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