drivers/input/touchscreen/ads7846.c

   1 /*
   2  * ADS7846 based touchscreen and sensor driver
   3  *
   4  * Copyright (c) 2005 David Brownell
   5  *
   6  * Using code from:
   7  *  - corgi_ts.c
   8  *      Copyright (C) 2004-2005 Richard Purdie
   9  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  10  *      Copyright (C) 2002 MontaVista Software
  11  *      Copyright (C) 2004 Texas Instruments
  12  *      Copyright (C) 2005 Dirk Behme
  13  *
  14  *  This program is free software; you can redistribute it and/or modify
  15  *  it under the terms of the GNU General Public License version 2 as
  16  *  published by the Free Software Foundation.
  17  */
  18 #include <linux/device.h>
  19 #include <linux/init.h>
  20 #include <linux/delay.h>
  21 #include <linux/input.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/slab.h>
  24 #include <linux/spi/spi.h>
  25 #include <linux/spi/ads7846.h>
  26
  27 #ifdef  CONFIG_ARM
  28 #include <asm/mach-types.h>
  29 #ifdef  CONFIG_ARCH_OMAP
  30 #include <asm/arch/gpio.h>
  31 #endif
  32 #endif
  33
  34
  35 /*
  36  * This code has been lightly tested on an ads7846.
  37  * Support for ads7843 and ads7845 has only been stubbed in.
  38  *
  39  * Not yet done:  investigate the values reported.  Are x/y/pressure
  40  * event values sane enough for X11?  How accurate are the temperature
  41  * and voltage readings?  (System-specific calibration should support
  42  * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.)
  43  *
  44  * app note sbaa036 talks in more detail about accurate sampling...
  45  * that ought to help in situations like LCDs inducing noise (which
  46  * can also be helped by using synch signals) and more generally.
  47  */
  48
  49 #define TS_POLL_PERIOD  msecs_to_jiffies(10)
  50
  51 /* this driver doesn't aim at the peak continuous sample rate */
  52 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  53
  54 struct ts_event {
  55         /* For portability, we can't read 12 bit values using SPI (which
  56          * would make the controller deliver them as native byteorder u16
  57          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  58          * which need byteswapping then range adjustment.
  59          */
  60         __be16 x;
  61         __be16 y;
  62         __be16 z1, z2;
  63 };
  64
  65 struct ads7846 {
  66         struct input_dev        *input;
  67         char                    phys[32];
  68
  69         struct spi_device       *spi;
  70         u16                     model;
  71         u16                     vref_delay_usecs;
  72         u16                     x_plate_ohms;
  73
  74         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  75         u16                     dummy;          /* for the pwrdown read */
  76         struct ts_event         tc;
  77
  78         struct spi_transfer     xfer[10];
  79         struct spi_message      msg;
  80
  81         spinlock_t              lock;
  82         struct timer_list       timer;          /* P: lock */
  83         unsigned                pendown:1;      /* P: lock */
  84         unsigned                pending:1;      /* P: lock */
  85 // FIXME remove "irq_disabled"
  86         unsigned                irq_disabled:1; /* P: lock */
  87 };
  88
  89 /* leave chip selected when we're done, for quicker re-select? */
  90 #if     0
  91 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
  92 #else
  93 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
  94 #endif
  95
  96 /*--------------------------------------------------------------------------*/
  97
  98 /* The ADS7846 has touchscreen and other sensors.
  99  * Earlier ads784x chips are somewhat compatible.
 100  */
 101 #define ADS_START               (1 << 7)
 102 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 103 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 104 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 105 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 106 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 107 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 108 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 109 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 110 #define ADS_8_BIT               (1 << 3)
 111 #define ADS_12_BIT              (0 << 3)
 112 #define ADS_SER                 (1 << 2)        /* non-differential */
 113 #define ADS_DFR                 (0 << 2)        /* differential */
 114 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 115 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 116 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 117 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 118
 119 #define MAX_12BIT       ((1<<12)-1)
 120
 121 /* leave ADC powered up (disables penirq) between differential samples */
 122 #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
 123         | ADS_12_BIT | ADS_DFR)
 124
 125 #define READ_Y  (READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON)
 126 #define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
 127 #define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
 128
 129 #define READ_X  (READ_12BIT_DFR(x)  | ADS_PD10_ADC_ON)
 130 #define PWRDOWN (READ_12BIT_DFR(y)  | ADS_PD10_PDOWN)   /* LAST */
 131
 132 /* single-ended samples need to first power up reference voltage;
 133  * we leave both ADC and VREF powered
 134  */
 135 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 136         | ADS_12_BIT | ADS_SER)
 137
 138 #define REF_ON  (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
 139 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
 140
 141 /*--------------------------------------------------------------------------*/
 142
 143 /*
 144  * Non-touchscreen sensors only use single-ended conversions.
 145  */
 146
 147 struct ser_req {
 148         u8                      ref_on;
 149         u8                      command;
 150         u8                      ref_off;
 151         u16                     scratch;
 152         __be16                  sample;
 153         struct spi_message      msg;
 154         struct spi_transfer     xfer[6];
 155 };
 156
 157 static int ads7846_read12_ser(struct device *dev, unsigned command)
 158 {
 159         struct spi_device       *spi = to_spi_device(dev);
 160         struct ads7846          *ts = dev_get_drvdata(dev);
 161         struct ser_req          *req = kzalloc(sizeof *req, SLAB_KERNEL);
 162         int                     status;
 163         int                     sample;
 164         int                     i;
 165
 166         if (!req)
 167                 return -ENOMEM;
 168
 169         spi_message_init(&req->msg);
 170
 171         /* activate reference, so it has time to settle; */
 172         req->ref_on = REF_ON;
 173         req->xfer[0].tx_buf = &req->ref_on;
 174         req->xfer[0].len = 1;
 175         req->xfer[1].rx_buf = &req->scratch;
 176         req->xfer[1].len = 2;
 177
 178         /*
 179          * for external VREF, 0 usec (and assume it's always on);
 180          * for 1uF, use 800 usec;
 181          * no cap, 100 usec.
 182          */
 183         req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 184
 185         /* take sample */
 186         req->command = (u8) command;
 187         req->xfer[2].tx_buf = &req->command;
 188         req->xfer[2].len = 1;
 189         req->xfer[3].rx_buf = &req->sample;
 190         req->xfer[3].len = 2;
 191
 192         /* REVISIT:  take a few more samples, and compare ... */
 193
 194         /* turn off reference */
 195         req->ref_off = REF_OFF;
 196         req->xfer[4].tx_buf = &req->ref_off;
 197         req->xfer[4].len = 1;
 198         req->xfer[5].rx_buf = &req->scratch;
 199         req->xfer[5].len = 2;
 200
 201         CS_CHANGE(req->xfer[5]);
 202
 203         /* group all the transfers together, so we can't interfere with
 204          * reading touchscreen state; disable penirq while sampling
 205          */
 206         for (i = 0; i < 6; i++)
 207                 spi_message_add_tail(&req->xfer[i], &req->msg);
 208
 209         disable_irq(spi->irq);
 210         status = spi_sync(spi, &req->msg);
 211         enable_irq(spi->irq);
 212
 213         if (req->msg.status)
 214                 status = req->msg.status;
 215         sample = be16_to_cpu(req->sample);
 216         sample = sample >> 4;
 217         kfree(req);
 218
 219         return status ? status : sample;
 220 }
 221
 222 #define SHOW(name) static ssize_t \
 223 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 224 { \
 225         ssize_t v = ads7846_read12_ser(dev, \
 226                         READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
 227         if (v < 0) \
 228                 return v; \
 229         return sprintf(buf, "%u\n", (unsigned) v); \
 230 } \
 231 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 232
 233 SHOW(temp0)
 234 SHOW(temp1)
 235 SHOW(vaux)
 236 SHOW(vbatt)
 237
 238 /*--------------------------------------------------------------------------*/
 239
 240 /*
 241  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 242  * to retrieve touchscreen status.
 243  *
 244  * The SPI transfer completion callback does the real work.  It reports
 245  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 246  */
 247
 248 static void ads7846_rx(void *ads)
 249 {
 250         struct ads7846          *ts = ads;
 251         struct input_dev        *input_dev = ts->input;
 252         unsigned                Rt;
 253         unsigned                sync = 0;
 254         u16                     x, y, z1, z2;
 255         unsigned long           flags;
 256
 257         /* adjust:  12 bit samples (left aligned), built from
 258          * two 8 bit values writen msb-first.
 259          */
 260         x = ts->tc.x >> 3;
 261         y = ts->tc.y >> 3;
 262         z1 = ts->tc.z1 >> 3;
 263         z2 = ts->tc.z2 >> 3;
 264
 265         /* range filtering */
 266         if (x == MAX_12BIT)
 267                 x = 0;
 268
 269         if (x && z1 && ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
 270                 /* compute touch pressure resistance using equation #2 */
 271                 Rt = z2;
 272                 Rt -= z1;
 273                 Rt *= x;
 274                 Rt *= ts->x_plate_ohms;
 275                 Rt /= z1;
 276                 Rt = (Rt + 2047) >> 12;
 277         } else
 278                 Rt = 0;
 279
 280         /* NOTE:  "pendown" is inferred from pressure; we don't rely on
 281          * being able to check nPENIRQ status, or "friendly" trigger modes
 282          * (both-edges is much better than just-falling or low-level).
 283          *
 284          * REVISIT:  some boards may require reading nPENIRQ; it's
 285          * needed on 7843.  and 7845 reads pressure differently...
 286          *
 287          * REVISIT:  the touchscreen might not be connected; this code
 288          * won't notice that, even if nPENIRQ never fires ...
 289          */
 290         if (!ts->pendown && Rt != 0) {
 291                 input_report_key(input_dev, BTN_TOUCH, 1);
 292                 sync = 1;
 293         } else if (ts->pendown && Rt == 0) {
 294                 input_report_key(input_dev, BTN_TOUCH, 0);
 295                 sync = 1;
 296         }
 297
 298         if (Rt) {
 299                 input_report_abs(input_dev, ABS_X, x);
 300                 input_report_abs(input_dev, ABS_Y, y);
 301                 input_report_abs(input_dev, ABS_PRESSURE, Rt);
 302                 sync = 1;
 303         }
 304         if (sync)
 305                 input_sync(input_dev);
 306
 307 #ifdef  VERBOSE
 308         if (Rt || ts->pendown)
 309                 pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
 310                         x, y, Rt, Rt ? "" : " UP");
 311 #endif
 312
 313         /* don't retrigger while we're suspended */
 314         spin_lock_irqsave(&ts->lock, flags);
 315
 316         ts->pendown = (Rt != 0);
 317         ts->pending = 0;
 318
 319         if (ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
 320                 if (ts->pendown)
 321                         mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
 322                 else if (ts->irq_disabled) {
 323                         ts->irq_disabled = 0;
 324                         enable_irq(ts->spi->irq);
 325                 }
 326         }
 327
 328         spin_unlock_irqrestore(&ts->lock, flags);
 329 }
 330
 331 static void ads7846_timer(unsigned long handle)
 332 {
 333         struct ads7846  *ts = (void *)handle;
 334         int             status = 0;
 335         unsigned long   flags;
 336
 337         spin_lock_irqsave(&ts->lock, flags);
 338         if (!ts->pending) {
 339                 ts->pending = 1;
 340                 if (!ts->irq_disabled) {
 341                         ts->irq_disabled = 1;
 342                         disable_irq(ts->spi->irq);
 343                 }
 344                 status = spi_async(ts->spi, &ts->msg);
 345                 if (status)
 346                         dev_err(&ts->spi->dev, "spi_async --> %d\n",
 347                                         status);
 348         }
 349         spin_unlock_irqrestore(&ts->lock, flags);
 350 }
 351
 352 static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
 353 {
 354         ads7846_timer((unsigned long) handle);
 355         return IRQ_HANDLED;
 356 }
 357
 358 /*--------------------------------------------------------------------------*/
 359
 360 static int
 361 ads7846_suspend(struct spi_device *spi, pm_message_t message)
 362 {
 363         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 364         unsigned long   flags;
 365
 366         spin_lock_irqsave(&ts->lock, flags);
 367
 368         spi->dev.power.power_state = message;
 369
 370         /* are we waiting for IRQ, or polling? */
 371         if (!ts->pendown) {
 372                 if (!ts->irq_disabled) {
 373                         ts->irq_disabled = 1;
 374                         disable_irq(ts->spi->irq);
 375                 }
 376         } else {
 377                 /* polling; force a final SPI completion;
 378                  * that will clean things up neatly
 379                  */
 380                 if (!ts->pending)
 381                         mod_timer(&ts->timer, jiffies);
 382
 383                 while (ts->pendown || ts->pending) {
 384                         spin_unlock_irqrestore(&ts->lock, flags);
 385                         udelay(10);
 386                         spin_lock_irqsave(&ts->lock, flags);
 387                 }
 388         }
 389
 390         /* we know the chip's in lowpower mode since we always
 391          * leave it that way after every request
 392          */
 393
 394         spin_unlock_irqrestore(&ts->lock, flags);
 395         return 0;
 396 }
 397
 398 static int ads7846_resume(struct spi_device *spi)
 399 {
 400         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 401
 402         ts->irq_disabled = 0;
 403         enable_irq(ts->spi->irq);
 404         spi->dev.power.power_state = PMSG_ON;
 405         return 0;
 406 }
 407
 408 static int __devinit ads7846_probe(struct spi_device *spi)
 409 {
 410         struct ads7846                  *ts;
 411         struct input_dev                *input_dev;
 412         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 413         struct spi_transfer             *x;
 414         int                             err;
 415
 416         if (!spi->irq) {
 417                 dev_dbg(&spi->dev, "no IRQ?\n");
 418                 return -ENODEV;
 419         }
 420
 421         if (!pdata) {
 422                 dev_dbg(&spi->dev, "no platform data?\n");
 423                 return -ENODEV;
 424         }
 425
 426         /* don't exceed max specified sample rate */
 427         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 428                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 429                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 430                 return -EINVAL;
 431         }
 432
 433         /* We'd set the wordsize to 12 bits ... except that some controllers
 434          * will then treat the 8 bit command words as 12 bits (and drop the
 435          * four MSBs of the 12 bit result).  Result: inputs must be shifted
 436          * to discard the four garbage LSBs.
 437          */
 438
 439         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 440         input_dev = input_allocate_device();
 441         if (!ts || !input_dev) {
 442                 err = -ENOMEM;
 443                 goto err_free_mem;
 444         }
 445
 446         dev_set_drvdata(&spi->dev, ts);
 447         spi->dev.power.power_state = PMSG_ON;
 448
 449         ts->spi = spi;
 450         ts->input = input_dev;
 451
 452         init_timer(&ts->timer);
 453         ts->timer.data = (unsigned long) ts;
 454         ts->timer.function = ads7846_timer;
 455
 456         ts->model = pdata->model ? : 7846;
 457         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 458         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 459
 460         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 461
 462         input_dev->name = "ADS784x Touchscreen";
 463         input_dev->phys = ts->phys;
 464         input_dev->cdev.dev = &spi->dev;
 465
 466         input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 467         input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 468         input_set_abs_params(input_dev, ABS_X,
 469                         pdata->x_min ? : 0,
 470                         pdata->x_max ? : MAX_12BIT,
 471                         0, 0);
 472         input_set_abs_params(input_dev, ABS_Y,
 473                         pdata->y_min ? : 0,
 474                         pdata->y_max ? : MAX_12BIT,
 475                         0, 0);
 476         input_set_abs_params(input_dev, ABS_PRESSURE,
 477                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 478
 479         /* set up the transfers to read touchscreen state; this assumes we
 480          * use formula #2 for pressure, not #3.
 481          */
 482         spi_message_init(&ts->msg);
 483         x = ts->xfer;
 484
 485         /* y- still on; turn on only y+ (and ADC) */
 486         ts->read_y = READ_Y;
 487         x->tx_buf = &ts->read_y;
 488         x->len = 1;
 489         spi_message_add_tail(x, &ts->msg);
 490
 491         x++;
 492         x->rx_buf = &ts->tc.y;
 493         x->len = 2;
 494         spi_message_add_tail(x, &ts->msg);
 495
 496         /* turn y+ off, x- on; we'll use formula #2 */
 497         if (ts->model == 7846) {
 498                 x++;
 499                 ts->read_z1 = READ_Z1;
 500                 x->tx_buf = &ts->read_z1;
 501                 x->len = 1;
 502                 spi_message_add_tail(x, &ts->msg);
 503
 504                 x++;
 505                 x->rx_buf = &ts->tc.z1;
 506                 x->len = 2;
 507                 spi_message_add_tail(x, &ts->msg);
 508
 509                 x++;
 510                 ts->read_z2 = READ_Z2;
 511                 x->tx_buf = &ts->read_z2;
 512                 x->len = 1;
 513                 spi_message_add_tail(x, &ts->msg);
 514
 515                 x++;
 516                 x->rx_buf = &ts->tc.z2;
 517                 x->len = 2;
 518                 spi_message_add_tail(x, &ts->msg);
 519         }
 520
 521         /* turn y- off, x+ on, then leave in lowpower */
 522         x++;
 523         ts->read_x = READ_X;
 524         x->tx_buf = &ts->read_x;
 525         x->len = 1;
 526         spi_message_add_tail(x, &ts->msg);
 527
 528         x++;
 529         x->rx_buf = &ts->tc.x;
 530         x->len = 2;
 531         spi_message_add_tail(x, &ts->msg);
 532
 533         /* power down */
 534         x++;
 535         ts->pwrdown = PWRDOWN;
 536         x->tx_buf = &ts->pwrdown;
 537         x->len = 1;
 538         spi_message_add_tail(x, &ts->msg);
 539
 540         x++;
 541         x->rx_buf = &ts->dummy;
 542         x->len = 2;
 543         CS_CHANGE(*x);
 544         spi_message_add_tail(x, &ts->msg);
 545
 546         ts->msg.complete = ads7846_rx;
 547         ts->msg.context = ts;
 548
 549         if (request_irq(spi->irq, ads7846_irq,
 550                         SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING,
 551                         spi->dev.bus_id, ts)) {
 552                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
 553                 err = -EBUSY;
 554                 goto err_free_mem;
 555         }
 556
 557         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
 558
 559         /* take a first sample, leaving nPENIRQ active; avoid
 560          * the touchscreen, in case it's not connected.
 561          */
 562         (void) ads7846_read12_ser(&spi->dev,
 563                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
 564
 565         /* ads7843/7845 don't have temperature sensors, and
 566          * use the other sensors a bit differently too
 567          */
 568         if (ts->model == 7846) {
 569                 device_create_file(&spi->dev, &dev_attr_temp0);
 570                 device_create_file(&spi->dev, &dev_attr_temp1);
 571         }
 572         if (ts->model != 7845)
 573                 device_create_file(&spi->dev, &dev_attr_vbatt);
 574         device_create_file(&spi->dev, &dev_attr_vaux);
 575
 576         err = input_register_device(input_dev);
 577         if (err)
 578                 goto err_free_irq;
 579
 580         return 0;
 581
 582  err_free_irq:
 583         free_irq(spi->irq, ts);
 584  err_free_mem:
 585         input_free_device(input_dev);
 586         kfree(ts);
 587         return err;
 588 }
 589
 590 static int __devexit ads7846_remove(struct spi_device *spi)
 591 {
 592         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
 593
 594         ads7846_suspend(spi, PMSG_SUSPEND);
 595         free_irq(ts->spi->irq, ts);
 596         if (ts->irq_disabled)
 597                 enable_irq(ts->spi->irq);
 598
 599         if (ts->model == 7846) {
 600                 device_remove_file(&spi->dev, &dev_attr_temp0);
 601                 device_remove_file(&spi->dev, &dev_attr_temp1);
 602         }
 603         if (ts->model != 7845)
 604                 device_remove_file(&spi->dev, &dev_attr_vbatt);
 605         device_remove_file(&spi->dev, &dev_attr_vaux);
 606
 607         input_unregister_device(ts->input);
 608         kfree(ts);
 609
 610         dev_dbg(&spi->dev, "unregistered touchscreen\n");
 611         return 0;
 612 }
 613
 614 static struct spi_driver ads7846_driver = {
 615         .driver = {
 616                 .name   = "ads7846",
 617                 .bus    = &spi_bus_type,
 618                 .owner  = THIS_MODULE,
 619         },
 620         .probe          = ads7846_probe,
 621         .remove         = __devexit_p(ads7846_remove),
 622         .suspend        = ads7846_suspend,
 623         .resume         = ads7846_resume,
 624 };
 625
 626 static int __init ads7846_init(void)
 627 {
 628         /* grr, board-specific init should stay out of drivers!! */
 629
 630 #ifdef  CONFIG_ARCH_OMAP
 631         if (machine_is_omap_osk()) {
 632                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
 633                 omap_request_gpio(4);
 634                 omap_set_gpio_direction(4, 1);
 635                 omap_request_gpio(6);
 636                 omap_set_gpio_direction(6, 1);
 637         }
 638         // also TI 1510 Innovator, bitbanging through FPGA
 639         // also Nokia 770
 640         // also Palm Tungsten T2
 641 #endif
 642
 643         // PXA:
 644         // also Dell Axim X50
 645         // also HP iPaq H191x/H192x/H415x/H435x
 646         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
 647         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
 648
 649         // Atmel at91sam9261-EK uses ads7843
 650
 651         // also various AMD Au1x00 devel boards
 652
 653         return spi_register_driver(&ads7846_driver);
 654 }
 655 module_init(ads7846_init);
 656
 657 static void __exit ads7846_exit(void)
 658 {
 659         spi_unregister_driver(&ads7846_driver);
 660
 661 #ifdef  CONFIG_ARCH_OMAP
 662         if (machine_is_omap_osk()) {
 663                 omap_free_gpio(4);
 664                 omap_free_gpio(6);
 665         }
 666 #endif
 667
 668 }
 669 module_exit(ads7846_exit);
 670
 671 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
 672 MODULE_LICENSE("GPL");