Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 2652 insertions, 0 deletions

diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
new file mode 100644
index 000000000..b677e5d52
--- /dev/null
+++ b/drivers/gpu/vga/Kconfig
@@ -0,0 +1,30 @@
+config VGA_ARB
+	bool "VGA Arbitration" if EXPERT
+	default y
+	depends on (PCI && !S390)
+	help
+	  Some "legacy" VGA devices implemented on PCI typically have the same
+	  hard-decoded addresses as they did on ISA. When multiple PCI devices
+	  are accessed at same time they need some kind of coordination. Please
+	  see Documentation/gpu/vgaarbiter.rst for more details. Select this to
+	  enable VGA arbiter.
+
+config VGA_ARB_MAX_GPUS
+	int "Maximum number of GPUs"
+	default 16
+	depends on VGA_ARB
+	help
+	  Reserves space in the kernel to maintain resource locking for
+	  multiple GPUS.  The overhead for each GPU is very small.
+
+config VGA_SWITCHEROO
+	bool "Laptop Hybrid Graphics - GPU switching support"
+	depends on X86
+	depends on ACPI
+	select VGA_ARB
+	help
+	  Many laptops released in 2008/9/10 have two GPUs with a multiplexer
+	  to switch between them. This adds support for dynamic switching when
+          X isn't running and delayed switching until the next logoff. This
+	  feature is called hybrid graphics, ATI PowerXpress, and Nvidia
+	  HybridPower.
diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
new file mode 100644
index 000000000..14ca30b75
--- /dev/null
+++ b/drivers/gpu/vga/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_VGA_ARB)  += vgaarb.o
+obj-$(CONFIG_VGA_SWITCHEROO) += vga_switcheroo.o
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
new file mode 100644
index 000000000..a132c37d7
--- /dev/null
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -0,0 +1,1108 @@
+/*
+ * vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs
+ *
+ * Copyright (c) 2010 Red Hat Inc.
+ * Author : Dave Airlie <airlied@redhat.com>
+ *
+ * Copyright (c) 2015 Lukas Wunner <lukas@wunner.de>
+ *
+ * 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 (including the next
+ * paragraph) 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 AUTHORS OR COPYRIGHT HOLDERS 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.
+ *
+ */
+
+#define pr_fmt(fmt) "vga_switcheroo: " fmt
+
+#include <linux/apple-gmux.h>
+#include <linux/console.h>
+#include <linux/debugfs.h>
+#include <linux/fb.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/vgaarb.h>
+#include <linux/vga_switcheroo.h>
+
+/**
+ * DOC: Overview
+ *
+ * vga_switcheroo is the Linux subsystem for laptop hybrid graphics.
+ * These come in two flavors:
+ *
+ * * muxed: Dual GPUs with a multiplexer chip to switch outputs between GPUs.
+ * * muxless: Dual GPUs but only one of them is connected to outputs.
+ *   The other one is merely used to offload rendering, its results
+ *   are copied over PCIe into the framebuffer. On Linux this is
+ *   supported with DRI PRIME.
+ *
+ * Hybrid graphics started to appear in the late Naughties and were initially
+ * all muxed. Newer laptops moved to a muxless architecture for cost reasons.
+ * A notable exception is the MacBook Pro which continues to use a mux.
+ * Muxes come with varying capabilities: Some switch only the panel, others
+ * can also switch external displays. Some switch all display pins at once
+ * while others can switch just the DDC lines. (To allow EDID probing
+ * for the inactive GPU.) Also, muxes are often used to cut power to the
+ * discrete GPU while it is not used.
+ *
+ * DRM drivers register GPUs with vga_switcheroo, these are henceforth called
+ * clients. The mux is called the handler. Muxless machines also register a
+ * handler to control the power state of the discrete GPU, its ->switchto
+ * callback is a no-op for obvious reasons. The discrete GPU is often equipped
+ * with an HDA controller for the HDMI/DP audio signal, this will also
+ * register as a client so that vga_switcheroo can take care of the correct
+ * suspend/resume order when changing the discrete GPU's power state. In total
+ * there can thus be up to three clients: Two vga clients (GPUs) and one audio
+ * client (on the discrete GPU). The code is mostly prepared to support
+ * machines with more than two GPUs should they become available.
+ *
+ * The GPU to which the outputs are currently switched is called the
+ * active client in vga_switcheroo parlance. The GPU not in use is the
+ * inactive client. When the inactive client's DRM driver is loaded,
+ * it will be unable to probe the panel's EDID and hence depends on
+ * VBIOS to provide its display modes. If the VBIOS modes are bogus or
+ * if there is no VBIOS at all (which is common on the MacBook Pro),
+ * a client may alternatively request that the DDC lines are temporarily
+ * switched to it, provided that the handler supports this. Switching
+ * only the DDC lines and not the entire output avoids unnecessary
+ * flickering.
+ */
+
+/**
+ * struct vga_switcheroo_client - registered client
+ * @pdev: client pci device
+ * @fb_info: framebuffer to which console is remapped on switching
+ * @pwr_state: current power state if manual power control is used.
+ *	For driver power control, call vga_switcheroo_pwr_state().
+ * @ops: client callbacks
+ * @id: client identifier. Determining the id requires the handler,
+ *	so gpus are initially assigned VGA_SWITCHEROO_UNKNOWN_ID
+ *	and later given their true id in vga_switcheroo_enable()
+ * @active: whether the outputs are currently switched to this client
+ * @driver_power_control: whether power state is controlled by the driver's
+ *	runtime pm. If true, writing ON and OFF to the vga_switcheroo debugfs
+ *	interface is a no-op so as not to interfere with runtime pm
+ * @list: client list
+ * @vga_dev: pci device, indicate which GPU is bound to current audio client
+ *
+ * Registered client. A client can be either a GPU or an audio device on a GPU.
+ * For audio clients, the @fb_info and @active members are bogus. For GPU
+ * clients, the @vga_dev is bogus.
+ */
+struct vga_switcheroo_client {
+	struct pci_dev *pdev;
+	struct fb_info *fb_info;
+	enum vga_switcheroo_state pwr_state;
+	const struct vga_switcheroo_client_ops *ops;
+	enum vga_switcheroo_client_id id;
+	bool active;
+	bool driver_power_control;
+	struct list_head list;
+	struct pci_dev *vga_dev;
+};
+
+/*
+ * protects access to struct vgasr_priv
+ */
+static DEFINE_MUTEX(vgasr_mutex);
+
+/**
+ * struct vgasr_priv - vga_switcheroo private data
+ * @active: whether vga_switcheroo is enabled.
+ *	Prerequisite is the registration of two GPUs and a handler
+ * @delayed_switch_active: whether a delayed switch is pending
+ * @delayed_client_id: client to which a delayed switch is pending
+ * @debugfs_root: directory for vga_switcheroo debugfs interface
+ * @switch_file: file for vga_switcheroo debugfs interface
+ * @registered_clients: number of registered GPUs
+ *	(counting only vga clients, not audio clients)
+ * @clients: list of registered clients
+ * @handler: registered handler
+ * @handler_flags: flags of registered handler
+ * @mux_hw_lock: protects mux state
+ *	(in particular while DDC lines are temporarily switched)
+ * @old_ddc_owner: client to which DDC lines will be switched back on unlock
+ *
+ * vga_switcheroo private data. Currently only one vga_switcheroo instance
+ * per system is supported.
+ */
+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;
+
+	const struct vga_switcheroo_handler *handler;
+	enum vga_switcheroo_handler_flags_t handler_flags;
+	struct mutex mux_hw_lock;
+	int old_ddc_owner;
+};
+
+#define ID_BIT_AUDIO		0x100
+#define client_is_audio(c)		((c)->id & ID_BIT_AUDIO)
+#define client_is_vga(c)		(!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),
+	.mux_hw_lock = __MUTEX_INITIALIZER(vgasr_priv.mux_hw_lock),
+};
+
+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_is_vga(client) ||
+		     client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
+			continue;
+
+		ret = vgasr_priv.handler->get_client_id(client->pdev);
+		if (ret < 0)
+			return;
+
+		client->id = ret;
+	}
+
+	list_for_each_entry(client, &vgasr_priv.clients, list) {
+		if (!client_is_audio(client) ||
+		     client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
+			continue;
+
+		ret = vgasr_priv.handler->get_client_id(client->vga_dev);
+		if (ret < 0)
+			return;
+
+		client->id = ret | ID_BIT_AUDIO;
+		if (client->ops->gpu_bound)
+			client->ops->gpu_bound(client->pdev, ret);
+	}
+
+	vga_switcheroo_debugfs_init(&vgasr_priv);
+	vgasr_priv.active = true;
+}
+
+/**
+ * vga_switcheroo_register_handler() - register handler
+ * @handler: handler callbacks
+ * @handler_flags: handler flags
+ *
+ * Register handler. Enable vga_switcheroo if two vga clients have already
+ * registered.
+ *
+ * Return: 0 on success, -EINVAL if a handler was already registered.
+ */
+int vga_switcheroo_register_handler(
+			  const struct vga_switcheroo_handler *handler,
+			  enum vga_switcheroo_handler_flags_t handler_flags)
+{
+	mutex_lock(&vgasr_mutex);
+	if (vgasr_priv.handler) {
+		mutex_unlock(&vgasr_mutex);
+		return -EINVAL;
+	}
+
+	vgasr_priv.handler = handler;
+	vgasr_priv.handler_flags = handler_flags;
+	if (vga_switcheroo_ready()) {
+		pr_info("enabled\n");
+		vga_switcheroo_enable();
+	}
+	mutex_unlock(&vgasr_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(vga_switcheroo_register_handler);
+
+/**
+ * vga_switcheroo_unregister_handler() - unregister handler
+ *
+ * Unregister handler. Disable vga_switcheroo.
+ */
+void vga_switcheroo_unregister_handler(void)
+{
+	mutex_lock(&vgasr_mutex);
+	mutex_lock(&vgasr_priv.mux_hw_lock);
+	vgasr_priv.handler_flags = 0;
+	vgasr_priv.handler = NULL;
+	if (vgasr_priv.active) {
+		pr_info("disabled\n");
+		vga_switcheroo_debugfs_fini(&vgasr_priv);
+		vgasr_priv.active = false;
+	}
+	mutex_unlock(&vgasr_priv.mux_hw_lock);
+	mutex_unlock(&vgasr_mutex);
+}
+EXPORT_SYMBOL(vga_switcheroo_unregister_handler);
+
+/**
+ * vga_switcheroo_handler_flags() - obtain handler flags
+ *
+ * Helper for clients to obtain the handler flags bitmask.
+ *
+ * Return: Handler flags. A value of 0 means that no handler is registered
+ * or that the handler has no special capabilities.
+ */
+enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void)
+{
+	return vgasr_priv.handler_flags;
+}
+EXPORT_SYMBOL(vga_switcheroo_handler_flags);
+
+static int register_client(struct pci_dev *pdev,
+			   const struct vga_switcheroo_client_ops *ops,
+			   enum vga_switcheroo_client_id id,
+			   struct pci_dev *vga_dev,
+			   bool active,
+			   bool driver_power_control)
+{
+	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;
+	client->driver_power_control = driver_power_control;
+	client->vga_dev = vga_dev;
+
+	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()) {
+		pr_info("enabled\n");
+		vga_switcheroo_enable();
+	}
+	mutex_unlock(&vgasr_mutex);
+	return 0;
+}
+
+/**
+ * vga_switcheroo_register_client - register vga client
+ * @pdev: client pci device
+ * @ops: client callbacks
+ * @driver_power_control: whether power state is controlled by the driver's
+ *	runtime pm
+ *
+ * Register vga client (GPU). Enable vga_switcheroo if another GPU and a
+ * handler have already registered. The power state of the client is assumed
+ * to be ON. Beforehand, vga_switcheroo_client_probe_defer() shall be called
+ * to ensure that all prerequisites are met.
+ *
+ * Return: 0 on success, -ENOMEM on memory allocation error.
+ */
+int vga_switcheroo_register_client(struct pci_dev *pdev,
+				   const struct vga_switcheroo_client_ops *ops,
+				   bool driver_power_control)
+{
+	return register_client(pdev, ops, VGA_SWITCHEROO_UNKNOWN_ID, NULL,
+			       pdev == vga_default_device(),
+			       driver_power_control);
+}
+EXPORT_SYMBOL(vga_switcheroo_register_client);
+
+/**
+ * vga_switcheroo_register_audio_client - register audio client
+ * @pdev: client pci device
+ * @ops: client callbacks
+ * @vga_dev:  pci device which is bound to current audio client
+ *
+ * Register audio client (audio device on a GPU). The client is assumed
+ * to use runtime PM. Beforehand, vga_switcheroo_client_probe_defer()
+ * shall be called to ensure that all prerequisites are met.
+ *
+ * Return: 0 on success, -ENOMEM on memory allocation error, -EINVAL on getting
+ * client id error.
+ */
+int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
+			const struct vga_switcheroo_client_ops *ops,
+			struct pci_dev *vga_dev)
+{
+	enum vga_switcheroo_client_id id = VGA_SWITCHEROO_UNKNOWN_ID;
+
+	/*
+	 * if vga_switcheroo has enabled, that mean two GPU clients and also
+	 * handler are registered. Get audio client id from bound GPU client
+	 * id directly, otherwise, set it as VGA_SWITCHEROO_UNKNOWN_ID,
+	 * it will set to correct id in later when vga_switcheroo_enable()
+	 * is called.
+	 */
+	mutex_lock(&vgasr_mutex);
+	if (vgasr_priv.active) {
+		id = vgasr_priv.handler->get_client_id(vga_dev);
+		if (id < 0) {
+			mutex_unlock(&vgasr_mutex);
+			return -EINVAL;
+		}
+		/* notify if GPU has been already bound */
+		if (ops->gpu_bound)
+			ops->gpu_bound(pdev, id);
+	}
+	mutex_unlock(&vgasr_mutex);
+
+	return register_client(pdev, ops, id | ID_BIT_AUDIO, vga_dev,
+			       false, true);
+}
+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,
+		    enum vga_switcheroo_client_id 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)
+			return client;
+	return NULL;
+}
+
+/**
+ * vga_switcheroo_client_probe_defer() - whether to defer probing a given client
+ * @pdev: client pci device
+ *
+ * Determine whether any prerequisites are not fulfilled to probe a given
+ * client. Drivers shall invoke this early on in their ->probe callback
+ * and return %-EPROBE_DEFER if it evaluates to %true. Thou shalt not
+ * register the client ere thou hast called this.
+ *
+ * Return: %true if probing should be deferred, otherwise %false.
+ */
+bool vga_switcheroo_client_probe_defer(struct pci_dev *pdev)
+{
+	if ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY) {
+		/*
+		 * apple-gmux is needed on pre-retina MacBook Pro
+		 * to probe the panel if pdev is the inactive GPU.
+		 */
+		if (apple_gmux_present() && pdev != vga_default_device() &&
+		    !vgasr_priv.handler_flags)
+			return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(vga_switcheroo_client_probe_defer);
+
+static enum vga_switcheroo_state
+vga_switcheroo_pwr_state(struct vga_switcheroo_client *client)
+{
+	if (client->driver_power_control)
+		if (pm_runtime_enabled(&client->pdev->dev) &&
+		    pm_runtime_active(&client->pdev->dev))
+			return VGA_SWITCHEROO_ON;
+		else
+			return VGA_SWITCHEROO_OFF;
+	else
+		return client->pwr_state;
+}
+
+/**
+ * vga_switcheroo_get_client_state() - obtain power state of a given client
+ * @pdev: client pci device
+ *
+ * Obtain power state of a given client as seen from vga_switcheroo.
+ * The function is only called from hda_intel.c.
+ *
+ * Return: Power state.
+ */
+enum vga_switcheroo_state vga_switcheroo_get_client_state(struct pci_dev *pdev)
+{
+	struct vga_switcheroo_client *client;
+	enum vga_switcheroo_state ret;
+
+	mutex_lock(&vgasr_mutex);
+	client = find_client_from_pci(&vgasr_priv.clients, pdev);
+	if (!client)
+		ret = VGA_SWITCHEROO_NOT_FOUND;
+	else
+		ret = vga_switcheroo_pwr_state(client);
+	mutex_unlock(&vgasr_mutex);
+	return ret;
+}
+EXPORT_SYMBOL(vga_switcheroo_get_client_state);
+
+/**
+ * vga_switcheroo_unregister_client() - unregister client
+ * @pdev: client pci device
+ *
+ * Unregister client. Disable vga_switcheroo if this is a vga client (GPU).
+ */
+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) {
+		pr_info("disabled\n");
+		vga_switcheroo_debugfs_fini(&vgasr_priv);
+		vgasr_priv.active = false;
+	}
+	mutex_unlock(&vgasr_mutex);
+}
+EXPORT_SYMBOL(vga_switcheroo_unregister_client);
+
+/**
+ * vga_switcheroo_client_fb_set() - set framebuffer of a given client
+ * @pdev: client pci device
+ * @info: framebuffer
+ *
+ * Set framebuffer of a given client. The console will be remapped to this
+ * on switching.
+ */
+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);
+
+/**
+ * vga_switcheroo_lock_ddc() - temporarily switch DDC lines to a given client
+ * @pdev: client pci device
+ *
+ * Temporarily switch DDC lines to the client identified by @pdev
+ * (but leave the outputs otherwise switched to where they are).
+ * This allows the inactive client to probe EDID. The DDC lines must
+ * afterwards be switched back by calling vga_switcheroo_unlock_ddc(),
+ * even if this function returns an error.
+ *
+ * Return: Previous DDC owner on success or a negative int on error.
+ * Specifically, %-ENODEV if no handler has registered or if the handler
+ * does not support switching the DDC lines. Also, a negative value
+ * returned by the handler is propagated back to the caller.
+ * The return value has merely an informational purpose for any caller
+ * which might be interested in it. It is acceptable to ignore the return
+ * value and simply rely on the result of the subsequent EDID probe,
+ * which will be %NULL if DDC switching failed.
+ */
+int vga_switcheroo_lock_ddc(struct pci_dev *pdev)
+{
+	enum vga_switcheroo_client_id id;
+
+	mutex_lock(&vgasr_priv.mux_hw_lock);
+	if (!vgasr_priv.handler || !vgasr_priv.handler->switch_ddc) {
+		vgasr_priv.old_ddc_owner = -ENODEV;
+		return -ENODEV;
+	}
+
+	id = vgasr_priv.handler->get_client_id(pdev);
+	vgasr_priv.old_ddc_owner = vgasr_priv.handler->switch_ddc(id);
+	return vgasr_priv.old_ddc_owner;
+}
+EXPORT_SYMBOL(vga_switcheroo_lock_ddc);
+
+/**
+ * vga_switcheroo_unlock_ddc() - switch DDC lines back to previous owner
+ * @pdev: client pci device
+ *
+ * Switch DDC lines back to the previous owner after calling
+ * vga_switcheroo_lock_ddc(). This must be called even if
+ * vga_switcheroo_lock_ddc() returned an error.
+ *
+ * Return: Previous DDC owner on success (i.e. the client identifier of @pdev)
+ * or a negative int on error.
+ * Specifically, %-ENODEV if no handler has registered or if the handler
+ * does not support switching the DDC lines. Also, a negative value
+ * returned by the handler is propagated back to the caller.
+ * Finally, invoking this function without calling vga_switcheroo_lock_ddc()
+ * first is not allowed and will result in %-EINVAL.
+ */
+int vga_switcheroo_unlock_ddc(struct pci_dev *pdev)
+{
+	enum vga_switcheroo_client_id id;
+	int ret = vgasr_priv.old_ddc_owner;
+
+	if (WARN_ON_ONCE(!mutex_is_locked(&vgasr_priv.mux_hw_lock)))
+		return -EINVAL;
+
+	if (vgasr_priv.old_ddc_owner >= 0) {
+		id = vgasr_priv.handler->get_client_id(pdev);
+		if (vgasr_priv.old_ddc_owner != id)
+			ret = vgasr_priv.handler->switch_ddc(
+						     vgasr_priv.old_ddc_owner);
+	}
+	mutex_unlock(&vgasr_priv.mux_hw_lock);
+	return ret;
+}
+EXPORT_SYMBOL(vga_switcheroo_unlock_ddc);
+
+/**
+ * DOC: Manual switching and manual power control
+ *
+ * In this mode of use, the file /sys/kernel/debug/vgaswitcheroo/switch
+ * can be read to retrieve the current vga_switcheroo state and commands
+ * can be written to it to change the state. The file appears as soon as
+ * two GPU drivers and one handler have registered with vga_switcheroo.
+ * The following commands are understood:
+ *
+ * * OFF: Power off the device not in use.
+ * * ON: Power on the device not in use.
+ * * IGD: Switch to the integrated graphics device.
+ *   Power on the integrated GPU if necessary, power off the discrete GPU.
+ *   Prerequisite is that no user space processes (e.g. Xorg, alsactl)
+ *   have opened device files of the GPUs or the audio client. If the
+ *   switch fails, the user may invoke lsof(8) or fuser(1) on /dev/dri/
+ *   and /dev/snd/controlC1 to identify processes blocking the switch.
+ * * DIS: Switch to the discrete graphics device.
+ * * DIGD: Delayed switch to the integrated graphics device.
+ *   This will perform the switch once the last user space process has
+ *   closed the device files of the GPUs and the audio client.
+ * * DDIS: Delayed switch to the discrete graphics device.
+ * * MIGD: Mux-only switch to the integrated graphics device.
+ *   Does not remap console or change the power state of either gpu.
+ *   If the integrated GPU is currently off, the screen will turn black.
+ *   If it is on, the screen will show whatever happens to be in VRAM.
+ *   Either way, the user has to blindly enter the command to switch back.
+ * * MDIS: Mux-only switch to the discrete graphics device.
+ *
+ * For GPUs whose power state is controlled by the driver's runtime pm,
+ * the ON and OFF commands are a no-op (see next section).
+ *
+ * For muxless machines, the IGD/DIS, DIGD/DDIS and MIGD/MDIS commands
+ * should not be used.
+ */
+
+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:%s\n", i,
+			   client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" :
+								     "IGD",
+			   client_is_vga(client) ? "" : "-Audio",
+			   client->active ? '+' : ' ',
+			   client->driver_power_control ? "Dyn" : "",
+			   vga_switcheroo_pwr_state(client) ? "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 (client->driver_power_control)
+		return 0;
+	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)
+{
+	if (client->driver_power_control)
+		return 0;
+	/* 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(enum vga_switcheroo_client_id id,
+			    enum vga_switcheroo_state state)
+{
+	struct vga_switcheroo_client *client;
+
+	client = find_client_from_id(&vgasr_priv.clients, id | ID_BIT_AUDIO);
+	if (client)
+		client->ops->set_gpu_state(client->pdev, 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 (vga_switcheroo_pwr_state(new_client) == 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;
+
+	/* let HDA controller autosuspend if GPU uses driver power control */
+	if (!active->driver_power_control)
+		set_audio_state(active->id, VGA_SWITCHEROO_OFF);
+
+	if (new_client->fb_info) {
+		struct fb_event event;
+
+		console_lock();
+		event.info = new_client->fb_info;
+		fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
+		console_unlock();
+	}
+
+	mutex_lock(&vgasr_priv.mux_hw_lock);
+	ret = vgasr_priv.handler->switchto(new_client->id);
+	mutex_unlock(&vgasr_priv.mux_hw_lock);
+	if (ret)
+		return ret;
+
+	if (new_client->ops->reprobe)
+		new_client->ops->reprobe(new_client->pdev);
+
+	if (vga_switcheroo_pwr_state(active) == VGA_SWITCHEROO_ON)
+		vga_switchoff(active);
+
+	/* let HDA controller autoresume if GPU uses driver power control */
+	if (!new_client->driver_power_control)
+		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)) {
+			pr_err("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];
+	int ret;
+	bool delay = false, can_switch;
+	bool just_mux = false;
+	enum vga_switcheroo_client_id client_id = VGA_SWITCHEROO_UNKNOWN_ID;
+	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;
+			if (client->driver_power_control)
+				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->driver_power_control)
+				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 == VGA_SWITCHEROO_UNKNOWN_ID)
+		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) {
+		mutex_lock(&vgasr_priv.mux_hw_lock);
+		ret = vgasr_priv.handler->switchto(client_id);
+		mutex_unlock(&vgasr_priv.mux_hw_lock);
+		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) {
+		ret = vga_switchto_stage1(client);
+		if (ret)
+			pr_err("switching failed stage 1 %d\n", ret);
+
+		ret = vga_switchto_stage2(client);
+		if (ret)
+			pr_err("switching failed stage 2 %d\n", ret);
+
+	} else {
+		pr_info("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)
+			pr_err("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)
+{
+	debugfs_remove(priv->switch_file);
+	priv->switch_file = NULL;
+
+	debugfs_remove(priv->debugfs_root);
+	priv->debugfs_root = NULL;
+}
+
+static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv)
+{
+	static const char mp[] = "/sys/kernel/debug";
+
+	/* already initialised */
+	if (priv->debugfs_root)
+		return 0;
+	priv->debugfs_root = debugfs_create_dir("vgaswitcheroo", NULL);
+
+	if (!priv->debugfs_root) {
+		pr_err("Cannot create %s/vgaswitcheroo\n", mp);
+		goto fail;
+	}
+
+	priv->switch_file = debugfs_create_file("switch", 0644,
+						priv->debugfs_root, NULL,
+						&vga_switcheroo_debugfs_fops);
+	if (!priv->switch_file) {
+		pr_err("cannot create %s/vgaswitcheroo/switch\n", mp);
+		goto fail;
+	}
+	return 0;
+fail:
+	vga_switcheroo_debugfs_fini(priv);
+	return -1;
+}
+
+/**
+ * vga_switcheroo_process_delayed_switch() - helper for delayed switching
+ *
+ * Process a delayed switch if one is pending. DRM drivers should call this
+ * from their ->lastclose callback.
+ *
+ * Return: 0 on success. -EINVAL if no delayed switch is pending, if the client
+ * has unregistered in the meantime or if there are other clients blocking the
+ * switch. If the actual switch fails, an error is reported and 0 is returned.
+ */
+int vga_switcheroo_process_delayed_switch(void)
+{
+	struct vga_switcheroo_client *client;
+	int ret;
+	int err = -EINVAL;
+
+	mutex_lock(&vgasr_mutex);
+	if (!vgasr_priv.delayed_switch_active)
+		goto err;
+
+	pr_info("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;
+
+	ret = vga_switchto_stage2(client);
+	if (ret)
+		pr_err("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);
+
+/**
+ * DOC: Driver power control
+ *
+ * In this mode of use, the discrete GPU automatically powers up and down at
+ * the discretion of the driver's runtime pm. On muxed machines, the user may
+ * still influence the muxer state by way of the debugfs interface, however
+ * the ON and OFF commands become a no-op for the discrete GPU.
+ *
+ * This mode is the default on Nvidia HybridPower/Optimus and ATI PowerXpress.
+ * Specifying nouveau.runpm=0, radeon.runpm=0 or amdgpu.runpm=0 on the kernel
+ * command line disables it.
+ *
+ * After the GPU has been suspended, the handler needs to be called to cut
+ * power to the GPU. Likewise it needs to reinstate power before the GPU
+ * can resume. This is achieved by vga_switcheroo_init_domain_pm_ops(),
+ * which augments the GPU's suspend/resume functions by the requisite
+ * calls to the handler.
+ *
+ * When the audio device resumes, the GPU needs to be woken. This is achieved
+ * by a PCI quirk which calls device_link_add() to declare a dependency on the
+ * GPU. That way, the GPU is kept awake whenever and as long as the audio
+ * device is in use.
+ *
+ * On muxed machines, if the mux is initially switched to the discrete GPU,
+ * the user ends up with a black screen when the GPU powers down after boot.
+ * As a workaround, the mux is forced to the integrated GPU on runtime suspend,
+ * cf. https://bugs.freedesktop.org/show_bug.cgi?id=75917
+ */
+
+static void vga_switcheroo_power_switch(struct pci_dev *pdev,
+					enum vga_switcheroo_state state)
+{
+	struct vga_switcheroo_client *client;
+
+	if (!vgasr_priv.handler->power_state)
+		return;
+
+	client = find_client_from_pci(&vgasr_priv.clients, pdev);
+	if (!client)
+		return;
+
+	if (!client->driver_power_control)
+		return;
+
+	vgasr_priv.handler->power_state(client->id, state);
+}
+
+/* switcheroo power domain */
+static int vga_switcheroo_runtime_suspend(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	int ret;
+
+	ret = dev->bus->pm->runtime_suspend(dev);
+	if (ret)
+		return ret;
+	mutex_lock(&vgasr_mutex);
+	if (vgasr_priv.handler->switchto) {
+		mutex_lock(&vgasr_priv.mux_hw_lock);
+		vgasr_priv.handler->switchto(VGA_SWITCHEROO_IGD);
+		mutex_unlock(&vgasr_priv.mux_hw_lock);
+	}
+	pci_bus_set_current_state(pdev->bus, PCI_D3cold);
+	vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_OFF);
+	mutex_unlock(&vgasr_mutex);
+	return 0;
+}
+
+static int vga_switcheroo_runtime_resume(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	int ret;
+
+	mutex_lock(&vgasr_mutex);
+	vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_ON);
+	mutex_unlock(&vgasr_mutex);
+	pci_wakeup_bus(pdev->bus);
+	ret = dev->bus->pm->runtime_resume(dev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+/**
+ * vga_switcheroo_init_domain_pm_ops() - helper for driver power control
+ * @dev: vga client device
+ * @domain: power domain
+ *
+ * Helper for GPUs whose power state is controlled by the driver's runtime pm.
+ * After the GPU has been suspended, the handler needs to be called to cut
+ * power to the GPU. Likewise it needs to reinstate power before the GPU
+ * can resume. To this end, this helper augments the suspend/resume functions
+ * by the requisite calls to the handler. It needs only be called on platforms
+ * where the power switch is separate to the device being powered down.
+ */
+int vga_switcheroo_init_domain_pm_ops(struct device *dev,
+				      struct dev_pm_domain *domain)
+{
+	/* copy over all the bus versions */
+	if (dev->bus && dev->bus->pm) {
+		domain->ops = *dev->bus->pm;
+		domain->ops.runtime_suspend = vga_switcheroo_runtime_suspend;
+		domain->ops.runtime_resume = vga_switcheroo_runtime_resume;
+
+		dev_pm_domain_set(dev, domain);
+		return 0;
+	}
+	dev_pm_domain_set(dev, NULL);
+	return -EINVAL;
+}
+EXPORT_SYMBOL(vga_switcheroo_init_domain_pm_ops);
+
+void vga_switcheroo_fini_domain_pm_ops(struct device *dev)
+{
+	dev_pm_domain_set(dev, NULL);
+}
+EXPORT_SYMBOL(vga_switcheroo_fini_domain_pm_ops);
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
new file mode 100644
index 000000000..c61b04555
--- /dev/null
+++ b/drivers/gpu/vga/vgaarb.c
@@ -0,0 +1,1512 @@
+/*
+ * vgaarb.c: Implements the VGA arbitration. For details refer to
+ * Documentation/gpu/vgaarbiter.rst
+ *
+ *
+ * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
+ * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
+ * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
+ *
+ * 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 (including the next
+ * paragraph) 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 AUTHORS OR COPYRIGHT HOLDERS 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.
+ *
+ */
+
+#define pr_fmt(fmt) "vgaarb: " fmt
+
+#define vgaarb_dbg(dev, fmt, arg...)	dev_dbg(dev, "vgaarb: " fmt, ##arg)
+#define vgaarb_info(dev, fmt, arg...)	dev_info(dev, "vgaarb: " fmt, ##arg)
+#define vgaarb_err(dev, fmt, arg...)	dev_err(dev, "vgaarb: " fmt, ##arg)
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/sched/signal.h>
+#include <linux/wait.h>
+#include <linux/spinlock.h>
+#include <linux/poll.h>
+#include <linux/miscdevice.h>
+#include <linux/slab.h>
+#include <linux/screen_info.h>
+
+#include <linux/uaccess.h>
+
+#include <linux/vgaarb.h>
+
+static void vga_arbiter_notify_clients(void);
+/*
+ * We keep a list of all vga devices in the system to speed
+ * up the various operations of the arbiter
+ */
+struct vga_device {
+	struct list_head list;
+	struct pci_dev *pdev;
+	unsigned int decodes;	/* what does it decodes */
+	unsigned int owns;	/* what does it owns */
+	unsigned int locks;	/* what does it locks */
+	unsigned int io_lock_cnt;	/* legacy IO lock count */
+	unsigned int mem_lock_cnt;	/* legacy MEM lock count */
+	unsigned int io_norm_cnt;	/* normal IO count */
+	unsigned int mem_norm_cnt;	/* normal MEM count */
+	bool bridge_has_one_vga;
+	/* allow IRQ enable/disable hook */
+	void *cookie;
+	void (*irq_set_state)(void *cookie, bool enable);
+	unsigned int (*set_vga_decode)(void *cookie, bool decode);
+};
+
+static LIST_HEAD(vga_list);
+static int vga_count, vga_decode_count;
+static bool vga_arbiter_used;
+static DEFINE_SPINLOCK(vga_lock);
+static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
+
+
+static const char *vga_iostate_to_str(unsigned int iostate)
+{
+	/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
+	iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
+	switch (iostate) {
+	case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
+		return "io+mem";
+	case VGA_RSRC_LEGACY_IO:
+		return "io";
+	case VGA_RSRC_LEGACY_MEM:
+		return "mem";
+	}
+	return "none";
+}
+
+static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
+{
+	/* we could in theory hand out locks on IO and mem
+	 * separately to userspace but it can cause deadlocks */
+	if (strncmp(buf, "none", 4) == 0) {
+		*io_state = VGA_RSRC_NONE;
+		return 1;
+	}
+
+	/* XXX We're not chekcing the str_size! */
+	if (strncmp(buf, "io+mem", 6) == 0)
+		goto both;
+	else if (strncmp(buf, "io", 2) == 0)
+		goto both;
+	else if (strncmp(buf, "mem", 3) == 0)
+		goto both;
+	return 0;
+both:
+	*io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
+	return 1;
+}
+
+/* this is only used a cookie - it should not be dereferenced */
+static struct pci_dev *vga_default;
+
+static void vga_arb_device_card_gone(struct pci_dev *pdev);
+
+/* Find somebody in our list */
+static struct vga_device *vgadev_find(struct pci_dev *pdev)
+{
+	struct vga_device *vgadev;
+
+	list_for_each_entry(vgadev, &vga_list, list)
+		if (pdev == vgadev->pdev)
+			return vgadev;
+	return NULL;
+}
+
+/**
+ * vga_default_device - return the default VGA device, for vgacon
+ *
+ * This can be defined by the platform. The default implementation
+ * is rather dumb and will probably only work properly on single
+ * vga card setups and/or x86 platforms.
+ *
+ * If your VGA default device is not PCI, you'll have to return
+ * NULL here. In this case, I assume it will not conflict with
+ * any PCI card. If this is not true, I'll have to define two archs
+ * hooks for enabling/disabling the VGA default device if that is
+ * possible. This may be a problem with real _ISA_ VGA cards, in
+ * addition to a PCI one. I don't know at this point how to deal
+ * with that card. Can theirs IOs be disabled at all ? If not, then
+ * I suppose it's a matter of having the proper arch hook telling
+ * us about it, so we basically never allow anybody to succeed a
+ * vga_get()...
+ */
+struct pci_dev *vga_default_device(void)
+{
+	return vga_default;
+}
+EXPORT_SYMBOL_GPL(vga_default_device);
+
+void vga_set_default_device(struct pci_dev *pdev)
+{
+	if (vga_default == pdev)
+		return;
+
+	pci_dev_put(vga_default);
+	vga_default = pci_dev_get(pdev);
+}
+
+static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
+{
+	if (vgadev->irq_set_state)
+		vgadev->irq_set_state(vgadev->cookie, state);
+}
+
+
+/* If we don't ever use VGA arb we should avoid
+   turning off anything anywhere due to old X servers getting
+   confused about the boot device not being VGA */
+static void vga_check_first_use(void)
+{
+	/* we should inform all GPUs in the system that
+	 * VGA arb has occurred and to try and disable resources
+	 * if they can */
+	if (!vga_arbiter_used) {
+		vga_arbiter_used = true;
+		vga_arbiter_notify_clients();
+	}
+}
+
+static struct vga_device *__vga_tryget(struct vga_device *vgadev,
+				       unsigned int rsrc)
+{
+	struct device *dev = &vgadev->pdev->dev;
+	unsigned int wants, legacy_wants, match;
+	struct vga_device *conflict;
+	unsigned int pci_bits;
+	u32 flags = 0;
+
+	/* Account for "normal" resources to lock. If we decode the legacy,
+	 * counterpart, we need to request it as well
+	 */
+	if ((rsrc & VGA_RSRC_NORMAL_IO) &&
+	    (vgadev->decodes & VGA_RSRC_LEGACY_IO))
+		rsrc |= VGA_RSRC_LEGACY_IO;
+	if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
+	    (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
+		rsrc |= VGA_RSRC_LEGACY_MEM;
+
+	vgaarb_dbg(dev, "%s: %d\n", __func__, rsrc);
+	vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns);
+
+	/* Check what resources we need to acquire */
+	wants = rsrc & ~vgadev->owns;
+
+	/* We already own everything, just mark locked & bye bye */
+	if (wants == 0)
+		goto lock_them;
+
+	/* We don't need to request a legacy resource, we just enable
+	 * appropriate decoding and go
+	 */
+	legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
+	if (legacy_wants == 0)
+		goto enable_them;
+
+	/* Ok, we don't, let's find out how we need to kick off */
+	list_for_each_entry(conflict, &vga_list, list) {
+		unsigned int lwants = legacy_wants;
+		unsigned int change_bridge = 0;
+
+		/* Don't conflict with myself */
+		if (vgadev == conflict)
+			continue;
+
+		/* Check if the architecture allows a conflict between those
+		 * 2 devices or if they are on separate domains
+		 */
+		if (!vga_conflicts(vgadev->pdev, conflict->pdev))
+			continue;
+
+		/* We have a possible conflict. before we go further, we must
+		 * check if we sit on the same bus as the conflicting device.
+		 * if we don't, then we must tie both IO and MEM resources
+		 * together since there is only a single bit controlling
+		 * VGA forwarding on P2P bridges
+		 */
+		if (vgadev->pdev->bus != conflict->pdev->bus) {
+			change_bridge = 1;
+			lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
+		}
+
+		/* Check if the guy has a lock on the resource. If he does,
+		 * return the conflicting entry
+		 */
+		if (conflict->locks & lwants)
+			return conflict;
+
+		/* Ok, now check if it owns the resource we want.  We can
+		 * lock resources that are not decoded, therefore a device
+		 * can own resources it doesn't decode.
+		 */
+		match = lwants & conflict->owns;
+		if (!match)
+			continue;
+
+		/* looks like he doesn't have a lock, we can steal
+		 * them from him
+		 */
+
+		flags = 0;
+		pci_bits = 0;
+
+		/* If we can't control legacy resources via the bridge, we
+		 * also need to disable normal decoding.
+		 */
+		if (!conflict->bridge_has_one_vga) {
+			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)
+				pci_bits |= PCI_COMMAND_MEMORY;
+			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)
+				pci_bits |= PCI_COMMAND_IO;
+
+			if (pci_bits) {
+				vga_irq_set_state(conflict, false);
+				flags |= PCI_VGA_STATE_CHANGE_DECODES;
+			}
+		}
+
+		if (change_bridge)
+			flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
+
+		pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
+		conflict->owns &= ~match;
+
+		/* If we disabled normal decoding, reflect it in owns */
+		if (pci_bits & PCI_COMMAND_MEMORY)
+			conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
+		if (pci_bits & PCI_COMMAND_IO)
+			conflict->owns &= ~VGA_RSRC_NORMAL_IO;
+	}
+
+enable_them:
+	/* ok dude, we got it, everybody conflicting has been disabled, let's
+	 * enable us.  Mark any bits in "owns" regardless of whether we
+	 * decoded them.  We can lock resources we don't decode, therefore
+	 * we must track them via "owns".
+	 */
+	flags = 0;
+	pci_bits = 0;
+
+	if (!vgadev->bridge_has_one_vga) {
+		flags |= PCI_VGA_STATE_CHANGE_DECODES;
+		if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
+			pci_bits |= PCI_COMMAND_MEMORY;
+		if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
+			pci_bits |= PCI_COMMAND_IO;
+	}
+	if (wants & VGA_RSRC_LEGACY_MASK)
+		flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
+
+	pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);
+
+	if (!vgadev->bridge_has_one_vga)
+		vga_irq_set_state(vgadev, true);
+
+	vgadev->owns |= wants;
+lock_them:
+	vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
+	if (rsrc & VGA_RSRC_LEGACY_IO)
+		vgadev->io_lock_cnt++;
+	if (rsrc & VGA_RSRC_LEGACY_MEM)
+		vgadev->mem_lock_cnt++;
+	if (rsrc & VGA_RSRC_NORMAL_IO)
+		vgadev->io_norm_cnt++;
+	if (rsrc & VGA_RSRC_NORMAL_MEM)
+		vgadev->mem_norm_cnt++;
+
+	return NULL;
+}
+
+static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
+{
+	struct device *dev = &vgadev->pdev->dev;
+	unsigned int old_locks = vgadev->locks;
+
+	vgaarb_dbg(dev, "%s\n", __func__);
+
+	/* Update our counters, and account for equivalent legacy resources
+	 * if we decode them
+	 */
+	if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
+		vgadev->io_norm_cnt--;
+		if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
+			rsrc |= VGA_RSRC_LEGACY_IO;
+	}
+	if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
+		vgadev->mem_norm_cnt--;
+		if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
+			rsrc |= VGA_RSRC_LEGACY_MEM;
+	}
+	if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
+		vgadev->io_lock_cnt--;
+	if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
+		vgadev->mem_lock_cnt--;
+
+	/* Just clear lock bits, we do lazy operations so we don't really
+	 * have to bother about anything else at this point
+	 */
+	if (vgadev->io_lock_cnt == 0)
+		vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
+	if (vgadev->mem_lock_cnt == 0)
+		vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
+
+	/* Kick the wait queue in case somebody was waiting if we actually
+	 * released something
+	 */
+	if (old_locks != vgadev->locks)
+		wake_up_all(&vga_wait_queue);
+}
+
+/**
+ * vga_get - acquire & locks VGA resources
+ * @pdev: pci device of the VGA card or NULL for the system default
+ * @rsrc: bit mask of resources to acquire and lock
+ * @interruptible: blocking should be interruptible by signals ?
+ *
+ * This function acquires VGA resources for the given card and mark those
+ * resources locked. If the resource requested are "normal" (and not legacy)
+ * resources, the arbiter will first check whether the card is doing legacy
+ * decoding for that type of resource. If yes, the lock is "converted" into a
+ * legacy resource lock.
+ *
+ * The arbiter will first look for all VGA cards that might conflict and disable
+ * their IOs and/or Memory access, including VGA forwarding on P2P bridges if
+ * necessary, so that the requested resources can be used. Then, the card is
+ * marked as locking these resources and the IO and/or Memory accesses are
+ * enabled on the card (including VGA forwarding on parent P2P bridges if any).
+ *
+ * This function will block if some conflicting card is already locking one of
+ * the required resources (or any resource on a different bus segment, since P2P
+ * bridges don't differentiate VGA memory and IO afaik). You can indicate
+ * whether this blocking should be interruptible by a signal (for userland
+ * interface) or not.
+ *
+ * Must not be called at interrupt time or in atomic context.  If the card
+ * already owns the resources, the function succeeds.  Nested calls are
+ * supported (a per-resource counter is maintained)
+ *
+ * On success, release the VGA resource again with vga_put().
+ *
+ * Returns:
+ *
+ * 0 on success, negative error code on failure.
+ */
+int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
+{
+	struct vga_device *vgadev, *conflict;
+	unsigned long flags;
+	wait_queue_entry_t wait;
+	int rc = 0;
+
+	vga_check_first_use();
+	/* The one who calls us should check for this, but lets be sure... */
+	if (pdev == NULL)
+		pdev = vga_default_device();
+	if (pdev == NULL)
+		return 0;
+
+	for (;;) {
+		spin_lock_irqsave(&vga_lock, flags);
+		vgadev = vgadev_find(pdev);
+		if (vgadev == NULL) {
+			spin_unlock_irqrestore(&vga_lock, flags);
+			rc = -ENODEV;
+			break;
+		}
+		conflict = __vga_tryget(vgadev, rsrc);
+		spin_unlock_irqrestore(&vga_lock, flags);
+		if (conflict == NULL)
+			break;
+
+
+		/* We have a conflict, we wait until somebody kicks the
+		 * work queue. Currently we have one work queue that we
+		 * kick each time some resources are released, but it would
+		 * be fairly easy to have a per device one so that we only
+		 * need to attach to the conflicting device
+		 */
+		init_waitqueue_entry(&wait, current);
+		add_wait_queue(&vga_wait_queue, &wait);
+		set_current_state(interruptible ?
+				  TASK_INTERRUPTIBLE :
+				  TASK_UNINTERRUPTIBLE);
+		if (interruptible && signal_pending(current)) {
+			__set_current_state(TASK_RUNNING);
+			remove_wait_queue(&vga_wait_queue, &wait);
+			rc = -ERESTARTSYS;
+			break;
+		}
+		schedule();
+		remove_wait_queue(&vga_wait_queue, &wait);
+	}
+	return rc;
+}
+EXPORT_SYMBOL(vga_get);
+
+/**
+ * vga_tryget - try to acquire & lock legacy VGA resources
+ * @pdev: pci devivce of VGA card or NULL for system default
+ * @rsrc: bit mask of resources to acquire and lock
+ *
+ * This function performs the same operation as vga_get(), but will return an
+ * error (-EBUSY) instead of blocking if the resources are already locked by
+ * another card. It can be called in any context
+ *
+ * On success, release the VGA resource again with vga_put().
+ *
+ * Returns:
+ *
+ * 0 on success, negative error code on failure.
+ */
+int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
+{
+	struct vga_device *vgadev;
+	unsigned long flags;
+	int rc = 0;
+
+	vga_check_first_use();
+
+	/* The one who calls us should check for this, but lets be sure... */
+	if (pdev == NULL)
+		pdev = vga_default_device();
+	if (pdev == NULL)
+		return 0;
+	spin_lock_irqsave(&vga_lock, flags);
+	vgadev = vgadev_find(pdev);
+	if (vgadev == NULL) {
+		rc = -ENODEV;
+		goto bail;
+	}
+	if (__vga_tryget(vgadev, rsrc))
+		rc = -EBUSY;
+bail:
+	spin_unlock_irqrestore(&vga_lock, flags);
+	return rc;
+}
+EXPORT_SYMBOL(vga_tryget);
+
+/**
+ * vga_put - release lock on legacy VGA resources
+ * @pdev: pci device of VGA card or NULL for system default
+ * @rsrc: but mask of resource to release
+ *
+ * This fuction releases resources previously locked by vga_get() or
+ * vga_tryget(). The resources aren't disabled right away, so that a subsequence
+ * vga_get() on the same card will succeed immediately. Resources have a
+ * counter, so locks are only released if the counter reaches 0.
+ */
+void vga_put(struct pci_dev *pdev, unsigned int rsrc)
+{
+	struct vga_device *vgadev;
+	unsigned long flags;
+
+	/* The one who calls us should check for this, but lets be sure... */
+	if (pdev == NULL)
+		pdev = vga_default_device();
+	if (pdev == NULL)
+		return;
+	spin_lock_irqsave(&vga_lock, flags);
+	vgadev = vgadev_find(pdev);
+	if (vgadev == NULL)
+		goto bail;
+	__vga_put(vgadev, rsrc);
+bail:
+	spin_unlock_irqrestore(&vga_lock, flags);
+}
+EXPORT_SYMBOL(vga_put);
+
+/*
+ * Rules for using a bridge to control a VGA descendant decoding: if a bridge
+ * has only one VGA descendant then it can be used to control the VGA routing
+ * for that device. It should always use the bridge closest to the device to
+ * control it. If a bridge has a direct VGA descendant, but also have a sub-
+ * bridge VGA descendant then we cannot use that bridge to control the direct
+ * VGA descendant. So for every device we register, we need to iterate all
+ * its parent bridges so we can invalidate any devices using them properly.
+ */
+static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
+{
+	struct vga_device *same_bridge_vgadev;
+	struct pci_bus *new_bus, *bus;
+	struct pci_dev *new_bridge, *bridge;
+
+	vgadev->bridge_has_one_vga = true;
+
+	if (list_empty(&vga_list))
+		return;
+
+	/* okay iterate the new devices bridge hierarachy */
+	new_bus = vgadev->pdev->bus;
+	while (new_bus) {
+		new_bridge = new_bus->self;
+
+		/* go through list of devices already registered */
+		list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
+			bus = same_bridge_vgadev->pdev->bus;
+			bridge = bus->self;
+
+			/* see if the share a bridge with this device */
+			if (new_bridge == bridge) {
+				/*
+				 * If their direct parent bridge is the same
+				 * as any bridge of this device then it can't
+				 * be used for that device.
+				 */
+				same_bridge_vgadev->bridge_has_one_vga = false;
+			}
+
+			/*
+			 * Now iterate the previous devices bridge hierarchy.
+			 * If the new devices parent bridge is in the other
+			 * devices hierarchy then we can't use it to control
+			 * this device
+			 */
+			while (bus) {
+				bridge = bus->self;
+
+				if (bridge && bridge == vgadev->pdev->bus->self)
+					vgadev->bridge_has_one_vga = false;
+
+				bus = bus->parent;
+			}
+		}
+		new_bus = new_bus->parent;
+	}
+}
+
+/*
+ * Currently, we assume that the "initial" setup of the system is
+ * not sane, that is we come up with conflicting devices and let
+ * the arbiter's client decides if devices decodes or not legacy
+ * things.
+ */
+static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
+{
+	struct vga_device *vgadev;
+	unsigned long flags;
+	struct pci_bus *bus;
+	struct pci_dev *bridge;
+	u16 cmd;
+
+	/* Only deal with VGA class devices */
+	if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
+		return false;
+
+	/* Allocate structure */
+	vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
+	if (vgadev == NULL) {
+		vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
+		/*
+		 * What to do on allocation failure ? For now, let's just do
+		 * nothing, I'm not sure there is anything saner to be done.
+		 */
+		return false;
+	}
+
+	/* Take lock & check for duplicates */
+	spin_lock_irqsave(&vga_lock, flags);
+	if (vgadev_find(pdev) != NULL) {
+		BUG_ON(1);
+		goto fail;
+	}
+	vgadev->pdev = pdev;
+
+	/* By default, assume we decode everything */
+	vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
+			  VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+
+	/* by default mark it as decoding */
+	vga_decode_count++;
+	/* Mark that we "own" resources based on our enables, we will
+	 * clear that below if the bridge isn't forwarding
+	 */
+	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
+	if (cmd & PCI_COMMAND_IO)
+		vgadev->owns |= VGA_RSRC_LEGACY_IO;
+	if (cmd & PCI_COMMAND_MEMORY)
+		vgadev->owns |= VGA_RSRC_LEGACY_MEM;
+
+	/* Check if VGA cycles can get down to us */
+	bus = pdev->bus;
+	while (bus) {
+		bridge = bus->self;
+		if (bridge) {
+			u16 l;
+
+			pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l);
+			if (!(l & PCI_BRIDGE_CTL_VGA)) {
+				vgadev->owns = 0;
+				break;
+			}
+		}
+		bus = bus->parent;
+	}
+
+	/* Deal with VGA default device. Use first enabled one
+	 * by default if arch doesn't have it's own hook
+	 */
+	if (vga_default == NULL &&
+	    ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {
+		vgaarb_info(&pdev->dev, "setting as boot VGA device\n");
+		vga_set_default_device(pdev);
+	}
+
+	vga_arbiter_check_bridge_sharing(vgadev);
+
+	/* Add to the list */
+	list_add(&vgadev->list, &vga_list);
+	vga_count++;
+	vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
+		vga_iostate_to_str(vgadev->decodes),
+		vga_iostate_to_str(vgadev->owns),
+		vga_iostate_to_str(vgadev->locks));
+
+	spin_unlock_irqrestore(&vga_lock, flags);
+	return true;
+fail:
+	spin_unlock_irqrestore(&vga_lock, flags);
+	kfree(vgadev);
+	return false;
+}
+
+static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
+{
+	struct vga_device *vgadev;
+	unsigned long flags;
+	bool ret = true;
+
+	spin_lock_irqsave(&vga_lock, flags);
+	vgadev = vgadev_find(pdev);
+	if (vgadev == NULL) {
+		ret = false;
+		goto bail;
+	}
+
+	if (vga_default == pdev)
+		vga_set_default_device(NULL);
+
+	if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
+		vga_decode_count--;
+
+	/* Remove entry from list */
+	list_del(&vgadev->list);
+	vga_count--;
+	/* Notify userland driver that the device is gone so it discards
+	 * it's copies of the pci_dev pointer
+	 */
+	vga_arb_device_card_gone(pdev);
+
+	/* Wake up all possible waiters */
+	wake_up_all(&vga_wait_queue);
+bail:
+	spin_unlock_irqrestore(&vga_lock, flags);
+	kfree(vgadev);
+	return ret;
+}
+
+/* this is called with the lock */
+static inline void vga_update_device_decodes(struct vga_device *vgadev,
+					     int new_decodes)
+{
+	struct device *dev = &vgadev->pdev->dev;
+	int old_decodes, decodes_removed, decodes_unlocked;
+
+	old_decodes = vgadev->decodes;
+	decodes_removed = ~new_decodes & old_decodes;
+	decodes_unlocked = vgadev->locks & decodes_removed;
+	vgadev->decodes = new_decodes;
+
+	vgaarb_info(dev, "changed VGA decodes: olddecodes=%s,decodes=%s:owns=%s\n",
+		vga_iostate_to_str(old_decodes),
+		vga_iostate_to_str(vgadev->decodes),
+		vga_iostate_to_str(vgadev->owns));
+
+	/* if we removed locked decodes, lock count goes to zero, and release */
+	if (decodes_unlocked) {
+		if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
+			vgadev->io_lock_cnt = 0;
+		if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
+			vgadev->mem_lock_cnt = 0;
+		__vga_put(vgadev, decodes_unlocked);
+	}
+
+	/* change decodes counter */
+	if (old_decodes & VGA_RSRC_LEGACY_MASK &&
+	    !(new_decodes & VGA_RSRC_LEGACY_MASK))
+		vga_decode_count--;
+	if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
+	    new_decodes & VGA_RSRC_LEGACY_MASK)
+		vga_decode_count++;
+	vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
+}
+
+static void __vga_set_legacy_decoding(struct pci_dev *pdev,
+				      unsigned int decodes,
+				      bool userspace)
+{
+	struct vga_device *vgadev;
+	unsigned long flags;
+
+	decodes &= VGA_RSRC_LEGACY_MASK;
+
+	spin_lock_irqsave(&vga_lock, flags);
+	vgadev = vgadev_find(pdev);
+	if (vgadev == NULL)
+		goto bail;
+
+	/* don't let userspace futz with kernel driver decodes */
+	if (userspace && vgadev->set_vga_decode)
+		goto bail;
+
+	/* update the device decodes + counter */
+	vga_update_device_decodes(vgadev, decodes);
+
+	/* XXX if somebody is going from "doesn't decode" to "decodes" state
+	 * here, additional care must be taken as we may have pending owner
+	 * ship of non-legacy region ...
+	 */
+bail:
+	spin_unlock_irqrestore(&vga_lock, flags);
+}
+
+void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
+{
+	__vga_set_legacy_decoding(pdev, decodes, false);
+}
+EXPORT_SYMBOL(vga_set_legacy_decoding);
+
+/**
+ * vga_client_register - register or unregister a VGA arbitration client
+ * @pdev: pci device of the VGA client
+ * @cookie: client cookie to be used in callbacks
+ * @irq_set_state: irq state change callback
+ * @set_vga_decode: vga decode change callback
+ *
+ * Clients have two callback mechanisms they can use.
+ *
+ * @irq_set_state callback: If a client can't disable its GPUs VGA
+ * resources, then we need to be able to ask it to turn off its irqs when we
+ * turn off its mem and io decoding.
+ *
+ * @set_vga_decode callback: If a client can disable its GPU VGA resource, it
+ * will get a callback from this to set the encode/decode state.
+ *
+ * Rationale: we cannot disable VGA decode resources unconditionally some single
+ * GPU laptops seem to require ACPI or BIOS access to the VGA registers to
+ * control things like backlights etc.  Hopefully newer multi-GPU laptops do
+ * something saner, and desktops won't have any special ACPI for this. The
+ * driver will get a callback when VGA arbitration is first used by userspace
+ * since some older X servers have issues.
+ *
+ * This function does not check whether a client for @pdev has been registered
+ * already.
+ *
+ * To unregister just call this function with @irq_set_state and @set_vga_decode
+ * both set to NULL for the same @pdev as originally used to register them.
+ *
+ * Returns: 0 on success, -1 on failure
+ */
+int vga_client_register(struct pci_dev *pdev, void *cookie,
+			void (*irq_set_state)(void *cookie, bool state),
+			unsigned int (*set_vga_decode)(void *cookie,
+						       bool decode))
+{
+	int ret = -ENODEV;
+	struct vga_device *vgadev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vga_lock, flags);
+	vgadev = vgadev_find(pdev);
+	if (!vgadev)
+		goto bail;
+
+	vgadev->irq_set_state = irq_set_state;
+	vgadev->set_vga_decode = set_vga_decode;
+	vgadev->cookie = cookie;
+	ret = 0;
+
+bail:
+	spin_unlock_irqrestore(&vga_lock, flags);
+	return ret;
+
+}
+EXPORT_SYMBOL(vga_client_register);
+
+/*
+ * Char driver implementation
+ *
+ * Semantics is:
+ *
+ *  open       : open user instance of the arbitrer. by default, it's
+ *                attached to the default VGA device of the system.
+ *
+ *  close      : close user instance, release locks
+ *
+ *  read       : return a string indicating the status of the target.
+ *                an IO state string is of the form {io,mem,io+mem,none},
+ *                mc and ic are respectively mem and io lock counts (for
+ *                debugging/diagnostic only). "decodes" indicate what the
+ *                card currently decodes, "owns" indicates what is currently
+ *                enabled on it, and "locks" indicates what is locked by this
+ *                card. If the card is unplugged, we get "invalid" then for
+ *                card_ID and an -ENODEV error is returned for any command
+ *                until a new card is targeted
+ *
+ *   "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
+ *
+ * write       : write a command to the arbiter. List of commands is:
+ *
+ *   target <card_ID>   : switch target to card <card_ID> (see below)
+ *   lock <io_state>    : acquires locks on target ("none" is invalid io_state)
+ *   trylock <io_state> : non-blocking acquire locks on target
+ *   unlock <io_state>  : release locks on target
+ *   unlock all         : release all locks on target held by this user
+ *   decodes <io_state> : set the legacy decoding attributes for the card
+ *
+ * poll         : event if something change on any card (not just the target)
+ *
+ * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
+ * to go back to the system default card (TODO: not implemented yet).
+ * Currently, only PCI is supported as a prefix, but the userland API may
+ * support other bus types in the future, even if the current kernel
+ * implementation doesn't.
+ *
+ * Note about locks:
+ *
+ * The driver keeps track of which user has what locks on which card. It
+ * supports stacking, like the kernel one. This complexifies the implementation
+ * a bit, but makes the arbiter more tolerant to userspace problems and able
+ * to properly cleanup in all cases when a process dies.
+ * Currently, a max of 16 cards simultaneously can have locks issued from
+ * userspace for a given user (file descriptor instance) of the arbiter.
+ *
+ * If the device is hot-unplugged, there is a hook inside the module to notify
+ * they being added/removed in the system and automatically added/removed in
+ * the arbiter.
+ */
+
+#define MAX_USER_CARDS         CONFIG_VGA_ARB_MAX_GPUS
+#define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
+
+/*
+ * Each user has an array of these, tracking which cards have locks
+ */
+struct vga_arb_user_card {
+	struct pci_dev *pdev;
+	unsigned int mem_cnt;
+	unsigned int io_cnt;
+};
+
+struct vga_arb_private {
+	struct list_head list;
+	struct pci_dev *target;
+	struct vga_arb_user_card cards[MAX_USER_CARDS];
+	spinlock_t lock;
+};
+
+static LIST_HEAD(vga_user_list);
+static DEFINE_SPINLOCK(vga_user_lock);
+
+
+/*
+ * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
+ * returns the respective values. If the string is not in this format,
+ * it returns 0.
+ */
+static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
+			       unsigned int *bus, unsigned int *devfn)
+{
+	int n;
+	unsigned int slot, func;
+
+
+	n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
+	if (n != 4)
+		return 0;
+
+	*devfn = PCI_DEVFN(slot, func);
+
+	return 1;
+}
+
+static ssize_t vga_arb_read(struct file *file, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	struct vga_arb_private *priv = file->private_data;
+	struct vga_device *vgadev;
+	struct pci_dev *pdev;
+	unsigned long flags;
+	size_t len;
+	int rc;
+	char *lbuf;
+
+	lbuf = kmalloc(1024, GFP_KERNEL);
+	if (lbuf == NULL)
+		return -ENOMEM;
+
+	/* Shields against vga_arb_device_card_gone (pci_dev going
+	 * away), and allows access to vga list
+	 */
+	spin_lock_irqsave(&vga_lock, flags);
+
+	/* If we are targeting the default, use it */
+	pdev = priv->target;
+	if (pdev == NULL || pdev == PCI_INVALID_CARD) {
+		spin_unlock_irqrestore(&vga_lock, flags);
+		len = sprintf(lbuf, "invalid");
+		goto done;
+	}
+
+	/* Find card vgadev structure */
+	vgadev = vgadev_find(pdev);
+	if (vgadev == NULL) {
+		/* Wow, it's not in the list, that shouldn't happen,
+		 * let's fix us up and return invalid card
+		 */
+		if (pdev == priv->target)
+			vga_arb_device_card_gone(pdev);
+		spin_unlock_irqrestore(&vga_lock, flags);
+		len = sprintf(lbuf, "invalid");
+		goto done;
+	}
+
+	/* Fill the buffer with infos */
+	len = snprintf(lbuf, 1024,
+		       "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
+		       vga_decode_count, pci_name(pdev),
+		       vga_iostate_to_str(vgadev->decodes),
+		       vga_iostate_to_str(vgadev->owns),
+		       vga_iostate_to_str(vgadev->locks),
+		       vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
+
+	spin_unlock_irqrestore(&vga_lock, flags);
+done:
+
+	/* Copy that to user */
+	if (len > count)
+		len = count;
+	rc = copy_to_user(buf, lbuf, len);
+	kfree(lbuf);
+	if (rc)
+		return -EFAULT;
+	return len;
+}
+
+/*
+ * TODO: To avoid parsing inside kernel and to improve the speed we may
+ * consider use ioctl here
+ */
+static ssize_t vga_arb_write(struct file *file, const char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	struct vga_arb_private *priv = file->private_data;
+	struct vga_arb_user_card *uc = NULL;
+	struct pci_dev *pdev;
+
+	unsigned int io_state;
+
+	char kbuf[64], *curr_pos;
+	size_t remaining = count;
+
+	int ret_val;
+	int i;
+
+	if (count >= sizeof(kbuf))
+		return -EINVAL;
+	if (copy_from_user(kbuf, buf, count))
+		return -EFAULT;
+	curr_pos = kbuf;
+	kbuf[count] = '\0';	/* Just to make sure... */
+
+	if (strncmp(curr_pos, "lock ", 5) == 0) {
+		curr_pos += 5;
+		remaining -= 5;
+
+		pr_debug("client 0x%p called 'lock'\n", priv);
+
+		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
+			ret_val = -EPROTO;
+			goto done;
+		}
+		if (io_state == VGA_RSRC_NONE) {
+			ret_val = -EPROTO;
+			goto done;
+		}
+
+		pdev = priv->target;
+		if (priv->target == NULL) {
+			ret_val = -ENODEV;
+			goto done;
+		}
+
+		vga_get_uninterruptible(pdev, io_state);
+
+		/* Update the client's locks lists... */
+		for (i = 0; i < MAX_USER_CARDS; i++) {
+			if (priv->cards[i].pdev == pdev) {
+				if (io_state & VGA_RSRC_LEGACY_IO)
+					priv->cards[i].io_cnt++;
+				if (io_state & VGA_RSRC_LEGACY_MEM)
+					priv->cards[i].mem_cnt++;
+				break;
+			}
+		}
+
+		ret_val = count;
+		goto done;
+	} else if (strncmp(curr_pos, "unlock ", 7) == 0) {
+		curr_pos += 7;
+		remaining -= 7;
+
+		pr_debug("client 0x%p called 'unlock'\n", priv);
+
+		if (strncmp(curr_pos, "all", 3) == 0)
+			io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
+		else {
+			if (!vga_str_to_iostate
+			    (curr_pos, remaining, &io_state)) {
+				ret_val = -EPROTO;
+				goto done;
+			}
+			/* TODO: Add this?
+			   if (io_state == VGA_RSRC_NONE) {
+			   ret_val = -EPROTO;
+			   goto done;
+			   }
+			  */
+		}
+
+		pdev = priv->target;
+		if (priv->target == NULL) {
+			ret_val = -ENODEV;
+			goto done;
+		}
+		for (i = 0; i < MAX_USER_CARDS; i++) {
+			if (priv->cards[i].pdev == pdev)
+				uc = &priv->cards[i];
+		}
+
+		if (!uc) {
+			ret_val = -EINVAL;
+			goto done;
+		}
+
+		if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {
+			ret_val = -EINVAL;
+			goto done;
+		}
+
+		if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {
+			ret_val = -EINVAL;
+			goto done;
+		}
+
+		vga_put(pdev, io_state);
+
+		if (io_state & VGA_RSRC_LEGACY_IO)
+			uc->io_cnt--;
+		if (io_state & VGA_RSRC_LEGACY_MEM)
+			uc->mem_cnt--;
+
+		ret_val = count;
+		goto done;
+	} else if (strncmp(curr_pos, "trylock ", 8) == 0) {
+		curr_pos += 8;
+		remaining -= 8;
+
+		pr_debug("client 0x%p called 'trylock'\n", priv);
+
+		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
+			ret_val = -EPROTO;
+			goto done;
+		}
+		/* TODO: Add this?
+		   if (io_state == VGA_RSRC_NONE) {
+		   ret_val = -EPROTO;
+		   goto done;
+		   }
+		 */
+
+		pdev = priv->target;
+		if (priv->target == NULL) {
+			ret_val = -ENODEV;
+			goto done;
+		}
+
+		if (vga_tryget(pdev, io_state)) {
+			/* Update the client's locks lists... */
+			for (i = 0; i < MAX_USER_CARDS; i++) {
+				if (priv->cards[i].pdev == pdev) {
+					if (io_state & VGA_RSRC_LEGACY_IO)
+						priv->cards[i].io_cnt++;
+					if (io_state & VGA_RSRC_LEGACY_MEM)
+						priv->cards[i].mem_cnt++;
+					break;
+				}
+			}
+			ret_val = count;
+			goto done;
+		} else {
+			ret_val = -EBUSY;
+			goto done;
+		}
+
+	} else if (strncmp(curr_pos, "target ", 7) == 0) {
+		unsigned int domain, bus, devfn;
+		struct vga_device *vgadev;
+
+		curr_pos += 7;
+		remaining -= 7;
+		pr_debug("client 0x%p called 'target'\n", priv);
+		/* if target is default */
+		if (!strncmp(curr_pos, "default", 7))
+			pdev = pci_dev_get(vga_default_device());
+		else {
+			if (!vga_pci_str_to_vars(curr_pos, remaining,
+						 &domain, &bus, &devfn)) {
+				ret_val = -EPROTO;
+				goto done;
+			}
+			pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
+			if (!pdev) {
+				pr_debug("invalid PCI address %04x:%02x:%02x.%x\n",
+					 domain, bus, PCI_SLOT(devfn),
+					 PCI_FUNC(devfn));
+				ret_val = -ENODEV;
+				goto done;
+			}
+
+			pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos,
+				domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
+				pdev);
+		}
+
+		vgadev = vgadev_find(pdev);
+		pr_debug("vgadev %p\n", vgadev);
+		if (vgadev == NULL) {
+			if (pdev) {
+				vgaarb_dbg(&pdev->dev, "not a VGA device\n");
+				pci_dev_put(pdev);
+			}
+
+			ret_val = -ENODEV;
+			goto done;
+		}
+
+		priv->target = pdev;
+		for (i = 0; i < MAX_USER_CARDS; i++) {
+			if (priv->cards[i].pdev == pdev)
+				break;
+			if (priv->cards[i].pdev == NULL) {
+				priv->cards[i].pdev = pdev;
+				priv->cards[i].io_cnt = 0;
+				priv->cards[i].mem_cnt = 0;
+				break;
+			}
+		}
+		if (i == MAX_USER_CARDS) {
+			vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",
+				MAX_USER_CARDS);
+			pci_dev_put(pdev);
+			/* XXX: which value to return? */
+			ret_val =  -ENOMEM;
+			goto done;
+		}
+
+		ret_val = count;
+		pci_dev_put(pdev);
+		goto done;
+
+
+	} else if (strncmp(curr_pos, "decodes ", 8) == 0) {
+		curr_pos += 8;
+		remaining -= 8;
+		pr_debug("client 0x%p called 'decodes'\n", priv);
+
+		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
+			ret_val = -EPROTO;
+			goto done;
+		}
+		pdev = priv->target;
+		if (priv->target == NULL) {
+			ret_val = -ENODEV;
+			goto done;
+		}
+
+		__vga_set_legacy_decoding(pdev, io_state, true);
+		ret_val = count;
+		goto done;
+	}
+	/* If we got here, the message written is not part of the protocol! */
+	return -EPROTO;
+
+done:
+	return ret_val;
+}
+
+static __poll_t vga_arb_fpoll(struct file *file, poll_table *wait)
+{
+	pr_debug("%s\n", __func__);
+
+	poll_wait(file, &vga_wait_queue, wait);
+	return EPOLLIN;
+}
+
+static int vga_arb_open(struct inode *inode, struct file *file)
+{
+	struct vga_arb_private *priv;
+	unsigned long flags;
+
+	pr_debug("%s\n", __func__);
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (priv == NULL)
+		return -ENOMEM;
+	spin_lock_init(&priv->lock);
+	file->private_data = priv;
+
+	spin_lock_irqsave(&vga_user_lock, flags);
+	list_add(&priv->list, &vga_user_list);
+	spin_unlock_irqrestore(&vga_user_lock, flags);
+
+	/* Set the client' lists of locks */
+	priv->target = vga_default_device(); /* Maybe this is still null! */
+	priv->cards[0].pdev = priv->target;
+	priv->cards[0].io_cnt = 0;
+	priv->cards[0].mem_cnt = 0;
+
+
+	return 0;
+}
+
+static int vga_arb_release(struct inode *inode, struct file *file)
+{
+	struct vga_arb_private *priv = file->private_data;
+	struct vga_arb_user_card *uc;
+	unsigned long flags;
+	int i;
+
+	pr_debug("%s\n", __func__);
+
+	spin_lock_irqsave(&vga_user_lock, flags);
+	list_del(&priv->list);
+	for (i = 0; i < MAX_USER_CARDS; i++) {
+		uc = &priv->cards[i];
+		if (uc->pdev == NULL)
+			continue;
+		vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",
+			uc->io_cnt, uc->mem_cnt);
+		while (uc->io_cnt--)
+			vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
+		while (uc->mem_cnt--)
+			vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
+	}
+	spin_unlock_irqrestore(&vga_user_lock, flags);
+
+	kfree(priv);
+
+	return 0;
+}
+
+static void vga_arb_device_card_gone(struct pci_dev *pdev)
+{
+}
+
+/*
+ * callback any registered clients to let them know we have a
+ * change in VGA cards
+ */
+static void vga_arbiter_notify_clients(void)
+{
+	struct vga_device *vgadev;
+	unsigned long flags;
+	uint32_t new_decodes;
+	bool new_state;
+
+	if (!vga_arbiter_used)
+		return;
+
+	spin_lock_irqsave(&vga_lock, flags);
+	list_for_each_entry(vgadev, &vga_list, list) {
+		if (vga_count > 1)
+			new_state = false;
+		else
+			new_state = true;
+		if (vgadev->set_vga_decode) {
+			new_decodes = vgadev->set_vga_decode(vgadev->cookie,
+							     new_state);
+			vga_update_device_decodes(vgadev, new_decodes);
+		}
+	}
+	spin_unlock_irqrestore(&vga_lock, flags);
+}
+
+static int pci_notify(struct notifier_block *nb, unsigned long action,
+		      void *data)
+{
+	struct device *dev = data;
+	struct pci_dev *pdev = to_pci_dev(dev);
+	bool notify = false;
+
+	vgaarb_dbg(dev, "%s\n", __func__);
+
+	/* For now we're only intereted in devices added and removed. I didn't
+	 * test this thing here, so someone needs to double check for the
+	 * cases of hotplugable vga cards. */
+	if (action == BUS_NOTIFY_ADD_DEVICE)
+		notify = vga_arbiter_add_pci_device(pdev);
+	else if (action == BUS_NOTIFY_DEL_DEVICE)
+		notify = vga_arbiter_del_pci_device(pdev);
+
+	if (notify)
+		vga_arbiter_notify_clients();
+	return 0;
+}
+
+static struct notifier_block pci_notifier = {
+	.notifier_call = pci_notify,
+};
+
+static const struct file_operations vga_arb_device_fops = {
+	.read = vga_arb_read,
+	.write = vga_arb_write,
+	.poll = vga_arb_fpoll,
+	.open = vga_arb_open,
+	.release = vga_arb_release,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice vga_arb_device = {
+	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
+};
+
+static void __init vga_arb_select_default_device(void)
+{
+	struct pci_dev *pdev;
+	struct vga_device *vgadev;
+
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
+	list_for_each_entry(vgadev, &vga_list, list) {
+		struct device *dev = &vgadev->pdev->dev;
+		/*
+		 * Override vga_arbiter_add_pci_device()'s I/O based detection
+		 * as it may take the wrong device (e.g. on Apple system under
+		 * EFI).
+		 *
+		 * Select the device owning the boot framebuffer if there is
+		 * one.
+		 */
+		resource_size_t start, end, limit;
+		unsigned long flags;
+		int i;
+
+		limit = screen_info.lfb_base + screen_info.lfb_size;
+
+		/* Does firmware framebuffer belong to us? */
+		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
+			flags = pci_resource_flags(vgadev->pdev, i);
+
+			if ((flags & IORESOURCE_MEM) == 0)
+				continue;
+
+			start = pci_resource_start(vgadev->pdev, i);
+			end  = pci_resource_end(vgadev->pdev, i);
+
+			if (!start || !end)
+				continue;
+
+			if (screen_info.lfb_base < start || limit >= end)
+				continue;
+
+			if (!vga_default_device())
+				vgaarb_info(dev, "setting as boot device\n");
+			else if (vgadev->pdev != vga_default_device())
+				vgaarb_info(dev, "overriding boot device\n");
+			vga_set_default_device(vgadev->pdev);
+		}
+	}
+#endif
+
+	if (!vga_default_device()) {
+		list_for_each_entry(vgadev, &vga_list, list) {
+			struct device *dev = &vgadev->pdev->dev;
+			u16 cmd;
+
+			pdev = vgadev->pdev;
+			pci_read_config_word(pdev, PCI_COMMAND, &cmd);
+			if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
+				vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");
+				vga_set_default_device(pdev);
+				break;
+			}
+		}
+	}
+
+	if (!vga_default_device()) {
+		vgadev = list_first_entry_or_null(&vga_list,
+						  struct vga_device, list);
+		if (vgadev) {
+			struct device *dev = &vgadev->pdev->dev;
+			vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");
+			vga_set_default_device(vgadev->pdev);
+		}
+	}
+}
+
+static int __init vga_arb_device_init(void)
+{
+	int rc;
+	struct pci_dev *pdev;
+	struct vga_device *vgadev;
+
+	rc = misc_register(&vga_arb_device);
+	if (rc < 0)
+		pr_err("error %d registering device\n", rc);
+
+	bus_register_notifier(&pci_bus_type, &pci_notifier);
+
+	/* We add all PCI devices satisfying VGA class in the arbiter by
+	 * default */
+	pdev = NULL;
+	while ((pdev =
+		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+			       PCI_ANY_ID, pdev)) != NULL)
+		vga_arbiter_add_pci_device(pdev);
+
+	list_for_each_entry(vgadev, &vga_list, list) {
+		struct device *dev = &vgadev->pdev->dev;
+
+		if (vgadev->bridge_has_one_vga)
+			vgaarb_info(dev, "bridge control possible\n");
+		else
+			vgaarb_info(dev, "no bridge control possible\n");
+	}
+
+	vga_arb_select_default_device();
+
+	pr_info("loaded\n");
+	return rc;
+}
+subsys_initcall(vga_arb_device_init);