drivers/input/touchscreen/ads7846.c

   1 /*
   2  * ADS7846 based touchscreen and sensor driver
   3  *
   4  * Copyright (c) 2005 David Brownell
   5  * Copyright (c) 2006 Nokia Corporation
   6  * Various changes: Imre Deak <imre.deak@nokia.com>
   7  *
   8  * Using code from:
   9  *  - corgi_ts.c
  10  *      Copyright (C) 2004-2005 Richard Purdie
  11  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  12  *      Copyright (C) 2002 MontaVista Software
  13  *      Copyright (C) 2004 Texas Instruments
  14  *      Copyright (C) 2005 Dirk Behme
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License version 2 as
  18  *  published by the Free Software Foundation.
  19  */
  20 #include <linux/hwmon.h>
  21 #include <linux/init.h>
  22 #include <linux/err.h>
  23 #include <linux/delay.h>
  24 #include <linux/input.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/slab.h>
  27 #include <linux/spi/spi.h>
  28 #include <linux/spi/ads7846.h>
  29 #include <asm/irq.h>
  30
  31 #ifdef  CONFIG_ARM
  32 #include <asm/mach-types.h>
  33 #ifdef  CONFIG_ARCH_OMAP
  34 #include <asm/arch/gpio.h>
  35 #endif
  36 #endif
  37
  38
  39 /*
  40  * This code has been heavily tested on a Nokia 770, and lightly
  41  * tested on other ads7846 devices (OSK/Mistral, Lubbock).
  42  * Support for ads7843 and ads7845 has only been stubbed in.
  43  *
  44  * IRQ handling needs a workaround because of a shortcoming in handling
  45  * edge triggered IRQs on some platforms like the OMAP1/2. These
  46  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  47  * have to maintain our own SW IRQ disabled status. This should be
  48  * removed as soon as the affected platform's IRQ handling is fixed.
  49  *
  50  * app note sbaa036 talks in more detail about accurate sampling...
  51  * that ought to help in situations like LCDs inducing noise (which
  52  * can also be helped by using synch signals) and more generally.
  53  * This driver tries to utilize the measures described in the app
  54  * note. The strength of filtering can be set in the board-* specific
  55  * files.
  56  */
  57
  58 #define TS_POLL_PERIOD  msecs_to_jiffies(10)
  59
  60 /* this driver doesn't aim at the peak continuous sample rate */
  61 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  62
  63 struct ts_event {
  64         /* For portability, we can't read 12 bit values using SPI (which
  65          * would make the controller deliver them as native byteorder u16
  66          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  67          * which need byteswapping then range adjustment.
  68          */
  69         __be16 x;
  70         __be16 y;
  71         __be16 z1, z2;
  72         int    ignore;
  73 };
  74
  75 struct ads7846 {
  76         struct input_dev        *input;
  77         char                    phys[32];
  78
  79         struct spi_device       *spi;
  80         struct class_device     *hwmon;
  81         u16                     model;
  82         u16                     vref_delay_usecs;
  83         u16                     x_plate_ohms;
  84         u16                     pressure_max;
  85
  86         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  87         u16                     dummy;          /* for the pwrdown read */
  88         struct ts_event         tc;
  89
  90         struct spi_transfer     xfer[10];
  91         struct spi_message      msg[5];
  92         struct spi_message      *last_msg;
  93         int                     msg_idx;
  94         int                     read_cnt;
  95         int                     read_rep;
  96         int                     last_read;
  97
  98         u16                     debounce_max;
  99         u16                     debounce_tol;
 100         u16                     debounce_rep;
 101
 102         spinlock_t              lock;
 103         struct timer_list       timer;          /* P: lock */
 104         unsigned                pendown:1;      /* P: lock */
 105         unsigned                pending:1;      /* P: lock */
 106 // FIXME remove "irq_disabled"
 107         unsigned                irq_disabled:1; /* P: lock */
 108         unsigned                disabled:1;
 109
 110         int                     (*get_pendown_state)(void);
 111 };
 112
 113 /* leave chip selected when we're done, for quicker re-select? */
 114 #if     0
 115 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 116 #else
 117 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 118 #endif
 119
 120 /*--------------------------------------------------------------------------*/
 121
 122 /* The ADS7846 has touchscreen and other sensors.
 123  * Earlier ads784x chips are somewhat compatible.
 124  */
 125 #define ADS_START               (1 << 7)
 126 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 127 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 128 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 129 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 130 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 131 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 132 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 133 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 134 #define ADS_8_BIT               (1 << 3)
 135 #define ADS_12_BIT              (0 << 3)
 136 #define ADS_SER                 (1 << 2)        /* non-differential */
 137 #define ADS_DFR                 (0 << 2)        /* differential */
 138 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 139 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 140 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 141 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 142
 143 #define MAX_12BIT       ((1<<12)-1)
 144
 145 /* leave ADC powered up (disables penirq) between differential samples */
 146 #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
 147         | ADS_12_BIT | ADS_DFR)
 148
 149 #define READ_Y  (READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON)
 150 #define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
 151 #define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
 152
 153 #define READ_X  (READ_12BIT_DFR(x)  | ADS_PD10_ADC_ON)
 154 #define PWRDOWN (READ_12BIT_DFR(y)  | ADS_PD10_PDOWN)   /* LAST */
 155
 156 /* single-ended samples need to first power up reference voltage;
 157  * we leave both ADC and VREF powered
 158  */
 159 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 160         | ADS_12_BIT | ADS_SER)
 161
 162 #define REF_ON  (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
 163 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
 164
 165 /*--------------------------------------------------------------------------*/
 166
 167 /*
 168  * Non-touchscreen sensors only use single-ended conversions.
 169  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 170  * ads7846 lets that pin be unconnected, to use internal vREF.
 171  *
 172  * FIXME make external vREF_mV be a module option, and use that as needed...
 173  */
 174 static const unsigned vREF_mV = 2500;
 175
 176 struct ser_req {
 177         u8                      ref_on;
 178         u8                      command;
 179         u8                      ref_off;
 180         u16                     scratch;
 181         __be16                  sample;
 182         struct spi_message      msg;
 183         struct spi_transfer     xfer[6];
 184 };
 185
 186 static void ads7846_enable(struct ads7846 *ts);
 187 static void ads7846_disable(struct ads7846 *ts);
 188
 189 static int device_suspended(struct device *dev)
 190 {
 191         struct ads7846 *ts = dev_get_drvdata(dev);
 192         return dev->power.power_state.event != PM_EVENT_ON || ts->disabled;
 193 }
 194
 195 static int ads7846_read12_ser(struct device *dev, unsigned command)
 196 {
 197         struct spi_device       *spi = to_spi_device(dev);
 198         struct ads7846          *ts = dev_get_drvdata(dev);
 199         struct ser_req          *req = kzalloc(sizeof *req, SLAB_KERNEL);
 200         int                     status;
 201         int                     sample;
 202         int                     use_internal;
 203
 204         if (!req)
 205                 return -ENOMEM;
 206
 207         spi_message_init(&req->msg);
 208
 209         /* FIXME boards with ads7846 might use external vref instead ... */
 210         use_internal = (ts->model == 7846);
 211
 212         /* maybe turn on internal vREF, and let it settle */
 213         if (use_internal) {
 214                 req->ref_on = REF_ON;
 215                 req->xfer[0].tx_buf = &req->ref_on;
 216                 req->xfer[0].len = 1;
 217                 spi_message_add_tail(&req->xfer[0], &req->msg);
 218
 219                 req->xfer[1].rx_buf = &req->scratch;
 220                 req->xfer[1].len = 2;
 221
 222                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 223                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 224                 spi_message_add_tail(&req->xfer[1], &req->msg);
 225         }
 226
 227         /* take sample */
 228         req->command = (u8) command;
 229         req->xfer[2].tx_buf = &req->command;
 230         req->xfer[2].len = 1;
 231         spi_message_add_tail(&req->xfer[2], &req->msg);
 232
 233         req->xfer[3].rx_buf = &req->sample;
 234         req->xfer[3].len = 2;
 235         spi_message_add_tail(&req->xfer[3], &req->msg);
 236
 237         /* REVISIT:  take a few more samples, and compare ... */
 238
 239         /* maybe off internal vREF */
 240         if (use_internal) {
 241                 req->ref_off = REF_OFF;
 242                 req->xfer[4].tx_buf = &req->ref_off;
 243                 req->xfer[4].len = 1;
 244                 spi_message_add_tail(&req->xfer[4], &req->msg);
 245
 246                 req->xfer[5].rx_buf = &req->scratch;
 247                 req->xfer[5].len = 2;
 248                 CS_CHANGE(req->xfer[5]);
 249                 spi_message_add_tail(&req->xfer[5], &req->msg);
 250         }
 251
 252         ts->irq_disabled = 1;
 253         disable_irq(spi->irq);
 254         status = spi_sync(spi, &req->msg);
 255         ts->irq_disabled = 0;
 256         enable_irq(spi->irq);
 257
 258         if (req->msg.status)
 259                 status = req->msg.status;
 260
 261         /* on-wire is a must-ignore bit, a BE12 value, then padding */
 262         sample = be16_to_cpu(req->sample);
 263         sample = sample >> 3;
 264         sample &= 0x0fff;
 265
 266         kfree(req);
 267         return status ? status : sample;
 268 }
 269
 270 #define SHOW(name,var,adjust) static ssize_t \
 271 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 272 { \
 273         struct ads7846 *ts = dev_get_drvdata(dev); \
 274         ssize_t v = ads7846_read12_ser(dev, \
 275                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 276         if (v < 0) \
 277                 return v; \
 278         return sprintf(buf, "%u\n", adjust(ts, v)); \
 279 } \
 280 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 281
 282
 283 /* Sysfs conventions report temperatures in millidegrees Celcius.
 284  * We could use the low-accuracy two-sample scheme, but can't do the high
 285  * accuracy scheme without calibration data.  For now we won't try either;
 286  * userspace sees raw sensor values, and must scale appropriately.
 287  */
 288 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 289 {
 290         return v;
 291 }
 292
 293 SHOW(temp0, temp0, null_adjust)         // temp1_input
 294 SHOW(temp1, temp1, null_adjust)         // temp2_input
 295
 296
 297 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 298  * if we know vREF.  userspace may need to scale vAUX to match the board's
 299  * external resistors; we assume that vBATT only uses the internal ones.
 300  */
 301 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 302 {
 303         unsigned retval = v;
 304
 305         /* external resistors may scale vAUX into 0..vREF */
 306         retval *= vREF_mV;
 307         retval = retval >> 12;
 308         return retval;
 309 }
 310
 311 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 312 {
 313         unsigned retval = vaux_adjust(ts, v);
 314
 315         /* ads7846 has a resistor ladder to scale this signal down */
 316         if (ts->model == 7846)
 317                 retval *= 4;
 318         return retval;
 319 }
 320
 321 SHOW(in0_input, vaux, vaux_adjust)
 322 SHOW(in1_input, vbatt, vbatt_adjust)
 323
 324
 325 static int is_pen_down(struct device *dev)
 326 {
 327         struct ads7846          *ts = dev_get_drvdata(dev);
 328
 329         return ts->pendown;
 330 }
 331
 332 static ssize_t ads7846_pen_down_show(struct device *dev,
 333                                      struct device_attribute *attr, char *buf)
 334 {
 335         return sprintf(buf, "%u\n", is_pen_down(dev));
 336 }
 337
 338 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 339
 340 static ssize_t ads7846_disable_show(struct device *dev,
 341                                      struct device_attribute *attr, char *buf)
 342 {
 343         struct ads7846  *ts = dev_get_drvdata(dev);
 344
 345         return sprintf(buf, "%u\n", ts->disabled);
 346 }
 347
 348 static ssize_t ads7846_disable_store(struct device *dev,
 349                                      struct device_attribute *attr,
 350                                      const char *buf, size_t count)
 351 {
 352         struct ads7846 *ts = dev_get_drvdata(dev);
 353         char *endp;
 354         int i;
 355
 356         i = simple_strtoul(buf, &endp, 10);
 357         spin_lock_irq(&ts->lock);
 358
 359         if (i)
 360                 ads7846_disable(ts);
 361         else
 362                 ads7846_enable(ts);
 363
 364         spin_unlock_irq(&ts->lock);
 365
 366         return count;
 367 }
 368
 369 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 370
 371 /*--------------------------------------------------------------------------*/
 372
 373 /*
 374  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 375  * to retrieve touchscreen status.
 376  *
 377  * The SPI transfer completion callback does the real work.  It reports
 378  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 379  */
 380
 381 static void ads7846_rx(void *ads)
 382 {
 383         struct ads7846          *ts = ads;
 384         struct input_dev        *input_dev = ts->input;
 385         unsigned                Rt;
 386         unsigned                sync = 0;
 387         u16                     x, y, z1, z2;
 388         unsigned long           flags;
 389
 390         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 391          * built from two 8 bit values written msb-first.
 392          */
 393         x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff;
 394         y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff;
 395         z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff;
 396         z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff;
 397
 398         /* range filtering */
 399         if (x == MAX_12BIT)
 400                 x = 0;
 401
 402         if (likely(x && z1 && !device_suspended(&ts->spi->dev))) {
 403                 /* compute touch pressure resistance using equation #2 */
 404                 Rt = z2;
 405                 Rt -= z1;
 406                 Rt *= x;
 407                 Rt *= ts->x_plate_ohms;
 408                 Rt /= z1;
 409                 Rt = (Rt + 2047) >> 12;
 410         } else
 411                 Rt = 0;
 412
 413         /* Sample found inconsistent by debouncing or pressure is beyond
 414         * the maximum. Don't report it to user space, repeat at least
 415         * once more the measurement */
 416         if (ts->tc.ignore || Rt > ts->pressure_max) {
 417                 mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
 418                 return;
 419         }
 420
 421         /* NOTE:  "pendown" is inferred from pressure; we don't rely on
 422          * being able to check nPENIRQ status, or "friendly" trigger modes
 423          * (both-edges is much better than just-falling or low-level).
 424          *
 425          * REVISIT:  some boards may require reading nPENIRQ; it's
 426          * needed on 7843.  and 7845 reads pressure differently...
 427          *
 428          * REVISIT:  the touchscreen might not be connected; this code
 429          * won't notice that, even if nPENIRQ never fires ...
 430          */
 431         if (!ts->pendown && Rt != 0) {
 432                 input_report_key(input_dev, BTN_TOUCH, 1);
 433                 sync = 1;
 434         } else if (ts->pendown && Rt == 0) {
 435                 input_report_key(input_dev, BTN_TOUCH, 0);
 436                 sync = 1;
 437         }
 438
 439         if (Rt) {
 440                 input_report_abs(input_dev, ABS_X, x);
 441                 input_report_abs(input_dev, ABS_Y, y);
 442                 sync = 1;
 443         }
 444
 445         if (sync) {
 446                 input_report_abs(input_dev, ABS_PRESSURE, Rt);
 447                 input_sync(input_dev);
 448         }
 449
 450 #ifdef  VERBOSE
 451         if (Rt || ts->pendown)
 452                 pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
 453                         x, y, Rt, Rt ? "" : " UP");
 454 #endif
 455
 456         spin_lock_irqsave(&ts->lock, flags);
 457
 458         ts->pendown = (Rt != 0);
 459         mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
 460
 461         spin_unlock_irqrestore(&ts->lock, flags);
 462 }
 463
 464 static void ads7846_debounce(void *ads)
 465 {
 466         struct ads7846          *ts = ads;
 467         struct spi_message      *m;
 468         struct spi_transfer     *t;
 469         int                     val;
 470         int                     status;
 471
 472         m = &ts->msg[ts->msg_idx];
 473         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 474         val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff;
 475         if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
 476                 /* Repeat it, if this was the first read or the read
 477                  * wasn't consistent enough. */
 478                 if (ts->read_cnt < ts->debounce_max) {
 479                         ts->last_read = val;
 480                         ts->read_cnt++;
 481                 } else {
 482                         /* Maximum number of debouncing reached and still
 483                          * not enough number of consistent readings. Abort
 484                          * the whole sample, repeat it in the next sampling
 485                          * period.
 486                          */
 487                         ts->tc.ignore = 1;
 488                         ts->read_cnt = 0;
 489                         /* Last message will contain ads7846_rx() as the
 490                          * completion function.
 491                          */
 492                         m = ts->last_msg;
 493                 }
 494                 /* Start over collecting consistent readings. */
 495                 ts->read_rep = 0;
 496         } else {
 497                 if (++ts->read_rep > ts->debounce_rep) {
 498                         /* Got a good reading for this coordinate,
 499                          * go for the next one. */
 500                         ts->tc.ignore = 0;
 501                         ts->msg_idx++;
 502                         ts->read_cnt = 0;
 503                         ts->read_rep = 0;
 504                         m++;
 505                 } else
 506                         /* Read more values that are consistent. */
 507                         ts->read_cnt++;
 508         }
 509         status = spi_async(ts->spi, m);
 510         if (status)
 511                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 512                                 status);
 513 }
 514
 515 static void ads7846_timer(unsigned long handle)
 516 {
 517         struct ads7846  *ts = (void *)handle;
 518         int             status = 0;
 519
 520         spin_lock_irq(&ts->lock);
 521
 522         if (unlikely(ts->msg_idx && !ts->pendown)) {
 523                 /* measurment cycle ended */
 524                 if (!device_suspended(&ts->spi->dev)) {
 525                         ts->irq_disabled = 0;
 526                         enable_irq(ts->spi->irq);
 527                 }
 528                 ts->pending = 0;
 529                 ts->msg_idx = 0;
 530         } else {
 531                 /* pen is still down, continue with the measurement */
 532                 ts->msg_idx = 0;
 533                 status = spi_async(ts->spi, &ts->msg[0]);
 534                 if (status)
 535                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 536         }
 537
 538         spin_unlock_irq(&ts->lock);
 539 }
 540
 541 static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
 542 {
 543         struct ads7846 *ts = handle;
 544         unsigned long flags;
 545
 546         spin_lock_irqsave(&ts->lock, flags);
 547         if (likely(ts->get_pendown_state())) {
 548                 if (!ts->irq_disabled) {
 549                         /* REVISIT irq logic for many ARM chips has cloned a
 550                          * bug wherein disabling an irq in its handler won't
 551                          * work;(it's disabled lazily, and too late to work.
 552                          * until all their irq logic is fixed, we must shadow
 553                          * that state here.
 554                          */
 555                         ts->irq_disabled = 1;
 556                         disable_irq(ts->spi->irq);
 557                         ts->pending = 1;
 558                         mod_timer(&ts->timer, jiffies);
 559                 }
 560         }
 561         spin_unlock_irqrestore(&ts->lock, flags);
 562
 563         return IRQ_HANDLED;
 564 }
 565
 566 /*--------------------------------------------------------------------------*/
 567
 568 /* Must be called with ts->lock held */
 569 static void ads7846_disable(struct ads7846 *ts)
 570 {
 571         if (ts->disabled)
 572                 return;
 573
 574         ts->disabled = 1;
 575
 576         /* are we waiting for IRQ, or polling? */
 577         if (!ts->pending) {
 578                 ts->irq_disabled = 1;
 579                 disable_irq(ts->spi->irq);
 580         } else {
 581                 /* the timer will run at least once more, and
 582                  * leave everything in a clean state, IRQ disabled
 583                  */
 584                 while (ts->pending) {
 585                         spin_unlock_irq(&ts->lock);
 586                         msleep(1);
 587                         spin_lock_irq(&ts->lock);
 588                 }
 589         }
 590
 591         /* we know the chip's in lowpower mode since we always
 592          * leave it that way after every request
 593          */
 594
 595 }
 596
 597 /* Must be called with ts->lock held */
 598 static void ads7846_enable(struct ads7846 *ts)
 599 {
 600         if (!ts->disabled)
 601                 return;
 602
 603         ts->disabled = 0;
 604         ts->irq_disabled = 0;
 605         enable_irq(ts->spi->irq);
 606 }
 607
 608 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 609 {
 610         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 611
 612         spin_lock_irq(&ts->lock);
 613
 614         spi->dev.power.power_state = message;
 615         ads7846_disable(ts);
 616
 617         spin_unlock_irq(&ts->lock);
 618
 619         return 0;
 620
 621 }
 622
 623 static int ads7846_resume(struct spi_device *spi)
 624 {
 625         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 626
 627         spin_lock_irq(&ts->lock);
 628
 629         spi->dev.power.power_state = PMSG_ON;
 630         ads7846_enable(ts);
 631
 632         spin_unlock_irq(&ts->lock);
 633
 634         return 0;
 635 }
 636
 637 static int __devinit ads7846_probe(struct spi_device *spi)
 638 {
 639         struct ads7846                  *ts;
 640         struct input_dev                *input_dev;
 641         struct class_device             *hwmon = ERR_PTR(-ENOMEM);
 642         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 643         struct spi_message              *m;
 644         struct spi_transfer             *x;
 645         int                             err;
 646
 647         if (!spi->irq) {
 648                 dev_dbg(&spi->dev, "no IRQ?\n");
 649                 return -ENODEV;
 650         }
 651
 652         if (!pdata) {
 653                 dev_dbg(&spi->dev, "no platform data?\n");
 654                 return -ENODEV;
 655         }
 656
 657         /* don't exceed max specified sample rate */
 658         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 659                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 660                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 661                 return -EINVAL;
 662         }
 663
 664         if (pdata->get_pendown_state == NULL) {
 665                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 666                 return -EINVAL;
 667         }
 668
 669         /* We'd set the wordsize to 12 bits ... except that some controllers
 670          * will then treat the 8 bit command words as 12 bits (and drop the
 671          * four MSBs of the 12 bit result).  Result: inputs must be shifted
 672          * to discard the four garbage LSBs.  (Also, not all controllers can
 673          * support 12 bit words.)
 674          */
 675
 676         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 677         input_dev = input_allocate_device();
 678         hwmon = hwmon_device_register(&spi->dev);
 679         if (!ts || !input_dev || IS_ERR(hwmon)) {
 680                 err = -ENOMEM;
 681                 goto err_free_mem;
 682         }
 683
 684         dev_set_drvdata(&spi->dev, ts);
 685         spi->dev.power.power_state = PMSG_ON;
 686         spi->mode = SPI_MODE_1;
 687         err = spi_setup(spi);
 688         if (err < 0)
 689                 goto err_free_mem;
 690
 691         ts->spi = spi;
 692         ts->input = input_dev;
 693         ts->hwmon = hwmon;
 694
 695         init_timer(&ts->timer);
 696         ts->timer.data = (unsigned long) ts;
 697         ts->timer.function = ads7846_timer;
 698
 699         spin_lock_init(&ts->lock);
 700
 701         ts->model = pdata->model ? : 7846;
 702         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 703         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 704         ts->pressure_max = pdata->pressure_max ? : ~0;
 705         if (pdata->debounce_max) {
 706                 ts->debounce_max = pdata->debounce_max;
 707                 ts->debounce_tol = pdata->debounce_tol;
 708                 ts->debounce_rep = pdata->debounce_rep;
 709                 if (ts->debounce_rep > ts->debounce_max + 1)
 710                         ts->debounce_rep = ts->debounce_max - 1;
 711         } else
 712                 ts->debounce_tol = ~0;
 713         ts->get_pendown_state = pdata->get_pendown_state;
 714
 715         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 716
 717         input_dev->name = "ADS784x Touchscreen";
 718         input_dev->phys = ts->phys;
 719         input_dev->cdev.dev = &spi->dev;
 720
 721         input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 722         input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 723         input_set_abs_params(input_dev, ABS_X,
 724                         pdata->x_min ? : 0,
 725                         pdata->x_max ? : MAX_12BIT,
 726                         0, 0);
 727         input_set_abs_params(input_dev, ABS_Y,
 728                         pdata->y_min ? : 0,
 729                         pdata->y_max ? : MAX_12BIT,
 730                         0, 0);
 731         input_set_abs_params(input_dev, ABS_PRESSURE,
 732                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 733
 734         /* set up the transfers to read touchscreen state; this assumes we
 735          * use formula #2 for pressure, not #3.
 736          */
 737         m = &ts->msg[0];
 738         x = ts->xfer;
 739
 740         spi_message_init(m);
 741
 742         /* y- still on; turn on only y+ (and ADC) */
 743         ts->read_y = READ_Y;
 744         x->tx_buf = &ts->read_y;
 745         x->len = 1;
 746         spi_message_add_tail(x, m);
 747
 748         x++;
 749         x->rx_buf = &ts->tc.y;
 750         x->len = 2;
 751         spi_message_add_tail(x, m);
 752
 753         m->complete = ads7846_debounce;
 754         m->context = ts;
 755
 756         m++;
 757         spi_message_init(m);
 758
 759         /* turn y- off, x+ on, then leave in lowpower */
 760         x++;
 761         ts->read_x = READ_X;
 762         x->tx_buf = &ts->read_x;
 763         x->len = 1;
 764         spi_message_add_tail(x, m);
 765
 766         x++;
 767         x->rx_buf = &ts->tc.x;
 768         x->len = 2;
 769         spi_message_add_tail(x, m);
 770
 771         m->complete = ads7846_debounce;
 772         m->context = ts;
 773
 774         /* turn y+ off, x- on; we'll use formula #2 */
 775         if (ts->model == 7846) {
 776                 m++;
 777                 spi_message_init(m);
 778
 779                 x++;
 780                 ts->read_z1 = READ_Z1;
 781                 x->tx_buf = &ts->read_z1;
 782                 x->len = 1;
 783                 spi_message_add_tail(x, m);
 784
 785                 x++;
 786                 x->rx_buf = &ts->tc.z1;
 787                 x->len = 2;
 788                 spi_message_add_tail(x, m);
 789
 790                 m->complete = ads7846_debounce;
 791                 m->context = ts;
 792
 793                 m++;
 794                 spi_message_init(m);
 795
 796                 x++;
 797                 ts->read_z2 = READ_Z2;
 798                 x->tx_buf = &ts->read_z2;
 799                 x->len = 1;
 800                 spi_message_add_tail(x, m);
 801
 802                 x++;
 803                 x->rx_buf = &ts->tc.z2;
 804                 x->len = 2;
 805                 spi_message_add_tail(x, m);
 806
 807                 m->complete = ads7846_debounce;
 808                 m->context = ts;
 809         }
 810
 811         /* power down */
 812         m++;
 813         spi_message_init(m);
 814
 815         x++;
 816         ts->pwrdown = PWRDOWN;
 817         x->tx_buf = &ts->pwrdown;
 818         x->len = 1;
 819         spi_message_add_tail(x, m);
 820
 821         x++;
 822         x->rx_buf = &ts->dummy;
 823         x->len = 2;
 824         CS_CHANGE(*x);
 825         spi_message_add_tail(x, m);
 826
 827         m->complete = ads7846_rx;
 828         m->context = ts;
 829
 830         ts->last_msg = m;
 831
 832         if (request_irq(spi->irq, ads7846_irq,
 833                         SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING,
 834                         spi->dev.bus_id, ts)) {
 835                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
 836                 err = -EBUSY;
 837                 goto err_free_mem;
 838         }
 839
 840         dev_info(&spi->dev, "touchscreen + hwmon, irq %d\n", spi->irq);
 841
 842         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
 843          * the touchscreen, in case it's not connected.
 844          */
 845         (void) ads7846_read12_ser(&spi->dev,
 846                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
 847
 848         /* ads7843/7845 don't have temperature sensors, and
 849          * use the other ADC lines a bit differently too
 850          */
 851         if (ts->model == 7846) {
 852                 device_create_file(&spi->dev, &dev_attr_temp0);
 853                 device_create_file(&spi->dev, &dev_attr_temp1);
 854         }
 855         /* in1 == vBAT (7846), or a non-scaled ADC input */
 856         if (ts->model != 7845)
 857                 device_create_file(&spi->dev, &dev_attr_in1_input);
 858         /* in0 == a non-scaled ADC input */
 859         device_create_file(&spi->dev, &dev_attr_in0_input);
 860
 861         /* non-hwmon device attributes */
 862         device_create_file(&spi->dev, &dev_attr_pen_down);
 863         device_create_file(&spi->dev, &dev_attr_disable);
 864
 865         err = input_register_device(input_dev);
 866         if (err)
 867                 goto err_remove_attr;
 868
 869         return 0;
 870
 871  err_remove_attr:
 872         device_remove_file(&spi->dev, &dev_attr_disable);
 873         device_remove_file(&spi->dev, &dev_attr_pen_down);
 874         if (ts->model == 7846) {
 875                 device_remove_file(&spi->dev, &dev_attr_temp1);
 876                 device_remove_file(&spi->dev, &dev_attr_temp0);
 877         }
 878         if (ts->model != 7845)
 879                 device_remove_file(&spi->dev, &dev_attr_in1_input);
 880         device_remove_file(&spi->dev, &dev_attr_in0_input);
 881
 882         free_irq(spi->irq, ts);
 883  err_free_mem:
 884         if (!IS_ERR(hwmon))
 885                 hwmon_device_unregister(hwmon);
 886         input_free_device(input_dev);
 887         kfree(ts);
 888         return err;
 889 }
 890
 891 static int __devexit ads7846_remove(struct spi_device *spi)
 892 {
 893         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
 894
 895         hwmon_device_unregister(ts->hwmon);
 896         input_unregister_device(ts->input);
 897
 898         ads7846_suspend(spi, PMSG_SUSPEND);
 899
 900         device_remove_file(&spi->dev, &dev_attr_disable);
 901         device_remove_file(&spi->dev, &dev_attr_pen_down);
 902         if (ts->model == 7846) {
 903                 device_remove_file(&spi->dev, &dev_attr_temp1);
 904                 device_remove_file(&spi->dev, &dev_attr_temp0);
 905         }
 906         if (ts->model != 7845)
 907                 device_remove_file(&spi->dev, &dev_attr_in1_input);
 908         device_remove_file(&spi->dev, &dev_attr_in0_input);
 909
 910         free_irq(ts->spi->irq, ts);
 911         /* suspend left the IRQ disabled */
 912         enable_irq(ts->spi->irq);
 913
 914         kfree(ts);
 915
 916         dev_dbg(&spi->dev, "unregistered touchscreen\n");
 917         return 0;
 918 }
 919
 920 static struct spi_driver ads7846_driver = {
 921         .driver = {
 922                 .name   = "ads7846",
 923                 .bus    = &spi_bus_type,
 924                 .owner  = THIS_MODULE,
 925         },
 926         .probe          = ads7846_probe,
 927         .remove         = __devexit_p(ads7846_remove),
 928         .suspend        = ads7846_suspend,
 929         .resume         = ads7846_resume,
 930 };
 931
 932 static int __init ads7846_init(void)
 933 {
 934         /* grr, board-specific init should stay out of drivers!! */
 935
 936 #ifdef  CONFIG_ARCH_OMAP
 937         if (machine_is_omap_osk()) {
 938                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
 939                 omap_request_gpio(4);
 940                 omap_set_gpio_direction(4, 1);
 941                 omap_request_gpio(6);
 942                 omap_set_gpio_direction(6, 1);
 943         }
 944         // also TI 1510 Innovator, bitbanging through FPGA
 945         // also Nokia 770
 946         // also Palm Tungsten T2
 947 #endif
 948
 949         // PXA:
 950         // also Dell Axim X50
 951         // also HP iPaq H191x/H192x/H415x/H435x
 952         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
 953         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
 954
 955         // Atmel at91sam9261-EK uses ads7843
 956
 957         // also various AMD Au1x00 devel boards
 958
 959         return spi_register_driver(&ads7846_driver);
 960 }
 961 device_initcall(ads7846_init);
 962
 963 static void __exit ads7846_exit(void)
 964 {
 965         spi_unregister_driver(&ads7846_driver);
 966
 967 #ifdef  CONFIG_ARCH_OMAP
 968         if (machine_is_omap_osk()) {
 969                 omap_free_gpio(4);
 970                 omap_free_gpio(6);
 971         }
 972 #endif
 973
 974 }
 975 module_exit(ads7846_exit);
 976
 977 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
 978 MODULE_LICENSE("GPL");