xref: /linux/drivers/input/touchscreen/tsc200x-core.c (revision 3bf3e21c15d4386a5f15118ec39bbc1b67ea5759) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * TSC2004/TSC2005 touchscreen driver core
4  *
5  * Copyright (C) 2006-2010 Nokia Corporation
6  * Copyright (C) 2015 QWERTY Embedded Design
7  * Copyright (C) 2015 EMAC Inc.
8  *
9  * Author: Lauri Leukkunen <lauri.leukkunen@nokia.com>
10  * based on TSC2301 driver by Klaus K. Pedersen <klaus.k.pedersen@nokia.com>
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/input.h>
16 #include <linux/input/touchscreen.h>
17 #include <linux/interrupt.h>
18 #include <linux/delay.h>
19 #include <linux/pm.h>
20 #include <linux/of.h>
21 #include <linux/regulator/consumer.h>
22 #include <linux/regmap.h>
23 #include <linux/gpio/consumer.h>
24 #include "tsc200x-core.h"
25 
26 /*
27  * The touchscreen interface operates as follows:
28  *
29  * 1) Pen is pressed against the touchscreen.
30  * 2) TSC200X performs AD conversion.
31  * 3) After the conversion is done TSC200X drives DAV line down.
32  * 4) GPIO IRQ is received and tsc200x_irq_thread() is scheduled.
33  * 5) tsc200x_irq_thread() queues up a transfer to fetch the x, y, z1, z2
34  *    values.
35  * 6) tsc200x_irq_thread() reports coordinates to input layer and sets up
36  *    tsc200x_penup_timer() to be called after TSC200X_PENUP_TIME_MS (40ms).
37  * 7) When the penup timer expires, there have not been touch or DAV interrupts
38  *    during the last 40ms which means the pen has been lifted.
39  *
40  * ESD recovery via a hardware reset is done if the TSC200X doesn't respond
41  * after a configurable period (in ms) of activity. If esd_timeout is 0, the
42  * watchdog is disabled.
43  */
44 
45 static const struct regmap_range tsc200x_writable_ranges[] = {
46 	regmap_reg_range(TSC200X_REG_AUX_HIGH, TSC200X_REG_CFR2),
47 };
48 
49 static const struct regmap_access_table tsc200x_writable_table = {
50 	.yes_ranges = tsc200x_writable_ranges,
51 	.n_yes_ranges = ARRAY_SIZE(tsc200x_writable_ranges),
52 };
53 
54 const struct regmap_config tsc200x_regmap_config = {
55 	.reg_bits = 8,
56 	.val_bits = 16,
57 	.reg_stride = 0x08,
58 	.max_register = 0x78,
59 	.read_flag_mask = TSC200X_REG_READ,
60 	.write_flag_mask = TSC200X_REG_PND0,
61 	.wr_table = &tsc200x_writable_table,
62 	.use_single_read = true,
63 	.use_single_write = true,
64 };
65 EXPORT_SYMBOL_GPL(tsc200x_regmap_config);
66 
67 struct tsc200x_data {
68 	u16 x;
69 	u16 y;
70 	u16 z1;
71 	u16 z2;
72 } __packed;
73 #define TSC200X_DATA_REGS 4
74 
75 struct tsc200x {
76 	struct device           *dev;
77 	struct regmap		*regmap;
78 	__u16                   bustype;
79 
80 	struct input_dev	*idev;
81 	char			phys[32];
82 
83 	struct mutex		mutex;
84 
85 	/* raw copy of previous x,y,z */
86 	int			in_x;
87 	int			in_y;
88 	int                     in_z1;
89 	int			in_z2;
90 
91 	struct touchscreen_properties prop;
92 
93 	spinlock_t		lock;
94 	struct timer_list	penup_timer;
95 
96 	unsigned int		esd_timeout;
97 	struct delayed_work	esd_work;
98 	unsigned long		last_valid_interrupt;
99 
100 	unsigned int		x_plate_ohm;
101 
102 	bool			opened;
103 	bool			suspended;
104 
105 	bool			pen_down;
106 
107 	struct regulator	*vio;
108 
109 	struct gpio_desc	*reset_gpio;
110 	int			(*tsc200x_cmd)(struct device *dev, u8 cmd);
111 	int			irq;
112 };
113 
114 static void tsc200x_update_pen_state(struct tsc200x *ts,
115 				     int x, int y, int pressure)
116 {
117 	if (pressure) {
118 		touchscreen_report_pos(ts->idev, &ts->prop, x, y, false);
119 		input_report_abs(ts->idev, ABS_PRESSURE, pressure);
120 		if (!ts->pen_down) {
121 			input_report_key(ts->idev, BTN_TOUCH, !!pressure);
122 			ts->pen_down = true;
123 		}
124 	} else {
125 		input_report_abs(ts->idev, ABS_PRESSURE, 0);
126 		if (ts->pen_down) {
127 			input_report_key(ts->idev, BTN_TOUCH, 0);
128 			ts->pen_down = false;
129 		}
130 	}
131 	input_sync(ts->idev);
132 	dev_dbg(ts->dev, "point(%4d,%4d), pressure (%4d)\n", x, y,
133 		pressure);
134 }
135 
136 static irqreturn_t tsc200x_irq_thread(int irq, void *_ts)
137 {
138 	struct tsc200x *ts = _ts;
139 	unsigned long flags;
140 	unsigned int pressure;
141 	struct tsc200x_data tsdata;
142 	int error;
143 
144 	/* read the coordinates */
145 	error = regmap_bulk_read(ts->regmap, TSC200X_REG_X, &tsdata,
146 				 TSC200X_DATA_REGS);
147 	if (unlikely(error))
148 		goto out;
149 
150 	/* validate position */
151 	if (unlikely(tsdata.x > MAX_12BIT || tsdata.y > MAX_12BIT))
152 		goto out;
153 
154 	/* Skip reading if the pressure components are out of range */
155 	if (unlikely(tsdata.z1 == 0 || tsdata.z2 > MAX_12BIT))
156 		goto out;
157 	if (unlikely(tsdata.z1 >= tsdata.z2))
158 		goto out;
159 
160        /*
161 	* Skip point if this is a pen down with the exact same values as
162 	* the value before pen-up - that implies SPI fed us stale data
163 	*/
164 	if (!ts->pen_down &&
165 	    ts->in_x == tsdata.x && ts->in_y == tsdata.y &&
166 	    ts->in_z1 == tsdata.z1 && ts->in_z2 == tsdata.z2) {
167 		goto out;
168 	}
169 
170 	/*
171 	 * At this point we are happy we have a valid and useful reading.
172 	 * Remember it for later comparisons. We may now begin downsampling.
173 	 */
174 	ts->in_x = tsdata.x;
175 	ts->in_y = tsdata.y;
176 	ts->in_z1 = tsdata.z1;
177 	ts->in_z2 = tsdata.z2;
178 
179 	/* Compute touch pressure resistance using equation #1 */
180 	pressure = tsdata.x * (tsdata.z2 - tsdata.z1) / tsdata.z1;
181 	pressure = pressure * ts->x_plate_ohm / 4096;
182 	if (unlikely(pressure > MAX_12BIT))
183 		goto out;
184 
185 	spin_lock_irqsave(&ts->lock, flags);
186 
187 	tsc200x_update_pen_state(ts, tsdata.x, tsdata.y, pressure);
188 	mod_timer(&ts->penup_timer,
189 		  jiffies + msecs_to_jiffies(TSC200X_PENUP_TIME_MS));
190 
191 	spin_unlock_irqrestore(&ts->lock, flags);
192 
193 	ts->last_valid_interrupt = jiffies;
194 out:
195 	return IRQ_HANDLED;
196 }
197 
198 static void tsc200x_penup_timer(struct timer_list *t)
199 {
200 	struct tsc200x *ts = from_timer(ts, t, penup_timer);
201 	unsigned long flags;
202 
203 	spin_lock_irqsave(&ts->lock, flags);
204 	tsc200x_update_pen_state(ts, 0, 0, 0);
205 	spin_unlock_irqrestore(&ts->lock, flags);
206 }
207 
208 static void tsc200x_start_scan(struct tsc200x *ts)
209 {
210 	regmap_write(ts->regmap, TSC200X_REG_CFR0, TSC200X_CFR0_INITVALUE);
211 	regmap_write(ts->regmap, TSC200X_REG_CFR1, TSC200X_CFR1_INITVALUE);
212 	regmap_write(ts->regmap, TSC200X_REG_CFR2, TSC200X_CFR2_INITVALUE);
213 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_NORMAL);
214 }
215 
216 static void tsc200x_stop_scan(struct tsc200x *ts)
217 {
218 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_STOP);
219 }
220 
221 static void tsc200x_reset(struct tsc200x *ts)
222 {
223 	if (ts->reset_gpio) {
224 		gpiod_set_value_cansleep(ts->reset_gpio, 1);
225 		usleep_range(100, 500); /* only 10us required */
226 		gpiod_set_value_cansleep(ts->reset_gpio, 0);
227 	}
228 }
229 
230 /* must be called with ts->mutex held */
231 static void __tsc200x_disable(struct tsc200x *ts)
232 {
233 	tsc200x_stop_scan(ts);
234 
235 	disable_irq(ts->irq);
236 	del_timer_sync(&ts->penup_timer);
237 
238 	cancel_delayed_work_sync(&ts->esd_work);
239 
240 	enable_irq(ts->irq);
241 }
242 
243 /* must be called with ts->mutex held */
244 static void __tsc200x_enable(struct tsc200x *ts)
245 {
246 	tsc200x_start_scan(ts);
247 
248 	if (ts->esd_timeout && ts->reset_gpio) {
249 		ts->last_valid_interrupt = jiffies;
250 		schedule_delayed_work(&ts->esd_work,
251 				round_jiffies_relative(
252 					msecs_to_jiffies(ts->esd_timeout)));
253 	}
254 }
255 
256 static ssize_t tsc200x_selftest_show(struct device *dev,
257 				     struct device_attribute *attr,
258 				     char *buf)
259 {
260 	struct tsc200x *ts = dev_get_drvdata(dev);
261 	unsigned int temp_high;
262 	unsigned int temp_high_orig;
263 	unsigned int temp_high_test;
264 	bool success = true;
265 	int error;
266 
267 	mutex_lock(&ts->mutex);
268 
269 	/*
270 	 * Test TSC200X communications via temp high register.
271 	 */
272 	__tsc200x_disable(ts);
273 
274 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high_orig);
275 	if (error) {
276 		dev_warn(dev, "selftest failed: read error %d\n", error);
277 		success = false;
278 		goto out;
279 	}
280 
281 	temp_high_test = (temp_high_orig - 1) & MAX_12BIT;
282 
283 	error = regmap_write(ts->regmap, TSC200X_REG_TEMP_HIGH, temp_high_test);
284 	if (error) {
285 		dev_warn(dev, "selftest failed: write error %d\n", error);
286 		success = false;
287 		goto out;
288 	}
289 
290 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
291 	if (error) {
292 		dev_warn(dev, "selftest failed: read error %d after write\n",
293 			 error);
294 		success = false;
295 		goto out;
296 	}
297 
298 	if (temp_high != temp_high_test) {
299 		dev_warn(dev, "selftest failed: %d != %d\n",
300 			 temp_high, temp_high_test);
301 		success = false;
302 	}
303 
304 	/* hardware reset */
305 	tsc200x_reset(ts);
306 
307 	if (!success)
308 		goto out;
309 
310 	/* test that the reset really happened */
311 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
312 	if (error) {
313 		dev_warn(dev, "selftest failed: read error %d after reset\n",
314 			 error);
315 		success = false;
316 		goto out;
317 	}
318 
319 	if (temp_high != temp_high_orig) {
320 		dev_warn(dev, "selftest failed after reset: %d != %d\n",
321 			 temp_high, temp_high_orig);
322 		success = false;
323 	}
324 
325 out:
326 	__tsc200x_enable(ts);
327 	mutex_unlock(&ts->mutex);
328 
329 	return sprintf(buf, "%d\n", success);
330 }
331 
332 static DEVICE_ATTR(selftest, S_IRUGO, tsc200x_selftest_show, NULL);
333 
334 static struct attribute *tsc200x_attrs[] = {
335 	&dev_attr_selftest.attr,
336 	NULL
337 };
338 
339 static umode_t tsc200x_attr_is_visible(struct kobject *kobj,
340 				      struct attribute *attr, int n)
341 {
342 	struct device *dev = kobj_to_dev(kobj);
343 	struct tsc200x *ts = dev_get_drvdata(dev);
344 	umode_t mode = attr->mode;
345 
346 	if (attr == &dev_attr_selftest.attr) {
347 		if (!ts->reset_gpio)
348 			mode = 0;
349 	}
350 
351 	return mode;
352 }
353 
354 static const struct attribute_group tsc200x_attr_group = {
355 	.is_visible	= tsc200x_attr_is_visible,
356 	.attrs		= tsc200x_attrs,
357 };
358 
359 const struct attribute_group *tsc200x_groups[] = {
360 	&tsc200x_attr_group,
361 	NULL
362 };
363 EXPORT_SYMBOL_GPL(tsc200x_groups);
364 
365 static void tsc200x_esd_work(struct work_struct *work)
366 {
367 	struct tsc200x *ts = container_of(work, struct tsc200x, esd_work.work);
368 	int error;
369 	unsigned int r;
370 
371 	if (!mutex_trylock(&ts->mutex)) {
372 		/*
373 		 * If the mutex is taken, it means that disable or enable is in
374 		 * progress. In that case just reschedule the work. If the work
375 		 * is not needed, it will be canceled by disable.
376 		 */
377 		goto reschedule;
378 	}
379 
380 	if (time_is_after_jiffies(ts->last_valid_interrupt +
381 				  msecs_to_jiffies(ts->esd_timeout)))
382 		goto out;
383 
384 	/* We should be able to read register without disabling interrupts. */
385 	error = regmap_read(ts->regmap, TSC200X_REG_CFR0, &r);
386 	if (!error &&
387 	    !((r ^ TSC200X_CFR0_INITVALUE) & TSC200X_CFR0_RW_MASK)) {
388 		goto out;
389 	}
390 
391 	/*
392 	 * If we could not read our known value from configuration register 0
393 	 * then we should reset the controller as if from power-up and start
394 	 * scanning again.
395 	 */
396 	dev_info(ts->dev, "TSC200X not responding - resetting\n");
397 
398 	disable_irq(ts->irq);
399 	del_timer_sync(&ts->penup_timer);
400 
401 	tsc200x_update_pen_state(ts, 0, 0, 0);
402 
403 	tsc200x_reset(ts);
404 
405 	enable_irq(ts->irq);
406 	tsc200x_start_scan(ts);
407 
408 out:
409 	mutex_unlock(&ts->mutex);
410 reschedule:
411 	/* re-arm the watchdog */
412 	schedule_delayed_work(&ts->esd_work,
413 			      round_jiffies_relative(
414 					msecs_to_jiffies(ts->esd_timeout)));
415 }
416 
417 static int tsc200x_open(struct input_dev *input)
418 {
419 	struct tsc200x *ts = input_get_drvdata(input);
420 
421 	mutex_lock(&ts->mutex);
422 
423 	if (!ts->suspended)
424 		__tsc200x_enable(ts);
425 
426 	ts->opened = true;
427 
428 	mutex_unlock(&ts->mutex);
429 
430 	return 0;
431 }
432 
433 static void tsc200x_close(struct input_dev *input)
434 {
435 	struct tsc200x *ts = input_get_drvdata(input);
436 
437 	mutex_lock(&ts->mutex);
438 
439 	if (!ts->suspended)
440 		__tsc200x_disable(ts);
441 
442 	ts->opened = false;
443 
444 	mutex_unlock(&ts->mutex);
445 }
446 
447 int tsc200x_probe(struct device *dev, int irq, const struct input_id *tsc_id,
448 		  struct regmap *regmap,
449 		  int (*tsc200x_cmd)(struct device *dev, u8 cmd))
450 {
451 	struct tsc200x *ts;
452 	struct input_dev *input_dev;
453 	u32 x_plate_ohm;
454 	u32 esd_timeout;
455 	int error;
456 
457 	if (irq <= 0) {
458 		dev_err(dev, "no irq\n");
459 		return -ENODEV;
460 	}
461 
462 	if (IS_ERR(regmap))
463 		return PTR_ERR(regmap);
464 
465 	if (!tsc200x_cmd) {
466 		dev_err(dev, "no cmd function\n");
467 		return -ENODEV;
468 	}
469 
470 	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
471 	if (!ts)
472 		return -ENOMEM;
473 
474 	input_dev = devm_input_allocate_device(dev);
475 	if (!input_dev)
476 		return -ENOMEM;
477 
478 	ts->irq = irq;
479 	ts->dev = dev;
480 	ts->idev = input_dev;
481 	ts->regmap = regmap;
482 	ts->tsc200x_cmd = tsc200x_cmd;
483 
484 	error = device_property_read_u32(dev, "ti,x-plate-ohms", &x_plate_ohm);
485 	ts->x_plate_ohm = error ? TSC200X_DEF_RESISTOR : x_plate_ohm;
486 
487 	error = device_property_read_u32(dev, "ti,esd-recovery-timeout-ms",
488 					 &esd_timeout);
489 	ts->esd_timeout = error ? 0 : esd_timeout;
490 
491 	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
492 	if (IS_ERR(ts->reset_gpio)) {
493 		error = PTR_ERR(ts->reset_gpio);
494 		dev_err(dev, "error acquiring reset gpio: %d\n", error);
495 		return error;
496 	}
497 
498 	ts->vio = devm_regulator_get(dev, "vio");
499 	if (IS_ERR(ts->vio)) {
500 		error = PTR_ERR(ts->vio);
501 		dev_err(dev, "error acquiring vio regulator: %d", error);
502 		return error;
503 	}
504 
505 	mutex_init(&ts->mutex);
506 
507 	spin_lock_init(&ts->lock);
508 	timer_setup(&ts->penup_timer, tsc200x_penup_timer, 0);
509 
510 	INIT_DELAYED_WORK(&ts->esd_work, tsc200x_esd_work);
511 
512 	snprintf(ts->phys, sizeof(ts->phys),
513 		 "%s/input-ts", dev_name(dev));
514 
515 	if (tsc_id->product == 2004) {
516 		input_dev->name = "TSC200X touchscreen";
517 	} else {
518 		input_dev->name = devm_kasprintf(dev, GFP_KERNEL,
519 						 "TSC%04d touchscreen",
520 						 tsc_id->product);
521 		if (!input_dev->name)
522 			return -ENOMEM;
523 	}
524 
525 	input_dev->phys = ts->phys;
526 	input_dev->id = *tsc_id;
527 
528 	input_dev->open = tsc200x_open;
529 	input_dev->close = tsc200x_close;
530 
531 	input_set_drvdata(input_dev, ts);
532 
533 	__set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
534 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
535 
536 	input_set_abs_params(input_dev, ABS_X,
537 			     0, MAX_12BIT, TSC200X_DEF_X_FUZZ, 0);
538 	input_set_abs_params(input_dev, ABS_Y,
539 			     0, MAX_12BIT, TSC200X_DEF_Y_FUZZ, 0);
540 	input_set_abs_params(input_dev, ABS_PRESSURE,
541 			     0, MAX_12BIT, TSC200X_DEF_P_FUZZ, 0);
542 
543 	touchscreen_parse_properties(input_dev, false, &ts->prop);
544 
545 	/* Ensure the touchscreen is off */
546 	tsc200x_stop_scan(ts);
547 
548 	error = devm_request_threaded_irq(dev, irq, NULL,
549 					  tsc200x_irq_thread,
550 					  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
551 					  "tsc200x", ts);
552 	if (error) {
553 		dev_err(dev, "Failed to request irq, err: %d\n", error);
554 		return error;
555 	}
556 
557 	error = regulator_enable(ts->vio);
558 	if (error)
559 		return error;
560 
561 	dev_set_drvdata(dev, ts);
562 
563 	error = input_register_device(ts->idev);
564 	if (error) {
565 		dev_err(dev,
566 			"Failed to register input device, err: %d\n", error);
567 		goto disable_regulator;
568 	}
569 
570 	irq_set_irq_wake(irq, 1);
571 	return 0;
572 
573 disable_regulator:
574 	regulator_disable(ts->vio);
575 	return error;
576 }
577 EXPORT_SYMBOL_GPL(tsc200x_probe);
578 
579 void tsc200x_remove(struct device *dev)
580 {
581 	struct tsc200x *ts = dev_get_drvdata(dev);
582 
583 	regulator_disable(ts->vio);
584 }
585 EXPORT_SYMBOL_GPL(tsc200x_remove);
586 
587 static int tsc200x_suspend(struct device *dev)
588 {
589 	struct tsc200x *ts = dev_get_drvdata(dev);
590 
591 	mutex_lock(&ts->mutex);
592 
593 	if (!ts->suspended && ts->opened)
594 		__tsc200x_disable(ts);
595 
596 	ts->suspended = true;
597 
598 	mutex_unlock(&ts->mutex);
599 
600 	return 0;
601 }
602 
603 static int tsc200x_resume(struct device *dev)
604 {
605 	struct tsc200x *ts = dev_get_drvdata(dev);
606 
607 	mutex_lock(&ts->mutex);
608 
609 	if (ts->suspended && ts->opened)
610 		__tsc200x_enable(ts);
611 
612 	ts->suspended = false;
613 
614 	mutex_unlock(&ts->mutex);
615 
616 	return 0;
617 }
618 
619 EXPORT_GPL_SIMPLE_DEV_PM_OPS(tsc200x_pm_ops, tsc200x_suspend, tsc200x_resume);
620 
621 MODULE_AUTHOR("Lauri Leukkunen <lauri.leukkunen@nokia.com>");
622 MODULE_DESCRIPTION("TSC200x Touchscreen Driver Core");
623 MODULE_LICENSE("GPL");
624