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/property.h>
28 #include <linux/gpio/consumer.h>
29 #include <linux/spi/spi.h>
30 #include <linux/spi/ads7846.h>
31 #include <linux/regulator/consumer.h>
32 #include <linux/module.h>
33 #include <asm/unaligned.h>
34 
35 /*
36  * This code has been heavily tested on a Nokia 770, and lightly
37  * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
38  * TSC2046 is just newer ads7846 silicon.
39  * Support for ads7843 tested on Atmel at91sam926x-EK.
40  * Support for ads7845 has only been stubbed in.
41  * Support for Analog Devices AD7873 and AD7843 tested.
42  *
43  * IRQ handling needs a workaround because of a shortcoming in handling
44  * edge triggered IRQs on some platforms like the OMAP1/2. These
45  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
46  * have to maintain our own SW IRQ disabled status. This should be
47  * removed as soon as the affected platform's IRQ handling is fixed.
48  *
49  * App note sbaa036 talks in more detail about accurate sampling...
50  * that ought to help in situations like LCDs inducing noise (which
51  * can also be helped by using synch signals) and more generally.
52  * This driver tries to utilize the measures described in the app
53  * note. The strength of filtering can be set in the board-* specific
54  * files.
55  */
56 
57 #define TS_POLL_DELAY	1	/* ms delay before the first sample */
58 #define TS_POLL_PERIOD	5	/* ms delay between samples */
59 
60 /* this driver doesn't aim at the peak continuous sample rate */
61 #define	SAMPLE_BITS	(8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
62 
63 struct ads7846_buf {
64 	u8 cmd;
65 	__be16 data;
66 } __packed;
67 
68 struct ads7846_buf_layout {
69 	unsigned int offset;
70 	unsigned int count;
71 	unsigned int skip;
72 };
73 
74 /*
75  * We allocate this separately to avoid cache line sharing issues when
76  * driver is used with DMA-based SPI controllers (like atmel_spi) on
77  * systems where main memory is not DMA-coherent (most non-x86 boards).
78  */
79 struct ads7846_packet {
80 	unsigned int count;
81 	unsigned int count_skip;
82 	unsigned int cmds;
83 	unsigned int last_cmd_idx;
84 	struct ads7846_buf_layout l[5];
85 	struct ads7846_buf *rx;
86 	struct ads7846_buf *tx;
87 
88 	struct ads7846_buf pwrdown_cmd;
89 
90 	bool ignore;
91 	u16 x, y, z1, z2;
92 };
93 
94 struct ads7846 {
95 	struct input_dev	*input;
96 	char			phys[32];
97 	char			name[32];
98 
99 	struct spi_device	*spi;
100 	struct regulator	*reg;
101 
102 	u16			model;
103 	u16			vref_mv;
104 	u16			vref_delay_usecs;
105 	u16			x_plate_ohms;
106 	u16			pressure_max;
107 
108 	bool			swap_xy;
109 	bool			use_internal;
110 
111 	struct ads7846_packet	*packet;
112 
113 	struct spi_transfer	xfer[18];
114 	struct spi_message	msg[5];
115 	int			msg_count;
116 	wait_queue_head_t	wait;
117 
118 	bool			pendown;
119 
120 	int			read_cnt;
121 	int			read_rep;
122 	int			last_read;
123 
124 	u16			debounce_max;
125 	u16			debounce_tol;
126 	u16			debounce_rep;
127 
128 	u16			penirq_recheck_delay_usecs;
129 
130 	struct touchscreen_properties core_prop;
131 
132 	struct mutex		lock;
133 	bool			stopped;	/* P: lock */
134 	bool			disabled;	/* P: lock */
135 	bool			suspended;	/* P: lock */
136 
137 	int			(*filter)(void *data, int data_idx, int *val);
138 	void			*filter_data;
139 	int			(*get_pendown_state)(void);
140 	struct gpio_desc	*gpio_pendown;
141 
142 	void			(*wait_for_sync)(void);
143 };
144 
145 enum ads7846_filter {
146 	ADS7846_FILTER_OK,
147 	ADS7846_FILTER_REPEAT,
148 	ADS7846_FILTER_IGNORE,
149 };
150 
151 /* leave chip selected when we're done, for quicker re-select? */
152 #if	0
153 #define	CS_CHANGE(xfer)	((xfer).cs_change = 1)
154 #else
155 #define	CS_CHANGE(xfer)	((xfer).cs_change = 0)
156 #endif
157 
158 /*--------------------------------------------------------------------------*/
159 
160 /* The ADS7846 has touchscreen and other sensors.
161  * Earlier ads784x chips are somewhat compatible.
162  */
163 #define	ADS_START		(1 << 7)
164 #define	ADS_A2A1A0_d_y		(1 << 4)	/* differential */
165 #define	ADS_A2A1A0_d_z1		(3 << 4)	/* differential */
166 #define	ADS_A2A1A0_d_z2		(4 << 4)	/* differential */
167 #define	ADS_A2A1A0_d_x		(5 << 4)	/* differential */
168 #define	ADS_A2A1A0_temp0	(0 << 4)	/* non-differential */
169 #define	ADS_A2A1A0_vbatt	(2 << 4)	/* non-differential */
170 #define	ADS_A2A1A0_vaux		(6 << 4)	/* non-differential */
171 #define	ADS_A2A1A0_temp1	(7 << 4)	/* non-differential */
172 #define	ADS_8_BIT		(1 << 3)
173 #define	ADS_12_BIT		(0 << 3)
174 #define	ADS_SER			(1 << 2)	/* non-differential */
175 #define	ADS_DFR			(0 << 2)	/* differential */
176 #define	ADS_PD10_PDOWN		(0 << 0)	/* low power mode + penirq */
177 #define	ADS_PD10_ADC_ON		(1 << 0)	/* ADC on */
178 #define	ADS_PD10_REF_ON		(2 << 0)	/* vREF on + penirq */
179 #define	ADS_PD10_ALL_ON		(3 << 0)	/* ADC + vREF on */
180 
181 #define	MAX_12BIT	((1<<12)-1)
182 
183 /* leave ADC powered up (disables penirq) between differential samples */
184 #define	READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
185 	| ADS_12_BIT | ADS_DFR | \
186 	(adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
187 
188 #define	READ_Y(vref)	(READ_12BIT_DFR(y,  1, vref))
189 #define	READ_Z1(vref)	(READ_12BIT_DFR(z1, 1, vref))
190 #define	READ_Z2(vref)	(READ_12BIT_DFR(z2, 1, vref))
191 #define	READ_X(vref)	(READ_12BIT_DFR(x,  1, vref))
192 #define	PWRDOWN		(READ_12BIT_DFR(y,  0, 0))	/* LAST */
193 
194 /* single-ended samples need to first power up reference voltage;
195  * we leave both ADC and VREF powered
196  */
197 #define	READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
198 	| ADS_12_BIT | ADS_SER)
199 
200 #define	REF_ON	(READ_12BIT_DFR(x, 1, 1))
201 #define	REF_OFF	(READ_12BIT_DFR(y, 0, 0))
202 
203 /* Order commands in the most optimal way to reduce Vref switching and
204  * settling time:
205  * Measure:  X; Vref: X+, X-; IN: Y+
206  * Measure:  Y; Vref: Y+, Y-; IN: X+
207  * Measure: Z1; Vref: Y+, X-; IN: X+
208  * Measure: Z2; Vref: Y+, X-; IN: Y-
209  */
210 enum ads7846_cmds {
211 	ADS7846_X,
212 	ADS7846_Y,
213 	ADS7846_Z1,
214 	ADS7846_Z2,
215 	ADS7846_PWDOWN,
216 };
217 
218 static int get_pendown_state(struct ads7846 *ts)
219 {
220 	if (ts->get_pendown_state)
221 		return ts->get_pendown_state();
222 
223 	return gpiod_get_value(ts->gpio_pendown);
224 }
225 
226 static void ads7846_report_pen_up(struct ads7846 *ts)
227 {
228 	struct input_dev *input = ts->input;
229 
230 	input_report_key(input, BTN_TOUCH, 0);
231 	input_report_abs(input, ABS_PRESSURE, 0);
232 	input_sync(input);
233 
234 	ts->pendown = false;
235 	dev_vdbg(&ts->spi->dev, "UP\n");
236 }
237 
238 /* Must be called with ts->lock held */
239 static void ads7846_stop(struct ads7846 *ts)
240 {
241 	if (!ts->disabled && !ts->suspended) {
242 		/* Signal IRQ thread to stop polling and disable the handler. */
243 		ts->stopped = true;
244 		mb();
245 		wake_up(&ts->wait);
246 		disable_irq(ts->spi->irq);
247 	}
248 }
249 
250 /* Must be called with ts->lock held */
251 static void ads7846_restart(struct ads7846 *ts)
252 {
253 	if (!ts->disabled && !ts->suspended) {
254 		/* Check if pen was released since last stop */
255 		if (ts->pendown && !get_pendown_state(ts))
256 			ads7846_report_pen_up(ts);
257 
258 		/* Tell IRQ thread that it may poll the device. */
259 		ts->stopped = false;
260 		mb();
261 		enable_irq(ts->spi->irq);
262 	}
263 }
264 
265 /* Must be called with ts->lock held */
266 static void __ads7846_disable(struct ads7846 *ts)
267 {
268 	ads7846_stop(ts);
269 	regulator_disable(ts->reg);
270 
271 	/*
272 	 * We know the chip's in low power mode since we always
273 	 * leave it that way after every request
274 	 */
275 }
276 
277 /* Must be called with ts->lock held */
278 static void __ads7846_enable(struct ads7846 *ts)
279 {
280 	int error;
281 
282 	error = regulator_enable(ts->reg);
283 	if (error != 0)
284 		dev_err(&ts->spi->dev, "Failed to enable supply: %d\n", error);
285 
286 	ads7846_restart(ts);
287 }
288 
289 static void ads7846_disable(struct ads7846 *ts)
290 {
291 	mutex_lock(&ts->lock);
292 
293 	if (!ts->disabled) {
294 
295 		if  (!ts->suspended)
296 			__ads7846_disable(ts);
297 
298 		ts->disabled = true;
299 	}
300 
301 	mutex_unlock(&ts->lock);
302 }
303 
304 static void ads7846_enable(struct ads7846 *ts)
305 {
306 	mutex_lock(&ts->lock);
307 
308 	if (ts->disabled) {
309 
310 		ts->disabled = false;
311 
312 		if (!ts->suspended)
313 			__ads7846_enable(ts);
314 	}
315 
316 	mutex_unlock(&ts->lock);
317 }
318 
319 /*--------------------------------------------------------------------------*/
320 
321 /*
322  * Non-touchscreen sensors only use single-ended conversions.
323  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
324  * ads7846 lets that pin be unconnected, to use internal vREF.
325  */
326 
327 struct ser_req {
328 	u8			ref_on;
329 	u8			command;
330 	u8			ref_off;
331 	u16			scratch;
332 	struct spi_message	msg;
333 	struct spi_transfer	xfer[6];
334 	/*
335 	 * DMA (thus cache coherency maintenance) requires the
336 	 * transfer buffers to live in their own cache lines.
337 	 */
338 	__be16 sample ____cacheline_aligned;
339 };
340 
341 struct ads7845_ser_req {
342 	u8			command[3];
343 	struct spi_message	msg;
344 	struct spi_transfer	xfer[2];
345 	/*
346 	 * DMA (thus cache coherency maintenance) requires the
347 	 * transfer buffers to live in their own cache lines.
348 	 */
349 	u8 sample[3] ____cacheline_aligned;
350 };
351 
352 static int ads7846_read12_ser(struct device *dev, unsigned command)
353 {
354 	struct spi_device *spi = to_spi_device(dev);
355 	struct ads7846 *ts = dev_get_drvdata(dev);
356 	struct ser_req *req;
357 	int status;
358 
359 	req = kzalloc(sizeof *req, GFP_KERNEL);
360 	if (!req)
361 		return -ENOMEM;
362 
363 	spi_message_init(&req->msg);
364 
365 	/* maybe turn on internal vREF, and let it settle */
366 	if (ts->use_internal) {
367 		req->ref_on = REF_ON;
368 		req->xfer[0].tx_buf = &req->ref_on;
369 		req->xfer[0].len = 1;
370 		spi_message_add_tail(&req->xfer[0], &req->msg);
371 
372 		req->xfer[1].rx_buf = &req->scratch;
373 		req->xfer[1].len = 2;
374 
375 		/* for 1uF, settle for 800 usec; no cap, 100 usec.  */
376 		req->xfer[1].delay.value = ts->vref_delay_usecs;
377 		req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS;
378 		spi_message_add_tail(&req->xfer[1], &req->msg);
379 
380 		/* Enable reference voltage */
381 		command |= ADS_PD10_REF_ON;
382 	}
383 
384 	/* Enable ADC in every case */
385 	command |= ADS_PD10_ADC_ON;
386 
387 	/* take sample */
388 	req->command = (u8) command;
389 	req->xfer[2].tx_buf = &req->command;
390 	req->xfer[2].len = 1;
391 	spi_message_add_tail(&req->xfer[2], &req->msg);
392 
393 	req->xfer[3].rx_buf = &req->sample;
394 	req->xfer[3].len = 2;
395 	spi_message_add_tail(&req->xfer[3], &req->msg);
396 
397 	/* REVISIT:  take a few more samples, and compare ... */
398 
399 	/* converter in low power mode & enable PENIRQ */
400 	req->ref_off = PWRDOWN;
401 	req->xfer[4].tx_buf = &req->ref_off;
402 	req->xfer[4].len = 1;
403 	spi_message_add_tail(&req->xfer[4], &req->msg);
404 
405 	req->xfer[5].rx_buf = &req->scratch;
406 	req->xfer[5].len = 2;
407 	CS_CHANGE(req->xfer[5]);
408 	spi_message_add_tail(&req->xfer[5], &req->msg);
409 
410 	mutex_lock(&ts->lock);
411 	ads7846_stop(ts);
412 	status = spi_sync(spi, &req->msg);
413 	ads7846_restart(ts);
414 	mutex_unlock(&ts->lock);
415 
416 	if (status == 0) {
417 		/* on-wire is a must-ignore bit, a BE12 value, then padding */
418 		status = be16_to_cpu(req->sample);
419 		status = status >> 3;
420 		status &= 0x0fff;
421 	}
422 
423 	kfree(req);
424 	return status;
425 }
426 
427 static int ads7845_read12_ser(struct device *dev, unsigned command)
428 {
429 	struct spi_device *spi = to_spi_device(dev);
430 	struct ads7846 *ts = dev_get_drvdata(dev);
431 	struct ads7845_ser_req *req;
432 	int status;
433 
434 	req = kzalloc(sizeof *req, GFP_KERNEL);
435 	if (!req)
436 		return -ENOMEM;
437 
438 	spi_message_init(&req->msg);
439 
440 	req->command[0] = (u8) command;
441 	req->xfer[0].tx_buf = req->command;
442 	req->xfer[0].rx_buf = req->sample;
443 	req->xfer[0].len = 3;
444 	spi_message_add_tail(&req->xfer[0], &req->msg);
445 
446 	mutex_lock(&ts->lock);
447 	ads7846_stop(ts);
448 	status = spi_sync(spi, &req->msg);
449 	ads7846_restart(ts);
450 	mutex_unlock(&ts->lock);
451 
452 	if (status == 0) {
453 		/* BE12 value, then padding */
454 		status = get_unaligned_be16(&req->sample[1]);
455 		status = status >> 3;
456 		status &= 0x0fff;
457 	}
458 
459 	kfree(req);
460 	return status;
461 }
462 
463 #if IS_ENABLED(CONFIG_HWMON)
464 
465 #define SHOW(name, var, adjust) static ssize_t \
466 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
467 { \
468 	struct ads7846 *ts = dev_get_drvdata(dev); \
469 	ssize_t v = ads7846_read12_ser(&ts->spi->dev, \
470 			READ_12BIT_SER(var)); \
471 	if (v < 0) \
472 		return v; \
473 	return sprintf(buf, "%u\n", adjust(ts, v)); \
474 } \
475 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
476 
477 
478 /* Sysfs conventions report temperatures in millidegrees Celsius.
479  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
480  * accuracy scheme without calibration data.  For now we won't try either;
481  * userspace sees raw sensor values, and must scale/calibrate appropriately.
482  */
483 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
484 {
485 	return v;
486 }
487 
488 SHOW(temp0, temp0, null_adjust)		/* temp1_input */
489 SHOW(temp1, temp1, null_adjust)		/* temp2_input */
490 
491 
492 /* sysfs conventions report voltages in millivolts.  We can convert voltages
493  * if we know vREF.  userspace may need to scale vAUX to match the board's
494  * external resistors; we assume that vBATT only uses the internal ones.
495  */
496 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
497 {
498 	unsigned retval = v;
499 
500 	/* external resistors may scale vAUX into 0..vREF */
501 	retval *= ts->vref_mv;
502 	retval = retval >> 12;
503 
504 	return retval;
505 }
506 
507 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
508 {
509 	unsigned retval = vaux_adjust(ts, v);
510 
511 	/* ads7846 has a resistor ladder to scale this signal down */
512 	if (ts->model == 7846)
513 		retval *= 4;
514 
515 	return retval;
516 }
517 
518 SHOW(in0_input, vaux, vaux_adjust)
519 SHOW(in1_input, vbatt, vbatt_adjust)
520 
521 static umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr,
522 				  int index)
523 {
524 	struct device *dev = kobj_to_dev(kobj);
525 	struct ads7846 *ts = dev_get_drvdata(dev);
526 
527 	if (ts->model == 7843 && index < 2)	/* in0, in1 */
528 		return 0;
529 	if (ts->model == 7845 && index != 2)	/* in0 */
530 		return 0;
531 
532 	return attr->mode;
533 }
534 
535 static struct attribute *ads7846_attributes[] = {
536 	&dev_attr_temp0.attr,		/* 0 */
537 	&dev_attr_temp1.attr,		/* 1 */
538 	&dev_attr_in0_input.attr,	/* 2 */
539 	&dev_attr_in1_input.attr,	/* 3 */
540 	NULL,
541 };
542 
543 static const struct attribute_group ads7846_attr_group = {
544 	.attrs = ads7846_attributes,
545 	.is_visible = ads7846_is_visible,
546 };
547 __ATTRIBUTE_GROUPS(ads7846_attr);
548 
549 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
550 {
551 	struct device *hwmon;
552 
553 	/* hwmon sensors need a reference voltage */
554 	switch (ts->model) {
555 	case 7846:
556 		if (!ts->vref_mv) {
557 			dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
558 			ts->vref_mv = 2500;
559 			ts->use_internal = true;
560 		}
561 		break;
562 	case 7845:
563 	case 7843:
564 		if (!ts->vref_mv) {
565 			dev_warn(&spi->dev,
566 				"external vREF for ADS%d not specified\n",
567 				ts->model);
568 			return 0;
569 		}
570 		break;
571 	}
572 
573 	hwmon = devm_hwmon_device_register_with_groups(&spi->dev,
574 						       spi->modalias, ts,
575 						       ads7846_attr_groups);
576 
577 	return PTR_ERR_OR_ZERO(hwmon);
578 }
579 
580 #else
581 static inline int ads784x_hwmon_register(struct spi_device *spi,
582 					 struct ads7846 *ts)
583 {
584 	return 0;
585 }
586 #endif
587 
588 static ssize_t ads7846_pen_down_show(struct device *dev,
589 				     struct device_attribute *attr, char *buf)
590 {
591 	struct ads7846 *ts = dev_get_drvdata(dev);
592 
593 	return sprintf(buf, "%u\n", ts->pendown);
594 }
595 
596 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
597 
598 static ssize_t ads7846_disable_show(struct device *dev,
599 				     struct device_attribute *attr, char *buf)
600 {
601 	struct ads7846 *ts = dev_get_drvdata(dev);
602 
603 	return sprintf(buf, "%u\n", ts->disabled);
604 }
605 
606 static ssize_t ads7846_disable_store(struct device *dev,
607 				     struct device_attribute *attr,
608 				     const char *buf, size_t count)
609 {
610 	struct ads7846 *ts = dev_get_drvdata(dev);
611 	unsigned int i;
612 	int err;
613 
614 	err = kstrtouint(buf, 10, &i);
615 	if (err)
616 		return err;
617 
618 	if (i)
619 		ads7846_disable(ts);
620 	else
621 		ads7846_enable(ts);
622 
623 	return count;
624 }
625 
626 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
627 
628 static struct attribute *ads784x_attributes[] = {
629 	&dev_attr_pen_down.attr,
630 	&dev_attr_disable.attr,
631 	NULL,
632 };
633 
634 static const struct attribute_group ads784x_attr_group = {
635 	.attrs = ads784x_attributes,
636 };
637 
638 /*--------------------------------------------------------------------------*/
639 
640 static void null_wait_for_sync(void)
641 {
642 }
643 
644 static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
645 {
646 	struct ads7846 *ts = ads;
647 
648 	if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
649 		/* Start over collecting consistent readings. */
650 		ts->read_rep = 0;
651 		/*
652 		 * Repeat it, if this was the first read or the read
653 		 * wasn't consistent enough.
654 		 */
655 		if (ts->read_cnt < ts->debounce_max) {
656 			ts->last_read = *val;
657 			ts->read_cnt++;
658 			return ADS7846_FILTER_REPEAT;
659 		} else {
660 			/*
661 			 * Maximum number of debouncing reached and still
662 			 * not enough number of consistent readings. Abort
663 			 * the whole sample, repeat it in the next sampling
664 			 * period.
665 			 */
666 			ts->read_cnt = 0;
667 			return ADS7846_FILTER_IGNORE;
668 		}
669 	} else {
670 		if (++ts->read_rep > ts->debounce_rep) {
671 			/*
672 			 * Got a good reading for this coordinate,
673 			 * go for the next one.
674 			 */
675 			ts->read_cnt = 0;
676 			ts->read_rep = 0;
677 			return ADS7846_FILTER_OK;
678 		} else {
679 			/* Read more values that are consistent. */
680 			ts->read_cnt++;
681 			return ADS7846_FILTER_REPEAT;
682 		}
683 	}
684 }
685 
686 static int ads7846_no_filter(void *ads, int data_idx, int *val)
687 {
688 	return ADS7846_FILTER_OK;
689 }
690 
691 static int ads7846_get_value(struct ads7846_buf *buf)
692 {
693 	int value;
694 
695 	value = be16_to_cpup(&buf->data);
696 
697 	/* enforce ADC output is 12 bits width */
698 	return (value >> 3) & 0xfff;
699 }
700 
701 static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx,
702 				u16 val)
703 {
704 	struct ads7846_packet *packet = ts->packet;
705 
706 	switch (cmd_idx) {
707 	case ADS7846_Y:
708 		packet->y = val;
709 		break;
710 	case ADS7846_X:
711 		packet->x = val;
712 		break;
713 	case ADS7846_Z1:
714 		packet->z1 = val;
715 		break;
716 	case ADS7846_Z2:
717 		packet->z2 = val;
718 		break;
719 	default:
720 		WARN_ON_ONCE(1);
721 	}
722 }
723 
724 static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref)
725 {
726 	switch (cmd_idx) {
727 	case ADS7846_Y:
728 		return READ_Y(vref);
729 	case ADS7846_X:
730 		return READ_X(vref);
731 
732 	/* 7846 specific commands  */
733 	case ADS7846_Z1:
734 		return READ_Z1(vref);
735 	case ADS7846_Z2:
736 		return READ_Z2(vref);
737 	case ADS7846_PWDOWN:
738 		return PWRDOWN;
739 	default:
740 		WARN_ON_ONCE(1);
741 	}
742 
743 	return 0;
744 }
745 
746 static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx)
747 {
748 	switch (cmd_idx) {
749 	case ADS7846_X:
750 	case ADS7846_Y:
751 	case ADS7846_Z1:
752 	case ADS7846_Z2:
753 		return true;
754 	case ADS7846_PWDOWN:
755 		return false;
756 	default:
757 		WARN_ON_ONCE(1);
758 	}
759 
760 	return false;
761 }
762 
763 static int ads7846_filter(struct ads7846 *ts)
764 {
765 	struct ads7846_packet *packet = ts->packet;
766 	int action;
767 	int val;
768 	unsigned int cmd_idx, b;
769 
770 	packet->ignore = false;
771 	for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) {
772 		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
773 
774 		packet->last_cmd_idx = cmd_idx;
775 
776 		for (b = l->skip; b < l->count; b++) {
777 			val = ads7846_get_value(&packet->rx[l->offset + b]);
778 
779 			action = ts->filter(ts->filter_data, cmd_idx, &val);
780 			if (action == ADS7846_FILTER_REPEAT) {
781 				if (b == l->count - 1)
782 					return -EAGAIN;
783 			} else if (action == ADS7846_FILTER_OK) {
784 				ads7846_set_cmd_val(ts, cmd_idx, val);
785 				break;
786 			} else {
787 				packet->ignore = true;
788 				return 0;
789 			}
790 		}
791 	}
792 
793 	return 0;
794 }
795 
796 static void ads7846_read_state(struct ads7846 *ts)
797 {
798 	struct ads7846_packet *packet = ts->packet;
799 	struct spi_message *m;
800 	int msg_idx = 0;
801 	int error;
802 
803 	packet->last_cmd_idx = 0;
804 
805 	while (true) {
806 		ts->wait_for_sync();
807 
808 		m = &ts->msg[msg_idx];
809 		error = spi_sync(ts->spi, m);
810 		if (error) {
811 			dev_err(&ts->spi->dev, "spi_sync --> %d\n", error);
812 			packet->ignore = true;
813 			return;
814 		}
815 
816 		error = ads7846_filter(ts);
817 		if (error)
818 			continue;
819 
820 		return;
821 	}
822 }
823 
824 static void ads7846_report_state(struct ads7846 *ts)
825 {
826 	struct ads7846_packet *packet = ts->packet;
827 	unsigned int Rt;
828 	u16 x, y, z1, z2;
829 
830 	x = packet->x;
831 	y = packet->y;
832 	if (ts->model == 7845) {
833 		z1 = 0;
834 		z2 = 0;
835 	} else {
836 		z1 = packet->z1;
837 		z2 = packet->z2;
838 	}
839 
840 	/* range filtering */
841 	if (x == MAX_12BIT)
842 		x = 0;
843 
844 	if (ts->model == 7843 || ts->model == 7845) {
845 		Rt = ts->pressure_max / 2;
846 	} else if (likely(x && z1)) {
847 		/* compute touch pressure resistance using equation #2 */
848 		Rt = z2;
849 		Rt -= z1;
850 		Rt *= ts->x_plate_ohms;
851 		Rt = DIV_ROUND_CLOSEST(Rt, 16);
852 		Rt *= x;
853 		Rt /= z1;
854 		Rt = DIV_ROUND_CLOSEST(Rt, 256);
855 	} else {
856 		Rt = 0;
857 	}
858 
859 	/*
860 	 * Sample found inconsistent by debouncing or pressure is beyond
861 	 * the maximum. Don't report it to user space, repeat at least
862 	 * once more the measurement
863 	 */
864 	if (packet->ignore || Rt > ts->pressure_max) {
865 		dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
866 			 packet->ignore, Rt);
867 		return;
868 	}
869 
870 	/*
871 	 * Maybe check the pendown state before reporting. This discards
872 	 * false readings when the pen is lifted.
873 	 */
874 	if (ts->penirq_recheck_delay_usecs) {
875 		udelay(ts->penirq_recheck_delay_usecs);
876 		if (!get_pendown_state(ts))
877 			Rt = 0;
878 	}
879 
880 	/*
881 	 * NOTE: We can't rely on the pressure to determine the pen down
882 	 * state, even this controller has a pressure sensor. The pressure
883 	 * value can fluctuate for quite a while after lifting the pen and
884 	 * in some cases may not even settle at the expected value.
885 	 *
886 	 * The only safe way to check for the pen up condition is in the
887 	 * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
888 	 */
889 	if (Rt) {
890 		struct input_dev *input = ts->input;
891 
892 		if (!ts->pendown) {
893 			input_report_key(input, BTN_TOUCH, 1);
894 			ts->pendown = true;
895 			dev_vdbg(&ts->spi->dev, "DOWN\n");
896 		}
897 
898 		touchscreen_report_pos(input, &ts->core_prop, x, y, false);
899 		input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
900 
901 		input_sync(input);
902 		dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
903 	}
904 }
905 
906 static irqreturn_t ads7846_hard_irq(int irq, void *handle)
907 {
908 	struct ads7846 *ts = handle;
909 
910 	return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
911 }
912 
913 
914 static irqreturn_t ads7846_irq(int irq, void *handle)
915 {
916 	struct ads7846 *ts = handle;
917 
918 	/* Start with a small delay before checking pendown state */
919 	msleep(TS_POLL_DELAY);
920 
921 	while (!ts->stopped && get_pendown_state(ts)) {
922 
923 		/* pen is down, continue with the measurement */
924 		ads7846_read_state(ts);
925 
926 		if (!ts->stopped)
927 			ads7846_report_state(ts);
928 
929 		wait_event_timeout(ts->wait, ts->stopped,
930 				   msecs_to_jiffies(TS_POLL_PERIOD));
931 	}
932 
933 	if (ts->pendown && !ts->stopped)
934 		ads7846_report_pen_up(ts);
935 
936 	return IRQ_HANDLED;
937 }
938 
939 static int ads7846_suspend(struct device *dev)
940 {
941 	struct ads7846 *ts = dev_get_drvdata(dev);
942 
943 	mutex_lock(&ts->lock);
944 
945 	if (!ts->suspended) {
946 
947 		if (!ts->disabled)
948 			__ads7846_disable(ts);
949 
950 		if (device_may_wakeup(&ts->spi->dev))
951 			enable_irq_wake(ts->spi->irq);
952 
953 		ts->suspended = true;
954 	}
955 
956 	mutex_unlock(&ts->lock);
957 
958 	return 0;
959 }
960 
961 static int ads7846_resume(struct device *dev)
962 {
963 	struct ads7846 *ts = dev_get_drvdata(dev);
964 
965 	mutex_lock(&ts->lock);
966 
967 	if (ts->suspended) {
968 
969 		ts->suspended = false;
970 
971 		if (device_may_wakeup(&ts->spi->dev))
972 			disable_irq_wake(ts->spi->irq);
973 
974 		if (!ts->disabled)
975 			__ads7846_enable(ts);
976 	}
977 
978 	mutex_unlock(&ts->lock);
979 
980 	return 0;
981 }
982 
983 static DEFINE_SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
984 
985 static int ads7846_setup_pendown(struct spi_device *spi,
986 				 struct ads7846 *ts,
987 				 const struct ads7846_platform_data *pdata)
988 {
989 	/*
990 	 * REVISIT when the irq can be triggered active-low, or if for some
991 	 * reason the touchscreen isn't hooked up, we don't need to access
992 	 * the pendown state.
993 	 */
994 
995 	if (pdata->get_pendown_state) {
996 		ts->get_pendown_state = pdata->get_pendown_state;
997 	} else {
998 		ts->gpio_pendown = gpiod_get(&spi->dev, "pendown", GPIOD_IN);
999 		if (IS_ERR(ts->gpio_pendown)) {
1000 			dev_err(&spi->dev, "failed to request pendown GPIO\n");
1001 			return PTR_ERR(ts->gpio_pendown);
1002 		}
1003 		if (pdata->gpio_pendown_debounce)
1004 			gpiod_set_debounce(ts->gpio_pendown,
1005 					   pdata->gpio_pendown_debounce);
1006 	}
1007 
1008 	return 0;
1009 }
1010 
1011 /*
1012  * Set up the transfers to read touchscreen state; this assumes we
1013  * use formula #2 for pressure, not #3.
1014  */
1015 static int ads7846_setup_spi_msg(struct ads7846 *ts,
1016 				  const struct ads7846_platform_data *pdata)
1017 {
1018 	struct spi_message *m = &ts->msg[0];
1019 	struct spi_transfer *x = ts->xfer;
1020 	struct ads7846_packet *packet = ts->packet;
1021 	int vref = pdata->keep_vref_on;
1022 	unsigned int count, offset = 0;
1023 	unsigned int cmd_idx, b;
1024 	unsigned long time;
1025 	size_t size = 0;
1026 
1027 	/* time per bit */
1028 	time = NSEC_PER_SEC / ts->spi->max_speed_hz;
1029 
1030 	count = pdata->settle_delay_usecs * NSEC_PER_USEC / time;
1031 	packet->count_skip = DIV_ROUND_UP(count, 24);
1032 
1033 	if (ts->debounce_max && ts->debounce_rep)
1034 		/* ads7846_debounce_filter() is making ts->debounce_rep + 2
1035 		 * reads. So we need to get all samples for normal case. */
1036 		packet->count = ts->debounce_rep + 2;
1037 	else
1038 		packet->count = 1;
1039 
1040 	if (ts->model == 7846)
1041 		packet->cmds = 5; /* x, y, z1, z2, pwdown */
1042 	else
1043 		packet->cmds = 3; /* x, y, pwdown */
1044 
1045 	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
1046 		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
1047 		unsigned int max_count;
1048 
1049 		if (cmd_idx == packet->cmds - 1)
1050 			cmd_idx = ADS7846_PWDOWN;
1051 
1052 		if (ads7846_cmd_need_settle(cmd_idx))
1053 			max_count = packet->count + packet->count_skip;
1054 		else
1055 			max_count = packet->count;
1056 
1057 		l->offset = offset;
1058 		offset += max_count;
1059 		l->count = max_count;
1060 		l->skip = packet->count_skip;
1061 		size += sizeof(*packet->tx) * max_count;
1062 	}
1063 
1064 	packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
1065 	if (!packet->tx)
1066 		return -ENOMEM;
1067 
1068 	packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
1069 	if (!packet->rx)
1070 		return -ENOMEM;
1071 
1072 	if (ts->model == 7873) {
1073 		/*
1074 		 * The AD7873 is almost identical to the ADS7846
1075 		 * keep VREF off during differential/ratiometric
1076 		 * conversion modes.
1077 		 */
1078 		ts->model = 7846;
1079 		vref = 0;
1080 	}
1081 
1082 	ts->msg_count = 1;
1083 	spi_message_init(m);
1084 	m->context = ts;
1085 
1086 	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
1087 		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
1088 		u8 cmd;
1089 
1090 		if (cmd_idx == packet->cmds - 1)
1091 			cmd_idx = ADS7846_PWDOWN;
1092 
1093 		cmd = ads7846_get_cmd(cmd_idx, vref);
1094 
1095 		for (b = 0; b < l->count; b++)
1096 			packet->tx[l->offset + b].cmd = cmd;
1097 	}
1098 
1099 	x->tx_buf = packet->tx;
1100 	x->rx_buf = packet->rx;
1101 	x->len = size;
1102 	spi_message_add_tail(x, m);
1103 
1104 	return 0;
1105 }
1106 
1107 static const struct of_device_id ads7846_dt_ids[] = {
1108 	{ .compatible = "ti,tsc2046",	.data = (void *) 7846 },
1109 	{ .compatible = "ti,ads7843",	.data = (void *) 7843 },
1110 	{ .compatible = "ti,ads7845",	.data = (void *) 7845 },
1111 	{ .compatible = "ti,ads7846",	.data = (void *) 7846 },
1112 	{ .compatible = "ti,ads7873",	.data = (void *) 7873 },
1113 	{ }
1114 };
1115 MODULE_DEVICE_TABLE(of, ads7846_dt_ids);
1116 
1117 static const struct ads7846_platform_data *ads7846_get_props(struct device *dev)
1118 {
1119 	struct ads7846_platform_data *pdata;
1120 	u32 value;
1121 
1122 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
1123 	if (!pdata)
1124 		return ERR_PTR(-ENOMEM);
1125 
1126 	pdata->model = (uintptr_t)device_get_match_data(dev);
1127 
1128 	device_property_read_u16(dev, "ti,vref-delay-usecs",
1129 				 &pdata->vref_delay_usecs);
1130 	device_property_read_u16(dev, "ti,vref-mv", &pdata->vref_mv);
1131 	pdata->keep_vref_on = device_property_read_bool(dev, "ti,keep-vref-on");
1132 
1133 	pdata->swap_xy = device_property_read_bool(dev, "ti,swap-xy");
1134 
1135 	device_property_read_u16(dev, "ti,settle-delay-usec",
1136 				 &pdata->settle_delay_usecs);
1137 	device_property_read_u16(dev, "ti,penirq-recheck-delay-usecs",
1138 				 &pdata->penirq_recheck_delay_usecs);
1139 
1140 	device_property_read_u16(dev, "ti,x-plate-ohms", &pdata->x_plate_ohms);
1141 	device_property_read_u16(dev, "ti,y-plate-ohms", &pdata->y_plate_ohms);
1142 
1143 	device_property_read_u16(dev, "ti,x-min", &pdata->x_min);
1144 	device_property_read_u16(dev, "ti,y-min", &pdata->y_min);
1145 	device_property_read_u16(dev, "ti,x-max", &pdata->x_max);
1146 	device_property_read_u16(dev, "ti,y-max", &pdata->y_max);
1147 
1148 	/*
1149 	 * touchscreen-max-pressure gets parsed during
1150 	 * touchscreen_parse_properties()
1151 	 */
1152 	device_property_read_u16(dev, "ti,pressure-min", &pdata->pressure_min);
1153 	if (!device_property_read_u32(dev, "touchscreen-min-pressure", &value))
1154 		pdata->pressure_min = (u16) value;
1155 	device_property_read_u16(dev, "ti,pressure-max", &pdata->pressure_max);
1156 
1157 	device_property_read_u16(dev, "ti,debounce-max", &pdata->debounce_max);
1158 	if (!device_property_read_u32(dev, "touchscreen-average-samples", &value))
1159 		pdata->debounce_max = (u16) value;
1160 	device_property_read_u16(dev, "ti,debounce-tol", &pdata->debounce_tol);
1161 	device_property_read_u16(dev, "ti,debounce-rep", &pdata->debounce_rep);
1162 
1163 	device_property_read_u32(dev, "ti,pendown-gpio-debounce",
1164 			     &pdata->gpio_pendown_debounce);
1165 
1166 	pdata->wakeup = device_property_read_bool(dev, "wakeup-source") ||
1167 			device_property_read_bool(dev, "linux,wakeup");
1168 
1169 	return pdata;
1170 }
1171 
1172 static void ads7846_regulator_disable(void *regulator)
1173 {
1174 	regulator_disable(regulator);
1175 }
1176 
1177 static int ads7846_probe(struct spi_device *spi)
1178 {
1179 	const struct ads7846_platform_data *pdata;
1180 	struct ads7846 *ts;
1181 	struct device *dev = &spi->dev;
1182 	struct ads7846_packet *packet;
1183 	struct input_dev *input_dev;
1184 	unsigned long irq_flags;
1185 	int err;
1186 
1187 	if (!spi->irq) {
1188 		dev_dbg(dev, "no IRQ?\n");
1189 		return -EINVAL;
1190 	}
1191 
1192 	/* don't exceed max specified sample rate */
1193 	if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
1194 		dev_err(dev, "f(sample) %d KHz?\n",
1195 			(spi->max_speed_hz/SAMPLE_BITS)/1000);
1196 		return -EINVAL;
1197 	}
1198 
1199 	/*
1200 	 * We'd set TX word size 8 bits and RX word size to 13 bits ... except
1201 	 * that even if the hardware can do that, the SPI controller driver
1202 	 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
1203 	 */
1204 	spi->bits_per_word = 8;
1205 	spi->mode &= ~SPI_MODE_X_MASK;
1206 	spi->mode |= SPI_MODE_0;
1207 	err = spi_setup(spi);
1208 	if (err < 0)
1209 		return err;
1210 
1211 	ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL);
1212 	if (!ts)
1213 		return -ENOMEM;
1214 
1215 	packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL);
1216 	if (!packet)
1217 		return -ENOMEM;
1218 
1219 	input_dev = devm_input_allocate_device(dev);
1220 	if (!input_dev)
1221 		return -ENOMEM;
1222 
1223 	spi_set_drvdata(spi, ts);
1224 
1225 	ts->packet = packet;
1226 	ts->spi = spi;
1227 	ts->input = input_dev;
1228 
1229 	mutex_init(&ts->lock);
1230 	init_waitqueue_head(&ts->wait);
1231 
1232 	pdata = dev_get_platdata(dev);
1233 	if (!pdata) {
1234 		pdata = ads7846_get_props(dev);
1235 		if (IS_ERR(pdata))
1236 			return PTR_ERR(pdata);
1237 	}
1238 
1239 	ts->model = pdata->model ? : 7846;
1240 	ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
1241 	ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
1242 	ts->vref_mv = pdata->vref_mv;
1243 
1244 	if (pdata->debounce_max) {
1245 		ts->debounce_max = pdata->debounce_max;
1246 		if (ts->debounce_max < 2)
1247 			ts->debounce_max = 2;
1248 		ts->debounce_tol = pdata->debounce_tol;
1249 		ts->debounce_rep = pdata->debounce_rep;
1250 		ts->filter = ads7846_debounce_filter;
1251 		ts->filter_data = ts;
1252 	} else {
1253 		ts->filter = ads7846_no_filter;
1254 	}
1255 
1256 	err = ads7846_setup_pendown(spi, ts, pdata);
1257 	if (err)
1258 		return err;
1259 
1260 	if (pdata->penirq_recheck_delay_usecs)
1261 		ts->penirq_recheck_delay_usecs =
1262 				pdata->penirq_recheck_delay_usecs;
1263 
1264 	ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
1265 
1266 	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
1267 	snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
1268 
1269 	input_dev->name = ts->name;
1270 	input_dev->phys = ts->phys;
1271 
1272 	input_dev->id.bustype = BUS_SPI;
1273 	input_dev->id.product = pdata->model;
1274 
1275 	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
1276 	input_set_abs_params(input_dev, ABS_X,
1277 			pdata->x_min ? : 0,
1278 			pdata->x_max ? : MAX_12BIT,
1279 			0, 0);
1280 	input_set_abs_params(input_dev, ABS_Y,
1281 			pdata->y_min ? : 0,
1282 			pdata->y_max ? : MAX_12BIT,
1283 			0, 0);
1284 	if (ts->model != 7845)
1285 		input_set_abs_params(input_dev, ABS_PRESSURE,
1286 				pdata->pressure_min, pdata->pressure_max, 0, 0);
1287 
1288 	/*
1289 	 * Parse common framework properties. Must be done here to ensure the
1290 	 * correct behaviour in case of using the legacy vendor bindings. The
1291 	 * general binding value overrides the vendor specific one.
1292 	 */
1293 	touchscreen_parse_properties(ts->input, false, &ts->core_prop);
1294 	ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0;
1295 
1296 	/*
1297 	 * Check if legacy ti,swap-xy binding is used instead of
1298 	 * touchscreen-swapped-x-y
1299 	 */
1300 	if (!ts->core_prop.swap_x_y && pdata->swap_xy) {
1301 		swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]);
1302 		ts->core_prop.swap_x_y = true;
1303 	}
1304 
1305 	ads7846_setup_spi_msg(ts, pdata);
1306 
1307 	ts->reg = devm_regulator_get(dev, "vcc");
1308 	if (IS_ERR(ts->reg)) {
1309 		err = PTR_ERR(ts->reg);
1310 		dev_err(dev, "unable to get regulator: %d\n", err);
1311 		return err;
1312 	}
1313 
1314 	err = regulator_enable(ts->reg);
1315 	if (err) {
1316 		dev_err(dev, "unable to enable regulator: %d\n", err);
1317 		return err;
1318 	}
1319 
1320 	err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg);
1321 	if (err)
1322 		return err;
1323 
1324 	irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
1325 	irq_flags |= IRQF_ONESHOT;
1326 
1327 	err = devm_request_threaded_irq(dev, spi->irq,
1328 					ads7846_hard_irq, ads7846_irq,
1329 					irq_flags, dev->driver->name, ts);
1330 	if (err && err != -EPROBE_DEFER && !pdata->irq_flags) {
1331 		dev_info(dev,
1332 			"trying pin change workaround on irq %d\n", spi->irq);
1333 		irq_flags |= IRQF_TRIGGER_RISING;
1334 		err = devm_request_threaded_irq(dev, spi->irq,
1335 						ads7846_hard_irq, ads7846_irq,
1336 						irq_flags, dev->driver->name,
1337 						ts);
1338 	}
1339 
1340 	if (err) {
1341 		dev_dbg(dev, "irq %d busy?\n", spi->irq);
1342 		return err;
1343 	}
1344 
1345 	err = ads784x_hwmon_register(spi, ts);
1346 	if (err)
1347 		return err;
1348 
1349 	dev_info(dev, "touchscreen, irq %d\n", spi->irq);
1350 
1351 	/*
1352 	 * Take a first sample, leaving nPENIRQ active and vREF off; avoid
1353 	 * the touchscreen, in case it's not connected.
1354 	 */
1355 	if (ts->model == 7845)
1356 		ads7845_read12_ser(dev, PWRDOWN);
1357 	else
1358 		(void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux));
1359 
1360 	err = devm_device_add_group(dev, &ads784x_attr_group);
1361 	if (err)
1362 		return err;
1363 
1364 	err = input_register_device(input_dev);
1365 	if (err)
1366 		return err;
1367 
1368 	device_init_wakeup(dev, pdata->wakeup);
1369 
1370 	/*
1371 	 * If device does not carry platform data we must have allocated it
1372 	 * when parsing DT data.
1373 	 */
1374 	if (!dev_get_platdata(dev))
1375 		devm_kfree(dev, (void *)pdata);
1376 
1377 	return 0;
1378 }
1379 
1380 static void ads7846_remove(struct spi_device *spi)
1381 {
1382 	struct ads7846 *ts = spi_get_drvdata(spi);
1383 
1384 	ads7846_stop(ts);
1385 }
1386 
1387 static struct spi_driver ads7846_driver = {
1388 	.driver = {
1389 		.name	= "ads7846",
1390 		.pm	= pm_sleep_ptr(&ads7846_pm),
1391 		.of_match_table = ads7846_dt_ids,
1392 	},
1393 	.probe		= ads7846_probe,
1394 	.remove		= ads7846_remove,
1395 };
1396 
1397 module_spi_driver(ads7846_driver);
1398 
1399 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1400 MODULE_LICENSE("GPL");
1401 MODULE_ALIAS("spi:ads7846");
1402