platform/x86: add support for Advantech software defined button

Advantech sw_button is a ACPI event trigger button.

With this driver, we can report KEY_PROG1 on the
Advantech Tabletop Network Appliances products and it has been
tested in FWA1112VC.

Add the software define button support to report EV_REP key_event
(KEY_PROG1) by pressing button that could be get on user
interface and trigger the customized actions.

Signed-off-by: Andrea.Ho <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Hans de Goede <[e-mail]>

MAINTAINERS

···
 F:	Documentation/scsi/advansys.rst
 F:	drivers/scsi/advansys.c
 
+ADVANTECH SWBTN DRIVER
+M:	Andrea Ho <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	drivers/platform/x86/adv_swbutton.c
+
 ADXL34X THREE-AXIS DIGITAL ACCELEROMETER DRIVER (ADXL345/ADXL346)
 M:	Michael Hennerich <[e-mail]>
 S:	Supported

drivers/platform/x86/Kconfig

···
 	  If you choose to compile this driver as a module the module will be
 	  called amd-pmc.
 
+config ADV_SWBUTTON
+	tristate "Advantech ACPI Software Button Driver"
+	depends on ACPI && INPUT
+	help
+	  Say Y here to enable support for Advantech software defined
+	  button feature. More information can be found at
+	  <http://www.advantech.com.tw/products/>
+
+	  To compile this driver as a module, choose M here. The module will
+	  be called adv_swbutton.
+
 config APPLE_GMUX
 	tristate "Apple Gmux Driver"
 	depends on ACPI && PCI

drivers/platform/x86/Makefile

···
 # AMD
 obj-$(CONFIG_AMD_PMC)		+= amd-pmc.o
 
+# Advantech
+obj-$(CONFIG_ADV_SWBUTTON)	+= adv_swbutton.o
+
 # Apple
 obj-$(CONFIG_APPLE_GMUX)	+= apple-gmux.o
 

drivers/platform/x86/adv_swbutton.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  adv_swbutton.c - Software Button Interface Driver.
+ *
+ *  (C) Copyright 2020 Advantech Corporation, Inc
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/acpi.h>
+#include <linux/platform_device.h>
+
+#define ACPI_BUTTON_HID_SWBTN               "AHC0310"
+
+#define ACPI_BUTTON_NOTIFY_SWBTN_RELEASE    0x86
+#define ACPI_BUTTON_NOTIFY_SWBTN_PRESSED    0x85
+
+struct adv_swbutton {
+	struct input_dev *input;
+	char phys[32];
+};
+
+/*-------------------------------------------------------------------------
+ *                               Driver Interface
+ *--------------------------------------------------------------------------
+ */
+static void adv_swbutton_notify(acpi_handle handle, u32 event, void *context)
+{
+	struct platform_device *device = context;
+	struct adv_swbutton *button = dev_get_drvdata(&device->dev);
+
+	switch (event) {
+	case ACPI_BUTTON_NOTIFY_SWBTN_RELEASE:
+		input_report_key(button->input, KEY_PROG1, 0);
+		input_sync(button->input);
+		break;
+	case ACPI_BUTTON_NOTIFY_SWBTN_PRESSED:
+		input_report_key(button->input, KEY_PROG1, 1);
+		input_sync(button->input);
+		break;
+	default:
+		dev_dbg(&device->dev, "Unsupported event [0x%x]\n", event);
+	}
+}
+
+static int adv_swbutton_probe(struct platform_device *device)
+{
+	struct adv_swbutton *button;
+	struct input_dev *input;
+	acpi_handle handle = ACPI_HANDLE(&device->dev);
+	acpi_status status;
+	int error;
+
+	button = devm_kzalloc(&device->dev, sizeof(*button), GFP_KERNEL);
+	if (!button)
+		return -ENOMEM;
+
+	dev_set_drvdata(&device->dev, button);
+
+	input = devm_input_allocate_device(&device->dev);
+	if (!input)
+		return -ENOMEM;
+
+	button->input = input;
+	snprintf(button->phys, sizeof(button->phys), "%s/button/input0", ACPI_BUTTON_HID_SWBTN);
+
+	input->name = "Advantech Software Button";
+	input->phys = button->phys;
+	input->id.bustype = BUS_HOST;
+	input->dev.parent = &device->dev;
+	set_bit(EV_REP, input->evbit);
+	input_set_capability(input, EV_KEY, KEY_PROG1);
+
+	error = input_register_device(input);
+	if (error)
+		return error;
+
+	device_init_wakeup(&device->dev, true);
+
+	status = acpi_install_notify_handler(handle,
+					     ACPI_DEVICE_NOTIFY,
+					     adv_swbutton_notify,
+					     device);
+	if (ACPI_FAILURE(status)) {
+		dev_err(&device->dev, "Error installing notify handler\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int adv_swbutton_remove(struct platform_device *device)
+{
+	acpi_handle handle = ACPI_HANDLE(&device->dev);
+
+	acpi_remove_notify_handler(handle, ACPI_DEVICE_NOTIFY,
+				   adv_swbutton_notify);
+
+	return 0;
+}
+
+static const struct acpi_device_id button_device_ids[] = {
+	{ACPI_BUTTON_HID_SWBTN, 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, button_device_ids);
+
+static struct platform_driver adv_swbutton_driver = {
+	.driver = {
+		.name = "adv_swbutton",
+		.acpi_match_table = button_device_ids,
+	},
+	.probe = adv_swbutton_probe,
+	.remove = adv_swbutton_remove,
+};
+module_platform_driver(adv_swbutton_driver);
+
+MODULE_AUTHOR("Andrea Ho");
+MODULE_DESCRIPTION("Advantech ACPI SW Button Driver");
+MODULE_LICENSE("GPL v2");