intel-vbtn: new driver for Intel Virtual Button

BugLink: https://bugs.launchpad.net/bugs/1609204

This driver supports power button event in Intel Virtual Button currently.
New Dell XPS 13 requires this driver for the power button.

This driver is copied/modified from intel-hid.c
Most credit goes to the author of intel-hid.c,
Alex Hung <alex.hung@canonical.com>
Signed-off-by: AceLan Kao <acelan.kao@canonical.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
(cherry picked from commit 332e0812)
Signed-off-by: AceLan Kao <acelan.kao@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

MAINTAINERS

@@ -5529,6 +5529,12 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	drivers/platform/x86/intel-hid.c
 
+INTEL VIRTUAL BUTTON DRIVER
+M:	AceLan Kao <acelan.kao@canonical.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	drivers/platform/x86/intel-vbtn.c
+
 INTEL IDLE DRIVER
 M:	Len Brown <lenb@kernel.org>
 L:	linux-pm@vger.kernel.org

drivers/platform/x86/Kconfig

@@ -743,6 +743,18 @@ config INTEL_HID_EVENT
 	  To compile this driver as a module, choose M here: the module will
 	  be called intel_hid.
 
+config INTEL_VBTN
+	tristate "INTEL VIRTUAL BUTTON"
+	depends on ACPI
+	depends on INPUT
+	select INPUT_SPARSEKMAP
+	help
+	  This driver provides support for the Intel Virtual Button interface.
+	  Some laptops require this driver for power button support.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called intel_vbtn.
+
 config INTEL_SCU_IPC
 	bool "Intel SCU IPC Support"
 	depends on X86_INTEL_MID

drivers/platform/x86/Makefile

@@ -42,6 +42,7 @@ obj-$(CONFIG_TOSHIBA_BT_RFKILL)	+= toshiba_bluetooth.o
 obj-$(CONFIG_TOSHIBA_HAPS)	+= toshiba_haps.o
 obj-$(CONFIG_TOSHIBA_WMI)	+= toshiba-wmi.o
 obj-$(CONFIG_INTEL_HID_EVENT)	+= intel-hid.o
+obj-$(CONFIG_INTEL_VBTN)	+= intel-vbtn.o
 obj-$(CONFIG_INTEL_SCU_IPC)	+= intel_scu_ipc.o
 obj-$(CONFIG_INTEL_SCU_IPC_UTIL) += intel_scu_ipcutil.o
 obj-$(CONFIG_INTEL_MFLD_THERMAL) += intel_mid_thermal.o

drivers/platform/x86/intel-vbtn.c

+/*
+ *  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>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/platform_device.h>
+#include <linux/input/sparse-keymap.h>
+#include <linux/acpi.h>
+#include <acpi/acpi_bus.h>
+
+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_IGNORE, 0xC0, { KEY_POWER } },	/* power key press */
+	{ KE_KEY, 0xC1, { KEY_POWER } },	/* power key release */
+	{ KE_END },
+};
+
+struct intel_vbtn_priv {
+	struct input_dev *input_dev;
+};
+
+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 = input_allocate_device();
+	if (!priv->input_dev)
+		return -ENOMEM;
+
+	ret = sparse_keymap_setup(priv->input_dev, intel_vbtn_keymap, NULL);
+	if (ret)
+		goto err_free_device;
+
+	priv->input_dev->dev.parent = &device->dev;
+	priv->input_dev->name = "Intel Virtual Button driver";
+	priv->input_dev->id.bustype = BUS_HOST;
+
+	ret = input_register_device(priv->input_dev);
+	if (ret)
+		goto err_free_device;
+
+	return 0;
+
+err_free_device:
+	input_free_device(priv->input_dev);
+	return ret;
+}
+
+static void intel_vbtn_input_destroy(struct platform_device *device)
+{
+	struct intel_vbtn_priv *priv = dev_get_drvdata(&device->dev);
+
+	input_unregister_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);
+
+	if (!sparse_keymap_report_event(priv->input_dev, event, 1, true))
+		dev_info(&device->dev, "unknown event index 0x%x\n",
+			 event);
+}
+
+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_SUCCESS(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;
+	}
+
+	status = acpi_install_notify_handler(handle,
+					     ACPI_DEVICE_NOTIFY,
+					     notify_handler,
+					     device);
+	if (ACPI_FAILURE(status)) {
+		err = -EBUSY;
+		goto err_remove_input;
+	}
+
+	return 0;
+
+err_remove_input:
+	intel_vbtn_input_destroy(device);
+
+	return err;
+}
+
+static int intel_vbtn_remove(struct platform_device *device)
+{
+	acpi_handle handle = ACPI_HANDLE(&device->dev);
+
+	intel_vbtn_input_destroy(device);
+	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 struct platform_driver intel_vbtn_pl_driver = {
+	.driver = {
+		.name = "intel-vbtn",
+		.acpi_match_table = intel_vbtn_ids,
+	},
+	.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))
+			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);