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// 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 <gkmarty@gmail.com> - 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 "RC transmitter with 5-byte Zhen Hua protocol joystick driver"
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
/*
* Constants.
*/
#define ZHENHUA_MAX_LENGTH 5
/*
* Zhen Hua data.
*/
struct zhenhua {
struct input_dev *dev;
int idx;
unsigned char data[ZHENHUA_MAX_LENGTH];
char phys[32];
};
/*
* 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)
{
struct input_dev *dev = zhenhua->dev;
unsigned char *data = zhenhua->data;
input_report_abs(dev, ABS_Y, data[1]);
input_report_abs(dev, ABS_X, data[2]);
input_report_abs(dev, ABS_RZ, data[3]);
input_report_abs(dev, ABS_Z, data[4]);
input_sync(dev);
}
/*
* 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)
{
struct zhenhua *zhenhua = serio_get_drvdata(serio);
/* All Zhen Hua packets are 5 bytes. The fact that the first byte
* is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
* can be used to check and regain sync. */
if (data == 0xef)
zhenhua->idx = 0; /* this byte starts a new packet */
else if (zhenhua->idx == 0)
return IRQ_HANDLED; /* wrong MSB -- ignore this byte */
if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
zhenhua->data[zhenhua->idx++] = bitrev8(data);
if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
zhenhua_process_packet(zhenhua);
zhenhua->idx = 0;
}
return IRQ_HANDLED;
}
/*
* zhenhua_disconnect() is the opposite of zhenhua_connect()
*/
static void zhenhua_disconnect(struct serio *serio)
{
struct zhenhua *zhenhua = serio_get_drvdata(serio);
serio_close(serio);
serio_set_drvdata(serio, NULL);
input_unregister_device(zhenhua->dev);
kfree(zhenhua);
}
/*
* 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)
{
struct zhenhua *zhenhua;
struct input_dev *input_dev;
int err = -ENOMEM;
zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
input_dev = input_allocate_device();
if (!zhenhua || !input_dev)
goto fail1;
zhenhua->dev = input_dev;
snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
input_dev->name = "Zhen Hua 5-byte device";
input_dev->phys = zhenhua->phys;
input_dev->id.bustype = BUS_RS232;
input_dev->id.vendor = SERIO_ZHENHUA;
input_dev->id.product = 0x0001;
input_dev->id.version = 0x0100;
input_dev->dev.parent = &serio->dev;
input_dev->evbit[0] = BIT(EV_ABS);
input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0);
input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0);
input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0);
input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0);
serio_set_drvdata(serio, zhenhua);
err = serio_open(serio, drv);
if (err)
goto fail2;
err = input_register_device(zhenhua->dev);
if (err)
goto fail3;
return 0;
fail3: serio_close(serio);
fail2: serio_set_drvdata(serio, NULL);
fail1: input_free_device(input_dev);
kfree(zhenhua);
return err;
}
/*
* The serio driver structure.
*/
static const struct serio_device_id zhenhua_serio_ids[] = {
{
.type = SERIO_RS232,
.proto = SERIO_ZHENHUA,
.id = SERIO_ANY,
.extra = SERIO_ANY,
},
{ 0 }
};
MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
static struct serio_driver zhenhua_drv = {
.driver = {
.name = "zhenhua",
},
.description = DRIVER_DESC,
.id_table = zhenhua_serio_ids,
.interrupt = zhenhua_interrupt,
.connect = zhenhua_connect,
.disconnect = zhenhua_disconnect,
};
module_serio_driver(zhenhua_drv);
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