1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * ADS7846 based touchscreen and sensor driver
4  *
5  * Copyright (c) 2005 David Brownell
6  * Copyright (c) 2006 Nokia Corporation
7  * Various changes: Imre Deak <imre.deak@nokia.com>
8  *
9  * Using code from:
10  *  - corgi_ts.c
11  *	Copyright (C) 2004-2005 Richard Purdie
12  *  - omap_ts.[hc], ads7846.h, ts_osk.c
13  *	Copyright (C) 2002 MontaVista Software
14  *	Copyright (C) 2004 Texas Instruments
15  *	Copyright (C) 2005 Dirk Behme
16  */
17 #include <linux/types.h>
18 #include <linux/hwmon.h>
19 #include <linux/err.h>
20 #include <linux/sched.h>
21 #include <linux/delay.h>
22 #include <linux/input.h>
23 #include <linux/input/touchscreen.h>
24 #include <linux/interrupt.h>
25 #include <linux/slab.h>
26 #include <linux/pm.h>
27 #include <linux/of.h>
28 #include <linux/of_gpio.h>
29 #include <linux/of_device.h>
30 #include <linux/gpio.h>
31 #include <linux/spi/spi.h>
32 #include <linux/spi/ads7846.h>
33 #include <linux/regulator/consumer.h>
34 #include <linux/module.h>
35 #include <asm/unaligned.h>
36 
37 /*
38  * This code has been heavily tested on a Nokia 770, and lightly
39  * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
40  * TSC2046 is just newer ads7846 silicon.
41  * Support for ads7843 tested on Atmel at91sam926x-EK.
42  * Support for ads7845 has only been stubbed in.
43  * Support for Analog Devices AD7873 and AD7843 tested.
44  *
45  * IRQ handling needs a workaround because of a shortcoming in handling
46  * edge triggered IRQs on some platforms like the OMAP1/2. These
47  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
48  * have to maintain our own SW IRQ disabled status. This should be
49  * removed as soon as the affected platform's IRQ handling is fixed.
50  *
51  * App note sbaa036 talks in more detail about accurate sampling...
52  * that ought to help in situations like LCDs inducing noise (which
53  * can also be helped by using synch signals) and more generally.
54  * This driver tries to utilize the measures described in the app
55  * note. The strength of filtering can be set in the board-* specific
56  * files.
57  */
58 
59 #define TS_POLL_DELAY	1	/* ms delay before the first sample */
60 #define TS_POLL_PERIOD	5	/* ms delay between samples */
61 
62 /* this driver doesn't aim at the peak continuous sample rate */
63 #define	SAMPLE_BITS	(8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
64 
65 struct ads7846_buf {
66 	u8 cmd;
67 	__be16 data;
68 } __packed;
69 
70 struct ads7846_buf_layout {
71 	unsigned int offset;
72 	unsigned int count;
73 	unsigned int skip;
74 };
75 
76 /*
77  * We allocate this separately to avoid cache line sharing issues when
78  * driver is used with DMA-based SPI controllers (like atmel_spi) on
79  * systems where main memory is not DMA-coherent (most non-x86 boards).
80  */
81 struct ads7846_packet {
82 	unsigned int count;
83 	unsigned int count_skip;
84 	unsigned int cmds;
85 	unsigned int last_cmd_idx;
86 	struct ads7846_buf_layout l[5];
87 	struct ads7846_buf *rx;
88 	struct ads7846_buf *tx;
89 
90 	struct ads7846_buf pwrdown_cmd;
91 
92 	bool ignore;
93 	u16 x, y, z1, z2;
94 };
95 
96 struct ads7846 {
97 	struct input_dev	*input;
98 	char			phys[32];
99 	char			name[32];
100 
101 	struct spi_device	*spi;
102 	struct regulator	*reg;
103 
104 	u16			model;
105 	u16			vref_mv;
106 	u16			vref_delay_usecs;
107 	u16			x_plate_ohms;
108 	u16			pressure_max;
109 
110 	bool			swap_xy;
111 	bool			use_internal;
112 
113 	struct ads7846_packet	*packet;
114 
115 	struct spi_transfer	xfer[18];
116 	struct spi_message	msg[5];
117 	int			msg_count;
118 	wait_queue_head_t	wait;
119 
120 	bool			pendown;
121 
122 	int			read_cnt;
123 	int			read_rep;
124 	int			last_read;
125 
126 	u16			debounce_max;
127 	u16			debounce_tol;
128 	u16			debounce_rep;
129 
130 	u16			penirq_recheck_delay_usecs;
131 
132 	struct touchscreen_properties core_prop;
133 
134 	struct mutex		lock;
135 	bool			stopped;	/* P: lock */
136 	bool			disabled;	/* P: lock */
137 	bool			suspended;	/* P: lock */
138 
139 	int			(*filter)(void *data, int data_idx, int *val);
140 	void			*filter_data;
141 	int			(*get_pendown_state)(void);
142 	int			gpio_pendown;
143 
144 	void			(*wait_for_sync)(void);
145 };
146 
147 enum ads7846_filter {
148 	ADS7846_FILTER_OK,
149 	ADS7846_FILTER_REPEAT,
150 	ADS7846_FILTER_IGNORE,
151 };
152 
153 /* leave chip selected when we're done, for quicker re-select? */
154 #if	0
155 #define	CS_CHANGE(xfer)	((xfer).cs_change = 1)
156 #else
157 #define	CS_CHANGE(xfer)	((xfer).cs_change = 0)
158 #endif
159 
160 /*--------------------------------------------------------------------------*/
161 
162 /* The ADS7846 has touchscreen and other sensors.
163  * Earlier ads784x chips are somewhat compatible.
164  */
165 #define	ADS_START		(1 << 7)
166 #define	ADS_A2A1A0_d_y		(1 << 4)	/* differential */
167 #define	ADS_A2A1A0_d_z1		(3 << 4)	/* differential */
168 #define	ADS_A2A1A0_d_z2		(4 << 4)	/* differential */
169 #define	ADS_A2A1A0_d_x		(5 << 4)	/* differential */
170 #define	ADS_A2A1A0_temp0	(0 << 4)	/* non-differential */
171 #define	ADS_A2A1A0_vbatt	(2 << 4)	/* non-differential */
172 #define	ADS_A2A1A0_vaux		(6 << 4)	/* non-differential */
173 #define	ADS_A2A1A0_temp1	(7 << 4)	/* non-differential */
174 #define	ADS_8_BIT		(1 << 3)
175 #define	ADS_12_BIT		(0 << 3)
176 #define	ADS_SER			(1 << 2)	/* non-differential */
177 #define	ADS_DFR			(0 << 2)	/* differential */
178 #define	ADS_PD10_PDOWN		(0 << 0)	/* low power mode + penirq */
179 #define	ADS_PD10_ADC_ON		(1 << 0)	/* ADC on */
180 #define	ADS_PD10_REF_ON		(2 << 0)	/* vREF on + penirq */
181 #define	ADS_PD10_ALL_ON		(3 << 0)	/* ADC + vREF on */
182 
183 #define	MAX_12BIT	((1<<12)-1)
184 
185 /* leave ADC powered up (disables penirq) between differential samples */
186 #define	READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
187 	| ADS_12_BIT | ADS_DFR | \
188 	(adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
189 
190 #define	READ_Y(vref)	(READ_12BIT_DFR(y,  1, vref))
191 #define	READ_Z1(vref)	(READ_12BIT_DFR(z1, 1, vref))
192 #define	READ_Z2(vref)	(READ_12BIT_DFR(z2, 1, vref))
193 #define	READ_X(vref)	(READ_12BIT_DFR(x,  1, vref))
194 #define	PWRDOWN		(READ_12BIT_DFR(y,  0, 0))	/* LAST */
195 
196 /* single-ended samples need to first power up reference voltage;
197  * we leave both ADC and VREF powered
198  */
199 #define	READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
200 	| ADS_12_BIT | ADS_SER)
201 
202 #define	REF_ON	(READ_12BIT_DFR(x, 1, 1))
203 #define	REF_OFF	(READ_12BIT_DFR(y, 0, 0))
204 
205 /* Order commands in the most optimal way to reduce Vref switching and
206  * settling time:
207  * Measure:  X; Vref: X+, X-; IN: Y+
208  * Measure:  Y; Vref: Y+, Y-; IN: X+
209  * Measure: Z1; Vref: Y+, X-; IN: X+
210  * Measure: Z2; Vref: Y+, X-; IN: Y-
211  */
212 enum ads7846_cmds {
213 	ADS7846_X,
214 	ADS7846_Y,
215 	ADS7846_Z1,
216 	ADS7846_Z2,
217 	ADS7846_PWDOWN,
218 };
219 
220 static int get_pendown_state(struct ads7846 *ts)
221 {
222 	if (ts->get_pendown_state)
223 		return ts->get_pendown_state();
224 
225 	return !gpio_get_value(ts->gpio_pendown);
226 }
227 
228 static void ads7846_report_pen_up(struct ads7846 *ts)
229 {
230 	struct input_dev *input = ts->input;
231 
232 	input_report_key(input, BTN_TOUCH, 0);
233 	input_report_abs(input, ABS_PRESSURE, 0);
234 	input_sync(input);
235 
236 	ts->pendown = false;
237 	dev_vdbg(&ts->spi->dev, "UP\n");
238 }
239 
240 /* Must be called with ts->lock held */
241 static void ads7846_stop(struct ads7846 *ts)
242 {
243 	if (!ts->disabled && !ts->suspended) {
244 		/* Signal IRQ thread to stop polling and disable the handler. */
245 		ts->stopped = true;
246 		mb();
247 		wake_up(&ts->wait);
248 		disable_irq(ts->spi->irq);
249 	}
250 }
251 
252 /* Must be called with ts->lock held */
253 static void ads7846_restart(struct ads7846 *ts)
254 {
255 	if (!ts->disabled && !ts->suspended) {
256 		/* Check if pen was released since last stop */
257 		if (ts->pendown && !get_pendown_state(ts))
258 			ads7846_report_pen_up(ts);
259 
260 		/* Tell IRQ thread that it may poll the device. */
261 		ts->stopped = false;
262 		mb();
263 		enable_irq(ts->spi->irq);
264 	}
265 }
266 
267 /* Must be called with ts->lock held */
268 static void __ads7846_disable(struct ads7846 *ts)
269 {
270 	ads7846_stop(ts);
271 	regulator_disable(ts->reg);
272 
273 	/*
274 	 * We know the chip's in low power mode since we always
275 	 * leave it that way after every request
276 	 */
277 }
278 
279 /* Must be called with ts->lock held */
280 static void __ads7846_enable(struct ads7846 *ts)
281 {
282 	int error;
283 
284 	error = regulator_enable(ts->reg);
285 	if (error != 0)
286 		dev_err(&ts->spi->dev, "Failed to enable supply: %d\n", error);
287 
288 	ads7846_restart(ts);
289 }
290 
291 static void ads7846_disable(struct ads7846 *ts)
292 {
293 	mutex_lock(&ts->lock);
294 
295 	if (!ts->disabled) {
296 
297 		if  (!ts->suspended)
298 			__ads7846_disable(ts);
299 
300 		ts->disabled = true;
301 	}
302 
303 	mutex_unlock(&ts->lock);
304 }
305 
306 static void ads7846_enable(struct ads7846 *ts)
307 {
308 	mutex_lock(&ts->lock);
309 
310 	if (ts->disabled) {
311 
312 		ts->disabled = false;
313 
314 		if (!ts->suspended)
315 			__ads7846_enable(ts);
316 	}
317 
318 	mutex_unlock(&ts->lock);
319 }
320 
321 /*--------------------------------------------------------------------------*/
322 
323 /*
324  * Non-touchscreen sensors only use single-ended conversions.
325  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
326  * ads7846 lets that pin be unconnected, to use internal vREF.
327  */
328 
329 struct ser_req {
330 	u8			ref_on;
331 	u8			command;
332 	u8			ref_off;
333 	u16			scratch;
334 	struct spi_message	msg;
335 	struct spi_transfer	xfer[6];
336 	/*
337 	 * DMA (thus cache coherency maintenance) requires the
338 	 * transfer buffers to live in their own cache lines.
339 	 */
340 	__be16 sample ____cacheline_aligned;
341 };
342 
343 struct ads7845_ser_req {
344 	u8			command[3];
345 	struct spi_message	msg;
346 	struct spi_transfer	xfer[2];
347 	/*
348 	 * DMA (thus cache coherency maintenance) requires the
349 	 * transfer buffers to live in their own cache lines.
350 	 */
351 	u8 sample[3] ____cacheline_aligned;
352 };
353 
354 static int ads7846_read12_ser(struct device *dev, unsigned command)
355 {
356 	struct spi_device *spi = to_spi_device(dev);
357 	struct ads7846 *ts = dev_get_drvdata(dev);
358 	struct ser_req *req;
359 	int status;
360 
361 	req = kzalloc(sizeof *req, GFP_KERNEL);
362 	if (!req)
363 		return -ENOMEM;
364 
365 	spi_message_init(&req->msg);
366 
367 	/* maybe turn on internal vREF, and let it settle */
368 	if (ts->use_internal) {
369 		req->ref_on = REF_ON;
370 		req->xfer[0].tx_buf = &req->ref_on;
371 		req->xfer[0].len = 1;
372 		spi_message_add_tail(&req->xfer[0], &req->msg);
373 
374 		req->xfer[1].rx_buf = &req->scratch;
375 		req->xfer[1].len = 2;
376 
377 		/* for 1uF, settle for 800 usec; no cap, 100 usec.  */
378 		req->xfer[1].delay.value = ts->vref_delay_usecs;
379 		req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS;
380 		spi_message_add_tail(&req->xfer[1], &req->msg);
381 
382 		/* Enable reference voltage */
383 		command |= ADS_PD10_REF_ON;
384 	}
385 
386 	/* Enable ADC in every case */
387 	command |= ADS_PD10_ADC_ON;
388 
389 	/* take sample */
390 	req->command = (u8) command;
391 	req->xfer[2].tx_buf = &req->command;
392 	req->xfer[2].len = 1;
393 	spi_message_add_tail(&req->xfer[2], &req->msg);
394 
395 	req->xfer[3].rx_buf = &req->sample;
396 	req->xfer[3].len = 2;
397 	spi_message_add_tail(&req->xfer[3], &req->msg);
398 
399 	/* REVISIT:  take a few more samples, and compare ... */
400 
401 	/* converter in low power mode & enable PENIRQ */
402 	req->ref_off = PWRDOWN;
403 	req->xfer[4].tx_buf = &req->ref_off;
404 	req->xfer[4].len = 1;
405 	spi_message_add_tail(&req->xfer[4], &req->msg);
406 
407 	req->xfer[5].rx_buf = &req->scratch;
408 	req->xfer[5].len = 2;
409 	CS_CHANGE(req->xfer[5]);
410 	spi_message_add_tail(&req->xfer[5], &req->msg);
411 
412 	mutex_lock(&ts->lock);
413 	ads7846_stop(ts);
414 	status = spi_sync(spi, &req->msg);
415 	ads7846_restart(ts);
416 	mutex_unlock(&ts->lock);
417 
418 	if (status == 0) {
419 		/* on-wire is a must-ignore bit, a BE12 value, then padding */
420 		status = be16_to_cpu(req->sample);
421 		status = status >> 3;
422 		status &= 0x0fff;
423 	}
424 
425 	kfree(req);
426 	return status;
427 }
428 
429 static int ads7845_read12_ser(struct device *dev, unsigned command)
430 {
431 	struct spi_device *spi = to_spi_device(dev);
432 	struct ads7846 *ts = dev_get_drvdata(dev);
433 	struct ads7845_ser_req *req;
434 	int status;
435 
436 	req = kzalloc(sizeof *req, GFP_KERNEL);
437 	if (!req)
438 		return -ENOMEM;
439 
440 	spi_message_init(&req->msg);
441 
442 	req->command[0] = (u8) command;
443 	req->xfer[0].tx_buf = req->command;
444 	req->xfer[0].rx_buf = req->sample;
445 	req->xfer[0].len = 3;
446 	spi_message_add_tail(&req->xfer[0], &req->msg);
447 
448 	mutex_lock(&ts->lock);
449 	ads7846_stop(ts);
450 	status = spi_sync(spi, &req->msg);
451 	ads7846_restart(ts);
452 	mutex_unlock(&ts->lock);
453 
454 	if (status == 0) {
455 		/* BE12 value, then padding */
456 		status = get_unaligned_be16(&req->sample[1]);
457 		status = status >> 3;
458 		status &= 0x0fff;
459 	}
460 
461 	kfree(req);
462 	return status;
463 }
464 
465 #if IS_ENABLED(CONFIG_HWMON)
466 
467 #define SHOW(name, var, adjust) static ssize_t \
468 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
469 { \
470 	struct ads7846 *ts = dev_get_drvdata(dev); \
471 	ssize_t v = ads7846_read12_ser(&ts->spi->dev, \
472 			READ_12BIT_SER(var)); \
473 	if (v < 0) \
474 		return v; \
475 	return sprintf(buf, "%u\n", adjust(ts, v)); \
476 } \
477 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
478 
479 
480 /* Sysfs conventions report temperatures in millidegrees Celsius.
481  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
482  * accuracy scheme without calibration data.  For now we won't try either;
483  * userspace sees raw sensor values, and must scale/calibrate appropriately.
484  */
485 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
486 {
487 	return v;
488 }
489 
490 SHOW(temp0, temp0, null_adjust)		/* temp1_input */
491 SHOW(temp1, temp1, null_adjust)		/* temp2_input */
492 
493 
494 /* sysfs conventions report voltages in millivolts.  We can convert voltages
495  * if we know vREF.  userspace may need to scale vAUX to match the board's
496  * external resistors; we assume that vBATT only uses the internal ones.
497  */
498 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
499 {
500 	unsigned retval = v;
501 
502 	/* external resistors may scale vAUX into 0..vREF */
503 	retval *= ts->vref_mv;
504 	retval = retval >> 12;
505 
506 	return retval;
507 }
508 
509 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
510 {
511 	unsigned retval = vaux_adjust(ts, v);
512 
513 	/* ads7846 has a resistor ladder to scale this signal down */
514 	if (ts->model == 7846)
515 		retval *= 4;
516 
517 	return retval;
518 }
519 
520 SHOW(in0_input, vaux, vaux_adjust)
521 SHOW(in1_input, vbatt, vbatt_adjust)
522 
523 static umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr,
524 				  int index)
525 {
526 	struct device *dev = kobj_to_dev(kobj);
527 	struct ads7846 *ts = dev_get_drvdata(dev);
528 
529 	if (ts->model == 7843 && index < 2)	/* in0, in1 */
530 		return 0;
531 	if (ts->model == 7845 && index != 2)	/* in0 */
532 		return 0;
533 
534 	return attr->mode;
535 }
536 
537 static struct attribute *ads7846_attributes[] = {
538 	&dev_attr_temp0.attr,		/* 0 */
539 	&dev_attr_temp1.attr,		/* 1 */
540 	&dev_attr_in0_input.attr,	/* 2 */
541 	&dev_attr_in1_input.attr,	/* 3 */
542 	NULL,
543 };
544 
545 static const struct attribute_group ads7846_attr_group = {
546 	.attrs = ads7846_attributes,
547 	.is_visible = ads7846_is_visible,
548 };
549 __ATTRIBUTE_GROUPS(ads7846_attr);
550 
551 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
552 {
553 	struct device *hwmon;
554 
555 	/* hwmon sensors need a reference voltage */
556 	switch (ts->model) {
557 	case 7846:
558 		if (!ts->vref_mv) {
559 			dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
560 			ts->vref_mv = 2500;
561 			ts->use_internal = true;
562 		}
563 		break;
564 	case 7845:
565 	case 7843:
566 		if (!ts->vref_mv) {
567 			dev_warn(&spi->dev,
568 				"external vREF for ADS%d not specified\n",
569 				ts->model);
570 			return 0;
571 		}
572 		break;
573 	}
574 
575 	hwmon = devm_hwmon_device_register_with_groups(&spi->dev,
576 						       spi->modalias, ts,
577 						       ads7846_attr_groups);
578 
579 	return PTR_ERR_OR_ZERO(hwmon);
580 }
581 
582 #else
583 static inline int ads784x_hwmon_register(struct spi_device *spi,
584 					 struct ads7846 *ts)
585 {
586 	return 0;
587 }
588 #endif
589 
590 static ssize_t ads7846_pen_down_show(struct device *dev,
591 				     struct device_attribute *attr, char *buf)
592 {
593 	struct ads7846 *ts = dev_get_drvdata(dev);
594 
595 	return sprintf(buf, "%u\n", ts->pendown);
596 }
597 
598 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
599 
600 static ssize_t ads7846_disable_show(struct device *dev,
601 				     struct device_attribute *attr, char *buf)
602 {
603 	struct ads7846 *ts = dev_get_drvdata(dev);
604 
605 	return sprintf(buf, "%u\n", ts->disabled);
606 }
607 
608 static ssize_t ads7846_disable_store(struct device *dev,
609 				     struct device_attribute *attr,
610 				     const char *buf, size_t count)
611 {
612 	struct ads7846 *ts = dev_get_drvdata(dev);
613 	unsigned int i;
614 	int err;
615 
616 	err = kstrtouint(buf, 10, &i);
617 	if (err)
618 		return err;
619 
620 	if (i)
621 		ads7846_disable(ts);
622 	else
623 		ads7846_enable(ts);
624 
625 	return count;
626 }
627 
628 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
629 
630 static struct attribute *ads784x_attributes[] = {
631 	&dev_attr_pen_down.attr,
632 	&dev_attr_disable.attr,
633 	NULL,
634 };
635 
636 static const struct attribute_group ads784x_attr_group = {
637 	.attrs = ads784x_attributes,
638 };
639 
640 /*--------------------------------------------------------------------------*/
641 
642 static void null_wait_for_sync(void)
643 {
644 }
645 
646 static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
647 {
648 	struct ads7846 *ts = ads;
649 
650 	if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
651 		/* Start over collecting consistent readings. */
652 		ts->read_rep = 0;
653 		/*
654 		 * Repeat it, if this was the first read or the read
655 		 * wasn't consistent enough.
656 		 */
657 		if (ts->read_cnt < ts->debounce_max) {
658 			ts->last_read = *val;
659 			ts->read_cnt++;
660 			return ADS7846_FILTER_REPEAT;
661 		} else {
662 			/*
663 			 * Maximum number of debouncing reached and still
664 			 * not enough number of consistent readings. Abort
665 			 * the whole sample, repeat it in the next sampling
666 			 * period.
667 			 */
668 			ts->read_cnt = 0;
669 			return ADS7846_FILTER_IGNORE;
670 		}
671 	} else {
672 		if (++ts->read_rep > ts->debounce_rep) {
673 			/*
674 			 * Got a good reading for this coordinate,
675 			 * go for the next one.
676 			 */
677 			ts->read_cnt = 0;
678 			ts->read_rep = 0;
679 			return ADS7846_FILTER_OK;
680 		} else {
681 			/* Read more values that are consistent. */
682 			ts->read_cnt++;
683 			return ADS7846_FILTER_REPEAT;
684 		}
685 	}
686 }
687 
688 static int ads7846_no_filter(void *ads, int data_idx, int *val)
689 {
690 	return ADS7846_FILTER_OK;
691 }
692 
693 static int ads7846_get_value(struct ads7846_buf *buf)
694 {
695 	int value;
696 
697 	value = be16_to_cpup(&buf->data);
698 
699 	/* enforce ADC output is 12 bits width */
700 	return (value >> 3) & 0xfff;
701 }
702 
703 static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx,
704 				u16 val)
705 {
706 	struct ads7846_packet *packet = ts->packet;
707 
708 	switch (cmd_idx) {
709 	case ADS7846_Y:
710 		packet->y = val;
711 		break;
712 	case ADS7846_X:
713 		packet->x = val;
714 		break;
715 	case ADS7846_Z1:
716 		packet->z1 = val;
717 		break;
718 	case ADS7846_Z2:
719 		packet->z2 = val;
720 		break;
721 	default:
722 		WARN_ON_ONCE(1);
723 	}
724 }
725 
726 static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref)
727 {
728 	switch (cmd_idx) {
729 	case ADS7846_Y:
730 		return READ_Y(vref);
731 	case ADS7846_X:
732 		return READ_X(vref);
733 
734 	/* 7846 specific commands  */
735 	case ADS7846_Z1:
736 		return READ_Z1(vref);
737 	case ADS7846_Z2:
738 		return READ_Z2(vref);
739 	case ADS7846_PWDOWN:
740 		return PWRDOWN;
741 	default:
742 		WARN_ON_ONCE(1);
743 	}
744 
745 	return 0;
746 }
747 
748 static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx)
749 {
750 	switch (cmd_idx) {
751 	case ADS7846_X:
752 	case ADS7846_Y:
753 	case ADS7846_Z1:
754 	case ADS7846_Z2:
755 		return true;
756 	case ADS7846_PWDOWN:
757 		return false;
758 	default:
759 		WARN_ON_ONCE(1);
760 	}
761 
762 	return false;
763 }
764 
765 static int ads7846_filter(struct ads7846 *ts)
766 {
767 	struct ads7846_packet *packet = ts->packet;
768 	int action;
769 	int val;
770 	unsigned int cmd_idx, b;
771 
772 	packet->ignore = false;
773 	for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) {
774 		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
775 
776 		packet->last_cmd_idx = cmd_idx;
777 
778 		for (b = l->skip; b < l->count; b++) {
779 			val = ads7846_get_value(&packet->rx[l->offset + b]);
780 
781 			action = ts->filter(ts->filter_data, cmd_idx, &val);
782 			if (action == ADS7846_FILTER_REPEAT) {
783 				if (b == l->count - 1)
784 					return -EAGAIN;
785 			} else if (action == ADS7846_FILTER_OK) {
786 				ads7846_set_cmd_val(ts, cmd_idx, val);
787 				break;
788 			} else {
789 				packet->ignore = true;
790 				return 0;
791 			}
792 		}
793 	}
794 
795 	return 0;
796 }
797 
798 static void ads7846_read_state(struct ads7846 *ts)
799 {
800 	struct ads7846_packet *packet = ts->packet;
801 	struct spi_message *m;
802 	int msg_idx = 0;
803 	int error;
804 
805 	packet->last_cmd_idx = 0;
806 
807 	while (true) {
808 		ts->wait_for_sync();
809 
810 		m = &ts->msg[msg_idx];
811 		error = spi_sync(ts->spi, m);
812 		if (error) {
813 			dev_err(&ts->spi->dev, "spi_sync --> %d\n", error);
814 			packet->ignore = true;
815 			return;
816 		}
817 
818 		error = ads7846_filter(ts);
819 		if (error)
820 			continue;
821 
822 		return;
823 	}
824 }
825 
826 static void ads7846_report_state(struct ads7846 *ts)
827 {
828 	struct ads7846_packet *packet = ts->packet;
829 	unsigned int Rt;
830 	u16 x, y, z1, z2;
831 
832 	x = packet->x;
833 	y = packet->y;
834 	if (ts->model == 7845) {
835 		z1 = 0;
836 		z2 = 0;
837 	} else {
838 		z1 = packet->z1;
839 		z2 = packet->z2;
840 	}
841 
842 	/* range filtering */
843 	if (x == MAX_12BIT)
844 		x = 0;
845 
846 	if (ts->model == 7843 || ts->model == 7845) {
847 		Rt = ts->pressure_max / 2;
848 	} else if (likely(x && z1)) {
849 		/* compute touch pressure resistance using equation #2 */
850 		Rt = z2;
851 		Rt -= z1;
852 		Rt *= ts->x_plate_ohms;
853 		Rt = DIV_ROUND_CLOSEST(Rt, 16);
854 		Rt *= x;
855 		Rt /= z1;
856 		Rt = DIV_ROUND_CLOSEST(Rt, 256);
857 	} else {
858 		Rt = 0;
859 	}
860 
861 	/*
862 	 * Sample found inconsistent by debouncing or pressure is beyond
863 	 * the maximum. Don't report it to user space, repeat at least
864 	 * once more the measurement
865 	 */
866 	if (packet->ignore || Rt > ts->pressure_max) {
867 		dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
868 			 packet->ignore, Rt);
869 		return;
870 	}
871 
872 	/*
873 	 * Maybe check the pendown state before reporting. This discards
874 	 * false readings when the pen is lifted.
875 	 */
876 	if (ts->penirq_recheck_delay_usecs) {
877 		udelay(ts->penirq_recheck_delay_usecs);
878 		if (!get_pendown_state(ts))
879 			Rt = 0;
880 	}
881 
882 	/*
883 	 * NOTE: We can't rely on the pressure to determine the pen down
884 	 * state, even this controller has a pressure sensor. The pressure
885 	 * value can fluctuate for quite a while after lifting the pen and
886 	 * in some cases may not even settle at the expected value.
887 	 *
888 	 * The only safe way to check for the pen up condition is in the
889 	 * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
890 	 */
891 	if (Rt) {
892 		struct input_dev *input = ts->input;
893 
894 		if (!ts->pendown) {
895 			input_report_key(input, BTN_TOUCH, 1);
896 			ts->pendown = true;
897 			dev_vdbg(&ts->spi->dev, "DOWN\n");
898 		}
899 
900 		touchscreen_report_pos(input, &ts->core_prop, x, y, false);
901 		input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
902 
903 		input_sync(input);
904 		dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
905 	}
906 }
907 
908 static irqreturn_t ads7846_hard_irq(int irq, void *handle)
909 {
910 	struct ads7846 *ts = handle;
911 
912 	return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
913 }
914 
915 
916 static irqreturn_t ads7846_irq(int irq, void *handle)
917 {
918 	struct ads7846 *ts = handle;
919 
920 	/* Start with a small delay before checking pendown state */
921 	msleep(TS_POLL_DELAY);
922 
923 	while (!ts->stopped && get_pendown_state(ts)) {
924 
925 		/* pen is down, continue with the measurement */
926 		ads7846_read_state(ts);
927 
928 		if (!ts->stopped)
929 			ads7846_report_state(ts);
930 
931 		wait_event_timeout(ts->wait, ts->stopped,
932 				   msecs_to_jiffies(TS_POLL_PERIOD));
933 	}
934 
935 	if (ts->pendown && !ts->stopped)
936 		ads7846_report_pen_up(ts);
937 
938 	return IRQ_HANDLED;
939 }
940 
941 static int ads7846_suspend(struct device *dev)
942 {
943 	struct ads7846 *ts = dev_get_drvdata(dev);
944 
945 	mutex_lock(&ts->lock);
946 
947 	if (!ts->suspended) {
948 
949 		if (!ts->disabled)
950 			__ads7846_disable(ts);
951 
952 		if (device_may_wakeup(&ts->spi->dev))
953 			enable_irq_wake(ts->spi->irq);
954 
955 		ts->suspended = true;
956 	}
957 
958 	mutex_unlock(&ts->lock);
959 
960 	return 0;
961 }
962 
963 static int ads7846_resume(struct device *dev)
964 {
965 	struct ads7846 *ts = dev_get_drvdata(dev);
966 
967 	mutex_lock(&ts->lock);
968 
969 	if (ts->suspended) {
970 
971 		ts->suspended = false;
972 
973 		if (device_may_wakeup(&ts->spi->dev))
974 			disable_irq_wake(ts->spi->irq);
975 
976 		if (!ts->disabled)
977 			__ads7846_enable(ts);
978 	}
979 
980 	mutex_unlock(&ts->lock);
981 
982 	return 0;
983 }
984 
985 static DEFINE_SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
986 
987 static int ads7846_setup_pendown(struct spi_device *spi,
988 				 struct ads7846 *ts,
989 				 const struct ads7846_platform_data *pdata)
990 {
991 	int err;
992 
993 	/*
994 	 * REVISIT when the irq can be triggered active-low, or if for some
995 	 * reason the touchscreen isn't hooked up, we don't need to access
996 	 * the pendown state.
997 	 */
998 
999 	if (pdata->get_pendown_state) {
1000 		ts->get_pendown_state = pdata->get_pendown_state;
1001 	} else if (gpio_is_valid(pdata->gpio_pendown)) {
1002 
1003 		err = devm_gpio_request_one(&spi->dev, pdata->gpio_pendown,
1004 					    GPIOF_IN, "ads7846_pendown");
1005 		if (err) {
1006 			dev_err(&spi->dev,
1007 				"failed to request/setup pendown GPIO%d: %d\n",
1008 				pdata->gpio_pendown, err);
1009 			return err;
1010 		}
1011 
1012 		ts->gpio_pendown = pdata->gpio_pendown;
1013 
1014 		if (pdata->gpio_pendown_debounce)
1015 			gpio_set_debounce(pdata->gpio_pendown,
1016 					  pdata->gpio_pendown_debounce);
1017 	} else {
1018 		dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
1019 		return -EINVAL;
1020 	}
1021 
1022 	return 0;
1023 }
1024 
1025 /*
1026  * Set up the transfers to read touchscreen state; this assumes we
1027  * use formula #2 for pressure, not #3.
1028  */
1029 static int ads7846_setup_spi_msg(struct ads7846 *ts,
1030 				  const struct ads7846_platform_data *pdata)
1031 {
1032 	struct spi_message *m = &ts->msg[0];
1033 	struct spi_transfer *x = ts->xfer;
1034 	struct ads7846_packet *packet = ts->packet;
1035 	int vref = pdata->keep_vref_on;
1036 	unsigned int count, offset = 0;
1037 	unsigned int cmd_idx, b;
1038 	unsigned long time;
1039 	size_t size = 0;
1040 
1041 	/* time per bit */
1042 	time = NSEC_PER_SEC / ts->spi->max_speed_hz;
1043 
1044 	count = pdata->settle_delay_usecs * NSEC_PER_USEC / time;
1045 	packet->count_skip = DIV_ROUND_UP(count, 24);
1046 
1047 	if (ts->debounce_max && ts->debounce_rep)
1048 		/* ads7846_debounce_filter() is making ts->debounce_rep + 2
1049 		 * reads. So we need to get all samples for normal case. */
1050 		packet->count = ts->debounce_rep + 2;
1051 	else
1052 		packet->count = 1;
1053 
1054 	if (ts->model == 7846)
1055 		packet->cmds = 5; /* x, y, z1, z2, pwdown */
1056 	else
1057 		packet->cmds = 3; /* x, y, pwdown */
1058 
1059 	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
1060 		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
1061 		unsigned int max_count;
1062 
1063 		if (cmd_idx == packet->cmds - 1)
1064 			cmd_idx = ADS7846_PWDOWN;
1065 
1066 		if (ads7846_cmd_need_settle(cmd_idx))
1067 			max_count = packet->count + packet->count_skip;
1068 		else
1069 			max_count = packet->count;
1070 
1071 		l->offset = offset;
1072 		offset += max_count;
1073 		l->count = max_count;
1074 		l->skip = packet->count_skip;
1075 		size += sizeof(*packet->tx) * max_count;
1076 	}
1077 
1078 	packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
1079 	if (!packet->tx)
1080 		return -ENOMEM;
1081 
1082 	packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
1083 	if (!packet->rx)
1084 		return -ENOMEM;
1085 
1086 	if (ts->model == 7873) {
1087 		/*
1088 		 * The AD7873 is almost identical to the ADS7846
1089 		 * keep VREF off during differential/ratiometric
1090 		 * conversion modes.
1091 		 */
1092 		ts->model = 7846;
1093 		vref = 0;
1094 	}
1095 
1096 	ts->msg_count = 1;
1097 	spi_message_init(m);
1098 	m->context = ts;
1099 
1100 	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
1101 		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
1102 		u8 cmd;
1103 
1104 		if (cmd_idx == packet->cmds - 1)
1105 			cmd_idx = ADS7846_PWDOWN;
1106 
1107 		cmd = ads7846_get_cmd(cmd_idx, vref);
1108 
1109 		for (b = 0; b < l->count; b++)
1110 			packet->tx[l->offset + b].cmd = cmd;
1111 	}
1112 
1113 	x->tx_buf = packet->tx;
1114 	x->rx_buf = packet->rx;
1115 	x->len = size;
1116 	spi_message_add_tail(x, m);
1117 
1118 	return 0;
1119 }
1120 
1121 #ifdef CONFIG_OF
1122 static const struct of_device_id ads7846_dt_ids[] = {
1123 	{ .compatible = "ti,tsc2046",	.data = (void *) 7846 },
1124 	{ .compatible = "ti,ads7843",	.data = (void *) 7843 },
1125 	{ .compatible = "ti,ads7845",	.data = (void *) 7845 },
1126 	{ .compatible = "ti,ads7846",	.data = (void *) 7846 },
1127 	{ .compatible = "ti,ads7873",	.data = (void *) 7873 },
1128 	{ }
1129 };
1130 MODULE_DEVICE_TABLE(of, ads7846_dt_ids);
1131 
1132 static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev)
1133 {
1134 	struct ads7846_platform_data *pdata;
1135 	struct device_node *node = dev->of_node;
1136 	const struct of_device_id *match;
1137 	u32 value;
1138 
1139 	if (!node) {
1140 		dev_err(dev, "Device does not have associated DT data\n");
1141 		return ERR_PTR(-EINVAL);
1142 	}
1143 
1144 	match = of_match_device(ads7846_dt_ids, dev);
1145 	if (!match) {
1146 		dev_err(dev, "Unknown device model\n");
1147 		return ERR_PTR(-EINVAL);
1148 	}
1149 
1150 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
1151 	if (!pdata)
1152 		return ERR_PTR(-ENOMEM);
1153 
1154 	pdata->model = (unsigned long)match->data;
1155 
1156 	of_property_read_u16(node, "ti,vref-delay-usecs",
1157 			     &pdata->vref_delay_usecs);
1158 	of_property_read_u16(node, "ti,vref-mv", &pdata->vref_mv);
1159 	pdata->keep_vref_on = of_property_read_bool(node, "ti,keep-vref-on");
1160 
1161 	pdata->swap_xy = of_property_read_bool(node, "ti,swap-xy");
1162 
1163 	of_property_read_u16(node, "ti,settle-delay-usec",
1164 			     &pdata->settle_delay_usecs);
1165 	of_property_read_u16(node, "ti,penirq-recheck-delay-usecs",
1166 			     &pdata->penirq_recheck_delay_usecs);
1167 
1168 	of_property_read_u16(node, "ti,x-plate-ohms", &pdata->x_plate_ohms);
1169 	of_property_read_u16(node, "ti,y-plate-ohms", &pdata->y_plate_ohms);
1170 
1171 	of_property_read_u16(node, "ti,x-min", &pdata->x_min);
1172 	of_property_read_u16(node, "ti,y-min", &pdata->y_min);
1173 	of_property_read_u16(node, "ti,x-max", &pdata->x_max);
1174 	of_property_read_u16(node, "ti,y-max", &pdata->y_max);
1175 
1176 	/*
1177 	 * touchscreen-max-pressure gets parsed during
1178 	 * touchscreen_parse_properties()
1179 	 */
1180 	of_property_read_u16(node, "ti,pressure-min", &pdata->pressure_min);
1181 	if (!of_property_read_u32(node, "touchscreen-min-pressure", &value))
1182 		pdata->pressure_min = (u16) value;
1183 	of_property_read_u16(node, "ti,pressure-max", &pdata->pressure_max);
1184 
1185 	of_property_read_u16(node, "ti,debounce-max", &pdata->debounce_max);
1186 	if (!of_property_read_u32(node, "touchscreen-average-samples", &value))
1187 		pdata->debounce_max = (u16) value;
1188 	of_property_read_u16(node, "ti,debounce-tol", &pdata->debounce_tol);
1189 	of_property_read_u16(node, "ti,debounce-rep", &pdata->debounce_rep);
1190 
1191 	of_property_read_u32(node, "ti,pendown-gpio-debounce",
1192 			     &pdata->gpio_pendown_debounce);
1193 
1194 	pdata->wakeup = of_property_read_bool(node, "wakeup-source") ||
1195 			of_property_read_bool(node, "linux,wakeup");
1196 
1197 	pdata->gpio_pendown = of_get_named_gpio(dev->of_node, "pendown-gpio", 0);
1198 
1199 	return pdata;
1200 }
1201 #else
1202 static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev)
1203 {
1204 	dev_err(dev, "no platform data defined\n");
1205 	return ERR_PTR(-EINVAL);
1206 }
1207 #endif
1208 
1209 static void ads7846_regulator_disable(void *regulator)
1210 {
1211 	regulator_disable(regulator);
1212 }
1213 
1214 static int ads7846_probe(struct spi_device *spi)
1215 {
1216 	const struct ads7846_platform_data *pdata;
1217 	struct ads7846 *ts;
1218 	struct device *dev = &spi->dev;
1219 	struct ads7846_packet *packet;
1220 	struct input_dev *input_dev;
1221 	unsigned long irq_flags;
1222 	int err;
1223 
1224 	if (!spi->irq) {
1225 		dev_dbg(dev, "no IRQ?\n");
1226 		return -EINVAL;
1227 	}
1228 
1229 	/* don't exceed max specified sample rate */
1230 	if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
1231 		dev_err(dev, "f(sample) %d KHz?\n",
1232 			(spi->max_speed_hz/SAMPLE_BITS)/1000);
1233 		return -EINVAL;
1234 	}
1235 
1236 	/*
1237 	 * We'd set TX word size 8 bits and RX word size to 13 bits ... except
1238 	 * that even if the hardware can do that, the SPI controller driver
1239 	 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
1240 	 */
1241 	spi->bits_per_word = 8;
1242 	spi->mode &= ~SPI_MODE_X_MASK;
1243 	spi->mode |= SPI_MODE_0;
1244 	err = spi_setup(spi);
1245 	if (err < 0)
1246 		return err;
1247 
1248 	ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL);
1249 	if (!ts)
1250 		return -ENOMEM;
1251 
1252 	packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL);
1253 	if (!packet)
1254 		return -ENOMEM;
1255 
1256 	input_dev = devm_input_allocate_device(dev);
1257 	if (!input_dev)
1258 		return -ENOMEM;
1259 
1260 	spi_set_drvdata(spi, ts);
1261 
1262 	ts->packet = packet;
1263 	ts->spi = spi;
1264 	ts->input = input_dev;
1265 
1266 	mutex_init(&ts->lock);
1267 	init_waitqueue_head(&ts->wait);
1268 
1269 	pdata = dev_get_platdata(dev);
1270 	if (!pdata) {
1271 		pdata = ads7846_probe_dt(dev);
1272 		if (IS_ERR(pdata))
1273 			return PTR_ERR(pdata);
1274 	}
1275 
1276 	ts->model = pdata->model ? : 7846;
1277 	ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
1278 	ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
1279 	ts->vref_mv = pdata->vref_mv;
1280 
1281 	if (pdata->debounce_max) {
1282 		ts->debounce_max = pdata->debounce_max;
1283 		if (ts->debounce_max < 2)
1284 			ts->debounce_max = 2;
1285 		ts->debounce_tol = pdata->debounce_tol;
1286 		ts->debounce_rep = pdata->debounce_rep;
1287 		ts->filter = ads7846_debounce_filter;
1288 		ts->filter_data = ts;
1289 	} else {
1290 		ts->filter = ads7846_no_filter;
1291 	}
1292 
1293 	err = ads7846_setup_pendown(spi, ts, pdata);
1294 	if (err)
1295 		return err;
1296 
1297 	if (pdata->penirq_recheck_delay_usecs)
1298 		ts->penirq_recheck_delay_usecs =
1299 				pdata->penirq_recheck_delay_usecs;
1300 
1301 	ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
1302 
1303 	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
1304 	snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
1305 
1306 	input_dev->name = ts->name;
1307 	input_dev->phys = ts->phys;
1308 
1309 	input_dev->id.bustype = BUS_SPI;
1310 	input_dev->id.product = pdata->model;
1311 
1312 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
1313 	input_set_abs_params(input_dev, ABS_X,
1314 			pdata->x_min ? : 0,
1315 			pdata->x_max ? : MAX_12BIT,
1316 			0, 0);
1317 	input_set_abs_params(input_dev, ABS_Y,
1318 			pdata->y_min ? : 0,
1319 			pdata->y_max ? : MAX_12BIT,
1320 			0, 0);
1321 	if (ts->model != 7845)
1322 		input_set_abs_params(input_dev, ABS_PRESSURE,
1323 				pdata->pressure_min, pdata->pressure_max, 0, 0);
1324 
1325 	/*
1326 	 * Parse common framework properties. Must be done here to ensure the
1327 	 * correct behaviour in case of using the legacy vendor bindings. The
1328 	 * general binding value overrides the vendor specific one.
1329 	 */
1330 	touchscreen_parse_properties(ts->input, false, &ts->core_prop);
1331 	ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0;
1332 
1333 	/*
1334 	 * Check if legacy ti,swap-xy binding is used instead of
1335 	 * touchscreen-swapped-x-y
1336 	 */
1337 	if (!ts->core_prop.swap_x_y && pdata->swap_xy) {
1338 		swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]);
1339 		ts->core_prop.swap_x_y = true;
1340 	}
1341 
1342 	ads7846_setup_spi_msg(ts, pdata);
1343 
1344 	ts->reg = devm_regulator_get(dev, "vcc");
1345 	if (IS_ERR(ts->reg)) {
1346 		err = PTR_ERR(ts->reg);
1347 		dev_err(dev, "unable to get regulator: %d\n", err);
1348 		return err;
1349 	}
1350 
1351 	err = regulator_enable(ts->reg);
1352 	if (err) {
1353 		dev_err(dev, "unable to enable regulator: %d\n", err);
1354 		return err;
1355 	}
1356 
1357 	err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg);
1358 	if (err)
1359 		return err;
1360 
1361 	irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
1362 	irq_flags |= IRQF_ONESHOT;
1363 
1364 	err = devm_request_threaded_irq(dev, spi->irq,
1365 					ads7846_hard_irq, ads7846_irq,
1366 					irq_flags, dev->driver->name, ts);
1367 	if (err && err != -EPROBE_DEFER && !pdata->irq_flags) {
1368 		dev_info(dev,
1369 			"trying pin change workaround on irq %d\n", spi->irq);
1370 		irq_flags |= IRQF_TRIGGER_RISING;
1371 		err = devm_request_threaded_irq(dev, spi->irq,
1372 						ads7846_hard_irq, ads7846_irq,
1373 						irq_flags, dev->driver->name,
1374 						ts);
1375 	}
1376 
1377 	if (err) {
1378 		dev_dbg(dev, "irq %d busy?\n", spi->irq);
1379 		return err;
1380 	}
1381 
1382 	err = ads784x_hwmon_register(spi, ts);
1383 	if (err)
1384 		return err;
1385 
1386 	dev_info(dev, "touchscreen, irq %d\n", spi->irq);
1387 
1388 	/*
1389 	 * Take a first sample, leaving nPENIRQ active and vREF off; avoid
1390 	 * the touchscreen, in case it's not connected.
1391 	 */
1392 	if (ts->model == 7845)
1393 		ads7845_read12_ser(dev, PWRDOWN);
1394 	else
1395 		(void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux));
1396 
1397 	err = devm_device_add_group(dev, &ads784x_attr_group);
1398 	if (err)
1399 		return err;
1400 
1401 	err = input_register_device(input_dev);
1402 	if (err)
1403 		return err;
1404 
1405 	device_init_wakeup(dev, pdata->wakeup);
1406 
1407 	/*
1408 	 * If device does not carry platform data we must have allocated it
1409 	 * when parsing DT data.
1410 	 */
1411 	if (!dev_get_platdata(dev))
1412 		devm_kfree(dev, (void *)pdata);
1413 
1414 	return 0;
1415 }
1416 
1417 static void ads7846_remove(struct spi_device *spi)
1418 {
1419 	struct ads7846 *ts = spi_get_drvdata(spi);
1420 
1421 	ads7846_stop(ts);
1422 }
1423 
1424 static struct spi_driver ads7846_driver = {
1425 	.driver = {
1426 		.name	= "ads7846",
1427 		.pm	= pm_sleep_ptr(&ads7846_pm),
1428 		.of_match_table = of_match_ptr(ads7846_dt_ids),
1429 	},
1430 	.probe		= ads7846_probe,
1431 	.remove		= ads7846_remove,
1432 };
1433 
1434 module_spi_driver(ads7846_driver);
1435 
1436 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1437 MODULE_LICENSE("GPL");
1438 MODULE_ALIAS("spi:ads7846");
1439