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 <linux/unaligned.h>
15
16struct adc_joystick_axis {
17 u32 code;
18 bool inverted;
19};
20
21struct adc_joystick {
22 struct input_dev *input;
23 struct iio_cb_buffer *buffer;
24 struct iio_channel *chans;
25 unsigned int num_chans;
26 struct adc_joystick_axis axes[] __counted_by(num_chans);
27};
28
29static int adc_joystick_invert(struct input_dev *dev,
30 unsigned int axis, int val)
31{
32 int min = input_abs_get_min(dev, axis);
33 int max = input_abs_get_max(dev, axis);
34
35 return (max + min) - val;
36}
37
38static void adc_joystick_poll(struct input_dev *input)
39{
40 struct adc_joystick *joy = input_get_drvdata(dev: input);
41 int i, val, ret;
42
43 for (i = 0; i < joy->num_chans; i++) {
44 ret = iio_read_channel_raw(chan: &joy->chans[i], val: &val);
45 if (ret < 0)
46 return;
47 if (joy->axes[i].inverted)
48 val = adc_joystick_invert(dev: input, axis: i, val);
49 input_report_abs(dev: input, code: joy->axes[i].code, value: val);
50 }
51 input_sync(dev: input);
52}
53
54static int adc_joystick_handle(const void *data, void *private)
55{
56 struct adc_joystick *joy = private;
57 enum iio_endian endianness;
58 int bytes, msb, val, idx, i;
59 const u16 *data_u16;
60 bool sign;
61
62 bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
63
64 for (i = 0; i < joy->num_chans; ++i) {
65 idx = joy->chans[i].channel->scan_index;
66 endianness = joy->chans[i].channel->scan_type.endianness;
67 msb = joy->chans[i].channel->scan_type.realbits - 1;
68 sign = tolower(joy->chans[i].channel->scan_type.sign) == 's';
69
70 switch (bytes) {
71 case 1:
72 val = ((const u8 *)data)[idx];
73 break;
74 case 2:
75 data_u16 = (const u16 *)data + idx;
76
77 /*
78 * Data is aligned to the sample size by IIO core.
79 * Call `get_unaligned_xe16` to hide type casting.
80 */
81 if (endianness == IIO_BE)
82 val = get_unaligned_be16(p: data_u16);
83 else if (endianness == IIO_LE)
84 val = get_unaligned_le16(p: data_u16);
85 else /* IIO_CPU */
86 val = *data_u16;
87 break;
88 default:
89 return -EINVAL;
90 }
91
92 val >>= joy->chans[i].channel->scan_type.shift;
93 if (sign)
94 val = sign_extend32(value: val, index: msb);
95 else
96 val &= GENMASK(msb, 0);
97 if (joy->axes[i].inverted)
98 val = adc_joystick_invert(dev: joy->input, axis: i, val);
99 input_report_abs(dev: joy->input, code: joy->axes[i].code, value: val);
100 }
101
102 input_sync(dev: joy->input);
103
104 return 0;
105}
106
107static int adc_joystick_open(struct input_dev *dev)
108{
109 struct adc_joystick *joy = input_get_drvdata(dev);
110 struct device *devp = &dev->dev;
111 int ret;
112
113 ret = iio_channel_start_all_cb(cb_buff: joy->buffer);
114 if (ret)
115 dev_err(devp, "Unable to start callback buffer: %d\n", ret);
116
117 return ret;
118}
119
120static void adc_joystick_close(struct input_dev *dev)
121{
122 struct adc_joystick *joy = input_get_drvdata(dev);
123
124 iio_channel_stop_all_cb(cb_buff: joy->buffer);
125}
126
127static void adc_joystick_cleanup(void *data)
128{
129 iio_channel_release_all_cb(cb_buffer: data);
130}
131
132static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
133{
134 struct adc_joystick_axis *axes = joy->axes;
135 s32 range[2], fuzz, flat;
136 unsigned int num_axes;
137 int error, i;
138
139 num_axes = device_get_child_node_count(dev);
140 if (!num_axes) {
141 dev_err(dev, "Unable to find child nodes\n");
142 return -EINVAL;
143 }
144
145 if (num_axes != joy->num_chans) {
146 dev_err(dev, "Got %d child nodes for %d channels\n",
147 num_axes, joy->num_chans);
148 return -EINVAL;
149 }
150
151 device_for_each_child_node_scoped(dev, child) {
152 error = fwnode_property_read_u32(fwnode: child, propname: "reg", val: &i);
153 if (error) {
154 dev_err(dev, "reg invalid or missing\n");
155 return error;
156 }
157
158 if (i >= num_axes) {
159 dev_err(dev, "No matching axis for reg %d\n", i);
160 return -EINVAL;
161 }
162
163 error = fwnode_property_read_u32(fwnode: child, propname: "linux,code",
164 val: &axes[i].code);
165 if (error) {
166 dev_err(dev, "linux,code invalid or missing\n");
167 return error;
168 }
169
170 error = fwnode_property_read_u32_array(fwnode: child, propname: "abs-range",
171 val: range, nval: 2);
172 if (error) {
173 dev_err(dev, "abs-range invalid or missing\n");
174 return error;
175 }
176
177 if (range[0] > range[1]) {
178 dev_dbg(dev, "abs-axis %d inverted\n", i);
179 axes[i].inverted = true;
180 swap(range[0], range[1]);
181 }
182
183 if (fwnode_property_read_u32(fwnode: child, propname: "abs-fuzz", val: &fuzz))
184 fuzz = 0;
185
186 if (fwnode_property_read_u32(fwnode: child, propname: "abs-flat", val: &flat))
187 flat = 0;
188
189 input_set_abs_params(dev: joy->input, axis: axes[i].code,
190 min: range[0], max: range[1], fuzz, flat);
191 }
192
193 return 0;
194}
195
196
197static int adc_joystick_count_channels(struct device *dev,
198 const struct iio_channel *chans,
199 bool polled,
200 unsigned int *num_chans)
201{
202 int bits;
203 int i;
204
205 /*
206 * Count how many channels we got. NULL terminated.
207 * Do not check the storage size if using polling.
208 */
209 for (i = 0; chans[i].indio_dev; i++) {
210 if (polled)
211 continue;
212 bits = chans[i].channel->scan_type.storagebits;
213 if (!bits || bits > 16) {
214 dev_err(dev, "Unsupported channel storage size\n");
215 return -EINVAL;
216 }
217 if (bits != chans[0].channel->scan_type.storagebits) {
218 dev_err(dev, "Channels must have equal storage size\n");
219 return -EINVAL;
220 }
221 }
222
223 *num_chans = i;
224 return 0;
225}
226
227static int adc_joystick_probe(struct platform_device *pdev)
228{
229 struct device *dev = &pdev->dev;
230 struct iio_channel *chans;
231 struct adc_joystick *joy;
232 struct input_dev *input;
233 unsigned int poll_interval = 0;
234 unsigned int num_chans;
235 int error;
236
237 chans = devm_iio_channel_get_all(dev);
238 error = PTR_ERR_OR_ZERO(ptr: chans);
239 if (error) {
240 if (error != -EPROBE_DEFER)
241 dev_err(dev, "Unable to get IIO channels");
242 return error;
243 }
244
245 error = device_property_read_u32(dev, propname: "poll-interval", val: &poll_interval);
246 if (error) {
247 /* -EINVAL means the property is absent. */
248 if (error != -EINVAL)
249 return error;
250 } else if (poll_interval == 0) {
251 dev_err(dev, "Unable to get poll-interval\n");
252 return -EINVAL;
253 }
254
255 error = adc_joystick_count_channels(dev, chans, polled: poll_interval != 0,
256 num_chans: &num_chans);
257 if (error)
258 return error;
259
260 joy = devm_kzalloc(dev, struct_size(joy, axes, num_chans), GFP_KERNEL);
261 if (!joy)
262 return -ENOMEM;
263
264 joy->chans = chans;
265 joy->num_chans = num_chans;
266
267 input = devm_input_allocate_device(dev);
268 if (!input) {
269 dev_err(dev, "Unable to allocate input device\n");
270 return -ENOMEM;
271 }
272
273 joy->input = input;
274 input->name = pdev->name;
275 input->id.bustype = BUS_HOST;
276
277 error = adc_joystick_set_axes(dev, joy);
278 if (error)
279 return error;
280
281 if (poll_interval != 0) {
282 input_setup_polling(dev: input, poll_fn: adc_joystick_poll);
283 input_set_poll_interval(dev: input, interval: poll_interval);
284 } else {
285 input->open = adc_joystick_open;
286 input->close = adc_joystick_close;
287
288 joy->buffer = iio_channel_get_all_cb(dev, cb: adc_joystick_handle,
289 private: joy);
290 if (IS_ERR(ptr: joy->buffer)) {
291 dev_err(dev, "Unable to allocate callback buffer\n");
292 return PTR_ERR(ptr: joy->buffer);
293 }
294
295 error = devm_add_action_or_reset(dev, adc_joystick_cleanup,
296 joy->buffer);
297 if (error) {
298 dev_err(dev, "Unable to add action\n");
299 return error;
300 }
301 }
302
303 input_set_drvdata(dev: input, data: joy);
304
305 error = input_register_device(input);
306 if (error) {
307 dev_err(dev, "Unable to register input device\n");
308 return error;
309 }
310
311 return 0;
312}
313
314static const struct of_device_id adc_joystick_of_match[] = {
315 { .compatible = "adc-joystick", },
316 { }
317};
318MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
319
320static struct platform_driver adc_joystick_driver = {
321 .driver = {
322 .name = "adc-joystick",
323 .of_match_table = adc_joystick_of_match,
324 },
325 .probe = adc_joystick_probe,
326};
327module_platform_driver(adc_joystick_driver);
328
329MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
330MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
331MODULE_LICENSE("GPL");
332

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source code of linux/drivers/input/joystick/adc-joystick.c