle;
 	acpi_handle rom_handle;
 } nouveau_dsm_priv;

 bool nouveau_is_optimus(void) {
 	return nouveau_dsm_priv.optimus_detected;
 }

 bool nouveau_is_v1_dsm(void) {
 	return nouveau_dsm_priv.dsm_detected;
 }

 #ifdef CONFIG_VGA_SWITCHEROO
 static const guid_t nouveau_dsm_muid =
 	GUID_INIT(0x9D95A0A0, 0x0060, 0x4D48,
 		  0xB3, 0x4D, 0x7E, 0x5F, 0xEA, 0x12, 0x9F, 0xD4);

 static const guid_t nouveau_op_dsm_muid =
 	GUID_INIT(0xA486D8F8, 0x0BDA, 0x471B,
 		  0xA7, 0x2B, 0x60, 0x42, 0xA6, 0xB5, 0xBE, 0xE0);

 static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t *result)
 {
 	int i;
 	union acpi_object *obj;
 	char args_buff[4];
 	union acpi_object argv4 = {
 		.buffer.type = ACPI_TYPE_BUFFER,
 		.buffer.length = 4,
 		.buffer.pointer = args_buff
 	};

 	/* ACPI is little endian, AABBCCDD becomes {DD,CC,BB,AA} */
 	for (i = 0; i < 4; i++)
 		args_buff[i] = (arg >> i * 8) & 0xFF;

 	*result = 0;
 	obj = acpi_evaluate_dsm_typed(handle, &nouveau_op_dsm_muid, 0x00000100,
 				      func, &argv4, ACPI_TYPE_BUFFER);
 	if (!obj) {
 		acpi_handle_info(handle, "failed to evaluate _DSM\n");
 		return AE_ERROR;
 	} else {
 		if (obj->buffer.length == 4) {
 			*result |= obj->buffer.pointer[0];
 			*result |= (obj->buffer.pointer[1] << 8);
 			*result |= (obj->buffer.pointer[2] << 16);
 			*result |= (obj->buffer.pointer[3] << 24);
 		}
 		ACPI_FREE(obj);
 	}

 	return 0;
 }

 /*
  * On some platforms, _DSM(nouveau_op_dsm_muid, func0) has special
  * requirements on the fourth parameter, so a private implementation
  * instead of using acpi_check_dsm().
  */
 static int nouveau_dsm_get_optimus_functions(acpi_handle handle)
 {
 	int result;

 	/*
 	 * Function 0 returns a Buffer containing available functions.
 	 * The args parameter is ignored for function 0, so just put 0 in it
 	 */
 	if (nouveau_optimus_dsm(handle, 0, 0, &result))
 		return 0;

 	/*
 	 * ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported.
 	 * If the n-th bit is enabled, function n is supported
 	 */
 	if (result & 1 && result & (1 << NOUVEAU_DSM_OPTIMUS_CAPS))
 		return result;
 	return 0;
 }

 static int nouveau_dsm(acpi_handle handle, int func, int arg)
 {
 	int ret = 0;
 	union acpi_object *obj;
 	union acpi_object argv4 = {
 		.integer.type = ACPI_TYPE_INTEGER,
 		.integer.value = arg,
 	};

 	obj = acpi_evaluate_dsm_typed(handle, &nouveau_dsm_muid, 0x00000102,
 				      func, &argv4, ACPI_TYPE_INTEGER);
 	if (!obj) {
 		acpi_handle_info(handle, "failed to evaluate _DSM\n");
 		return AE_ERROR;
 	} else {
 		if (obj->integer.value == 0x80000002)
 			ret = -ENODEV;
 		ACPI_FREE(obj);
 	}

 	return ret;
 }

 static int nouveau_dsm_switch_mux(acpi_handle handle, int mux_id)
 {
 	mxm_wmi_call_mxmx(mux_id == NOUVEAU_DSM_LED_STAMINA ? MXM_MXDS_ADAPTER_IGD : MXM_MXDS_ADAPTER_0);
 	mxm_wmi_call_mxds(mux_id == NOUVEAU_DSM_LED_STAMINA ? MXM_MXDS_ADAPTER_IGD : MXM_MXDS_ADAPTER_0);
 	return nouveau_dsm(handle, NOUVEAU_DSM_LED, mux_id);
 }

 static int nouveau_dsm_set_discrete_state(acpi_handle handle, enum vga_switcheroo_state state)
 {
 	int arg;
 	if (state == VGA_SWITCHEROO_ON)
 		arg = NOUVEAU_DSM_POWER_SPEED;
 	else
 		arg = NOUVEAU_DSM_POWER_STAMINA;
 	nouveau_dsm(handle, NOUVEAU_DSM_POWER, arg);
 	return 0;
 }

 static int nouveau_dsm_switchto(enum vga_switcheroo_client_id id)
 {
 	if (!nouveau_dsm_priv.dsm_detected)
 		return 0;
 	if (id == VGA_SWITCHEROO_IGD)
 		return nouveau_dsm_switch_mux(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_LED_STAMINA);
 	else
 		return nouveau_dsm_switch_mux(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_LED_SPEED);
 }

 static int nouveau_dsm_power_state(enum vga_switcheroo_client_id id,
 				   enum vga_switcheroo_state state)
 {
 	if (id == VGA_SWITCHEROO_IGD)
 		return 0;

 	/* Optimus laptops have the card already disabled in
 	 * nouveau_switcheroo_set_state */
 	if (!nouveau_dsm_priv.dsm_detected)
 		return 0;

 	return nouveau_dsm_set_discrete_state(nouveau_dsm_priv.dhandle, state);
 }

 static enum vga_switcheroo_client_id nouveau_dsm_get_client_id(struct pci_dev *pdev)
 {
 	/* easy option one - intel vendor ID means Integrated */
 	if (pdev->vendor == PCI_VENDOR_ID_INTEL)
 		return VGA_SWITCHEROO_IGD;

 	/* is this device on Bus 0? - this may need improving */
 	if (pdev->bus->number == 0)
 		return VGA_SWITCHEROO_IGD;

 	return VGA_SWITCHEROO_DIS;
 }

 static const struct vga_switcheroo_handler nouveau_dsm_handler = {
 	.switchto = nouveau_dsm_switchto,
 	.power_state = nouveau_dsm_power_state,
 	.get_client_id = nouveau_dsm_get_client_id,
 };

 /*
  * Firmware supporting Windows 8 or later do not use _DSM to put the device into
  * D3cold, they instead rely on disabling power resources on the parent.
  */
 static bool nouveau_pr3_present(struct pci_dev *pdev)
 {
 	struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
 	struct acpi_device *parent_adev;

 	if (!parent_pdev)
 		return false;

 	if (!parent_pdev->bridge_d3) {
 		/*
 		 * Parent PCI bridge is currently not power managed.
 		 * Since userspace can change these afterwards to be on
 		 * the safe side we stick with _DSM and prevent usage of
 		 * _PR3 from the bridge.
 		 */
 		pci_d3cold_disable(pdev);
 		return false;
 	}

 	parent_adev = ACPI_COMPANION(&parent_pdev->dev);
 	if (!parent_adev)
 		return false;

 	return parent_adev->power.flags.power_resources &&
 		acpi_has_method(parent_adev->handle, "_PR3");
 }

 static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle *dhandle_out,
 				  bool *has_mux, bool *has_opt,
 				  bool *has_opt_flags, bool *has_pr3)
 {
 	acpi_handle dhandle;
 	bool supports_mux;
 	int optimus_funcs;

 	dhandle = ACPI_HANDLE(&pdev->dev);
 	if (!dhandle)
 		return;

 	if (!acpi_has_method(dhandle, "_DSM"))
 		return;

 	supports_mux = acpi_check_dsm(dhandle, &nouveau_dsm_muid, 0x00000102,
 				      1 << NOUVEAU_DSM_POWER);
 	optimus_funcs = nouveau_dsm_get_optimus_functions(dhandle);

 	/* Does not look like a Nvidia device. */
 	if (!supports_mux && !optimus_funcs)
 		return;

 	*dhandle_out = dhandle;
 	*has_mux = supports_mux;
 	*has_opt = !!optimus_funcs;
 	*has_opt_flags = optimus_funcs & (1 << NOUVEAU_DSM_OPTIMUS_FLAGS);
 	*has_pr3 = false;

 	if (optimus_funcs) {
 		uint32_t result;
 		nouveau_optimus_dsm(dhandle, NOUVEAU_DSM_OPTIMUS_CAPS, 0,
 				    &result);
 		dev_info(&pdev->dev, "optimus capabilities: %s, status %s%s\n",
 			 (result & OPTIMUS_ENABLED) ? "enabled" : "disabled",
 			 (result & OPTIMUS_DYNAMIC_PWR_CAP) ? "dynamic power, " : "",
 			 (result & OPTIMUS_HDA_CODEC_MASK) ? "hda bios codec supported" : "");

 		*has_pr3 = nouveau_pr3_present(pdev);
 	}
 }

 static bool nouveau_dsm_detect(void)
 {
 	char acpi_method_name[255] = { 0 };
 	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
 	struct pci_dev *pdev = NULL;
 	acpi_handle dhandle = NULL;
 	bool has_mux = false;
 	bool has_optimus = false;
 	bool has_optimus_flags = false;
 	bool has_power_resources = false;
 	int vga_count = 0;
 	bool guid_valid;
 	bool ret = false;

 	/* lookup the MXM GUID */
 	guid_valid = mxm_wmi_supported();

 	if (guid_valid)
 		printk("MXM: GUID detected in BIOS\n");

 	/* now do DSM detection */
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
 		vga_count++;

 		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
 				      &has_optimus_flags, &has_power_resources);
 	}

 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL) {
 		vga_count++;

 		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
 				      &has_optimus_flags, &has_power_resources);
 	}

 	/* find the optimus DSM or the old v1 DSM */
 	if (has_optimus) {
 		nouveau_dsm_priv.dhandle = dhandle;
 		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
 			&buffer);
 		pr_info("VGA switcheroo: detected Optimus DSM method %s handle\n",
 			acpi_method_name);
 		if (has_power_resources)
 			pr_info("nouveau: detected PR support, will not use DSM\n");
 		nouveau_dsm_priv.optimus_detected = true;
 		nouveau_dsm_priv.optimus_flags_detected = has_optimus_flags;
 		nouveau_dsm_priv.optimus_skip_dsm = has_power_resources;
 		ret = true;
 	} else if (vga_count == 2 && has_mux && guid_valid) {
 		nouveau_dsm_priv.dhandle = dhandle;
 		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
 			&buffer);
 		pr_info("VGA switcheroo: detected DSM switching method %s handle\n",
 			acpi_method_name);
 		nouveau_dsm_priv.dsm_detected = true;
 		ret = true;
 	}


 	return ret;
 }

 void nouveau_register_dsm_handler(void)
 {
 	bool r;

 	r = nouveau_dsm_detect();
 	if (!r)
 		return;

 	vga_switcheroo_register_handler(&nouveau_dsm_handler, 0);
 }

 /* Must be called for Optimus models before the card can be turned off */
 void nouveau_switcheroo_optimus_dsm(void)
 {
 	u32 result = 0;
 	if (!nouveau_dsm_priv.optimus_detected || nouveau_dsm_priv.optimus_skip_dsm)
 		return;

 	if (nouveau_dsm_priv.optimus_flags_detected)
 		nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_FLAGS,
 				    0x3, &result);

 	nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_CAPS,
 		NOUVEAU_DSM_OPTIMUS_SET_POWERDOWN, &result);

 }

 void nouveau_unregister_dsm_handler(void)
 {
 	if (nouveau_dsm_priv.optimus_detected || nouveau_dsm_priv.dsm_detected)
 		vga_switcheroo_unregister_handler();
 }
 #else
 void nouveau_register_dsm_handler(void) {}
 void nouveau_unregister_dsm_handler(void) {}
 void nouveau_switcheroo_optimus_dsm(void) {}
 #endif

 /* retrieve the ROM in 4k blocks */
 static int nouveau_rom_call(acpi_handle rom_handle, uint8_t *bios,
 			    int offset, int len)
 {
 	acpi_status status;
 	union acpi_object rom_arg_elements[2], *obj;
 	struct acpi_object_list rom_arg;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL};

 	rom_arg.count = 2;
 	rom_arg.pointer = &rom_arg_elements[0];

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

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

 	status = acpi_evaluate_object(rom_handle, NULL, &rom_arg, &buffer);
 	if (ACPI_FAILURE(status)) {
 		pr_info("failed to evaluate ROM got %s\n",
 			acpi_format_exception(status));
 		return -ENODEV;
 	}
 	obj = (union acpi_object *)buffer.pointer;
 	len = min(len, (int)obj->buffer.length);
 	memcpy(bios+offset, obj->buffer.pointer, len);
 	kfree(buffer.pointer);
 	return len;
 }

 bool nouveau_acpi_rom_supported(struct device *dev)
 {
 	acpi_status status;
 	acpi_handle dhandle, rom_handle;

 	dhandle = ACPI_HANDLE(dev);
 	if (!dhandle)
 		return false;

 	status = acpi_get_handle(dhandle, "_ROM", &rom_handle);
 	if (ACPI_FAILURE(status))
 		return false;

 	nouveau_dsm_priv.rom_handle = rom_handle;
 	return true;
 }

 int nouveau_acpi_get_bios_chunk(uint8_t *bios, int offset, int len)
 {
 	return nouveau_rom_call(nouveau_dsm_priv.rom_handle, bios, offset, len);
 }

 void *
 nouveau_acpi_edid(struct drm_device *dev, struct drm_connector *connector)
 {
 	struct acpi_device *acpidev;
 	acpi_handle handle;
 	int type, ret;
 	void *edid;

 	switch (connector->connector_type) {
 	case DRM_MODE_CONNECTOR_LVDS:
 	case DRM_MODE_CONNECTOR_eDP:
 		type = ACPI_VIDEO_DISPLAY_LCD;
 		break;
 	default:
 		return NULL;
 	}

 	handle = ACPI_HANDLE(&dev->pdev->dev);
 	if (!handle)
 		return NULL;

 	ret = acpi_bus_get_device(handle, &acpidev);
 	if (ret)
 		return NULL;

 	ret = acpi_video_get_edid(acpidev, type, -1, &edid);
 	if (ret < 0)
 		return NULL;

 	return kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
 }
	// SPDX-License-Identifier: GPL-2.0
	#include <linux/pci.h>
	#include <linux/acpi.h>
	#include <linux/slab.h>
	#include <linux/mxm-wmi.h>
	#include <linux/vga_switcheroo.h>
	#include <drm/drm_edid.h>
	#include <acpi/video.h>

	#include "nouveau_drv.h"
	#include "nouveau_acpi.h"

	#define NOUVEAU_DSM_LED 0x02
	#define NOUVEAU_DSM_LED_STATE 0x00
	#define NOUVEAU_DSM_LED_OFF 0x10
	#define NOUVEAU_DSM_LED_STAMINA 0x11
	#define NOUVEAU_DSM_LED_SPEED 0x12

	#define NOUVEAU_DSM_POWER 0x03
	#define NOUVEAU_DSM_POWER_STATE 0x00
	#define NOUVEAU_DSM_POWER_SPEED 0x01
	#define NOUVEAU_DSM_POWER_STAMINA 0x02

	#define NOUVEAU_DSM_OPTIMUS_CAPS 0x1A
	#define NOUVEAU_DSM_OPTIMUS_FLAGS 0x1B

	#define NOUVEAU_DSM_OPTIMUS_POWERDOWN_PS3 (3 << 24)
	#define NOUVEAU_DSM_OPTIMUS_NO_POWERDOWN_PS3 (2 << 24)
	#define NOUVEAU_DSM_OPTIMUS_FLAGS_CHANGED (1)

	#define NOUVEAU_DSM_OPTIMUS_SET_POWERDOWN (NOUVEAU_DSM_OPTIMUS_POWERDOWN_PS3 \| NOUVEAU_DSM_OPTIMUS_FLAGS_CHANGED)

	/* result of the optimus caps function */
	#define OPTIMUS_ENABLED (1 << 0)
	#define OPTIMUS_STATUS_MASK (3 << 3)
	#define OPTIMUS_STATUS_OFF (0 << 3)
	#define OPTIMUS_STATUS_ON_ENABLED (1 << 3)
	#define OPTIMUS_STATUS_PWR_STABLE (3 << 3)
	#define OPTIMUS_DISPLAY_HOTPLUG (1 << 6)
	#define OPTIMUS_CAPS_MASK (7 << 24)
	#define OPTIMUS_DYNAMIC_PWR_CAP (1 << 24)

	#define OPTIMUS_AUDIO_CAPS_MASK (3 << 27)
	#define OPTIMUS_HDA_CODEC_MASK (2 << 27) /* hda bios control */

	static struct nouveau_dsm_priv {
	bool dsm_detected;
	bool optimus_detected;
	bool optimus_flags_detected;
	bool optimus_skip_dsm;
	acpi_handle dhandle;
	acpi_handle rom_handle;
	} nouveau_dsm_priv;

	bool nouveau_is_optimus(void) {
	return nouveau_dsm_priv.optimus_detected;
	}

	bool nouveau_is_v1_dsm(void) {
	return nouveau_dsm_priv.dsm_detected;
	}

	#ifdef CONFIG_VGA_SWITCHEROO
	static const guid_t nouveau_dsm_muid =
	GUID_INIT(0x9D95A0A0, 0x0060, 0x4D48,
	0xB3, 0x4D, 0x7E, 0x5F, 0xEA, 0x12, 0x9F, 0xD4);

	static const guid_t nouveau_op_dsm_muid =
	GUID_INIT(0xA486D8F8, 0x0BDA, 0x471B,
	0xA7, 0x2B, 0x60, 0x42, 0xA6, 0xB5, 0xBE, 0xE0);

	static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t *result)
	{
	int i;
	union acpi_object *obj;
	char args_buff[4];
	union acpi_object argv4 = {
	.buffer.type = ACPI_TYPE_BUFFER,
	.buffer.length = 4,
	.buffer.pointer = args_buff
	};

	/* ACPI is little endian, AABBCCDD becomes {DD,CC,BB,AA} */
	for (i = 0; i < 4; i++)
	args_buff[i] = (arg >> i * 8) & 0xFF;

	*result = 0;
	obj = acpi_evaluate_dsm_typed(handle, &nouveau_op_dsm_muid, 0x00000100,
	func, &argv4, ACPI_TYPE_BUFFER);
	if (!obj) {
	acpi_handle_info(handle, "failed to evaluate _DSM\n");
	return AE_ERROR;
	} else {
	if (obj->buffer.length == 4) {
	*result \|= obj->buffer.pointer[0];
	*result \|= (obj->buffer.pointer[1] << 8);
	*result \|= (obj->buffer.pointer[2] << 16);
	*result \|= (obj->buffer.pointer[3] << 24);
	}
	ACPI_FREE(obj);
	}

	return 0;
	}

	/*
	* On some platforms, _DSM(nouveau_op_dsm_muid, func0) has special
	* requirements on the fourth parameter, so a private implementation
	* instead of using acpi_check_dsm().
	*/
	static int nouveau_dsm_get_optimus_functions(acpi_handle handle)
	{
	int result;

	/*
	* Function 0 returns a Buffer containing available functions.
	* The args parameter is ignored for function 0, so just put 0 in it
	*/
	if (nouveau_optimus_dsm(handle, 0, 0, &result))
	return 0;

	/*
	* ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported.
	* If the n-th bit is enabled, function n is supported
	*/
	if (result & 1 && result & (1 << NOUVEAU_DSM_OPTIMUS_CAPS))
	return result;
	return 0;
	}

	static int nouveau_dsm(acpi_handle handle, int func, int arg)
	{
	int ret = 0;
	union acpi_object *obj;
	union acpi_object argv4 = {
	.integer.type = ACPI_TYPE_INTEGER,
	.integer.value = arg,
	};

	obj = acpi_evaluate_dsm_typed(handle, &nouveau_dsm_muid, 0x00000102,
	func, &argv4, ACPI_TYPE_INTEGER);
	if (!obj) {
	acpi_handle_info(handle, "failed to evaluate _DSM\n");
	return AE_ERROR;
	} else {
	if (obj->integer.value == 0x80000002)
	ret = -ENODEV;
	ACPI_FREE(obj);
	}

	return ret;
	}

	static int nouveau_dsm_switch_mux(acpi_handle handle, int mux_id)
	{
	mxm_wmi_call_mxmx(mux_id == NOUVEAU_DSM_LED_STAMINA ? MXM_MXDS_ADAPTER_IGD : MXM_MXDS_ADAPTER_0);
	mxm_wmi_call_mxds(mux_id == NOUVEAU_DSM_LED_STAMINA ? MXM_MXDS_ADAPTER_IGD : MXM_MXDS_ADAPTER_0);
	return nouveau_dsm(handle, NOUVEAU_DSM_LED, mux_id);
	}

	static int nouveau_dsm_set_discrete_state(acpi_handle handle, enum vga_switcheroo_state state)
	{
	int arg;
	if (state == VGA_SWITCHEROO_ON)
	arg = NOUVEAU_DSM_POWER_SPEED;
	else
	arg = NOUVEAU_DSM_POWER_STAMINA;
	nouveau_dsm(handle, NOUVEAU_DSM_POWER, arg);
	return 0;
	}

	static int nouveau_dsm_switchto(enum vga_switcheroo_client_id id)
	{
	if (!nouveau_dsm_priv.dsm_detected)
	return 0;
	if (id == VGA_SWITCHEROO_IGD)
	return nouveau_dsm_switch_mux(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_LED_STAMINA);
	else
	return nouveau_dsm_switch_mux(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_LED_SPEED);
	}

	static int nouveau_dsm_power_state(enum vga_switcheroo_client_id id,
	enum vga_switcheroo_state state)
	{
	if (id == VGA_SWITCHEROO_IGD)
	return 0;

	/* Optimus laptops have the card already disabled in
	* nouveau_switcheroo_set_state */
	if (!nouveau_dsm_priv.dsm_detected)
	return 0;

	return nouveau_dsm_set_discrete_state(nouveau_dsm_priv.dhandle, state);
	}

	static enum vga_switcheroo_client_id nouveau_dsm_get_client_id(struct pci_dev *pdev)
	{
	/* easy option one - intel vendor ID means Integrated */
	if (pdev->vendor == PCI_VENDOR_ID_INTEL)
	return VGA_SWITCHEROO_IGD;

	/* is this device on Bus 0? - this may need improving */
	if (pdev->bus->number == 0)
	return VGA_SWITCHEROO_IGD;

	return VGA_SWITCHEROO_DIS;
	}

	static const struct vga_switcheroo_handler nouveau_dsm_handler = {
	.switchto = nouveau_dsm_switchto,
	.power_state = nouveau_dsm_power_state,
	.get_client_id = nouveau_dsm_get_client_id,
	};

	/*
	* Firmware supporting Windows 8 or later do not use _DSM to put the device into
	* D3cold, they instead rely on disabling power resources on the parent.
	*/
	static bool nouveau_pr3_present(struct pci_dev *pdev)
	{
	struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
	struct acpi_device *parent_adev;

	if (!parent_pdev)
	return false;

	if (!parent_pdev->bridge_d3) {
	/*
	* Parent PCI bridge is currently not power managed.
	* Since userspace can change these afterwards to be on
	* the safe side we stick with _DSM and prevent usage of
	* _PR3 from the bridge.
	*/
	pci_d3cold_disable(pdev);
	return false;
	}

	parent_adev = ACPI_COMPANION(&parent_pdev->dev);
	if (!parent_adev)
	return false;

	return parent_adev->power.flags.power_resources &&
	acpi_has_method(parent_adev->handle, "_PR3");
	}

	static void nouveau_dsm_pci_probe(struct pci_dev pdev, acpi_handle dhandle_out,
	bool has_mux, bool has_opt,
	bool has_opt_flags, bool has_pr3)
	{
	acpi_handle dhandle;
	bool supports_mux;
	int optimus_funcs;

	dhandle = ACPI_HANDLE(&pdev->dev);
	if (!dhandle)
	return;

	if (!acpi_has_method(dhandle, "_DSM"))
	return;

	supports_mux = acpi_check_dsm(dhandle, &nouveau_dsm_muid, 0x00000102,
	1 << NOUVEAU_DSM_POWER);
	optimus_funcs = nouveau_dsm_get_optimus_functions(dhandle);

	/* Does not look like a Nvidia device. */
	if (!supports_mux && !optimus_funcs)
	return;

	*dhandle_out = dhandle;
	*has_mux = supports_mux;
	*has_opt = !!optimus_funcs;
	*has_opt_flags = optimus_funcs & (1 << NOUVEAU_DSM_OPTIMUS_FLAGS);
	*has_pr3 = false;

	if (optimus_funcs) {
	uint32_t result;
	nouveau_optimus_dsm(dhandle, NOUVEAU_DSM_OPTIMUS_CAPS, 0,
	&result);
	dev_info(&pdev->dev, "optimus capabilities: %s, status %s%s\n",
	(result & OPTIMUS_ENABLED) ? "enabled" : "disabled",
	(result & OPTIMUS_DYNAMIC_PWR_CAP) ? "dynamic power, " : "",
	(result & OPTIMUS_HDA_CODEC_MASK) ? "hda bios codec supported" : "");

	*has_pr3 = nouveau_pr3_present(pdev);
	}
	}

	static bool nouveau_dsm_detect(void)
	{
	char acpi_method_name[255] = { 0 };
	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
	struct pci_dev *pdev = NULL;
	acpi_handle dhandle = NULL;
	bool has_mux = false;
	bool has_optimus = false;
	bool has_optimus_flags = false;
	bool has_power_resources = false;
	int vga_count = 0;
	bool guid_valid;
	bool ret = false;

	/* lookup the MXM GUID */
	guid_valid = mxm_wmi_supported();

	if (guid_valid)
	printk("MXM: GUID detected in BIOS\n");

	/* now do DSM detection */
	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
	vga_count++;

	nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
	&has_optimus_flags, &has_power_resources);
	}

	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL) {
	vga_count++;

	nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
	&has_optimus_flags, &has_power_resources);
	}

	/* find the optimus DSM or the old v1 DSM */
	if (has_optimus) {
	nouveau_dsm_priv.dhandle = dhandle;
	acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
	&buffer);
	pr_info("VGA switcheroo: detected Optimus DSM method %s handle\n",
	acpi_method_name);
	if (has_power_resources)
	pr_info("nouveau: detected PR support, will not use DSM\n");
	nouveau_dsm_priv.optimus_detected = true;
	nouveau_dsm_priv.optimus_flags_detected = has_optimus_flags;
	nouveau_dsm_priv.optimus_skip_dsm = has_power_resources;
	ret = true;
	} else if (vga_count == 2 && has_mux && guid_valid) {
	nouveau_dsm_priv.dhandle = dhandle;
	acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
	&buffer);
	pr_info("VGA switcheroo: detected DSM switching method %s handle\n",
	acpi_method_name);
	nouveau_dsm_priv.dsm_detected = true;
	ret = true;
	}


	return ret;
	}

	void nouveau_register_dsm_handler(void)
	{
	bool r;

	r = nouveau_dsm_detect();
	if (!r)
	return;

	vga_switcheroo_register_handler(&nouveau_dsm_handler, 0);
	}

	/* Must be called for Optimus models before the card can be turned off */
	void nouveau_switcheroo_optimus_dsm(void)
	{
	u32 result = 0;
	if (!nouveau_dsm_priv.optimus_detected \|\| nouveau_dsm_priv.optimus_skip_dsm)
	return;

	if (nouveau_dsm_priv.optimus_flags_detected)
	nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_FLAGS,
	0x3, &result);

	nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_CAPS,
	NOUVEAU_DSM_OPTIMUS_SET_POWERDOWN, &result);

	}

	void nouveau_unregister_dsm_handler(void)
	{
	if (nouveau_dsm_priv.optimus_detected \|\| nouveau_dsm_priv.dsm_detected)
	vga_switcheroo_unregister_handler();
	}
	#else
	void nouveau_register_dsm_handler(void) {}
	void nouveau_unregister_dsm_handler(void) {}
	void nouveau_switcheroo_optimus_dsm(void) {}
	#endif

	/* retrieve the ROM in 4k blocks */
	static int nouveau_rom_call(acpi_handle rom_handle, uint8_t *bios,
	int offset, int len)
	{
	acpi_status status;
	union acpi_object rom_arg_elements[2], *obj;
	struct acpi_object_list rom_arg;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL};

	rom_arg.count = 2;
	rom_arg.pointer = &rom_arg_elements[0];

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

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

	status = acpi_evaluate_object(rom_handle, NULL, &rom_arg, &buffer);
	if (ACPI_FAILURE(status)) {
	pr_info("failed to evaluate ROM got %s\n",
	acpi_format_exception(status));
	return -ENODEV;
	}
	obj = (union acpi_object *)buffer.pointer;
	len = min(len, (int)obj->buffer.length);
	memcpy(bios+offset, obj->buffer.pointer, len);
	kfree(buffer.pointer);
	return len;
	}

	bool nouveau_acpi_rom_supported(struct device *dev)
	{
	acpi_status status;
	acpi_handle dhandle, rom_handle;

	dhandle = ACPI_HANDLE(dev);
	if (!dhandle)
	return false;

	status = acpi_get_handle(dhandle, "_ROM", &rom_handle);
	if (ACPI_FAILURE(status))
	return false;

	nouveau_dsm_priv.rom_handle = rom_handle;
	return true;
	}

	int nouveau_acpi_get_bios_chunk(uint8_t *bios, int offset, int len)
	{
	return nouveau_rom_call(nouveau_dsm_priv.rom_handle, bios, offset, len);
	}

	void *
	nouveau_acpi_edid(struct drm_device dev, struct drm_connector connector)
	{
	struct acpi_device *acpidev;
	acpi_handle handle;
	int type, ret;
	void *edid;

	switch (connector->connector_type) {
	case DRM_MODE_CONNECTOR_LVDS:
	case DRM_MODE_CONNECTOR_eDP:
	type = ACPI_VIDEO_DISPLAY_LCD;
	break;
	default:
	return NULL;
	}

	handle = ACPI_HANDLE(&dev->pdev->dev);
	if (!handle)
	return NULL;

	ret = acpi_bus_get_device(handle, &acpidev);
	if (ret)
	return NULL;

	ret = acpi_video_get_edid(acpidev, type, -1, &edid);
	if (ret < 0)
	return NULL;

	return kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
	}