1/*
2 * derived from "twidjoy.c"
3 *
4 * Copyright (c) 2008 Martin Kebert
5 * Copyright (c) 2001 Arndt Schoenewald
6 * Copyright (c) 2000-2001 Vojtech Pavlik
7 * Copyright (c) 2000 Mark Fletcher
8 *
9 */
10
11/*
12 * Driver to use 4CH RC transmitter using Zhen Hua 5-byte protocol (Walkera Lama,
13 * EasyCopter etc.) as a joystick under Linux.
14 *
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
20 * 2. byte = X axis
21 * 3. byte = Y axis
22 * 4. byte = RZ axis
23 * 5. byte = Z axis
24 * (and this is repeated)
25 *
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
28 * coder :-(
29 */
30
31/*
32 * This program is free software; you can redistribute it and/or modify
33 * it under the terms of the GNU General Public License as published by
34 * the Free Software Foundation; either version 2 of the License, or
35 * (at your option) any later version.
36 *
37 * This program is distributed in the hope that it will be useful,
38 * but WITHOUT ANY WARRANTY; without even the implied warranty of
39 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
40 * GNU General Public License for more details.
41 *
42 * You should have received a copy of the GNU General Public License
43 * along with this program; if not, write to the Free Software
44 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
45 */
46
47#include <linux/kernel.h>
48#include <linux/module.h>
49#include <linux/slab.h>
50#include <linux/bitrev.h>
51#include <linux/input.h>
52#include <linux/serio.h>
53
54#define DRIVER_DESC "RC transmitter with 5-byte Zhen Hua protocol joystick driver"
55
56MODULE_DESCRIPTION(DRIVER_DESC);
57MODULE_LICENSE("GPL");
58
59/*
60 * Constants.
61 */
62
63#define ZHENHUA_MAX_LENGTH 5
64
65/*
66 * Zhen Hua data.
67 */
68
69struct zhenhua {
70 struct input_dev *dev;
71 int idx;
72 unsigned char data[ZHENHUA_MAX_LENGTH];
73 char phys[32];
74};
75
76/*
77 * zhenhua_process_packet() decodes packets the driver receives from the
78 * RC transmitter. It updates the data accordingly.
79 */
80
81static void zhenhua_process_packet(struct zhenhua *zhenhua)
82{
83 struct input_dev *dev = zhenhua->dev;
84 unsigned char *data = zhenhua->data;
85
86 input_report_abs(dev, ABS_Y, data[1]);
87 input_report_abs(dev, ABS_X, data[2]);
88 input_report_abs(dev, ABS_RZ, data[3]);
89 input_report_abs(dev, ABS_Z, data[4]);
90
91 input_sync(dev);
92}
93
94/*
95 * zhenhua_interrupt() is called by the low level driver when characters
96 * are ready for us. We then buffer them for further processing, or call the
97 * packet processing routine.
98 */
99
100static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
101{
102 struct zhenhua *zhenhua = serio_get_drvdata(serio);
103
104 /* All Zhen Hua packets are 5 bytes. The fact that the first byte
105 * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
106 * can be used to check and regain sync. */
107
108 if (data == 0xef)
109 zhenhua->idx = 0; /* this byte starts a new packet */
110 else if (zhenhua->idx == 0)
111 return IRQ_HANDLED; /* wrong MSB -- ignore this byte */
112
113 if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
114 zhenhua->data[zhenhua->idx++] = bitrev8(data);
115
116 if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
117 zhenhua_process_packet(zhenhua);
118 zhenhua->idx = 0;
119 }
120
121 return IRQ_HANDLED;
122}
123
124/*
125 * zhenhua_disconnect() is the opposite of zhenhua_connect()
126 */
127
128static void zhenhua_disconnect(struct serio *serio)
129{
130 struct zhenhua *zhenhua = serio_get_drvdata(serio);
131
132 serio_close(serio);
133 serio_set_drvdata(serio, NULL);
134 input_unregister_device(zhenhua->dev);
135 kfree(zhenhua);
136}
137
138/*
139 * zhenhua_connect() is the routine that is called when someone adds a
140 * new serio device. It looks for the Twiddler, and if found, registers
141 * it as an input device.
142 */
143
144static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
145{
146 struct zhenhua *zhenhua;
147 struct input_dev *input_dev;
148 int err = -ENOMEM;
149
150 zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
151 input_dev = input_allocate_device();
152 if (!zhenhua || !input_dev)
153 goto fail1;
154
155 zhenhua->dev = input_dev;
156 snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
157
158 input_dev->name = "Zhen Hua 5-byte device";
159 input_dev->phys = zhenhua->phys;
160 input_dev->id.bustype = BUS_RS232;
161 input_dev->id.vendor = SERIO_ZHENHUA;
162 input_dev->id.product = 0x0001;
163 input_dev->id.version = 0x0100;
164 input_dev->dev.parent = &serio->dev;
165
166 input_dev->evbit[0] = BIT(EV_ABS);
167 input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0);
168 input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0);
169 input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0);
170 input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0);
171
172 serio_set_drvdata(serio, zhenhua);
173
174 err = serio_open(serio, drv);
175 if (err)
176 goto fail2;
177
178 err = input_register_device(zhenhua->dev);
179 if (err)
180 goto fail3;
181
182 return 0;
183
184 fail3: serio_close(serio);
185 fail2: serio_set_drvdata(serio, NULL);
186 fail1: input_free_device(input_dev);
187 kfree(zhenhua);
188 return err;
189}
190
191/*
192 * The serio driver structure.
193 */
194
195static const struct serio_device_id zhenhua_serio_ids[] = {
196 {
197 .type = SERIO_RS232,
198 .proto = SERIO_ZHENHUA,
199 .id = SERIO_ANY,
200 .extra = SERIO_ANY,
201 },
202 { 0 }
203};
204
205MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
206
207static struct serio_driver zhenhua_drv = {
208 .driver = {
209 .name = "zhenhua",
210 },
211 .description = DRIVER_DESC,
212 .id_table = zhenhua_serio_ids,
213 .interrupt = zhenhua_interrupt,
214 .connect = zhenhua_connect,
215 .disconnect = zhenhua_disconnect,
216};
217
218module_serio_driver(zhenhua_drv);
219