1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * derived from "twidjoy.c"
5 * Copyright (c) 2008 Martin Kebert
6 * Copyright (c) 2001 Arndt Schoenewald
7 * Copyright (c) 2000-2001 Vojtech Pavlik
8 * Copyright (c) 2000 Mark Fletcher
12 * Driver to use 4CH RC transmitter using Zhen Hua 5-byte protocol (Walkera Lama,
13 * EasyCopter etc.) as a joystick under Linux.
15 * RC transmitters using Zhen Hua 5-byte protocol are cheap four channels
16 * transmitters for control a RC planes or RC helicopters with possibility to
17 * connect on a serial port.
18 * Data coming from transmitter is in this order:
19 * 1. byte = synchronisation byte
24 * (and this is repeated)
26 * For questions or feedback regarding this driver module please contact:
27 * Martin Kebert <gkmarty@gmail.com> - but I am not a C-programmer nor kernel
31 #include <linux/kernel.h>
32 #include <linux/module.h>
33 #include <linux/slab.h>
34 #include <linux/bitrev.h>
35 #include <linux/input.h>
36 #include <linux/serio.h>
38 #define DRIVER_DESC "RC transmitter with 5-byte Zhen Hua protocol joystick driver"
40 MODULE_DESCRIPTION(DRIVER_DESC
);
41 MODULE_LICENSE("GPL");
47 #define ZHENHUA_MAX_LENGTH 5
54 struct input_dev
*dev
;
56 unsigned char data
[ZHENHUA_MAX_LENGTH
];
61 * zhenhua_process_packet() decodes packets the driver receives from the
62 * RC transmitter. It updates the data accordingly.
65 static void zhenhua_process_packet(struct zhenhua
*zhenhua
)
67 struct input_dev
*dev
= zhenhua
->dev
;
68 unsigned char *data
= zhenhua
->data
;
70 input_report_abs(dev
, ABS_Y
, data
[1]);
71 input_report_abs(dev
, ABS_X
, data
[2]);
72 input_report_abs(dev
, ABS_RZ
, data
[3]);
73 input_report_abs(dev
, ABS_Z
, data
[4]);
79 * zhenhua_interrupt() is called by the low level driver when characters
80 * are ready for us. We then buffer them for further processing, or call the
81 * packet processing routine.
84 static irqreturn_t
zhenhua_interrupt(struct serio
*serio
, unsigned char data
, unsigned int flags
)
86 struct zhenhua
*zhenhua
= serio_get_drvdata(serio
);
88 /* All Zhen Hua packets are 5 bytes. The fact that the first byte
89 * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
90 * can be used to check and regain sync. */
93 zhenhua
->idx
= 0; /* this byte starts a new packet */
94 else if (zhenhua
->idx
== 0)
95 return IRQ_HANDLED
; /* wrong MSB -- ignore this byte */
97 if (zhenhua
->idx
< ZHENHUA_MAX_LENGTH
)
98 zhenhua
->data
[zhenhua
->idx
++] = bitrev8(data
);
100 if (zhenhua
->idx
== ZHENHUA_MAX_LENGTH
) {
101 zhenhua_process_packet(zhenhua
);
109 * zhenhua_disconnect() is the opposite of zhenhua_connect()
112 static void zhenhua_disconnect(struct serio
*serio
)
114 struct zhenhua
*zhenhua
= serio_get_drvdata(serio
);
117 serio_set_drvdata(serio
, NULL
);
118 input_unregister_device(zhenhua
->dev
);
123 * zhenhua_connect() is the routine that is called when someone adds a
124 * new serio device. It looks for the Twiddler, and if found, registers
125 * it as an input device.
128 static int zhenhua_connect(struct serio
*serio
, struct serio_driver
*drv
)
130 struct zhenhua
*zhenhua
;
131 struct input_dev
*input_dev
;
134 zhenhua
= kzalloc(sizeof(*zhenhua
), GFP_KERNEL
);
135 input_dev
= input_allocate_device();
136 if (!zhenhua
|| !input_dev
)
139 zhenhua
->dev
= input_dev
;
140 snprintf(zhenhua
->phys
, sizeof(zhenhua
->phys
), "%s/input0", serio
->phys
);
142 input_dev
->name
= "Zhen Hua 5-byte device";
143 input_dev
->phys
= zhenhua
->phys
;
144 input_dev
->id
.bustype
= BUS_RS232
;
145 input_dev
->id
.vendor
= SERIO_ZHENHUA
;
146 input_dev
->id
.product
= 0x0001;
147 input_dev
->id
.version
= 0x0100;
148 input_dev
->dev
.parent
= &serio
->dev
;
150 input_dev
->evbit
[0] = BIT(EV_ABS
);
151 input_set_abs_params(input_dev
, ABS_X
, 50, 200, 0, 0);
152 input_set_abs_params(input_dev
, ABS_Y
, 50, 200, 0, 0);
153 input_set_abs_params(input_dev
, ABS_Z
, 50, 200, 0, 0);
154 input_set_abs_params(input_dev
, ABS_RZ
, 50, 200, 0, 0);
156 serio_set_drvdata(serio
, zhenhua
);
158 err
= serio_open(serio
, drv
);
162 err
= input_register_device(zhenhua
->dev
);
168 fail3
: serio_close(serio
);
169 fail2
: serio_set_drvdata(serio
, NULL
);
170 fail1
: input_free_device(input_dev
);
176 * The serio driver structure.
179 static const struct serio_device_id zhenhua_serio_ids
[] = {
182 .proto
= SERIO_ZHENHUA
,
189 MODULE_DEVICE_TABLE(serio
, zhenhua_serio_ids
);
191 static struct serio_driver zhenhua_drv
= {
195 .description
= DRIVER_DESC
,
196 .id_table
= zhenhua_serio_ids
,
197 .interrupt
= zhenhua_interrupt
,
198 .connect
= zhenhua_connect
,
199 .disconnect
= zhenhua_disconnect
,
202 module_serio_driver(zhenhua_drv
);