drivers/input/touchscreen/intel-mid-touch.c

   1 /*
   2  * Intel MID Resistive Touch Screen Driver
   3  *
   4  * Copyright (C) 2008 Intel Corp
   5  *
   6  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; version 2 of the License.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, write to the Free Software Foundation, Inc.,
  19  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  20  *
  21  * Questions/Comments/Bug fixes to Sreedhara (sreedhara.ds@intel.com)
  22  *                          Ramesh Agarwal (ramesh.agarwal@intel.com)
  23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24  *
  25  * TODO:
  26  *      review conversion of r/m/w sequences
  27  */
  28
  29 #include <linux/module.h>
  30 #include <linux/init.h>
  31 #include <linux/input.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/err.h>
  34 #include <linux/param.h>
  35 #include <linux/slab.h>
  36 #include <linux/platform_device.h>
  37 #include <linux/irq.h>
  38 #include <linux/delay.h>
  39 #include <asm/intel_scu_ipc.h>
  40
  41 /* PMIC Interrupt registers */
  42 #define PMIC_REG_ID1            0x00 /* PMIC ID1 register */
  43
  44 /* PMIC Interrupt registers */
  45 #define PMIC_REG_INT            0x04 /* PMIC interrupt register */
  46 #define PMIC_REG_MINT           0x05 /* PMIC interrupt mask register */
  47
  48 /* ADC Interrupt registers */
  49 #define PMIC_REG_ADCINT         0x5F /* ADC interrupt register */
  50 #define PMIC_REG_MADCINT        0x60 /* ADC interrupt mask register */
  51
  52 /* ADC Control registers */
  53 #define PMIC_REG_ADCCNTL1       0x61 /* ADC control register */
  54
  55 /* ADC Channel Selection registers */
  56 #define PMICADDR0               0xA4
  57 #define END_OF_CHANNEL          0x1F
  58
  59 /* ADC Result register */
  60 #define PMIC_REG_ADCSNS0H       0x64
  61
  62 /* ADC channels for touch screen */
  63 #define MRST_TS_CHAN10          0xA /* Touch screen X+ connection */
  64 #define MRST_TS_CHAN11          0xB /* Touch screen X- connection */
  65 #define MRST_TS_CHAN12          0xC /* Touch screen Y+ connection */
  66 #define MRST_TS_CHAN13          0xD /* Touch screen Y- connection */
  67
  68 /* Touch screen channel BIAS constants */
  69 #define MRST_XBIAS              0x20
  70 #define MRST_YBIAS              0x40
  71 #define MRST_ZBIAS              0x80
  72
  73 /* Touch screen coordinates */
  74 #define MRST_X_MIN              10
  75 #define MRST_X_MAX              1024
  76 #define MRST_X_FUZZ             5
  77 #define MRST_Y_MIN              10
  78 #define MRST_Y_MAX              1024
  79 #define MRST_Y_FUZZ             5
  80 #define MRST_PRESSURE_MIN       0
  81 #define MRST_PRESSURE_NOMINAL   50
  82 #define MRST_PRESSURE_MAX       100
  83
  84 #define WAIT_ADC_COMPLETION     10 /* msec */
  85
  86 /* PMIC ADC round robin delays */
  87 #define ADC_LOOP_DELAY0         0x0 /* Continuous loop */
  88 #define ADC_LOOP_DELAY1         0x1 /* 4.5  ms approximate */
  89
  90 /* PMIC Vendor Identifiers */
  91 #define PMIC_VENDOR_FS          0 /* PMIC vendor FreeScale */
  92 #define PMIC_VENDOR_MAXIM       1 /* PMIC vendor MAXIM */
  93 #define PMIC_VENDOR_NEC         2 /* PMIC vendor NEC */
  94 #define MRSTOUCH_MAX_CHANNELS   32 /* Maximum ADC channels */
  95
  96 /* Touch screen device structure */
  97 struct mrstouch_dev {
  98         struct device *dev; /* device associated with touch screen */
  99         struct input_dev *input;
 100         char phys[32];
 101         u16 asr;                /* Address selection register */
 102         int irq;
 103         unsigned int vendor;    /* PMIC vendor */
 104         unsigned int rev;       /* PMIC revision */
 105
 106         int (*read_prepare)(struct mrstouch_dev *tsdev);
 107         int (*read)(struct mrstouch_dev *tsdev, u16 *x, u16 *y, u16 *z);
 108         int (*read_finish)(struct mrstouch_dev *tsdev);
 109 };
 110
 111
 112 /*************************** NEC and Maxim Interface ************************/
 113
 114 static int mrstouch_nec_adc_read_prepare(struct mrstouch_dev *tsdev)
 115 {
 116         return intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0, 0x20);
 117 }
 118
 119 /*
 120  * Enables PENDET interrupt.
 121  */
 122 static int mrstouch_nec_adc_read_finish(struct mrstouch_dev *tsdev)
 123 {
 124         int err;
 125
 126         err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x20, 0x20);
 127         if (!err)
 128                 err = intel_scu_ipc_update_register(PMIC_REG_ADCCNTL1, 0, 0x05);
 129
 130         return err;
 131 }
 132
 133 /*
 134  * Reads PMIC ADC touch screen result
 135  * Reads ADC storage registers for higher 7 and lower 3 bits and
 136  * converts the two readings into a single value and turns off gain bit
 137  */
 138 static int mrstouch_ts_chan_read(u16 offset, u16 chan, u16 *vp, u16 *vm)
 139 {
 140         int err;
 141         u16 result;
 142         u32 res;
 143
 144         result = PMIC_REG_ADCSNS0H + offset;
 145
 146         if (chan == MRST_TS_CHAN12)
 147                 result += 4;
 148
 149         err = intel_scu_ipc_ioread32(result, &res);
 150         if (err)
 151                 return err;
 152
 153         /* Mash the bits up */
 154
 155         *vp = (res & 0xFF) << 3;        /* Highest 7 bits */
 156         *vp |= (res >> 8) & 0x07;       /* Lower 3 bits */
 157         *vp &= 0x3FF;
 158
 159         res >>= 16;
 160
 161         *vm = (res & 0xFF) << 3;        /* Highest 7 bits */
 162         *vm |= (res >> 8) & 0x07;       /* Lower 3 bits */
 163         *vm &= 0x3FF;
 164
 165         return 0;
 166 }
 167
 168 /*
 169  * Enables X, Y and Z bias values
 170  * Enables YPYM for X channels and XPXM for Y channels
 171  */
 172 static int mrstouch_ts_bias_set(uint offset, uint bias)
 173 {
 174         int count;
 175         u16 chan, start;
 176         u16 reg[4];
 177         u8 data[4];
 178
 179         chan = PMICADDR0 + offset;
 180         start = MRST_TS_CHAN10;
 181
 182         for (count = 0; count <= 3; count++) {
 183                 reg[count] = chan++;
 184                 data[count] = bias | (start + count);
 185         }
 186
 187         return intel_scu_ipc_writev(reg, data, 4);
 188 }
 189
 190 /* To read touch screen channel values */
 191 static int mrstouch_nec_adc_read(struct mrstouch_dev *tsdev,
 192                                  u16 *x, u16 *y, u16 *z)
 193 {
 194         int err;
 195         u16 xm, ym, zm;
 196
 197         /* configure Y bias for X channels */
 198         err = mrstouch_ts_bias_set(tsdev->asr, MRST_YBIAS);
 199         if (err)
 200                 goto ipc_error;
 201
 202         msleep(WAIT_ADC_COMPLETION);
 203
 204         /* read x+ and x- channels */
 205         err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN10, x, &xm);
 206         if (err)
 207                 goto ipc_error;
 208
 209         /* configure x bias for y channels */
 210         err = mrstouch_ts_bias_set(tsdev->asr, MRST_XBIAS);
 211         if (err)
 212                 goto ipc_error;
 213
 214         msleep(WAIT_ADC_COMPLETION);
 215
 216         /* read y+ and y- channels */
 217         err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN12, y, &ym);
 218         if (err)
 219                 goto ipc_error;
 220
 221         /* configure z bias for x and y channels */
 222         err = mrstouch_ts_bias_set(tsdev->asr, MRST_ZBIAS);
 223         if (err)
 224                 goto ipc_error;
 225
 226         msleep(WAIT_ADC_COMPLETION);
 227
 228         /* read z+ and z- channels */
 229         err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN10, z, &zm);
 230         if (err)
 231                 goto ipc_error;
 232
 233         return 0;
 234
 235 ipc_error:
 236         dev_err(tsdev->dev, "ipc error during adc read\n");
 237         return err;
 238 }
 239
 240
 241 /*************************** Freescale Interface ************************/
 242
 243 static int mrstouch_fs_adc_read_prepare(struct mrstouch_dev *tsdev)
 244 {
 245         int err, count;
 246         u16 chan;
 247         u16 reg[5];
 248         u8 data[5];
 249
 250         /* Stop the ADC */
 251         err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x00, 0x02);
 252         if (err)
 253                 goto ipc_error;
 254
 255         chan = PMICADDR0 + tsdev->asr;
 256
 257         /* Set X BIAS */
 258         for (count = 0; count <= 3; count++) {
 259                 reg[count] = chan++;
 260                 data[count] = 0x2A;
 261         }
 262         reg[count] =  chan++; /* Dummy */
 263         data[count] = 0;
 264
 265         err = intel_scu_ipc_writev(reg, data, 5);
 266         if (err)
 267                 goto ipc_error;
 268
 269         msleep(WAIT_ADC_COMPLETION);
 270
 271         /* Set Y BIAS */
 272         for (count = 0; count <= 3; count++) {
 273                 reg[count] = chan++;
 274                 data[count] = 0x4A;
 275         }
 276         reg[count] = chan++; /* Dummy */
 277         data[count] = 0;
 278
 279         err = intel_scu_ipc_writev(reg, data, 5);
 280         if (err)
 281                 goto ipc_error;
 282
 283         msleep(WAIT_ADC_COMPLETION);
 284
 285         /* Set Z BIAS */
 286         err = intel_scu_ipc_iowrite32(chan + 2, 0x8A8A8A8A);
 287         if (err)
 288                 goto ipc_error;
 289
 290         msleep(WAIT_ADC_COMPLETION);
 291
 292         return 0;
 293
 294 ipc_error:
 295         dev_err(tsdev->dev, "ipc error during %s\n", __func__);
 296         return err;
 297 }
 298
 299 static int mrstouch_fs_adc_read(struct mrstouch_dev *tsdev,
 300                                 u16 *x, u16 *y, u16 *z)
 301 {
 302         int err;
 303         u16 result;
 304         u16 reg[4];
 305         u8 data[4];
 306
 307         result = PMIC_REG_ADCSNS0H + tsdev->asr;
 308
 309         reg[0] = result + 4;
 310         reg[1] = result + 5;
 311         reg[2] = result + 16;
 312         reg[3] = result + 17;
 313
 314         err = intel_scu_ipc_readv(reg, data, 4);
 315         if (err)
 316                 goto ipc_error;
 317
 318         *x = data[0] << 3; /* Higher 7 bits */
 319         *x |= data[1] & 0x7; /* Lower 3 bits */
 320         *x &= 0x3FF;
 321
 322         *y = data[2] << 3; /* Higher 7 bits */
 323         *y |= data[3] & 0x7; /* Lower 3 bits */
 324         *y &= 0x3FF;
 325
 326         /* Read Z value */
 327         reg[0] = result + 28;
 328         reg[1] = result + 29;
 329
 330         err = intel_scu_ipc_readv(reg, data, 4);
 331         if (err)
 332                 goto ipc_error;
 333
 334         *z = data[0] << 3; /* Higher 7 bits */
 335         *z |= data[1] & 0x7; /* Lower 3 bits */
 336         *z &= 0x3FF;
 337
 338         return 0;
 339
 340 ipc_error:
 341         dev_err(tsdev->dev, "ipc error during %s\n", __func__);
 342         return err;
 343 }
 344
 345 static int mrstouch_fs_adc_read_finish(struct mrstouch_dev *tsdev)
 346 {
 347         int err, count;
 348         u16 chan;
 349         u16 reg[5];
 350         u8 data[5];
 351
 352         /* Clear all TS channels */
 353         chan = PMICADDR0 + tsdev->asr;
 354         for (count = 0; count <= 4; count++) {
 355                 reg[count] = chan++;
 356                 data[count] = 0;
 357         }
 358         err = intel_scu_ipc_writev(reg, data, 5);
 359         if (err)
 360                 goto ipc_error;
 361
 362         for (count = 0; count <= 4; count++) {
 363                 reg[count] = chan++;
 364                 data[count] = 0;
 365         }
 366         err = intel_scu_ipc_writev(reg, data, 5);
 367         if (err)
 368                 goto ipc_error;
 369
 370         err = intel_scu_ipc_iowrite32(chan + 2, 0x00000000);
 371         if (err)
 372                 goto ipc_error;
 373
 374         /* Start ADC */
 375         err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x02, 0x02);
 376         if (err)
 377                 goto ipc_error;
 378
 379         return 0;
 380
 381 ipc_error:
 382         dev_err(tsdev->dev, "ipc error during %s\n", __func__);
 383         return err;
 384 }
 385
 386 static void mrstouch_report_event(struct input_dev *input,
 387                         unsigned int x, unsigned int y, unsigned int z)
 388 {
 389         if (z > MRST_PRESSURE_NOMINAL) {
 390                 /* Pen touched, report button touch and coordinates */
 391                 input_report_key(input, BTN_TOUCH, 1);
 392                 input_report_abs(input, ABS_X, x);
 393                 input_report_abs(input, ABS_Y, y);
 394         } else {
 395                 input_report_key(input, BTN_TOUCH, 0);
 396         }
 397
 398         input_report_abs(input, ABS_PRESSURE, z);
 399         input_sync(input);
 400 }
 401
 402 /* PENDET interrupt handler */
 403 static irqreturn_t mrstouch_pendet_irq(int irq, void *dev_id)
 404 {
 405         struct mrstouch_dev *tsdev = dev_id;
 406         u16 x, y, z;
 407
 408         /*
 409          * Should we lower thread priority? Probably not, since we are
 410          * not spinning but sleeping...
 411          */
 412
 413         if (tsdev->read_prepare(tsdev))
 414                 goto out;
 415
 416         do {
 417                 if (tsdev->read(tsdev, &x, &y, &z))
 418                         break;
 419
 420                 mrstouch_report_event(tsdev->input, x, y, z);
 421         } while (z > MRST_PRESSURE_NOMINAL);
 422
 423         tsdev->read_finish(tsdev);
 424
 425 out:
 426         return IRQ_HANDLED;
 427 }
 428
 429 /* Utility to read PMIC ID */
 430 static int __devinit mrstouch_read_pmic_id(uint *vendor, uint *rev)
 431 {
 432         int err;
 433         u8 r;
 434
 435         err = intel_scu_ipc_ioread8(PMIC_REG_ID1, &r);
 436         if (err)
 437                 return err;
 438
 439         *vendor = r & 0x7;
 440         *rev = (r >> 3) & 0x7;
 441
 442         return 0;
 443 }
 444
 445 /*
 446  * Parse ADC channels to find end of the channel configured by other ADC user
 447  * NEC and MAXIM requires 4 channels and FreeScale needs 18 channels
 448  */
 449 static int __devinit mrstouch_chan_parse(struct mrstouch_dev *tsdev)
 450 {
 451         int err, i, found;
 452         u8 r8;
 453
 454         found = -1;
 455
 456         for (i = 0; i < MRSTOUCH_MAX_CHANNELS; i++) {
 457                 if (found >= 0)
 458                         break;
 459
 460                 err = intel_scu_ipc_ioread8(PMICADDR0 + i, &r8);
 461                 if (err)
 462                         return err;
 463
 464                 if (r8 == END_OF_CHANNEL) {
 465                         found = i;
 466                         break;
 467                 }
 468         }
 469         if (found < 0)
 470                 return 0;
 471
 472         if (tsdev->vendor == PMIC_VENDOR_FS) {
 473                 if (found && found > (MRSTOUCH_MAX_CHANNELS - 18))
 474                         return -ENOSPC;
 475         } else {
 476                 if (found && found > (MRSTOUCH_MAX_CHANNELS - 4))
 477                         return -ENOSPC;
 478         }
 479         return found;
 480 }
 481
 482
 483 /*
 484  * Writes touch screen channels to ADC address selection registers
 485  */
 486 static int __devinit mrstouch_ts_chan_set(uint offset)
 487 {
 488         u16 chan;
 489
 490         int ret, count;
 491
 492         chan = PMICADDR0 + offset;
 493         for (count = 0; count <= 3; count++) {
 494                 ret = intel_scu_ipc_iowrite8(chan++, MRST_TS_CHAN10 + count);
 495                 if (ret)
 496                         return ret;
 497         }
 498         return intel_scu_ipc_iowrite8(chan++, END_OF_CHANNEL);
 499 }
 500
 501 /* Initialize ADC */
 502 static int __devinit mrstouch_adc_init(struct mrstouch_dev *tsdev)
 503 {
 504         int err, start;
 505         u8 ra, rm;
 506
 507         err = mrstouch_read_pmic_id(&tsdev->vendor, &tsdev->rev);
 508         if (err) {
 509                 dev_err(tsdev->dev, "Unable to read PMIC id\n");
 510                 return err;
 511         }
 512
 513         switch (tsdev->vendor) {
 514         case PMIC_VENDOR_NEC:
 515         case PMIC_VENDOR_MAXIM:
 516                 tsdev->read_prepare = mrstouch_nec_adc_read_prepare;
 517                 tsdev->read = mrstouch_nec_adc_read;
 518                 tsdev->read_finish = mrstouch_nec_adc_read_finish;
 519                 break;
 520
 521         case PMIC_VENDOR_FS:
 522                 tsdev->read_prepare = mrstouch_fs_adc_read_prepare;
 523                 tsdev->read = mrstouch_fs_adc_read;
 524                 tsdev->read_finish = mrstouch_fs_adc_read_finish;
 525                 break;
 526
 527         default:
 528                 dev_err(tsdev->dev,
 529                         "Unsupported touchscreen: %d\n", tsdev->vendor);
 530                 return -ENXIO;
 531         }
 532
 533         start = mrstouch_chan_parse(tsdev);
 534         if (start < 0) {
 535                 dev_err(tsdev->dev, "Unable to parse channels\n");
 536                 return start;
 537         }
 538
 539         tsdev->asr = start;
 540
 541         /*
 542          * ADC power on, start, enable PENDET and set loop delay
 543          * ADC loop delay is set to 4.5 ms approximately
 544          * Loop delay more than this results in jitter in adc readings
 545          * Setting loop delay to 0 (continuous loop) in MAXIM stops PENDET
 546          * interrupt generation sometimes.
 547          */
 548
 549         if (tsdev->vendor == PMIC_VENDOR_FS) {
 550                 ra = 0xE0 | ADC_LOOP_DELAY0;
 551                 rm = 0x5;
 552         } else {
 553                 /* NEC and MAXIm not consistent with loop delay 0 */
 554                 ra = 0xE0 | ADC_LOOP_DELAY1;
 555                 rm = 0x0;
 556
 557                 /* configure touch screen channels */
 558                 err = mrstouch_ts_chan_set(tsdev->asr);
 559                 if (err)
 560                         return err;
 561         }
 562
 563         err = intel_scu_ipc_update_register(PMIC_REG_ADCCNTL1, ra, 0xE7);
 564         if (err)
 565                 return err;
 566
 567         err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, rm, 0x03);
 568         if (err)
 569                 return err;
 570
 571         return 0;
 572 }
 573
 574
 575 /* Probe function for touch screen driver */
 576 static int __devinit mrstouch_probe(struct platform_device *pdev)
 577 {
 578         struct mrstouch_dev *tsdev;
 579         struct input_dev *input;
 580         int err;
 581         int irq;
 582
 583         irq = platform_get_irq(pdev, 0);
 584         if (irq < 0) {
 585                 dev_err(&pdev->dev, "no interrupt assigned\n");
 586                 return -EINVAL;
 587         }
 588
 589         tsdev = kzalloc(sizeof(struct mrstouch_dev), GFP_KERNEL);
 590         input = input_allocate_device();
 591         if (!tsdev || !input) {
 592                 dev_err(&pdev->dev, "unable to allocate memory\n");
 593                 err = -ENOMEM;
 594                 goto err_free_mem;
 595         }
 596
 597         tsdev->dev = &pdev->dev;
 598         tsdev->input = input;
 599         tsdev->irq = irq;
 600
 601         snprintf(tsdev->phys, sizeof(tsdev->phys),
 602                  "%s/input0", dev_name(tsdev->dev));
 603
 604         err = mrstouch_adc_init(tsdev);
 605         if (err) {
 606                 dev_err(&pdev->dev, "ADC initialization failed\n");
 607                 goto err_free_mem;
 608         }
 609
 610         input->name = "mrst_touchscreen";
 611         input->phys = tsdev->phys;
 612         input->dev.parent = tsdev->dev;
 613
 614         input->id.vendor = tsdev->vendor;
 615         input->id.version = tsdev->rev;
 616
 617         input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 618         input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 619
 620         input_set_abs_params(tsdev->input, ABS_X,
 621                              MRST_X_MIN, MRST_X_MAX, MRST_X_FUZZ, 0);
 622         input_set_abs_params(tsdev->input, ABS_Y,
 623                              MRST_Y_MIN, MRST_Y_MAX, MRST_Y_FUZZ, 0);
 624         input_set_abs_params(tsdev->input, ABS_PRESSURE,
 625                              MRST_PRESSURE_MIN, MRST_PRESSURE_MAX, 0, 0);
 626
 627         err = request_threaded_irq(tsdev->irq, NULL, mrstouch_pendet_irq,
 628                                    0, "mrstouch", tsdev);
 629         if (err) {
 630                 dev_err(tsdev->dev, "unable to allocate irq\n");
 631                 goto err_free_mem;
 632         }
 633
 634         err = input_register_device(tsdev->input);
 635         if (err) {
 636                 dev_err(tsdev->dev, "unable to register input device\n");
 637                 goto err_free_irq;
 638         }
 639
 640         platform_set_drvdata(pdev, tsdev);
 641         return 0;
 642
 643 err_free_irq:
 644         free_irq(tsdev->irq, tsdev);
 645 err_free_mem:
 646         input_free_device(input);
 647         kfree(tsdev);
 648         return err;
 649 }
 650
 651 static int __devexit mrstouch_remove(struct platform_device *pdev)
 652 {
 653         struct mrstouch_dev *tsdev = platform_get_drvdata(pdev);
 654
 655         free_irq(tsdev->irq, tsdev);
 656         input_unregister_device(tsdev->input);
 657         kfree(tsdev);
 658
 659         platform_set_drvdata(pdev, NULL);
 660
 661         return 0;
 662 }
 663
 664 static struct platform_driver mrstouch_driver = {
 665         .driver = {
 666                 .name   = "pmic_touch",
 667                 .owner  = THIS_MODULE,
 668         },
 669         .probe          = mrstouch_probe,
 670         .remove         = __devexit_p(mrstouch_remove),
 671 };
 672
 673 static int __init mrstouch_init(void)
 674 {
 675         return platform_driver_register(&mrstouch_driver);
 676 }
 677 module_init(mrstouch_init);
 678
 679 static void __exit mrstouch_exit(void)
 680 {
 681         platform_driver_unregister(&mrstouch_driver);
 682 }
 683 module_exit(mrstouch_exit);
 684
 685 MODULE_AUTHOR("Sreedhara Murthy. D.S, sreedhara.ds@intel.com");
 686 MODULE_DESCRIPTION("Intel Moorestown Resistive Touch Screen Driver");
 687 MODULE_LICENSE("GPL");