Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi...
[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/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 <asm/irq.h>
35
36 /*
37  * This code has been heavily tested on a Nokia 770, and lightly
38  * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
39  * TSC2046 is just newer ads7846 silicon.
40  * Support for ads7843 tested on Atmel at91sam926x-EK.
41  * Support for ads7845 has only been stubbed in.
42  * Support for Analog Devices AD7873 and AD7843 tested.
43  *
44  * IRQ handling needs a workaround because of a shortcoming in handling
45  * edge triggered IRQs on some platforms like the OMAP1/2. These
46  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
47  * have to maintain our own SW IRQ disabled status. This should be
48  * removed as soon as the affected platform's IRQ handling is fixed.
49  *
50  * App note sbaa036 talks in more detail about accurate sampling...
51  * that ought to help in situations like LCDs inducing noise (which
52  * can also be helped by using synch signals) and more generally.
53  * This driver tries to utilize the measures described in the app
54  * note. The strength of filtering can be set in the board-* specific
55  * files.
56  */
57
58 #define TS_POLL_DELAY   1       /* ms delay before the first sample */
59 #define TS_POLL_PERIOD  5       /* ms delay between samples */
60
61 /* this driver doesn't aim at the peak continuous sample rate */
62 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
63
64 struct ts_event {
65         /*
66          * For portability, we can't read 12 bit values using SPI (which
67          * would make the controller deliver them as native byte order u16
68          * with msbs zeroed).  Instead, we read them as two 8-bit values,
69          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
70          */
71         u16     x;
72         u16     y;
73         u16     z1, z2;
74         bool    ignore;
75         u8      x_buf[3];
76         u8      y_buf[3];
77 };
78
79 /*
80  * We allocate this separately to avoid cache line sharing issues when
81  * driver is used with DMA-based SPI controllers (like atmel_spi) on
82  * systems where main memory is not DMA-coherent (most non-x86 boards).
83  */
84 struct ads7846_packet {
85         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
86         u16                     dummy;          /* for the pwrdown read */
87         struct ts_event         tc;
88         /* for ads7845 with mpc5121 psc spi we use 3-byte buffers */
89         u8                      read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3];
90 };
91
92 struct ads7846 {
93         struct input_dev        *input;
94         char                    phys[32];
95         char                    name[32];
96
97         struct spi_device       *spi;
98         struct regulator        *reg;
99
100 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
101         struct attribute_group  *attr_group;
102         struct device           *hwmon;
103 #endif
104
105         u16                     model;
106         u16                     vref_mv;
107         u16                     vref_delay_usecs;
108         u16                     x_plate_ohms;
109         u16                     pressure_max;
110
111         bool                    swap_xy;
112
113         struct ads7846_packet   *packet;
114
115         struct spi_transfer     xfer[18];
116         struct spi_message      msg[5];
117         int                     msg_count;
118         wait_queue_head_t       wait;
119
120         bool                    pendown;
121
122         int                     read_cnt;
123         int                     read_rep;
124         int                     last_read;
125
126         u16                     debounce_max;
127         u16                     debounce_tol;
128         u16                     debounce_rep;
129
130         u16                     penirq_recheck_delay_usecs;
131
132         struct 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         void                    (*filter_cleanup)(void *data);
140         int                     (*get_pendown_state)(void);
141         int                     gpio_pendown;
142
143         void                    (*wait_for_sync)(void);
144 };
145
146 /* leave chip selected when we're done, for quicker re-select? */
147 #if     0
148 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
149 #else
150 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
151 #endif
152
153 /*--------------------------------------------------------------------------*/
154
155 /* The ADS7846 has touchscreen and other sensors.
156  * Earlier ads784x chips are somewhat compatible.
157  */
158 #define ADS_START               (1 << 7)
159 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
160 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
161 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
162 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
163 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
164 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
165 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
166 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
167 #define ADS_8_BIT               (1 << 3)
168 #define ADS_12_BIT              (0 << 3)
169 #define ADS_SER                 (1 << 2)        /* non-differential */
170 #define ADS_DFR                 (0 << 2)        /* differential */
171 #define ADS_PD10_PDOWN          (0 << 0)        /* low power mode + penirq */
172 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
173 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
174 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
175
176 #define MAX_12BIT       ((1<<12)-1)
177
178 /* leave ADC powered up (disables penirq) between differential samples */
179 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
180         | ADS_12_BIT | ADS_DFR | \
181         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
182
183 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
184 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
185 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
186
187 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
188 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
189
190 /* single-ended samples need to first power up reference voltage;
191  * we leave both ADC and VREF powered
192  */
193 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
194         | ADS_12_BIT | ADS_SER)
195
196 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
197 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
198
199 /* Must be called with ts->lock held */
200 static void ads7846_stop(struct ads7846 *ts)
201 {
202         if (!ts->disabled && !ts->suspended) {
203                 /* Signal IRQ thread to stop polling and disable the handler. */
204                 ts->stopped = true;
205                 mb();
206                 wake_up(&ts->wait);
207                 disable_irq(ts->spi->irq);
208         }
209 }
210
211 /* Must be called with ts->lock held */
212 static void ads7846_restart(struct ads7846 *ts)
213 {
214         if (!ts->disabled && !ts->suspended) {
215                 /* Tell IRQ thread that it may poll the device. */
216                 ts->stopped = false;
217                 mb();
218                 enable_irq(ts->spi->irq);
219         }
220 }
221
222 /* Must be called with ts->lock held */
223 static void __ads7846_disable(struct ads7846 *ts)
224 {
225         ads7846_stop(ts);
226         regulator_disable(ts->reg);
227
228         /*
229          * We know the chip's in low power mode since we always
230          * leave it that way after every request
231          */
232 }
233
234 /* Must be called with ts->lock held */
235 static void __ads7846_enable(struct ads7846 *ts)
236 {
237         regulator_enable(ts->reg);
238         ads7846_restart(ts);
239 }
240
241 static void ads7846_disable(struct ads7846 *ts)
242 {
243         mutex_lock(&ts->lock);
244
245         if (!ts->disabled) {
246
247                 if  (!ts->suspended)
248                         __ads7846_disable(ts);
249
250                 ts->disabled = true;
251         }
252
253         mutex_unlock(&ts->lock);
254 }
255
256 static void ads7846_enable(struct ads7846 *ts)
257 {
258         mutex_lock(&ts->lock);
259
260         if (ts->disabled) {
261
262                 ts->disabled = false;
263
264                 if (!ts->suspended)
265                         __ads7846_enable(ts);
266         }
267
268         mutex_unlock(&ts->lock);
269 }
270
271 /*--------------------------------------------------------------------------*/
272
273 /*
274  * Non-touchscreen sensors only use single-ended conversions.
275  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
276  * ads7846 lets that pin be unconnected, to use internal vREF.
277  */
278
279 struct ser_req {
280         u8                      ref_on;
281         u8                      command;
282         u8                      ref_off;
283         u16                     scratch;
284         __be16                  sample;
285         struct spi_message      msg;
286         struct spi_transfer     xfer[6];
287 };
288
289 struct ads7845_ser_req {
290         u8                      command[3];
291         u8                      pwrdown[3];
292         u8                      sample[3];
293         struct spi_message      msg;
294         struct spi_transfer     xfer[2];
295 };
296
297 static int ads7846_read12_ser(struct device *dev, unsigned command)
298 {
299         struct spi_device *spi = to_spi_device(dev);
300         struct ads7846 *ts = dev_get_drvdata(dev);
301         struct ser_req *req;
302         int status;
303         int use_internal;
304
305         req = kzalloc(sizeof *req, GFP_KERNEL);
306         if (!req)
307                 return -ENOMEM;
308
309         spi_message_init(&req->msg);
310
311         /* FIXME boards with ads7846 might use external vref instead ... */
312         use_internal = (ts->model == 7846);
313
314         /* maybe turn on internal vREF, and let it settle */
315         if (use_internal) {
316                 req->ref_on = REF_ON;
317                 req->xfer[0].tx_buf = &req->ref_on;
318                 req->xfer[0].len = 1;
319                 spi_message_add_tail(&req->xfer[0], &req->msg);
320
321                 req->xfer[1].rx_buf = &req->scratch;
322                 req->xfer[1].len = 2;
323
324                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
325                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
326                 spi_message_add_tail(&req->xfer[1], &req->msg);
327         }
328
329         /* take sample */
330         req->command = (u8) command;
331         req->xfer[2].tx_buf = &req->command;
332         req->xfer[2].len = 1;
333         spi_message_add_tail(&req->xfer[2], &req->msg);
334
335         req->xfer[3].rx_buf = &req->sample;
336         req->xfer[3].len = 2;
337         spi_message_add_tail(&req->xfer[3], &req->msg);
338
339         /* REVISIT:  take a few more samples, and compare ... */
340
341         /* converter in low power mode & enable PENIRQ */
342         req->ref_off = PWRDOWN;
343         req->xfer[4].tx_buf = &req->ref_off;
344         req->xfer[4].len = 1;
345         spi_message_add_tail(&req->xfer[4], &req->msg);
346
347         req->xfer[5].rx_buf = &req->scratch;
348         req->xfer[5].len = 2;
349         CS_CHANGE(req->xfer[5]);
350         spi_message_add_tail(&req->xfer[5], &req->msg);
351
352         mutex_lock(&ts->lock);
353         ads7846_stop(ts);
354         status = spi_sync(spi, &req->msg);
355         ads7846_restart(ts);
356         mutex_unlock(&ts->lock);
357
358         if (status == 0) {
359                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
360                 status = be16_to_cpu(req->sample);
361                 status = status >> 3;
362                 status &= 0x0fff;
363         }
364
365         kfree(req);
366         return status;
367 }
368
369 static int ads7845_read12_ser(struct device *dev, unsigned command)
370 {
371         struct spi_device *spi = to_spi_device(dev);
372         struct ads7846 *ts = dev_get_drvdata(dev);
373         struct ads7845_ser_req *req;
374         int status;
375
376         req = kzalloc(sizeof *req, GFP_KERNEL);
377         if (!req)
378                 return -ENOMEM;
379
380         spi_message_init(&req->msg);
381
382         req->command[0] = (u8) command;
383         req->xfer[0].tx_buf = req->command;
384         req->xfer[0].rx_buf = req->sample;
385         req->xfer[0].len = 3;
386         spi_message_add_tail(&req->xfer[0], &req->msg);
387
388         mutex_lock(&ts->lock);
389         ads7846_stop(ts);
390         status = spi_sync(spi, &req->msg);
391         ads7846_restart(ts);
392         mutex_unlock(&ts->lock);
393
394         if (status == 0) {
395                 /* BE12 value, then padding */
396                 status = be16_to_cpu(*((u16 *)&req->sample[1]));
397                 status = status >> 3;
398                 status &= 0x0fff;
399         }
400
401         kfree(req);
402         return status;
403 }
404
405 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
406
407 #define SHOW(name, var, adjust) static ssize_t \
408 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
409 { \
410         struct ads7846 *ts = dev_get_drvdata(dev); \
411         ssize_t v = ads7846_read12_ser(dev, \
412                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
413         if (v < 0) \
414                 return v; \
415         return sprintf(buf, "%u\n", adjust(ts, v)); \
416 } \
417 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
418
419
420 /* Sysfs conventions report temperatures in millidegrees Celsius.
421  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
422  * accuracy scheme without calibration data.  For now we won't try either;
423  * userspace sees raw sensor values, and must scale/calibrate appropriately.
424  */
425 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
426 {
427         return v;
428 }
429
430 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
431 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
432
433
434 /* sysfs conventions report voltages in millivolts.  We can convert voltages
435  * if we know vREF.  userspace may need to scale vAUX to match the board's
436  * external resistors; we assume that vBATT only uses the internal ones.
437  */
438 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
439 {
440         unsigned retval = v;
441
442         /* external resistors may scale vAUX into 0..vREF */
443         retval *= ts->vref_mv;
444         retval = retval >> 12;
445
446         return retval;
447 }
448
449 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
450 {
451         unsigned retval = vaux_adjust(ts, v);
452
453         /* ads7846 has a resistor ladder to scale this signal down */
454         if (ts->model == 7846)
455                 retval *= 4;
456
457         return retval;
458 }
459
460 SHOW(in0_input, vaux, vaux_adjust)
461 SHOW(in1_input, vbatt, vbatt_adjust)
462
463 static struct attribute *ads7846_attributes[] = {
464         &dev_attr_temp0.attr,
465         &dev_attr_temp1.attr,
466         &dev_attr_in0_input.attr,
467         &dev_attr_in1_input.attr,
468         NULL,
469 };
470
471 static struct attribute_group ads7846_attr_group = {
472         .attrs = ads7846_attributes,
473 };
474
475 static struct attribute *ads7843_attributes[] = {
476         &dev_attr_in0_input.attr,
477         &dev_attr_in1_input.attr,
478         NULL,
479 };
480
481 static struct attribute_group ads7843_attr_group = {
482         .attrs = ads7843_attributes,
483 };
484
485 static struct attribute *ads7845_attributes[] = {
486         &dev_attr_in0_input.attr,
487         NULL,
488 };
489
490 static struct attribute_group ads7845_attr_group = {
491         .attrs = ads7845_attributes,
492 };
493
494 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
495 {
496         struct device *hwmon;
497         int err;
498
499         /* hwmon sensors need a reference voltage */
500         switch (ts->model) {
501         case 7846:
502                 if (!ts->vref_mv) {
503                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
504                         ts->vref_mv = 2500;
505                 }
506                 break;
507         case 7845:
508         case 7843:
509                 if (!ts->vref_mv) {
510                         dev_warn(&spi->dev,
511                                 "external vREF for ADS%d not specified\n",
512                                 ts->model);
513                         return 0;
514                 }
515                 break;
516         }
517
518         /* different chips have different sensor groups */
519         switch (ts->model) {
520         case 7846:
521                 ts->attr_group = &ads7846_attr_group;
522                 break;
523         case 7845:
524                 ts->attr_group = &ads7845_attr_group;
525                 break;
526         case 7843:
527                 ts->attr_group = &ads7843_attr_group;
528                 break;
529         default:
530                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
531                 return 0;
532         }
533
534         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
535         if (err)
536                 return err;
537
538         hwmon = hwmon_device_register(&spi->dev);
539         if (IS_ERR(hwmon)) {
540                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
541                 return PTR_ERR(hwmon);
542         }
543
544         ts->hwmon = hwmon;
545         return 0;
546 }
547
548 static void ads784x_hwmon_unregister(struct spi_device *spi,
549                                      struct ads7846 *ts)
550 {
551         if (ts->hwmon) {
552                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
553                 hwmon_device_unregister(ts->hwmon);
554         }
555 }
556
557 #else
558 static inline int ads784x_hwmon_register(struct spi_device *spi,
559                                          struct ads7846 *ts)
560 {
561         return 0;
562 }
563
564 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
565                                             struct ads7846 *ts)
566 {
567 }
568 #endif
569
570 static ssize_t ads7846_pen_down_show(struct device *dev,
571                                      struct device_attribute *attr, char *buf)
572 {
573         struct ads7846 *ts = dev_get_drvdata(dev);
574
575         return sprintf(buf, "%u\n", ts->pendown);
576 }
577
578 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
579
580 static ssize_t ads7846_disable_show(struct device *dev,
581                                      struct device_attribute *attr, char *buf)
582 {
583         struct ads7846 *ts = dev_get_drvdata(dev);
584
585         return sprintf(buf, "%u\n", ts->disabled);
586 }
587
588 static ssize_t ads7846_disable_store(struct device *dev,
589                                      struct device_attribute *attr,
590                                      const char *buf, size_t count)
591 {
592         struct ads7846 *ts = dev_get_drvdata(dev);
593         unsigned long i;
594
595         if (strict_strtoul(buf, 10, &i))
596                 return -EINVAL;
597
598         if (i)
599                 ads7846_disable(ts);
600         else
601                 ads7846_enable(ts);
602
603         return count;
604 }
605
606 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
607
608 static struct attribute *ads784x_attributes[] = {
609         &dev_attr_pen_down.attr,
610         &dev_attr_disable.attr,
611         NULL,
612 };
613
614 static struct attribute_group ads784x_attr_group = {
615         .attrs = ads784x_attributes,
616 };
617
618 /*--------------------------------------------------------------------------*/
619
620 static int get_pendown_state(struct ads7846 *ts)
621 {
622         if (ts->get_pendown_state)
623                 return ts->get_pendown_state();
624
625         return !gpio_get_value(ts->gpio_pendown);
626 }
627
628 static void null_wait_for_sync(void)
629 {
630 }
631
632 static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
633 {
634         struct ads7846 *ts = ads;
635
636         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
637                 /* Start over collecting consistent readings. */
638                 ts->read_rep = 0;
639                 /*
640                  * Repeat it, if this was the first read or the read
641                  * wasn't consistent enough.
642                  */
643                 if (ts->read_cnt < ts->debounce_max) {
644                         ts->last_read = *val;
645                         ts->read_cnt++;
646                         return ADS7846_FILTER_REPEAT;
647                 } else {
648                         /*
649                          * Maximum number of debouncing reached and still
650                          * not enough number of consistent readings. Abort
651                          * the whole sample, repeat it in the next sampling
652                          * period.
653                          */
654                         ts->read_cnt = 0;
655                         return ADS7846_FILTER_IGNORE;
656                 }
657         } else {
658                 if (++ts->read_rep > ts->debounce_rep) {
659                         /*
660                          * Got a good reading for this coordinate,
661                          * go for the next one.
662                          */
663                         ts->read_cnt = 0;
664                         ts->read_rep = 0;
665                         return ADS7846_FILTER_OK;
666                 } else {
667                         /* Read more values that are consistent. */
668                         ts->read_cnt++;
669                         return ADS7846_FILTER_REPEAT;
670                 }
671         }
672 }
673
674 static int ads7846_no_filter(void *ads, int data_idx, int *val)
675 {
676         return ADS7846_FILTER_OK;
677 }
678
679 static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m)
680 {
681         struct spi_transfer *t =
682                 list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
683
684         if (ts->model == 7845) {
685                 return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3;
686         } else {
687                 /*
688                  * adjust:  on-wire is a must-ignore bit, a BE12 value, then
689                  * padding; built from two 8 bit values written msb-first.
690                  */
691                 return be16_to_cpup((__be16 *)t->rx_buf) >> 3;
692         }
693 }
694
695 static void ads7846_update_value(struct spi_message *m, int val)
696 {
697         struct spi_transfer *t =
698                 list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
699
700         *(u16 *)t->rx_buf = val;
701 }
702
703 static void ads7846_read_state(struct ads7846 *ts)
704 {
705         struct ads7846_packet *packet = ts->packet;
706         struct spi_message *m;
707         int msg_idx = 0;
708         int val;
709         int action;
710         int error;
711
712         while (msg_idx < ts->msg_count) {
713
714                 ts->wait_for_sync();
715
716                 m = &ts->msg[msg_idx];
717                 error = spi_sync(ts->spi, m);
718                 if (error) {
719                         dev_err(&ts->spi->dev, "spi_async --> %d\n", error);
720                         packet->tc.ignore = true;
721                         return;
722                 }
723
724                 /*
725                  * Last message is power down request, no need to convert
726                  * or filter the value.
727                  */
728                 if (msg_idx < ts->msg_count - 1) {
729
730                         val = ads7846_get_value(ts, m);
731
732                         action = ts->filter(ts->filter_data, msg_idx, &val);
733                         switch (action) {
734                         case ADS7846_FILTER_REPEAT:
735                                 continue;
736
737                         case ADS7846_FILTER_IGNORE:
738                                 packet->tc.ignore = true;
739                                 msg_idx = ts->msg_count - 1;
740                                 continue;
741
742                         case ADS7846_FILTER_OK:
743                                 ads7846_update_value(m, val);
744                                 packet->tc.ignore = false;
745                                 msg_idx++;
746                                 break;
747
748                         default:
749                                 BUG();
750                         }
751                 } else {
752                         msg_idx++;
753                 }
754         }
755 }
756
757 static void ads7846_report_state(struct ads7846 *ts)
758 {
759         struct ads7846_packet *packet = ts->packet;
760         unsigned int Rt;
761         u16 x, y, z1, z2;
762
763         /*
764          * ads7846_get_value() does in-place conversion (including byte swap)
765          * from on-the-wire format as part of debouncing to get stable
766          * readings.
767          */
768         if (ts->model == 7845) {
769                 x = *(u16 *)packet->tc.x_buf;
770                 y = *(u16 *)packet->tc.y_buf;
771                 z1 = 0;
772                 z2 = 0;
773         } else {
774                 x = packet->tc.x;
775                 y = packet->tc.y;
776                 z1 = packet->tc.z1;
777                 z2 = packet->tc.z2;
778         }
779
780         /* range filtering */
781         if (x == MAX_12BIT)
782                 x = 0;
783
784         if (ts->model == 7843) {
785                 Rt = ts->pressure_max / 2;
786         } else if (ts->model == 7845) {
787                 if (get_pendown_state(ts))
788                         Rt = ts->pressure_max / 2;
789                 else
790                         Rt = 0;
791                 dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt);
792         } else if (likely(x && z1)) {
793                 /* compute touch pressure resistance using equation #2 */
794                 Rt = z2;
795                 Rt -= z1;
796                 Rt *= x;
797                 Rt *= ts->x_plate_ohms;
798                 Rt /= z1;
799                 Rt = (Rt + 2047) >> 12;
800         } else {
801                 Rt = 0;
802         }
803
804         /*
805          * Sample found inconsistent by debouncing or pressure is beyond
806          * the maximum. Don't report it to user space, repeat at least
807          * once more the measurement
808          */
809         if (packet->tc.ignore || Rt > ts->pressure_max) {
810                 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
811                          packet->tc.ignore, Rt);
812                 return;
813         }
814
815         /*
816          * Maybe check the pendown state before reporting. This discards
817          * false readings when the pen is lifted.
818          */
819         if (ts->penirq_recheck_delay_usecs) {
820                 udelay(ts->penirq_recheck_delay_usecs);
821                 if (!get_pendown_state(ts))
822                         Rt = 0;
823         }
824
825         /*
826          * NOTE: We can't rely on the pressure to determine the pen down
827          * state, even this controller has a pressure sensor. The pressure
828          * value can fluctuate for quite a while after lifting the pen and
829          * in some cases may not even settle at the expected value.
830          *
831          * The only safe way to check for the pen up condition is in the
832          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
833          */
834         if (Rt) {
835                 struct input_dev *input = ts->input;
836
837                 if (ts->swap_xy)
838                         swap(x, y);
839
840                 if (!ts->pendown) {
841                         input_report_key(input, BTN_TOUCH, 1);
842                         ts->pendown = true;
843                         dev_vdbg(&ts->spi->dev, "DOWN\n");
844                 }
845
846                 input_report_abs(input, ABS_X, x);
847                 input_report_abs(input, ABS_Y, y);
848                 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
849
850                 input_sync(input);
851                 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
852         }
853 }
854
855 static irqreturn_t ads7846_hard_irq(int irq, void *handle)
856 {
857         struct ads7846 *ts = handle;
858
859         return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
860 }
861
862
863 static irqreturn_t ads7846_irq(int irq, void *handle)
864 {
865         struct ads7846 *ts = handle;
866
867         /* Start with a small delay before checking pendown state */
868         msleep(TS_POLL_DELAY);
869
870         while (!ts->stopped && get_pendown_state(ts)) {
871
872                 /* pen is down, continue with the measurement */
873                 ads7846_read_state(ts);
874
875                 if (!ts->stopped)
876                         ads7846_report_state(ts);
877
878                 wait_event_timeout(ts->wait, ts->stopped,
879                                    msecs_to_jiffies(TS_POLL_PERIOD));
880         }
881
882         if (ts->pendown) {
883                 struct input_dev *input = ts->input;
884
885                 input_report_key(input, BTN_TOUCH, 0);
886                 input_report_abs(input, ABS_PRESSURE, 0);
887                 input_sync(input);
888
889                 ts->pendown = false;
890                 dev_vdbg(&ts->spi->dev, "UP\n");
891         }
892
893         return IRQ_HANDLED;
894 }
895
896 #ifdef CONFIG_PM_SLEEP
897 static int ads7846_suspend(struct device *dev)
898 {
899         struct ads7846 *ts = dev_get_drvdata(dev);
900
901         mutex_lock(&ts->lock);
902
903         if (!ts->suspended) {
904
905                 if (!ts->disabled)
906                         __ads7846_disable(ts);
907
908                 if (device_may_wakeup(&ts->spi->dev))
909                         enable_irq_wake(ts->spi->irq);
910
911                 ts->suspended = true;
912         }
913
914         mutex_unlock(&ts->lock);
915
916         return 0;
917 }
918
919 static int ads7846_resume(struct device *dev)
920 {
921         struct ads7846 *ts = dev_get_drvdata(dev);
922
923         mutex_lock(&ts->lock);
924
925         if (ts->suspended) {
926
927                 ts->suspended = false;
928
929                 if (device_may_wakeup(&ts->spi->dev))
930                         disable_irq_wake(ts->spi->irq);
931
932                 if (!ts->disabled)
933                         __ads7846_enable(ts);
934         }
935
936         mutex_unlock(&ts->lock);
937
938         return 0;
939 }
940 #endif
941
942 static SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
943
944 static int __devinit ads7846_setup_pendown(struct spi_device *spi, struct ads7846 *ts)
945 {
946         struct ads7846_platform_data *pdata = spi->dev.platform_data;
947         int err;
948
949         /*
950          * REVISIT when the irq can be triggered active-low, or if for some
951          * reason the touchscreen isn't hooked up, we don't need to access
952          * the pendown state.
953          */
954
955         if (pdata->get_pendown_state) {
956                 ts->get_pendown_state = pdata->get_pendown_state;
957         } else if (gpio_is_valid(pdata->gpio_pendown)) {
958
959                 err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
960                 if (err) {
961                         dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
962                                 pdata->gpio_pendown);
963                         return err;
964                 }
965
966                 ts->gpio_pendown = pdata->gpio_pendown;
967
968         } else {
969                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
970                 return -EINVAL;
971         }
972
973         return 0;
974 }
975
976 /*
977  * Set up the transfers to read touchscreen state; this assumes we
978  * use formula #2 for pressure, not #3.
979  */
980 static void __devinit ads7846_setup_spi_msg(struct ads7846 *ts,
981                                 const struct ads7846_platform_data *pdata)
982 {
983         struct spi_message *m = &ts->msg[0];
984         struct spi_transfer *x = ts->xfer;
985         struct ads7846_packet *packet = ts->packet;
986         int vref = pdata->keep_vref_on;
987
988         if (ts->model == 7873) {
989                 /*
990                  * The AD7873 is almost identical to the ADS7846
991                  * keep VREF off during differential/ratiometric
992                  * conversion modes.
993                  */
994                 ts->model = 7846;
995                 vref = 0;
996         }
997
998         ts->msg_count = 1;
999         spi_message_init(m);
1000         m->context = ts;
1001
1002         if (ts->model == 7845) {
1003                 packet->read_y_cmd[0] = READ_Y(vref);
1004                 packet->read_y_cmd[1] = 0;
1005                 packet->read_y_cmd[2] = 0;
1006                 x->tx_buf = &packet->read_y_cmd[0];
1007                 x->rx_buf = &packet->tc.y_buf[0];
1008                 x->len = 3;
1009                 spi_message_add_tail(x, m);
1010         } else {
1011                 /* y- still on; turn on only y+ (and ADC) */
1012                 packet->read_y = READ_Y(vref);
1013                 x->tx_buf = &packet->read_y;
1014                 x->len = 1;
1015                 spi_message_add_tail(x, m);
1016
1017                 x++;
1018                 x->rx_buf = &packet->tc.y;
1019                 x->len = 2;
1020                 spi_message_add_tail(x, m);
1021         }
1022
1023         /*
1024          * The first sample after switching drivers can be low quality;
1025          * optionally discard it, using a second one after the signals
1026          * have had enough time to stabilize.
1027          */
1028         if (pdata->settle_delay_usecs) {
1029                 x->delay_usecs = pdata->settle_delay_usecs;
1030
1031                 x++;
1032                 x->tx_buf = &packet->read_y;
1033                 x->len = 1;
1034                 spi_message_add_tail(x, m);
1035
1036                 x++;
1037                 x->rx_buf = &packet->tc.y;
1038                 x->len = 2;
1039                 spi_message_add_tail(x, m);
1040         }
1041
1042         ts->msg_count++;
1043         m++;
1044         spi_message_init(m);
1045         m->context = ts;
1046
1047         if (ts->model == 7845) {
1048                 x++;
1049                 packet->read_x_cmd[0] = READ_X(vref);
1050                 packet->read_x_cmd[1] = 0;
1051                 packet->read_x_cmd[2] = 0;
1052                 x->tx_buf = &packet->read_x_cmd[0];
1053                 x->rx_buf = &packet->tc.x_buf[0];
1054                 x->len = 3;
1055                 spi_message_add_tail(x, m);
1056         } else {
1057                 /* turn y- off, x+ on, then leave in lowpower */
1058                 x++;
1059                 packet->read_x = READ_X(vref);
1060                 x->tx_buf = &packet->read_x;
1061                 x->len = 1;
1062                 spi_message_add_tail(x, m);
1063
1064                 x++;
1065                 x->rx_buf = &packet->tc.x;
1066                 x->len = 2;
1067                 spi_message_add_tail(x, m);
1068         }
1069
1070         /* ... maybe discard first sample ... */
1071         if (pdata->settle_delay_usecs) {
1072                 x->delay_usecs = pdata->settle_delay_usecs;
1073
1074                 x++;
1075                 x->tx_buf = &packet->read_x;
1076                 x->len = 1;
1077                 spi_message_add_tail(x, m);
1078
1079                 x++;
1080                 x->rx_buf = &packet->tc.x;
1081                 x->len = 2;
1082                 spi_message_add_tail(x, m);
1083         }
1084
1085         /* turn y+ off, x- on; we'll use formula #2 */
1086         if (ts->model == 7846) {
1087                 ts->msg_count++;
1088                 m++;
1089                 spi_message_init(m);
1090                 m->context = ts;
1091
1092                 x++;
1093                 packet->read_z1 = READ_Z1(vref);
1094                 x->tx_buf = &packet->read_z1;
1095                 x->len = 1;
1096                 spi_message_add_tail(x, m);
1097
1098                 x++;
1099                 x->rx_buf = &packet->tc.z1;
1100                 x->len = 2;
1101                 spi_message_add_tail(x, m);
1102
1103                 /* ... maybe discard first sample ... */
1104                 if (pdata->settle_delay_usecs) {
1105                         x->delay_usecs = pdata->settle_delay_usecs;
1106
1107                         x++;
1108                         x->tx_buf = &packet->read_z1;
1109                         x->len = 1;
1110                         spi_message_add_tail(x, m);
1111
1112                         x++;
1113                         x->rx_buf = &packet->tc.z1;
1114                         x->len = 2;
1115                         spi_message_add_tail(x, m);
1116                 }
1117
1118                 ts->msg_count++;
1119                 m++;
1120                 spi_message_init(m);
1121                 m->context = ts;
1122
1123                 x++;
1124                 packet->read_z2 = READ_Z2(vref);
1125                 x->tx_buf = &packet->read_z2;
1126                 x->len = 1;
1127                 spi_message_add_tail(x, m);
1128
1129                 x++;
1130                 x->rx_buf = &packet->tc.z2;
1131                 x->len = 2;
1132                 spi_message_add_tail(x, m);
1133
1134                 /* ... maybe discard first sample ... */
1135                 if (pdata->settle_delay_usecs) {
1136                         x->delay_usecs = pdata->settle_delay_usecs;
1137
1138                         x++;
1139                         x->tx_buf = &packet->read_z2;
1140                         x->len = 1;
1141                         spi_message_add_tail(x, m);
1142
1143                         x++;
1144                         x->rx_buf = &packet->tc.z2;
1145                         x->len = 2;
1146                         spi_message_add_tail(x, m);
1147                 }
1148         }
1149
1150         /* power down */
1151         ts->msg_count++;
1152         m++;
1153         spi_message_init(m);
1154         m->context = ts;
1155
1156         if (ts->model == 7845) {
1157                 x++;
1158                 packet->pwrdown_cmd[0] = PWRDOWN;
1159                 packet->pwrdown_cmd[1] = 0;
1160                 packet->pwrdown_cmd[2] = 0;
1161                 x->tx_buf = &packet->pwrdown_cmd[0];
1162                 x->len = 3;
1163         } else {
1164                 x++;
1165                 packet->pwrdown = PWRDOWN;
1166                 x->tx_buf = &packet->pwrdown;
1167                 x->len = 1;
1168                 spi_message_add_tail(x, m);
1169
1170                 x++;
1171                 x->rx_buf = &packet->dummy;
1172                 x->len = 2;
1173         }
1174
1175         CS_CHANGE(*x);
1176         spi_message_add_tail(x, m);
1177 }
1178
1179 static int __devinit ads7846_probe(struct spi_device *spi)
1180 {
1181         struct ads7846 *ts;
1182         struct ads7846_packet *packet;
1183         struct input_dev *input_dev;
1184         struct ads7846_platform_data *pdata = spi->dev.platform_data;
1185         unsigned long irq_flags;
1186         int err;
1187
1188         if (!spi->irq) {
1189                 dev_dbg(&spi->dev, "no IRQ?\n");
1190                 return -ENODEV;
1191         }
1192
1193         if (!pdata) {
1194                 dev_dbg(&spi->dev, "no platform data?\n");
1195                 return -ENODEV;
1196         }
1197
1198         /* don't exceed max specified sample rate */
1199         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
1200                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
1201                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
1202                 return -EINVAL;
1203         }
1204
1205         /* We'd set TX word size 8 bits and RX word size to 13 bits ... except
1206          * that even if the hardware can do that, the SPI controller driver
1207          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
1208          */
1209         spi->bits_per_word = 8;
1210         spi->mode = SPI_MODE_0;
1211         err = spi_setup(spi);
1212         if (err < 0)
1213                 return err;
1214
1215         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
1216         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
1217         input_dev = input_allocate_device();
1218         if (!ts || !packet || !input_dev) {
1219                 err = -ENOMEM;
1220                 goto err_free_mem;
1221         }
1222
1223         dev_set_drvdata(&spi->dev, ts);
1224
1225         ts->packet = packet;
1226         ts->spi = spi;
1227         ts->input = input_dev;
1228         ts->vref_mv = pdata->vref_mv;
1229         ts->swap_xy = pdata->swap_xy;
1230
1231         mutex_init(&ts->lock);
1232         init_waitqueue_head(&ts->wait);
1233
1234         ts->model = pdata->model ? : 7846;
1235         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
1236         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
1237         ts->pressure_max = pdata->pressure_max ? : ~0;
1238
1239         if (pdata->filter != NULL) {
1240                 if (pdata->filter_init != NULL) {
1241                         err = pdata->filter_init(pdata, &ts->filter_data);
1242                         if (err < 0)
1243                                 goto err_free_mem;
1244                 }
1245                 ts->filter = pdata->filter;
1246                 ts->filter_cleanup = pdata->filter_cleanup;
1247         } else if (pdata->debounce_max) {
1248                 ts->debounce_max = pdata->debounce_max;
1249                 if (ts->debounce_max < 2)
1250                         ts->debounce_max = 2;
1251                 ts->debounce_tol = pdata->debounce_tol;
1252                 ts->debounce_rep = pdata->debounce_rep;
1253                 ts->filter = ads7846_debounce_filter;
1254                 ts->filter_data = ts;
1255         } else {
1256                 ts->filter = ads7846_no_filter;
1257         }
1258
1259         err = ads7846_setup_pendown(spi, ts);
1260         if (err)
1261                 goto err_cleanup_filter;
1262
1263         if (pdata->penirq_recheck_delay_usecs)
1264                 ts->penirq_recheck_delay_usecs =
1265                                 pdata->penirq_recheck_delay_usecs;
1266
1267         ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
1268
1269         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
1270         snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
1271
1272         input_dev->name = ts->name;
1273         input_dev->phys = ts->phys;
1274         input_dev->dev.parent = &spi->dev;
1275
1276         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
1277         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
1278         input_set_abs_params(input_dev, ABS_X,
1279                         pdata->x_min ? : 0,
1280                         pdata->x_max ? : MAX_12BIT,
1281                         0, 0);
1282         input_set_abs_params(input_dev, ABS_Y,
1283                         pdata->y_min ? : 0,
1284                         pdata->y_max ? : MAX_12BIT,
1285                         0, 0);
1286         input_set_abs_params(input_dev, ABS_PRESSURE,
1287                         pdata->pressure_min, pdata->pressure_max, 0, 0);
1288
1289         ads7846_setup_spi_msg(ts, pdata);
1290
1291         ts->reg = regulator_get(&spi->dev, "vcc");
1292         if (IS_ERR(ts->reg)) {
1293                 err = PTR_ERR(ts->reg);
1294                 dev_err(&spi->dev, "unable to get regulator: %d\n", err);
1295                 goto err_free_gpio;
1296         }
1297
1298         err = regulator_enable(ts->reg);
1299         if (err) {
1300                 dev_err(&spi->dev, "unable to enable regulator: %d\n", err);
1301                 goto err_put_regulator;
1302         }
1303
1304         irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
1305         irq_flags |= IRQF_ONESHOT;
1306
1307         err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq,
1308                                    irq_flags, spi->dev.driver->name, ts);
1309         if (err && !pdata->irq_flags) {
1310                 dev_info(&spi->dev,
1311                         "trying pin change workaround on irq %d\n", spi->irq);
1312                 irq_flags |= IRQF_TRIGGER_RISING;
1313                 err = request_threaded_irq(spi->irq,
1314                                   ads7846_hard_irq, ads7846_irq,
1315                                   irq_flags, spi->dev.driver->name, ts);
1316         }
1317
1318         if (err) {
1319                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1320                 goto err_disable_regulator;
1321         }
1322
1323         err = ads784x_hwmon_register(spi, ts);
1324         if (err)
1325                 goto err_free_irq;
1326
1327         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1328
1329         /*
1330          * Take a first sample, leaving nPENIRQ active and vREF off; avoid
1331          * the touchscreen, in case it's not connected.
1332          */
1333         if (ts->model == 7845)
1334                 ads7845_read12_ser(&spi->dev, PWRDOWN);
1335         else
1336                 (void) ads7846_read12_ser(&spi->dev,
1337                                 READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1338
1339         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1340         if (err)
1341                 goto err_remove_hwmon;
1342
1343         err = input_register_device(input_dev);
1344         if (err)
1345                 goto err_remove_attr_group;
1346
1347         device_init_wakeup(&spi->dev, pdata->wakeup);
1348
1349         return 0;
1350
1351  err_remove_attr_group:
1352         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1353  err_remove_hwmon:
1354         ads784x_hwmon_unregister(spi, ts);
1355  err_free_irq:
1356         free_irq(spi->irq, ts);
1357  err_disable_regulator:
1358         regulator_disable(ts->reg);
1359  err_put_regulator:
1360         regulator_put(ts->reg);
1361  err_free_gpio:
1362         if (!ts->get_pendown_state)
1363                 gpio_free(ts->gpio_pendown);
1364  err_cleanup_filter:
1365         if (ts->filter_cleanup)
1366                 ts->filter_cleanup(ts->filter_data);
1367  err_free_mem:
1368         input_free_device(input_dev);
1369         kfree(packet);
1370         kfree(ts);
1371         return err;
1372 }
1373
1374 static int __devexit ads7846_remove(struct spi_device *spi)
1375 {
1376         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
1377
1378         device_init_wakeup(&spi->dev, false);
1379
1380         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1381
1382         ads7846_disable(ts);
1383         free_irq(ts->spi->irq, ts);
1384
1385         input_unregister_device(ts->input);
1386
1387         ads784x_hwmon_unregister(spi, ts);
1388
1389         regulator_disable(ts->reg);
1390         regulator_put(ts->reg);
1391
1392         if (!ts->get_pendown_state) {
1393                 /*
1394                  * If we are not using specialized pendown method we must
1395                  * have been relying on gpio we set up ourselves.
1396                  */
1397                 gpio_free(ts->gpio_pendown);
1398         }
1399
1400         if (ts->filter_cleanup)
1401                 ts->filter_cleanup(ts->filter_data);
1402
1403         kfree(ts->packet);
1404         kfree(ts);
1405
1406         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1407
1408         return 0;
1409 }
1410
1411 static struct spi_driver ads7846_driver = {
1412         .driver = {
1413                 .name   = "ads7846",
1414                 .bus    = &spi_bus_type,
1415                 .owner  = THIS_MODULE,
1416                 .pm     = &ads7846_pm,
1417         },
1418         .probe          = ads7846_probe,
1419         .remove         = __devexit_p(ads7846_remove),
1420 };
1421
1422 static int __init ads7846_init(void)
1423 {
1424         return spi_register_driver(&ads7846_driver);
1425 }
1426 module_init(ads7846_init);
1427
1428 static void __exit ads7846_exit(void)
1429 {
1430         spi_unregister_driver(&ads7846_driver);
1431 }
1432 module_exit(ads7846_exit);
1433
1434 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1435 MODULE_LICENSE("GPL");
1436 MODULE_ALIAS("spi:ads7846");