1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * drivers/input/touchscreen/tsc2007.c
4  *
5  * Copyright (c) 2008 MtekVision Co., Ltd.
6  *	Kwangwoo Lee <kwlee@mtekvision.com>
7  *
8  * Using code from:
9  *  - ads7846.c
10  *	Copyright (c) 2005 David Brownell
11  *	Copyright (c) 2006 Nokia Corporation
12  *  - corgi_ts.c
13  *	Copyright (C) 2004-2005 Richard Purdie
14  *  - omap_ts.[hc], ads7846.h, ts_osk.c
15  *	Copyright (C) 2002 MontaVista Software
16  *	Copyright (C) 2004 Texas Instruments
17  *	Copyright (C) 2005 Dirk Behme
18  */
19 
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <linux/gpio/consumer.h>
23 #include <linux/input.h>
24 #include <linux/interrupt.h>
25 #include <linux/i2c.h>
26 #include <linux/mod_devicetable.h>
27 #include <linux/property.h>
28 #include <linux/platform_data/tsc2007.h>
29 #include "tsc2007.h"
30 
31 int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
32 {
33 	s32 data;
34 	u16 val;
35 
36 	data = i2c_smbus_read_word_data(tsc->client, cmd);
37 	if (data < 0) {
38 		dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
39 		return data;
40 	}
41 
42 	/* The protocol and raw data format from i2c interface:
43 	 * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
44 	 * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
45 	 */
46 	val = swab16(data) >> 4;
47 
48 	dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);
49 
50 	return val;
51 }
52 
53 static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
54 {
55 	/* y- still on; turn on only y+ (and ADC) */
56 	tc->y = tsc2007_xfer(tsc, READ_Y);
57 
58 	/* turn y- off, x+ on, then leave in lowpower */
59 	tc->x = tsc2007_xfer(tsc, READ_X);
60 
61 	/* turn y+ off, x- on; we'll use formula #1 */
62 	tc->z1 = tsc2007_xfer(tsc, READ_Z1);
63 	tc->z2 = tsc2007_xfer(tsc, READ_Z2);
64 
65 	/* Prepare for next touch reading - power down ADC, enable PENIRQ */
66 	tsc2007_xfer(tsc, PWRDOWN);
67 }
68 
69 u32 tsc2007_calculate_resistance(struct tsc2007 *tsc, struct ts_event *tc)
70 {
71 	u32 rt = 0;
72 
73 	/* range filtering */
74 	if (tc->x == MAX_12BIT)
75 		tc->x = 0;
76 
77 	if (likely(tc->x && tc->z1)) {
78 		/* compute touch resistance using equation #1 */
79 		rt = tc->z2 - tc->z1;
80 		rt *= tc->x;
81 		rt *= tsc->x_plate_ohms;
82 		rt /= tc->z1;
83 		rt = (rt + 2047) >> 12;
84 	}
85 
86 	return rt;
87 }
88 
89 bool tsc2007_is_pen_down(struct tsc2007 *ts)
90 {
91 	/*
92 	 * NOTE: We can't rely on the pressure to determine the pen down
93 	 * state, even though this controller has a pressure sensor.
94 	 * The pressure value can fluctuate for quite a while after
95 	 * lifting the pen and in some cases may not even settle at the
96 	 * expected value.
97 	 *
98 	 * The only safe way to check for the pen up condition is in the
99 	 * work function by reading the pen signal state (it's a GPIO
100 	 * and IRQ). Unfortunately such callback is not always available,
101 	 * in that case we assume that the pen is down and expect caller
102 	 * to fall back on the pressure reading.
103 	 */
104 
105 	if (!ts->get_pendown_state)
106 		return true;
107 
108 	return ts->get_pendown_state(&ts->client->dev);
109 }
110 
111 static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
112 {
113 	struct tsc2007 *ts = handle;
114 	struct input_dev *input = ts->input;
115 	struct ts_event tc;
116 	u32 rt;
117 
118 	while (!ts->stopped && tsc2007_is_pen_down(ts)) {
119 
120 		/* pen is down, continue with the measurement */
121 
122 		mutex_lock(&ts->mlock);
123 		tsc2007_read_values(ts, &tc);
124 		mutex_unlock(&ts->mlock);
125 
126 		rt = tsc2007_calculate_resistance(ts, &tc);
127 
128 		if (!rt && !ts->get_pendown_state) {
129 			/*
130 			 * If pressure reported is 0 and we don't have
131 			 * callback to check pendown state, we have to
132 			 * assume that pen was lifted up.
133 			 */
134 			break;
135 		}
136 
137 		if (rt <= ts->max_rt) {
138 			dev_dbg(&ts->client->dev,
139 				"DOWN point(%4d,%4d), resistance (%4u)\n",
140 				tc.x, tc.y, rt);
141 
142 			rt = ts->max_rt - rt;
143 
144 			input_report_key(input, BTN_TOUCH, 1);
145 			input_report_abs(input, ABS_X, tc.x);
146 			input_report_abs(input, ABS_Y, tc.y);
147 			input_report_abs(input, ABS_PRESSURE, rt);
148 
149 			input_sync(input);
150 
151 		} else {
152 			/*
153 			 * Sample found inconsistent by debouncing or pressure is
154 			 * beyond the maximum. Don't report it to user space,
155 			 * repeat at least once more the measurement.
156 			 */
157 			dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
158 		}
159 
160 		wait_event_timeout(ts->wait, ts->stopped, ts->poll_period);
161 	}
162 
163 	dev_dbg(&ts->client->dev, "UP\n");
164 
165 	input_report_key(input, BTN_TOUCH, 0);
166 	input_report_abs(input, ABS_PRESSURE, 0);
167 	input_sync(input);
168 
169 	if (ts->clear_penirq)
170 		ts->clear_penirq();
171 
172 	return IRQ_HANDLED;
173 }
174 
175 static void tsc2007_stop(struct tsc2007 *ts)
176 {
177 	ts->stopped = true;
178 	mb();
179 	wake_up(&ts->wait);
180 
181 	disable_irq(ts->irq);
182 }
183 
184 static int tsc2007_open(struct input_dev *input_dev)
185 {
186 	struct tsc2007 *ts = input_get_drvdata(input_dev);
187 	int err;
188 
189 	ts->stopped = false;
190 	mb();
191 
192 	enable_irq(ts->irq);
193 
194 	/* Prepare for touch readings - power down ADC and enable PENIRQ */
195 	err = tsc2007_xfer(ts, PWRDOWN);
196 	if (err < 0) {
197 		tsc2007_stop(ts);
198 		return err;
199 	}
200 
201 	return 0;
202 }
203 
204 static void tsc2007_close(struct input_dev *input_dev)
205 {
206 	struct tsc2007 *ts = input_get_drvdata(input_dev);
207 
208 	tsc2007_stop(ts);
209 }
210 
211 static int tsc2007_get_pendown_state_gpio(struct device *dev)
212 {
213 	struct i2c_client *client = to_i2c_client(dev);
214 	struct tsc2007 *ts = i2c_get_clientdata(client);
215 
216 	return gpiod_get_value_cansleep(ts->gpiod);
217 }
218 
219 static int tsc2007_probe_properties(struct device *dev, struct tsc2007 *ts)
220 {
221 	u32 val32;
222 	u64 val64;
223 
224 	if (!device_property_read_u32(dev, "ti,max-rt", &val32))
225 		ts->max_rt = val32;
226 	else
227 		ts->max_rt = MAX_12BIT;
228 
229 	if (!device_property_read_u32(dev, "ti,fuzzx", &val32))
230 		ts->fuzzx = val32;
231 
232 	if (!device_property_read_u32(dev, "ti,fuzzy", &val32))
233 		ts->fuzzy = val32;
234 
235 	if (!device_property_read_u32(dev, "ti,fuzzz", &val32))
236 		ts->fuzzz = val32;
237 
238 	if (!device_property_read_u64(dev, "ti,poll-period", &val64))
239 		ts->poll_period = msecs_to_jiffies(val64);
240 	else
241 		ts->poll_period = msecs_to_jiffies(1);
242 
243 	if (!device_property_read_u32(dev, "ti,x-plate-ohms", &val32)) {
244 		ts->x_plate_ohms = val32;
245 	} else {
246 		dev_err(dev, "Missing ti,x-plate-ohms device property\n");
247 		return -EINVAL;
248 	}
249 
250 	ts->gpiod = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);
251 	if (IS_ERR(ts->gpiod))
252 		return PTR_ERR(ts->gpiod);
253 
254 	if (ts->gpiod)
255 		ts->get_pendown_state = tsc2007_get_pendown_state_gpio;
256 	else
257 		dev_warn(dev, "Pen down GPIO is not specified in properties\n");
258 
259 	return 0;
260 }
261 
262 static int tsc2007_probe_pdev(struct device *dev, struct tsc2007 *ts,
263 			      const struct tsc2007_platform_data *pdata,
264 			      const struct i2c_device_id *id)
265 {
266 	ts->model             = pdata->model;
267 	ts->x_plate_ohms      = pdata->x_plate_ohms;
268 	ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
269 	ts->poll_period       = msecs_to_jiffies(pdata->poll_period ? : 1);
270 	ts->get_pendown_state = pdata->get_pendown_state;
271 	ts->clear_penirq      = pdata->clear_penirq;
272 	ts->fuzzx             = pdata->fuzzx;
273 	ts->fuzzy             = pdata->fuzzy;
274 	ts->fuzzz             = pdata->fuzzz;
275 
276 	if (pdata->x_plate_ohms == 0) {
277 		dev_err(dev, "x_plate_ohms is not set up in platform data\n");
278 		return -EINVAL;
279 	}
280 
281 	return 0;
282 }
283 
284 static void tsc2007_call_exit_platform_hw(void *data)
285 {
286 	struct device *dev = data;
287 	const struct tsc2007_platform_data *pdata = dev_get_platdata(dev);
288 
289 	pdata->exit_platform_hw();
290 }
291 
292 static int tsc2007_probe(struct i2c_client *client)
293 {
294 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
295 	const struct tsc2007_platform_data *pdata =
296 		dev_get_platdata(&client->dev);
297 	struct tsc2007 *ts;
298 	struct input_dev *input_dev;
299 	int err;
300 
301 	if (!i2c_check_functionality(client->adapter,
302 				     I2C_FUNC_SMBUS_READ_WORD_DATA))
303 		return -EIO;
304 
305 	ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
306 	if (!ts)
307 		return -ENOMEM;
308 
309 	if (pdata)
310 		err = tsc2007_probe_pdev(&client->dev, ts, pdata, id);
311 	else
312 		err = tsc2007_probe_properties(&client->dev, ts);
313 	if (err)
314 		return err;
315 
316 	input_dev = devm_input_allocate_device(&client->dev);
317 	if (!input_dev)
318 		return -ENOMEM;
319 
320 	i2c_set_clientdata(client, ts);
321 
322 	ts->client = client;
323 	ts->irq = client->irq;
324 	ts->input = input_dev;
325 
326 	init_waitqueue_head(&ts->wait);
327 	mutex_init(&ts->mlock);
328 
329 	snprintf(ts->phys, sizeof(ts->phys),
330 		 "%s/input0", dev_name(&client->dev));
331 
332 	input_dev->name = "TSC2007 Touchscreen";
333 	input_dev->phys = ts->phys;
334 	input_dev->id.bustype = BUS_I2C;
335 
336 	input_dev->open = tsc2007_open;
337 	input_dev->close = tsc2007_close;
338 
339 	input_set_drvdata(input_dev, ts);
340 
341 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
342 
343 	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzx, 0);
344 	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
345 	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
346 			     ts->fuzzz, 0);
347 
348 	if (pdata) {
349 		if (pdata->exit_platform_hw) {
350 			err = devm_add_action(&client->dev,
351 					      tsc2007_call_exit_platform_hw,
352 					      &client->dev);
353 			if (err) {
354 				dev_err(&client->dev,
355 					"Failed to register exit_platform_hw action, %d\n",
356 					err);
357 				return err;
358 			}
359 		}
360 
361 		if (pdata->init_platform_hw)
362 			pdata->init_platform_hw();
363 	}
364 
365 	err = devm_request_threaded_irq(&client->dev, ts->irq,
366 					NULL, tsc2007_soft_irq,
367 					IRQF_ONESHOT,
368 					client->dev.driver->name, ts);
369 	if (err) {
370 		dev_err(&client->dev, "Failed to request irq %d: %d\n",
371 			ts->irq, err);
372 		return err;
373 	}
374 
375 	tsc2007_stop(ts);
376 
377 	/* power down the chip (TSC2007_SETUP does not ACK on I2C) */
378 	err = tsc2007_xfer(ts, PWRDOWN);
379 	if (err < 0) {
380 		dev_err(&client->dev,
381 			"Failed to setup chip: %d\n", err);
382 		return err;	/* chip does not respond */
383 	}
384 
385 	err = input_register_device(input_dev);
386 	if (err) {
387 		dev_err(&client->dev,
388 			"Failed to register input device: %d\n", err);
389 		return err;
390 	}
391 
392 	err =  tsc2007_iio_configure(ts);
393 	if (err) {
394 		dev_err(&client->dev,
395 			"Failed to register with IIO: %d\n", err);
396 		return err;
397 	}
398 
399 	return 0;
400 }
401 
402 static const struct i2c_device_id tsc2007_idtable[] = {
403 	{ "tsc2007", 0 },
404 	{ }
405 };
406 
407 MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
408 
409 static const struct of_device_id tsc2007_of_match[] = {
410 	{ .compatible = "ti,tsc2007" },
411 	{ /* sentinel */ }
412 };
413 MODULE_DEVICE_TABLE(of, tsc2007_of_match);
414 
415 static struct i2c_driver tsc2007_driver = {
416 	.driver = {
417 		.name	= "tsc2007",
418 		.of_match_table = tsc2007_of_match,
419 	},
420 	.id_table	= tsc2007_idtable,
421 	.probe		= tsc2007_probe,
422 };
423 
424 module_i2c_driver(tsc2007_driver);
425 
426 MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
427 MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
428 MODULE_LICENSE("GPL");
429