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(dev: input);
35 int i, val, ret;
36
37 for (i = 0; i < joy->num_chans; i++) {
38 ret = iio_read_channel_raw(chan: &joy->chans[i], val: &val);
39 if (ret < 0)
40 return;
41 input_report_abs(dev: input, code: joy->axes[i].code, value: val);
42 }
43 input_sync(dev: 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(p: data_u16);
75 else if (endianness == IIO_LE)
76 val = get_unaligned_le16(p: 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(value: val, index: msb);
87 else
88 val &= GENMASK(msb, 0);
89 input_report_abs(dev: joy->input, code: joy->axes[i].code, value: val);
90 }
91
92 input_sync(dev: 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(cb_buff: 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(cb_buff: joy->buffer);
115}
116
117static void adc_joystick_cleanup(void *data)
118{
119 iio_channel_release_all_cb(cb_buffer: 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, n: num_axes, size: 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(fwnode: child, propname: "reg", val: &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(fwnode: child, propname: "linux,code",
158 val: &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(fwnode: child, propname: "abs-range",
165 val: axes[i].range, nval: 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(fwnode: child, propname: "abs-fuzz", val: &axes[i].fuzz);
172 fwnode_property_read_u32(fwnode: child, propname: "abs-flat", val: &axes[i].flat);
173
174 input_set_abs_params(dev: joy->input, axis: axes[i].code,
175 min: axes[i].range[0], max: axes[i].range[1],
176 fuzz: axes[i].fuzz, flat: axes[i].flat);
177 input_set_capability(dev: joy->input, EV_ABS, code: axes[i].code);
178 }
179
180 joy->axes = axes;
181
182 return 0;
183
184err_fwnode_put:
185 fwnode_handle_put(fwnode: 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, size: sizeof(*joy), GFP_KERNEL);
200 if (!joy)
201 return -ENOMEM;
202
203 joy->chans = devm_iio_channel_get_all(dev);
204 if (IS_ERR(ptr: joy->chans)) {
205 error = PTR_ERR(ptr: 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, propname: "poll-interval", val: &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(dev: input, poll_fn: adc_joystick_poll);
258 input_set_poll_interval(dev: input, interval: 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, cb: adc_joystick_handle,
264 private: joy);
265 if (IS_ERR(ptr: joy->buffer)) {
266 dev_err(dev, "Unable to allocate callback buffer\n");
267 return PTR_ERR(ptr: 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(dev: input, data: 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

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