drivers/input/touchscreen/ads7846.c

   1 /*
   2  * ADS7846 based touchscreen and sensor driver
   3  *
   4  * Copyright (c) 2005 David Brownell
   5  * Copyright (c) 2006 Imre Deak <imre.deak@nokia.com>
   6  *
   7  * Using code from:
   8  *  - corgi_ts.c
   9  *      Copyright (C) 2004-2005 Richard Purdie
  10  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  11  *      Copyright (C) 2002 MontaVista Software
  12  *      Copyright (C) 2004 Texas Instruments
  13  *      Copyright (C) 2005 Dirk Behme
  14  *
  15  *  This program is free software; you can redistribute it and/or modify
  16  *  it under the terms of the GNU General Public License version 2 as
  17  *  published by the Free Software Foundation.
  18  */
  19 #include <linux/device.h>
  20 #include <linux/init.h>
  21 #include <linux/delay.h>
  22 #include <linux/input.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/slab.h>
  25 #include <linux/spi/spi.h>
  26 #include <linux/spi/ads7846.h>
  27
  28 #ifdef  CONFIG_ARM
  29 #include <asm/mach-types.h>
  30 #ifdef  CONFIG_ARCH_OMAP
  31 #include <asm/arch/gpio.h>
  32 #endif
  33 #endif
  34
  35
  36 /*
  37  * This code has been heavily tested on a Nokia 770, and lightly
  38  * tested on an other ads7846 device.
  39  * Support for ads7843 and ads7845 has only been stubbed in.
  40  *
  41  * Not yet done:  How accurate are the temperature and voltage
  42  * readings? (System-specific calibration should support
  43  * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.)
  44  *
  45  * IRQ handling needs a workaround because of a shortcoming in handling
  46  * edge triggered IRQs on some platforms like the OMAP1/2. These
  47  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  48  * have to maintain our own SW IRQ disabled status. This should be
  49  * removed as soon as the affected platforms' IRQ handling is fixed.
  50  *
  51  * app note sbaa036 talks in more detail about accurate sampling...
  52  * that ought to help in situations like LCDs inducing noise (which
  53  * can also be helped by using synch signals) and more generally.
  54  * This driver tries to utilize the measures described in the app
  55  * note. The strength of filtering can be set in the board-* specific
  56  * files.
  57  */
  58
  59 #define TS_POLL_PERIOD  msecs_to_jiffies(10)
  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         /* For portability, we can't read 12 bit values using SPI (which
  66          * would make the controller deliver them as native byteorder u16
  67          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  68          * which need byteswapping then range adjustment.
  69          */
  70         __be16 x;
  71         __be16 y;
  72         __be16 z1, z2;
  73 };
  74
  75 struct ads7846 {
  76         struct input_dev        *input;
  77         char                    phys[32];
  78
  79         struct spi_device       *spi;
  80         u16                     model;
  81         u16                     vref_delay_usecs;
  82         u16                     x_plate_ohms;
  83         u16                     pressure_max;
  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         u16                     last_x;
  89         u16                     last_y;
  90         u16                     last_pressure;
  91
  92         struct spi_transfer     xfer[10];
  93         struct spi_message      msg[5];
  94         int                     msg_idx;
  95         int                     read_cnt;
  96         int                     last_read;
  97
  98         u16                     debounce_max;
  99         u16                     debounce_tol;
 100
 101         spinlock_t              lock;
 102         struct timer_list       timer;          /* P: lock */
 103         unsigned                pendown:1;      /* P: lock */
 104         unsigned                pending:1;      /* P: lock */
 105 // FIXME remove "irq_disabled"
 106         unsigned                irq_disabled:1; /* P: lock */
 107         unsigned                disabled:1;
 108 };
 109
 110 /* leave chip selected when we're done, for quicker re-select? */
 111 #if     0
 112 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 113 #else
 114 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 115 #endif
 116
 117 /*--------------------------------------------------------------------------*/
 118
 119 /* The ADS7846 has touchscreen and other sensors.
 120  * Earlier ads784x chips are somewhat compatible.
 121  */
 122 #define ADS_START               (1 << 7)
 123 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 124 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 125 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 126 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 127 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 128 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 129 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 130 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 131 #define ADS_8_BIT               (1 << 3)
 132 #define ADS_12_BIT              (0 << 3)
 133 #define ADS_SER                 (1 << 2)        /* non-differential */
 134 #define ADS_DFR                 (0 << 2)        /* differential */
 135 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 136 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 137 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 138 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 139
 140 #define MAX_12BIT       ((1<<12)-1)
 141
 142 /* leave ADC powered up (disables penirq) between differential samples */
 143 #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
 144         | ADS_12_BIT | ADS_DFR)
 145
 146 #define READ_Y  (READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON)
 147 #define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
 148 #define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
 149
 150 #define READ_X  (READ_12BIT_DFR(x)  | ADS_PD10_ADC_ON)
 151 #define PWRDOWN (READ_12BIT_DFR(y)  | ADS_PD10_PDOWN)   /* LAST */
 152
 153 /* single-ended samples need to first power up reference voltage;
 154  * we leave both ADC and VREF powered
 155  */
 156 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 157         | ADS_12_BIT | ADS_SER)
 158
 159 #define REF_ON  (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
 160 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
 161
 162 /*--------------------------------------------------------------------------*/
 163
 164 /*
 165  * Non-touchscreen sensors only use single-ended conversions.
 166  */
 167
 168 struct ser_req {
 169         u8                      ref_on;
 170         u8                      command;
 171         u8                      ref_off;
 172         u16                     scratch;
 173         __be16                  sample;
 174         struct spi_message      msg;
 175         struct spi_transfer     xfer[6];
 176 };
 177
 178 static void ads7846_enable(struct ads7846 *ts);
 179 static void ads7846_disable(struct ads7846 *ts);
 180
 181 static int ads7846_read12_ser(struct device *dev, unsigned command)
 182 {
 183         struct spi_device       *spi = to_spi_device(dev);
 184         struct ads7846          *ts = dev_get_drvdata(dev);
 185         struct ser_req          *req = kzalloc(sizeof *req, SLAB_KERNEL);
 186         int                     status;
 187         int                     sample;
 188         int                     i;
 189
 190         if (!req)
 191                 return -ENOMEM;
 192
 193         spi_message_init(&req->msg);
 194
 195         /* activate reference, so it has time to settle; */
 196         req->ref_on = REF_ON;
 197         req->xfer[0].tx_buf = &req->ref_on;
 198         req->xfer[0].len = 1;
 199         req->xfer[1].rx_buf = &req->scratch;
 200         req->xfer[1].len = 2;
 201
 202         /*
 203          * for external VREF, 0 usec (and assume it's always on);
 204          * for 1uF, use 800 usec;
 205          * no cap, 100 usec.
 206          */
 207         req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 208
 209         /* take sample */
 210         req->command = (u8) command;
 211         req->xfer[2].tx_buf = &req->command;
 212         req->xfer[2].len = 1;
 213         req->xfer[3].rx_buf = &req->sample;
 214         req->xfer[3].len = 2;
 215
 216         /* REVISIT:  take a few more samples, and compare ... */
 217
 218         /* turn off reference */
 219         req->ref_off = REF_OFF;
 220         req->xfer[4].tx_buf = &req->ref_off;
 221         req->xfer[4].len = 1;
 222         req->xfer[5].rx_buf = &req->scratch;
 223         req->xfer[5].len = 2;
 224
 225         CS_CHANGE(req->xfer[5]);
 226
 227         /* group all the transfers together, so we can't interfere with
 228          * reading touchscreen state; disable penirq while sampling
 229          */
 230         for (i = 0; i < 6; i++)
 231                 spi_message_add_tail(&req->xfer[i], &req->msg);
 232
 233         disable_irq(spi->irq);
 234         status = spi_sync(spi, &req->msg);
 235         enable_irq(spi->irq);
 236
 237         if (req->msg.status)
 238                 status = req->msg.status;
 239         sample = be16_to_cpu(req->sample);
 240         sample = sample >> 4;
 241         kfree(req);
 242
 243         return status ? status : sample;
 244 }
 245
 246 #define SHOW(name) static ssize_t \
 247 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 248 { \
 249         ssize_t v = ads7846_read12_ser(dev, \
 250                         READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
 251         if (v < 0) \
 252                 return v; \
 253         return sprintf(buf, "%u\n", (unsigned) v); \
 254 } \
 255 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 256
 257 SHOW(temp0)
 258 SHOW(temp1)
 259 SHOW(vaux)
 260 SHOW(vbatt)
 261
 262 static int is_pen_down(struct device *dev)
 263 {
 264         struct ads7846          *ts = dev_get_drvdata(dev);
 265
 266         return ts->pendown;
 267 }
 268
 269 static ssize_t ads7846_pen_down_show(struct device *dev,
 270                                      struct device_attribute *attr, char *buf)
 271 {
 272         return sprintf(buf, "%u\n", is_pen_down(dev));
 273 }
 274
 275 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 276
 277 static ssize_t ads7846_disable_show(struct device *dev,
 278                                      struct device_attribute *attr, char *buf)
 279 {
 280         struct ads7846  *ts = dev_get_drvdata(dev);
 281
 282         return sprintf(buf, "%u\n", ts->disabled);
 283 }
 284
 285 static ssize_t ads7846_disable_store(struct device *dev,
 286                                      struct device_attribute *attr,
 287                                      const char *buf, size_t count)
 288 {
 289         struct ads7846 *ts = dev_get_drvdata(dev);
 290         unsigned long flags;
 291         char *endp;
 292         int i;
 293
 294         i = simple_strtoul(buf, &endp, 10);
 295         spin_lock_irqsave(&ts->lock, flags);
 296
 297         if (i)
 298                 ads7846_disable(ts);
 299         else
 300                 ads7846_enable(ts);
 301
 302         spin_unlock_irqrestore(&ts->lock, flags);
 303
 304         return count;
 305 }
 306
 307 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 308
 309 /*--------------------------------------------------------------------------*/
 310
 311 /*
 312  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 313  * to retrieve touchscreen status.
 314  *
 315  * The SPI transfer completion callback does the real work.  It reports
 316  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 317  */
 318
 319 static void ads7846_rx(void *ads)
 320 {
 321         struct ads7846          *ts = ads;
 322         struct input_dev        *input_dev = ts->input;
 323         unsigned                Rt;
 324         unsigned                sync = 0;
 325         u16                     x, y, z1, z2;
 326         unsigned long           flags;
 327
 328         /* adjust:  12 bit samples (left aligned), built from
 329          * two 8 bit values writen msb-first.
 330          */
 331         x = ts->tc.x >> 3;
 332         y = ts->tc.y >> 3;
 333         z1 = ts->tc.z1 >> 3;
 334         z2 = ts->tc.z2 >> 3;
 335
 336         /* range filtering */
 337         if (x == MAX_12BIT)
 338                 x = 0;
 339
 340         if (x && z1 && ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
 341                 /* compute touch pressure resistance using equation #2 */
 342                 Rt = z2;
 343                 Rt -= z1;
 344                 Rt *= x;
 345                 Rt *= ts->x_plate_ohms;
 346                 Rt /= z1;
 347                 Rt = (Rt + 2047) >> 12;
 348         } else
 349                 Rt = 0;
 350
 351         if (Rt > ts->pressure_max) {
 352                 if (ts->last_pressure) {
 353                         x = ts->last_x;
 354                         y = ts->last_y;
 355                 }
 356                 Rt = ts->pressure_max;
 357         }
 358
 359         ts->last_x = x;
 360         ts->last_y = y;
 361         ts->last_pressure = Rt;
 362
 363         /* NOTE:  "pendown" is inferred from pressure; we don't rely on
 364          * being able to check nPENIRQ status, or "friendly" trigger modes
 365          * (both-edges is much better than just-falling or low-level).
 366          *
 367          * REVISIT:  some boards may require reading nPENIRQ; it's
 368          * needed on 7843.  and 7845 reads pressure differently...
 369          *
 370          * REVISIT:  the touchscreen might not be connected; this code
 371          * won't notice that, even if nPENIRQ never fires ...
 372          */
 373         if (!ts->pendown && Rt != 0) {
 374                 input_report_key(input_dev, BTN_TOUCH, 1);
 375                 sync = 1;
 376         } else if (ts->pendown && Rt == 0) {
 377                 input_report_key(input_dev, BTN_TOUCH, 0);
 378                 sync = 1;
 379         }
 380
 381         if (Rt) {
 382                 input_report_abs(input_dev, ABS_X, x);
 383                 input_report_abs(input_dev, ABS_Y, y);
 384                 input_report_abs(input_dev, ABS_PRESSURE, Rt);
 385                 sync = 1;
 386         }
 387         if (sync)
 388                 input_sync(input_dev);
 389
 390 #ifdef  VERBOSE
 391         if (Rt || ts->pendown)
 392                 pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
 393                         x, y, Rt, Rt ? "" : " UP");
 394 #endif
 395
 396         /* don't retrigger while we're suspended */
 397         spin_lock_irqsave(&ts->lock, flags);
 398
 399         ts->pendown = (Rt != 0);
 400         ts->pending = 0;
 401
 402         if (ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
 403                 if (ts->pendown)
 404                         mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
 405                 else if (ts->irq_disabled) {
 406                         ts->irq_disabled = 0;
 407                         enable_irq(ts->spi->irq);
 408                 }
 409         }
 410
 411         spin_unlock_irqrestore(&ts->lock, flags);
 412 }
 413
 414 static void ads7846_debounce(void *ads)
 415 {
 416         struct ads7846          *ts = ads;
 417         struct spi_message      *m;
 418         struct spi_transfer     *t;
 419         u16                     val;
 420         int                     status;
 421
 422         m = &ts->msg[ts->msg_idx];
 423         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 424         val = (*(u16 *)t->rx_buf) >> 3;
 425
 426         if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol &&
 427                               ts->read_cnt < ts->debounce_max)) {
 428                 /* Repeat it, if this was the first read or the read wasn't
 429                  * consistent enough */
 430                 ts->read_cnt++;
 431                 ts->last_read = val;
 432         } else {
 433                 /* Go for the next read */
 434                 ts->msg_idx++;
 435                 ts->read_cnt = 0;
 436                 m++;
 437         }
 438         status = spi_async(ts->spi, m);
 439         if (status)
 440                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 441                                 status);
 442 }
 443
 444 static void ads7846_timer(unsigned long handle)
 445 {
 446         struct ads7846  *ts = (void *)handle;
 447         int             status = 0;
 448
 449         ts->msg_idx = 0;
 450         status = spi_async(ts->spi, &ts->msg[0]);
 451         if (status)
 452                 dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 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->irq_disabled && !ts->disabled)) {
 462                 if (!ts->irq_disabled) {
 463                         ts->irq_disabled = 1;
 464                         /* The following has at the moment no effect whatsoever
 465                          * on OMAP, that's why we maintain the disabled
 466                          * state ourselves */
 467                         disable_irq(ts->spi->irq);
 468                 }
 469                 if (!ts->pending) {
 470                         ts->pending = 1;
 471                         mod_timer(&ts->timer, jiffies);
 472                 }
 473         }
 474         spin_unlock_irqrestore(&ts->lock, flags);
 475
 476         return IRQ_HANDLED;
 477 }
 478
 479 /*--------------------------------------------------------------------------*/
 480
 481 /* Must be called with ts->lock held */
 482 static void ads7846_disable(struct ads7846 *ts)
 483 {
 484         if (ts->disabled)
 485                 return;
 486
 487         /* are we waiting for IRQ, or polling? */
 488         if (!ts->pendown) {
 489                 if (!ts->irq_disabled) {
 490                         ts->irq_disabled = 1;
 491                         disable_irq(ts->spi->irq);
 492                 }
 493         } else {
 494                 unsigned long flags;
 495
 496                 /* polling; force a final SPI completion;
 497                  * that will clean things up neatly
 498                  */
 499                 if (!ts->pending)
 500                         mod_timer(&ts->timer, jiffies);
 501
 502                 while (ts->pendown || ts->pending) {
 503                         spin_unlock_irqrestore(&ts->lock, flags);
 504                         msleep(1);
 505                         spin_lock_irqsave(&ts->lock, flags);
 506                 }
 507         }
 508
 509         /* we know the chip's in lowpower mode since we always
 510          * leave it that way after every request
 511          */
 512
 513         ts->disabled = 1;
 514 }
 515
 516 /* Must be called with ts->lock held */
 517 static void ads7846_enable(struct ads7846 *ts)
 518 {
 519         if (!ts->disabled)
 520                 return;
 521
 522         ts->disabled = 0;
 523         ts->irq_disabled = 0;
 524         enable_irq(ts->spi->irq);
 525 }
 526
 527 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 528 {
 529         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 530         unsigned long   flags;
 531
 532         spin_lock_irqsave(&ts->lock, flags);
 533
 534         spi->dev.power.power_state = message;
 535         ads7846_disable(ts);
 536
 537         spin_unlock_irqrestore(&ts->lock, flags);
 538
 539         return 0;
 540
 541 }
 542
 543 static int ads7846_resume(struct spi_device *spi)
 544 {
 545         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 546         unsigned long flags;
 547
 548         spin_lock_irqsave(&ts->lock, flags);
 549
 550         spi->dev.power.power_state = PMSG_ON;
 551         ads7846_enable(ts);
 552
 553         spin_unlock_irqrestore(&ts->lock, flags);
 554
 555         return 0;
 556 }
 557
 558 static int __devinit ads7846_probe(struct spi_device *spi)
 559 {
 560         struct ads7846                  *ts;
 561         struct input_dev                *input_dev;
 562         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 563         struct spi_message              *m;
 564         struct spi_transfer             *x;
 565         int                             err;
 566
 567         if (!spi->irq) {
 568                 dev_dbg(&spi->dev, "no IRQ?\n");
 569                 return -ENODEV;
 570         }
 571
 572         if (!pdata) {
 573                 dev_dbg(&spi->dev, "no platform data?\n");
 574                 return -ENODEV;
 575         }
 576
 577         /* don't exceed max specified sample rate */
 578         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 579                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 580                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 581                 return -EINVAL;
 582         }
 583
 584         /* We'd set the wordsize to 12 bits ... except that some controllers
 585          * will then treat the 8 bit command words as 12 bits (and drop the
 586          * four MSBs of the 12 bit result).  Result: inputs must be shifted
 587          * to discard the four garbage LSBs.
 588          */
 589
 590         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 591         input_dev = input_allocate_device();
 592         if (!ts || !input_dev) {
 593                 err = -ENOMEM;
 594                 goto err_free_mem;
 595         }
 596
 597         dev_set_drvdata(&spi->dev, ts);
 598         spi->dev.power.power_state = PMSG_ON;
 599
 600         ts->spi = spi;
 601         ts->input = input_dev;
 602
 603         init_timer(&ts->timer);
 604         ts->timer.data = (unsigned long) ts;
 605         ts->timer.function = ads7846_timer;
 606
 607         spin_lock_init(&ts->lock);
 608
 609         ts->model = pdata->model ? : 7846;
 610         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 611         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 612         ts->pressure_max = pdata->pressure_max ? : ~0;
 613         ts->debounce_max = pdata->debounce_max ? : 1;
 614         ts->debounce_tol = pdata->debounce_tol ? : 10;
 615
 616         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 617
 618         input_dev->name = "ADS784x Touchscreen";
 619         input_dev->phys = ts->phys;
 620         input_dev->cdev.dev = &spi->dev;
 621
 622         input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 623         input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 624         input_set_abs_params(input_dev, ABS_X,
 625                         pdata->x_min ? : 0,
 626                         pdata->x_max ? : MAX_12BIT,
 627                         0, 0);
 628         input_set_abs_params(input_dev, ABS_Y,
 629                         pdata->y_min ? : 0,
 630                         pdata->y_max ? : MAX_12BIT,
 631                         0, 0);
 632         input_set_abs_params(input_dev, ABS_PRESSURE,
 633                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 634
 635         /* set up the transfers to read touchscreen state; this assumes we
 636          * use formula #2 for pressure, not #3.
 637          */
 638         m = &ts->msg[0];
 639         x = ts->xfer;
 640
 641         spi_message_init(m);
 642
 643         /* y- still on; turn on only y+ (and ADC) */
 644         ts->read_y = READ_Y;
 645         x->tx_buf = &ts->read_y;
 646         x->len = 1;
 647         spi_message_add_tail(x, m);
 648
 649         x++;
 650         x->rx_buf = &ts->tc.y;
 651         x->len = 2;
 652         spi_message_add_tail(x, m);
 653
 654         m->complete = ads7846_debounce;
 655         m->context = ts;
 656
 657         m++;
 658         spi_message_init(m);
 659
 660         /* turn y- off, x+ on, then leave in lowpower */
 661         x++;
 662         ts->read_x = READ_X;
 663         x->tx_buf = &ts->read_x;
 664         x->len = 1;
 665         spi_message_add_tail(x, m);
 666
 667         x++;
 668         x->rx_buf = &ts->tc.x;
 669         x->len = 2;
 670         spi_message_add_tail(x, m);
 671
 672         m->complete = ads7846_debounce;
 673         m->context = ts;
 674
 675         /* turn y+ off, x- on; we'll use formula #2 */
 676         if (ts->model == 7846) {
 677                 m++;
 678                 spi_message_init(m);
 679
 680                 x++;
 681                 ts->read_z1 = READ_Z1;
 682                 x->tx_buf = &ts->read_z1;
 683                 x->len = 1;
 684                 spi_message_add_tail(x, m);
 685
 686                 x++;
 687                 x->rx_buf = &ts->tc.z1;
 688                 x->len = 2;
 689                 spi_message_add_tail(x, m);
 690
 691                 m->complete = ads7846_debounce;
 692                 m->context = ts;
 693
 694                 m++;
 695                 spi_message_init(m);
 696
 697                 x++;
 698                 ts->read_z2 = READ_Z2;
 699                 x->tx_buf = &ts->read_z2;
 700                 x->len = 1;
 701                 spi_message_add_tail(x, m);
 702
 703                 x++;
 704                 x->rx_buf = &ts->tc.z2;
 705                 x->len = 2;
 706                 spi_message_add_tail(x, m);
 707
 708                 m->complete = ads7846_debounce;
 709                 m->context = ts;
 710         }
 711
 712         /* power down */
 713         m++;
 714         spi_message_init(m);
 715
 716         x++;
 717         ts->pwrdown = PWRDOWN;
 718         x->tx_buf = &ts->pwrdown;
 719         x->len = 1;
 720         spi_message_add_tail(x, m);
 721
 722         x++;
 723         x->rx_buf = &ts->dummy;
 724         x->len = 2;
 725         CS_CHANGE(*x);
 726         spi_message_add_tail(x, m);
 727
 728         m->complete = ads7846_rx;
 729         m->context = ts;
 730
 731         if (request_irq(spi->irq, ads7846_irq,
 732                         SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING,
 733                         spi->dev.bus_id, ts)) {
 734                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
 735                 err = -EBUSY;
 736                 goto err_free_mem;
 737         }
 738
 739         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
 740
 741         /* take a first sample, leaving nPENIRQ active; avoid
 742          * the touchscreen, in case it's not connected.
 743          */
 744         (void) ads7846_read12_ser(&spi->dev,
 745                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
 746
 747         /* ads7843/7845 don't have temperature sensors, and
 748          * use the other sensors a bit differently too
 749          */
 750         if (ts->model == 7846) {
 751                 device_create_file(&spi->dev, &dev_attr_temp0);
 752                 device_create_file(&spi->dev, &dev_attr_temp1);
 753         }
 754         if (ts->model != 7845)
 755                 device_create_file(&spi->dev, &dev_attr_vbatt);
 756         device_create_file(&spi->dev, &dev_attr_vaux);
 757
 758         device_create_file(&spi->dev, &dev_attr_pen_down);
 759
 760         device_create_file(&spi->dev, &dev_attr_disable);
 761
 762         err = input_register_device(input_dev);
 763         if (err)
 764                 goto err_remove_attr;
 765
 766         return 0;
 767
 768  err_remove_attr:
 769         device_remove_file(&spi->dev, &dev_attr_disable);
 770         device_remove_file(&spi->dev, &dev_attr_pen_down);
 771         if (ts->model == 7846) {
 772                 device_remove_file(&spi->dev, &dev_attr_temp1);
 773                 device_remove_file(&spi->dev, &dev_attr_temp0);
 774         }
 775         if (ts->model != 7845)
 776                 device_remove_file(&spi->dev, &dev_attr_vbatt);
 777         device_remove_file(&spi->dev, &dev_attr_vaux);
 778
 779         free_irq(spi->irq, ts);
 780  err_free_mem:
 781         input_free_device(input_dev);
 782         kfree(ts);
 783         return err;
 784 }
 785
 786 static int __devexit ads7846_remove(struct spi_device *spi)
 787 {
 788         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
 789
 790         input_unregister_device(ts->input);
 791
 792         ads7846_suspend(spi, PMSG_SUSPEND);
 793
 794         device_remove_file(&spi->dev, &dev_attr_disable);
 795         device_remove_file(&spi->dev, &dev_attr_pen_down);
 796         if (ts->model == 7846) {
 797                 device_remove_file(&spi->dev, &dev_attr_temp1);
 798                 device_remove_file(&spi->dev, &dev_attr_temp0);
 799         }
 800         if (ts->model != 7845)
 801                 device_remove_file(&spi->dev, &dev_attr_vbatt);
 802         device_remove_file(&spi->dev, &dev_attr_vaux);
 803
 804         free_irq(ts->spi->irq, ts);
 805         if (ts->irq_disabled)
 806                 enable_irq(ts->spi->irq);
 807
 808         kfree(ts);
 809
 810         dev_dbg(&spi->dev, "unregistered touchscreen\n");
 811         return 0;
 812 }
 813
 814 static struct spi_driver ads7846_driver = {
 815         .driver = {
 816                 .name   = "ads7846",
 817                 .bus    = &spi_bus_type,
 818                 .owner  = THIS_MODULE,
 819         },
 820         .probe          = ads7846_probe,
 821         .remove         = __devexit_p(ads7846_remove),
 822         .suspend        = ads7846_suspend,
 823         .resume         = ads7846_resume,
 824 };
 825
 826 static int __init ads7846_init(void)
 827 {
 828         /* grr, board-specific init should stay out of drivers!! */
 829
 830 #ifdef  CONFIG_ARCH_OMAP
 831         if (machine_is_omap_osk()) {
 832                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
 833                 omap_request_gpio(4);
 834                 omap_set_gpio_direction(4, 1);
 835                 omap_request_gpio(6);
 836                 omap_set_gpio_direction(6, 1);
 837         }
 838         // also TI 1510 Innovator, bitbanging through FPGA
 839         // also Nokia 770
 840         // also Palm Tungsten T2
 841 #endif
 842
 843         // PXA:
 844         // also Dell Axim X50
 845         // also HP iPaq H191x/H192x/H415x/H435x
 846         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
 847         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
 848
 849         // Atmel at91sam9261-EK uses ads7843
 850
 851         // also various AMD Au1x00 devel boards
 852
 853         return spi_register_driver(&ads7846_driver);
 854 }
 855 module_init(ads7846_init);
 856
 857 static void __exit ads7846_exit(void)
 858 {
 859         spi_unregister_driver(&ads7846_driver);
 860
 861 #ifdef  CONFIG_ARCH_OMAP
 862         if (machine_is_omap_osk()) {
 863                 omap_free_gpio(4);
 864                 omap_free_gpio(6);
 865         }
 866 #endif
 867
 868 }
 869 module_exit(ads7846_exit);
 870
 871 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
 872 MODULE_LICENSE("GPL");