text: // SPDX-License-Identifier: GPL-2.0+
  /*
   *  Intel Virtual Button driver for Windows 8.1+
   *
   *  Copyright (C) 2016 AceLan Kao <acelan.kao@canonical.com>
   *  Copyright (C) 2016 Alex Hung <alex.hung@canonical.com>
   */
  
  #include <linux/acpi.h>
  #include <linux/dmi.h>
  #include <linux/input.h>
  #include <linux/input/sparse-keymap.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/suspend.h>
  
  /* When NOT in tablet mode, VGBS returns with the flag 0x40 */
  #define TABLET_MODE_FLAG 0x40
  #define DOCK_MODE_FLAG   0x80
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("AceLan Kao");
  
  static const struct acpi_device_id intel_vbtn_ids[] = {
  	{"INT33D6", 0},
  	{"", 0},
  };
  
  /* In theory, these are HID usages. */
  static const struct key_entry intel_vbtn_keymap[] = {
  	{ KE_KEY, 0xC0, { KEY_POWER } },	/* power key press */
  	{ KE_IGNORE, 0xC1, { KEY_POWER } },	/* power key release */
  	{ KE_KEY, 0xC2, { KEY_LEFTMETA } },		/* 'Windows' key press */
  	{ KE_KEY, 0xC3, { KEY_LEFTMETA } },		/* 'Windows' key release */
  	{ KE_KEY, 0xC4, { KEY_VOLUMEUP } },		/* volume-up key press */
  	{ KE_IGNORE, 0xC5, { KEY_VOLUMEUP } },		/* volume-up key release */
  	{ KE_KEY, 0xC6, { KEY_VOLUMEDOWN } },		/* volume-down key press */
  	{ KE_IGNORE, 0xC7, { KEY_VOLUMEDOWN } },	/* volume-down key release */
  	{ KE_KEY,    0xC8, { KEY_ROTATE_LOCK_TOGGLE } },	/* rotate-lock key press */
  	{ KE_KEY,    0xC9, { KEY_ROTATE_LOCK_TOGGLE } },	/* rotate-lock key release */
  	{ KE_SW,     0xCA, { .sw = { SW_DOCK, 1 } } },		/* Docked */
  	{ KE_SW,     0xCB, { .sw = { SW_DOCK, 0 } } },		/* Undocked */
  	{ KE_SW,     0xCC, { .sw = { SW_TABLET_MODE, 1 } } },	/* Tablet */
  	{ KE_SW,     0xCD, { .sw = { SW_TABLET_MODE, 0 } } },	/* Laptop */
  	{ KE_END },
  };
  
  struct intel_vbtn_priv {
  	struct input_dev *input_dev;
  	bool wakeup_mode;
  };
  
  static int intel_vbtn_input_setup(struct platform_device *device)
  {
  	struct intel_vbtn_priv *priv = dev_get_drvdata(&device->dev);
  	int ret;
  
  	priv->input_dev = devm_input_allocate_device(&device->dev);
  	if (!priv->input_dev)
  		return -ENOMEM;
  
  	ret = sparse_keymap_setup(priv->input_dev, intel_vbtn_keymap, NULL);
  	if (ret)
  		return ret;
  
  	priv->input_dev->dev.parent = &device->dev;
  	priv->input_dev->name = "Intel Virtual Button driver";
  	priv->input_dev->id.bustype = BUS_HOST;
  
  	return input_register_device(priv->input_dev);
  }
  
  static void notify_handler(acpi_handle handle, u32 event, void *context)
  {
  	struct platform_device *device = context;
  	struct intel_vbtn_priv *priv = dev_get_drvdata(&device->dev);
  	unsigned int val = !(event & 1); /* Even=press, Odd=release */
  	const struct key_entry *ke, *ke_rel;
  	bool autorelease;
  
  	if (priv->wakeup_mode) {
  		ke = sparse_keymap_entry_from_scancode(priv->input_dev, event);
  		if (ke) {
  			pm_wakeup_hard_event(&device->dev);
  
  			/*
  			 * Switch events like tablet mode will wake the device
  			 * and report the new switch position to the input
  			 * subsystem.
  			 */
  			if (ke->type == KE_SW)
  				sparse_keymap_report_event(priv->input_dev,
  							   event,
  							   val,
  							   0);
  			return;
  		}
  		goto out_unknown;
  	}
  
  	/*
  	 * Even press events are autorelease if there is no corresponding odd
  	 * release event, or if the odd event is KE_IGNORE.
  	 */
  	ke_rel = sparse_keymap_entry_from_scancode(priv->input_dev, event | 1);
  	autorelease = val && (!ke_rel || ke_rel->type == KE_IGNORE);
  
  	if (sparse_keymap_report_event(priv->input_dev, event, val, autorelease))
  		return;
  
  out_unknown:
  	dev_dbg(&device->dev, "unknown event index 0x%x\n", event);
  }
  
  static void detect_tablet_mode(struct platform_device *device)
  {
  	const char *chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
  	struct intel_vbtn_priv *priv = dev_get_drvdata(&device->dev);
  	acpi_handle handle = ACPI_HANDLE(&device->dev);
  	struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };
  	union acpi_object *obj;
  	acpi_status status;
  	int m;
  
  	if (!(chassis_type && strcmp(chassis_type, "31") == 0))
  		goto out;
  
  	status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
  	if (ACPI_FAILURE(status))
  		goto out;
  
  	obj = vgbs_output.pointer;
  	if (!(obj && obj->type == ACPI_TYPE_INTEGER))
  		goto out;
  
  	m = !(obj->integer.value & TABLET_MODE_FLAG);
  	input_report_switch(priv->input_dev, SW_TABLET_MODE, m);
  	m = (obj->integer.value & DOCK_MODE_FLAG) ? 1 : 0;
  	input_report_switch(priv->input_dev, SW_DOCK, m);
  out:
  	kfree(vgbs_output.pointer);
  }
  
  static int intel_vbtn_probe(struct platform_device *device)
  {
  	acpi_handle handle = ACPI_HANDLE(&device->dev);
  	struct intel_vbtn_priv *priv;
  	acpi_status status;
  	int err;
  
  	status = acpi_evaluate_object(handle, "VBDL", NULL, NULL);
  	if (ACPI_FAILURE(status)) {
  		dev_warn(&device->dev, "failed to read Intel Virtual Button driver\n");
  		return -ENODEV;
  	}
  
  	priv = devm_kzalloc(&device->dev, sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  	dev_set_drvdata(&device->dev, priv);
  
  	err = intel_vbtn_input_setup(device);
  	if (err) {
  		pr_err("Failed to setup Intel Virtual Button\n");
  		return err;
  	}
  
  	detect_tablet_mode(device);
  
  	status = acpi_install_notify_handler(handle,
  					     ACPI_DEVICE_NOTIFY,
  					     notify_handler,
  					     device);
  	if (ACPI_FAILURE(status))
  		return -EBUSY;
  
  	device_init_wakeup(&device->dev, true);
  	/*
  	 * In order for system wakeup to work, the EC GPE has to be marked as
  	 * a wakeup one, so do that here (this setting will persist, but it has
  	 * no effect until the wakeup mask is set for the EC GPE).
  	 */
  	acpi_ec_mark_gpe_for_wake();
  	return 0;
  }
  
  static int intel_vbtn_remove(struct platform_device *device)
  {
  	acpi_handle handle = ACPI_HANDLE(&device->dev);
  
  	device_init_wakeup(&device->dev, false);
  	acpi_remove_notify_handler(handle, ACPI_DEVICE_NOTIFY, notify_handler);
  
  	/*
  	 * Even if we failed to shut off the event stream, we can still
  	 * safely detach from the device.
  	 */
  	return 0;
  }
  
  static int intel_vbtn_pm_prepare(struct device *dev)
  {
  	if (device_may_wakeup(dev)) {
  		struct intel_vbtn_priv *priv = dev_get_drvdata(dev);
  
  		priv->wakeup_mode = true;
  	}
  	return 0;
  }
  
  static void intel_vbtn_pm_complete(struct device *dev)
  {
  	struct intel_vbtn_priv *priv = dev_get_drvdata(dev);
  
  	priv->wakeup_mode = false;
  }
  
  static int intel_vbtn_pm_resume(struct device *dev)
  {
  	intel_vbtn_pm_complete(dev);
  	return 0;
  }
  
  static const struct dev_pm_ops intel_vbtn_pm_ops = {
  	.prepare = intel_vbtn_pm_prepare,
  	.complete = intel_vbtn_pm_complete,
  	.resume = intel_vbtn_pm_resume,
  	.restore = intel_vbtn_pm_resume,
  	.thaw = intel_vbtn_pm_resume,
  };
  
  static struct platform_driver intel_vbtn_pl_driver = {
  	.driver = {
  		.name = "intel-vbtn",
  		.acpi_match_table = intel_vbtn_ids,
  		.pm = &intel_vbtn_pm_ops,
  	},
  	.probe = intel_vbtn_probe,
  	.remove = intel_vbtn_remove,
  };
  MODULE_DEVICE_TABLE(acpi, intel_vbtn_ids);
  
  static acpi_status __init
  check_acpi_dev(acpi_handle handle, u32 lvl, void *context, void **rv)
  {
  	const struct acpi_device_id *ids = context;
  	struct acpi_device *dev;
  
  	if (acpi_bus_get_device(handle, &dev) != 0)
  		return AE_OK;
  
  	if (acpi_match_device_ids(dev, ids) == 0)
  		if (acpi_create_platform_device(dev, NULL))
  			dev_info(&dev->dev,
  				 "intel-vbtn: created platform device\n");
  
  	return AE_OK;
  }
  
  static int __init intel_vbtn_init(void)
  {
  	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
  			    ACPI_UINT32_MAX, check_acpi_dev, NULL,
  			    (void *)intel_vbtn_ids, NULL);
  
  	return platform_driver_register(&intel_vbtn_pl_driver);
  }
  module_init(intel_vbtn_init);
  
  static void __exit intel_vbtn_exit(void)
  {
  	platform_driver_unregister(&intel_vbtn_pl_driver);
  }
  module_exit(intel_vbtn_exit);
  