linux/drivers/input/joystick/zhenhua.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  derived from "twidjoy.c"
 *
 *  Copyright (c) 2008 Martin Kebert
 *  Copyright (c) 2001 Arndt Schoenewald
 *  Copyright (c) 2000-2001 Vojtech Pavlik
 *  Copyright (c) 2000 Mark Fletcher
 */

/*
 * Driver to use 4CH RC transmitter using Zhen Hua 5-byte protocol (Walkera Lama,
 * EasyCopter etc.) as a joystick under Linux.
 *
 * RC transmitters using Zhen Hua 5-byte protocol are cheap four channels
 * transmitters for control a RC planes or RC helicopters with possibility to
 * connect on a serial port.
 * Data coming from transmitter is in this order:
 * 1. byte = synchronisation byte
 * 2. byte = X axis
 * 3. byte = Y axis
 * 4. byte = RZ axis
 * 5. byte = Z axis
 * (and this is repeated)
 *
 * For questions or feedback regarding this driver module please contact:
 * Martin Kebert <[email protected]> - but I am not a C-programmer nor kernel
 * coder :-(
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/bitrev.h>
#include <linux/input.h>
#include <linux/serio.h>

#define DRIVER_DESC …

MODULE_DESCRIPTION(…);
MODULE_LICENSE(…) …;

/*
 * Constants.
 */

#define ZHENHUA_MAX_LENGTH …

/*
 * Zhen Hua data.
 */

struct zhenhua { … };

/*
 * zhenhua_process_packet() decodes packets the driver receives from the
 * RC transmitter. It updates the data accordingly.
 */

static void zhenhua_process_packet(struct zhenhua *zhenhua)
{ … }

/*
 * zhenhua_interrupt() is called by the low level driver when characters
 * are ready for us. We then buffer them for further processing, or call the
 * packet processing routine.
 */

static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
{ … }

/*
 * zhenhua_disconnect() is the opposite of zhenhua_connect()
 */

static void zhenhua_disconnect(struct serio *serio)
{ … }

/*
 * zhenhua_connect() is the routine that is called when someone adds a
 * new serio device. It looks for the Twiddler, and if found, registers
 * it as an input device.
 */

static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
{ … }

/*
 * The serio driver structure.
 */

static const struct serio_device_id zhenhua_serio_ids[] = …;

MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);

static struct serio_driver zhenhua_drv = …;

module_serio_driver(…) …;