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/device.h>
  21 #include <linux/init.h>
  22 #include <linux/delay.h>
  23 #include <linux/input.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/slab.h>
  26 #include <linux/spi/spi.h>
  27 #include <linux/spi/ads7846.h>
  28 #include <asm/irq.h>
  29
  30 #ifdef  CONFIG_ARM
  31 #include <asm/mach-types.h>
  32 #ifdef  CONFIG_ARCH_OMAP
  33 #include <asm/arch/gpio.h>
  34 #endif
  35 #endif
  36
  37
  38 /*
  39  * This code has been tested on an ads7846 / N770 device.
  40  * Support for ads7843 and ads7845 has only been stubbed in.
  41  *
  42  * Not yet done:  How accurate are the temperature and voltage
  43  * readings? (System-specific calibration should support
  44  * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.)
  45  *
  46  * IRQ handling needs a workaround because of a shortcoming in handling
  47  * edge triggered IRQs on some platforms like the OMAP1/2. These
  48  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  49  * have to maintain our own SW IRQ disabled status. This should be
  50  * removed as soon as the affected platform's IRQ handling is fixed.
  51  *
  52  * app note sbaa036 talks in more detail about accurate sampling...
  53  * that ought to help in situations like LCDs inducing noise (which
  54  * can also be helped by using synch signals) and more generally.
  55  * This driver tries to utilize the measures described in the app
  56  * note. The strength of filtering can be set in the board-* specific
  57  * files.
  58  */
  59
  60 #define TS_POLL_PERIOD  msecs_to_jiffies(10)
  61
  62 /* this driver doesn't aim at the peak continuous sample rate */
  63 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  64
  65 struct ts_event {
  66         /* For portability, we can't read 12 bit values using SPI (which
  67          * would make the controller deliver them as native byteorder u16
  68          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  69          * which need byteswapping then range adjustment.
  70          */
  71         __be16 x;
  72         __be16 y;
  73         __be16 z1, z2;
  74         int    ignore;
  75 };
  76
  77 struct ads7846 {
  78         struct input_dev        *input;
  79         char                    phys[32];
  80
  81         struct spi_device       *spi;
  82         u16                     model;
  83         u16                     vref_delay_usecs;
  84         u16                     x_plate_ohms;
  85         u16                     pressure_max;
  86
  87         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  88         u16                     dummy;          /* for the pwrdown read */
  89         struct ts_event         tc;
  90
  91         struct spi_transfer     xfer[10];
  92         struct spi_message      msg[5];
  93         struct spi_message      *last_msg;
  94         int                     msg_idx;
  95         int                     read_cnt;
  96         int                     read_rep;
  97         int                     last_read;
  98
  99         u16                     debounce_max;
 100         u16                     debounce_tol;
 101         u16                     debounce_rep;
 102
 103         spinlock_t              lock;
 104         struct timer_list       timer;          /* P: lock */
 105         unsigned                pendown:1;      /* P: lock */
 106         unsigned                pending:1;      /* P: lock */
 107 // FIXME remove "irq_disabled"
 108         unsigned                irq_disabled:1; /* P: lock */
 109         unsigned                disabled:1;
 110
 111         int                     (*get_pendown_state)(void);
 112 };
 113
 114 /* leave chip selected when we're done, for quicker re-select? */
 115 #if     0
 116 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 117 #else
 118 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 119 #endif
 120
 121 /*--------------------------------------------------------------------------*/
 122
 123 /* The ADS7846 has touchscreen and other sensors.
 124  * Earlier ads784x chips are somewhat compatible.
 125  */
 126 #define ADS_START               (1 << 7)
 127 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 128 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 129 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 130 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 131 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 132 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 133 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 134 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 135 #define ADS_8_BIT               (1 << 3)
 136 #define ADS_12_BIT              (0 << 3)
 137 #define ADS_SER                 (1 << 2)        /* non-differential */
 138 #define ADS_DFR                 (0 << 2)        /* differential */
 139 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 140 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 141 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 142 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 143
 144 #define MAX_12BIT       ((1<<12)-1)
 145
 146 /* leave ADC powered up (disables penirq) between differential samples */
 147 #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
 148         | ADS_12_BIT | ADS_DFR)
 149
 150 #define READ_Y  (READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON)
 151 #define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
 152 #define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
 153
 154 #define READ_X  (READ_12BIT_DFR(x)  | ADS_PD10_ADC_ON)
 155 #define PWRDOWN (READ_12BIT_DFR(y)  | ADS_PD10_PDOWN)   /* LAST */
 156
 157 /* single-ended samples need to first power up reference voltage;
 158  * we leave both ADC and VREF powered
 159  */
 160 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 161         | ADS_12_BIT | ADS_SER)
 162
 163 #define REF_ON  (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
 164 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
 165
 166 /*--------------------------------------------------------------------------*/
 167
 168 /*
 169  * Non-touchscreen sensors only use single-ended conversions.
 170  */
 171
 172 struct ser_req {
 173         u8                      ref_on;
 174         u8                      command;
 175         u8                      ref_off;
 176         u16                     scratch;
 177         __be16                  sample;
 178         struct spi_message      msg;
 179         struct spi_transfer     xfer[6];
 180 };
 181
 182 static void ads7846_enable(struct ads7846 *ts);
 183 static void ads7846_disable(struct ads7846 *ts);
 184
 185 static int device_suspended(struct device *dev)
 186 {
 187         struct ads7846 *ts = dev_get_drvdata(dev);
 188         return dev->power.power_state.event != PM_EVENT_ON || ts->disabled;
 189 }
 190
 191 static int ads7846_read12_ser(struct device *dev, unsigned command)
 192 {
 193         struct spi_device       *spi = to_spi_device(dev);
 194         struct ads7846          *ts = dev_get_drvdata(dev);
 195         struct ser_req          *req = kzalloc(sizeof *req, SLAB_KERNEL);
 196         int                     status;
 197         int                     sample;
 198         int                     i;
 199
 200         if (!req)
 201                 return -ENOMEM;
 202
 203         spi_message_init(&req->msg);
 204
 205         /* activate reference, so it has time to settle; */
 206         req->ref_on = REF_ON;
 207         req->xfer[0].tx_buf = &req->ref_on;
 208         req->xfer[0].len = 1;
 209         req->xfer[1].rx_buf = &req->scratch;
 210         req->xfer[1].len = 2;
 211
 212         /*
 213          * for external VREF, 0 usec (and assume it's always on);
 214          * for 1uF, use 800 usec;
 215          * no cap, 100 usec.
 216          */
 217         req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 218
 219         /* take sample */
 220         req->command = (u8) command;
 221         req->xfer[2].tx_buf = &req->command;
 222         req->xfer[2].len = 1;
 223         req->xfer[3].rx_buf = &req->sample;
 224         req->xfer[3].len = 2;
 225
 226         /* REVISIT:  take a few more samples, and compare ... */
 227
 228         /* turn off reference */
 229         req->ref_off = REF_OFF;
 230         req->xfer[4].tx_buf = &req->ref_off;
 231         req->xfer[4].len = 1;
 232         req->xfer[5].rx_buf = &req->scratch;
 233         req->xfer[5].len = 2;
 234
 235         CS_CHANGE(req->xfer[5]);
 236
 237         /* group all the transfers together, so we can't interfere with
 238          * reading touchscreen state; disable penirq while sampling
 239          */
 240         for (i = 0; i < 6; i++)
 241                 spi_message_add_tail(&req->xfer[i], &req->msg);
 242
 243         ts->irq_disabled = 1;
 244         disable_irq(spi->irq);
 245         status = spi_sync(spi, &req->msg);
 246         ts->irq_disabled = 0;
 247         enable_irq(spi->irq);
 248
 249         if (req->msg.status)
 250                 status = req->msg.status;
 251         sample = be16_to_cpu(req->sample);
 252         sample = sample >> 4;
 253         kfree(req);
 254
 255         return status ? status : sample;
 256 }
 257
 258 #define SHOW(name) static ssize_t \
 259 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 260 { \
 261         ssize_t v = ads7846_read12_ser(dev, \
 262                         READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
 263         if (v < 0) \
 264                 return v; \
 265         return sprintf(buf, "%u\n", (unsigned) v); \
 266 } \
 267 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 268
 269 SHOW(temp0)
 270 SHOW(temp1)
 271 SHOW(vaux)
 272 SHOW(vbatt)
 273
 274 static int is_pen_down(struct device *dev)
 275 {
 276         struct ads7846          *ts = dev_get_drvdata(dev);
 277
 278         return ts->pendown;
 279 }
 280
 281 static ssize_t ads7846_pen_down_show(struct device *dev,
 282                                      struct device_attribute *attr, char *buf)
 283 {
 284         return sprintf(buf, "%u\n", is_pen_down(dev));
 285 }
 286
 287 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 288
 289 static ssize_t ads7846_disable_show(struct device *dev,
 290                                      struct device_attribute *attr, char *buf)
 291 {
 292         struct ads7846  *ts = dev_get_drvdata(dev);
 293
 294         return sprintf(buf, "%u\n", ts->disabled);
 295 }
 296
 297 static ssize_t ads7846_disable_store(struct device *dev,
 298                                      struct device_attribute *attr,
 299                                      const char *buf, size_t count)
 300 {
 301         struct ads7846 *ts = dev_get_drvdata(dev);
 302         char *endp;
 303         int i;
 304
 305         i = simple_strtoul(buf, &endp, 10);
 306         spin_lock_irq(&ts->lock);
 307
 308         if (i)
 309                 ads7846_disable(ts);
 310         else
 311                 ads7846_enable(ts);
 312
 313         spin_unlock_irq(&ts->lock);
 314
 315         return count;
 316 }
 317
 318 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 319
 320 /*--------------------------------------------------------------------------*/
 321
 322 /*
 323  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 324  * to retrieve touchscreen status.
 325  *
 326  * The SPI transfer completion callback does the real work.  It reports
 327  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 328  */
 329
 330 static void ads7846_rx(void *ads)
 331 {
 332         struct ads7846          *ts = ads;
 333         struct input_dev        *input_dev = ts->input;
 334         unsigned                Rt;
 335         unsigned                sync = 0;
 336         u16                     x, y, z1, z2;
 337         unsigned long           flags;
 338
 339         /* adjust:  12 bit samples (left aligned), built from
 340          * two 8 bit values writen msb-first.
 341          */
 342         x = be16_to_cpu(ts->tc.x) >> 4;
 343         y = be16_to_cpu(ts->tc.y) >> 4;
 344         z1 = be16_to_cpu(ts->tc.z1) >> 4;
 345         z2 = be16_to_cpu(ts->tc.z2) >> 4;
 346
 347         /* range filtering */
 348         if (x == MAX_12BIT)
 349                 x = 0;
 350
 351         if (likely(x && z1 && !device_suspended(&ts->spi->dev))) {
 352                 /* compute touch pressure resistance using equation #2 */
 353                 Rt = z2;
 354                 Rt -= z1;
 355                 Rt *= x;
 356                 Rt *= ts->x_plate_ohms;
 357                 Rt /= z1;
 358                 Rt = (Rt + 2047) >> 12;
 359         } else
 360                 Rt = 0;
 361
 362         /* Sample found inconsistent by debouncing or pressure is beyond
 363         * the maximum. Don't report it to user space, repeat at least
 364         * once more the measurement */
 365         if (ts->tc.ignore || Rt > ts->pressure_max) {
 366                 mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
 367                 return;
 368         }
 369
 370         /* NOTE:  "pendown" is inferred from pressure; we don't rely on
 371          * being able to check nPENIRQ status, or "friendly" trigger modes
 372          * (both-edges is much better than just-falling or low-level).
 373          *
 374          * REVISIT:  some boards may require reading nPENIRQ; it's
 375          * needed on 7843.  and 7845 reads pressure differently...
 376          *
 377          * REVISIT:  the touchscreen might not be connected; this code
 378          * won't notice that, even if nPENIRQ never fires ...
 379          */
 380         if (!ts->pendown && Rt != 0) {
 381                 input_report_key(input_dev, BTN_TOUCH, 1);
 382                 sync = 1;
 383         } else if (ts->pendown && Rt == 0) {
 384                 input_report_key(input_dev, BTN_TOUCH, 0);
 385                 sync = 1;
 386         }
 387
 388         if (Rt) {
 389                 input_report_abs(input_dev, ABS_X, x);
 390                 input_report_abs(input_dev, ABS_Y, y);
 391                 sync = 1;
 392         }
 393
 394         if (sync) {
 395                 input_report_abs(input_dev, ABS_PRESSURE, Rt);
 396                 input_sync(input_dev);
 397         }
 398
 399 #ifdef  VERBOSE
 400         if (Rt || ts->pendown)
 401                 pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
 402                         x, y, Rt, Rt ? "" : " UP");
 403 #endif
 404
 405         spin_lock_irqsave(&ts->lock, flags);
 406
 407         ts->pendown = (Rt != 0);
 408         mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
 409
 410         spin_unlock_irqrestore(&ts->lock, flags);
 411 }
 412
 413 static void ads7846_debounce(void *ads)
 414 {
 415         struct ads7846          *ts = ads;
 416         struct spi_message      *m;
 417         struct spi_transfer     *t;
 418         int                     val;
 419         int                     status;
 420
 421         m = &ts->msg[ts->msg_idx];
 422         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 423         val = (*(u16 *)t->rx_buf) >> 3;
 424         if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
 425                 /* Repeat it, if this was the first read or the read
 426                  * wasn't consistent enough. */
 427                 if (ts->read_cnt < ts->debounce_max) {
 428                         ts->last_read = val;
 429                         ts->read_cnt++;
 430                 } else {
 431                         /* Maximum number of debouncing reached and still
 432                          * not enough number of consistent readings. Abort
 433                          * the whole sample, repeat it in the next sampling
 434                          * period.
 435                          */
 436                         ts->tc.ignore = 1;
 437                         ts->read_cnt = 0;
 438                         /* Last message will contain ads7846_rx() as the
 439                          * completion function.
 440                          */
 441                         m = ts->last_msg;
 442                 }
 443                 /* Start over collecting consistent readings. */
 444                 ts->read_rep = 0;
 445         } else {
 446                 if (++ts->read_rep > ts->debounce_rep) {
 447                         /* Got a good reading for this coordinate,
 448                          * go for the next one. */
 449                         ts->tc.ignore = 0;
 450                         ts->msg_idx++;
 451                         ts->read_cnt = 0;
 452                         ts->read_rep = 0;
 453                         m++;
 454                 } else
 455                         /* Read more values that are consistent. */
 456                         ts->read_cnt++;
 457         }
 458         status = spi_async(ts->spi, m);
 459         if (status)
 460                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 461                                 status);
 462 }
 463
 464 static void ads7846_timer(unsigned long handle)
 465 {
 466         struct ads7846  *ts = (void *)handle;
 467         int             status = 0;
 468
 469         spin_lock_irq(&ts->lock);
 470
 471         if (unlikely(ts->msg_idx && !ts->pendown)) {
 472                 /* measurment cycle ended */
 473                 if (!device_suspended(&ts->spi->dev)) {
 474                         ts->irq_disabled = 0;
 475                         enable_irq(ts->spi->irq);
 476                 }
 477                 ts->pending = 0;
 478                 ts->msg_idx = 0;
 479         } else {
 480                 /* pen is still down, continue with the measurement */
 481                 ts->msg_idx = 0;
 482                 status = spi_async(ts->spi, &ts->msg[0]);
 483                 if (status)
 484                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 485         }
 486
 487         spin_unlock_irq(&ts->lock);
 488 }
 489
 490 static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
 491 {
 492         struct ads7846 *ts = handle;
 493         unsigned long flags;
 494
 495         spin_lock_irqsave(&ts->lock, flags);
 496         if (likely(ts->get_pendown_state())) {
 497                 if (!ts->irq_disabled) {
 498                         /* REVISIT irq logic for many ARM chips has cloned a
 499                          * bug wherein disabling an irq in its handler won't
 500                          * work;(it's disabled lazily, and too late to work.
 501                          * until all their irq logic is fixed, we must shadow
 502                          * that state here.
 503                          */
 504                         ts->irq_disabled = 1;
 505                         disable_irq(ts->spi->irq);
 506                         ts->pending = 1;
 507                         mod_timer(&ts->timer, jiffies);
 508                 }
 509         }
 510         spin_unlock_irqrestore(&ts->lock, flags);
 511
 512         return IRQ_HANDLED;
 513 }
 514
 515 /*--------------------------------------------------------------------------*/
 516
 517 /* Must be called with ts->lock held */
 518 static void ads7846_disable(struct ads7846 *ts)
 519 {
 520         if (ts->disabled)
 521                 return;
 522
 523         ts->disabled = 1;
 524
 525         /* are we waiting for IRQ, or polling? */
 526         if (!ts->pending) {
 527                 ts->irq_disabled = 1;
 528                 disable_irq(ts->spi->irq);
 529         } else {
 530                 /* the timer will run at least once more, and
 531                  * leave everything in a clean state, IRQ disabled
 532                  */
 533                 while (ts->pending) {
 534                         spin_unlock_irq(&ts->lock);
 535                         msleep(1);
 536                         spin_lock_irq(&ts->lock);
 537                 }
 538         }
 539
 540         /* we know the chip's in lowpower mode since we always
 541          * leave it that way after every request
 542          */
 543
 544 }
 545
 546 /* Must be called with ts->lock held */
 547 static void ads7846_enable(struct ads7846 *ts)
 548 {
 549         if (!ts->disabled)
 550                 return;
 551
 552         ts->disabled = 0;
 553         ts->irq_disabled = 0;
 554         enable_irq(ts->spi->irq);
 555 }
 556
 557 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 558 {
 559         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 560
 561         spin_lock_irq(&ts->lock);
 562
 563         spi->dev.power.power_state = message;
 564         ads7846_disable(ts);
 565
 566         spin_unlock_irq(&ts->lock);
 567
 568         return 0;
 569
 570 }
 571
 572 static int ads7846_resume(struct spi_device *spi)
 573 {
 574         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 575
 576         spin_lock_irq(&ts->lock);
 577
 578         spi->dev.power.power_state = PMSG_ON;
 579         ads7846_enable(ts);
 580
 581         spin_unlock_irq(&ts->lock);
 582
 583         return 0;
 584 }
 585
 586 static int __devinit ads7846_probe(struct spi_device *spi)
 587 {
 588         struct ads7846                  *ts;
 589         struct input_dev                *input_dev;
 590         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 591         struct spi_message              *m;
 592         struct spi_transfer             *x;
 593         int                             err;
 594
 595         if (!spi->irq) {
 596                 dev_dbg(&spi->dev, "no IRQ?\n");
 597                 return -ENODEV;
 598         }
 599
 600         if (!pdata) {
 601                 dev_dbg(&spi->dev, "no platform data?\n");
 602                 return -ENODEV;
 603         }
 604
 605         /* don't exceed max specified sample rate */
 606         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 607                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 608                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 609                 return -EINVAL;
 610         }
 611
 612         if (pdata->get_pendown_state == NULL) {
 613                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 614                 return -EINVAL;
 615         }
 616
 617         /* We'd set the wordsize to 12 bits ... except that some controllers
 618          * will then treat the 8 bit command words as 12 bits (and drop the
 619          * four MSBs of the 12 bit result).  Result: inputs must be shifted
 620          * to discard the four garbage LSBs.
 621          */
 622
 623         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 624         input_dev = input_allocate_device();
 625         if (!ts || !input_dev) {
 626                 err = -ENOMEM;
 627                 goto err_free_mem;
 628         }
 629
 630         dev_set_drvdata(&spi->dev, ts);
 631         spi->dev.power.power_state = PMSG_ON;
 632
 633         ts->spi = spi;
 634         ts->input = input_dev;
 635
 636         init_timer(&ts->timer);
 637         ts->timer.data = (unsigned long) ts;
 638         ts->timer.function = ads7846_timer;
 639
 640         spin_lock_init(&ts->lock);
 641
 642         ts->model = pdata->model ? : 7846;
 643         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 644         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 645         ts->pressure_max = pdata->pressure_max ? : ~0;
 646         if (pdata->debounce_max) {
 647                 ts->debounce_max = pdata->debounce_max;
 648                 ts->debounce_tol = pdata->debounce_tol;
 649                 ts->debounce_rep = pdata->debounce_rep;
 650                 if (ts->debounce_rep > ts->debounce_max + 1)
 651                         ts->debounce_rep = ts->debounce_max - 1;
 652         } else
 653                 ts->debounce_tol = ~0;
 654         ts->get_pendown_state = pdata->get_pendown_state;
 655
 656         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 657
 658         input_dev->name = "ADS784x Touchscreen";
 659         input_dev->phys = ts->phys;
 660         input_dev->cdev.dev = &spi->dev;
 661
 662         input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 663         input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 664         input_set_abs_params(input_dev, ABS_X,
 665                         pdata->x_min ? : 0,
 666                         pdata->x_max ? : MAX_12BIT,
 667                         0, 0);
 668         input_set_abs_params(input_dev, ABS_Y,
 669                         pdata->y_min ? : 0,
 670                         pdata->y_max ? : MAX_12BIT,
 671                         0, 0);
 672         input_set_abs_params(input_dev, ABS_PRESSURE,
 673                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 674
 675         /* set up the transfers to read touchscreen state; this assumes we
 676          * use formula #2 for pressure, not #3.
 677          */
 678         m = &ts->msg[0];
 679         x = ts->xfer;
 680
 681         spi_message_init(m);
 682
 683         /* y- still on; turn on only y+ (and ADC) */
 684         ts->read_y = READ_Y;
 685         x->tx_buf = &ts->read_y;
 686         x->len = 1;
 687         spi_message_add_tail(x, m);
 688
 689         x++;
 690         x->rx_buf = &ts->tc.y;
 691         x->len = 2;
 692         spi_message_add_tail(x, m);
 693
 694         m->complete = ads7846_debounce;
 695         m->context = ts;
 696
 697         m++;
 698         spi_message_init(m);
 699
 700         /* turn y- off, x+ on, then leave in lowpower */
 701         x++;
 702         ts->read_x = READ_X;
 703         x->tx_buf = &ts->read_x;
 704         x->len = 1;
 705         spi_message_add_tail(x, m);
 706
 707         x++;
 708         x->rx_buf = &ts->tc.x;
 709         x->len = 2;
 710         spi_message_add_tail(x, m);
 711
 712         m->complete = ads7846_debounce;
 713         m->context = ts;
 714
 715         /* turn y+ off, x- on; we'll use formula #2 */
 716         if (ts->model == 7846) {
 717                 m++;
 718                 spi_message_init(m);
 719
 720                 x++;
 721                 ts->read_z1 = READ_Z1;
 722                 x->tx_buf = &ts->read_z1;
 723                 x->len = 1;
 724                 spi_message_add_tail(x, m);
 725
 726                 x++;
 727                 x->rx_buf = &ts->tc.z1;
 728                 x->len = 2;
 729                 spi_message_add_tail(x, m);
 730
 731                 m->complete = ads7846_debounce;
 732                 m->context = ts;
 733
 734                 m++;
 735                 spi_message_init(m);
 736
 737                 x++;
 738                 ts->read_z2 = READ_Z2;
 739                 x->tx_buf = &ts->read_z2;
 740                 x->len = 1;
 741                 spi_message_add_tail(x, m);
 742
 743                 x++;
 744                 x->rx_buf = &ts->tc.z2;
 745                 x->len = 2;
 746                 spi_message_add_tail(x, m);
 747
 748                 m->complete = ads7846_debounce;
 749                 m->context = ts;
 750         }
 751
 752         /* power down */
 753         m++;
 754         spi_message_init(m);
 755
 756         x++;
 757         ts->pwrdown = PWRDOWN;
 758         x->tx_buf = &ts->pwrdown;
 759         x->len = 1;
 760         spi_message_add_tail(x, m);
 761
 762         x++;
 763         x->rx_buf = &ts->dummy;
 764         x->len = 2;
 765         CS_CHANGE(*x);
 766         spi_message_add_tail(x, m);
 767
 768         m->complete = ads7846_rx;
 769         m->context = ts;
 770
 771         ts->last_msg = m;
 772
 773         if (request_irq(spi->irq, ads7846_irq,
 774                         SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING,
 775                         spi->dev.bus_id, ts)) {
 776                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
 777                 err = -EBUSY;
 778                 goto err_free_mem;
 779         }
 780
 781         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
 782
 783         /* take a first sample, leaving nPENIRQ active; avoid
 784          * the touchscreen, in case it's not connected.
 785          */
 786         (void) ads7846_read12_ser(&spi->dev,
 787                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
 788
 789         /* ads7843/7845 don't have temperature sensors, and
 790          * use the other sensors a bit differently too
 791          */
 792         if (ts->model == 7846) {
 793                 device_create_file(&spi->dev, &dev_attr_temp0);
 794                 device_create_file(&spi->dev, &dev_attr_temp1);
 795         }
 796         if (ts->model != 7845)
 797                 device_create_file(&spi->dev, &dev_attr_vbatt);
 798         device_create_file(&spi->dev, &dev_attr_vaux);
 799
 800         device_create_file(&spi->dev, &dev_attr_pen_down);
 801
 802         device_create_file(&spi->dev, &dev_attr_disable);
 803
 804         err = input_register_device(input_dev);
 805         if (err)
 806                 goto err_remove_attr;
 807
 808         return 0;
 809
 810  err_remove_attr:
 811         device_remove_file(&spi->dev, &dev_attr_disable);
 812         device_remove_file(&spi->dev, &dev_attr_pen_down);
 813         if (ts->model == 7846) {
 814                 device_remove_file(&spi->dev, &dev_attr_temp1);
 815                 device_remove_file(&spi->dev, &dev_attr_temp0);
 816         }
 817         if (ts->model != 7845)
 818                 device_remove_file(&spi->dev, &dev_attr_vbatt);
 819         device_remove_file(&spi->dev, &dev_attr_vaux);
 820
 821         free_irq(spi->irq, ts);
 822  err_free_mem:
 823         input_free_device(input_dev);
 824         kfree(ts);
 825         return err;
 826 }
 827
 828 static int __devexit ads7846_remove(struct spi_device *spi)
 829 {
 830         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
 831
 832         input_unregister_device(ts->input);
 833
 834         ads7846_suspend(spi, PMSG_SUSPEND);
 835
 836         device_remove_file(&spi->dev, &dev_attr_disable);
 837         device_remove_file(&spi->dev, &dev_attr_pen_down);
 838         if (ts->model == 7846) {
 839                 device_remove_file(&spi->dev, &dev_attr_temp1);
 840                 device_remove_file(&spi->dev, &dev_attr_temp0);
 841         }
 842         if (ts->model != 7845)
 843                 device_remove_file(&spi->dev, &dev_attr_vbatt);
 844         device_remove_file(&spi->dev, &dev_attr_vaux);
 845
 846         free_irq(ts->spi->irq, ts);
 847         /* suspend left the IRQ disabled */
 848         enable_irq(ts->spi->irq);
 849
 850         kfree(ts);
 851
 852         dev_dbg(&spi->dev, "unregistered touchscreen\n");
 853         return 0;
 854 }
 855
 856 static struct spi_driver ads7846_driver = {
 857         .driver = {
 858                 .name   = "ads7846",
 859                 .bus    = &spi_bus_type,
 860                 .owner  = THIS_MODULE,
 861         },
 862         .probe          = ads7846_probe,
 863         .remove         = __devexit_p(ads7846_remove),
 864         .suspend        = ads7846_suspend,
 865         .resume         = ads7846_resume,
 866 };
 867
 868 static int __init ads7846_init(void)
 869 {
 870         /* grr, board-specific init should stay out of drivers!! */
 871
 872 #ifdef  CONFIG_ARCH_OMAP
 873         if (machine_is_omap_osk()) {
 874                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
 875                 omap_request_gpio(4);
 876                 omap_set_gpio_direction(4, 1);
 877                 omap_request_gpio(6);
 878                 omap_set_gpio_direction(6, 1);
 879         }
 880         // also TI 1510 Innovator, bitbanging through FPGA
 881         // also Nokia 770
 882         // also Palm Tungsten T2
 883 #endif
 884
 885         // PXA:
 886         // also Dell Axim X50
 887         // also HP iPaq H191x/H192x/H415x/H435x
 888         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
 889         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
 890
 891         // Atmel at91sam9261-EK uses ads7843
 892
 893         // also various AMD Au1x00 devel boards
 894
 895         return spi_register_driver(&ads7846_driver);
 896 }
 897 module_init(ads7846_init);
 898
 899 static void __exit ads7846_exit(void)
 900 {
 901         spi_unregister_driver(&ads7846_driver);
 902
 903 #ifdef  CONFIG_ARCH_OMAP
 904         if (machine_is_omap_osk()) {
 905                 omap_free_gpio(4);
 906                 omap_free_gpio(6);
 907         }
 908 #endif
 909
 910 }
 911 module_exit(ads7846_exit);
 912
 913 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
 914 MODULE_LICENSE("GPL");