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 	spinlock_t		lock;
92 	struct timer_list	penup_timer;
93 
94 	unsigned int		esd_timeout;
95 	struct delayed_work	esd_work;
96 	unsigned long		last_valid_interrupt;
97 
98 	unsigned int		x_plate_ohm;
99 
100 	bool			opened;
101 	bool			suspended;
102 
103 	bool			pen_down;
104 
105 	struct regulator	*vio;
106 
107 	struct gpio_desc	*reset_gpio;
108 	int			(*tsc200x_cmd)(struct device *dev, u8 cmd);
109 	int			irq;
110 };
111 
112 static void tsc200x_update_pen_state(struct tsc200x *ts,
113 				     int x, int y, int pressure)
114 {
115 	if (pressure) {
116 		input_report_abs(ts->idev, ABS_X, x);
117 		input_report_abs(ts->idev, ABS_Y, y);
118 		input_report_abs(ts->idev, ABS_PRESSURE, pressure);
119 		if (!ts->pen_down) {
120 			input_report_key(ts->idev, BTN_TOUCH, !!pressure);
121 			ts->pen_down = true;
122 		}
123 	} else {
124 		input_report_abs(ts->idev, ABS_PRESSURE, 0);
125 		if (ts->pen_down) {
126 			input_report_key(ts->idev, BTN_TOUCH, 0);
127 			ts->pen_down = false;
128 		}
129 	}
130 	input_sync(ts->idev);
131 	dev_dbg(ts->dev, "point(%4d,%4d), pressure (%4d)\n", x, y,
132 		pressure);
133 }
134 
135 static irqreturn_t tsc200x_irq_thread(int irq, void *_ts)
136 {
137 	struct tsc200x *ts = _ts;
138 	unsigned long flags;
139 	unsigned int pressure;
140 	struct tsc200x_data tsdata;
141 	int error;
142 
143 	/* read the coordinates */
144 	error = regmap_bulk_read(ts->regmap, TSC200X_REG_X, &tsdata,
145 				 TSC200X_DATA_REGS);
146 	if (unlikely(error))
147 		goto out;
148 
149 	/* validate position */
150 	if (unlikely(tsdata.x > MAX_12BIT || tsdata.y > MAX_12BIT))
151 		goto out;
152 
153 	/* Skip reading if the pressure components are out of range */
154 	if (unlikely(tsdata.z1 == 0 || tsdata.z2 > MAX_12BIT))
155 		goto out;
156 	if (unlikely(tsdata.z1 >= tsdata.z2))
157 		goto out;
158 
159        /*
160 	* Skip point if this is a pen down with the exact same values as
161 	* the value before pen-up - that implies SPI fed us stale data
162 	*/
163 	if (!ts->pen_down &&
164 	    ts->in_x == tsdata.x && ts->in_y == tsdata.y &&
165 	    ts->in_z1 == tsdata.z1 && ts->in_z2 == tsdata.z2) {
166 		goto out;
167 	}
168 
169 	/*
170 	 * At this point we are happy we have a valid and useful reading.
171 	 * Remember it for later comparisons. We may now begin downsampling.
172 	 */
173 	ts->in_x = tsdata.x;
174 	ts->in_y = tsdata.y;
175 	ts->in_z1 = tsdata.z1;
176 	ts->in_z2 = tsdata.z2;
177 
178 	/* Compute touch pressure resistance using equation #1 */
179 	pressure = tsdata.x * (tsdata.z2 - tsdata.z1) / tsdata.z1;
180 	pressure = pressure * ts->x_plate_ohm / 4096;
181 	if (unlikely(pressure > MAX_12BIT))
182 		goto out;
183 
184 	spin_lock_irqsave(&ts->lock, flags);
185 
186 	tsc200x_update_pen_state(ts, tsdata.x, tsdata.y, pressure);
187 	mod_timer(&ts->penup_timer,
188 		  jiffies + msecs_to_jiffies(TSC200X_PENUP_TIME_MS));
189 
190 	spin_unlock_irqrestore(&ts->lock, flags);
191 
192 	ts->last_valid_interrupt = jiffies;
193 out:
194 	return IRQ_HANDLED;
195 }
196 
197 static void tsc200x_penup_timer(struct timer_list *t)
198 {
199 	struct tsc200x *ts = from_timer(ts, t, penup_timer);
200 	unsigned long flags;
201 
202 	spin_lock_irqsave(&ts->lock, flags);
203 	tsc200x_update_pen_state(ts, 0, 0, 0);
204 	spin_unlock_irqrestore(&ts->lock, flags);
205 }
206 
207 static void tsc200x_start_scan(struct tsc200x *ts)
208 {
209 	regmap_write(ts->regmap, TSC200X_REG_CFR0, TSC200X_CFR0_INITVALUE);
210 	regmap_write(ts->regmap, TSC200X_REG_CFR1, TSC200X_CFR1_INITVALUE);
211 	regmap_write(ts->regmap, TSC200X_REG_CFR2, TSC200X_CFR2_INITVALUE);
212 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_NORMAL);
213 }
214 
215 static void tsc200x_stop_scan(struct tsc200x *ts)
216 {
217 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_STOP);
218 }
219 
220 static void tsc200x_reset(struct tsc200x *ts)
221 {
222 	if (ts->reset_gpio) {
223 		gpiod_set_value_cansleep(ts->reset_gpio, 1);
224 		usleep_range(100, 500); /* only 10us required */
225 		gpiod_set_value_cansleep(ts->reset_gpio, 0);
226 	}
227 }
228 
229 /* must be called with ts->mutex held */
230 static void __tsc200x_disable(struct tsc200x *ts)
231 {
232 	tsc200x_stop_scan(ts);
233 
234 	disable_irq(ts->irq);
235 	del_timer_sync(&ts->penup_timer);
236 
237 	cancel_delayed_work_sync(&ts->esd_work);
238 
239 	enable_irq(ts->irq);
240 }
241 
242 /* must be called with ts->mutex held */
243 static void __tsc200x_enable(struct tsc200x *ts)
244 {
245 	tsc200x_start_scan(ts);
246 
247 	if (ts->esd_timeout && ts->reset_gpio) {
248 		ts->last_valid_interrupt = jiffies;
249 		schedule_delayed_work(&ts->esd_work,
250 				round_jiffies_relative(
251 					msecs_to_jiffies(ts->esd_timeout)));
252 	}
253 }
254 
255 static ssize_t tsc200x_selftest_show(struct device *dev,
256 				     struct device_attribute *attr,
257 				     char *buf)
258 {
259 	struct tsc200x *ts = dev_get_drvdata(dev);
260 	unsigned int temp_high;
261 	unsigned int temp_high_orig;
262 	unsigned int temp_high_test;
263 	bool success = true;
264 	int error;
265 
266 	mutex_lock(&ts->mutex);
267 
268 	/*
269 	 * Test TSC200X communications via temp high register.
270 	 */
271 	__tsc200x_disable(ts);
272 
273 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high_orig);
274 	if (error) {
275 		dev_warn(dev, "selftest failed: read error %d\n", error);
276 		success = false;
277 		goto out;
278 	}
279 
280 	temp_high_test = (temp_high_orig - 1) & MAX_12BIT;
281 
282 	error = regmap_write(ts->regmap, TSC200X_REG_TEMP_HIGH, temp_high_test);
283 	if (error) {
284 		dev_warn(dev, "selftest failed: write error %d\n", error);
285 		success = false;
286 		goto out;
287 	}
288 
289 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
290 	if (error) {
291 		dev_warn(dev, "selftest failed: read error %d after write\n",
292 			 error);
293 		success = false;
294 		goto out;
295 	}
296 
297 	if (temp_high != temp_high_test) {
298 		dev_warn(dev, "selftest failed: %d != %d\n",
299 			 temp_high, temp_high_test);
300 		success = false;
301 	}
302 
303 	/* hardware reset */
304 	tsc200x_reset(ts);
305 
306 	if (!success)
307 		goto out;
308 
309 	/* test that the reset really happened */
310 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
311 	if (error) {
312 		dev_warn(dev, "selftest failed: read error %d after reset\n",
313 			 error);
314 		success = false;
315 		goto out;
316 	}
317 
318 	if (temp_high != temp_high_orig) {
319 		dev_warn(dev, "selftest failed after reset: %d != %d\n",
320 			 temp_high, temp_high_orig);
321 		success = false;
322 	}
323 
324 out:
325 	__tsc200x_enable(ts);
326 	mutex_unlock(&ts->mutex);
327 
328 	return sprintf(buf, "%d\n", success);
329 }
330 
331 static DEVICE_ATTR(selftest, S_IRUGO, tsc200x_selftest_show, NULL);
332 
333 static struct attribute *tsc200x_attrs[] = {
334 	&dev_attr_selftest.attr,
335 	NULL
336 };
337 
338 static umode_t tsc200x_attr_is_visible(struct kobject *kobj,
339 				      struct attribute *attr, int n)
340 {
341 	struct device *dev = container_of(kobj, struct device, kobj);
342 	struct tsc200x *ts = dev_get_drvdata(dev);
343 	umode_t mode = attr->mode;
344 
345 	if (attr == &dev_attr_selftest.attr) {
346 		if (!ts->reset_gpio)
347 			mode = 0;
348 	}
349 
350 	return mode;
351 }
352 
353 static const struct attribute_group tsc200x_attr_group = {
354 	.is_visible	= tsc200x_attr_is_visible,
355 	.attrs		= tsc200x_attrs,
356 };
357 
358 static void tsc200x_esd_work(struct work_struct *work)
359 {
360 	struct tsc200x *ts = container_of(work, struct tsc200x, esd_work.work);
361 	int error;
362 	unsigned int r;
363 
364 	if (!mutex_trylock(&ts->mutex)) {
365 		/*
366 		 * If the mutex is taken, it means that disable or enable is in
367 		 * progress. In that case just reschedule the work. If the work
368 		 * is not needed, it will be canceled by disable.
369 		 */
370 		goto reschedule;
371 	}
372 
373 	if (time_is_after_jiffies(ts->last_valid_interrupt +
374 				  msecs_to_jiffies(ts->esd_timeout)))
375 		goto out;
376 
377 	/* We should be able to read register without disabling interrupts. */
378 	error = regmap_read(ts->regmap, TSC200X_REG_CFR0, &r);
379 	if (!error &&
380 	    !((r ^ TSC200X_CFR0_INITVALUE) & TSC200X_CFR0_RW_MASK)) {
381 		goto out;
382 	}
383 
384 	/*
385 	 * If we could not read our known value from configuration register 0
386 	 * then we should reset the controller as if from power-up and start
387 	 * scanning again.
388 	 */
389 	dev_info(ts->dev, "TSC200X not responding - resetting\n");
390 
391 	disable_irq(ts->irq);
392 	del_timer_sync(&ts->penup_timer);
393 
394 	tsc200x_update_pen_state(ts, 0, 0, 0);
395 
396 	tsc200x_reset(ts);
397 
398 	enable_irq(ts->irq);
399 	tsc200x_start_scan(ts);
400 
401 out:
402 	mutex_unlock(&ts->mutex);
403 reschedule:
404 	/* re-arm the watchdog */
405 	schedule_delayed_work(&ts->esd_work,
406 			      round_jiffies_relative(
407 					msecs_to_jiffies(ts->esd_timeout)));
408 }
409 
410 static int tsc200x_open(struct input_dev *input)
411 {
412 	struct tsc200x *ts = input_get_drvdata(input);
413 
414 	mutex_lock(&ts->mutex);
415 
416 	if (!ts->suspended)
417 		__tsc200x_enable(ts);
418 
419 	ts->opened = true;
420 
421 	mutex_unlock(&ts->mutex);
422 
423 	return 0;
424 }
425 
426 static void tsc200x_close(struct input_dev *input)
427 {
428 	struct tsc200x *ts = input_get_drvdata(input);
429 
430 	mutex_lock(&ts->mutex);
431 
432 	if (!ts->suspended)
433 		__tsc200x_disable(ts);
434 
435 	ts->opened = false;
436 
437 	mutex_unlock(&ts->mutex);
438 }
439 
440 int tsc200x_probe(struct device *dev, int irq, const struct input_id *tsc_id,
441 		  struct regmap *regmap,
442 		  int (*tsc200x_cmd)(struct device *dev, u8 cmd))
443 {
444 	struct tsc200x *ts;
445 	struct input_dev *input_dev;
446 	u32 x_plate_ohm;
447 	u32 esd_timeout;
448 	int error;
449 
450 	if (irq <= 0) {
451 		dev_err(dev, "no irq\n");
452 		return -ENODEV;
453 	}
454 
455 	if (IS_ERR(regmap))
456 		return PTR_ERR(regmap);
457 
458 	if (!tsc200x_cmd) {
459 		dev_err(dev, "no cmd function\n");
460 		return -ENODEV;
461 	}
462 
463 	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
464 	if (!ts)
465 		return -ENOMEM;
466 
467 	input_dev = devm_input_allocate_device(dev);
468 	if (!input_dev)
469 		return -ENOMEM;
470 
471 	ts->irq = irq;
472 	ts->dev = dev;
473 	ts->idev = input_dev;
474 	ts->regmap = regmap;
475 	ts->tsc200x_cmd = tsc200x_cmd;
476 
477 	error = device_property_read_u32(dev, "ti,x-plate-ohms", &x_plate_ohm);
478 	ts->x_plate_ohm = error ? TSC200X_DEF_RESISTOR : x_plate_ohm;
479 
480 	error = device_property_read_u32(dev, "ti,esd-recovery-timeout-ms",
481 					 &esd_timeout);
482 	ts->esd_timeout = error ? 0 : esd_timeout;
483 
484 	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
485 	if (IS_ERR(ts->reset_gpio)) {
486 		error = PTR_ERR(ts->reset_gpio);
487 		dev_err(dev, "error acquiring reset gpio: %d\n", error);
488 		return error;
489 	}
490 
491 	ts->vio = devm_regulator_get(dev, "vio");
492 	if (IS_ERR(ts->vio)) {
493 		error = PTR_ERR(ts->vio);
494 		dev_err(dev, "error acquiring vio regulator: %d", error);
495 		return error;
496 	}
497 
498 	mutex_init(&ts->mutex);
499 
500 	spin_lock_init(&ts->lock);
501 	timer_setup(&ts->penup_timer, tsc200x_penup_timer, 0);
502 
503 	INIT_DELAYED_WORK(&ts->esd_work, tsc200x_esd_work);
504 
505 	snprintf(ts->phys, sizeof(ts->phys),
506 		 "%s/input-ts", dev_name(dev));
507 
508 	if (tsc_id->product == 2004) {
509 		input_dev->name = "TSC200X touchscreen";
510 	} else {
511 		input_dev->name = devm_kasprintf(dev, GFP_KERNEL,
512 						 "TSC%04d touchscreen",
513 						 tsc_id->product);
514 		if (!input_dev->name)
515 			return -ENOMEM;
516 	}
517 
518 	input_dev->phys = ts->phys;
519 	input_dev->id = *tsc_id;
520 
521 	input_dev->open = tsc200x_open;
522 	input_dev->close = tsc200x_close;
523 
524 	input_set_drvdata(input_dev, ts);
525 
526 	__set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
527 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
528 
529 	input_set_abs_params(input_dev, ABS_X,
530 			     0, MAX_12BIT, TSC200X_DEF_X_FUZZ, 0);
531 	input_set_abs_params(input_dev, ABS_Y,
532 			     0, MAX_12BIT, TSC200X_DEF_Y_FUZZ, 0);
533 	input_set_abs_params(input_dev, ABS_PRESSURE,
534 			     0, MAX_12BIT, TSC200X_DEF_P_FUZZ, 0);
535 
536 	touchscreen_parse_properties(input_dev, false, NULL);
537 
538 	/* Ensure the touchscreen is off */
539 	tsc200x_stop_scan(ts);
540 
541 	error = devm_request_threaded_irq(dev, irq, NULL,
542 					  tsc200x_irq_thread,
543 					  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
544 					  "tsc200x", ts);
545 	if (error) {
546 		dev_err(dev, "Failed to request irq, err: %d\n", error);
547 		return error;
548 	}
549 
550 	error = regulator_enable(ts->vio);
551 	if (error)
552 		return error;
553 
554 	dev_set_drvdata(dev, ts);
555 	error = sysfs_create_group(&dev->kobj, &tsc200x_attr_group);
556 	if (error) {
557 		dev_err(dev,
558 			"Failed to create sysfs attributes, err: %d\n", error);
559 		goto disable_regulator;
560 	}
561 
562 	error = input_register_device(ts->idev);
563 	if (error) {
564 		dev_err(dev,
565 			"Failed to register input device, err: %d\n", error);
566 		goto err_remove_sysfs;
567 	}
568 
569 	irq_set_irq_wake(irq, 1);
570 	return 0;
571 
572 err_remove_sysfs:
573 	sysfs_remove_group(&dev->kobj, &tsc200x_attr_group);
574 disable_regulator:
575 	regulator_disable(ts->vio);
576 	return error;
577 }
578 EXPORT_SYMBOL_GPL(tsc200x_probe);
579 
580 int tsc200x_remove(struct device *dev)
581 {
582 	struct tsc200x *ts = dev_get_drvdata(dev);
583 
584 	sysfs_remove_group(&dev->kobj, &tsc200x_attr_group);
585 
586 	regulator_disable(ts->vio);
587 
588 	return 0;
589 }
590 EXPORT_SYMBOL_GPL(tsc200x_remove);
591 
592 static int __maybe_unused tsc200x_suspend(struct device *dev)
593 {
594 	struct tsc200x *ts = dev_get_drvdata(dev);
595 
596 	mutex_lock(&ts->mutex);
597 
598 	if (!ts->suspended && ts->opened)
599 		__tsc200x_disable(ts);
600 
601 	ts->suspended = true;
602 
603 	mutex_unlock(&ts->mutex);
604 
605 	return 0;
606 }
607 
608 static int __maybe_unused tsc200x_resume(struct device *dev)
609 {
610 	struct tsc200x *ts = dev_get_drvdata(dev);
611 
612 	mutex_lock(&ts->mutex);
613 
614 	if (ts->suspended && ts->opened)
615 		__tsc200x_enable(ts);
616 
617 	ts->suspended = false;
618 
619 	mutex_unlock(&ts->mutex);
620 
621 	return 0;
622 }
623 
624 SIMPLE_DEV_PM_OPS(tsc200x_pm_ops, tsc200x_suspend, tsc200x_resume);
625 EXPORT_SYMBOL_GPL(tsc200x_pm_ops);
626 
627 MODULE_AUTHOR("Lauri Leukkunen <lauri.leukkunen@nokia.com>");
628 MODULE_DESCRIPTION("TSC200x Touchscreen Driver Core");
629 MODULE_LICENSE("GPL");
630