dell-rbtn: Dell Airplane Mode Switch driver

This is an ACPI driver for Dell laptops which receive HW slider radio
switch or hotkey toggle wifi button events. It exports rfkill device
dell-rbtn (which provide correct hard rfkill state) or hotkey input device.

Alex Hung is author of original hotkey input device code.
Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Cc: Alex Hung <alex.hung@canonical.com>
[fengguang.wu@intel.com: rbtn_ops can be static]
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
[dvhart@linux.intel.com: Correct multi-line comment formatting]
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

MAINTAINERS

@@ -3071,6 +3071,11 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	drivers/platform/x86/dell-laptop.c
 
+DELL LAPTOP RBTN DRIVER
+M:	Pali Rohár <pali.rohar@gmail.com>
+S:	Maintained
+F:	drivers/platform/x86/dell-rbtn.*
+
 DELL LAPTOP FREEFALL DRIVER
 M:	Pali Rohár <pali.rohar@gmail.com>
 S:	Maintained

drivers/platform/x86/Kconfig

@@ -138,6 +138,22 @@ config DELL_SMO8800
 	  To compile this driver as a module, choose M here: the module will
 	  be called dell-smo8800.
 
+config DELL_RBTN
+	tristate "Dell Airplane Mode Switch driver"
+	depends on ACPI
+	depends on INPUT
+	depends on RFKILL
+	---help---
+	  Say Y here if you want to support Dell Airplane Mode Switch ACPI
+	  device on Dell laptops. Sometimes it has names: DELLABCE or DELRBTN.
+	  This driver register rfkill device or input hotkey device depending
+	  on hardware type (hw switch slider or keyboard toggle button). For
+	  rfkill devices it receive HW switch events and set correct hard
+	  rfkill state.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called dell-rbtn.
+
 
 config FUJITSU_LAPTOP
 	tristate "Fujitsu Laptop Extras"

drivers/platform/x86/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
 obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
 obj-$(CONFIG_DELL_WMI_AIO)	+= dell-wmi-aio.o
 obj-$(CONFIG_DELL_SMO8800)	+= dell-smo8800.o
+obj-$(CONFIG_DELL_RBTN)		+= dell-rbtn.o
 obj-$(CONFIG_ACER_WMI)		+= acer-wmi.o
 obj-$(CONFIG_ACERHDF)		+= acerhdf.o
 obj-$(CONFIG_HP_ACCEL)		+= hp_accel.o

drivers/platform/x86/dell-rbtn.c

+/*
+    Dell Airplane Mode Switch driver
+    Copyright (C) 2014-2015  Pali Rohár <pali.rohar@gmail.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/module.h>
+#include <linux/acpi.h>
+#include <linux/rfkill.h>
+#include <linux/input.h>
+
+enum rbtn_type {
+	RBTN_UNKNOWN,
+	RBTN_TOGGLE,
+	RBTN_SLIDER,
+};
+
+struct rbtn_data {
+	enum rbtn_type type;
+	struct rfkill *rfkill;
+	struct input_dev *input_dev;
+};
+
+
+/*
+ * acpi functions
+ */
+
+static enum rbtn_type rbtn_check(struct acpi_device *device)
+{
+	unsigned long long output;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(device->handle, "CRBT", NULL, &output);
+	if (ACPI_FAILURE(status))
+		return RBTN_UNKNOWN;
+
+	switch (output) {
+	case 0:
+	case 1:
+		return RBTN_TOGGLE;
+	case 2:
+	case 3:
+		return RBTN_SLIDER;
+	default:
+		return RBTN_UNKNOWN;
+	}
+}
+
+static int rbtn_get(struct acpi_device *device)
+{
+	unsigned long long output;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(device->handle, "GRBT", NULL, &output);
+	if (ACPI_FAILURE(status))
+		return -EINVAL;
+
+	return !output;
+}
+
+static int rbtn_acquire(struct acpi_device *device, bool enable)
+{
+	struct acpi_object_list input;
+	union acpi_object param;
+	acpi_status status;
+
+	param.type = ACPI_TYPE_INTEGER;
+	param.integer.value = enable;
+	input.count = 1;
+	input.pointer = &param;
+
+	status = acpi_evaluate_object(device->handle, "ARBT", &input, NULL);
+	if (ACPI_FAILURE(status))
+		return -EINVAL;
+
+	return 0;
+}
+
+
+/*
+ * rfkill device
+ */
+
+static void rbtn_rfkill_query(struct rfkill *rfkill, void *data)
+{
+	struct acpi_device *device = data;
+	int state;
+
+	state = rbtn_get(device);
+	if (state < 0)
+		return;
+
+	rfkill_set_states(rfkill, state, state);
+}
+
+static int rbtn_rfkill_set_block(void *data, bool blocked)
+{
+	/* NOTE: setting soft rfkill state is not supported */
+	return -EINVAL;
+}
+
+static struct rfkill_ops rbtn_ops = {
+	.query = rbtn_rfkill_query,
+	.set_block = rbtn_rfkill_set_block,
+};
+
+static int rbtn_rfkill_init(struct acpi_device *device)
+{
+	struct rbtn_data *rbtn_data = device->driver_data;
+	int ret;
+
+	if (rbtn_data->rfkill)
+		return 0;
+
+	/*
+	 * NOTE: rbtn controls all radio devices, not only WLAN
+	 *       but rfkill interface does not support "ANY" type
+	 *       so "WLAN" type is used
+	 */
+	rbtn_data->rfkill = rfkill_alloc("dell-rbtn", &device->dev,
+					 RFKILL_TYPE_WLAN, &rbtn_ops, device);
+	if (!rbtn_data->rfkill)
+		return -ENOMEM;
+
+	ret = rfkill_register(rbtn_data->rfkill);
+	if (ret) {
+		rfkill_destroy(rbtn_data->rfkill);
+		rbtn_data->rfkill = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+static void rbtn_rfkill_exit(struct acpi_device *device)
+{
+	struct rbtn_data *rbtn_data = device->driver_data;
+
+	if (!rbtn_data->rfkill)
+		return;
+
+	rfkill_unregister(rbtn_data->rfkill);
+	rfkill_destroy(rbtn_data->rfkill);
+	rbtn_data->rfkill = NULL;
+}
+
+static void rbtn_rfkill_event(struct acpi_device *device)
+{
+	struct rbtn_data *rbtn_data = device->driver_data;
+
+	if (rbtn_data->rfkill)
+		rbtn_rfkill_query(rbtn_data->rfkill, device);
+}
+
+
+/*
+ * input device
+ */
+
+static int rbtn_input_init(struct rbtn_data *rbtn_data)
+{
+	int ret;
+
+	rbtn_data->input_dev = input_allocate_device();
+	if (!rbtn_data->input_dev)
+		return -ENOMEM;
+
+	rbtn_data->input_dev->name = "DELL Wireless hotkeys";
+	rbtn_data->input_dev->phys = "dellabce/input0";
+	rbtn_data->input_dev->id.bustype = BUS_HOST;
+	rbtn_data->input_dev->evbit[0] = BIT(EV_KEY);
+	set_bit(KEY_RFKILL, rbtn_data->input_dev->keybit);
+
+	ret = input_register_device(rbtn_data->input_dev);
+	if (ret) {
+		input_free_device(rbtn_data->input_dev);
+		rbtn_data->input_dev = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+static void rbtn_input_exit(struct rbtn_data *rbtn_data)
+{
+	input_unregister_device(rbtn_data->input_dev);
+	rbtn_data->input_dev = NULL;
+}
+
+static void rbtn_input_event(struct rbtn_data *rbtn_data)
+{
+	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 1);
+	input_sync(rbtn_data->input_dev);
+	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 0);
+	input_sync(rbtn_data->input_dev);
+}
+
+
+/*
+ * acpi driver
+ */
+
+static int rbtn_add(struct acpi_device *device);
+static int rbtn_remove(struct acpi_device *device);
+static void rbtn_notify(struct acpi_device *device, u32 event);
+
+static const struct acpi_device_id rbtn_ids[] = {
+	{ "DELRBTN", 0 },
+	{ "DELLABCE", 0 },
+	{ "", 0 },
+};
+
+static struct acpi_driver rbtn_driver = {
+	.name = "dell-rbtn",
+	.ids = rbtn_ids,
+	.ops = {
+		.add = rbtn_add,
+		.remove = rbtn_remove,
+		.notify = rbtn_notify,
+	},
+	.owner = THIS_MODULE,
+};
+
+
+/*
+ * acpi driver functions
+ */
+
+static int rbtn_add(struct acpi_device *device)
+{
+	struct rbtn_data *rbtn_data;
+	enum rbtn_type type;
+	int ret = 0;
+
+	type = rbtn_check(device);
+	if (type == RBTN_UNKNOWN) {
+		dev_info(&device->dev, "Unknown device type\n");
+		return -EINVAL;
+	}
+
+	ret = rbtn_acquire(device, true);
+	if (ret < 0) {
+		dev_err(&device->dev, "Cannot enable device\n");
+		return ret;
+	}
+
+	rbtn_data = devm_kzalloc(&device->dev, sizeof(*rbtn_data), GFP_KERNEL);
+	if (!rbtn_data)
+		return -ENOMEM;
+
+	rbtn_data->type = type;
+	device->driver_data = rbtn_data;
+
+	switch (rbtn_data->type) {
+	case RBTN_TOGGLE:
+		ret = rbtn_input_init(rbtn_data);
+		break;
+	case RBTN_SLIDER:
+		ret = rbtn_rfkill_init(device);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+
+}
+
+static int rbtn_remove(struct acpi_device *device)
+{
+	struct rbtn_data *rbtn_data = device->driver_data;
+
+	switch (rbtn_data->type) {
+	case RBTN_TOGGLE:
+		rbtn_input_exit(rbtn_data);
+		break;
+	case RBTN_SLIDER:
+		rbtn_rfkill_exit(device);
+		break;
+	default:
+		break;
+	}
+
+	rbtn_acquire(device, false);
+	device->driver_data = NULL;
+
+	return 0;
+}
+
+static void rbtn_notify(struct acpi_device *device, u32 event)
+{
+	struct rbtn_data *rbtn_data = device->driver_data;
+
+	if (event != 0x80) {
+		dev_info(&device->dev, "Received unknown event (0x%x)\n",
+			 event);
+		return;
+	}
+
+	switch (rbtn_data->type) {
+	case RBTN_TOGGLE:
+		rbtn_input_event(rbtn_data);
+		break;
+	case RBTN_SLIDER:
+		rbtn_rfkill_event(device);
+		break;
+	default:
+		break;
+	}
+}
+
+
+/*
+ * module functions
+ */
+
+module_acpi_driver(rbtn_driver);
+
+MODULE_DEVICE_TABLE(acpi, rbtn_ids);
+MODULE_DESCRIPTION("Dell Airplane Mode Switch driver");
+MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
+MODULE_LICENSE("GPL");