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 
16 struct adc_joystick_axis {
17 	u32 code;
18 	s32 range[2];
19 	s32 fuzz;
20 	s32 flat;
21 };
22 
23 struct 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 
adc_joystick_poll(struct input_dev * input)32 static 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 
adc_joystick_handle(const void * data,void * private)46 static 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 
adc_joystick_open(struct input_dev * dev)97 static 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 
adc_joystick_close(struct input_dev * dev)110 static 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 
adc_joystick_cleanup(void * data)117 static void adc_joystick_cleanup(void *data)
118 {
119 	iio_channel_release_all_cb(data);
120 }
121 
adc_joystick_set_axes(struct device * dev,struct adc_joystick * joy)122 static 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 
184 err_fwnode_put:
185 	fwnode_handle_put(child);
186 	return error;
187 }
188 
adc_joystick_probe(struct platform_device * pdev)189 static 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 
289 static const struct of_device_id adc_joystick_of_match[] = {
290 	{ .compatible = "adc-joystick", },
291 	{ }
292 };
293 MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
294 
295 static 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 };
302 module_platform_driver(adc_joystick_driver);
303 
304 MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
305 MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
306 MODULE_LICENSE("GPL");
307