drivers/gpu/drm/radeon/radeon_atpx_handler.c - linux - Git at Google

 /*
  * Copyright (c) 2010 Red Hat Inc.
  * Author : Dave Airlie <airlied@redhat.com>
  *
  * Licensed under GPLv2
  *
  * ATPX support for both Intel/ATI
  */
 #include <linux/vga_switcheroo.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/pci.h>

 #include "radeon_acpi.h"

 struct radeon_atpx_functions {
 	bool px_params;
 	bool power_cntl;
 	bool disp_mux_cntl;
 	bool i2c_mux_cntl;
 	bool switch_start;
 	bool switch_end;
 	bool disp_connectors_mapping;
 	bool disp_detetion_ports;
 };

 struct radeon_atpx {
 	acpi_handle handle;
 	struct radeon_atpx_functions functions;
 };

 static struct radeon_atpx_priv {
 	bool atpx_detected;
 	/* handle for device - and atpx */
 	acpi_handle dhandle;
 	acpi_handle other_handle;
 	struct radeon_atpx atpx;
 } radeon_atpx_priv;

 struct atpx_verify_interface {
 	u16 size;		/* structure size in bytes (includes size field) */
 	u16 version;		/* version */
 	u32 function_bits;	/* supported functions bit vector */
 } __packed;

 struct atpx_px_params {
 	u16 size;		/* structure size in bytes (includes size field) */
 	u32 valid_flags;	/* which flags are valid */
 	u32 flags;		/* flags */
 } __packed;

 struct atpx_power_control {
 	u16 size;
 	u8 dgpu_state;
 } __packed;

 struct atpx_mux {
 	u16 size;
 	u16 mux;
 } __packed;

 bool radeon_has_atpx(void) {
 	return radeon_atpx_priv.atpx_detected;
 }

 /**
  * radeon_atpx_call - call an ATPX method
  *
  * @handle: acpi handle
  * @function: the ATPX function to execute
  * @params: ATPX function params
  *
  * Executes the requested ATPX function (all asics).
  * Returns a pointer to the acpi output buffer.
  */
 static union acpi_object *radeon_atpx_call(acpi_handle handle, int function,
 					   struct acpi_buffer *params)
 {
 	acpi_status status;
 	union acpi_object atpx_arg_elements[2];
 	struct acpi_object_list atpx_arg;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

 	atpx_arg.count = 2;
 	atpx_arg.pointer = &atpx_arg_elements[0];

 	atpx_arg_elements[0].type = ACPI_TYPE_INTEGER;
 	atpx_arg_elements[0].integer.value = function;

 	if (params) {
 		atpx_arg_elements[1].type = ACPI_TYPE_BUFFER;
 		atpx_arg_elements[1].buffer.length = params->length;
 		atpx_arg_elements[1].buffer.pointer = params->pointer;
 	} else {
 		/* We need a second fake parameter */
 		atpx_arg_elements[1].type = ACPI_TYPE_INTEGER;
 		atpx_arg_elements[1].integer.value = 0;
 	}

 	status = acpi_evaluate_object(handle, NULL, &atpx_arg, &buffer);

 	/* Fail only if calling the method fails and ATPX is supported */
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 		printk("failed to evaluate ATPX got %s\n",
 		       acpi_format_exception(status));
 		kfree(buffer.pointer);
 		return NULL;
 	}

 	return buffer.pointer;
 }

 /**
  * radeon_atpx_parse_functions - parse supported functions
  *
  * @f: supported functions struct
  * @mask: supported functions mask from ATPX
  *
  * Use the supported functions mask from ATPX function
  * ATPX_FUNCTION_VERIFY_INTERFACE to determine what functions
  * are supported (all asics).
  */
 static void radeon_atpx_parse_functions(struct radeon_atpx_functions *f, u32 mask)
 {
 	f->px_params = mask & ATPX_GET_PX_PARAMETERS_SUPPORTED;
 	f->power_cntl = mask & ATPX_POWER_CONTROL_SUPPORTED;
 	f->disp_mux_cntl = mask & ATPX_DISPLAY_MUX_CONTROL_SUPPORTED;
 	f->i2c_mux_cntl = mask & ATPX_I2C_MUX_CONTROL_SUPPORTED;
 	f->switch_start = mask & ATPX_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION_SUPPORTED;
 	f->switch_end = mask & ATPX_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION_SUPPORTED;
 	f->disp_connectors_mapping = mask & ATPX_GET_DISPLAY_CONNECTORS_MAPPING_SUPPORTED;
 	f->disp_detetion_ports = mask & ATPX_GET_DISPLAY_DETECTION_PORTS_SUPPORTED;
 }

 /**
  * radeon_atpx_validate_functions - validate ATPX functions
  *
  * @atpx: radeon atpx struct
  *
  * Validate that required functions are enabled (all asics).
  * returns 0 on success, error on failure.
  */
 static int radeon_atpx_validate(struct radeon_atpx *atpx)
 {
 	/* make sure required functions are enabled */
 	/* dGPU power control is required */
 	atpx->functions.power_cntl = true;

 	if (atpx->functions.px_params) {
 		union acpi_object *info;
 		struct atpx_px_params output;
 		size_t size;
 		u32 valid_bits;

 		info = radeon_atpx_call(atpx->handle, ATPX_FUNCTION_GET_PX_PARAMETERS, NULL);
 		if (!info)
 			return -EIO;

 		memset(&output, 0, sizeof(output));

 		size = *(u16 *) info->buffer.pointer;
 		if (size < 10) {
 			printk("ATPX buffer is too small: %zu\n", size);
 			kfree(info);
 			return -EINVAL;
 		}
 		size = min(sizeof(output), size);

 		memcpy(&output, info->buffer.pointer, size);

 		valid_bits = output.flags & output.valid_flags;
 		/* if separate mux flag is set, mux controls are required */
 		if (valid_bits & ATPX_SEPARATE_MUX_FOR_I2C) {
 			atpx->functions.i2c_mux_cntl = true;
 			atpx->functions.disp_mux_cntl = true;
 		}
 		/* if any outputs are muxed, mux controls are required */
 		if (valid_bits & (ATPX_CRT1_RGB_SIGNAL_MUXED |
 				  ATPX_TV_SIGNAL_MUXED |
 				  ATPX_DFP_SIGNAL_MUXED))
 			atpx->functions.disp_mux_cntl = true;

 		kfree(info);
 	}
 	return 0;
 }

 /**
  * radeon_atpx_verify_interface - verify ATPX
  *
  * @atpx: radeon atpx struct
  *
  * Execute the ATPX_FUNCTION_VERIFY_INTERFACE ATPX function
  * to initialize ATPX and determine what features are supported
  * (all asics).
  * returns 0 on success, error on failure.
  */
 static int radeon_atpx_verify_interface(struct radeon_atpx *atpx)
 {
 	union acpi_object *info;
 	struct atpx_verify_interface output;
 	size_t size;
 	int err = 0;

 	info = radeon_atpx_call(atpx->handle, ATPX_FUNCTION_VERIFY_INTERFACE, NULL);
 	if (!info)
 		return -EIO;

 	memset(&output, 0, sizeof(output));

 	size = *(u16 *) info->buffer.pointer;
 	if (size < 8) {
 		printk("ATPX buffer is too small: %zu\n", size);
 		err = -EINVAL;
 		goto out;
 	}
 	size = min(sizeof(output), size);

 	memcpy(&output, info->buffer.pointer, size);

 	/* TODO: check version? */
 	printk("ATPX version %u, functions 0x%08x\n",
 	       output.version, output.function_bits);

 	radeon_atpx_parse_functions(&atpx->functions, output.function_bits);

 out:
 	kfree(info);
 	return err;
 }

 /**
  * radeon_atpx_set_discrete_state - power up/down discrete GPU
  *
  * @atpx: atpx info struct
  * @state: discrete GPU state (0 = power down, 1 = power up)
  *
  * Execute the ATPX_FUNCTION_POWER_CONTROL ATPX function to
  * power down/up the discrete GPU (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_set_discrete_state(struct radeon_atpx *atpx, u8 state)
 {
 	struct acpi_buffer params;
 	union acpi_object *info;
 	struct atpx_power_control input;

 	if (atpx->functions.power_cntl) {
 		input.size = 3;
 		input.dgpu_state = state;
 		params.length = input.size;
 		params.pointer = &input;
 		info = radeon_atpx_call(atpx->handle,
 					ATPX_FUNCTION_POWER_CONTROL,
 					&params);
 		if (!info)
 			return -EIO;
 		kfree(info);
 	}
 	return 0;
 }

 /**
  * radeon_atpx_switch_disp_mux - switch display mux
  *
  * @atpx: atpx info struct
  * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
  *
  * Execute the ATPX_FUNCTION_DISPLAY_MUX_CONTROL ATPX function to
  * switch the display mux between the discrete GPU and integrated GPU
  * (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_switch_disp_mux(struct radeon_atpx *atpx, u16 mux_id)
 {
 	struct acpi_buffer params;
 	union acpi_object *info;
 	struct atpx_mux input;

 	if (atpx->functions.disp_mux_cntl) {
 		input.size = 4;
 		input.mux = mux_id;
 		params.length = input.size;
 		params.pointer = &input;
 		info = radeon_atpx_call(atpx->handle,
 					ATPX_FUNCTION_DISPLAY_MUX_CONTROL,
 					&params);
 		if (!info)
 			return -EIO;
 		kfree(info);
 	}
 	return 0;
 }

 /**
  * radeon_atpx_switch_i2c_mux - switch i2c/hpd mux
  *
  * @atpx: atpx info struct
  * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
  *
  * Execute the ATPX_FUNCTION_I2C_MUX_CONTROL ATPX function to
  * switch the i2c/hpd mux between the discrete GPU and integrated GPU
  * (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_switch_i2c_mux(struct radeon_atpx *atpx, u16 mux_id)
 {
 	struct acpi_buffer params;
 	union acpi_object *info;
 	struct atpx_mux input;

 	if (atpx->functions.i2c_mux_cntl) {
 		input.size = 4;
 		input.mux = mux_id;
 		params.length = input.size;
 		params.pointer = &input;
 		info = radeon_atpx_call(atpx->handle,
 					ATPX_FUNCTION_I2C_MUX_CONTROL,
 					&params);
 		if (!info)
 			return -EIO;
 		kfree(info);
 	}
 	return 0;
 }

 /**
  * radeon_atpx_switch_start - notify the sbios of a GPU switch
  *
  * @atpx: atpx info struct
  * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
  *
  * Execute the ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION ATPX
  * function to notify the sbios that a switch between the discrete GPU and
  * integrated GPU has begun (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_switch_start(struct radeon_atpx *atpx, u16 mux_id)
 {
 	struct acpi_buffer params;
 	union acpi_object *info;
 	struct atpx_mux input;

 	if (atpx->functions.switch_start) {
 		input.size = 4;
 		input.mux = mux_id;
 		params.length = input.size;
 		params.pointer = &input;
 		info = radeon_atpx_call(atpx->handle,
 					ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION,
 					&params);
 		if (!info)
 			return -EIO;
 		kfree(info);
 	}
 	return 0;
 }

 /**
  * radeon_atpx_switch_end - notify the sbios of a GPU switch
  *
  * @atpx: atpx info struct
  * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
  *
  * Execute the ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION ATPX
  * function to notify the sbios that a switch between the discrete GPU and
  * integrated GPU has ended (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_switch_end(struct radeon_atpx *atpx, u16 mux_id)
 {
 	struct acpi_buffer params;
 	union acpi_object *info;
 	struct atpx_mux input;

 	if (atpx->functions.switch_end) {
 		input.size = 4;
 		input.mux = mux_id;
 		params.length = input.size;
 		params.pointer = &input;
 		info = radeon_atpx_call(atpx->handle,
 					ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION,
 					&params);
 		if (!info)
 			return -EIO;
 		kfree(info);
 	}
 	return 0;
 }

 /**
  * radeon_atpx_switchto - switch to the requested GPU
  *
  * @id: GPU to switch to
  *
  * Execute the necessary ATPX functions to switch between the discrete GPU and
  * integrated GPU (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_switchto(enum vga_switcheroo_client_id id)
 {
 	u16 gpu_id;

 	if (id == VGA_SWITCHEROO_IGD)
 		gpu_id = ATPX_INTEGRATED_GPU;
 	else
 		gpu_id = ATPX_DISCRETE_GPU;

 	radeon_atpx_switch_start(&radeon_atpx_priv.atpx, gpu_id);
 	radeon_atpx_switch_disp_mux(&radeon_atpx_priv.atpx, gpu_id);
 	radeon_atpx_switch_i2c_mux(&radeon_atpx_priv.atpx, gpu_id);
 	radeon_atpx_switch_end(&radeon_atpx_priv.atpx, gpu_id);

 	return 0;
 }

 /**
  * radeon_atpx_power_state - power down/up the requested GPU
  *
  * @id: GPU to power down/up
  * @state: requested power state (0 = off, 1 = on)
  *
  * Execute the necessary ATPX function to power down/up the discrete GPU
  * (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_power_state(enum vga_switcheroo_client_id id,
 				   enum vga_switcheroo_state state)
 {
 	/* on w500 ACPI can't change intel gpu state */
 	if (id == VGA_SWITCHEROO_IGD)
 		return 0;

 	radeon_atpx_set_discrete_state(&radeon_atpx_priv.atpx, state);
 	return 0;
 }

 /**
  * radeon_atpx_pci_probe_handle - look up the ATPX handle
  *
  * @pdev: pci device
  *
  * Look up the ATPX handles (all asics).
  * Returns true if the handles are found, false if not.
  */
 static bool radeon_atpx_pci_probe_handle(struct pci_dev *pdev)
 {
 	acpi_handle dhandle, atpx_handle;
 	acpi_status status;

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

 	status = acpi_get_handle(dhandle, "ATPX", &atpx_handle);
 	if (ACPI_FAILURE(status)) {
 		radeon_atpx_priv.other_handle = dhandle;
 		return false;
 	}
 	radeon_atpx_priv.dhandle = dhandle;
 	radeon_atpx_priv.atpx.handle = atpx_handle;
 	return true;
 }

 /**
  * radeon_atpx_init - verify the ATPX interface
  *
  * Verify the ATPX interface (all asics).
  * Returns 0 on success, error on failure.
  */
 static int radeon_atpx_init(void)
 {
 	int r;

 	/* set up the ATPX handle */
 	r = radeon_atpx_verify_interface(&radeon_atpx_priv.atpx);
 	if (r)
 		return r;

 	/* validate the atpx setup */
 	r = radeon_atpx_validate(&radeon_atpx_priv.atpx);
 	if (r)
 		return r;

 	return 0;
 }

 /**
  * radeon_atpx_get_client_id - get the client id
  *
  * @pdev: pci device
  *
  * look up whether we are the integrated or discrete GPU (all asics).
  * Returns the client id.
  */
 static int radeon_atpx_get_client_id(struct pci_dev *pdev)
 {
 	if (radeon_atpx_priv.dhandle == ACPI_HANDLE(&pdev->dev))
 		return VGA_SWITCHEROO_IGD;
 	else
 		return VGA_SWITCHEROO_DIS;
 }

 static struct vga_switcheroo_handler radeon_atpx_handler = {
 	.switchto = radeon_atpx_switchto,
 	.power_state = radeon_atpx_power_state,
 	.init = radeon_atpx_init,
 	.get_client_id = radeon_atpx_get_client_id,
 };

 /**
  * radeon_atpx_detect - detect whether we have PX
  *
  * Check if we have a PX system (all asics).
  * Returns true if we have a PX system, false if not.
  */
 static bool radeon_atpx_detect(void)
 {
 	char acpi_method_name[255] = { 0 };
 	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
 	struct pci_dev *pdev = NULL;
 	bool has_atpx = false;
 	int vga_count = 0;

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

 		has_atpx |= (radeon_atpx_pci_probe_handle(pdev) == true);
 	}

 	if (has_atpx && vga_count == 2) {
 		acpi_get_name(radeon_atpx_priv.atpx.handle, ACPI_FULL_PATHNAME, &buffer);
 		printk(KERN_INFO "VGA switcheroo: detected switching method %s handle\n",
 		       acpi_method_name);
 		radeon_atpx_priv.atpx_detected = true;
 		/*
 		 * On some systems hotplug events are generated for the device
 		 * being switched off when ATPX is executed.  They cause ACPI
 		 * hotplug to trigger and attempt to remove the device from
 		 * the system, which causes it to break down.  Prevent that from
 		 * happening by setting the no_hotplug flag for the involved
 		 * ACPI device objects.
 		 */
 		acpi_bus_no_hotplug(radeon_atpx_priv.dhandle);
 		acpi_bus_no_hotplug(radeon_atpx_priv.other_handle);
 		return true;
 	}
 	return false;
 }

 /**
  * radeon_register_atpx_handler - register with vga_switcheroo
  *
  * Register the PX callbacks with vga_switcheroo (all asics).
  */
 void radeon_register_atpx_handler(void)
 {
 	bool r;

 	/* detect if we have any ATPX + 2 VGA in the system */
 	r = radeon_atpx_detect();
 	if (!r)
 		return;

 	vga_switcheroo_register_handler(&radeon_atpx_handler);
 }

 /**
  * radeon_unregister_atpx_handler - unregister with vga_switcheroo
  *
  * Unregister the PX callbacks with vga_switcheroo (all asics).
  */
 void radeon_unregister_atpx_handler(void)
 {
 	vga_switcheroo_unregister_handler();
 }
	/*
	* Copyright (c) 2010 Red Hat Inc.
	* Author : Dave Airlie <airlied@redhat.com>
	*
	* Licensed under GPLv2
	*
	* ATPX support for both Intel/ATI
	*/
	#include <linux/vga_switcheroo.h>
	#include <linux/slab.h>
	#include <linux/acpi.h>
	#include <linux/pci.h>

	#include "radeon_acpi.h"

	struct radeon_atpx_functions {
	bool px_params;
	bool power_cntl;
	bool disp_mux_cntl;
	bool i2c_mux_cntl;
	bool switch_start;
	bool switch_end;
	bool disp_connectors_mapping;
	bool disp_detetion_ports;
	};

	struct radeon_atpx {
	acpi_handle handle;
	struct radeon_atpx_functions functions;
	};

	static struct radeon_atpx_priv {
	bool atpx_detected;
	/* handle for device - and atpx */
	acpi_handle dhandle;
	acpi_handle other_handle;
	struct radeon_atpx atpx;
	} radeon_atpx_priv;

	struct atpx_verify_interface {
	u16 size; /* structure size in bytes (includes size field) */
	u16 version; /* version */
	u32 function_bits; /* supported functions bit vector */
	} __packed;

	struct atpx_px_params {
	u16 size; /* structure size in bytes (includes size field) */
	u32 valid_flags; /* which flags are valid */
	u32 flags; /* flags */
	} __packed;

	struct atpx_power_control {
	u16 size;
	u8 dgpu_state;
	} __packed;

	struct atpx_mux {
	u16 size;
	u16 mux;
	} __packed;

	bool radeon_has_atpx(void) {
	return radeon_atpx_priv.atpx_detected;
	}

	/**
	* radeon_atpx_call - call an ATPX method
	*
	* @handle: acpi handle
	* @function: the ATPX function to execute
	* @params: ATPX function params
	*
	* Executes the requested ATPX function (all asics).
	* Returns a pointer to the acpi output buffer.
	*/
	static union acpi_object *radeon_atpx_call(acpi_handle handle, int function,
	struct acpi_buffer *params)
	{
	acpi_status status;
	union acpi_object atpx_arg_elements[2];
	struct acpi_object_list atpx_arg;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

	atpx_arg.count = 2;
	atpx_arg.pointer = &atpx_arg_elements[0];

	atpx_arg_elements[0].type = ACPI_TYPE_INTEGER;
	atpx_arg_elements[0].integer.value = function;

	if (params) {
	atpx_arg_elements[1].type = ACPI_TYPE_BUFFER;
	atpx_arg_elements[1].buffer.length = params->length;
	atpx_arg_elements[1].buffer.pointer = params->pointer;
	} else {
	/* We need a second fake parameter */
	atpx_arg_elements[1].type = ACPI_TYPE_INTEGER;
	atpx_arg_elements[1].integer.value = 0;
	}

	status = acpi_evaluate_object(handle, NULL, &atpx_arg, &buffer);

	/* Fail only if calling the method fails and ATPX is supported */
	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
	printk("failed to evaluate ATPX got %s\n",
	acpi_format_exception(status));
	kfree(buffer.pointer);
	return NULL;
	}

	return buffer.pointer;
	}

	/**
	* radeon_atpx_parse_functions - parse supported functions
	*
	* @f: supported functions struct
	* @mask: supported functions mask from ATPX
	*
	* Use the supported functions mask from ATPX function
	* ATPX_FUNCTION_VERIFY_INTERFACE to determine what functions
	* are supported (all asics).
	*/
	static void radeon_atpx_parse_functions(struct radeon_atpx_functions *f, u32 mask)
	{
	f->px_params = mask & ATPX_GET_PX_PARAMETERS_SUPPORTED;
	f->power_cntl = mask & ATPX_POWER_CONTROL_SUPPORTED;
	f->disp_mux_cntl = mask & ATPX_DISPLAY_MUX_CONTROL_SUPPORTED;
	f->i2c_mux_cntl = mask & ATPX_I2C_MUX_CONTROL_SUPPORTED;
	f->switch_start = mask & ATPX_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION_SUPPORTED;
	f->switch_end = mask & ATPX_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION_SUPPORTED;
	f->disp_connectors_mapping = mask & ATPX_GET_DISPLAY_CONNECTORS_MAPPING_SUPPORTED;
	f->disp_detetion_ports = mask & ATPX_GET_DISPLAY_DETECTION_PORTS_SUPPORTED;
	}

	/**
	* radeon_atpx_validate_functions - validate ATPX functions
	*
	* @atpx: radeon atpx struct
	*
	* Validate that required functions are enabled (all asics).
	* returns 0 on success, error on failure.
	*/
	static int radeon_atpx_validate(struct radeon_atpx *atpx)
	{
	/* make sure required functions are enabled */
	/* dGPU power control is required */
	atpx->functions.power_cntl = true;

	if (atpx->functions.px_params) {
	union acpi_object *info;
	struct atpx_px_params output;
	size_t size;
	u32 valid_bits;

	info = radeon_atpx_call(atpx->handle, ATPX_FUNCTION_GET_PX_PARAMETERS, NULL);
	if (!info)
	return -EIO;

	memset(&output, 0, sizeof(output));

	size = (u16 ) info->buffer.pointer;
	if (size < 10) {
	printk("ATPX buffer is too small: %zu\n", size);
	kfree(info);
	return -EINVAL;
	}
	size = min(sizeof(output), size);

	memcpy(&output, info->buffer.pointer, size);

	valid_bits = output.flags & output.valid_flags;
	/* if separate mux flag is set, mux controls are required */
	if (valid_bits & ATPX_SEPARATE_MUX_FOR_I2C) {
	atpx->functions.i2c_mux_cntl = true;
	atpx->functions.disp_mux_cntl = true;
	}
	/* if any outputs are muxed, mux controls are required */
	if (valid_bits & (ATPX_CRT1_RGB_SIGNAL_MUXED \|
	ATPX_TV_SIGNAL_MUXED \|
	ATPX_DFP_SIGNAL_MUXED))
	atpx->functions.disp_mux_cntl = true;

	kfree(info);
	}
	return 0;
	}

	/**
	* radeon_atpx_verify_interface - verify ATPX
	*
	* @atpx: radeon atpx struct
	*
	* Execute the ATPX_FUNCTION_VERIFY_INTERFACE ATPX function
	* to initialize ATPX and determine what features are supported
	* (all asics).
	* returns 0 on success, error on failure.
	*/
	static int radeon_atpx_verify_interface(struct radeon_atpx *atpx)
	{
	union acpi_object *info;
	struct atpx_verify_interface output;
	size_t size;
	int err = 0;

	info = radeon_atpx_call(atpx->handle, ATPX_FUNCTION_VERIFY_INTERFACE, NULL);
	if (!info)
	return -EIO;

	memset(&output, 0, sizeof(output));

	size = (u16 ) info->buffer.pointer;
	if (size < 8) {
	printk("ATPX buffer is too small: %zu\n", size);
	err = -EINVAL;
	goto out;
	}
	size = min(sizeof(output), size);

	memcpy(&output, info->buffer.pointer, size);

	/* TODO: check version? */
	printk("ATPX version %u, functions 0x%08x\n",
	output.version, output.function_bits);

	radeon_atpx_parse_functions(&atpx->functions, output.function_bits);

	out:
	kfree(info);
	return err;
	}

	/**
	* radeon_atpx_set_discrete_state - power up/down discrete GPU
	*
	* @atpx: atpx info struct
	* @state: discrete GPU state (0 = power down, 1 = power up)
	*
	* Execute the ATPX_FUNCTION_POWER_CONTROL ATPX function to
	* power down/up the discrete GPU (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_set_discrete_state(struct radeon_atpx *atpx, u8 state)
	{
	struct acpi_buffer params;
	union acpi_object *info;
	struct atpx_power_control input;

	if (atpx->functions.power_cntl) {
	input.size = 3;
	input.dgpu_state = state;
	params.length = input.size;
	params.pointer = &input;
	info = radeon_atpx_call(atpx->handle,
	ATPX_FUNCTION_POWER_CONTROL,
	&params);
	if (!info)
	return -EIO;
	kfree(info);
	}
	return 0;
	}

	/**
	* radeon_atpx_switch_disp_mux - switch display mux
	*
	* @atpx: atpx info struct
	* @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
	*
	* Execute the ATPX_FUNCTION_DISPLAY_MUX_CONTROL ATPX function to
	* switch the display mux between the discrete GPU and integrated GPU
	* (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_switch_disp_mux(struct radeon_atpx *atpx, u16 mux_id)
	{
	struct acpi_buffer params;
	union acpi_object *info;
	struct atpx_mux input;

	if (atpx->functions.disp_mux_cntl) {
	input.size = 4;
	input.mux = mux_id;
	params.length = input.size;
	params.pointer = &input;
	info = radeon_atpx_call(atpx->handle,
	ATPX_FUNCTION_DISPLAY_MUX_CONTROL,
	&params);
	if (!info)
	return -EIO;
	kfree(info);
	}
	return 0;
	}

	/**
	* radeon_atpx_switch_i2c_mux - switch i2c/hpd mux
	*
	* @atpx: atpx info struct
	* @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
	*
	* Execute the ATPX_FUNCTION_I2C_MUX_CONTROL ATPX function to
	* switch the i2c/hpd mux between the discrete GPU and integrated GPU
	* (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_switch_i2c_mux(struct radeon_atpx *atpx, u16 mux_id)
	{
	struct acpi_buffer params;
	union acpi_object *info;
	struct atpx_mux input;

	if (atpx->functions.i2c_mux_cntl) {
	input.size = 4;
	input.mux = mux_id;
	params.length = input.size;
	params.pointer = &input;
	info = radeon_atpx_call(atpx->handle,
	ATPX_FUNCTION_I2C_MUX_CONTROL,
	&params);
	if (!info)
	return -EIO;
	kfree(info);
	}
	return 0;
	}

	/**
	* radeon_atpx_switch_start - notify the sbios of a GPU switch
	*
	* @atpx: atpx info struct
	* @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
	*
	* Execute the ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION ATPX
	* function to notify the sbios that a switch between the discrete GPU and
	* integrated GPU has begun (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_switch_start(struct radeon_atpx *atpx, u16 mux_id)
	{
	struct acpi_buffer params;
	union acpi_object *info;
	struct atpx_mux input;

	if (atpx->functions.switch_start) {
	input.size = 4;
	input.mux = mux_id;
	params.length = input.size;
	params.pointer = &input;
	info = radeon_atpx_call(atpx->handle,
	ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION,
	&params);
	if (!info)
	return -EIO;
	kfree(info);
	}
	return 0;
	}

	/**
	* radeon_atpx_switch_end - notify the sbios of a GPU switch
	*
	* @atpx: atpx info struct
	* @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
	*
	* Execute the ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION ATPX
	* function to notify the sbios that a switch between the discrete GPU and
	* integrated GPU has ended (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_switch_end(struct radeon_atpx *atpx, u16 mux_id)
	{
	struct acpi_buffer params;
	union acpi_object *info;
	struct atpx_mux input;

	if (atpx->functions.switch_end) {
	input.size = 4;
	input.mux = mux_id;
	params.length = input.size;
	params.pointer = &input;
	info = radeon_atpx_call(atpx->handle,
	ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION,
	&params);
	if (!info)
	return -EIO;
	kfree(info);
	}
	return 0;
	}

	/**
	* radeon_atpx_switchto - switch to the requested GPU
	*
	* @id: GPU to switch to
	*
	* Execute the necessary ATPX functions to switch between the discrete GPU and
	* integrated GPU (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_switchto(enum vga_switcheroo_client_id id)
	{
	u16 gpu_id;

	if (id == VGA_SWITCHEROO_IGD)
	gpu_id = ATPX_INTEGRATED_GPU;
	else
	gpu_id = ATPX_DISCRETE_GPU;

	radeon_atpx_switch_start(&radeon_atpx_priv.atpx, gpu_id);
	radeon_atpx_switch_disp_mux(&radeon_atpx_priv.atpx, gpu_id);
	radeon_atpx_switch_i2c_mux(&radeon_atpx_priv.atpx, gpu_id);
	radeon_atpx_switch_end(&radeon_atpx_priv.atpx, gpu_id);

	return 0;
	}

	/**
	* radeon_atpx_power_state - power down/up the requested GPU
	*
	* @id: GPU to power down/up
	* @state: requested power state (0 = off, 1 = on)
	*
	* Execute the necessary ATPX function to power down/up the discrete GPU
	* (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_power_state(enum vga_switcheroo_client_id id,
	enum vga_switcheroo_state state)
	{
	/* on w500 ACPI can't change intel gpu state */
	if (id == VGA_SWITCHEROO_IGD)
	return 0;

	radeon_atpx_set_discrete_state(&radeon_atpx_priv.atpx, state);
	return 0;
	}

	/**
	* radeon_atpx_pci_probe_handle - look up the ATPX handle
	*
	* @pdev: pci device
	*
	* Look up the ATPX handles (all asics).
	* Returns true if the handles are found, false if not.
	*/
	static bool radeon_atpx_pci_probe_handle(struct pci_dev *pdev)
	{
	acpi_handle dhandle, atpx_handle;
	acpi_status status;

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

	status = acpi_get_handle(dhandle, "ATPX", &atpx_handle);
	if (ACPI_FAILURE(status)) {
	radeon_atpx_priv.other_handle = dhandle;
	return false;
	}
	radeon_atpx_priv.dhandle = dhandle;
	radeon_atpx_priv.atpx.handle = atpx_handle;
	return true;
	}

	/**
	* radeon_atpx_init - verify the ATPX interface
	*
	* Verify the ATPX interface (all asics).
	* Returns 0 on success, error on failure.
	*/
	static int radeon_atpx_init(void)
	{
	int r;

	/* set up the ATPX handle */
	r = radeon_atpx_verify_interface(&radeon_atpx_priv.atpx);
	if (r)
	return r;

	/* validate the atpx setup */
	r = radeon_atpx_validate(&radeon_atpx_priv.atpx);
	if (r)
	return r;

	return 0;
	}

	/**
	* radeon_atpx_get_client_id - get the client id
	*
	* @pdev: pci device
	*
	* look up whether we are the integrated or discrete GPU (all asics).
	* Returns the client id.
	*/
	static int radeon_atpx_get_client_id(struct pci_dev *pdev)
	{
	if (radeon_atpx_priv.dhandle == ACPI_HANDLE(&pdev->dev))
	return VGA_SWITCHEROO_IGD;
	else
	return VGA_SWITCHEROO_DIS;
	}

	static struct vga_switcheroo_handler radeon_atpx_handler = {
	.switchto = radeon_atpx_switchto,
	.power_state = radeon_atpx_power_state,
	.init = radeon_atpx_init,
	.get_client_id = radeon_atpx_get_client_id,
	};

	/**
	* radeon_atpx_detect - detect whether we have PX
	*
	* Check if we have a PX system (all asics).
	* Returns true if we have a PX system, false if not.
	*/
	static bool radeon_atpx_detect(void)
	{
	char acpi_method_name[255] = { 0 };
	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
	struct pci_dev *pdev = NULL;
	bool has_atpx = false;
	int vga_count = 0;

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

	has_atpx \|= (radeon_atpx_pci_probe_handle(pdev) == true);
	}

	if (has_atpx && vga_count == 2) {
	acpi_get_name(radeon_atpx_priv.atpx.handle, ACPI_FULL_PATHNAME, &buffer);
	printk(KERN_INFO "VGA switcheroo: detected switching method %s handle\n",
	acpi_method_name);
	radeon_atpx_priv.atpx_detected = true;
	/*
	* On some systems hotplug events are generated for the device
	* being switched off when ATPX is executed. They cause ACPI
	* hotplug to trigger and attempt to remove the device from
	* the system, which causes it to break down. Prevent that from
	* happening by setting the no_hotplug flag for the involved
	* ACPI device objects.
	*/
	acpi_bus_no_hotplug(radeon_atpx_priv.dhandle);
	acpi_bus_no_hotplug(radeon_atpx_priv.other_handle);
	return true;
	}
	return false;
	}

	/**
	* radeon_register_atpx_handler - register with vga_switcheroo
	*
	* Register the PX callbacks with vga_switcheroo (all asics).
	*/
	void radeon_register_atpx_handler(void)
	{
	bool r;

	/* detect if we have any ATPX + 2 VGA in the system */
	r = radeon_atpx_detect();
	if (!r)
	return;

	vga_switcheroo_register_handler(&radeon_atpx_handler);
	}

	/**
	* radeon_unregister_atpx_handler - unregister with vga_switcheroo
	*
	* Unregister the PX callbacks with vga_switcheroo (all asics).
	*/
	void radeon_unregister_atpx_handler(void)
	{
	vga_switcheroo_unregister_handler();
	}