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(input);
 41	int i, val, ret;
 42
 43	for (i = 0; i < joy->num_chans; i++) {
 44		ret = iio_read_channel_raw(&joy->chans[i], &val);
 45		if (ret < 0)
 46			return;
 47		if (joy->axes[i].inverted)
 48			val = adc_joystick_invert(input, i, val);
 49		input_report_abs(input, joy->axes[i].code, val);
 50	}
 51	input_sync(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(data_u16);
 83			else if (endianness == IIO_LE)
 84				val = get_unaligned_le16(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(val, msb);
 95		else
 96			val &= GENMASK(msb, 0);
 97		if (joy->axes[i].inverted)
 98			val = adc_joystick_invert(joy->input, i, val);
 99		input_report_abs(joy->input, joy->axes[i].code, val);
100	}
101
102	input_sync(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(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(joy->buffer);
125}
126
127static void adc_joystick_cleanup(void *data)
128{
129	iio_channel_release_all_cb(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(child, "reg", &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(child, "linux,code",
164						 &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(child, "abs-range",
171						       range, 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(child, "abs-fuzz", &fuzz))
184			fuzz = 0;
185
186		if (fwnode_property_read_u32(child, "abs-flat", &flat))
187			flat = 0;
188
189		input_set_abs_params(joy->input, axes[i].code,
190				     range[0], 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(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, "poll-interval", &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, poll_interval != 0,
256					    &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(input, adc_joystick_poll);
283		input_set_poll_interval(input, 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, adc_joystick_handle,
289						     joy);
290		if (IS_ERR(joy->buffer)) {
291			dev_err(dev, "Unable to allocate callback buffer\n");
292			return PTR_ERR(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(input, 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");