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 | |
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, value: data[1]); |
71 | input_report_abs(dev, ABS_X, value: data[2]); |
72 | input_report_abs(dev, ABS_RZ, value: data[3]); |
73 | input_report_abs(dev, ABS_Z, value: 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 | |
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 | |
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(objp: 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 | |
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(size: 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(buf: zhenhua->phys, size: sizeof(zhenhua->phys), fmt: "%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(dev: input_dev, ABS_X, min: 50, max: 200, fuzz: 0, flat: 0); |
152 | input_set_abs_params(dev: input_dev, ABS_Y, min: 50, max: 200, fuzz: 0, flat: 0); |
153 | input_set_abs_params(dev: input_dev, ABS_Z, min: 50, max: 200, fuzz: 0, flat: 0); |
154 | input_set_abs_params(dev: input_dev, ABS_RZ, min: 50, max: 200, fuzz: 0, flat: 0); |
155 | |
156 | serio_set_drvdata(serio, data: 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(dev: input_dev); |
171 | kfree(objp: 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 | |