xref: /openbmc/linux/drivers/input/joystick/zhenhua.c (revision 2d09ac95)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  derived from "twidjoy.c"
4  *
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
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 #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>
37 
38 #define DRIVER_DESC	"RC transmitter with 5-byte Zhen Hua protocol joystick driver"
39 
40 MODULE_DESCRIPTION(DRIVER_DESC);
41 MODULE_LICENSE("GPL");
42 
43 /*
44  * Constants.
45  */
46 
47 #define ZHENHUA_MAX_LENGTH 5
48 
49 /*
50  * Zhen Hua data.
51  */
52 
53 struct zhenhua {
54 	struct input_dev *dev;
55 	int idx;
56 	unsigned char data[ZHENHUA_MAX_LENGTH];
57 	char phys[32];
58 };
59 
60 /*
61  * zhenhua_process_packet() decodes packets the driver receives from the
62  * RC transmitter. It updates the data accordingly.
63  */
64 
zhenhua_process_packet(struct zhenhua * zhenhua)65 static void zhenhua_process_packet(struct zhenhua *zhenhua)
66 {
67 	struct input_dev *dev = zhenhua->dev;
68 	unsigned char *data = zhenhua->data;
69 
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]);
74 
75 	input_sync(dev);
76 }
77 
78 /*
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.
82  */
83 
zhenhua_interrupt(struct serio * serio,unsigned char data,unsigned int flags)84 static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
85 {
86 	struct zhenhua *zhenhua = serio_get_drvdata(serio);
87 
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. */
91 
92 	if (data == 0xef)
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 */
96 
97 	if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
98 		zhenhua->data[zhenhua->idx++] = bitrev8(data);
99 
100 	if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
101 		zhenhua_process_packet(zhenhua);
102 		zhenhua->idx = 0;
103 	}
104 
105 	return IRQ_HANDLED;
106 }
107 
108 /*
109  * zhenhua_disconnect() is the opposite of zhenhua_connect()
110  */
111 
zhenhua_disconnect(struct serio * serio)112 static void zhenhua_disconnect(struct serio *serio)
113 {
114 	struct zhenhua *zhenhua = serio_get_drvdata(serio);
115 
116 	serio_close(serio);
117 	serio_set_drvdata(serio, NULL);
118 	input_unregister_device(zhenhua->dev);
119 	kfree(zhenhua);
120 }
121 
122 /*
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.
126  */
127 
zhenhua_connect(struct serio * serio,struct serio_driver * drv)128 static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
129 {
130 	struct zhenhua *zhenhua;
131 	struct input_dev *input_dev;
132 	int err = -ENOMEM;
133 
134 	zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
135 	input_dev = input_allocate_device();
136 	if (!zhenhua || !input_dev)
137 		goto fail1;
138 
139 	zhenhua->dev = input_dev;
140 	snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
141 
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;
149 
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);
155 
156 	serio_set_drvdata(serio, zhenhua);
157 
158 	err = serio_open(serio, drv);
159 	if (err)
160 		goto fail2;
161 
162 	err = input_register_device(zhenhua->dev);
163 	if (err)
164 		goto fail3;
165 
166 	return 0;
167 
168  fail3:	serio_close(serio);
169  fail2:	serio_set_drvdata(serio, NULL);
170  fail1:	input_free_device(input_dev);
171 	kfree(zhenhua);
172 	return err;
173 }
174 
175 /*
176  * The serio driver structure.
177  */
178 
179 static const struct serio_device_id zhenhua_serio_ids[] = {
180 	{
181 		.type	= SERIO_RS232,
182 		.proto	= SERIO_ZHENHUA,
183 		.id	= SERIO_ANY,
184 		.extra	= SERIO_ANY,
185 	},
186 	{ 0 }
187 };
188 
189 MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
190 
191 static struct serio_driver zhenhua_drv = {
192 	.driver		= {
193 		.name	= "zhenhua",
194 	},
195 	.description	= DRIVER_DESC,
196 	.id_table	= zhenhua_serio_ids,
197 	.interrupt	= zhenhua_interrupt,
198 	.connect	= zhenhua_connect,
199 	.disconnect	= zhenhua_disconnect,
200 };
201 
202 module_serio_driver(zhenhua_drv);
203