1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Input driver for joysticks connected over ADC.
4 * Copyright (c) 2019-2020 Artur Rojek <contact@artur-rojek.eu>
5 */
6#include <linux/ctype.h>
7#include <linux/input.h>
8#include <linux/iio/iio.h>
9#include <linux/iio/consumer.h>
10#include <linux/module.h>
11#include <linux/platform_device.h>
12#include <linux/property.h>
13
14#include <asm/unaligned.h>
15
16struct adc_joystick_axis {
17	u32 code;
18	s32 range[2];
19	s32 fuzz;
20	s32 flat;
21};
22
23struct adc_joystick {
24	struct input_dev *input;
25	struct iio_cb_buffer *buffer;
26	struct adc_joystick_axis *axes;
27	struct iio_channel *chans;
28	int num_chans;
29	bool polled;
30};
31
32static void adc_joystick_poll(struct input_dev *input)
33{
34	struct adc_joystick *joy = input_get_drvdata(input);
35	int i, val, ret;
36
37	for (i = 0; i < joy->num_chans; i++) {
38		ret = iio_read_channel_raw(&joy->chans[i], &val);
39		if (ret < 0)
40			return;
41		input_report_abs(input, joy->axes[i].code, val);
42	}
43	input_sync(input);
44}
45
46static int adc_joystick_handle(const void *data, void *private)
47{
48	struct adc_joystick *joy = private;
49	enum iio_endian endianness;
50	int bytes, msb, val, idx, i;
51	const u16 *data_u16;
52	bool sign;
53
54	bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
55
56	for (i = 0; i < joy->num_chans; ++i) {
57		idx = joy->chans[i].channel->scan_index;
58		endianness = joy->chans[i].channel->scan_type.endianness;
59		msb = joy->chans[i].channel->scan_type.realbits - 1;
60		sign = tolower(joy->chans[i].channel->scan_type.sign) == 's';
61
62		switch (bytes) {
63		case 1:
64			val = ((const u8 *)data)[idx];
65			break;
66		case 2:
67			data_u16 = (const u16 *)data + idx;
68
69			/*
70			 * Data is aligned to the sample size by IIO core.
71			 * Call `get_unaligned_xe16` to hide type casting.
72			 */
73			if (endianness == IIO_BE)
74				val = get_unaligned_be16(data_u16);
75			else if (endianness == IIO_LE)
76				val = get_unaligned_le16(data_u16);
77			else /* IIO_CPU */
78				val = *data_u16;
79			break;
80		default:
81			return -EINVAL;
82		}
83
84		val >>= joy->chans[i].channel->scan_type.shift;
85		if (sign)
86			val = sign_extend32(val, msb);
87		else
88			val &= GENMASK(msb, 0);
89		input_report_abs(joy->input, joy->axes[i].code, val);
90	}
91
92	input_sync(joy->input);
93
94	return 0;
95}
96
97static int adc_joystick_open(struct input_dev *dev)
98{
99	struct adc_joystick *joy = input_get_drvdata(dev);
100	struct device *devp = &dev->dev;
101	int ret;
102
103	ret = iio_channel_start_all_cb(joy->buffer);
104	if (ret)
105		dev_err(devp, "Unable to start callback buffer: %d\n", ret);
106
107	return ret;
108}
109
110static void adc_joystick_close(struct input_dev *dev)
111{
112	struct adc_joystick *joy = input_get_drvdata(dev);
113
114	iio_channel_stop_all_cb(joy->buffer);
115}
116
117static void adc_joystick_cleanup(void *data)
118{
119	iio_channel_release_all_cb(data);
120}
121
122static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
123{
124	struct adc_joystick_axis *axes;
125	struct fwnode_handle *child;
126	int num_axes, error, i;
127
128	num_axes = device_get_child_node_count(dev);
129	if (!num_axes) {
130		dev_err(dev, "Unable to find child nodes\n");
131		return -EINVAL;
132	}
133
134	if (num_axes != joy->num_chans) {
135		dev_err(dev, "Got %d child nodes for %d channels\n",
136			num_axes, joy->num_chans);
137		return -EINVAL;
138	}
139
140	axes = devm_kmalloc_array(dev, num_axes, sizeof(*axes), GFP_KERNEL);
141	if (!axes)
142		return -ENOMEM;
143
144	device_for_each_child_node(dev, child) {
145		error = fwnode_property_read_u32(child, "reg", &i);
146		if (error) {
147			dev_err(dev, "reg invalid or missing\n");
148			goto err_fwnode_put;
149		}
150
151		if (i >= num_axes) {
152			error = -EINVAL;
153			dev_err(dev, "No matching axis for reg %d\n", i);
154			goto err_fwnode_put;
155		}
156
157		error = fwnode_property_read_u32(child, "linux,code",
158						 &axes[i].code);
159		if (error) {
160			dev_err(dev, "linux,code invalid or missing\n");
161			goto err_fwnode_put;
162		}
163
164		error = fwnode_property_read_u32_array(child, "abs-range",
165						       axes[i].range, 2);
166		if (error) {
167			dev_err(dev, "abs-range invalid or missing\n");
168			goto err_fwnode_put;
169		}
170
171		fwnode_property_read_u32(child, "abs-fuzz", &axes[i].fuzz);
172		fwnode_property_read_u32(child, "abs-flat", &axes[i].flat);
173
174		input_set_abs_params(joy->input, axes[i].code,
175				     axes[i].range[0], axes[i].range[1],
176				     axes[i].fuzz, axes[i].flat);
177		input_set_capability(joy->input, EV_ABS, axes[i].code);
178	}
179
180	joy->axes = axes;
181
182	return 0;
183
184err_fwnode_put:
185	fwnode_handle_put(child);
186	return error;
187}
188
189static int adc_joystick_probe(struct platform_device *pdev)
190{
191	struct device *dev = &pdev->dev;
192	struct adc_joystick *joy;
193	struct input_dev *input;
194	int error;
195	int bits;
196	int i;
197	unsigned int poll_interval;
198
199	joy = devm_kzalloc(dev, sizeof(*joy), GFP_KERNEL);
200	if (!joy)
201		return -ENOMEM;
202
203	joy->chans = devm_iio_channel_get_all(dev);
204	if (IS_ERR(joy->chans)) {
205		error = PTR_ERR(joy->chans);
206		if (error != -EPROBE_DEFER)
207			dev_err(dev, "Unable to get IIO channels");
208		return error;
209	}
210
211	error = device_property_read_u32(dev, "poll-interval", &poll_interval);
212	if (error) {
213		/* -EINVAL means the property is absent. */
214		if (error != -EINVAL)
215			return error;
216	} else if (poll_interval == 0) {
217		dev_err(dev, "Unable to get poll-interval\n");
218		return -EINVAL;
219	} else {
220		joy->polled = true;
221	}
222
223	/*
224	 * Count how many channels we got. NULL terminated.
225	 * Do not check the storage size if using polling.
226	 */
227	for (i = 0; joy->chans[i].indio_dev; i++) {
228		if (joy->polled)
229			continue;
230		bits = joy->chans[i].channel->scan_type.storagebits;
231		if (!bits || bits > 16) {
232			dev_err(dev, "Unsupported channel storage size\n");
233			return -EINVAL;
234		}
235		if (bits != joy->chans[0].channel->scan_type.storagebits) {
236			dev_err(dev, "Channels must have equal storage size\n");
237			return -EINVAL;
238		}
239	}
240	joy->num_chans = i;
241
242	input = devm_input_allocate_device(dev);
243	if (!input) {
244		dev_err(dev, "Unable to allocate input device\n");
245		return -ENOMEM;
246	}
247
248	joy->input = input;
249	input->name = pdev->name;
250	input->id.bustype = BUS_HOST;
251
252	error = adc_joystick_set_axes(dev, joy);
253	if (error)
254		return error;
255
256	if (joy->polled) {
257		input_setup_polling(input, adc_joystick_poll);
258		input_set_poll_interval(input, poll_interval);
259	} else {
260		input->open = adc_joystick_open;
261		input->close = adc_joystick_close;
262
263		joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle,
264						     joy);
265		if (IS_ERR(joy->buffer)) {
266			dev_err(dev, "Unable to allocate callback buffer\n");
267			return PTR_ERR(joy->buffer);
268		}
269
270		error = devm_add_action_or_reset(dev, adc_joystick_cleanup,
271						 joy->buffer);
272		if (error)  {
273			dev_err(dev, "Unable to add action\n");
274			return error;
275		}
276	}
277
278	input_set_drvdata(input, joy);
279
280	error = input_register_device(input);
281	if (error) {
282		dev_err(dev, "Unable to register input device\n");
283		return error;
284	}
285
286	return 0;
287}
288
289static const struct of_device_id adc_joystick_of_match[] = {
290	{ .compatible = "adc-joystick", },
291	{ }
292};
293MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
294
295static struct platform_driver adc_joystick_driver = {
296	.driver = {
297		.name = "adc-joystick",
298		.of_match_table = adc_joystick_of_match,
299	},
300	.probe = adc_joystick_probe,
301};
302module_platform_driver(adc_joystick_driver);
303
304MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
305MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
306MODULE_LICENSE("GPL");
307