xref: /openbmc/linux/drivers/input/joystick/zhenhua.c (revision c819e2cf)
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/input.h>
51 #include <linux/serio.h>
52 
53 #define DRIVER_DESC	"RC transmitter with 5-byte Zhen Hua protocol joystick driver"
54 
55 MODULE_DESCRIPTION(DRIVER_DESC);
56 MODULE_LICENSE("GPL");
57 
58 /*
59  * Constants.
60  */
61 
62 #define ZHENHUA_MAX_LENGTH 5
63 
64 /*
65  * Zhen Hua data.
66  */
67 
68 struct zhenhua {
69 	struct input_dev *dev;
70 	int idx;
71 	unsigned char data[ZHENHUA_MAX_LENGTH];
72 	char phys[32];
73 };
74 
75 
76 /* bits in all incoming bytes needs to be "reversed" */
77 static int zhenhua_bitreverse(int x)
78 {
79 	x = ((x & 0xaa) >> 1) | ((x & 0x55) << 1);
80 	x = ((x & 0xcc) >> 2) | ((x & 0x33) << 2);
81 	x = ((x & 0xf0) >> 4) | ((x & 0x0f) << 4);
82 	return x;
83 }
84 
85 /*
86  * zhenhua_process_packet() decodes packets the driver receives from the
87  * RC transmitter. It updates the data accordingly.
88  */
89 
90 static void zhenhua_process_packet(struct zhenhua *zhenhua)
91 {
92 	struct input_dev *dev = zhenhua->dev;
93 	unsigned char *data = zhenhua->data;
94 
95 	input_report_abs(dev, ABS_Y, data[1]);
96 	input_report_abs(dev, ABS_X, data[2]);
97 	input_report_abs(dev, ABS_RZ, data[3]);
98 	input_report_abs(dev, ABS_Z, data[4]);
99 
100 	input_sync(dev);
101 }
102 
103 /*
104  * zhenhua_interrupt() is called by the low level driver when characters
105  * are ready for us. We then buffer them for further processing, or call the
106  * packet processing routine.
107  */
108 
109 static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
110 {
111 	struct zhenhua *zhenhua = serio_get_drvdata(serio);
112 
113 	/* All Zhen Hua packets are 5 bytes. The fact that the first byte
114 	 * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
115 	 * can be used to check and regain sync. */
116 
117 	if (data == 0xef)
118 		zhenhua->idx = 0;	/* this byte starts a new packet */
119 	else if (zhenhua->idx == 0)
120 		return IRQ_HANDLED;	/* wrong MSB -- ignore this byte */
121 
122 	if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
123 		zhenhua->data[zhenhua->idx++] = zhenhua_bitreverse(data);
124 
125 	if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
126 		zhenhua_process_packet(zhenhua);
127 		zhenhua->idx = 0;
128 	}
129 
130 	return IRQ_HANDLED;
131 }
132 
133 /*
134  * zhenhua_disconnect() is the opposite of zhenhua_connect()
135  */
136 
137 static void zhenhua_disconnect(struct serio *serio)
138 {
139 	struct zhenhua *zhenhua = serio_get_drvdata(serio);
140 
141 	serio_close(serio);
142 	serio_set_drvdata(serio, NULL);
143 	input_unregister_device(zhenhua->dev);
144 	kfree(zhenhua);
145 }
146 
147 /*
148  * zhenhua_connect() is the routine that is called when someone adds a
149  * new serio device. It looks for the Twiddler, and if found, registers
150  * it as an input device.
151  */
152 
153 static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
154 {
155 	struct zhenhua *zhenhua;
156 	struct input_dev *input_dev;
157 	int err = -ENOMEM;
158 
159 	zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
160 	input_dev = input_allocate_device();
161 	if (!zhenhua || !input_dev)
162 		goto fail1;
163 
164 	zhenhua->dev = input_dev;
165 	snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
166 
167 	input_dev->name = "Zhen Hua 5-byte device";
168 	input_dev->phys = zhenhua->phys;
169 	input_dev->id.bustype = BUS_RS232;
170 	input_dev->id.vendor = SERIO_ZHENHUA;
171 	input_dev->id.product = 0x0001;
172 	input_dev->id.version = 0x0100;
173 	input_dev->dev.parent = &serio->dev;
174 
175 	input_dev->evbit[0] = BIT(EV_ABS);
176 	input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0);
177 	input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0);
178 	input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0);
179 	input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0);
180 
181 	serio_set_drvdata(serio, zhenhua);
182 
183 	err = serio_open(serio, drv);
184 	if (err)
185 		goto fail2;
186 
187 	err = input_register_device(zhenhua->dev);
188 	if (err)
189 		goto fail3;
190 
191 	return 0;
192 
193  fail3:	serio_close(serio);
194  fail2:	serio_set_drvdata(serio, NULL);
195  fail1:	input_free_device(input_dev);
196 	kfree(zhenhua);
197 	return err;
198 }
199 
200 /*
201  * The serio driver structure.
202  */
203 
204 static struct serio_device_id zhenhua_serio_ids[] = {
205 	{
206 		.type	= SERIO_RS232,
207 		.proto	= SERIO_ZHENHUA,
208 		.id	= SERIO_ANY,
209 		.extra	= SERIO_ANY,
210 	},
211 	{ 0 }
212 };
213 
214 MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
215 
216 static struct serio_driver zhenhua_drv = {
217 	.driver		= {
218 		.name	= "zhenhua",
219 	},
220 	.description	= DRIVER_DESC,
221 	.id_table	= zhenhua_serio_ids,
222 	.interrupt	= zhenhua_interrupt,
223 	.connect	= zhenhua_connect,
224 	.disconnect	= zhenhua_disconnect,
225 };
226 
227 module_serio_driver(zhenhua_drv);
228