1// SPDX-License-Identifier: GPL-2.0
2/*
3 * FS-iA6B iBus RC receiver driver
4 *
5 * This driver provides all 14 channels of the FlySky FS-ia6B RC receiver
6 * as analog values.
7 *
8 * Additionally, the channels can be converted to discrete switch values.
9 * By default, it is configured for the offical FS-i6 remote control.
10 * If you use a different hardware configuration, you can configure it
11 * using the `switch_config` parameter.
12 */
13
14#include <linux/device.h>
15#include <linux/input.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/serio.h>
19#include <linux/slab.h>
20#include <linux/types.h>
21
22#define DRIVER_DESC "FS-iA6B iBus RC receiver"
23
24MODULE_AUTHOR("Markus Koch <markus@notsyncing.net>");
25MODULE_DESCRIPTION(DRIVER_DESC);
26MODULE_LICENSE("GPL");
27
28#define IBUS_SERVO_COUNT 14
29
30static char *switch_config = "00000022320000";
31module_param(switch_config, charp, 0444);
32MODULE_PARM_DESC(switch_config,
33 "Amount of switch positions per channel (14 characters, 0-3)");
34
35static int fsia6b_axes[IBUS_SERVO_COUNT] = {
36 ABS_X, ABS_Y,
37 ABS_Z, ABS_RX,
38 ABS_RY, ABS_RZ,
39 ABS_HAT0X, ABS_HAT0Y,
40 ABS_HAT1X, ABS_HAT1Y,
41 ABS_HAT2X, ABS_HAT2Y,
42 ABS_HAT3X, ABS_HAT3Y
43};
44
45enum ibus_state { SYNC, COLLECT, PROCESS };
46
47struct ibus_packet {
48 enum ibus_state state;
49
50 int offset;
51 u16 ibuf;
52 u16 channel[IBUS_SERVO_COUNT];
53};
54
55struct fsia6b {
56 struct input_dev *dev;
57 struct ibus_packet packet;
58
59 char phys[32];
60};
61
62static irqreturn_t fsia6b_serio_irq(struct serio *serio,
63 unsigned char data, unsigned int flags)
64{
65 struct fsia6b *fsia6b = serio_get_drvdata(serio);
66 int i;
67 int sw_state;
68 int sw_id = BTN_0;
69
70 fsia6b->packet.ibuf = (data << 8) | ((fsia6b->packet.ibuf >> 8) & 0xFF);
71
72 switch (fsia6b->packet.state) {
73 case SYNC:
74 if (fsia6b->packet.ibuf == 0x4020)
75 fsia6b->packet.state = COLLECT;
76 break;
77
78 case COLLECT:
79 fsia6b->packet.state = PROCESS;
80 break;
81
82 case PROCESS:
83 fsia6b->packet.channel[fsia6b->packet.offset] =
84 fsia6b->packet.ibuf;
85 fsia6b->packet.offset++;
86
87 if (fsia6b->packet.offset == IBUS_SERVO_COUNT) {
88 fsia6b->packet.offset = 0;
89 fsia6b->packet.state = SYNC;
90 for (i = 0; i < IBUS_SERVO_COUNT; ++i) {
91 input_report_abs(dev: fsia6b->dev, code: fsia6b_axes[i],
92 value: fsia6b->packet.channel[i]);
93
94 sw_state = 0;
95 if (fsia6b->packet.channel[i] > 1900)
96 sw_state = 1;
97 else if (fsia6b->packet.channel[i] < 1100)
98 sw_state = 2;
99
100 switch (switch_config[i]) {
101 case '3':
102 input_report_key(dev: fsia6b->dev,
103 code: sw_id++,
104 value: sw_state == 0);
105 fallthrough;
106 case '2':
107 input_report_key(dev: fsia6b->dev,
108 code: sw_id++,
109 value: sw_state == 1);
110 fallthrough;
111 case '1':
112 input_report_key(dev: fsia6b->dev,
113 code: sw_id++,
114 value: sw_state == 2);
115 }
116 }
117 input_sync(dev: fsia6b->dev);
118 } else {
119 fsia6b->packet.state = COLLECT;
120 }
121 break;
122 }
123
124 return IRQ_HANDLED;
125}
126
127static int fsia6b_serio_connect(struct serio *serio, struct serio_driver *drv)
128{
129 struct fsia6b *fsia6b;
130 struct input_dev *input_dev;
131 int err;
132 int i, j;
133 int sw_id = 0;
134
135 fsia6b = kzalloc(sizeof(*fsia6b), GFP_KERNEL);
136 if (!fsia6b)
137 return -ENOMEM;
138
139 fsia6b->packet.ibuf = 0;
140 fsia6b->packet.offset = 0;
141 fsia6b->packet.state = SYNC;
142
143 serio_set_drvdata(serio, data: fsia6b);
144
145 input_dev = input_allocate_device();
146 if (!input_dev) {
147 err = -ENOMEM;
148 goto fail1;
149 }
150 fsia6b->dev = input_dev;
151
152 scnprintf(buf: fsia6b->phys, size: sizeof(fsia6b->phys), fmt: "%s/input0", serio->phys);
153
154 input_dev->name = DRIVER_DESC;
155 input_dev->phys = fsia6b->phys;
156 input_dev->id.bustype = BUS_RS232;
157 input_dev->id.vendor = SERIO_FSIA6B;
158 input_dev->id.product = serio->id.id;
159 input_dev->id.version = 0x0100;
160 input_dev->dev.parent = &serio->dev;
161
162 for (i = 0; i < IBUS_SERVO_COUNT; i++)
163 input_set_abs_params(dev: input_dev, axis: fsia6b_axes[i],
164 min: 1000, max: 2000, fuzz: 2, flat: 2);
165
166 /* Register switch configuration */
167 for (i = 0; i < IBUS_SERVO_COUNT; i++) {
168 if (switch_config[i] < '0' || switch_config[i] > '3') {
169 dev_err(&fsia6b->dev->dev,
170 "Invalid switch configuration supplied for fsia6b.\n");
171 err = -EINVAL;
172 goto fail2;
173 }
174
175 for (j = '1'; j <= switch_config[i]; j++) {
176 input_set_capability(dev: input_dev, EV_KEY, BTN_0 + sw_id);
177 sw_id++;
178 }
179 }
180
181 err = serio_open(serio, drv);
182 if (err)
183 goto fail2;
184
185 err = input_register_device(fsia6b->dev);
186 if (err)
187 goto fail3;
188
189 return 0;
190
191fail3: serio_close(serio);
192fail2: input_free_device(dev: input_dev);
193fail1: serio_set_drvdata(serio, NULL);
194 kfree(objp: fsia6b);
195 return err;
196}
197
198static void fsia6b_serio_disconnect(struct serio *serio)
199{
200 struct fsia6b *fsia6b = serio_get_drvdata(serio);
201
202 serio_close(serio);
203 serio_set_drvdata(serio, NULL);
204 input_unregister_device(fsia6b->dev);
205 kfree(objp: fsia6b);
206}
207
208static const struct serio_device_id fsia6b_serio_ids[] = {
209 {
210 .type = SERIO_RS232,
211 .proto = SERIO_FSIA6B,
212 .id = SERIO_ANY,
213 .extra = SERIO_ANY,
214 },
215 { 0 }
216};
217
218MODULE_DEVICE_TABLE(serio, fsia6b_serio_ids);
219
220static struct serio_driver fsia6b_serio_drv = {
221 .driver = {
222 .name = "fsia6b"
223 },
224 .description = DRIVER_DESC,
225 .id_table = fsia6b_serio_ids,
226 .interrupt = fsia6b_serio_irq,
227 .connect = fsia6b_serio_connect,
228 .disconnect = fsia6b_serio_disconnect
229};
230
231module_serio_driver(fsia6b_serio_drv)
232

source code of linux/drivers/input/joystick/fsia6b.c