drivers/gpu/vga/vga_switcheroo.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2010 Red Hat Inc.
  * Author : Dave Airlie <airlied@redhat.com>
  *
  *
  * Licensed under GPLv2
  *
  * vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs

  Switcher interface - methods require for ATPX and DCM
  - switchto - this throws the output MUX switch
  - discrete_set_power - sets the power state for the discrete card

  GPU driver interface
  - set_gpu_state - this should do the equiv of s/r for the card
 		  - this should *not* set the discrete power state
  - switch_check  - check if the device is in a position to switch now
  */

 #include <linux/module.h>
 #include <linux/dmi.h>
 #include <linux/seq_file.h>
 #include <linux/uaccess.h>
 #include <linux/fs.h>
 #include <linux/debugfs.h>
 #include <linux/fb.h>

 #include <linux/pci.h>
 #include <linux/vga_switcheroo.h>

 #include <linux/vgaarb.h>

 struct vga_switcheroo_client {
 	struct pci_dev *pdev;
 	struct fb_info *fb_info;
 	int pwr_state;
 	const struct vga_switcheroo_client_ops *ops;
 	int id;
 	bool active;
 	struct list_head list;
 };

 static DEFINE_MUTEX(vgasr_mutex);

 struct vgasr_priv {

 	bool active;
 	bool delayed_switch_active;
 	enum vga_switcheroo_client_id delayed_client_id;

 	struct dentry *debugfs_root;
 	struct dentry *switch_file;

 	int registered_clients;
 	struct list_head clients;

 	struct vga_switcheroo_handler *handler;
 };

 #define ID_BIT_AUDIO		0x100
 #define client_is_audio(c)	((c)->id & ID_BIT_AUDIO)
 #define client_is_vga(c)	((c)->id == -1 || !client_is_audio(c))
 #define client_id(c)		((c)->id & ~ID_BIT_AUDIO)

 static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
 static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);

 /* only one switcheroo per system */
 static struct vgasr_priv vgasr_priv = {
 	.clients = LIST_HEAD_INIT(vgasr_priv.clients),
 };

 static bool vga_switcheroo_ready(void)
 {
 	/* we're ready if we get two clients + handler */
 	return !vgasr_priv.active &&
 	       vgasr_priv.registered_clients == 2 && vgasr_priv.handler;
 }

 static void vga_switcheroo_enable(void)
 {
 	int ret;
 	struct vga_switcheroo_client *client;

 	/* call the handler to init */
 	if (vgasr_priv.handler->init)
 		vgasr_priv.handler->init();

 	list_for_each_entry(client, &vgasr_priv.clients, list) {
 		if (client->id != -1)
 			continue;
 		ret = vgasr_priv.handler->get_client_id(client->pdev);
 		if (ret < 0)
 			return;

 		client->id = ret;
 	}
 	vga_switcheroo_debugfs_init(&vgasr_priv);
 	vgasr_priv.active = true;
 }

 int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
 {
 	mutex_lock(&vgasr_mutex);
 	if (vgasr_priv.handler) {
 		mutex_unlock(&vgasr_mutex);
 		return -EINVAL;
 	}

 	vgasr_priv.handler = handler;
 	if (vga_switcheroo_ready()) {
 		printk(KERN_INFO "vga_switcheroo: enabled\n");
 		vga_switcheroo_enable();
 	}
 	mutex_unlock(&vgasr_mutex);
 	return 0;
 }
 EXPORT_SYMBOL(vga_switcheroo_register_handler);

 void vga_switcheroo_unregister_handler(void)
 {
 	mutex_lock(&vgasr_mutex);
 	vgasr_priv.handler = NULL;
 	if (vgasr_priv.active) {
 		pr_info("vga_switcheroo: disabled\n");
 		vga_switcheroo_debugfs_fini(&vgasr_priv);
 		vgasr_priv.active = false;
 	}
 	mutex_unlock(&vgasr_mutex);
 }
 EXPORT_SYMBOL(vga_switcheroo_unregister_handler);

 static int register_client(struct pci_dev *pdev,
 			   const struct vga_switcheroo_client_ops *ops,
 			   int id, bool active)
 {
 	struct vga_switcheroo_client *client;

 	client = kzalloc(sizeof(*client), GFP_KERNEL);
 	if (!client)
 		return -ENOMEM;

 	client->pwr_state = VGA_SWITCHEROO_ON;
 	client->pdev = pdev;
 	client->ops = ops;
 	client->id = id;
 	client->active = active;

 	mutex_lock(&vgasr_mutex);
 	list_add_tail(&client->list, &vgasr_priv.clients);
 	if (client_is_vga(client))
 		vgasr_priv.registered_clients++;

 	if (vga_switcheroo_ready()) {
 		printk(KERN_INFO "vga_switcheroo: enabled\n");
 		vga_switcheroo_enable();
 	}
 	mutex_unlock(&vgasr_mutex);
 	return 0;
 }

 int vga_switcheroo_register_client(struct pci_dev *pdev,
 				   const struct vga_switcheroo_client_ops *ops)
 {
 	return register_client(pdev, ops, -1,
 			       pdev == vga_default_device());
 }
 EXPORT_SYMBOL(vga_switcheroo_register_client);

 int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
 					 const struct vga_switcheroo_client_ops *ops,
 					 int id, bool active)
 {
 	return register_client(pdev, ops, id | ID_BIT_AUDIO, active);
 }
 EXPORT_SYMBOL(vga_switcheroo_register_audio_client);

 static struct vga_switcheroo_client *
 find_client_from_pci(struct list_head *head, struct pci_dev *pdev)
 {
 	struct vga_switcheroo_client *client;
 	list_for_each_entry(client, head, list)
 		if (client->pdev == pdev)
 			return client;
 	return NULL;
 }

 static struct vga_switcheroo_client *
 find_client_from_id(struct list_head *head, int client_id)
 {
 	struct vga_switcheroo_client *client;
 	list_for_each_entry(client, head, list)
 		if (client->id == client_id)
 			return client;
 	return NULL;
 }

 static struct vga_switcheroo_client *
 find_active_client(struct list_head *head)
 {
 	struct vga_switcheroo_client *client;
 	list_for_each_entry(client, head, list)
 		if (client->active && client_is_vga(client))
 			return client;
 	return NULL;
 }

 int vga_switcheroo_get_client_state(struct pci_dev *pdev)
 {
 	struct vga_switcheroo_client *client;

 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
 	if (!client)
 		return VGA_SWITCHEROO_NOT_FOUND;
 	if (!vgasr_priv.active)
 		return VGA_SWITCHEROO_INIT;
 	return client->pwr_state;
 }
 EXPORT_SYMBOL(vga_switcheroo_get_client_state);

 void vga_switcheroo_unregister_client(struct pci_dev *pdev)
 {
 	struct vga_switcheroo_client *client;

 	mutex_lock(&vgasr_mutex);
 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
 	if (client) {
 		if (client_is_vga(client))
 			vgasr_priv.registered_clients--;
 		list_del(&client->list);
 		kfree(client);
 	}
 	if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
 		printk(KERN_INFO "vga_switcheroo: disabled\n");
 		vga_switcheroo_debugfs_fini(&vgasr_priv);
 		vgasr_priv.active = false;
 	}
 	mutex_unlock(&vgasr_mutex);
 }
 EXPORT_SYMBOL(vga_switcheroo_unregister_client);

 void vga_switcheroo_client_fb_set(struct pci_dev *pdev,
 				 struct fb_info *info)
 {
 	struct vga_switcheroo_client *client;

 	mutex_lock(&vgasr_mutex);
 	client = find_client_from_pci(&vgasr_priv.clients, pdev);
 	if (client)
 		client->fb_info = info;
 	mutex_unlock(&vgasr_mutex);
 }
 EXPORT_SYMBOL(vga_switcheroo_client_fb_set);

 static int vga_switcheroo_show(struct seq_file *m, void *v)
 {
 	struct vga_switcheroo_client *client;
 	int i = 0;
 	mutex_lock(&vgasr_mutex);
 	list_for_each_entry(client, &vgasr_priv.clients, list) {
 		seq_printf(m, "%d:%s%s:%c:%s:%s\n", i,
 			   client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" : "IGD",
 			   client_is_vga(client) ? "" : "-Audio",
 			   client->active ? '+' : ' ',
 			   client->pwr_state ? "Pwr" : "Off",
 			   pci_name(client->pdev));
 		i++;
 	}
 	mutex_unlock(&vgasr_mutex);
 	return 0;
 }

 static int vga_switcheroo_debugfs_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, vga_switcheroo_show, NULL);
 }

 static int vga_switchon(struct vga_switcheroo_client *client)
 {
 	if (vgasr_priv.handler->power_state)
 		vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_ON);
 	/* call the driver callback to turn on device */
 	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_ON);
 	client->pwr_state = VGA_SWITCHEROO_ON;
 	return 0;
 }

 static int vga_switchoff(struct vga_switcheroo_client *client)
 {
 	/* call the driver callback to turn off device */
 	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_OFF);
 	if (vgasr_priv.handler->power_state)
 		vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_OFF);
 	client->pwr_state = VGA_SWITCHEROO_OFF;
 	return 0;
 }

 static void set_audio_state(int id, int state)
 {
 	struct vga_switcheroo_client *client;

 	client = find_client_from_id(&vgasr_priv.clients, id | ID_BIT_AUDIO);
 	if (client && client->pwr_state != state) {
 		client->ops->set_gpu_state(client->pdev, state);
 		client->pwr_state = state;
 	}
 }

 /* stage one happens before delay */
 static int vga_switchto_stage1(struct vga_switcheroo_client *new_client)
 {
 	struct vga_switcheroo_client *active;

 	active = find_active_client(&vgasr_priv.clients);
 	if (!active)
 		return 0;

 	if (new_client->pwr_state == VGA_SWITCHEROO_OFF)
 		vga_switchon(new_client);

 	vga_set_default_device(new_client->pdev);
 	return 0;
 }

 /* post delay */
 static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
 {
 	int ret;
 	struct vga_switcheroo_client *active;

 	active = find_active_client(&vgasr_priv.clients);
 	if (!active)
 		return 0;

 	active->active = false;

 	set_audio_state(active->id, VGA_SWITCHEROO_OFF);

 	if (new_client->fb_info) {
 		struct fb_event event;
 		event.info = new_client->fb_info;
 		fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
 	}

 	ret = vgasr_priv.handler->switchto(new_client->id);
 	if (ret)
 		return ret;

 	if (new_client->ops->reprobe)
 		new_client->ops->reprobe(new_client->pdev);

 	if (active->pwr_state == VGA_SWITCHEROO_ON)
 		vga_switchoff(active);

 	set_audio_state(new_client->id, VGA_SWITCHEROO_ON);

 	new_client->active = true;
 	return 0;
 }

 static bool check_can_switch(void)
 {
 	struct vga_switcheroo_client *client;

 	list_for_each_entry(client, &vgasr_priv.clients, list) {
 		if (!client->ops->can_switch(client->pdev)) {
 			printk(KERN_ERR "vga_switcheroo: client %x refused switch\n", client->id);
 			return false;
 		}
 	}
 	return true;
 }

 static ssize_t
 vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf,
 			     size_t cnt, loff_t *ppos)
 {
 	char usercmd[64];
 	const char *pdev_name;
 	int ret;
 	bool delay = false, can_switch;
 	bool just_mux = false;
 	int client_id = -1;
 	struct vga_switcheroo_client *client = NULL;

 	if (cnt > 63)
 		cnt = 63;

 	if (copy_from_user(usercmd, ubuf, cnt))
 		return -EFAULT;

 	mutex_lock(&vgasr_mutex);

 	if (!vgasr_priv.active) {
 		cnt = -EINVAL;
 		goto out;
 	}

 	/* pwr off the device not in use */
 	if (strncmp(usercmd, "OFF", 3) == 0) {
 		list_for_each_entry(client, &vgasr_priv.clients, list) {
 			if (client->active || client_is_audio(client))
 				continue;
 			set_audio_state(client->id, VGA_SWITCHEROO_OFF);
 			if (client->pwr_state == VGA_SWITCHEROO_ON)
 				vga_switchoff(client);
 		}
 		goto out;
 	}
 	/* pwr on the device not in use */
 	if (strncmp(usercmd, "ON", 2) == 0) {
 		list_for_each_entry(client, &vgasr_priv.clients, list) {
 			if (client->active || client_is_audio(client))
 				continue;
 			if (client->pwr_state == VGA_SWITCHEROO_OFF)
 				vga_switchon(client);
 			set_audio_state(client->id, VGA_SWITCHEROO_ON);
 		}
 		goto out;
 	}

 	/* request a delayed switch - test can we switch now */
 	if (strncmp(usercmd, "DIGD", 4) == 0) {
 		client_id = VGA_SWITCHEROO_IGD;
 		delay = true;
 	}

 	if (strncmp(usercmd, "DDIS", 4) == 0) {
 		client_id = VGA_SWITCHEROO_DIS;
 		delay = true;
 	}

 	if (strncmp(usercmd, "IGD", 3) == 0)
 		client_id = VGA_SWITCHEROO_IGD;

 	if (strncmp(usercmd, "DIS", 3) == 0)
 		client_id = VGA_SWITCHEROO_DIS;

 	if (strncmp(usercmd, "MIGD", 4) == 0) {
 		just_mux = true;
 		client_id = VGA_SWITCHEROO_IGD;
 	}
 	if (strncmp(usercmd, "MDIS", 4) == 0) {
 		just_mux = true;
 		client_id = VGA_SWITCHEROO_DIS;
 	}

 	if (client_id == -1)
 		goto out;
 	client = find_client_from_id(&vgasr_priv.clients, client_id);
 	if (!client)
 		goto out;

 	vgasr_priv.delayed_switch_active = false;

 	if (just_mux) {
 		ret = vgasr_priv.handler->switchto(client_id);
 		goto out;
 	}

 	if (client->active)
 		goto out;

 	/* okay we want a switch - test if devices are willing to switch */
 	can_switch = check_can_switch();

 	if (can_switch == false && delay == false)
 		goto out;

 	if (can_switch) {
 		pdev_name = pci_name(client->pdev);
 		ret = vga_switchto_stage1(client);
 		if (ret)
 			printk(KERN_ERR "vga_switcheroo: switching failed stage 1 %d\n", ret);

 		ret = vga_switchto_stage2(client);
 		if (ret)
 			printk(KERN_ERR "vga_switcheroo: switching failed stage 2 %d\n", ret);

 	} else {
 		printk(KERN_INFO "vga_switcheroo: setting delayed switch to client %d\n", client->id);
 		vgasr_priv.delayed_switch_active = true;
 		vgasr_priv.delayed_client_id = client_id;

 		ret = vga_switchto_stage1(client);
 		if (ret)
 			printk(KERN_ERR "vga_switcheroo: delayed switching stage 1 failed %d\n", ret);
 	}

 out:
 	mutex_unlock(&vgasr_mutex);
 	return cnt;
 }

 static const struct file_operations vga_switcheroo_debugfs_fops = {
 	.owner = THIS_MODULE,
 	.open = vga_switcheroo_debugfs_open,
 	.write = vga_switcheroo_debugfs_write,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = single_release,
 };

 static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv)
 {
 	if (priv->switch_file) {
 		debugfs_remove(priv->switch_file);
 		priv->switch_file = NULL;
 	}
 	if (priv->debugfs_root) {
 		debugfs_remove(priv->debugfs_root);
 		priv->debugfs_root = NULL;
 	}
 }

 static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv)
 {
 	/* already initialised */
 	if (priv->debugfs_root)
 		return 0;
 	priv->debugfs_root = debugfs_create_dir("vgaswitcheroo", NULL);

 	if (!priv->debugfs_root) {
 		printk(KERN_ERR "vga_switcheroo: Cannot create /sys/kernel/debug/vgaswitcheroo\n");
 		goto fail;
 	}

 	priv->switch_file = debugfs_create_file("switch", 0644,
 						priv->debugfs_root, NULL, &vga_switcheroo_debugfs_fops);
 	if (!priv->switch_file) {
 		printk(KERN_ERR "vga_switcheroo: cannot create /sys/kernel/debug/vgaswitcheroo/switch\n");
 		goto fail;
 	}
 	return 0;
 fail:
 	vga_switcheroo_debugfs_fini(priv);
 	return -1;
 }

 int vga_switcheroo_process_delayed_switch(void)
 {
 	struct vga_switcheroo_client *client;
 	const char *pdev_name;
 	int ret;
 	int err = -EINVAL;

 	mutex_lock(&vgasr_mutex);
 	if (!vgasr_priv.delayed_switch_active)
 		goto err;

 	printk(KERN_INFO "vga_switcheroo: processing delayed switch to %d\n", vgasr_priv.delayed_client_id);

 	client = find_client_from_id(&vgasr_priv.clients,
 				     vgasr_priv.delayed_client_id);
 	if (!client || !check_can_switch())
 		goto err;

 	pdev_name = pci_name(client->pdev);
 	ret = vga_switchto_stage2(client);
 	if (ret)
 		printk(KERN_ERR "vga_switcheroo: delayed switching failed stage 2 %d\n", ret);

 	vgasr_priv.delayed_switch_active = false;
 	err = 0;
 err:
 	mutex_unlock(&vgasr_mutex);
 	return err;
 }
 EXPORT_SYMBOL(vga_switcheroo_process_delayed_switch);
	/*
	* Copyright (c) 2010 Red Hat Inc.
	* Author : Dave Airlie <airlied@redhat.com>
	*
	*
	* Licensed under GPLv2
	*
	* vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs

	Switcher interface - methods require for ATPX and DCM
	- switchto - this throws the output MUX switch
	- discrete_set_power - sets the power state for the discrete card

	GPU driver interface
	- set_gpu_state - this should do the equiv of s/r for the card
	- this should not set the discrete power state
	- switch_check - check if the device is in a position to switch now
	*/

	#include <linux/module.h>
	#include <linux/dmi.h>
	#include <linux/seq_file.h>
	#include <linux/uaccess.h>
	#include <linux/fs.h>
	#include <linux/debugfs.h>
	#include <linux/fb.h>

	#include <linux/pci.h>
	#include <linux/vga_switcheroo.h>

	#include <linux/vgaarb.h>

	struct vga_switcheroo_client {
	struct pci_dev *pdev;
	struct fb_info *fb_info;
	int pwr_state;
	const struct vga_switcheroo_client_ops *ops;
	int id;
	bool active;
	struct list_head list;
	};

	static DEFINE_MUTEX(vgasr_mutex);

	struct vgasr_priv {

	bool active;
	bool delayed_switch_active;
	enum vga_switcheroo_client_id delayed_client_id;

	struct dentry *debugfs_root;
	struct dentry *switch_file;

	int registered_clients;
	struct list_head clients;

	struct vga_switcheroo_handler *handler;
	};

	#define ID_BIT_AUDIO 0x100
	#define client_is_audio(c) ((c)->id & ID_BIT_AUDIO)
	#define client_is_vga(c) ((c)->id == -1 \|\| !client_is_audio(c))
	#define client_id(c) ((c)->id & ~ID_BIT_AUDIO)

	static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
	static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);

	/* only one switcheroo per system */
	static struct vgasr_priv vgasr_priv = {
	.clients = LIST_HEAD_INIT(vgasr_priv.clients),
	};

	static bool vga_switcheroo_ready(void)
	{
	/* we're ready if we get two clients + handler */
	return !vgasr_priv.active &&
	vgasr_priv.registered_clients == 2 && vgasr_priv.handler;
	}

	static void vga_switcheroo_enable(void)
	{
	int ret;
	struct vga_switcheroo_client *client;

	/* call the handler to init */
	if (vgasr_priv.handler->init)
	vgasr_priv.handler->init();

	list_for_each_entry(client, &vgasr_priv.clients, list) {
	if (client->id != -1)
	continue;
	ret = vgasr_priv.handler->get_client_id(client->pdev);
	if (ret < 0)
	return;

	client->id = ret;
	}
	vga_switcheroo_debugfs_init(&vgasr_priv);
	vgasr_priv.active = true;
	}

	int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
	{
	mutex_lock(&vgasr_mutex);
	if (vgasr_priv.handler) {
	mutex_unlock(&vgasr_mutex);
	return -EINVAL;
	}

	vgasr_priv.handler = handler;
	if (vga_switcheroo_ready()) {
	printk(KERN_INFO "vga_switcheroo: enabled\n");
	vga_switcheroo_enable();
	}
	mutex_unlock(&vgasr_mutex);
	return 0;
	}
	EXPORT_SYMBOL(vga_switcheroo_register_handler);

	void vga_switcheroo_unregister_handler(void)
	{
	mutex_lock(&vgasr_mutex);
	vgasr_priv.handler = NULL;
	if (vgasr_priv.active) {
	pr_info("vga_switcheroo: disabled\n");
	vga_switcheroo_debugfs_fini(&vgasr_priv);
	vgasr_priv.active = false;
	}
	mutex_unlock(&vgasr_mutex);
	}
	EXPORT_SYMBOL(vga_switcheroo_unregister_handler);

	static int register_client(struct pci_dev *pdev,
	const struct vga_switcheroo_client_ops *ops,
	int id, bool active)
	{
	struct vga_switcheroo_client *client;

	client = kzalloc(sizeof(*client), GFP_KERNEL);
	if (!client)
	return -ENOMEM;

	client->pwr_state = VGA_SWITCHEROO_ON;
	client->pdev = pdev;
	client->ops = ops;
	client->id = id;
	client->active = active;

	mutex_lock(&vgasr_mutex);
	list_add_tail(&client->list, &vgasr_priv.clients);
	if (client_is_vga(client))
	vgasr_priv.registered_clients++;

	if (vga_switcheroo_ready()) {
	printk(KERN_INFO "vga_switcheroo: enabled\n");
	vga_switcheroo_enable();
	}
	mutex_unlock(&vgasr_mutex);
	return 0;
	}

	int vga_switcheroo_register_client(struct pci_dev *pdev,
	const struct vga_switcheroo_client_ops *ops)
	{
	return register_client(pdev, ops, -1,
	pdev == vga_default_device());
	}
	EXPORT_SYMBOL(vga_switcheroo_register_client);

	int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
	const struct vga_switcheroo_client_ops *ops,
	int id, bool active)
	{
	return register_client(pdev, ops, id \| ID_BIT_AUDIO, active);
	}
	EXPORT_SYMBOL(vga_switcheroo_register_audio_client);

	static struct vga_switcheroo_client *
	find_client_from_pci(struct list_head head, struct pci_dev pdev)
	{
	struct vga_switcheroo_client *client;
	list_for_each_entry(client, head, list)
	if (client->pdev == pdev)
	return client;
	return NULL;
	}

	static struct vga_switcheroo_client *
	find_client_from_id(struct list_head *head, int client_id)
	{
	struct vga_switcheroo_client *client;
	list_for_each_entry(client, head, list)
	if (client->id == client_id)
	return client;
	return NULL;
	}

	static struct vga_switcheroo_client *
	find_active_client(struct list_head *head)
	{
	struct vga_switcheroo_client *client;
	list_for_each_entry(client, head, list)
	if (client->active && client_is_vga(client))
	return client;
	return NULL;
	}

	int vga_switcheroo_get_client_state(struct pci_dev *pdev)
	{
	struct vga_switcheroo_client *client;

	client = find_client_from_pci(&vgasr_priv.clients, pdev);
	if (!client)
	return VGA_SWITCHEROO_NOT_FOUND;
	if (!vgasr_priv.active)
	return VGA_SWITCHEROO_INIT;
	return client->pwr_state;
	}
	EXPORT_SYMBOL(vga_switcheroo_get_client_state);

	void vga_switcheroo_unregister_client(struct pci_dev *pdev)
	{
	struct vga_switcheroo_client *client;

	mutex_lock(&vgasr_mutex);
	client = find_client_from_pci(&vgasr_priv.clients, pdev);
	if (client) {
	if (client_is_vga(client))
	vgasr_priv.registered_clients--;
	list_del(&client->list);
	kfree(client);
	}
	if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
	printk(KERN_INFO "vga_switcheroo: disabled\n");
	vga_switcheroo_debugfs_fini(&vgasr_priv);
	vgasr_priv.active = false;
	}
	mutex_unlock(&vgasr_mutex);
	}
	EXPORT_SYMBOL(vga_switcheroo_unregister_client);

	void vga_switcheroo_client_fb_set(struct pci_dev *pdev,
	struct fb_info *info)
	{
	struct vga_switcheroo_client *client;

	mutex_lock(&vgasr_mutex);
	client = find_client_from_pci(&vgasr_priv.clients, pdev);
	if (client)
	client->fb_info = info;
	mutex_unlock(&vgasr_mutex);
	}
	EXPORT_SYMBOL(vga_switcheroo_client_fb_set);

	static int vga_switcheroo_show(struct seq_file m, void v)
	{
	struct vga_switcheroo_client *client;
	int i = 0;
	mutex_lock(&vgasr_mutex);
	list_for_each_entry(client, &vgasr_priv.clients, list) {
	seq_printf(m, "%d:%s%s:%c:%s:%s\n", i,
	client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" : "IGD",
	client_is_vga(client) ? "" : "-Audio",
	client->active ? '+' : ' ',
	client->pwr_state ? "Pwr" : "Off",
	pci_name(client->pdev));
	i++;
	}
	mutex_unlock(&vgasr_mutex);
	return 0;
	}

	static int vga_switcheroo_debugfs_open(struct inode inode, struct file file)
	{
	return single_open(file, vga_switcheroo_show, NULL);
	}

	static int vga_switchon(struct vga_switcheroo_client *client)
	{
	if (vgasr_priv.handler->power_state)
	vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_ON);
	/* call the driver callback to turn on device */
	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_ON);
	client->pwr_state = VGA_SWITCHEROO_ON;
	return 0;
	}

	static int vga_switchoff(struct vga_switcheroo_client *client)
	{
	/* call the driver callback to turn off device */
	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_OFF);
	if (vgasr_priv.handler->power_state)
	vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_OFF);
	client->pwr_state = VGA_SWITCHEROO_OFF;
	return 0;
	}

	static void set_audio_state(int id, int state)
	{
	struct vga_switcheroo_client *client;

	client = find_client_from_id(&vgasr_priv.clients, id \| ID_BIT_AUDIO);
	if (client && client->pwr_state != state) {
	client->ops->set_gpu_state(client->pdev, state);
	client->pwr_state = state;
	}
	}

	/* stage one happens before delay */
	static int vga_switchto_stage1(struct vga_switcheroo_client *new_client)
	{
	struct vga_switcheroo_client *active;

	active = find_active_client(&vgasr_priv.clients);
	if (!active)
	return 0;

	if (new_client->pwr_state == VGA_SWITCHEROO_OFF)
	vga_switchon(new_client);

	vga_set_default_device(new_client->pdev);
	return 0;
	}

	/* post delay */
	static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
	{
	int ret;
	struct vga_switcheroo_client *active;

	active = find_active_client(&vgasr_priv.clients);
	if (!active)
	return 0;

	active->active = false;

	set_audio_state(active->id, VGA_SWITCHEROO_OFF);

	if (new_client->fb_info) {
	struct fb_event event;
	event.info = new_client->fb_info;
	fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
	}

	ret = vgasr_priv.handler->switchto(new_client->id);
	if (ret)
	return ret;

	if (new_client->ops->reprobe)
	new_client->ops->reprobe(new_client->pdev);

	if (active->pwr_state == VGA_SWITCHEROO_ON)
	vga_switchoff(active);

	set_audio_state(new_client->id, VGA_SWITCHEROO_ON);

	new_client->active = true;
	return 0;
	}

	static bool check_can_switch(void)
	{
	struct vga_switcheroo_client *client;

	list_for_each_entry(client, &vgasr_priv.clients, list) {
	if (!client->ops->can_switch(client->pdev)) {
	printk(KERN_ERR "vga_switcheroo: client %x refused switch\n", client->id);
	return false;
	}
	}
	return true;
	}

	static ssize_t
	vga_switcheroo_debugfs_write(struct file filp, const char __user ubuf,
	size_t cnt, loff_t *ppos)
	{
	char usercmd[64];
	const char *pdev_name;
	int ret;
	bool delay = false, can_switch;
	bool just_mux = false;
	int client_id = -1;
	struct vga_switcheroo_client *client = NULL;

	if (cnt > 63)
	cnt = 63;

	if (copy_from_user(usercmd, ubuf, cnt))
	return -EFAULT;

	mutex_lock(&vgasr_mutex);

	if (!vgasr_priv.active) {
	cnt = -EINVAL;
	goto out;
	}

	/* pwr off the device not in use */
	if (strncmp(usercmd, "OFF", 3) == 0) {
	list_for_each_entry(client, &vgasr_priv.clients, list) {
	if (client->active \|\| client_is_audio(client))
	continue;
	set_audio_state(client->id, VGA_SWITCHEROO_OFF);
	if (client->pwr_state == VGA_SWITCHEROO_ON)
	vga_switchoff(client);
	}
	goto out;
	}
	/* pwr on the device not in use */
	if (strncmp(usercmd, "ON", 2) == 0) {
	list_for_each_entry(client, &vgasr_priv.clients, list) {
	if (client->active \|\| client_is_audio(client))
	continue;
	if (client->pwr_state == VGA_SWITCHEROO_OFF)
	vga_switchon(client);
	set_audio_state(client->id, VGA_SWITCHEROO_ON);
	}
	goto out;
	}

	/* request a delayed switch - test can we switch now */
	if (strncmp(usercmd, "DIGD", 4) == 0) {
	client_id = VGA_SWITCHEROO_IGD;
	delay = true;
	}

	if (strncmp(usercmd, "DDIS", 4) == 0) {
	client_id = VGA_SWITCHEROO_DIS;
	delay = true;
	}

	if (strncmp(usercmd, "IGD", 3) == 0)
	client_id = VGA_SWITCHEROO_IGD;

	if (strncmp(usercmd, "DIS", 3) == 0)
	client_id = VGA_SWITCHEROO_DIS;

	if (strncmp(usercmd, "MIGD", 4) == 0) {
	just_mux = true;
	client_id = VGA_SWITCHEROO_IGD;
	}
	if (strncmp(usercmd, "MDIS", 4) == 0) {
	just_mux = true;
	client_id = VGA_SWITCHEROO_DIS;
	}

	if (client_id == -1)
	goto out;
	client = find_client_from_id(&vgasr_priv.clients, client_id);
	if (!client)
	goto out;

	vgasr_priv.delayed_switch_active = false;

	if (just_mux) {
	ret = vgasr_priv.handler->switchto(client_id);
	goto out;
	}

	if (client->active)
	goto out;

	/* okay we want a switch - test if devices are willing to switch */
	can_switch = check_can_switch();

	if (can_switch == false && delay == false)
	goto out;

	if (can_switch) {
	pdev_name = pci_name(client->pdev);
	ret = vga_switchto_stage1(client);
	if (ret)
	printk(KERN_ERR "vga_switcheroo: switching failed stage 1 %d\n", ret);

	ret = vga_switchto_stage2(client);
	if (ret)
	printk(KERN_ERR "vga_switcheroo: switching failed stage 2 %d\n", ret);

	} else {
	printk(KERN_INFO "vga_switcheroo: setting delayed switch to client %d\n", client->id);
	vgasr_priv.delayed_switch_active = true;
	vgasr_priv.delayed_client_id = client_id;

	ret = vga_switchto_stage1(client);
	if (ret)
	printk(KERN_ERR "vga_switcheroo: delayed switching stage 1 failed %d\n", ret);
	}

	out:
	mutex_unlock(&vgasr_mutex);
	return cnt;
	}

	static const struct file_operations vga_switcheroo_debugfs_fops = {
	.owner = THIS_MODULE,
	.open = vga_switcheroo_debugfs_open,
	.write = vga_switcheroo_debugfs_write,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	};

	static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv)
	{
	if (priv->switch_file) {
	debugfs_remove(priv->switch_file);
	priv->switch_file = NULL;
	}
	if (priv->debugfs_root) {
	debugfs_remove(priv->debugfs_root);
	priv->debugfs_root = NULL;
	}
	}

	static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv)
	{
	/* already initialised */
	if (priv->debugfs_root)
	return 0;
	priv->debugfs_root = debugfs_create_dir("vgaswitcheroo", NULL);

	if (!priv->debugfs_root) {
	printk(KERN_ERR "vga_switcheroo: Cannot create /sys/kernel/debug/vgaswitcheroo\n");
	goto fail;
	}

	priv->switch_file = debugfs_create_file("switch", 0644,
	priv->debugfs_root, NULL, &vga_switcheroo_debugfs_fops);
	if (!priv->switch_file) {
	printk(KERN_ERR "vga_switcheroo: cannot create /sys/kernel/debug/vgaswitcheroo/switch\n");
	goto fail;
	}
	return 0;
	fail:
	vga_switcheroo_debugfs_fini(priv);
	return -1;
	}

	int vga_switcheroo_process_delayed_switch(void)
	{
	struct vga_switcheroo_client *client;
	const char *pdev_name;
	int ret;
	int err = -EINVAL;

	mutex_lock(&vgasr_mutex);
	if (!vgasr_priv.delayed_switch_active)
	goto err;

	printk(KERN_INFO "vga_switcheroo: processing delayed switch to %d\n", vgasr_priv.delayed_client_id);

	client = find_client_from_id(&vgasr_priv.clients,
	vgasr_priv.delayed_client_id);
	if (!client \|\| !check_can_switch())
	goto err;

	pdev_name = pci_name(client->pdev);
	ret = vga_switchto_stage2(client);
	if (ret)
	printk(KERN_ERR "vga_switcheroo: delayed switching failed stage 2 %d\n", ret);

	vgasr_priv.delayed_switch_active = false;
	err = 0;
	err:
	mutex_unlock(&vgasr_mutex);
	return err;
	}
	EXPORT_SYMBOL(vga_switcheroo_process_delayed_switch);