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};
 30
 31static int adc_joystick_handle(const void *data, void *private)
 32{
 33	struct adc_joystick *joy = private;
 34	enum iio_endian endianness;
 35	int bytes, msb, val, idx, i;
 36	const u16 *data_u16;
 37	bool sign;
 38
 39	bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
 40
 41	for (i = 0; i < joy->num_chans; ++i) {
 42		idx = joy->chans[i].channel->scan_index;
 43		endianness = joy->chans[i].channel->scan_type.endianness;
 44		msb = joy->chans[i].channel->scan_type.realbits - 1;
 45		sign = tolower(joy->chans[i].channel->scan_type.sign) == 's';
 46
 47		switch (bytes) {
 48		case 1:
 49			val = ((const u8 *)data)[idx];
 50			break;
 51		case 2:
 52			data_u16 = (const u16 *)data + idx;
 53
 54			/*
 55			 * Data is aligned to the sample size by IIO core.
 56			 * Call `get_unaligned_xe16` to hide type casting.
 57			 */
 58			if (endianness == IIO_BE)
 59				val = get_unaligned_be16(data_u16);
 60			else if (endianness == IIO_LE)
 61				val = get_unaligned_le16(data_u16);
 62			else /* IIO_CPU */
 63				val = *data_u16;
 64			break;
 65		default:
 66			return -EINVAL;
 67		}
 68
 69		val >>= joy->chans[i].channel->scan_type.shift;
 70		if (sign)
 71			val = sign_extend32(val, msb);
 72		else
 73			val &= GENMASK(msb, 0);
 74		input_report_abs(joy->input, joy->axes[i].code, val);
 75	}
 76
 77	input_sync(joy->input);
 78
 79	return 0;
 80}
 81
 82static int adc_joystick_open(struct input_dev *dev)
 83{
 84	struct adc_joystick *joy = input_get_drvdata(dev);
 85	struct device *devp = &dev->dev;
 86	int ret;
 87
 88	ret = iio_channel_start_all_cb(joy->buffer);
 89	if (ret)
 90		dev_err(devp, "Unable to start callback buffer: %d\n", ret);
 91
 92	return ret;
 93}
 94
 95static void adc_joystick_close(struct input_dev *dev)
 96{
 97	struct adc_joystick *joy = input_get_drvdata(dev);
 98
 99	iio_channel_stop_all_cb(joy->buffer);
100}
101
102static void adc_joystick_cleanup(void *data)
103{
104	iio_channel_release_all_cb(data);
105}
106
107static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
108{
109	struct adc_joystick_axis *axes;
110	struct fwnode_handle *child;
111	int num_axes, error, i;
112
113	num_axes = device_get_child_node_count(dev);
114	if (!num_axes) {
115		dev_err(dev, "Unable to find child nodes\n");
116		return -EINVAL;
117	}
118
119	if (num_axes != joy->num_chans) {
120		dev_err(dev, "Got %d child nodes for %d channels\n",
121			num_axes, joy->num_chans);
122		return -EINVAL;
123	}
124
125	axes = devm_kmalloc_array(dev, num_axes, sizeof(*axes), GFP_KERNEL);
126	if (!axes)
127		return -ENOMEM;
128
129	device_for_each_child_node(dev, child) {
130		error = fwnode_property_read_u32(child, "reg", &i);
131		if (error) {
132			dev_err(dev, "reg invalid or missing\n");
133			goto err_fwnode_put;
134		}
135
136		if (i >= num_axes) {
137			error = -EINVAL;
138			dev_err(dev, "No matching axis for reg %d\n", i);
139			goto err_fwnode_put;
140		}
141
142		error = fwnode_property_read_u32(child, "linux,code",
143						 &axes[i].code);
144		if (error) {
145			dev_err(dev, "linux,code invalid or missing\n");
146			goto err_fwnode_put;
147		}
148
149		error = fwnode_property_read_u32_array(child, "abs-range",
150						       axes[i].range, 2);
151		if (error) {
152			dev_err(dev, "abs-range invalid or missing\n");
153			goto err_fwnode_put;
154		}
155
156		fwnode_property_read_u32(child, "abs-fuzz", &axes[i].fuzz);
157		fwnode_property_read_u32(child, "abs-flat", &axes[i].flat);
158
159		input_set_abs_params(joy->input, axes[i].code,
160				     axes[i].range[0], axes[i].range[1],
161				     axes[i].fuzz, axes[i].flat);
162		input_set_capability(joy->input, EV_ABS, axes[i].code);
163	}
164
165	joy->axes = axes;
166
167	return 0;
168
169err_fwnode_put:
170	fwnode_handle_put(child);
171	return error;
172}
173
174static int adc_joystick_probe(struct platform_device *pdev)
175{
176	struct device *dev = &pdev->dev;
177	struct adc_joystick *joy;
178	struct input_dev *input;
179	int error;
180	int bits;
181	int i;
182
183	joy = devm_kzalloc(dev, sizeof(*joy), GFP_KERNEL);
184	if (!joy)
185		return -ENOMEM;
186
187	joy->chans = devm_iio_channel_get_all(dev);
188	if (IS_ERR(joy->chans)) {
189		error = PTR_ERR(joy->chans);
190		if (error != -EPROBE_DEFER)
191			dev_err(dev, "Unable to get IIO channels");
192		return error;
193	}
194
195	/* Count how many channels we got. NULL terminated. */
196	for (i = 0; joy->chans[i].indio_dev; i++) {
197		bits = joy->chans[i].channel->scan_type.storagebits;
198		if (!bits || bits > 16) {
199			dev_err(dev, "Unsupported channel storage size\n");
200			return -EINVAL;
201		}
202		if (bits != joy->chans[0].channel->scan_type.storagebits) {
203			dev_err(dev, "Channels must have equal storage size\n");
204			return -EINVAL;
205		}
206	}
207	joy->num_chans = i;
208
209	input = devm_input_allocate_device(dev);
210	if (!input) {
211		dev_err(dev, "Unable to allocate input device\n");
212		return -ENOMEM;
213	}
214
215	joy->input = input;
216	input->name = pdev->name;
217	input->id.bustype = BUS_HOST;
218	input->open = adc_joystick_open;
219	input->close = adc_joystick_close;
220
221	error = adc_joystick_set_axes(dev, joy);
222	if (error)
223		return error;
224
225	input_set_drvdata(input, joy);
226	error = input_register_device(input);
227	if (error) {
228		dev_err(dev, "Unable to register input device\n");
229		return error;
230	}
231
232	joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle, joy);
233	if (IS_ERR(joy->buffer)) {
234		dev_err(dev, "Unable to allocate callback buffer\n");
235		return PTR_ERR(joy->buffer);
236	}
237
238	error = devm_add_action_or_reset(dev, adc_joystick_cleanup, joy->buffer);
239	if (error)  {
240		dev_err(dev, "Unable to add action\n");
241		return error;
242	}
243
244	return 0;
245}
246
247static const struct of_device_id adc_joystick_of_match[] = {
248	{ .compatible = "adc-joystick", },
249	{ }
250};
251MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
252
253static struct platform_driver adc_joystick_driver = {
254	.driver = {
255		.name = "adc-joystick",
256		.of_match_table = adc_joystick_of_match,
257	},
258	.probe = adc_joystick_probe,
259};
260module_platform_driver(adc_joystick_driver);
261
262MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
263MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
264MODULE_LICENSE("GPL");