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