Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[sfrench/cifs-2.6.git] / drivers / input / touchscreen / ads7846.c
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/hwmon.h>
21 #include <linux/init.h>
22 #include <linux/err.h>
23 #include <linux/delay.h>
24 #include <linux/input.h>
25 #include <linux/interrupt.h>
26 #include <linux/slab.h>
27 #include <linux/gpio.h>
28 #include <linux/spi/spi.h>
29 #include <linux/spi/ads7846.h>
30 #include <asm/irq.h>
31
32
33 /*
34  * This code has been heavily tested on a Nokia 770, and lightly
35  * tested on other ads7846 devices (OSK/Mistral, Lubbock).
36  * TSC2046 is just newer ads7846 silicon.
37  * Support for ads7843 tested on Atmel at91sam926x-EK.
38  * Support for ads7845 has only been stubbed in.
39  *
40  * IRQ handling needs a workaround because of a shortcoming in handling
41  * edge triggered IRQs on some platforms like the OMAP1/2. These
42  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
43  * have to maintain our own SW IRQ disabled status. This should be
44  * removed as soon as the affected platform's IRQ handling is fixed.
45  *
46  * app note sbaa036 talks in more detail about accurate sampling...
47  * that ought to help in situations like LCDs inducing noise (which
48  * can also be helped by using synch signals) and more generally.
49  * This driver tries to utilize the measures described in the app
50  * note. The strength of filtering can be set in the board-* specific
51  * files.
52  */
53
54 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
55 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
56
57 /* this driver doesn't aim at the peak continuous sample rate */
58 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
59
60 struct ts_event {
61         /* For portability, we can't read 12 bit values using SPI (which
62          * would make the controller deliver them as native byteorder u16
63          * with msbs zeroed).  Instead, we read them as two 8-bit values,
64          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
65          */
66         u16     x;
67         u16     y;
68         u16     z1, z2;
69         int     ignore;
70 };
71
72 /*
73  * We allocate this separately to avoid cache line sharing issues when
74  * driver is used with DMA-based SPI controllers (like atmel_spi) on
75  * systems where main memory is not DMA-coherent (most non-x86 boards).
76  */
77 struct ads7846_packet {
78         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
79         u16                     dummy;          /* for the pwrdown read */
80         struct ts_event         tc;
81 };
82
83 struct ads7846 {
84         struct input_dev        *input;
85         char                    phys[32];
86
87         struct spi_device       *spi;
88
89 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
90         struct attribute_group  *attr_group;
91         struct device           *hwmon;
92 #endif
93
94         u16                     model;
95         u16                     vref_mv;
96         u16                     vref_delay_usecs;
97         u16                     x_plate_ohms;
98         u16                     pressure_max;
99
100         struct ads7846_packet   *packet;
101
102         struct spi_transfer     xfer[18];
103         struct spi_message      msg[5];
104         struct spi_message      *last_msg;
105         int                     msg_idx;
106         int                     read_cnt;
107         int                     read_rep;
108         int                     last_read;
109
110         u16                     debounce_max;
111         u16                     debounce_tol;
112         u16                     debounce_rep;
113
114         u16                     penirq_recheck_delay_usecs;
115
116         spinlock_t              lock;
117         struct hrtimer          timer;
118         unsigned                pendown:1;      /* P: lock */
119         unsigned                pending:1;      /* P: lock */
120 // FIXME remove "irq_disabled"
121         unsigned                irq_disabled:1; /* P: lock */
122         unsigned                disabled:1;
123         unsigned                is_suspended:1;
124
125         int                     (*filter)(void *data, int data_idx, int *val);
126         void                    *filter_data;
127         void                    (*filter_cleanup)(void *data);
128         int                     (*get_pendown_state)(void);
129         int                     gpio_pendown;
130 };
131
132 /* leave chip selected when we're done, for quicker re-select? */
133 #if     0
134 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
135 #else
136 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
137 #endif
138
139 /*--------------------------------------------------------------------------*/
140
141 /* The ADS7846 has touchscreen and other sensors.
142  * Earlier ads784x chips are somewhat compatible.
143  */
144 #define ADS_START               (1 << 7)
145 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
146 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
147 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
148 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
149 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
150 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
151 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
152 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
153 #define ADS_8_BIT               (1 << 3)
154 #define ADS_12_BIT              (0 << 3)
155 #define ADS_SER                 (1 << 2)        /* non-differential */
156 #define ADS_DFR                 (0 << 2)        /* differential */
157 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
158 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
159 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
160 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
161
162 #define MAX_12BIT       ((1<<12)-1)
163
164 /* leave ADC powered up (disables penirq) between differential samples */
165 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
166         | ADS_12_BIT | ADS_DFR | \
167         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
168
169 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
170 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
171 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
172
173 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
174 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
175
176 /* single-ended samples need to first power up reference voltage;
177  * we leave both ADC and VREF powered
178  */
179 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
180         | ADS_12_BIT | ADS_SER)
181
182 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
183 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
184
185 /*--------------------------------------------------------------------------*/
186
187 /*
188  * Non-touchscreen sensors only use single-ended conversions.
189  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
190  * ads7846 lets that pin be unconnected, to use internal vREF.
191  */
192
193 struct ser_req {
194         u8                      ref_on;
195         u8                      command;
196         u8                      ref_off;
197         u16                     scratch;
198         __be16                  sample;
199         struct spi_message      msg;
200         struct spi_transfer     xfer[6];
201 };
202
203 static void ads7846_enable(struct ads7846 *ts);
204 static void ads7846_disable(struct ads7846 *ts);
205
206 static int device_suspended(struct device *dev)
207 {
208         struct ads7846 *ts = dev_get_drvdata(dev);
209         return ts->is_suspended || ts->disabled;
210 }
211
212 static int ads7846_read12_ser(struct device *dev, unsigned command)
213 {
214         struct spi_device       *spi = to_spi_device(dev);
215         struct ads7846          *ts = dev_get_drvdata(dev);
216         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
217         int                     status;
218         int                     use_internal;
219
220         if (!req)
221                 return -ENOMEM;
222
223         spi_message_init(&req->msg);
224
225         /* FIXME boards with ads7846 might use external vref instead ... */
226         use_internal = (ts->model == 7846);
227
228         /* maybe turn on internal vREF, and let it settle */
229         if (use_internal) {
230                 req->ref_on = REF_ON;
231                 req->xfer[0].tx_buf = &req->ref_on;
232                 req->xfer[0].len = 1;
233                 spi_message_add_tail(&req->xfer[0], &req->msg);
234
235                 req->xfer[1].rx_buf = &req->scratch;
236                 req->xfer[1].len = 2;
237
238                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
239                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
240                 spi_message_add_tail(&req->xfer[1], &req->msg);
241         }
242
243         /* take sample */
244         req->command = (u8) command;
245         req->xfer[2].tx_buf = &req->command;
246         req->xfer[2].len = 1;
247         spi_message_add_tail(&req->xfer[2], &req->msg);
248
249         req->xfer[3].rx_buf = &req->sample;
250         req->xfer[3].len = 2;
251         spi_message_add_tail(&req->xfer[3], &req->msg);
252
253         /* REVISIT:  take a few more samples, and compare ... */
254
255         /* converter in low power mode & enable PENIRQ */
256         req->ref_off = PWRDOWN;
257         req->xfer[4].tx_buf = &req->ref_off;
258         req->xfer[4].len = 1;
259         spi_message_add_tail(&req->xfer[4], &req->msg);
260
261         req->xfer[5].rx_buf = &req->scratch;
262         req->xfer[5].len = 2;
263         CS_CHANGE(req->xfer[5]);
264         spi_message_add_tail(&req->xfer[5], &req->msg);
265
266         ts->irq_disabled = 1;
267         disable_irq(spi->irq);
268         status = spi_sync(spi, &req->msg);
269         ts->irq_disabled = 0;
270         enable_irq(spi->irq);
271
272         if (status == 0) {
273                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
274                 status = be16_to_cpu(req->sample);
275                 status = status >> 3;
276                 status &= 0x0fff;
277         }
278
279         kfree(req);
280         return status;
281 }
282
283 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
284
285 #define SHOW(name, var, adjust) static ssize_t \
286 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
287 { \
288         struct ads7846 *ts = dev_get_drvdata(dev); \
289         ssize_t v = ads7846_read12_ser(dev, \
290                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
291         if (v < 0) \
292                 return v; \
293         return sprintf(buf, "%u\n", adjust(ts, v)); \
294 } \
295 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
296
297
298 /* Sysfs conventions report temperatures in millidegrees Celcius.
299  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
300  * accuracy scheme without calibration data.  For now we won't try either;
301  * userspace sees raw sensor values, and must scale/calibrate appropriately.
302  */
303 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
304 {
305         return v;
306 }
307
308 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
309 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
310
311
312 /* sysfs conventions report voltages in millivolts.  We can convert voltages
313  * if we know vREF.  userspace may need to scale vAUX to match the board's
314  * external resistors; we assume that vBATT only uses the internal ones.
315  */
316 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
317 {
318         unsigned retval = v;
319
320         /* external resistors may scale vAUX into 0..vREF */
321         retval *= ts->vref_mv;
322         retval = retval >> 12;
323         return retval;
324 }
325
326 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
327 {
328         unsigned retval = vaux_adjust(ts, v);
329
330         /* ads7846 has a resistor ladder to scale this signal down */
331         if (ts->model == 7846)
332                 retval *= 4;
333         return retval;
334 }
335
336 SHOW(in0_input, vaux, vaux_adjust)
337 SHOW(in1_input, vbatt, vbatt_adjust)
338
339
340 static struct attribute *ads7846_attributes[] = {
341         &dev_attr_temp0.attr,
342         &dev_attr_temp1.attr,
343         &dev_attr_in0_input.attr,
344         &dev_attr_in1_input.attr,
345         NULL,
346 };
347
348 static struct attribute_group ads7846_attr_group = {
349         .attrs = ads7846_attributes,
350 };
351
352 static struct attribute *ads7843_attributes[] = {
353         &dev_attr_in0_input.attr,
354         &dev_attr_in1_input.attr,
355         NULL,
356 };
357
358 static struct attribute_group ads7843_attr_group = {
359         .attrs = ads7843_attributes,
360 };
361
362 static struct attribute *ads7845_attributes[] = {
363         &dev_attr_in0_input.attr,
364         NULL,
365 };
366
367 static struct attribute_group ads7845_attr_group = {
368         .attrs = ads7845_attributes,
369 };
370
371 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
372 {
373         struct device *hwmon;
374         int err;
375
376         /* hwmon sensors need a reference voltage */
377         switch (ts->model) {
378         case 7846:
379                 if (!ts->vref_mv) {
380                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
381                         ts->vref_mv = 2500;
382                 }
383                 break;
384         case 7845:
385         case 7843:
386                 if (!ts->vref_mv) {
387                         dev_warn(&spi->dev,
388                                 "external vREF for ADS%d not specified\n",
389                                 ts->model);
390                         return 0;
391                 }
392                 break;
393         }
394
395         /* different chips have different sensor groups */
396         switch (ts->model) {
397         case 7846:
398                 ts->attr_group = &ads7846_attr_group;
399                 break;
400         case 7845:
401                 ts->attr_group = &ads7845_attr_group;
402                 break;
403         case 7843:
404                 ts->attr_group = &ads7843_attr_group;
405                 break;
406         default:
407                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
408                 return 0;
409         }
410
411         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
412         if (err)
413                 return err;
414
415         hwmon = hwmon_device_register(&spi->dev);
416         if (IS_ERR(hwmon)) {
417                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
418                 return PTR_ERR(hwmon);
419         }
420
421         ts->hwmon = hwmon;
422         return 0;
423 }
424
425 static void ads784x_hwmon_unregister(struct spi_device *spi,
426                                      struct ads7846 *ts)
427 {
428         if (ts->hwmon) {
429                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
430                 hwmon_device_unregister(ts->hwmon);
431         }
432 }
433
434 #else
435 static inline int ads784x_hwmon_register(struct spi_device *spi,
436                                          struct ads7846 *ts)
437 {
438         return 0;
439 }
440
441 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
442                                             struct ads7846 *ts)
443 {
444 }
445 #endif
446
447 static int is_pen_down(struct device *dev)
448 {
449         struct ads7846  *ts = dev_get_drvdata(dev);
450
451         return ts->pendown;
452 }
453
454 static ssize_t ads7846_pen_down_show(struct device *dev,
455                                      struct device_attribute *attr, char *buf)
456 {
457         return sprintf(buf, "%u\n", is_pen_down(dev));
458 }
459
460 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
461
462 static ssize_t ads7846_disable_show(struct device *dev,
463                                      struct device_attribute *attr, char *buf)
464 {
465         struct ads7846  *ts = dev_get_drvdata(dev);
466
467         return sprintf(buf, "%u\n", ts->disabled);
468 }
469
470 static ssize_t ads7846_disable_store(struct device *dev,
471                                      struct device_attribute *attr,
472                                      const char *buf, size_t count)
473 {
474         struct ads7846 *ts = dev_get_drvdata(dev);
475         unsigned long i;
476
477         if (strict_strtoul(buf, 10, &i))
478                 return -EINVAL;
479
480         spin_lock_irq(&ts->lock);
481
482         if (i)
483                 ads7846_disable(ts);
484         else
485                 ads7846_enable(ts);
486
487         spin_unlock_irq(&ts->lock);
488
489         return count;
490 }
491
492 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
493
494 static struct attribute *ads784x_attributes[] = {
495         &dev_attr_pen_down.attr,
496         &dev_attr_disable.attr,
497         NULL,
498 };
499
500 static struct attribute_group ads784x_attr_group = {
501         .attrs = ads784x_attributes,
502 };
503
504 /*--------------------------------------------------------------------------*/
505
506 static int get_pendown_state(struct ads7846 *ts)
507 {
508         if (ts->get_pendown_state)
509                 return ts->get_pendown_state();
510
511         return !gpio_get_value(ts->gpio_pendown);
512 }
513
514 /*
515  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
516  * to retrieve touchscreen status.
517  *
518  * The SPI transfer completion callback does the real work.  It reports
519  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
520  */
521
522 static void ads7846_rx(void *ads)
523 {
524         struct ads7846          *ts = ads;
525         struct ads7846_packet   *packet = ts->packet;
526         unsigned                Rt;
527         u16                     x, y, z1, z2;
528
529         /* ads7846_rx_val() did in-place conversion (including byteswap) from
530          * on-the-wire format as part of debouncing to get stable readings.
531          */
532         x = packet->tc.x;
533         y = packet->tc.y;
534         z1 = packet->tc.z1;
535         z2 = packet->tc.z2;
536
537         /* range filtering */
538         if (x == MAX_12BIT)
539                 x = 0;
540
541         if (ts->model == 7843) {
542                 Rt = ts->pressure_max / 2;
543         } else if (likely(x && z1)) {
544                 /* compute touch pressure resistance using equation #2 */
545                 Rt = z2;
546                 Rt -= z1;
547                 Rt *= x;
548                 Rt *= ts->x_plate_ohms;
549                 Rt /= z1;
550                 Rt = (Rt + 2047) >> 12;
551         } else {
552                 Rt = 0;
553         }
554
555         /* Sample found inconsistent by debouncing or pressure is beyond
556          * the maximum. Don't report it to user space, repeat at least
557          * once more the measurement
558          */
559         if (packet->tc.ignore || Rt > ts->pressure_max) {
560 #ifdef VERBOSE
561                 pr_debug("%s: ignored %d pressure %d\n",
562                         dev_name(&ts->spi->dev), packet->tc.ignore, Rt);
563 #endif
564                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
565                               HRTIMER_MODE_REL);
566                 return;
567         }
568
569         /* Maybe check the pendown state before reporting. This discards
570          * false readings when the pen is lifted.
571          */
572         if (ts->penirq_recheck_delay_usecs) {
573                 udelay(ts->penirq_recheck_delay_usecs);
574                 if (!get_pendown_state(ts))
575                         Rt = 0;
576         }
577
578         /* NOTE: We can't rely on the pressure to determine the pen down
579          * state, even this controller has a pressure sensor.  The pressure
580          * value can fluctuate for quite a while after lifting the pen and
581          * in some cases may not even settle at the expected value.
582          *
583          * The only safe way to check for the pen up condition is in the
584          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
585          */
586         if (Rt) {
587                 struct input_dev *input = ts->input;
588
589                 if (!ts->pendown) {
590                         input_report_key(input, BTN_TOUCH, 1);
591                         ts->pendown = 1;
592 #ifdef VERBOSE
593                         dev_dbg(&ts->spi->dev, "DOWN\n");
594 #endif
595                 }
596                 input_report_abs(input, ABS_X, x);
597                 input_report_abs(input, ABS_Y, y);
598                 input_report_abs(input, ABS_PRESSURE, Rt);
599
600                 input_sync(input);
601 #ifdef VERBOSE
602                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
603 #endif
604         }
605
606         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
607                         HRTIMER_MODE_REL);
608 }
609
610 static int ads7846_debounce(void *ads, int data_idx, int *val)
611 {
612         struct ads7846          *ts = ads;
613
614         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
615                 /* Start over collecting consistent readings. */
616                 ts->read_rep = 0;
617                 /* Repeat it, if this was the first read or the read
618                  * wasn't consistent enough. */
619                 if (ts->read_cnt < ts->debounce_max) {
620                         ts->last_read = *val;
621                         ts->read_cnt++;
622                         return ADS7846_FILTER_REPEAT;
623                 } else {
624                         /* Maximum number of debouncing reached and still
625                          * not enough number of consistent readings. Abort
626                          * the whole sample, repeat it in the next sampling
627                          * period.
628                          */
629                         ts->read_cnt = 0;
630                         return ADS7846_FILTER_IGNORE;
631                 }
632         } else {
633                 if (++ts->read_rep > ts->debounce_rep) {
634                         /* Got a good reading for this coordinate,
635                          * go for the next one. */
636                         ts->read_cnt = 0;
637                         ts->read_rep = 0;
638                         return ADS7846_FILTER_OK;
639                 } else {
640                         /* Read more values that are consistent. */
641                         ts->read_cnt++;
642                         return ADS7846_FILTER_REPEAT;
643                 }
644         }
645 }
646
647 static int ads7846_no_filter(void *ads, int data_idx, int *val)
648 {
649         return ADS7846_FILTER_OK;
650 }
651
652 static void ads7846_rx_val(void *ads)
653 {
654         struct ads7846 *ts = ads;
655         struct ads7846_packet *packet = ts->packet;
656         struct spi_message *m;
657         struct spi_transfer *t;
658         int val;
659         int action;
660         int status;
661
662         m = &ts->msg[ts->msg_idx];
663         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
664
665         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
666          * built from two 8 bit values written msb-first.
667          */
668         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
669
670         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
671         switch (action) {
672         case ADS7846_FILTER_REPEAT:
673                 break;
674         case ADS7846_FILTER_IGNORE:
675                 packet->tc.ignore = 1;
676                 /* Last message will contain ads7846_rx() as the
677                  * completion function.
678                  */
679                 m = ts->last_msg;
680                 break;
681         case ADS7846_FILTER_OK:
682                 *(u16 *)t->rx_buf = val;
683                 packet->tc.ignore = 0;
684                 m = &ts->msg[++ts->msg_idx];
685                 break;
686         default:
687                 BUG();
688         }
689         status = spi_async(ts->spi, m);
690         if (status)
691                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
692                                 status);
693 }
694
695 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
696 {
697         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
698         int             status = 0;
699
700         spin_lock(&ts->lock);
701
702         if (unlikely(!get_pendown_state(ts) ||
703                      device_suspended(&ts->spi->dev))) {
704                 if (ts->pendown) {
705                         struct input_dev *input = ts->input;
706
707                         input_report_key(input, BTN_TOUCH, 0);
708                         input_report_abs(input, ABS_PRESSURE, 0);
709                         input_sync(input);
710
711                         ts->pendown = 0;
712 #ifdef VERBOSE
713                         dev_dbg(&ts->spi->dev, "UP\n");
714 #endif
715                 }
716
717                 /* measurement cycle ended */
718                 if (!device_suspended(&ts->spi->dev)) {
719                         ts->irq_disabled = 0;
720                         enable_irq(ts->spi->irq);
721                 }
722                 ts->pending = 0;
723         } else {
724                 /* pen is still down, continue with the measurement */
725                 ts->msg_idx = 0;
726                 status = spi_async(ts->spi, &ts->msg[0]);
727                 if (status)
728                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
729         }
730
731         spin_unlock(&ts->lock);
732         return HRTIMER_NORESTART;
733 }
734
735 static irqreturn_t ads7846_irq(int irq, void *handle)
736 {
737         struct ads7846 *ts = handle;
738         unsigned long flags;
739
740         spin_lock_irqsave(&ts->lock, flags);
741         if (likely(get_pendown_state(ts))) {
742                 if (!ts->irq_disabled) {
743                         /* The ARM do_simple_IRQ() dispatcher doesn't act
744                          * like the other dispatchers:  it will report IRQs
745                          * even after they've been disabled.  We work around
746                          * that here.  (The "generic irq" framework may help...)
747                          */
748                         ts->irq_disabled = 1;
749                         disable_irq(ts->spi->irq);
750                         ts->pending = 1;
751                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
752                                         HRTIMER_MODE_REL);
753                 }
754         }
755         spin_unlock_irqrestore(&ts->lock, flags);
756
757         return IRQ_HANDLED;
758 }
759
760 /*--------------------------------------------------------------------------*/
761
762 /* Must be called with ts->lock held */
763 static void ads7846_disable(struct ads7846 *ts)
764 {
765         if (ts->disabled)
766                 return;
767
768         ts->disabled = 1;
769
770         /* are we waiting for IRQ, or polling? */
771         if (!ts->pending) {
772                 ts->irq_disabled = 1;
773                 disable_irq(ts->spi->irq);
774         } else {
775                 /* the timer will run at least once more, and
776                  * leave everything in a clean state, IRQ disabled
777                  */
778                 while (ts->pending) {
779                         spin_unlock_irq(&ts->lock);
780                         msleep(1);
781                         spin_lock_irq(&ts->lock);
782                 }
783         }
784
785         /* we know the chip's in lowpower mode since we always
786          * leave it that way after every request
787          */
788 }
789
790 /* Must be called with ts->lock held */
791 static void ads7846_enable(struct ads7846 *ts)
792 {
793         if (!ts->disabled)
794                 return;
795
796         ts->disabled = 0;
797         ts->irq_disabled = 0;
798         enable_irq(ts->spi->irq);
799 }
800
801 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
802 {
803         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
804
805         spin_lock_irq(&ts->lock);
806
807         ts->is_suspended = 1;
808         ads7846_disable(ts);
809
810         spin_unlock_irq(&ts->lock);
811
812         return 0;
813
814 }
815
816 static int ads7846_resume(struct spi_device *spi)
817 {
818         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
819
820         spin_lock_irq(&ts->lock);
821
822         ts->is_suspended = 0;
823         ads7846_enable(ts);
824
825         spin_unlock_irq(&ts->lock);
826
827         return 0;
828 }
829
830 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
831 {
832         struct ads7846_platform_data *pdata = spi->dev.platform_data;
833         int err;
834
835         /* REVISIT when the irq can be triggered active-low, or if for some
836          * reason the touchscreen isn't hooked up, we don't need to access
837          * the pendown state.
838          */
839         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
840                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
841                 return -EINVAL;
842         }
843
844         if (pdata->get_pendown_state) {
845                 ts->get_pendown_state = pdata->get_pendown_state;
846                 return 0;
847         }
848
849         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
850         if (err) {
851                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
852                                 pdata->gpio_pendown);
853                 return err;
854         }
855
856         ts->gpio_pendown = pdata->gpio_pendown;
857         return 0;
858 }
859
860 static int __devinit ads7846_probe(struct spi_device *spi)
861 {
862         struct ads7846                  *ts;
863         struct ads7846_packet           *packet;
864         struct input_dev                *input_dev;
865         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
866         struct spi_message              *m;
867         struct spi_transfer             *x;
868         int                             vref;
869         int                             err;
870
871         if (!spi->irq) {
872                 dev_dbg(&spi->dev, "no IRQ?\n");
873                 return -ENODEV;
874         }
875
876         if (!pdata) {
877                 dev_dbg(&spi->dev, "no platform data?\n");
878                 return -ENODEV;
879         }
880
881         /* don't exceed max specified sample rate */
882         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
883                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
884                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
885                 return -EINVAL;
886         }
887
888         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
889          * that even if the hardware can do that, the SPI controller driver
890          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
891          */
892         spi->bits_per_word = 8;
893         spi->mode = SPI_MODE_0;
894         err = spi_setup(spi);
895         if (err < 0)
896                 return err;
897
898         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
899         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
900         input_dev = input_allocate_device();
901         if (!ts || !packet || !input_dev) {
902                 err = -ENOMEM;
903                 goto err_free_mem;
904         }
905
906         dev_set_drvdata(&spi->dev, ts);
907
908         ts->packet = packet;
909         ts->spi = spi;
910         ts->input = input_dev;
911         ts->vref_mv = pdata->vref_mv;
912
913         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
914         ts->timer.function = ads7846_timer;
915
916         spin_lock_init(&ts->lock);
917
918         ts->model = pdata->model ? : 7846;
919         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
920         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
921         ts->pressure_max = pdata->pressure_max ? : ~0;
922
923         if (pdata->filter != NULL) {
924                 if (pdata->filter_init != NULL) {
925                         err = pdata->filter_init(pdata, &ts->filter_data);
926                         if (err < 0)
927                                 goto err_free_mem;
928                 }
929                 ts->filter = pdata->filter;
930                 ts->filter_cleanup = pdata->filter_cleanup;
931         } else if (pdata->debounce_max) {
932                 ts->debounce_max = pdata->debounce_max;
933                 if (ts->debounce_max < 2)
934                         ts->debounce_max = 2;
935                 ts->debounce_tol = pdata->debounce_tol;
936                 ts->debounce_rep = pdata->debounce_rep;
937                 ts->filter = ads7846_debounce;
938                 ts->filter_data = ts;
939         } else
940                 ts->filter = ads7846_no_filter;
941
942         err = setup_pendown(spi, ts);
943         if (err)
944                 goto err_cleanup_filter;
945
946         if (pdata->penirq_recheck_delay_usecs)
947                 ts->penirq_recheck_delay_usecs =
948                                 pdata->penirq_recheck_delay_usecs;
949
950         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
951
952         input_dev->name = "ADS784x Touchscreen";
953         input_dev->phys = ts->phys;
954         input_dev->dev.parent = &spi->dev;
955
956         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
957         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
958         input_set_abs_params(input_dev, ABS_X,
959                         pdata->x_min ? : 0,
960                         pdata->x_max ? : MAX_12BIT,
961                         0, 0);
962         input_set_abs_params(input_dev, ABS_Y,
963                         pdata->y_min ? : 0,
964                         pdata->y_max ? : MAX_12BIT,
965                         0, 0);
966         input_set_abs_params(input_dev, ABS_PRESSURE,
967                         pdata->pressure_min, pdata->pressure_max, 0, 0);
968
969         vref = pdata->keep_vref_on;
970
971         /* set up the transfers to read touchscreen state; this assumes we
972          * use formula #2 for pressure, not #3.
973          */
974         m = &ts->msg[0];
975         x = ts->xfer;
976
977         spi_message_init(m);
978
979         /* y- still on; turn on only y+ (and ADC) */
980         packet->read_y = READ_Y(vref);
981         x->tx_buf = &packet->read_y;
982         x->len = 1;
983         spi_message_add_tail(x, m);
984
985         x++;
986         x->rx_buf = &packet->tc.y;
987         x->len = 2;
988         spi_message_add_tail(x, m);
989
990         /* the first sample after switching drivers can be low quality;
991          * optionally discard it, using a second one after the signals
992          * have had enough time to stabilize.
993          */
994         if (pdata->settle_delay_usecs) {
995                 x->delay_usecs = pdata->settle_delay_usecs;
996
997                 x++;
998                 x->tx_buf = &packet->read_y;
999                 x->len = 1;
1000                 spi_message_add_tail(x, m);
1001
1002                 x++;
1003                 x->rx_buf = &packet->tc.y;
1004                 x->len = 2;
1005                 spi_message_add_tail(x, m);
1006         }
1007
1008         m->complete = ads7846_rx_val;
1009         m->context = ts;
1010
1011         m++;
1012         spi_message_init(m);
1013
1014         /* turn y- off, x+ on, then leave in lowpower */
1015         x++;
1016         packet->read_x = READ_X(vref);
1017         x->tx_buf = &packet->read_x;
1018         x->len = 1;
1019         spi_message_add_tail(x, m);
1020
1021         x++;
1022         x->rx_buf = &packet->tc.x;
1023         x->len = 2;
1024         spi_message_add_tail(x, m);
1025
1026         /* ... maybe discard first sample ... */
1027         if (pdata->settle_delay_usecs) {
1028                 x->delay_usecs = pdata->settle_delay_usecs;
1029
1030                 x++;
1031                 x->tx_buf = &packet->read_x;
1032                 x->len = 1;
1033                 spi_message_add_tail(x, m);
1034
1035                 x++;
1036                 x->rx_buf = &packet->tc.x;
1037                 x->len = 2;
1038                 spi_message_add_tail(x, m);
1039         }
1040
1041         m->complete = ads7846_rx_val;
1042         m->context = ts;
1043
1044         /* turn y+ off, x- on; we'll use formula #2 */
1045         if (ts->model == 7846) {
1046                 m++;
1047                 spi_message_init(m);
1048
1049                 x++;
1050                 packet->read_z1 = READ_Z1(vref);
1051                 x->tx_buf = &packet->read_z1;
1052                 x->len = 1;
1053                 spi_message_add_tail(x, m);
1054
1055                 x++;
1056                 x->rx_buf = &packet->tc.z1;
1057                 x->len = 2;
1058                 spi_message_add_tail(x, m);
1059
1060                 /* ... maybe discard first sample ... */
1061                 if (pdata->settle_delay_usecs) {
1062                         x->delay_usecs = pdata->settle_delay_usecs;
1063
1064                         x++;
1065                         x->tx_buf = &packet->read_z1;
1066                         x->len = 1;
1067                         spi_message_add_tail(x, m);
1068
1069                         x++;
1070                         x->rx_buf = &packet->tc.z1;
1071                         x->len = 2;
1072                         spi_message_add_tail(x, m);
1073                 }
1074
1075                 m->complete = ads7846_rx_val;
1076                 m->context = ts;
1077
1078                 m++;
1079                 spi_message_init(m);
1080
1081                 x++;
1082                 packet->read_z2 = READ_Z2(vref);
1083                 x->tx_buf = &packet->read_z2;
1084                 x->len = 1;
1085                 spi_message_add_tail(x, m);
1086
1087                 x++;
1088                 x->rx_buf = &packet->tc.z2;
1089                 x->len = 2;
1090                 spi_message_add_tail(x, m);
1091
1092                 /* ... maybe discard first sample ... */
1093                 if (pdata->settle_delay_usecs) {
1094                         x->delay_usecs = pdata->settle_delay_usecs;
1095
1096                         x++;
1097                         x->tx_buf = &packet->read_z2;
1098                         x->len = 1;
1099                         spi_message_add_tail(x, m);
1100
1101                         x++;
1102                         x->rx_buf = &packet->tc.z2;
1103                         x->len = 2;
1104                         spi_message_add_tail(x, m);
1105                 }
1106
1107                 m->complete = ads7846_rx_val;
1108                 m->context = ts;
1109         }
1110
1111         /* power down */
1112         m++;
1113         spi_message_init(m);
1114
1115         x++;
1116         packet->pwrdown = PWRDOWN;
1117         x->tx_buf = &packet->pwrdown;
1118         x->len = 1;
1119         spi_message_add_tail(x, m);
1120
1121         x++;
1122         x->rx_buf = &packet->dummy;
1123         x->len = 2;
1124         CS_CHANGE(*x);
1125         spi_message_add_tail(x, m);
1126
1127         m->complete = ads7846_rx;
1128         m->context = ts;
1129
1130         ts->last_msg = m;
1131
1132         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1133                         spi->dev.driver->name, ts)) {
1134                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1135                 err = -EBUSY;
1136                 goto err_free_gpio;
1137         }
1138
1139         err = ads784x_hwmon_register(spi, ts);
1140         if (err)
1141                 goto err_free_irq;
1142
1143         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1144
1145         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1146          * the touchscreen, in case it's not connected.
1147          */
1148         (void) ads7846_read12_ser(&spi->dev,
1149                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1150
1151         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1152         if (err)
1153                 goto err_remove_hwmon;
1154
1155         err = input_register_device(input_dev);
1156         if (err)
1157                 goto err_remove_attr_group;
1158
1159         return 0;
1160
1161  err_remove_attr_group:
1162         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1163  err_remove_hwmon:
1164         ads784x_hwmon_unregister(spi, ts);
1165  err_free_irq:
1166         free_irq(spi->irq, ts);
1167  err_free_gpio:
1168         if (ts->gpio_pendown != -1)
1169                 gpio_free(ts->gpio_pendown);
1170  err_cleanup_filter:
1171         if (ts->filter_cleanup)
1172                 ts->filter_cleanup(ts->filter_data);
1173  err_free_mem:
1174         input_free_device(input_dev);
1175         kfree(packet);
1176         kfree(ts);
1177         return err;
1178 }
1179
1180 static int __devexit ads7846_remove(struct spi_device *spi)
1181 {
1182         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1183
1184         ads784x_hwmon_unregister(spi, ts);
1185         input_unregister_device(ts->input);
1186
1187         ads7846_suspend(spi, PMSG_SUSPEND);
1188
1189         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1190
1191         free_irq(ts->spi->irq, ts);
1192         /* suspend left the IRQ disabled */
1193         enable_irq(ts->spi->irq);
1194
1195         if (ts->gpio_pendown != -1)
1196                 gpio_free(ts->gpio_pendown);
1197
1198         if (ts->filter_cleanup)
1199                 ts->filter_cleanup(ts->filter_data);
1200
1201         kfree(ts->packet);
1202         kfree(ts);
1203
1204         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1205         return 0;
1206 }
1207
1208 static struct spi_driver ads7846_driver = {
1209         .driver = {
1210                 .name   = "ads7846",
1211                 .bus    = &spi_bus_type,
1212                 .owner  = THIS_MODULE,
1213         },
1214         .probe          = ads7846_probe,
1215         .remove         = __devexit_p(ads7846_remove),
1216         .suspend        = ads7846_suspend,
1217         .resume         = ads7846_resume,
1218 };
1219
1220 static int __init ads7846_init(void)
1221 {
1222         return spi_register_driver(&ads7846_driver);
1223 }
1224 module_init(ads7846_init);
1225
1226 static void __exit ads7846_exit(void)
1227 {
1228         spi_unregister_driver(&ads7846_driver);
1229 }
1230 module_exit(ads7846_exit);
1231
1232 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1233 MODULE_LICENSE("GPL");