1 /*
2  * TSC2004/TSC2005 touchscreen driver core
3  *
4  * Copyright (C) 2006-2010 Nokia Corporation
5  * Copyright (C) 2015 QWERTY Embedded Design
6  * Copyright (C) 2015 EMAC Inc.
7  *
8  * Author: Lauri Leukkunen <lauri.leukkunen@nokia.com>
9  * based on TSC2301 driver by Klaus K. Pedersen <klaus.k.pedersen@nokia.com>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU General Public License for more details.
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/input.h>
25 #include <linux/input/touchscreen.h>
26 #include <linux/interrupt.h>
27 #include <linux/delay.h>
28 #include <linux/pm.h>
29 #include <linux/of.h>
30 #include <linux/regulator/consumer.h>
31 #include <linux/regmap.h>
32 #include <linux/gpio/consumer.h>
33 #include "tsc200x-core.h"
34 
35 /*
36  * The touchscreen interface operates as follows:
37  *
38  * 1) Pen is pressed against the touchscreen.
39  * 2) TSC200X performs AD conversion.
40  * 3) After the conversion is done TSC200X drives DAV line down.
41  * 4) GPIO IRQ is received and tsc200x_irq_thread() is scheduled.
42  * 5) tsc200x_irq_thread() queues up a transfer to fetch the x, y, z1, z2
43  *    values.
44  * 6) tsc200x_irq_thread() reports coordinates to input layer and sets up
45  *    tsc200x_penup_timer() to be called after TSC200X_PENUP_TIME_MS (40ms).
46  * 7) When the penup timer expires, there have not been touch or DAV interrupts
47  *    during the last 40ms which means the pen has been lifted.
48  *
49  * ESD recovery via a hardware reset is done if the TSC200X doesn't respond
50  * after a configurable period (in ms) of activity. If esd_timeout is 0, the
51  * watchdog is disabled.
52  */
53 
54 static const struct regmap_range tsc200x_writable_ranges[] = {
55 	regmap_reg_range(TSC200X_REG_AUX_HIGH, TSC200X_REG_CFR2),
56 };
57 
58 static const struct regmap_access_table tsc200x_writable_table = {
59 	.yes_ranges = tsc200x_writable_ranges,
60 	.n_yes_ranges = ARRAY_SIZE(tsc200x_writable_ranges),
61 };
62 
63 const struct regmap_config tsc200x_regmap_config = {
64 	.reg_bits = 8,
65 	.val_bits = 16,
66 	.reg_stride = 0x08,
67 	.max_register = 0x78,
68 	.read_flag_mask = TSC200X_REG_READ,
69 	.write_flag_mask = TSC200X_REG_PND0,
70 	.wr_table = &tsc200x_writable_table,
71 	.use_single_rw = true,
72 };
73 EXPORT_SYMBOL_GPL(tsc200x_regmap_config);
74 
75 struct tsc200x_data {
76 	u16 x;
77 	u16 y;
78 	u16 z1;
79 	u16 z2;
80 } __packed;
81 #define TSC200X_DATA_REGS 4
82 
83 struct tsc200x {
84 	struct device           *dev;
85 	struct regmap		*regmap;
86 	__u16                   bustype;
87 
88 	struct input_dev	*idev;
89 	char			phys[32];
90 
91 	struct mutex		mutex;
92 
93 	/* raw copy of previous x,y,z */
94 	int			in_x;
95 	int			in_y;
96 	int                     in_z1;
97 	int			in_z2;
98 
99 	spinlock_t		lock;
100 	struct timer_list	penup_timer;
101 
102 	unsigned int		esd_timeout;
103 	struct delayed_work	esd_work;
104 	unsigned long		last_valid_interrupt;
105 
106 	unsigned int		x_plate_ohm;
107 
108 	bool			opened;
109 	bool			suspended;
110 
111 	bool			pen_down;
112 
113 	struct regulator	*vio;
114 
115 	struct gpio_desc	*reset_gpio;
116 	int			(*tsc200x_cmd)(struct device *dev, u8 cmd);
117 	int			irq;
118 };
119 
120 static void tsc200x_update_pen_state(struct tsc200x *ts,
121 				     int x, int y, int pressure)
122 {
123 	if (pressure) {
124 		input_report_abs(ts->idev, ABS_X, x);
125 		input_report_abs(ts->idev, ABS_Y, y);
126 		input_report_abs(ts->idev, ABS_PRESSURE, pressure);
127 		if (!ts->pen_down) {
128 			input_report_key(ts->idev, BTN_TOUCH, !!pressure);
129 			ts->pen_down = true;
130 		}
131 	} else {
132 		input_report_abs(ts->idev, ABS_PRESSURE, 0);
133 		if (ts->pen_down) {
134 			input_report_key(ts->idev, BTN_TOUCH, 0);
135 			ts->pen_down = false;
136 		}
137 	}
138 	input_sync(ts->idev);
139 	dev_dbg(ts->dev, "point(%4d,%4d), pressure (%4d)\n", x, y,
140 		pressure);
141 }
142 
143 static irqreturn_t tsc200x_irq_thread(int irq, void *_ts)
144 {
145 	struct tsc200x *ts = _ts;
146 	unsigned long flags;
147 	unsigned int pressure;
148 	struct tsc200x_data tsdata;
149 	int error;
150 
151 	/* read the coordinates */
152 	error = regmap_bulk_read(ts->regmap, TSC200X_REG_X, &tsdata,
153 				 TSC200X_DATA_REGS);
154 	if (unlikely(error))
155 		goto out;
156 
157 	/* validate position */
158 	if (unlikely(tsdata.x > MAX_12BIT || tsdata.y > MAX_12BIT))
159 		goto out;
160 
161 	/* Skip reading if the pressure components are out of range */
162 	if (unlikely(tsdata.z1 == 0 || tsdata.z2 > MAX_12BIT))
163 		goto out;
164 	if (unlikely(tsdata.z1 >= tsdata.z2))
165 		goto out;
166 
167        /*
168 	* Skip point if this is a pen down with the exact same values as
169 	* the value before pen-up - that implies SPI fed us stale data
170 	*/
171 	if (!ts->pen_down &&
172 	    ts->in_x == tsdata.x && ts->in_y == tsdata.y &&
173 	    ts->in_z1 == tsdata.z1 && ts->in_z2 == tsdata.z2) {
174 		goto out;
175 	}
176 
177 	/*
178 	 * At this point we are happy we have a valid and useful reading.
179 	 * Remember it for later comparisons. We may now begin downsampling.
180 	 */
181 	ts->in_x = tsdata.x;
182 	ts->in_y = tsdata.y;
183 	ts->in_z1 = tsdata.z1;
184 	ts->in_z2 = tsdata.z2;
185 
186 	/* Compute touch pressure resistance using equation #1 */
187 	pressure = tsdata.x * (tsdata.z2 - tsdata.z1) / tsdata.z1;
188 	pressure = pressure * ts->x_plate_ohm / 4096;
189 	if (unlikely(pressure > MAX_12BIT))
190 		goto out;
191 
192 	spin_lock_irqsave(&ts->lock, flags);
193 
194 	tsc200x_update_pen_state(ts, tsdata.x, tsdata.y, pressure);
195 	mod_timer(&ts->penup_timer,
196 		  jiffies + msecs_to_jiffies(TSC200X_PENUP_TIME_MS));
197 
198 	spin_unlock_irqrestore(&ts->lock, flags);
199 
200 	ts->last_valid_interrupt = jiffies;
201 out:
202 	return IRQ_HANDLED;
203 }
204 
205 static void tsc200x_penup_timer(struct timer_list *t)
206 {
207 	struct tsc200x *ts = from_timer(ts, t, penup_timer);
208 	unsigned long flags;
209 
210 	spin_lock_irqsave(&ts->lock, flags);
211 	tsc200x_update_pen_state(ts, 0, 0, 0);
212 	spin_unlock_irqrestore(&ts->lock, flags);
213 }
214 
215 static void tsc200x_start_scan(struct tsc200x *ts)
216 {
217 	regmap_write(ts->regmap, TSC200X_REG_CFR0, TSC200X_CFR0_INITVALUE);
218 	regmap_write(ts->regmap, TSC200X_REG_CFR1, TSC200X_CFR1_INITVALUE);
219 	regmap_write(ts->regmap, TSC200X_REG_CFR2, TSC200X_CFR2_INITVALUE);
220 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_NORMAL);
221 }
222 
223 static void tsc200x_stop_scan(struct tsc200x *ts)
224 {
225 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_STOP);
226 }
227 
228 static void tsc200x_reset(struct tsc200x *ts)
229 {
230 	if (ts->reset_gpio) {
231 		gpiod_set_value_cansleep(ts->reset_gpio, 1);
232 		usleep_range(100, 500); /* only 10us required */
233 		gpiod_set_value_cansleep(ts->reset_gpio, 0);
234 	}
235 }
236 
237 /* must be called with ts->mutex held */
238 static void __tsc200x_disable(struct tsc200x *ts)
239 {
240 	tsc200x_stop_scan(ts);
241 
242 	disable_irq(ts->irq);
243 	del_timer_sync(&ts->penup_timer);
244 
245 	cancel_delayed_work_sync(&ts->esd_work);
246 
247 	enable_irq(ts->irq);
248 }
249 
250 /* must be called with ts->mutex held */
251 static void __tsc200x_enable(struct tsc200x *ts)
252 {
253 	tsc200x_start_scan(ts);
254 
255 	if (ts->esd_timeout && ts->reset_gpio) {
256 		ts->last_valid_interrupt = jiffies;
257 		schedule_delayed_work(&ts->esd_work,
258 				round_jiffies_relative(
259 					msecs_to_jiffies(ts->esd_timeout)));
260 	}
261 }
262 
263 static ssize_t tsc200x_selftest_show(struct device *dev,
264 				     struct device_attribute *attr,
265 				     char *buf)
266 {
267 	struct tsc200x *ts = dev_get_drvdata(dev);
268 	unsigned int temp_high;
269 	unsigned int temp_high_orig;
270 	unsigned int temp_high_test;
271 	bool success = true;
272 	int error;
273 
274 	mutex_lock(&ts->mutex);
275 
276 	/*
277 	 * Test TSC200X communications via temp high register.
278 	 */
279 	__tsc200x_disable(ts);
280 
281 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high_orig);
282 	if (error) {
283 		dev_warn(dev, "selftest failed: read error %d\n", error);
284 		success = false;
285 		goto out;
286 	}
287 
288 	temp_high_test = (temp_high_orig - 1) & MAX_12BIT;
289 
290 	error = regmap_write(ts->regmap, TSC200X_REG_TEMP_HIGH, temp_high_test);
291 	if (error) {
292 		dev_warn(dev, "selftest failed: write error %d\n", error);
293 		success = false;
294 		goto out;
295 	}
296 
297 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
298 	if (error) {
299 		dev_warn(dev, "selftest failed: read error %d after write\n",
300 			 error);
301 		success = false;
302 		goto out;
303 	}
304 
305 	if (temp_high != temp_high_test) {
306 		dev_warn(dev, "selftest failed: %d != %d\n",
307 			 temp_high, temp_high_test);
308 		success = false;
309 	}
310 
311 	/* hardware reset */
312 	tsc200x_reset(ts);
313 
314 	if (!success)
315 		goto out;
316 
317 	/* test that the reset really happened */
318 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
319 	if (error) {
320 		dev_warn(dev, "selftest failed: read error %d after reset\n",
321 			 error);
322 		success = false;
323 		goto out;
324 	}
325 
326 	if (temp_high != temp_high_orig) {
327 		dev_warn(dev, "selftest failed after reset: %d != %d\n",
328 			 temp_high, temp_high_orig);
329 		success = false;
330 	}
331 
332 out:
333 	__tsc200x_enable(ts);
334 	mutex_unlock(&ts->mutex);
335 
336 	return sprintf(buf, "%d\n", success);
337 }
338 
339 static DEVICE_ATTR(selftest, S_IRUGO, tsc200x_selftest_show, NULL);
340 
341 static struct attribute *tsc200x_attrs[] = {
342 	&dev_attr_selftest.attr,
343 	NULL
344 };
345 
346 static umode_t tsc200x_attr_is_visible(struct kobject *kobj,
347 				      struct attribute *attr, int n)
348 {
349 	struct device *dev = container_of(kobj, struct device, kobj);
350 	struct tsc200x *ts = dev_get_drvdata(dev);
351 	umode_t mode = attr->mode;
352 
353 	if (attr == &dev_attr_selftest.attr) {
354 		if (!ts->reset_gpio)
355 			mode = 0;
356 	}
357 
358 	return mode;
359 }
360 
361 static const struct attribute_group tsc200x_attr_group = {
362 	.is_visible	= tsc200x_attr_is_visible,
363 	.attrs		= tsc200x_attrs,
364 };
365 
366 static void tsc200x_esd_work(struct work_struct *work)
367 {
368 	struct tsc200x *ts = container_of(work, struct tsc200x, esd_work.work);
369 	int error;
370 	unsigned int r;
371 
372 	if (!mutex_trylock(&ts->mutex)) {
373 		/*
374 		 * If the mutex is taken, it means that disable or enable is in
375 		 * progress. In that case just reschedule the work. If the work
376 		 * is not needed, it will be canceled by disable.
377 		 */
378 		goto reschedule;
379 	}
380 
381 	if (time_is_after_jiffies(ts->last_valid_interrupt +
382 				  msecs_to_jiffies(ts->esd_timeout)))
383 		goto out;
384 
385 	/* We should be able to read register without disabling interrupts. */
386 	error = regmap_read(ts->regmap, TSC200X_REG_CFR0, &r);
387 	if (!error &&
388 	    !((r ^ TSC200X_CFR0_INITVALUE) & TSC200X_CFR0_RW_MASK)) {
389 		goto out;
390 	}
391 
392 	/*
393 	 * If we could not read our known value from configuration register 0
394 	 * then we should reset the controller as if from power-up and start
395 	 * scanning again.
396 	 */
397 	dev_info(ts->dev, "TSC200X not responding - resetting\n");
398 
399 	disable_irq(ts->irq);
400 	del_timer_sync(&ts->penup_timer);
401 
402 	tsc200x_update_pen_state(ts, 0, 0, 0);
403 
404 	tsc200x_reset(ts);
405 
406 	enable_irq(ts->irq);
407 	tsc200x_start_scan(ts);
408 
409 out:
410 	mutex_unlock(&ts->mutex);
411 reschedule:
412 	/* re-arm the watchdog */
413 	schedule_delayed_work(&ts->esd_work,
414 			      round_jiffies_relative(
415 					msecs_to_jiffies(ts->esd_timeout)));
416 }
417 
418 static int tsc200x_open(struct input_dev *input)
419 {
420 	struct tsc200x *ts = input_get_drvdata(input);
421 
422 	mutex_lock(&ts->mutex);
423 
424 	if (!ts->suspended)
425 		__tsc200x_enable(ts);
426 
427 	ts->opened = true;
428 
429 	mutex_unlock(&ts->mutex);
430 
431 	return 0;
432 }
433 
434 static void tsc200x_close(struct input_dev *input)
435 {
436 	struct tsc200x *ts = input_get_drvdata(input);
437 
438 	mutex_lock(&ts->mutex);
439 
440 	if (!ts->suspended)
441 		__tsc200x_disable(ts);
442 
443 	ts->opened = false;
444 
445 	mutex_unlock(&ts->mutex);
446 }
447 
448 int tsc200x_probe(struct device *dev, int irq, const struct input_id *tsc_id,
449 		  struct regmap *regmap,
450 		  int (*tsc200x_cmd)(struct device *dev, u8 cmd))
451 {
452 	struct tsc200x *ts;
453 	struct input_dev *input_dev;
454 	u32 x_plate_ohm;
455 	u32 esd_timeout;
456 	int error;
457 
458 	if (irq <= 0) {
459 		dev_err(dev, "no irq\n");
460 		return -ENODEV;
461 	}
462 
463 	if (IS_ERR(regmap))
464 		return PTR_ERR(regmap);
465 
466 	if (!tsc200x_cmd) {
467 		dev_err(dev, "no cmd function\n");
468 		return -ENODEV;
469 	}
470 
471 	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
472 	if (!ts)
473 		return -ENOMEM;
474 
475 	input_dev = devm_input_allocate_device(dev);
476 	if (!input_dev)
477 		return -ENOMEM;
478 
479 	ts->irq = irq;
480 	ts->dev = dev;
481 	ts->idev = input_dev;
482 	ts->regmap = regmap;
483 	ts->tsc200x_cmd = tsc200x_cmd;
484 
485 	error = device_property_read_u32(dev, "ti,x-plate-ohms", &x_plate_ohm);
486 	ts->x_plate_ohm = error ? TSC200X_DEF_RESISTOR : x_plate_ohm;
487 
488 	error = device_property_read_u32(dev, "ti,esd-recovery-timeout-ms",
489 					 &esd_timeout);
490 	ts->esd_timeout = error ? 0 : esd_timeout;
491 
492 	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
493 	if (IS_ERR(ts->reset_gpio)) {
494 		error = PTR_ERR(ts->reset_gpio);
495 		dev_err(dev, "error acquiring reset gpio: %d\n", error);
496 		return error;
497 	}
498 
499 	ts->vio = devm_regulator_get(dev, "vio");
500 	if (IS_ERR(ts->vio)) {
501 		error = PTR_ERR(ts->vio);
502 		dev_err(dev, "error acquiring vio regulator: %d", error);
503 		return error;
504 	}
505 
506 	mutex_init(&ts->mutex);
507 
508 	spin_lock_init(&ts->lock);
509 	timer_setup(&ts->penup_timer, tsc200x_penup_timer, 0);
510 
511 	INIT_DELAYED_WORK(&ts->esd_work, tsc200x_esd_work);
512 
513 	snprintf(ts->phys, sizeof(ts->phys),
514 		 "%s/input-ts", dev_name(dev));
515 
516 	if (tsc_id->product == 2004) {
517 		input_dev->name = "TSC200X touchscreen";
518 	} else {
519 		input_dev->name = devm_kasprintf(dev, GFP_KERNEL,
520 						 "TSC%04d touchscreen",
521 						 tsc_id->product);
522 		if (!input_dev->name)
523 			return -ENOMEM;
524 	}
525 
526 	input_dev->phys = ts->phys;
527 	input_dev->id = *tsc_id;
528 
529 	input_dev->open = tsc200x_open;
530 	input_dev->close = tsc200x_close;
531 
532 	input_set_drvdata(input_dev, ts);
533 
534 	__set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
535 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
536 
537 	input_set_abs_params(input_dev, ABS_X,
538 			     0, MAX_12BIT, TSC200X_DEF_X_FUZZ, 0);
539 	input_set_abs_params(input_dev, ABS_Y,
540 			     0, MAX_12BIT, TSC200X_DEF_Y_FUZZ, 0);
541 	input_set_abs_params(input_dev, ABS_PRESSURE,
542 			     0, MAX_12BIT, TSC200X_DEF_P_FUZZ, 0);
543 
544 	touchscreen_parse_properties(input_dev, false, NULL);
545 
546 	/* Ensure the touchscreen is off */
547 	tsc200x_stop_scan(ts);
548 
549 	error = devm_request_threaded_irq(dev, irq, NULL,
550 					  tsc200x_irq_thread,
551 					  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
552 					  "tsc200x", ts);
553 	if (error) {
554 		dev_err(dev, "Failed to request irq, err: %d\n", error);
555 		return error;
556 	}
557 
558 	error = regulator_enable(ts->vio);
559 	if (error)
560 		return error;
561 
562 	dev_set_drvdata(dev, ts);
563 	error = sysfs_create_group(&dev->kobj, &tsc200x_attr_group);
564 	if (error) {
565 		dev_err(dev,
566 			"Failed to create sysfs attributes, err: %d\n", error);
567 		goto disable_regulator;
568 	}
569 
570 	error = input_register_device(ts->idev);
571 	if (error) {
572 		dev_err(dev,
573 			"Failed to register input device, err: %d\n", error);
574 		goto err_remove_sysfs;
575 	}
576 
577 	irq_set_irq_wake(irq, 1);
578 	return 0;
579 
580 err_remove_sysfs:
581 	sysfs_remove_group(&dev->kobj, &tsc200x_attr_group);
582 disable_regulator:
583 	regulator_disable(ts->vio);
584 	return error;
585 }
586 EXPORT_SYMBOL_GPL(tsc200x_probe);
587 
588 int tsc200x_remove(struct device *dev)
589 {
590 	struct tsc200x *ts = dev_get_drvdata(dev);
591 
592 	sysfs_remove_group(&dev->kobj, &tsc200x_attr_group);
593 
594 	regulator_disable(ts->vio);
595 
596 	return 0;
597 }
598 EXPORT_SYMBOL_GPL(tsc200x_remove);
599 
600 static int __maybe_unused tsc200x_suspend(struct device *dev)
601 {
602 	struct tsc200x *ts = dev_get_drvdata(dev);
603 
604 	mutex_lock(&ts->mutex);
605 
606 	if (!ts->suspended && ts->opened)
607 		__tsc200x_disable(ts);
608 
609 	ts->suspended = true;
610 
611 	mutex_unlock(&ts->mutex);
612 
613 	return 0;
614 }
615 
616 static int __maybe_unused tsc200x_resume(struct device *dev)
617 {
618 	struct tsc200x *ts = dev_get_drvdata(dev);
619 
620 	mutex_lock(&ts->mutex);
621 
622 	if (ts->suspended && ts->opened)
623 		__tsc200x_enable(ts);
624 
625 	ts->suspended = false;
626 
627 	mutex_unlock(&ts->mutex);
628 
629 	return 0;
630 }
631 
632 SIMPLE_DEV_PM_OPS(tsc200x_pm_ops, tsc200x_suspend, tsc200x_resume);
633 EXPORT_SYMBOL_GPL(tsc200x_pm_ops);
634 
635 MODULE_AUTHOR("Lauri Leukkunen <lauri.leukkunen@nokia.com>");
636 MODULE_DESCRIPTION("TSC200x Touchscreen Driver Core");
637 MODULE_LICENSE("GPL");
638