Loading...
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 <linux/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
63struct ads7846_buf {
64 u8 cmd;
65 __be16 data;
66} __packed;
67
68struct 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 */
79struct 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
94struct 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 struct gpio_desc *gpio_hsync;
142
143 void (*wait_for_sync)(void);
144};
145
146enum ads7846_filter {
147 ADS7846_FILTER_OK,
148 ADS7846_FILTER_REPEAT,
149 ADS7846_FILTER_IGNORE,
150};
151
152/* leave chip selected when we're done, for quicker re-select? */
153#if 0
154#define CS_CHANGE(xfer) ((xfer).cs_change = 1)
155#else
156#define CS_CHANGE(xfer) ((xfer).cs_change = 0)
157#endif
158
159/*--------------------------------------------------------------------------*/
160
161/* The ADS7846 has touchscreen and other sensors.
162 * Earlier ads784x chips are somewhat compatible.
163 */
164#define ADS_START (1 << 7)
165#define ADS_A2A1A0_d_y (1 << 4) /* differential */
166#define ADS_A2A1A0_d_z1 (3 << 4) /* differential */
167#define ADS_A2A1A0_d_z2 (4 << 4) /* differential */
168#define ADS_A2A1A0_d_x (5 << 4) /* differential */
169#define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */
170#define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */
171#define ADS_A2A1A0_vaux (6 << 4) /* non-differential */
172#define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */
173#define ADS_8_BIT (1 << 3)
174#define ADS_12_BIT (0 << 3)
175#define ADS_SER (1 << 2) /* non-differential */
176#define ADS_DFR (0 << 2) /* differential */
177#define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */
178#define ADS_PD10_ADC_ON (1 << 0) /* ADC on */
179#define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */
180#define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */
181
182#define MAX_12BIT ((1<<12)-1)
183
184/* leave ADC powered up (disables penirq) between differential samples */
185#define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
186 | ADS_12_BIT | ADS_DFR | \
187 (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
188
189#define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref))
190#define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref))
191#define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref))
192#define READ_X(vref) (READ_12BIT_DFR(x, 1, vref))
193#define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */
194
195/* single-ended samples need to first power up reference voltage;
196 * we leave both ADC and VREF powered
197 */
198#define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
199 | ADS_12_BIT | ADS_SER)
200
201#define REF_ON (READ_12BIT_DFR(x, 1, 1))
202#define REF_OFF (READ_12BIT_DFR(y, 0, 0))
203
204/* Order commands in the most optimal way to reduce Vref switching and
205 * settling time:
206 * Measure: X; Vref: X+, X-; IN: Y+
207 * Measure: Y; Vref: Y+, Y-; IN: X+
208 * Measure: Z1; Vref: Y+, X-; IN: X+
209 * Measure: Z2; Vref: Y+, X-; IN: Y-
210 */
211enum ads7846_cmds {
212 ADS7846_X,
213 ADS7846_Y,
214 ADS7846_Z1,
215 ADS7846_Z2,
216 ADS7846_PWDOWN,
217};
218
219static int get_pendown_state(struct ads7846 *ts)
220{
221 if (ts->get_pendown_state)
222 return ts->get_pendown_state();
223
224 return gpiod_get_value(ts->gpio_pendown);
225}
226
227static void ads7846_report_pen_up(struct ads7846 *ts)
228{
229 struct input_dev *input = ts->input;
230
231 input_report_key(input, BTN_TOUCH, 0);
232 input_report_abs(input, ABS_PRESSURE, 0);
233 input_sync(input);
234
235 ts->pendown = false;
236 dev_vdbg(&ts->spi->dev, "UP\n");
237}
238
239/* Must be called with ts->lock held */
240static void ads7846_stop(struct ads7846 *ts)
241{
242 if (!ts->disabled && !ts->suspended) {
243 /* Signal IRQ thread to stop polling and disable the handler. */
244 ts->stopped = true;
245 mb();
246 wake_up(&ts->wait);
247 disable_irq(ts->spi->irq);
248 }
249}
250
251/* Must be called with ts->lock held */
252static void ads7846_restart(struct ads7846 *ts)
253{
254 if (!ts->disabled && !ts->suspended) {
255 /* Check if pen was released since last stop */
256 if (ts->pendown && !get_pendown_state(ts))
257 ads7846_report_pen_up(ts);
258
259 /* Tell IRQ thread that it may poll the device. */
260 ts->stopped = false;
261 mb();
262 enable_irq(ts->spi->irq);
263 }
264}
265
266/* Must be called with ts->lock held */
267static void __ads7846_disable(struct ads7846 *ts)
268{
269 ads7846_stop(ts);
270 regulator_disable(ts->reg);
271
272 /*
273 * We know the chip's in low power mode since we always
274 * leave it that way after every request
275 */
276}
277
278/* Must be called with ts->lock held */
279static void __ads7846_enable(struct ads7846 *ts)
280{
281 int error;
282
283 error = regulator_enable(ts->reg);
284 if (error != 0)
285 dev_err(&ts->spi->dev, "Failed to enable supply: %d\n", error);
286
287 ads7846_restart(ts);
288}
289
290static void ads7846_disable(struct ads7846 *ts)
291{
292 mutex_lock(&ts->lock);
293
294 if (!ts->disabled) {
295
296 if (!ts->suspended)
297 __ads7846_disable(ts);
298
299 ts->disabled = true;
300 }
301
302 mutex_unlock(&ts->lock);
303}
304
305static void ads7846_enable(struct ads7846 *ts)
306{
307 mutex_lock(&ts->lock);
308
309 if (ts->disabled) {
310
311 ts->disabled = false;
312
313 if (!ts->suspended)
314 __ads7846_enable(ts);
315 }
316
317 mutex_unlock(&ts->lock);
318}
319
320/*--------------------------------------------------------------------------*/
321
322/*
323 * Non-touchscreen sensors only use single-ended conversions.
324 * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
325 * ads7846 lets that pin be unconnected, to use internal vREF.
326 */
327
328struct ser_req {
329 u8 ref_on;
330 u8 command;
331 u8 ref_off;
332 u16 scratch;
333 struct spi_message msg;
334 struct spi_transfer xfer[8];
335 /*
336 * DMA (thus cache coherency maintenance) requires the
337 * transfer buffers to live in their own cache lines.
338 */
339 __be16 sample ____cacheline_aligned;
340};
341
342struct ads7845_ser_req {
343 u8 command[3];
344 struct spi_message msg;
345 struct spi_transfer xfer[2];
346 /*
347 * DMA (thus cache coherency maintenance) requires the
348 * transfer buffers to live in their own cache lines.
349 */
350 u8 sample[3] ____cacheline_aligned;
351};
352
353static int ads7846_read12_ser(struct device *dev, unsigned command)
354{
355 struct spi_device *spi = to_spi_device(dev);
356 struct ads7846 *ts = dev_get_drvdata(dev);
357 struct ser_req *req;
358 int status;
359
360 req = kzalloc(sizeof *req, GFP_KERNEL);
361 if (!req)
362 return -ENOMEM;
363
364 spi_message_init(&req->msg);
365
366 /* maybe turn on internal vREF, and let it settle */
367 if (ts->use_internal) {
368 req->ref_on = REF_ON;
369 req->xfer[0].tx_buf = &req->ref_on;
370 req->xfer[0].len = 1;
371 spi_message_add_tail(&req->xfer[0], &req->msg);
372
373 req->xfer[1].rx_buf = &req->scratch;
374 req->xfer[1].len = 2;
375
376 /* for 1uF, settle for 800 usec; no cap, 100 usec. */
377 req->xfer[1].delay.value = ts->vref_delay_usecs;
378 req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS;
379 spi_message_add_tail(&req->xfer[1], &req->msg);
380
381 /* Enable reference voltage */
382 command |= ADS_PD10_REF_ON;
383 }
384
385 /* Enable ADC in every case */
386 command |= ADS_PD10_ADC_ON;
387
388 /* take sample */
389 req->command = (u8) command;
390 req->xfer[2].tx_buf = &req->command;
391 req->xfer[2].len = 1;
392 spi_message_add_tail(&req->xfer[2], &req->msg);
393
394 req->xfer[3].rx_buf = &req->sample;
395 req->xfer[3].len = 2;
396 spi_message_add_tail(&req->xfer[3], &req->msg);
397
398 /* REVISIT: take a few more samples, and compare ... */
399
400 /* converter in low power mode & enable PENIRQ */
401 req->ref_off = PWRDOWN;
402 req->xfer[4].tx_buf = &req->ref_off;
403 req->xfer[4].len = 1;
404 spi_message_add_tail(&req->xfer[4], &req->msg);
405
406 req->xfer[5].rx_buf = &req->scratch;
407 req->xfer[5].len = 2;
408 spi_message_add_tail(&req->xfer[5], &req->msg);
409
410 /* clear the command register */
411 req->scratch = 0;
412 req->xfer[6].tx_buf = &req->scratch;
413 req->xfer[6].len = 1;
414 spi_message_add_tail(&req->xfer[6], &req->msg);
415
416 req->xfer[7].rx_buf = &req->scratch;
417 req->xfer[7].len = 2;
418 CS_CHANGE(req->xfer[7]);
419 spi_message_add_tail(&req->xfer[7], &req->msg);
420
421 mutex_lock(&ts->lock);
422 ads7846_stop(ts);
423 status = spi_sync(spi, &req->msg);
424 ads7846_restart(ts);
425 mutex_unlock(&ts->lock);
426
427 if (status == 0) {
428 /* on-wire is a must-ignore bit, a BE12 value, then padding */
429 status = be16_to_cpu(req->sample);
430 status = status >> 3;
431 status &= 0x0fff;
432 }
433
434 kfree(req);
435 return status;
436}
437
438static int ads7845_read12_ser(struct device *dev, unsigned command)
439{
440 struct spi_device *spi = to_spi_device(dev);
441 struct ads7846 *ts = dev_get_drvdata(dev);
442 struct ads7845_ser_req *req;
443 int status;
444
445 req = kzalloc(sizeof *req, GFP_KERNEL);
446 if (!req)
447 return -ENOMEM;
448
449 spi_message_init(&req->msg);
450
451 req->command[0] = (u8) command;
452 req->xfer[0].tx_buf = req->command;
453 req->xfer[0].rx_buf = req->sample;
454 req->xfer[0].len = 3;
455 spi_message_add_tail(&req->xfer[0], &req->msg);
456
457 mutex_lock(&ts->lock);
458 ads7846_stop(ts);
459 status = spi_sync(spi, &req->msg);
460 ads7846_restart(ts);
461 mutex_unlock(&ts->lock);
462
463 if (status == 0) {
464 /* BE12 value, then padding */
465 status = get_unaligned_be16(&req->sample[1]);
466 status = status >> 3;
467 status &= 0x0fff;
468 }
469
470 kfree(req);
471 return status;
472}
473
474#if IS_ENABLED(CONFIG_HWMON)
475
476#define SHOW(name, var, adjust) static ssize_t \
477name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
478{ \
479 struct ads7846 *ts = dev_get_drvdata(dev); \
480 ssize_t v = ads7846_read12_ser(&ts->spi->dev, \
481 READ_12BIT_SER(var)); \
482 if (v < 0) \
483 return v; \
484 return sprintf(buf, "%u\n", adjust(ts, v)); \
485} \
486static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
487
488
489/* Sysfs conventions report temperatures in millidegrees Celsius.
490 * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
491 * accuracy scheme without calibration data. For now we won't try either;
492 * userspace sees raw sensor values, and must scale/calibrate appropriately.
493 */
494static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
495{
496 return v;
497}
498
499SHOW(temp0, temp0, null_adjust) /* temp1_input */
500SHOW(temp1, temp1, null_adjust) /* temp2_input */
501
502
503/* sysfs conventions report voltages in millivolts. We can convert voltages
504 * if we know vREF. userspace may need to scale vAUX to match the board's
505 * external resistors; we assume that vBATT only uses the internal ones.
506 */
507static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
508{
509 unsigned retval = v;
510
511 /* external resistors may scale vAUX into 0..vREF */
512 retval *= ts->vref_mv;
513 retval = retval >> 12;
514
515 return retval;
516}
517
518static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
519{
520 unsigned retval = vaux_adjust(ts, v);
521
522 /* ads7846 has a resistor ladder to scale this signal down */
523 if (ts->model == 7846)
524 retval *= 4;
525
526 return retval;
527}
528
529SHOW(in0_input, vaux, vaux_adjust)
530SHOW(in1_input, vbatt, vbatt_adjust)
531
532static umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr,
533 int index)
534{
535 struct device *dev = kobj_to_dev(kobj);
536 struct ads7846 *ts = dev_get_drvdata(dev);
537
538 if (ts->model == 7843 && index < 2) /* in0, in1 */
539 return 0;
540 if (ts->model == 7845 && index != 2) /* in0 */
541 return 0;
542
543 return attr->mode;
544}
545
546static struct attribute *ads7846_attributes[] = {
547 &dev_attr_temp0.attr, /* 0 */
548 &dev_attr_temp1.attr, /* 1 */
549 &dev_attr_in0_input.attr, /* 2 */
550 &dev_attr_in1_input.attr, /* 3 */
551 NULL,
552};
553
554static const struct attribute_group ads7846_attr_group = {
555 .attrs = ads7846_attributes,
556 .is_visible = ads7846_is_visible,
557};
558__ATTRIBUTE_GROUPS(ads7846_attr);
559
560static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
561{
562 struct device *hwmon;
563
564 /* hwmon sensors need a reference voltage */
565 switch (ts->model) {
566 case 7846:
567 if (!ts->vref_mv) {
568 dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
569 ts->vref_mv = 2500;
570 ts->use_internal = true;
571 }
572 break;
573 case 7845:
574 case 7843:
575 if (!ts->vref_mv) {
576 dev_warn(&spi->dev,
577 "external vREF for ADS%d not specified\n",
578 ts->model);
579 return 0;
580 }
581 break;
582 }
583
584 hwmon = devm_hwmon_device_register_with_groups(&spi->dev,
585 spi->modalias, ts,
586 ads7846_attr_groups);
587
588 return PTR_ERR_OR_ZERO(hwmon);
589}
590
591#else
592static inline int ads784x_hwmon_register(struct spi_device *spi,
593 struct ads7846 *ts)
594{
595 return 0;
596}
597#endif
598
599static ssize_t ads7846_pen_down_show(struct device *dev,
600 struct device_attribute *attr, char *buf)
601{
602 struct ads7846 *ts = dev_get_drvdata(dev);
603
604 return sprintf(buf, "%u\n", ts->pendown);
605}
606
607static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
608
609static ssize_t ads7846_disable_show(struct device *dev,
610 struct device_attribute *attr, char *buf)
611{
612 struct ads7846 *ts = dev_get_drvdata(dev);
613
614 return sprintf(buf, "%u\n", ts->disabled);
615}
616
617static ssize_t ads7846_disable_store(struct device *dev,
618 struct device_attribute *attr,
619 const char *buf, size_t count)
620{
621 struct ads7846 *ts = dev_get_drvdata(dev);
622 unsigned int i;
623 int err;
624
625 err = kstrtouint(buf, 10, &i);
626 if (err)
627 return err;
628
629 if (i)
630 ads7846_disable(ts);
631 else
632 ads7846_enable(ts);
633
634 return count;
635}
636
637static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
638
639static struct attribute *ads784x_attrs[] = {
640 &dev_attr_pen_down.attr,
641 &dev_attr_disable.attr,
642 NULL,
643};
644ATTRIBUTE_GROUPS(ads784x);
645
646/*--------------------------------------------------------------------------*/
647
648static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
649{
650 struct ads7846 *ts = ads;
651
652 if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
653 /* Start over collecting consistent readings. */
654 ts->read_rep = 0;
655 /*
656 * Repeat it, if this was the first read or the read
657 * wasn't consistent enough.
658 */
659 if (ts->read_cnt < ts->debounce_max) {
660 ts->last_read = *val;
661 ts->read_cnt++;
662 return ADS7846_FILTER_REPEAT;
663 } else {
664 /*
665 * Maximum number of debouncing reached and still
666 * not enough number of consistent readings. Abort
667 * the whole sample, repeat it in the next sampling
668 * period.
669 */
670 ts->read_cnt = 0;
671 return ADS7846_FILTER_IGNORE;
672 }
673 } else {
674 if (++ts->read_rep > ts->debounce_rep) {
675 /*
676 * Got a good reading for this coordinate,
677 * go for the next one.
678 */
679 ts->read_cnt = 0;
680 ts->read_rep = 0;
681 return ADS7846_FILTER_OK;
682 } else {
683 /* Read more values that are consistent. */
684 ts->read_cnt++;
685 return ADS7846_FILTER_REPEAT;
686 }
687 }
688}
689
690static int ads7846_no_filter(void *ads, int data_idx, int *val)
691{
692 return ADS7846_FILTER_OK;
693}
694
695static int ads7846_get_value(struct ads7846_buf *buf)
696{
697 int value;
698
699 value = be16_to_cpup(&buf->data);
700
701 /* enforce ADC output is 12 bits width */
702 return (value >> 3) & 0xfff;
703}
704
705static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx,
706 u16 val)
707{
708 struct ads7846_packet *packet = ts->packet;
709
710 switch (cmd_idx) {
711 case ADS7846_Y:
712 packet->y = val;
713 break;
714 case ADS7846_X:
715 packet->x = val;
716 break;
717 case ADS7846_Z1:
718 packet->z1 = val;
719 break;
720 case ADS7846_Z2:
721 packet->z2 = val;
722 break;
723 default:
724 WARN_ON_ONCE(1);
725 }
726}
727
728static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref)
729{
730 switch (cmd_idx) {
731 case ADS7846_Y:
732 return READ_Y(vref);
733 case ADS7846_X:
734 return READ_X(vref);
735
736 /* 7846 specific commands */
737 case ADS7846_Z1:
738 return READ_Z1(vref);
739 case ADS7846_Z2:
740 return READ_Z2(vref);
741 case ADS7846_PWDOWN:
742 return PWRDOWN;
743 default:
744 WARN_ON_ONCE(1);
745 }
746
747 return 0;
748}
749
750static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx)
751{
752 switch (cmd_idx) {
753 case ADS7846_X:
754 case ADS7846_Y:
755 case ADS7846_Z1:
756 case ADS7846_Z2:
757 return true;
758 case ADS7846_PWDOWN:
759 return false;
760 default:
761 WARN_ON_ONCE(1);
762 }
763
764 return false;
765}
766
767static int ads7846_filter(struct ads7846 *ts)
768{
769 struct ads7846_packet *packet = ts->packet;
770 int action;
771 int val;
772 unsigned int cmd_idx, b;
773
774 packet->ignore = false;
775 for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) {
776 struct ads7846_buf_layout *l = &packet->l[cmd_idx];
777
778 packet->last_cmd_idx = cmd_idx;
779
780 for (b = l->skip; b < l->count; b++) {
781 val = ads7846_get_value(&packet->rx[l->offset + b]);
782
783 action = ts->filter(ts->filter_data, cmd_idx, &val);
784 if (action == ADS7846_FILTER_REPEAT) {
785 if (b == l->count - 1)
786 return -EAGAIN;
787 } else if (action == ADS7846_FILTER_OK) {
788 ads7846_set_cmd_val(ts, cmd_idx, val);
789 break;
790 } else {
791 packet->ignore = true;
792 return 0;
793 }
794 }
795 }
796
797 return 0;
798}
799
800static void ads7846_wait_for_hsync(struct ads7846 *ts)
801{
802 if (ts->wait_for_sync) {
803 ts->wait_for_sync();
804 return;
805 }
806
807 if (!ts->gpio_hsync)
808 return;
809
810 /*
811 * Wait for HSYNC to assert the line should be flagged
812 * as active low so here we are waiting for it to assert
813 */
814 while (!gpiod_get_value(ts->gpio_hsync))
815 cpu_relax();
816
817 /* Then we wait for it do de-assert */
818 while (gpiod_get_value(ts->gpio_hsync))
819 cpu_relax();
820}
821
822static void ads7846_read_state(struct ads7846 *ts)
823{
824 struct ads7846_packet *packet = ts->packet;
825 struct spi_message *m;
826 int msg_idx = 0;
827 int error;
828
829 packet->last_cmd_idx = 0;
830
831 while (true) {
832 ads7846_wait_for_hsync(ts);
833
834 m = &ts->msg[msg_idx];
835 error = spi_sync(ts->spi, m);
836 if (error) {
837 dev_err_ratelimited(&ts->spi->dev, "spi_sync --> %d\n", error);
838 packet->ignore = true;
839 return;
840 }
841
842 error = ads7846_filter(ts);
843 if (error)
844 continue;
845
846 return;
847 }
848}
849
850static void ads7846_report_state(struct ads7846 *ts)
851{
852 struct ads7846_packet *packet = ts->packet;
853 unsigned int Rt;
854 u16 x, y, z1, z2;
855
856 x = packet->x;
857 y = packet->y;
858 if (ts->model == 7845) {
859 z1 = 0;
860 z2 = 0;
861 } else {
862 z1 = packet->z1;
863 z2 = packet->z2;
864 }
865
866 /* range filtering */
867 if (x == MAX_12BIT)
868 x = 0;
869
870 if (ts->model == 7843 || ts->model == 7845) {
871 Rt = ts->pressure_max / 2;
872 } else if (likely(x && z1)) {
873 /* compute touch pressure resistance using equation #2 */
874 Rt = z2;
875 Rt -= z1;
876 Rt *= ts->x_plate_ohms;
877 Rt = DIV_ROUND_CLOSEST(Rt, 16);
878 Rt *= x;
879 Rt /= z1;
880 Rt = DIV_ROUND_CLOSEST(Rt, 256);
881 } else {
882 Rt = 0;
883 }
884
885 /*
886 * Sample found inconsistent by debouncing or pressure is beyond
887 * the maximum. Don't report it to user space, repeat at least
888 * once more the measurement
889 */
890 if (packet->ignore || Rt > ts->pressure_max) {
891 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
892 packet->ignore, Rt);
893 return;
894 }
895
896 /*
897 * Maybe check the pendown state before reporting. This discards
898 * false readings when the pen is lifted.
899 */
900 if (ts->penirq_recheck_delay_usecs) {
901 udelay(ts->penirq_recheck_delay_usecs);
902 if (!get_pendown_state(ts))
903 Rt = 0;
904 }
905
906 /*
907 * NOTE: We can't rely on the pressure to determine the pen down
908 * state, even this controller has a pressure sensor. The pressure
909 * value can fluctuate for quite a while after lifting the pen and
910 * in some cases may not even settle at the expected value.
911 *
912 * The only safe way to check for the pen up condition is in the
913 * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
914 */
915 if (Rt) {
916 struct input_dev *input = ts->input;
917
918 if (!ts->pendown) {
919 input_report_key(input, BTN_TOUCH, 1);
920 ts->pendown = true;
921 dev_vdbg(&ts->spi->dev, "DOWN\n");
922 }
923
924 touchscreen_report_pos(input, &ts->core_prop, x, y, false);
925 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
926
927 input_sync(input);
928 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
929 }
930}
931
932static irqreturn_t ads7846_hard_irq(int irq, void *handle)
933{
934 struct ads7846 *ts = handle;
935
936 return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
937}
938
939
940static irqreturn_t ads7846_irq(int irq, void *handle)
941{
942 struct ads7846 *ts = handle;
943
944 /* Start with a small delay before checking pendown state */
945 msleep(TS_POLL_DELAY);
946
947 while (!ts->stopped && get_pendown_state(ts)) {
948
949 /* pen is down, continue with the measurement */
950 ads7846_read_state(ts);
951
952 if (!ts->stopped)
953 ads7846_report_state(ts);
954
955 wait_event_timeout(ts->wait, ts->stopped,
956 msecs_to_jiffies(TS_POLL_PERIOD));
957 }
958
959 if (ts->pendown && !ts->stopped)
960 ads7846_report_pen_up(ts);
961
962 return IRQ_HANDLED;
963}
964
965static int ads7846_suspend(struct device *dev)
966{
967 struct ads7846 *ts = dev_get_drvdata(dev);
968
969 mutex_lock(&ts->lock);
970
971 if (!ts->suspended) {
972
973 if (!ts->disabled)
974 __ads7846_disable(ts);
975
976 if (device_may_wakeup(&ts->spi->dev))
977 enable_irq_wake(ts->spi->irq);
978
979 ts->suspended = true;
980 }
981
982 mutex_unlock(&ts->lock);
983
984 return 0;
985}
986
987static int ads7846_resume(struct device *dev)
988{
989 struct ads7846 *ts = dev_get_drvdata(dev);
990
991 mutex_lock(&ts->lock);
992
993 if (ts->suspended) {
994
995 ts->suspended = false;
996
997 if (device_may_wakeup(&ts->spi->dev))
998 disable_irq_wake(ts->spi->irq);
999
1000 if (!ts->disabled)
1001 __ads7846_enable(ts);
1002 }
1003
1004 mutex_unlock(&ts->lock);
1005
1006 return 0;
1007}
1008
1009static DEFINE_SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
1010
1011static int ads7846_setup_pendown(struct spi_device *spi,
1012 struct ads7846 *ts,
1013 const struct ads7846_platform_data *pdata)
1014{
1015 /*
1016 * REVISIT when the irq can be triggered active-low, or if for some
1017 * reason the touchscreen isn't hooked up, we don't need to access
1018 * the pendown state.
1019 */
1020
1021 if (pdata->get_pendown_state) {
1022 ts->get_pendown_state = pdata->get_pendown_state;
1023 } else {
1024 ts->gpio_pendown = gpiod_get(&spi->dev, "pendown", GPIOD_IN);
1025 if (IS_ERR(ts->gpio_pendown)) {
1026 dev_err(&spi->dev, "failed to request pendown GPIO\n");
1027 return PTR_ERR(ts->gpio_pendown);
1028 }
1029 if (pdata->gpio_pendown_debounce)
1030 gpiod_set_debounce(ts->gpio_pendown,
1031 pdata->gpio_pendown_debounce);
1032 }
1033
1034 return 0;
1035}
1036
1037/*
1038 * Set up the transfers to read touchscreen state; this assumes we
1039 * use formula #2 for pressure, not #3.
1040 */
1041static int ads7846_setup_spi_msg(struct ads7846 *ts,
1042 const struct ads7846_platform_data *pdata)
1043{
1044 struct spi_message *m = &ts->msg[0];
1045 struct spi_transfer *x = ts->xfer;
1046 struct ads7846_packet *packet = ts->packet;
1047 int vref = pdata->keep_vref_on;
1048 unsigned int count, offset = 0;
1049 unsigned int cmd_idx, b;
1050 unsigned long time;
1051 size_t size = 0;
1052
1053 /* time per bit */
1054 time = NSEC_PER_SEC / ts->spi->max_speed_hz;
1055
1056 count = pdata->settle_delay_usecs * NSEC_PER_USEC / time;
1057 packet->count_skip = DIV_ROUND_UP(count, 24);
1058
1059 if (ts->debounce_max && ts->debounce_rep)
1060 /* ads7846_debounce_filter() is making ts->debounce_rep + 2
1061 * reads. So we need to get all samples for normal case. */
1062 packet->count = ts->debounce_rep + 2;
1063 else
1064 packet->count = 1;
1065
1066 if (ts->model == 7846)
1067 packet->cmds = 5; /* x, y, z1, z2, pwdown */
1068 else
1069 packet->cmds = 3; /* x, y, pwdown */
1070
1071 for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
1072 struct ads7846_buf_layout *l = &packet->l[cmd_idx];
1073 unsigned int max_count;
1074
1075 if (cmd_idx == packet->cmds - 1)
1076 cmd_idx = ADS7846_PWDOWN;
1077
1078 if (ads7846_cmd_need_settle(cmd_idx))
1079 max_count = packet->count + packet->count_skip;
1080 else
1081 max_count = packet->count;
1082
1083 l->offset = offset;
1084 offset += max_count;
1085 l->count = max_count;
1086 l->skip = packet->count_skip;
1087 size += sizeof(*packet->tx) * max_count;
1088 }
1089
1090 packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
1091 if (!packet->tx)
1092 return -ENOMEM;
1093
1094 packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
1095 if (!packet->rx)
1096 return -ENOMEM;
1097
1098 if (ts->model == 7873) {
1099 /*
1100 * The AD7873 is almost identical to the ADS7846
1101 * keep VREF off during differential/ratiometric
1102 * conversion modes.
1103 */
1104 ts->model = 7846;
1105 vref = 0;
1106 }
1107
1108 ts->msg_count = 1;
1109 spi_message_init(m);
1110 m->context = ts;
1111
1112 for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
1113 struct ads7846_buf_layout *l = &packet->l[cmd_idx];
1114 u8 cmd;
1115
1116 if (cmd_idx == packet->cmds - 1)
1117 cmd_idx = ADS7846_PWDOWN;
1118
1119 cmd = ads7846_get_cmd(cmd_idx, vref);
1120
1121 for (b = 0; b < l->count; b++)
1122 packet->tx[l->offset + b].cmd = cmd;
1123 }
1124
1125 x->tx_buf = packet->tx;
1126 x->rx_buf = packet->rx;
1127 x->len = size;
1128 spi_message_add_tail(x, m);
1129
1130 return 0;
1131}
1132
1133static const struct of_device_id ads7846_dt_ids[] = {
1134 { .compatible = "ti,tsc2046", .data = (void *) 7846 },
1135 { .compatible = "ti,ads7843", .data = (void *) 7843 },
1136 { .compatible = "ti,ads7845", .data = (void *) 7845 },
1137 { .compatible = "ti,ads7846", .data = (void *) 7846 },
1138 { .compatible = "ti,ads7873", .data = (void *) 7873 },
1139 { }
1140};
1141MODULE_DEVICE_TABLE(of, ads7846_dt_ids);
1142
1143static const struct spi_device_id ads7846_spi_ids[] = {
1144 { "tsc2046", 7846 },
1145 { "ads7843", 7843 },
1146 { "ads7845", 7845 },
1147 { "ads7846", 7846 },
1148 { "ads7873", 7873 },
1149 { },
1150};
1151MODULE_DEVICE_TABLE(spi, ads7846_spi_ids);
1152
1153static const struct ads7846_platform_data *ads7846_get_props(struct device *dev)
1154{
1155 struct ads7846_platform_data *pdata;
1156 u32 value;
1157
1158 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
1159 if (!pdata)
1160 return ERR_PTR(-ENOMEM);
1161
1162 pdata->model = (uintptr_t)device_get_match_data(dev);
1163
1164 device_property_read_u16(dev, "ti,vref-delay-usecs",
1165 &pdata->vref_delay_usecs);
1166 device_property_read_u16(dev, "ti,vref-mv", &pdata->vref_mv);
1167 pdata->keep_vref_on = device_property_read_bool(dev, "ti,keep-vref-on");
1168
1169 pdata->swap_xy = device_property_read_bool(dev, "ti,swap-xy");
1170
1171 device_property_read_u16(dev, "ti,settle-delay-usec",
1172 &pdata->settle_delay_usecs);
1173 device_property_read_u16(dev, "ti,penirq-recheck-delay-usecs",
1174 &pdata->penirq_recheck_delay_usecs);
1175
1176 device_property_read_u16(dev, "ti,x-plate-ohms", &pdata->x_plate_ohms);
1177 device_property_read_u16(dev, "ti,y-plate-ohms", &pdata->y_plate_ohms);
1178
1179 device_property_read_u16(dev, "ti,x-min", &pdata->x_min);
1180 device_property_read_u16(dev, "ti,y-min", &pdata->y_min);
1181 device_property_read_u16(dev, "ti,x-max", &pdata->x_max);
1182 device_property_read_u16(dev, "ti,y-max", &pdata->y_max);
1183
1184 /*
1185 * touchscreen-max-pressure gets parsed during
1186 * touchscreen_parse_properties()
1187 */
1188 device_property_read_u16(dev, "ti,pressure-min", &pdata->pressure_min);
1189 if (!device_property_read_u32(dev, "touchscreen-min-pressure", &value))
1190 pdata->pressure_min = (u16) value;
1191 device_property_read_u16(dev, "ti,pressure-max", &pdata->pressure_max);
1192
1193 device_property_read_u16(dev, "ti,debounce-max", &pdata->debounce_max);
1194 if (!device_property_read_u32(dev, "touchscreen-average-samples", &value))
1195 pdata->debounce_max = (u16) value;
1196 device_property_read_u16(dev, "ti,debounce-tol", &pdata->debounce_tol);
1197 device_property_read_u16(dev, "ti,debounce-rep", &pdata->debounce_rep);
1198
1199 device_property_read_u32(dev, "ti,pendown-gpio-debounce",
1200 &pdata->gpio_pendown_debounce);
1201
1202 pdata->wakeup = device_property_read_bool(dev, "wakeup-source") ||
1203 device_property_read_bool(dev, "linux,wakeup");
1204
1205 return pdata;
1206}
1207
1208static void ads7846_regulator_disable(void *regulator)
1209{
1210 regulator_disable(regulator);
1211}
1212
1213static int ads7846_probe(struct spi_device *spi)
1214{
1215 const struct ads7846_platform_data *pdata;
1216 struct ads7846 *ts;
1217 struct device *dev = &spi->dev;
1218 struct ads7846_packet *packet;
1219 struct input_dev *input_dev;
1220 unsigned long irq_flags;
1221 int err;
1222
1223 if (!spi->irq) {
1224 dev_dbg(dev, "no IRQ?\n");
1225 return -EINVAL;
1226 }
1227
1228 /* don't exceed max specified sample rate */
1229 if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
1230 dev_err(dev, "f(sample) %d KHz?\n",
1231 (spi->max_speed_hz/SAMPLE_BITS)/1000);
1232 return -EINVAL;
1233 }
1234
1235 /*
1236 * We'd set TX word size 8 bits and RX word size to 13 bits ... except
1237 * that even if the hardware can do that, the SPI controller driver
1238 * may not. So we stick to very-portable 8 bit words, both RX and TX.
1239 */
1240 spi->bits_per_word = 8;
1241 spi->mode &= ~SPI_MODE_X_MASK;
1242 spi->mode |= SPI_MODE_0;
1243 err = spi_setup(spi);
1244 if (err < 0)
1245 return err;
1246
1247 ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL);
1248 if (!ts)
1249 return -ENOMEM;
1250
1251 packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL);
1252 if (!packet)
1253 return -ENOMEM;
1254
1255 input_dev = devm_input_allocate_device(dev);
1256 if (!input_dev)
1257 return -ENOMEM;
1258
1259 spi_set_drvdata(spi, ts);
1260
1261 ts->packet = packet;
1262 ts->spi = spi;
1263 ts->input = input_dev;
1264
1265 mutex_init(&ts->lock);
1266 init_waitqueue_head(&ts->wait);
1267
1268 pdata = dev_get_platdata(dev);
1269 if (!pdata) {
1270 pdata = ads7846_get_props(dev);
1271 if (IS_ERR(pdata))
1272 return PTR_ERR(pdata);
1273 }
1274
1275 ts->model = pdata->model ? : 7846;
1276 ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
1277 ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
1278 ts->vref_mv = pdata->vref_mv;
1279
1280 if (pdata->debounce_max) {
1281 ts->debounce_max = pdata->debounce_max;
1282 if (ts->debounce_max < 2)
1283 ts->debounce_max = 2;
1284 ts->debounce_tol = pdata->debounce_tol;
1285 ts->debounce_rep = pdata->debounce_rep;
1286 ts->filter = ads7846_debounce_filter;
1287 ts->filter_data = ts;
1288 } else {
1289 ts->filter = ads7846_no_filter;
1290 }
1291
1292 err = ads7846_setup_pendown(spi, ts, pdata);
1293 if (err)
1294 return err;
1295
1296 if (pdata->penirq_recheck_delay_usecs)
1297 ts->penirq_recheck_delay_usecs =
1298 pdata->penirq_recheck_delay_usecs;
1299
1300 ts->wait_for_sync = pdata->wait_for_sync;
1301
1302 ts->gpio_hsync = devm_gpiod_get_optional(dev, "ti,hsync", GPIOD_IN);
1303 if (IS_ERR(ts->gpio_hsync))
1304 return PTR_ERR(ts->gpio_hsync);
1305
1306 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
1307 snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
1308
1309 input_dev->name = ts->name;
1310 input_dev->phys = ts->phys;
1311
1312 input_dev->id.bustype = BUS_SPI;
1313 input_dev->id.product = pdata->model;
1314
1315 input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
1316 input_set_abs_params(input_dev, ABS_X,
1317 pdata->x_min ? : 0,
1318 pdata->x_max ? : MAX_12BIT,
1319 0, 0);
1320 input_set_abs_params(input_dev, ABS_Y,
1321 pdata->y_min ? : 0,
1322 pdata->y_max ? : MAX_12BIT,
1323 0, 0);
1324 if (ts->model != 7845)
1325 input_set_abs_params(input_dev, ABS_PRESSURE,
1326 pdata->pressure_min, pdata->pressure_max, 0, 0);
1327
1328 /*
1329 * Parse common framework properties. Must be done here to ensure the
1330 * correct behaviour in case of using the legacy vendor bindings. The
1331 * general binding value overrides the vendor specific one.
1332 */
1333 touchscreen_parse_properties(ts->input, false, &ts->core_prop);
1334 ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0;
1335
1336 /*
1337 * Check if legacy ti,swap-xy binding is used instead of
1338 * touchscreen-swapped-x-y
1339 */
1340 if (!ts->core_prop.swap_x_y && pdata->swap_xy) {
1341 swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]);
1342 ts->core_prop.swap_x_y = true;
1343 }
1344
1345 ads7846_setup_spi_msg(ts, pdata);
1346
1347 ts->reg = devm_regulator_get(dev, "vcc");
1348 if (IS_ERR(ts->reg)) {
1349 err = PTR_ERR(ts->reg);
1350 dev_err(dev, "unable to get regulator: %d\n", err);
1351 return err;
1352 }
1353
1354 err = regulator_enable(ts->reg);
1355 if (err) {
1356 dev_err(dev, "unable to enable regulator: %d\n", err);
1357 return err;
1358 }
1359
1360 err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg);
1361 if (err)
1362 return err;
1363
1364 irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
1365 irq_flags |= IRQF_ONESHOT;
1366
1367 err = devm_request_threaded_irq(dev, spi->irq,
1368 ads7846_hard_irq, ads7846_irq,
1369 irq_flags, dev->driver->name, ts);
1370 if (err && err != -EPROBE_DEFER && !pdata->irq_flags) {
1371 dev_info(dev,
1372 "trying pin change workaround on irq %d\n", spi->irq);
1373 irq_flags |= IRQF_TRIGGER_RISING;
1374 err = devm_request_threaded_irq(dev, spi->irq,
1375 ads7846_hard_irq, ads7846_irq,
1376 irq_flags, dev->driver->name,
1377 ts);
1378 }
1379
1380 if (err) {
1381 dev_dbg(dev, "irq %d busy?\n", spi->irq);
1382 return err;
1383 }
1384
1385 err = ads784x_hwmon_register(spi, ts);
1386 if (err)
1387 return err;
1388
1389 dev_info(dev, "touchscreen, irq %d\n", spi->irq);
1390
1391 /*
1392 * Take a first sample, leaving nPENIRQ active and vREF off; avoid
1393 * the touchscreen, in case it's not connected.
1394 */
1395 if (ts->model == 7845)
1396 ads7845_read12_ser(dev, PWRDOWN);
1397 else
1398 (void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux));
1399
1400 err = input_register_device(input_dev);
1401 if (err)
1402 return err;
1403
1404 device_init_wakeup(dev, pdata->wakeup);
1405
1406 /*
1407 * If device does not carry platform data we must have allocated it
1408 * when parsing DT data.
1409 */
1410 if (!dev_get_platdata(dev))
1411 devm_kfree(dev, (void *)pdata);
1412
1413 return 0;
1414}
1415
1416static void ads7846_remove(struct spi_device *spi)
1417{
1418 struct ads7846 *ts = spi_get_drvdata(spi);
1419
1420 ads7846_stop(ts);
1421}
1422
1423static struct spi_driver ads7846_driver = {
1424 .driver = {
1425 .name = "ads7846",
1426 .dev_groups = ads784x_groups,
1427 .pm = pm_sleep_ptr(&ads7846_pm),
1428 .of_match_table = ads7846_dt_ids,
1429 },
1430 .probe = ads7846_probe,
1431 .remove = ads7846_remove,
1432 .id_table = ads7846_spi_ids,
1433};
1434
1435module_spi_driver(ads7846_driver);
1436
1437MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1438MODULE_LICENSE("GPL");
1/*
2 * ADS7846 based touchscreen and sensor driver
3 *
4 * Copyright (c) 2005 David Brownell
5 * Copyright (c) 2006 Nokia Corporation
6 * Various changes: Imre Deak <imre.deak@nokia.com>
7 *
8 * Using code from:
9 * - corgi_ts.c
10 * Copyright (C) 2004-2005 Richard Purdie
11 * - omap_ts.[hc], ads7846.h, ts_osk.c
12 * Copyright (C) 2002 MontaVista Software
13 * Copyright (C) 2004 Texas Instruments
14 * Copyright (C) 2005 Dirk Behme
15 *
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License version 2 as
18 * published by the Free Software Foundation.
19 */
20#include <linux/types.h>
21#include <linux/hwmon.h>
22#include <linux/init.h>
23#include <linux/err.h>
24#include <linux/sched.h>
25#include <linux/delay.h>
26#include <linux/input.h>
27#include <linux/interrupt.h>
28#include <linux/slab.h>
29#include <linux/pm.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/irq.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
65struct ts_event {
66 /*
67 * For portability, we can't read 12 bit values using SPI (which
68 * would make the controller deliver them as native byte order u16
69 * with msbs zeroed). Instead, we read them as two 8-bit values,
70 * *** WHICH NEED BYTESWAPPING *** and range adjustment.
71 */
72 u16 x;
73 u16 y;
74 u16 z1, z2;
75 bool ignore;
76 u8 x_buf[3];
77 u8 y_buf[3];
78};
79
80/*
81 * We allocate this separately to avoid cache line sharing issues when
82 * driver is used with DMA-based SPI controllers (like atmel_spi) on
83 * systems where main memory is not DMA-coherent (most non-x86 boards).
84 */
85struct ads7846_packet {
86 u8 read_x, read_y, read_z1, read_z2, pwrdown;
87 u16 dummy; /* for the pwrdown read */
88 struct ts_event tc;
89 /* for ads7845 with mpc5121 psc spi we use 3-byte buffers */
90 u8 read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3];
91};
92
93struct ads7846 {
94 struct input_dev *input;
95 char phys[32];
96 char name[32];
97
98 struct spi_device *spi;
99 struct regulator *reg;
100
101#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
102 struct attribute_group *attr_group;
103 struct device *hwmon;
104#endif
105
106 u16 model;
107 u16 vref_mv;
108 u16 vref_delay_usecs;
109 u16 x_plate_ohms;
110 u16 pressure_max;
111
112 bool swap_xy;
113 bool use_internal;
114
115 struct ads7846_packet *packet;
116
117 struct spi_transfer xfer[18];
118 struct spi_message msg[5];
119 int msg_count;
120 wait_queue_head_t wait;
121
122 bool pendown;
123
124 int read_cnt;
125 int read_rep;
126 int last_read;
127
128 u16 debounce_max;
129 u16 debounce_tol;
130 u16 debounce_rep;
131
132 u16 penirq_recheck_delay_usecs;
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 void (*filter_cleanup)(void *data);
142 int (*get_pendown_state)(void);
143 int gpio_pendown;
144
145 void (*wait_for_sync)(void);
146};
147
148/* leave chip selected when we're done, for quicker re-select? */
149#if 0
150#define CS_CHANGE(xfer) ((xfer).cs_change = 1)
151#else
152#define CS_CHANGE(xfer) ((xfer).cs_change = 0)
153#endif
154
155/*--------------------------------------------------------------------------*/
156
157/* The ADS7846 has touchscreen and other sensors.
158 * Earlier ads784x chips are somewhat compatible.
159 */
160#define ADS_START (1 << 7)
161#define ADS_A2A1A0_d_y (1 << 4) /* differential */
162#define ADS_A2A1A0_d_z1 (3 << 4) /* differential */
163#define ADS_A2A1A0_d_z2 (4 << 4) /* differential */
164#define ADS_A2A1A0_d_x (5 << 4) /* differential */
165#define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */
166#define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */
167#define ADS_A2A1A0_vaux (6 << 4) /* non-differential */
168#define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */
169#define ADS_8_BIT (1 << 3)
170#define ADS_12_BIT (0 << 3)
171#define ADS_SER (1 << 2) /* non-differential */
172#define ADS_DFR (0 << 2) /* differential */
173#define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */
174#define ADS_PD10_ADC_ON (1 << 0) /* ADC on */
175#define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */
176#define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */
177
178#define MAX_12BIT ((1<<12)-1)
179
180/* leave ADC powered up (disables penirq) between differential samples */
181#define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
182 | ADS_12_BIT | ADS_DFR | \
183 (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
184
185#define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref))
186#define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref))
187#define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref))
188
189#define READ_X(vref) (READ_12BIT_DFR(x, 1, vref))
190#define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */
191
192/* single-ended samples need to first power up reference voltage;
193 * we leave both ADC and VREF powered
194 */
195#define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
196 | ADS_12_BIT | ADS_SER)
197
198#define REF_ON (READ_12BIT_DFR(x, 1, 1))
199#define REF_OFF (READ_12BIT_DFR(y, 0, 0))
200
201/* Must be called with ts->lock held */
202static void ads7846_stop(struct ads7846 *ts)
203{
204 if (!ts->disabled && !ts->suspended) {
205 /* Signal IRQ thread to stop polling and disable the handler. */
206 ts->stopped = true;
207 mb();
208 wake_up(&ts->wait);
209 disable_irq(ts->spi->irq);
210 }
211}
212
213/* Must be called with ts->lock held */
214static void ads7846_restart(struct ads7846 *ts)
215{
216 if (!ts->disabled && !ts->suspended) {
217 /* Tell IRQ thread that it may poll the device. */
218 ts->stopped = false;
219 mb();
220 enable_irq(ts->spi->irq);
221 }
222}
223
224/* Must be called with ts->lock held */
225static void __ads7846_disable(struct ads7846 *ts)
226{
227 ads7846_stop(ts);
228 regulator_disable(ts->reg);
229
230 /*
231 * We know the chip's in low power mode since we always
232 * leave it that way after every request
233 */
234}
235
236/* Must be called with ts->lock held */
237static void __ads7846_enable(struct ads7846 *ts)
238{
239 regulator_enable(ts->reg);
240 ads7846_restart(ts);
241}
242
243static void ads7846_disable(struct ads7846 *ts)
244{
245 mutex_lock(&ts->lock);
246
247 if (!ts->disabled) {
248
249 if (!ts->suspended)
250 __ads7846_disable(ts);
251
252 ts->disabled = true;
253 }
254
255 mutex_unlock(&ts->lock);
256}
257
258static void ads7846_enable(struct ads7846 *ts)
259{
260 mutex_lock(&ts->lock);
261
262 if (ts->disabled) {
263
264 ts->disabled = false;
265
266 if (!ts->suspended)
267 __ads7846_enable(ts);
268 }
269
270 mutex_unlock(&ts->lock);
271}
272
273/*--------------------------------------------------------------------------*/
274
275/*
276 * Non-touchscreen sensors only use single-ended conversions.
277 * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
278 * ads7846 lets that pin be unconnected, to use internal vREF.
279 */
280
281struct ser_req {
282 u8 ref_on;
283 u8 command;
284 u8 ref_off;
285 u16 scratch;
286 struct spi_message msg;
287 struct spi_transfer xfer[6];
288 /*
289 * DMA (thus cache coherency maintenance) requires the
290 * transfer buffers to live in their own cache lines.
291 */
292 __be16 sample ____cacheline_aligned;
293};
294
295struct ads7845_ser_req {
296 u8 command[3];
297 struct spi_message msg;
298 struct spi_transfer xfer[2];
299 /*
300 * DMA (thus cache coherency maintenance) requires the
301 * transfer buffers to live in their own cache lines.
302 */
303 u8 sample[3] ____cacheline_aligned;
304};
305
306static int ads7846_read12_ser(struct device *dev, unsigned command)
307{
308 struct spi_device *spi = to_spi_device(dev);
309 struct ads7846 *ts = dev_get_drvdata(dev);
310 struct ser_req *req;
311 int status;
312
313 req = kzalloc(sizeof *req, GFP_KERNEL);
314 if (!req)
315 return -ENOMEM;
316
317 spi_message_init(&req->msg);
318
319 /* maybe turn on internal vREF, and let it settle */
320 if (ts->use_internal) {
321 req->ref_on = REF_ON;
322 req->xfer[0].tx_buf = &req->ref_on;
323 req->xfer[0].len = 1;
324 spi_message_add_tail(&req->xfer[0], &req->msg);
325
326 req->xfer[1].rx_buf = &req->scratch;
327 req->xfer[1].len = 2;
328
329 /* for 1uF, settle for 800 usec; no cap, 100 usec. */
330 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
331 spi_message_add_tail(&req->xfer[1], &req->msg);
332
333 /* Enable reference voltage */
334 command |= ADS_PD10_REF_ON;
335 }
336
337 /* Enable ADC in every case */
338 command |= ADS_PD10_ADC_ON;
339
340 /* take sample */
341 req->command = (u8) command;
342 req->xfer[2].tx_buf = &req->command;
343 req->xfer[2].len = 1;
344 spi_message_add_tail(&req->xfer[2], &req->msg);
345
346 req->xfer[3].rx_buf = &req->sample;
347 req->xfer[3].len = 2;
348 spi_message_add_tail(&req->xfer[3], &req->msg);
349
350 /* REVISIT: take a few more samples, and compare ... */
351
352 /* converter in low power mode & enable PENIRQ */
353 req->ref_off = PWRDOWN;
354 req->xfer[4].tx_buf = &req->ref_off;
355 req->xfer[4].len = 1;
356 spi_message_add_tail(&req->xfer[4], &req->msg);
357
358 req->xfer[5].rx_buf = &req->scratch;
359 req->xfer[5].len = 2;
360 CS_CHANGE(req->xfer[5]);
361 spi_message_add_tail(&req->xfer[5], &req->msg);
362
363 mutex_lock(&ts->lock);
364 ads7846_stop(ts);
365 status = spi_sync(spi, &req->msg);
366 ads7846_restart(ts);
367 mutex_unlock(&ts->lock);
368
369 if (status == 0) {
370 /* on-wire is a must-ignore bit, a BE12 value, then padding */
371 status = be16_to_cpu(req->sample);
372 status = status >> 3;
373 status &= 0x0fff;
374 }
375
376 kfree(req);
377 return status;
378}
379
380static int ads7845_read12_ser(struct device *dev, unsigned command)
381{
382 struct spi_device *spi = to_spi_device(dev);
383 struct ads7846 *ts = dev_get_drvdata(dev);
384 struct ads7845_ser_req *req;
385 int status;
386
387 req = kzalloc(sizeof *req, GFP_KERNEL);
388 if (!req)
389 return -ENOMEM;
390
391 spi_message_init(&req->msg);
392
393 req->command[0] = (u8) command;
394 req->xfer[0].tx_buf = req->command;
395 req->xfer[0].rx_buf = req->sample;
396 req->xfer[0].len = 3;
397 spi_message_add_tail(&req->xfer[0], &req->msg);
398
399 mutex_lock(&ts->lock);
400 ads7846_stop(ts);
401 status = spi_sync(spi, &req->msg);
402 ads7846_restart(ts);
403 mutex_unlock(&ts->lock);
404
405 if (status == 0) {
406 /* BE12 value, then padding */
407 status = be16_to_cpu(*((u16 *)&req->sample[1]));
408 status = status >> 3;
409 status &= 0x0fff;
410 }
411
412 kfree(req);
413 return status;
414}
415
416#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
417
418#define SHOW(name, var, adjust) static ssize_t \
419name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
420{ \
421 struct ads7846 *ts = dev_get_drvdata(dev); \
422 ssize_t v = ads7846_read12_ser(dev, \
423 READ_12BIT_SER(var)); \
424 if (v < 0) \
425 return v; \
426 return sprintf(buf, "%u\n", adjust(ts, v)); \
427} \
428static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
429
430
431/* Sysfs conventions report temperatures in millidegrees Celsius.
432 * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
433 * accuracy scheme without calibration data. For now we won't try either;
434 * userspace sees raw sensor values, and must scale/calibrate appropriately.
435 */
436static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
437{
438 return v;
439}
440
441SHOW(temp0, temp0, null_adjust) /* temp1_input */
442SHOW(temp1, temp1, null_adjust) /* temp2_input */
443
444
445/* sysfs conventions report voltages in millivolts. We can convert voltages
446 * if we know vREF. userspace may need to scale vAUX to match the board's
447 * external resistors; we assume that vBATT only uses the internal ones.
448 */
449static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
450{
451 unsigned retval = v;
452
453 /* external resistors may scale vAUX into 0..vREF */
454 retval *= ts->vref_mv;
455 retval = retval >> 12;
456
457 return retval;
458}
459
460static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
461{
462 unsigned retval = vaux_adjust(ts, v);
463
464 /* ads7846 has a resistor ladder to scale this signal down */
465 if (ts->model == 7846)
466 retval *= 4;
467
468 return retval;
469}
470
471SHOW(in0_input, vaux, vaux_adjust)
472SHOW(in1_input, vbatt, vbatt_adjust)
473
474static struct attribute *ads7846_attributes[] = {
475 &dev_attr_temp0.attr,
476 &dev_attr_temp1.attr,
477 &dev_attr_in0_input.attr,
478 &dev_attr_in1_input.attr,
479 NULL,
480};
481
482static struct attribute_group ads7846_attr_group = {
483 .attrs = ads7846_attributes,
484};
485
486static struct attribute *ads7843_attributes[] = {
487 &dev_attr_in0_input.attr,
488 &dev_attr_in1_input.attr,
489 NULL,
490};
491
492static struct attribute_group ads7843_attr_group = {
493 .attrs = ads7843_attributes,
494};
495
496static struct attribute *ads7845_attributes[] = {
497 &dev_attr_in0_input.attr,
498 NULL,
499};
500
501static struct attribute_group ads7845_attr_group = {
502 .attrs = ads7845_attributes,
503};
504
505static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
506{
507 struct device *hwmon;
508 int err;
509
510 /* hwmon sensors need a reference voltage */
511 switch (ts->model) {
512 case 7846:
513 if (!ts->vref_mv) {
514 dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
515 ts->vref_mv = 2500;
516 ts->use_internal = true;
517 }
518 break;
519 case 7845:
520 case 7843:
521 if (!ts->vref_mv) {
522 dev_warn(&spi->dev,
523 "external vREF for ADS%d not specified\n",
524 ts->model);
525 return 0;
526 }
527 break;
528 }
529
530 /* different chips have different sensor groups */
531 switch (ts->model) {
532 case 7846:
533 ts->attr_group = &ads7846_attr_group;
534 break;
535 case 7845:
536 ts->attr_group = &ads7845_attr_group;
537 break;
538 case 7843:
539 ts->attr_group = &ads7843_attr_group;
540 break;
541 default:
542 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
543 return 0;
544 }
545
546 err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
547 if (err)
548 return err;
549
550 hwmon = hwmon_device_register(&spi->dev);
551 if (IS_ERR(hwmon)) {
552 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
553 return PTR_ERR(hwmon);
554 }
555
556 ts->hwmon = hwmon;
557 return 0;
558}
559
560static void ads784x_hwmon_unregister(struct spi_device *spi,
561 struct ads7846 *ts)
562{
563 if (ts->hwmon) {
564 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
565 hwmon_device_unregister(ts->hwmon);
566 }
567}
568
569#else
570static inline int ads784x_hwmon_register(struct spi_device *spi,
571 struct ads7846 *ts)
572{
573 return 0;
574}
575
576static inline void ads784x_hwmon_unregister(struct spi_device *spi,
577 struct ads7846 *ts)
578{
579}
580#endif
581
582static ssize_t ads7846_pen_down_show(struct device *dev,
583 struct device_attribute *attr, char *buf)
584{
585 struct ads7846 *ts = dev_get_drvdata(dev);
586
587 return sprintf(buf, "%u\n", ts->pendown);
588}
589
590static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
591
592static ssize_t ads7846_disable_show(struct device *dev,
593 struct device_attribute *attr, char *buf)
594{
595 struct ads7846 *ts = dev_get_drvdata(dev);
596
597 return sprintf(buf, "%u\n", ts->disabled);
598}
599
600static ssize_t ads7846_disable_store(struct device *dev,
601 struct device_attribute *attr,
602 const char *buf, size_t count)
603{
604 struct ads7846 *ts = dev_get_drvdata(dev);
605 unsigned int i;
606 int err;
607
608 err = kstrtouint(buf, 10, &i);
609 if (err)
610 return err;
611
612 if (i)
613 ads7846_disable(ts);
614 else
615 ads7846_enable(ts);
616
617 return count;
618}
619
620static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
621
622static struct attribute *ads784x_attributes[] = {
623 &dev_attr_pen_down.attr,
624 &dev_attr_disable.attr,
625 NULL,
626};
627
628static struct attribute_group ads784x_attr_group = {
629 .attrs = ads784x_attributes,
630};
631
632/*--------------------------------------------------------------------------*/
633
634static int get_pendown_state(struct ads7846 *ts)
635{
636 if (ts->get_pendown_state)
637 return ts->get_pendown_state();
638
639 return !gpio_get_value(ts->gpio_pendown);
640}
641
642static void null_wait_for_sync(void)
643{
644}
645
646static 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
688static int ads7846_no_filter(void *ads, int data_idx, int *val)
689{
690 return ADS7846_FILTER_OK;
691}
692
693static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m)
694{
695 struct spi_transfer *t =
696 list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
697
698 if (ts->model == 7845) {
699 return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3;
700 } else {
701 /*
702 * adjust: on-wire is a must-ignore bit, a BE12 value, then
703 * padding; built from two 8 bit values written msb-first.
704 */
705 return be16_to_cpup((__be16 *)t->rx_buf) >> 3;
706 }
707}
708
709static void ads7846_update_value(struct spi_message *m, int val)
710{
711 struct spi_transfer *t =
712 list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
713
714 *(u16 *)t->rx_buf = val;
715}
716
717static void ads7846_read_state(struct ads7846 *ts)
718{
719 struct ads7846_packet *packet = ts->packet;
720 struct spi_message *m;
721 int msg_idx = 0;
722 int val;
723 int action;
724 int error;
725
726 while (msg_idx < ts->msg_count) {
727
728 ts->wait_for_sync();
729
730 m = &ts->msg[msg_idx];
731 error = spi_sync(ts->spi, m);
732 if (error) {
733 dev_err(&ts->spi->dev, "spi_async --> %d\n", error);
734 packet->tc.ignore = true;
735 return;
736 }
737
738 /*
739 * Last message is power down request, no need to convert
740 * or filter the value.
741 */
742 if (msg_idx < ts->msg_count - 1) {
743
744 val = ads7846_get_value(ts, m);
745
746 action = ts->filter(ts->filter_data, msg_idx, &val);
747 switch (action) {
748 case ADS7846_FILTER_REPEAT:
749 continue;
750
751 case ADS7846_FILTER_IGNORE:
752 packet->tc.ignore = true;
753 msg_idx = ts->msg_count - 1;
754 continue;
755
756 case ADS7846_FILTER_OK:
757 ads7846_update_value(m, val);
758 packet->tc.ignore = false;
759 msg_idx++;
760 break;
761
762 default:
763 BUG();
764 }
765 } else {
766 msg_idx++;
767 }
768 }
769}
770
771static void ads7846_report_state(struct ads7846 *ts)
772{
773 struct ads7846_packet *packet = ts->packet;
774 unsigned int Rt;
775 u16 x, y, z1, z2;
776
777 /*
778 * ads7846_get_value() does in-place conversion (including byte swap)
779 * from on-the-wire format as part of debouncing to get stable
780 * readings.
781 */
782 if (ts->model == 7845) {
783 x = *(u16 *)packet->tc.x_buf;
784 y = *(u16 *)packet->tc.y_buf;
785 z1 = 0;
786 z2 = 0;
787 } else {
788 x = packet->tc.x;
789 y = packet->tc.y;
790 z1 = packet->tc.z1;
791 z2 = packet->tc.z2;
792 }
793
794 /* range filtering */
795 if (x == MAX_12BIT)
796 x = 0;
797
798 if (ts->model == 7843) {
799 Rt = ts->pressure_max / 2;
800 } else if (ts->model == 7845) {
801 if (get_pendown_state(ts))
802 Rt = ts->pressure_max / 2;
803 else
804 Rt = 0;
805 dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt);
806 } else if (likely(x && z1)) {
807 /* compute touch pressure resistance using equation #2 */
808 Rt = z2;
809 Rt -= z1;
810 Rt *= x;
811 Rt *= ts->x_plate_ohms;
812 Rt /= z1;
813 Rt = (Rt + 2047) >> 12;
814 } else {
815 Rt = 0;
816 }
817
818 /*
819 * Sample found inconsistent by debouncing or pressure is beyond
820 * the maximum. Don't report it to user space, repeat at least
821 * once more the measurement
822 */
823 if (packet->tc.ignore || Rt > ts->pressure_max) {
824 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
825 packet->tc.ignore, Rt);
826 return;
827 }
828
829 /*
830 * Maybe check the pendown state before reporting. This discards
831 * false readings when the pen is lifted.
832 */
833 if (ts->penirq_recheck_delay_usecs) {
834 udelay(ts->penirq_recheck_delay_usecs);
835 if (!get_pendown_state(ts))
836 Rt = 0;
837 }
838
839 /*
840 * NOTE: We can't rely on the pressure to determine the pen down
841 * state, even this controller has a pressure sensor. The pressure
842 * value can fluctuate for quite a while after lifting the pen and
843 * in some cases may not even settle at the expected value.
844 *
845 * The only safe way to check for the pen up condition is in the
846 * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
847 */
848 if (Rt) {
849 struct input_dev *input = ts->input;
850
851 if (ts->swap_xy)
852 swap(x, y);
853
854 if (!ts->pendown) {
855 input_report_key(input, BTN_TOUCH, 1);
856 ts->pendown = true;
857 dev_vdbg(&ts->spi->dev, "DOWN\n");
858 }
859
860 input_report_abs(input, ABS_X, x);
861 input_report_abs(input, ABS_Y, y);
862 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
863
864 input_sync(input);
865 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
866 }
867}
868
869static irqreturn_t ads7846_hard_irq(int irq, void *handle)
870{
871 struct ads7846 *ts = handle;
872
873 return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
874}
875
876
877static irqreturn_t ads7846_irq(int irq, void *handle)
878{
879 struct ads7846 *ts = handle;
880
881 /* Start with a small delay before checking pendown state */
882 msleep(TS_POLL_DELAY);
883
884 while (!ts->stopped && get_pendown_state(ts)) {
885
886 /* pen is down, continue with the measurement */
887 ads7846_read_state(ts);
888
889 if (!ts->stopped)
890 ads7846_report_state(ts);
891
892 wait_event_timeout(ts->wait, ts->stopped,
893 msecs_to_jiffies(TS_POLL_PERIOD));
894 }
895
896 if (ts->pendown) {
897 struct input_dev *input = ts->input;
898
899 input_report_key(input, BTN_TOUCH, 0);
900 input_report_abs(input, ABS_PRESSURE, 0);
901 input_sync(input);
902
903 ts->pendown = false;
904 dev_vdbg(&ts->spi->dev, "UP\n");
905 }
906
907 return IRQ_HANDLED;
908}
909
910#ifdef CONFIG_PM_SLEEP
911static int ads7846_suspend(struct device *dev)
912{
913 struct ads7846 *ts = dev_get_drvdata(dev);
914
915 mutex_lock(&ts->lock);
916
917 if (!ts->suspended) {
918
919 if (!ts->disabled)
920 __ads7846_disable(ts);
921
922 if (device_may_wakeup(&ts->spi->dev))
923 enable_irq_wake(ts->spi->irq);
924
925 ts->suspended = true;
926 }
927
928 mutex_unlock(&ts->lock);
929
930 return 0;
931}
932
933static int ads7846_resume(struct device *dev)
934{
935 struct ads7846 *ts = dev_get_drvdata(dev);
936
937 mutex_lock(&ts->lock);
938
939 if (ts->suspended) {
940
941 ts->suspended = false;
942
943 if (device_may_wakeup(&ts->spi->dev))
944 disable_irq_wake(ts->spi->irq);
945
946 if (!ts->disabled)
947 __ads7846_enable(ts);
948 }
949
950 mutex_unlock(&ts->lock);
951
952 return 0;
953}
954#endif
955
956static SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
957
958static int __devinit ads7846_setup_pendown(struct spi_device *spi, struct ads7846 *ts)
959{
960 struct ads7846_platform_data *pdata = spi->dev.platform_data;
961 int err;
962
963 /*
964 * REVISIT when the irq can be triggered active-low, or if for some
965 * reason the touchscreen isn't hooked up, we don't need to access
966 * the pendown state.
967 */
968
969 if (pdata->get_pendown_state) {
970 ts->get_pendown_state = pdata->get_pendown_state;
971 } else if (gpio_is_valid(pdata->gpio_pendown)) {
972
973 err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN,
974 "ads7846_pendown");
975 if (err) {
976 dev_err(&spi->dev,
977 "failed to request/setup pendown GPIO%d: %d\n",
978 pdata->gpio_pendown, err);
979 return err;
980 }
981
982 ts->gpio_pendown = pdata->gpio_pendown;
983
984 } else {
985 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
986 return -EINVAL;
987 }
988
989 return 0;
990}
991
992/*
993 * Set up the transfers to read touchscreen state; this assumes we
994 * use formula #2 for pressure, not #3.
995 */
996static void __devinit ads7846_setup_spi_msg(struct ads7846 *ts,
997 const struct ads7846_platform_data *pdata)
998{
999 struct spi_message *m = &ts->msg[0];
1000 struct spi_transfer *x = ts->xfer;
1001 struct ads7846_packet *packet = ts->packet;
1002 int vref = pdata->keep_vref_on;
1003
1004 if (ts->model == 7873) {
1005 /*
1006 * The AD7873 is almost identical to the ADS7846
1007 * keep VREF off during differential/ratiometric
1008 * conversion modes.
1009 */
1010 ts->model = 7846;
1011 vref = 0;
1012 }
1013
1014 ts->msg_count = 1;
1015 spi_message_init(m);
1016 m->context = ts;
1017
1018 if (ts->model == 7845) {
1019 packet->read_y_cmd[0] = READ_Y(vref);
1020 packet->read_y_cmd[1] = 0;
1021 packet->read_y_cmd[2] = 0;
1022 x->tx_buf = &packet->read_y_cmd[0];
1023 x->rx_buf = &packet->tc.y_buf[0];
1024 x->len = 3;
1025 spi_message_add_tail(x, m);
1026 } else {
1027 /* y- still on; turn on only y+ (and ADC) */
1028 packet->read_y = READ_Y(vref);
1029 x->tx_buf = &packet->read_y;
1030 x->len = 1;
1031 spi_message_add_tail(x, m);
1032
1033 x++;
1034 x->rx_buf = &packet->tc.y;
1035 x->len = 2;
1036 spi_message_add_tail(x, m);
1037 }
1038
1039 /*
1040 * The first sample after switching drivers can be low quality;
1041 * optionally discard it, using a second one after the signals
1042 * have had enough time to stabilize.
1043 */
1044 if (pdata->settle_delay_usecs) {
1045 x->delay_usecs = pdata->settle_delay_usecs;
1046
1047 x++;
1048 x->tx_buf = &packet->read_y;
1049 x->len = 1;
1050 spi_message_add_tail(x, m);
1051
1052 x++;
1053 x->rx_buf = &packet->tc.y;
1054 x->len = 2;
1055 spi_message_add_tail(x, m);
1056 }
1057
1058 ts->msg_count++;
1059 m++;
1060 spi_message_init(m);
1061 m->context = ts;
1062
1063 if (ts->model == 7845) {
1064 x++;
1065 packet->read_x_cmd[0] = READ_X(vref);
1066 packet->read_x_cmd[1] = 0;
1067 packet->read_x_cmd[2] = 0;
1068 x->tx_buf = &packet->read_x_cmd[0];
1069 x->rx_buf = &packet->tc.x_buf[0];
1070 x->len = 3;
1071 spi_message_add_tail(x, m);
1072 } else {
1073 /* turn y- off, x+ on, then leave in lowpower */
1074 x++;
1075 packet->read_x = READ_X(vref);
1076 x->tx_buf = &packet->read_x;
1077 x->len = 1;
1078 spi_message_add_tail(x, m);
1079
1080 x++;
1081 x->rx_buf = &packet->tc.x;
1082 x->len = 2;
1083 spi_message_add_tail(x, m);
1084 }
1085
1086 /* ... maybe discard first sample ... */
1087 if (pdata->settle_delay_usecs) {
1088 x->delay_usecs = pdata->settle_delay_usecs;
1089
1090 x++;
1091 x->tx_buf = &packet->read_x;
1092 x->len = 1;
1093 spi_message_add_tail(x, m);
1094
1095 x++;
1096 x->rx_buf = &packet->tc.x;
1097 x->len = 2;
1098 spi_message_add_tail(x, m);
1099 }
1100
1101 /* turn y+ off, x- on; we'll use formula #2 */
1102 if (ts->model == 7846) {
1103 ts->msg_count++;
1104 m++;
1105 spi_message_init(m);
1106 m->context = ts;
1107
1108 x++;
1109 packet->read_z1 = READ_Z1(vref);
1110 x->tx_buf = &packet->read_z1;
1111 x->len = 1;
1112 spi_message_add_tail(x, m);
1113
1114 x++;
1115 x->rx_buf = &packet->tc.z1;
1116 x->len = 2;
1117 spi_message_add_tail(x, m);
1118
1119 /* ... maybe discard first sample ... */
1120 if (pdata->settle_delay_usecs) {
1121 x->delay_usecs = pdata->settle_delay_usecs;
1122
1123 x++;
1124 x->tx_buf = &packet->read_z1;
1125 x->len = 1;
1126 spi_message_add_tail(x, m);
1127
1128 x++;
1129 x->rx_buf = &packet->tc.z1;
1130 x->len = 2;
1131 spi_message_add_tail(x, m);
1132 }
1133
1134 ts->msg_count++;
1135 m++;
1136 spi_message_init(m);
1137 m->context = ts;
1138
1139 x++;
1140 packet->read_z2 = READ_Z2(vref);
1141 x->tx_buf = &packet->read_z2;
1142 x->len = 1;
1143 spi_message_add_tail(x, m);
1144
1145 x++;
1146 x->rx_buf = &packet->tc.z2;
1147 x->len = 2;
1148 spi_message_add_tail(x, m);
1149
1150 /* ... maybe discard first sample ... */
1151 if (pdata->settle_delay_usecs) {
1152 x->delay_usecs = pdata->settle_delay_usecs;
1153
1154 x++;
1155 x->tx_buf = &packet->read_z2;
1156 x->len = 1;
1157 spi_message_add_tail(x, m);
1158
1159 x++;
1160 x->rx_buf = &packet->tc.z2;
1161 x->len = 2;
1162 spi_message_add_tail(x, m);
1163 }
1164 }
1165
1166 /* power down */
1167 ts->msg_count++;
1168 m++;
1169 spi_message_init(m);
1170 m->context = ts;
1171
1172 if (ts->model == 7845) {
1173 x++;
1174 packet->pwrdown_cmd[0] = PWRDOWN;
1175 packet->pwrdown_cmd[1] = 0;
1176 packet->pwrdown_cmd[2] = 0;
1177 x->tx_buf = &packet->pwrdown_cmd[0];
1178 x->len = 3;
1179 } else {
1180 x++;
1181 packet->pwrdown = PWRDOWN;
1182 x->tx_buf = &packet->pwrdown;
1183 x->len = 1;
1184 spi_message_add_tail(x, m);
1185
1186 x++;
1187 x->rx_buf = &packet->dummy;
1188 x->len = 2;
1189 }
1190
1191 CS_CHANGE(*x);
1192 spi_message_add_tail(x, m);
1193}
1194
1195static int __devinit ads7846_probe(struct spi_device *spi)
1196{
1197 struct ads7846 *ts;
1198 struct ads7846_packet *packet;
1199 struct input_dev *input_dev;
1200 struct ads7846_platform_data *pdata = spi->dev.platform_data;
1201 unsigned long irq_flags;
1202 int err;
1203
1204 if (!spi->irq) {
1205 dev_dbg(&spi->dev, "no IRQ?\n");
1206 return -ENODEV;
1207 }
1208
1209 if (!pdata) {
1210 dev_dbg(&spi->dev, "no platform data?\n");
1211 return -ENODEV;
1212 }
1213
1214 /* don't exceed max specified sample rate */
1215 if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
1216 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
1217 (spi->max_speed_hz/SAMPLE_BITS)/1000);
1218 return -EINVAL;
1219 }
1220
1221 /* We'd set TX word size 8 bits and RX word size to 13 bits ... except
1222 * that even if the hardware can do that, the SPI controller driver
1223 * may not. So we stick to very-portable 8 bit words, both RX and TX.
1224 */
1225 spi->bits_per_word = 8;
1226 spi->mode = SPI_MODE_0;
1227 err = spi_setup(spi);
1228 if (err < 0)
1229 return err;
1230
1231 ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
1232 packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
1233 input_dev = input_allocate_device();
1234 if (!ts || !packet || !input_dev) {
1235 err = -ENOMEM;
1236 goto err_free_mem;
1237 }
1238
1239 dev_set_drvdata(&spi->dev, ts);
1240
1241 ts->packet = packet;
1242 ts->spi = spi;
1243 ts->input = input_dev;
1244 ts->vref_mv = pdata->vref_mv;
1245 ts->swap_xy = pdata->swap_xy;
1246
1247 mutex_init(&ts->lock);
1248 init_waitqueue_head(&ts->wait);
1249
1250 ts->model = pdata->model ? : 7846;
1251 ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
1252 ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
1253 ts->pressure_max = pdata->pressure_max ? : ~0;
1254
1255 if (pdata->filter != NULL) {
1256 if (pdata->filter_init != NULL) {
1257 err = pdata->filter_init(pdata, &ts->filter_data);
1258 if (err < 0)
1259 goto err_free_mem;
1260 }
1261 ts->filter = pdata->filter;
1262 ts->filter_cleanup = pdata->filter_cleanup;
1263 } else if (pdata->debounce_max) {
1264 ts->debounce_max = pdata->debounce_max;
1265 if (ts->debounce_max < 2)
1266 ts->debounce_max = 2;
1267 ts->debounce_tol = pdata->debounce_tol;
1268 ts->debounce_rep = pdata->debounce_rep;
1269 ts->filter = ads7846_debounce_filter;
1270 ts->filter_data = ts;
1271 } else {
1272 ts->filter = ads7846_no_filter;
1273 }
1274
1275 err = ads7846_setup_pendown(spi, ts);
1276 if (err)
1277 goto err_cleanup_filter;
1278
1279 if (pdata->penirq_recheck_delay_usecs)
1280 ts->penirq_recheck_delay_usecs =
1281 pdata->penirq_recheck_delay_usecs;
1282
1283 ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
1284
1285 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
1286 snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
1287
1288 input_dev->name = ts->name;
1289 input_dev->phys = ts->phys;
1290 input_dev->dev.parent = &spi->dev;
1291
1292 input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
1293 input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
1294 input_set_abs_params(input_dev, ABS_X,
1295 pdata->x_min ? : 0,
1296 pdata->x_max ? : MAX_12BIT,
1297 0, 0);
1298 input_set_abs_params(input_dev, ABS_Y,
1299 pdata->y_min ? : 0,
1300 pdata->y_max ? : MAX_12BIT,
1301 0, 0);
1302 input_set_abs_params(input_dev, ABS_PRESSURE,
1303 pdata->pressure_min, pdata->pressure_max, 0, 0);
1304
1305 ads7846_setup_spi_msg(ts, pdata);
1306
1307 ts->reg = regulator_get(&spi->dev, "vcc");
1308 if (IS_ERR(ts->reg)) {
1309 err = PTR_ERR(ts->reg);
1310 dev_err(&spi->dev, "unable to get regulator: %d\n", err);
1311 goto err_free_gpio;
1312 }
1313
1314 err = regulator_enable(ts->reg);
1315 if (err) {
1316 dev_err(&spi->dev, "unable to enable regulator: %d\n", err);
1317 goto err_put_regulator;
1318 }
1319
1320 irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
1321 irq_flags |= IRQF_ONESHOT;
1322
1323 err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq,
1324 irq_flags, spi->dev.driver->name, ts);
1325 if (err && !pdata->irq_flags) {
1326 dev_info(&spi->dev,
1327 "trying pin change workaround on irq %d\n", spi->irq);
1328 irq_flags |= IRQF_TRIGGER_RISING;
1329 err = request_threaded_irq(spi->irq,
1330 ads7846_hard_irq, ads7846_irq,
1331 irq_flags, spi->dev.driver->name, ts);
1332 }
1333
1334 if (err) {
1335 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1336 goto err_disable_regulator;
1337 }
1338
1339 err = ads784x_hwmon_register(spi, ts);
1340 if (err)
1341 goto err_free_irq;
1342
1343 dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1344
1345 /*
1346 * Take a first sample, leaving nPENIRQ active and vREF off; avoid
1347 * the touchscreen, in case it's not connected.
1348 */
1349 if (ts->model == 7845)
1350 ads7845_read12_ser(&spi->dev, PWRDOWN);
1351 else
1352 (void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux));
1353
1354 err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1355 if (err)
1356 goto err_remove_hwmon;
1357
1358 err = input_register_device(input_dev);
1359 if (err)
1360 goto err_remove_attr_group;
1361
1362 device_init_wakeup(&spi->dev, pdata->wakeup);
1363
1364 return 0;
1365
1366 err_remove_attr_group:
1367 sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1368 err_remove_hwmon:
1369 ads784x_hwmon_unregister(spi, ts);
1370 err_free_irq:
1371 free_irq(spi->irq, ts);
1372 err_disable_regulator:
1373 regulator_disable(ts->reg);
1374 err_put_regulator:
1375 regulator_put(ts->reg);
1376 err_free_gpio:
1377 if (!ts->get_pendown_state)
1378 gpio_free(ts->gpio_pendown);
1379 err_cleanup_filter:
1380 if (ts->filter_cleanup)
1381 ts->filter_cleanup(ts->filter_data);
1382 err_free_mem:
1383 input_free_device(input_dev);
1384 kfree(packet);
1385 kfree(ts);
1386 return err;
1387}
1388
1389static int __devexit ads7846_remove(struct spi_device *spi)
1390{
1391 struct ads7846 *ts = dev_get_drvdata(&spi->dev);
1392
1393 device_init_wakeup(&spi->dev, false);
1394
1395 sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1396
1397 ads7846_disable(ts);
1398 free_irq(ts->spi->irq, ts);
1399
1400 input_unregister_device(ts->input);
1401
1402 ads784x_hwmon_unregister(spi, ts);
1403
1404 regulator_disable(ts->reg);
1405 regulator_put(ts->reg);
1406
1407 if (!ts->get_pendown_state) {
1408 /*
1409 * If we are not using specialized pendown method we must
1410 * have been relying on gpio we set up ourselves.
1411 */
1412 gpio_free(ts->gpio_pendown);
1413 }
1414
1415 if (ts->filter_cleanup)
1416 ts->filter_cleanup(ts->filter_data);
1417
1418 kfree(ts->packet);
1419 kfree(ts);
1420
1421 dev_dbg(&spi->dev, "unregistered touchscreen\n");
1422
1423 return 0;
1424}
1425
1426static struct spi_driver ads7846_driver = {
1427 .driver = {
1428 .name = "ads7846",
1429 .owner = THIS_MODULE,
1430 .pm = &ads7846_pm,
1431 },
1432 .probe = ads7846_probe,
1433 .remove = __devexit_p(ads7846_remove),
1434};
1435
1436module_spi_driver(ads7846_driver);
1437
1438MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1439MODULE_LICENSE("GPL");
1440MODULE_ALIAS("spi:ads7846");