HID: Add driver for Retrode2 joypad adapter

This driver does 2 things:

- Apply the MULTI_INPUT quirk to create separate joypad device nodes
for each one of the 4 connectors.
- Rename the input devices so that their names are different, and allow
users to recognise which device corresponds to which physical port,
including the SNES (Mario Paint) Mouse.

Signed-off-by: Bastien Nocera <[e-mail]>
Reviewed-by: Benjamin Tissoires <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/Kconfig

···
 	Support for Primax devices that are not fully compliant with the
 	HID standard.
 
+config HID_RETRODE
+	tristate "Retrode"
+	depends on USB_HID
+	---help---
+	Support for
+
+	  * Retrode 2 cartridge and controller adapter
+
 config HID_ROCCAT
 	tristate "Roccat device support"
 	depends on USB_HID

drivers/hid/Makefile

···
 
 obj-$(CONFIG_HID_PLANTRONICS)	+= hid-plantronics.o
 obj-$(CONFIG_HID_PRIMAX)	+= hid-primax.o
+obj-$(CONFIG_HID_RETRODE)	+= hid-retrode.o
 obj-$(CONFIG_HID_ROCCAT)	+= hid-roccat.o hid-roccat-common.o \
 	hid-roccat-arvo.o hid-roccat-isku.o hid-roccat-kone.o \
 	hid-roccat-koneplus.o hid-roccat-konepure.o hid-roccat-kovaplus.o \

drivers/hid/hid-core.c

···
 #if IS_ENABLED(CONFIG_HID_PRODIKEYS)
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CREATIVELABS, USB_DEVICE_ID_PRODIKEYS_PCMIDI) },
 #endif
+#if IS_ENABLED(CONFIG_HID_RETRODE)
+	{ HID_USB_DEVICE(USB_VENDOR_ID_FUTURE_TECHNOLOGY, USB_DEVICE_ID_RETRODE2) },
+#endif
 #if IS_ENABLED(CONFIG_HID_RMI)
 	{ HID_USB_DEVICE(USB_VENDOR_ID_LENOVO, USB_DEVICE_ID_LENOVO_X1_COVER) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_RAZER, USB_DEVICE_ID_RAZER_BLADE_14) },

drivers/hid/hid-ids.h

···
 #define USB_VENDOR_ID_FUTABA            0x0547
 #define USB_DEVICE_ID_LED_DISPLAY       0x7000
 
+#define USB_VENDOR_ID_FUTURE_TECHNOLOGY	0x0403
+#define USB_DEVICE_ID_RETRODE2		0x97c1
+
 #define USB_VENDOR_ID_ESSENTIAL_REALITY	0x0d7f
 #define USB_DEVICE_ID_ESSENTIAL_REALITY_P5 0x0100
 

drivers/hid/hid-retrode.c

···
+/*
+ *  HID driver for Retrode 2 controller adapter and plug-in extensions
+ *
+ *  Copyright (c) 2017 Bastien Nocera <[e-mail]>
+ */
+
+/*
+ * 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.
+ */
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+#define CONTROLLER_NAME_BASE "Retrode"
+
+static int retrode_input_configured(struct hid_device *hdev,
+					struct hid_input *hi)
+{
+	struct hid_field *field = hi->report->field[0];
+	const char *suffix;
+	int number = 0;
+	char *name;
+
+	switch (field->report->id) {
+	case 0:
+		suffix = "SNES Mouse";
+		break;
+	case 1:
+	case 2:
+		suffix = "SNES / N64";
+		number = field->report->id;
+		break;
+	case 3:
+	case 4:
+		suffix = "Mega Drive";
+		number = field->report->id - 2;
+		break;
+	default:
+		hid_err(hdev, "Got unhandled report id %d\n", field->report->id);
+		suffix = "Unknown";
+	}
+
+	if (number)
+		name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+				"%s %s #%d", CONTROLLER_NAME_BASE,
+				suffix, number);
+	else
+		name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+				"%s %s", CONTROLLER_NAME_BASE, suffix);
+
+	if (!name)
+		return -ENOMEM;
+
+	hi->input->name = name;
+
+	return 0;
+}
+
+static int retrode_probe(struct hid_device *hdev,
+			const struct hid_device_id *id)
+{
+
+	int ret;
+
+	/* Has no effect on the mouse device */
+	hdev->quirks |= HID_QUIRK_MULTI_INPUT;
+
+	ret = hid_parse(hdev);
+	if (ret)
+		return ret;
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct hid_device_id retrode_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_FUTURE_TECHNOLOGY, USB_DEVICE_ID_RETRODE2) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, retrode_devices);
+
+static struct hid_driver retrode_driver = {
+	.name             = "hid-retrode",
+	.id_table         = retrode_devices,
+	.input_configured = retrode_input_configured,
+	.probe            = retrode_probe,
+};
+
+module_hid_driver(retrode_driver);
+
+MODULE_LICENSE("GPL");