xref: /linux/drivers/input/touchscreen/tsc200x-core.c (revision e3966940559d52aa1800a008dcfeec218dd31f88) 
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/export.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/input.h>
17 #include <linux/input/touchscreen.h>
18 #include <linux/interrupt.h>
19 #include <linux/delay.h>
20 #include <linux/pm.h>
21 #include <linux/of.h>
22 #include <linux/regulator/consumer.h>
23 #include <linux/regmap.h>
24 #include <linux/gpio/consumer.h>
25 #include "tsc200x-core.h"
26 
27 /*
28  * The touchscreen interface operates as follows:
29  *
30  * 1) Pen is pressed against the touchscreen.
31  * 2) TSC200X performs AD conversion.
32  * 3) After the conversion is done TSC200X drives DAV line down.
33  * 4) GPIO IRQ is received and tsc200x_irq_thread() is scheduled.
34  * 5) tsc200x_irq_thread() queues up a transfer to fetch the x, y, z1, z2
35  *    values.
36  * 6) tsc200x_irq_thread() reports coordinates to input layer and sets up
37  *    tsc200x_penup_timer() to be called after TSC200X_PENUP_TIME_MS (40ms).
38  * 7) When the penup timer expires, there have not been touch or DAV interrupts
39  *    during the last 40ms which means the pen has been lifted.
40  *
41  * ESD recovery via a hardware reset is done if the TSC200X doesn't respond
42  * after a configurable period (in ms) of activity. If esd_timeout is 0, the
43  * watchdog is disabled.
44  */
45 
46 static const struct regmap_range tsc200x_writable_ranges[] = {
47 	regmap_reg_range(TSC200X_REG_AUX_HIGH, TSC200X_REG_CFR2),
48 };
49 
50 static const struct regmap_access_table tsc200x_writable_table = {
51 	.yes_ranges = tsc200x_writable_ranges,
52 	.n_yes_ranges = ARRAY_SIZE(tsc200x_writable_ranges),
53 };
54 
55 const struct regmap_config tsc200x_regmap_config = {
56 	.reg_bits = 8,
57 	.val_bits = 16,
58 	.reg_stride = 0x08,
59 	.max_register = 0x78,
60 	.read_flag_mask = TSC200X_REG_READ,
61 	.write_flag_mask = TSC200X_REG_PND0,
62 	.wr_table = &tsc200x_writable_table,
63 	.use_single_read = true,
64 	.use_single_write = true,
65 };
66 EXPORT_SYMBOL_GPL(tsc200x_regmap_config);
67 
68 struct tsc200x_data {
69 	u16 x;
70 	u16 y;
71 	u16 z1;
72 	u16 z2;
73 } __packed;
74 #define TSC200X_DATA_REGS 4
75 
76 struct tsc200x {
77 	struct device           *dev;
78 	struct regmap		*regmap;
79 	__u16                   bustype;
80 
81 	struct input_dev	*idev;
82 	char			phys[32];
83 
84 	struct mutex		mutex;
85 
86 	/* raw copy of previous x,y,z */
87 	int			in_x;
88 	int			in_y;
89 	int                     in_z1;
90 	int			in_z2;
91 
92 	struct touchscreen_properties prop;
93 
94 	spinlock_t		lock;
95 	struct timer_list	penup_timer;
96 
97 	unsigned int		esd_timeout;
98 	struct delayed_work	esd_work;
99 	unsigned long		last_valid_interrupt;
100 
101 	unsigned int		x_plate_ohm;
102 
103 	bool			opened;
104 	bool			suspended;
105 
106 	bool			pen_down;
107 
108 	struct gpio_desc	*reset_gpio;
109 	int			(*tsc200x_cmd)(struct device *dev, u8 cmd);
110 
111 	int			irq;
112 	bool			wake_irq_enabled;
113 };
114 
115 static void tsc200x_update_pen_state(struct tsc200x *ts,
116 				     int x, int y, int pressure)
117 {
118 	if (pressure) {
119 		touchscreen_report_pos(ts->idev, &ts->prop, x, y, false);
120 		input_report_abs(ts->idev, ABS_PRESSURE, pressure);
121 		if (!ts->pen_down) {
122 			input_report_key(ts->idev, BTN_TOUCH, !!pressure);
123 			ts->pen_down = true;
124 		}
125 	} else {
126 		input_report_abs(ts->idev, ABS_PRESSURE, 0);
127 		if (ts->pen_down) {
128 			input_report_key(ts->idev, BTN_TOUCH, 0);
129 			ts->pen_down = false;
130 		}
131 	}
132 	input_sync(ts->idev);
133 	dev_dbg(ts->dev, "point(%4d,%4d), pressure (%4d)\n", x, y,
134 		pressure);
135 }
136 
137 static irqreturn_t tsc200x_irq_thread(int irq, void *_ts)
138 {
139 	struct tsc200x *ts = _ts;
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 	scoped_guard(spinlock_irqsave, &ts->lock) {
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 
191 	ts->last_valid_interrupt = jiffies;
192 out:
193 	return IRQ_HANDLED;
194 }
195 
196 static void tsc200x_penup_timer(struct timer_list *t)
197 {
198 	struct tsc200x *ts = timer_container_of(ts, t, penup_timer);
199 
200 	guard(spinlock_irqsave)(&ts->lock);
201 	tsc200x_update_pen_state(ts, 0, 0, 0);
202 }
203 
204 static void tsc200x_start_scan(struct tsc200x *ts)
205 {
206 	regmap_write(ts->regmap, TSC200X_REG_CFR0, TSC200X_CFR0_INITVALUE);
207 	regmap_write(ts->regmap, TSC200X_REG_CFR1, TSC200X_CFR1_INITVALUE);
208 	regmap_write(ts->regmap, TSC200X_REG_CFR2, TSC200X_CFR2_INITVALUE);
209 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_NORMAL);
210 }
211 
212 static void tsc200x_stop_scan(struct tsc200x *ts)
213 {
214 	ts->tsc200x_cmd(ts->dev, TSC200X_CMD_STOP);
215 }
216 
217 static void tsc200x_reset(struct tsc200x *ts)
218 {
219 	if (ts->reset_gpio) {
220 		gpiod_set_value_cansleep(ts->reset_gpio, 1);
221 		usleep_range(100, 500); /* only 10us required */
222 		gpiod_set_value_cansleep(ts->reset_gpio, 0);
223 	}
224 }
225 
226 /* must be called with ts->mutex held */
227 static void __tsc200x_disable(struct tsc200x *ts)
228 {
229 	tsc200x_stop_scan(ts);
230 
231 	guard(disable_irq)(&ts->irq);
232 
233 	timer_delete_sync(&ts->penup_timer);
234 	cancel_delayed_work_sync(&ts->esd_work);
235 }
236 
237 /* must be called with ts->mutex held */
238 static void __tsc200x_enable(struct tsc200x *ts)
239 {
240 	tsc200x_start_scan(ts);
241 
242 	if (ts->esd_timeout && ts->reset_gpio) {
243 		ts->last_valid_interrupt = jiffies;
244 		schedule_delayed_work(&ts->esd_work,
245 				round_jiffies_relative(
246 					msecs_to_jiffies(ts->esd_timeout)));
247 	}
248 }
249 
250 /*
251  * Test TSC200X communications via temp high register.
252  */
253 static int tsc200x_do_selftest(struct tsc200x *ts)
254 {
255 	unsigned int temp_high_orig;
256 	unsigned int temp_high_test;
257 	unsigned int temp_high;
258 	int error;
259 
260 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high_orig);
261 	if (error) {
262 		dev_warn(ts->dev, "selftest failed: read error %d\n", error);
263 		return error;
264 	}
265 
266 	temp_high_test = (temp_high_orig - 1) & MAX_12BIT;
267 
268 	error = regmap_write(ts->regmap, TSC200X_REG_TEMP_HIGH, temp_high_test);
269 	if (error) {
270 		dev_warn(ts->dev, "selftest failed: write error %d\n", error);
271 		return error;
272 	}
273 
274 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
275 	if (error) {
276 		dev_warn(ts->dev,
277 			 "selftest failed: read error %d after write\n", error);
278 		return error;
279 	}
280 
281 	/* hardware reset */
282 	tsc200x_reset(ts);
283 
284 	if (temp_high != temp_high_test) {
285 		dev_warn(ts->dev, "selftest failed: %d != %d\n",
286 			 temp_high, temp_high_test);
287 		return -EINVAL;
288 	}
289 
290 	/* test that the reset really happened */
291 	error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
292 	if (error) {
293 		dev_warn(ts->dev,
294 			 "selftest failed: read error %d after reset\n", error);
295 		return error;
296 	}
297 
298 	if (temp_high != temp_high_orig) {
299 		dev_warn(ts->dev, "selftest failed after reset: %d != %d\n",
300 			 temp_high, temp_high_orig);
301 		return -EINVAL;
302 	}
303 
304 	return 0;
305 }
306 
307 static ssize_t tsc200x_selftest_show(struct device *dev,
308 				     struct device_attribute *attr,
309 				     char *buf)
310 {
311 	struct tsc200x *ts = dev_get_drvdata(dev);
312 	int error;
313 
314 	scoped_guard(mutex, &ts->mutex) {
315 		__tsc200x_disable(ts);
316 
317 		error = tsc200x_do_selftest(ts);
318 
319 		__tsc200x_enable(ts);
320 	}
321 
322 	return sprintf(buf, "%d\n", !error);
323 }
324 
325 static DEVICE_ATTR(selftest, S_IRUGO, tsc200x_selftest_show, NULL);
326 
327 static struct attribute *tsc200x_attrs[] = {
328 	&dev_attr_selftest.attr,
329 	NULL
330 };
331 
332 static umode_t tsc200x_attr_is_visible(struct kobject *kobj,
333 				      struct attribute *attr, int n)
334 {
335 	struct device *dev = kobj_to_dev(kobj);
336 	struct tsc200x *ts = dev_get_drvdata(dev);
337 	umode_t mode = attr->mode;
338 
339 	if (attr == &dev_attr_selftest.attr) {
340 		if (!ts->reset_gpio)
341 			mode = 0;
342 	}
343 
344 	return mode;
345 }
346 
347 static const struct attribute_group tsc200x_attr_group = {
348 	.is_visible	= tsc200x_attr_is_visible,
349 	.attrs		= tsc200x_attrs,
350 };
351 
352 const struct attribute_group *tsc200x_groups[] = {
353 	&tsc200x_attr_group,
354 	NULL
355 };
356 EXPORT_SYMBOL_GPL(tsc200x_groups);
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 	/*
365 	 * If the mutex is taken, it means that disable or enable is in
366 	 * progress. In that case just reschedule the work. If the work
367 	 * is not needed, it will be canceled by disable.
368 	 */
369 	scoped_guard(mutex_try, &ts->mutex) {
370 		if (time_is_after_jiffies(ts->last_valid_interrupt +
371 					  msecs_to_jiffies(ts->esd_timeout)))
372 			break;
373 
374 		/*
375 		 * We should be able to read register without disabling
376 		 * interrupts.
377 		 */
378 		error = regmap_read(ts->regmap, TSC200X_REG_CFR0, &r);
379 		if (!error &&
380 		    !((r ^ TSC200X_CFR0_INITVALUE) & TSC200X_CFR0_RW_MASK)) {
381 			break;
382 		}
383 
384 		/*
385 		 * If we could not read our known value from configuration
386 		 * register 0 then we should reset the controller as if from
387 		 * power-up and start scanning again.
388 		 */
389 		dev_info(ts->dev, "TSC200X not responding - resetting\n");
390 
391 		scoped_guard(disable_irq, &ts->irq) {
392 			timer_delete_sync(&ts->penup_timer);
393 			tsc200x_update_pen_state(ts, 0, 0, 0);
394 			tsc200x_reset(ts);
395 		}
396 
397 		tsc200x_start_scan(ts);
398 	}
399 
400 	/* re-arm the watchdog */
401 	schedule_delayed_work(&ts->esd_work,
402 			      round_jiffies_relative(
403 					msecs_to_jiffies(ts->esd_timeout)));
404 }
405 
406 static int tsc200x_open(struct input_dev *input)
407 {
408 	struct tsc200x *ts = input_get_drvdata(input);
409 
410 	guard(mutex)(&ts->mutex);
411 
412 	if (!ts->suspended)
413 		__tsc200x_enable(ts);
414 
415 	ts->opened = true;
416 
417 	return 0;
418 }
419 
420 static void tsc200x_close(struct input_dev *input)
421 {
422 	struct tsc200x *ts = input_get_drvdata(input);
423 
424 	guard(mutex)(&ts->mutex);
425 
426 	if (!ts->suspended)
427 		__tsc200x_disable(ts);
428 
429 	ts->opened = false;
430 }
431 
432 int tsc200x_probe(struct device *dev, int irq, const struct input_id *tsc_id,
433 		  struct regmap *regmap,
434 		  int (*tsc200x_cmd)(struct device *dev, u8 cmd))
435 {
436 	struct tsc200x *ts;
437 	struct input_dev *input_dev;
438 	u32 x_plate_ohm;
439 	u32 esd_timeout;
440 	int error;
441 
442 	if (irq <= 0) {
443 		dev_err(dev, "no irq\n");
444 		return -ENODEV;
445 	}
446 
447 	if (IS_ERR(regmap))
448 		return PTR_ERR(regmap);
449 
450 	if (!tsc200x_cmd) {
451 		dev_err(dev, "no cmd function\n");
452 		return -ENODEV;
453 	}
454 
455 	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
456 	if (!ts)
457 		return -ENOMEM;
458 
459 	input_dev = devm_input_allocate_device(dev);
460 	if (!input_dev)
461 		return -ENOMEM;
462 
463 	ts->irq = irq;
464 	ts->dev = dev;
465 	ts->idev = input_dev;
466 	ts->regmap = regmap;
467 	ts->tsc200x_cmd = tsc200x_cmd;
468 
469 	error = device_property_read_u32(dev, "ti,x-plate-ohms", &x_plate_ohm);
470 	ts->x_plate_ohm = error ? TSC200X_DEF_RESISTOR : x_plate_ohm;
471 
472 	error = device_property_read_u32(dev, "ti,esd-recovery-timeout-ms",
473 					 &esd_timeout);
474 	ts->esd_timeout = error ? 0 : esd_timeout;
475 
476 	mutex_init(&ts->mutex);
477 
478 	spin_lock_init(&ts->lock);
479 	timer_setup(&ts->penup_timer, tsc200x_penup_timer, 0);
480 
481 	INIT_DELAYED_WORK(&ts->esd_work, tsc200x_esd_work);
482 
483 	snprintf(ts->phys, sizeof(ts->phys),
484 		 "%s/input-ts", dev_name(dev));
485 
486 	if (tsc_id->product == 2004) {
487 		input_dev->name = "TSC200X touchscreen";
488 	} else {
489 		input_dev->name = devm_kasprintf(dev, GFP_KERNEL,
490 						 "TSC%04d touchscreen",
491 						 tsc_id->product);
492 		if (!input_dev->name)
493 			return -ENOMEM;
494 	}
495 
496 	input_dev->phys = ts->phys;
497 	input_dev->id = *tsc_id;
498 
499 	input_dev->open = tsc200x_open;
500 	input_dev->close = tsc200x_close;
501 
502 	input_set_drvdata(input_dev, ts);
503 
504 	__set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
505 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
506 
507 	input_set_abs_params(input_dev, ABS_X,
508 			     0, MAX_12BIT, TSC200X_DEF_X_FUZZ, 0);
509 	input_set_abs_params(input_dev, ABS_Y,
510 			     0, MAX_12BIT, TSC200X_DEF_Y_FUZZ, 0);
511 	input_set_abs_params(input_dev, ABS_PRESSURE,
512 			     0, MAX_12BIT, TSC200X_DEF_P_FUZZ, 0);
513 
514 	touchscreen_parse_properties(input_dev, false, &ts->prop);
515 
516 	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
517 	error = PTR_ERR_OR_ZERO(ts->reset_gpio);
518 	if (error) {
519 		dev_err(dev, "error acquiring reset gpio: %d\n", error);
520 		return error;
521 	}
522 
523 	error = devm_regulator_get_enable(dev, "vio");
524 	if (error) {
525 		dev_err(dev, "error acquiring vio regulator: %d\n", error);
526 		return error;
527 	}
528 
529 	tsc200x_reset(ts);
530 
531 	/* Ensure the touchscreen is off */
532 	tsc200x_stop_scan(ts);
533 
534 	error = devm_request_threaded_irq(dev, irq, NULL, tsc200x_irq_thread,
535 					  IRQF_ONESHOT, "tsc200x", ts);
536 	if (error) {
537 		dev_err(dev, "Failed to request irq, err: %d\n", error);
538 		return error;
539 	}
540 
541 	dev_set_drvdata(dev, ts);
542 
543 	error = input_register_device(ts->idev);
544 	if (error) {
545 		dev_err(dev,
546 			"Failed to register input device, err: %d\n", error);
547 		return error;
548 	}
549 
550 	device_init_wakeup(dev,
551 			   device_property_read_bool(dev, "wakeup-source"));
552 
553 	return 0;
554 }
555 EXPORT_SYMBOL_GPL(tsc200x_probe);
556 
557 static int tsc200x_suspend(struct device *dev)
558 {
559 	struct tsc200x *ts = dev_get_drvdata(dev);
560 
561 	guard(mutex)(&ts->mutex);
562 
563 	if (!ts->suspended && ts->opened)
564 		__tsc200x_disable(ts);
565 
566 	ts->suspended = true;
567 
568 	if (device_may_wakeup(dev))
569 		ts->wake_irq_enabled = enable_irq_wake(ts->irq) == 0;
570 
571 	return 0;
572 }
573 
574 static int tsc200x_resume(struct device *dev)
575 {
576 	struct tsc200x *ts = dev_get_drvdata(dev);
577 
578 	guard(mutex)(&ts->mutex);
579 
580 	if (ts->wake_irq_enabled) {
581 		disable_irq_wake(ts->irq);
582 		ts->wake_irq_enabled = false;
583 	}
584 
585 	if (ts->suspended && ts->opened)
586 		__tsc200x_enable(ts);
587 
588 	ts->suspended = false;
589 
590 	return 0;
591 }
592 
593 EXPORT_GPL_SIMPLE_DEV_PM_OPS(tsc200x_pm_ops, tsc200x_suspend, tsc200x_resume);
594 
595 MODULE_AUTHOR("Lauri Leukkunen <lauri.leukkunen@nokia.com>");
596 MODULE_DESCRIPTION("TSC200x Touchscreen Driver Core");
597 MODULE_LICENSE("GPL");
598