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(fsia6b->dev, fsia6b_axes[i],
 92						 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(fsia6b->dev,
103							 sw_id++,
104							 sw_state == 0);
105					fallthrough;
106				case '2':
107					input_report_key(fsia6b->dev,
108							 sw_id++,
109							 sw_state == 1);
110					fallthrough;
111				case '1':
112					input_report_key(fsia6b->dev,
113							 sw_id++,
114							 sw_state == 2);
115				}
116			}
117			input_sync(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, 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	snprintf(fsia6b->phys, sizeof(fsia6b->phys), "%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(input_dev, fsia6b_axes[i],
164				     1000, 2000, 2, 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(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(input_dev);
193fail1:	serio_set_drvdata(serio, NULL);
194	kfree(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(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)