text: /*
   *  Copyright (C) 2015       Red Hat Inc.
   *                           Hans de Goede <hdegoede@redhat.com>
   *  Copyright (C) 2008       SuSE Linux Products GmbH
   *                           Thomas Renninger <trenn@suse.de>
   *
   *  May be copied or modified under the terms of the GNU General Public License
   *
   * video_detect.c:
   * After PCI devices are glued with ACPI devices
   * acpi_get_pci_dev() can be called to identify ACPI graphics
   * devices for which a real graphics card is plugged in
   *
   * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
   * are available, video.ko should be used to handle the device.
   *
   * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
   * sony_acpi,... can take care about backlight brightness.
   *
   * Backlight drivers can use acpi_video_get_backlight_type() to determine
   * which driver should handle the backlight.
   *
   * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
   * this file will not be compiled and acpi_video_get_backlight_type() will
   * always return acpi_backlight_vendor.
   */
  
  #include <linux/export.h>
  #include <linux/acpi.h>
  #include <linux/backlight.h>
  #include <linux/dmi.h>
  #include <linux/module.h>
  #include <linux/pci.h>
  #include <linux/types.h>
  #include <linux/workqueue.h>
  #include <acpi/video.h>
  
  ACPI_MODULE_NAME("video");
  #define _COMPONENT		ACPI_VIDEO_COMPONENT
  
  void acpi_video_unregister_backlight(void);
  
  static bool backlight_notifier_registered;
  static struct notifier_block backlight_nb;
  static struct work_struct backlight_notify_work;
  
  static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;
  static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;
  
  static void acpi_video_parse_cmdline(void)
  {
  	if (!strcmp("vendor", acpi_video_backlight_string))
  		acpi_backlight_cmdline = acpi_backlight_vendor;
  	if (!strcmp("video", acpi_video_backlight_string))
  		acpi_backlight_cmdline = acpi_backlight_video;
  	if (!strcmp("native", acpi_video_backlight_string))
  		acpi_backlight_cmdline = acpi_backlight_native;
  	if (!strcmp("none", acpi_video_backlight_string))
  		acpi_backlight_cmdline = acpi_backlight_none;
  }
  
  static acpi_status
  find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
  {
  	long *cap = context;
  	struct pci_dev *dev;
  	struct acpi_device *acpi_dev;
  
  	static const struct acpi_device_id video_ids[] = {
  		{ACPI_VIDEO_HID, 0},
  		{"", 0},
  	};
  	if (acpi_bus_get_device(handle, &acpi_dev))
  		return AE_OK;
  
  	if (!acpi_match_device_ids(acpi_dev, video_ids)) {
  		dev = acpi_get_pci_dev(handle);
  		if (!dev)
  			return AE_OK;
  		pci_dev_put(dev);
  		*cap |= acpi_is_video_device(handle);
  	}
  	return AE_OK;
  }
  
  /* Force to use vendor driver when the ACPI device is known to be
   * buggy */
  static int video_detect_force_vendor(const struct dmi_system_id *d)
  {
  	acpi_backlight_dmi = acpi_backlight_vendor;
  	return 0;
  }
  
  static int video_detect_force_video(const struct dmi_system_id *d)
  {
  	acpi_backlight_dmi = acpi_backlight_video;
  	return 0;
  }
  
  static int video_detect_force_native(const struct dmi_system_id *d)
  {
  	acpi_backlight_dmi = acpi_backlight_native;
  	return 0;
  }
  
  static const struct dmi_system_id video_detect_dmi_table[] = {
  	/* On Samsung X360, the BIOS will set a flag (VDRV) if generic
  	 * ACPI backlight device is used. This flag will definitively break
  	 * the backlight interface (even the vendor interface) untill next
  	 * reboot. It's why we should prevent video.ko from being used here
  	 * and we can't rely on a later call to acpi_video_unregister().
  	 */
  	{
  	 .callback = video_detect_force_vendor,
  	 .ident = "X360",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "X360"),
  		DMI_MATCH(DMI_BOARD_NAME, "X360"),
  		},
  	},
  	{
  	.callback = video_detect_force_vendor,
  	.ident = "Asus UL30VT",
  	.matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "UL30VT"),
  		},
  	},
  	{
  	.callback = video_detect_force_vendor,
  	.ident = "Asus UL30A",
  	.matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "UL30A"),
  		},
  	},
  
  	/*
  	 * These models have a working acpi_video backlight control, and using
  	 * native backlight causes a regression where backlight does not work
  	 * when userspace is not handling brightness key events. Disable
  	 * native_backlight on these to fix this:
  	 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
  	 */
  	{
  	 .callback = video_detect_force_video,
  	 .ident = "ThinkPad T420",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
  		},
  	},
  	{
  	 .callback = video_detect_force_video,
  	 .ident = "ThinkPad T520",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
  		},
  	},
  	{
  	 .callback = video_detect_force_video,
  	 .ident = "ThinkPad X201s",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
  		},
  	},
          {
           .callback = video_detect_force_video,
           .ident = "ThinkPad X201T",
           .matches = {
                  DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                  DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201T"),
                  },
          },
  
  	/* The native backlight controls do not work on some older machines */
  	{
  	 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
  	 .callback = video_detect_force_video,
  	 .ident = "HP ENVY 15 Notebook",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
  		},
  	},
  	{
  	 .callback = video_detect_force_video,
  	 .ident = "SAMSUNG 870Z5E/880Z5E/680Z5E",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
  		},
  	},
  	{
  	 .callback = video_detect_force_video,
  	 .ident = "SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME,
  			  "370R4E/370R4V/370R5E/3570RE/370R5V"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1186097 */
  	 .callback = video_detect_force_video,
  	 .ident = "SAMSUNG 3570R/370R/470R/450R/510R/4450RV",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME,
  			  "3570R/370R/470R/450R/510R/4450RV"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1094948 */
  	 .callback = video_detect_force_video,
  	 .ident = "SAMSUNG 730U3E/740U3E",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
  		},
  	},
  	{
  	 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
  	 .callback = video_detect_force_video,
  	 .ident = "SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME,
  			  "900X3C/900X3D/900X3E/900X4C/900X4D"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1272633 */
  	 .callback = video_detect_force_video,
  	 .ident = "Dell XPS14 L421X",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
  	 .callback = video_detect_force_video,
  	 .ident = "Dell XPS15 L521X",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
  		},
  	},
  	{
  	 /* https://bugzilla.kernel.org/show_bug.cgi?id=108971 */
  	 .callback = video_detect_force_video,
  	 .ident = "SAMSUNG 530U4E/540U4E",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "530U4E/540U4E"),
  		},
  	},
  
  	/* Non win8 machines which need native backlight nevertheless */
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1201530 */
  	 .callback = video_detect_force_native,
  	 .ident = "Lenovo Ideapad S405",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_BOARD_NAME, "Lenovo IdeaPad S405"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
  	 .callback = video_detect_force_native,
  	 .ident = "Lenovo Ideapad Z570",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1217249 */
  	 .callback = video_detect_force_native,
  	 .ident = "Apple MacBook Pro 12,1",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro12,1"),
  		},
  	},
  	{
  	 .callback = video_detect_force_native,
  	 .ident = "Dell Vostro V131",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
  		},
  	},
  	{
  	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1123661 */
  	 .callback = video_detect_force_native,
  	 .ident = "Dell XPS 17 L702X",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Dell System XPS L702X"),
  		},
  	},
  	{
  	 .callback = video_detect_force_native,
  	 .ident = "Dell Precision 7510",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Precision 7510"),
  		},
  	},
  	{ },
  };
  
  /* This uses a workqueue to avoid various locking ordering issues */
  static void acpi_video_backlight_notify_work(struct work_struct *work)
  {
  	if (acpi_video_get_backlight_type() != acpi_backlight_video)
  		acpi_video_unregister_backlight();
  }
  
  static int acpi_video_backlight_notify(struct notifier_block *nb,
  				       unsigned long val, void *bd)
  {
  	struct backlight_device *backlight = bd;
  
  	/* A raw bl registering may change video -> native */
  	if (backlight->props.type == BACKLIGHT_RAW &&
  	    val == BACKLIGHT_REGISTERED)
  		schedule_work(&backlight_notify_work);
  
  	return NOTIFY_OK;
  }
  
  /*
   * Determine which type of backlight interface to use on this system,
   * First check cmdline, then dmi quirks, then do autodetect.
   *
   * The autodetect order is:
   * 1) Is the acpi-video backlight interface supported ->
   *  no, use a vendor interface
   * 2) Is this a win8 "ready" BIOS and do we have a native interface ->
   *  yes, use a native interface
   * 3) Else use the acpi-video interface
   *
   * Arguably the native on win8 check should be done first, but that would
   * be a behavior change, which may causes issues.
   */
  enum acpi_backlight_type acpi_video_get_backlight_type(void)
  {
  	static DEFINE_MUTEX(init_mutex);
  	static bool init_done;
  	static long video_caps;
  
  	/* Parse cmdline, dmi and acpi only once */
  	mutex_lock(&init_mutex);
  	if (!init_done) {
  		acpi_video_parse_cmdline();
  		dmi_check_system(video_detect_dmi_table);
  		acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
  				    ACPI_UINT32_MAX, find_video, NULL,
  				    &video_caps, NULL);
  		INIT_WORK(&backlight_notify_work,
  			  acpi_video_backlight_notify_work);
  		backlight_nb.notifier_call = acpi_video_backlight_notify;
  		backlight_nb.priority = 0;
  		if (backlight_register_notifier(&backlight_nb) == 0)
  			backlight_notifier_registered = true;
  		init_done = true;
  	}
  	mutex_unlock(&init_mutex);
  
  	if (acpi_backlight_cmdline != acpi_backlight_undef)
  		return acpi_backlight_cmdline;
  
  	if (acpi_backlight_dmi != acpi_backlight_undef)
  		return acpi_backlight_dmi;
  
  	if (!(video_caps & ACPI_VIDEO_BACKLIGHT))
  		return acpi_backlight_vendor;
  
  	if (acpi_osi_is_win8() && backlight_device_get_by_type(BACKLIGHT_RAW))
  		return acpi_backlight_native;
  
  	return acpi_backlight_video;
  }
  EXPORT_SYMBOL(acpi_video_get_backlight_type);
  
  /*
   * Set the preferred backlight interface type based on DMI info.
   * This function allows DMI blacklists to be implemented by external
   * platform drivers instead of putting a big blacklist in video_detect.c
   */
  void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
  {
  	acpi_backlight_dmi = type;
  	/* Remove acpi-video backlight interface if it is no longer desired */
  	if (acpi_video_get_backlight_type() != acpi_backlight_video)
  		acpi_video_unregister_backlight();
  }
  EXPORT_SYMBOL(acpi_video_set_dmi_backlight_type);
  
  void __exit acpi_video_detect_exit(void)
  {
  	if (backlight_notifier_registered)
  		backlight_unregister_notifier(&backlight_nb);
  }
  