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