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_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  59 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  60
  61 /* this driver doesn't aim at the peak continuous sample rate */
  62 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  63
  64 struct ts_event {
  65         /* For portability, we can't read 12 bit values using SPI (which
  66          * would make the controller deliver them as native byteorder u16
  67          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  68          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  69          */
  70         u16     x;
  71         u16     y;
  72         u16     z1, z2;
  73         int     ignore;
  74 };
  75
  76 struct ads7846 {
  77         struct input_dev        *input;
  78         char                    phys[32];
  79
  80         struct spi_device       *spi;
  81
  82 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  83         struct attribute_group  *attr_group;
  84         struct class_device     *hwmon;
  85 #endif
  86
  87         u16                     model;
  88         u16                     vref_delay_usecs;
  89         u16                     x_plate_ohms;
  90         u16                     pressure_max;
  91
  92         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  93         u16                     dummy;          /* for the pwrdown read */
  94         struct ts_event         tc;
  95
  96         struct spi_transfer     xfer[10];
  97         struct spi_message      msg[5];
  98         struct spi_message      *last_msg;
  99         int                     msg_idx;
 100         int                     read_cnt;
 101         int                     read_rep;
 102         int                     last_read;
 103
 104         u16                     debounce_max;
 105         u16                     debounce_tol;
 106         u16                     debounce_rep;
 107
 108         spinlock_t              lock;
 109         struct hrtimer          timer;
 110         unsigned                pendown:1;      /* P: lock */
 111         unsigned                pending:1;      /* P: lock */
 112 // FIXME remove "irq_disabled"
 113         unsigned                irq_disabled:1; /* P: lock */
 114         unsigned                disabled:1;
 115
 116         int                     (*filter)(void *data, int data_idx, int *val);
 117         void                    *filter_data;
 118         void                    (*filter_cleanup)(void *data);
 119         int                     (*get_pendown_state)(void);
 120 };
 121
 122 /* leave chip selected when we're done, for quicker re-select? */
 123 #if     0
 124 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 125 #else
 126 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 127 #endif
 128
 129 /*--------------------------------------------------------------------------*/
 130
 131 /* The ADS7846 has touchscreen and other sensors.
 132  * Earlier ads784x chips are somewhat compatible.
 133  */
 134 #define ADS_START               (1 << 7)
 135 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 136 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 137 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 138 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 139 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 140 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 141 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 142 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 143 #define ADS_8_BIT               (1 << 3)
 144 #define ADS_12_BIT              (0 << 3)
 145 #define ADS_SER                 (1 << 2)        /* non-differential */
 146 #define ADS_DFR                 (0 << 2)        /* differential */
 147 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 148 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 149 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 150 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 151
 152 #define MAX_12BIT       ((1<<12)-1)
 153
 154 /* leave ADC powered up (disables penirq) between differential samples */
 155 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 156         | ADS_12_BIT | ADS_DFR | \
 157         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 158
 159 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 160 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 161 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 162
 163 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 164 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 165
 166 /* single-ended samples need to first power up reference voltage;
 167  * we leave both ADC and VREF powered
 168  */
 169 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 170         | ADS_12_BIT | ADS_SER)
 171
 172 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 173 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 174
 175 /*--------------------------------------------------------------------------*/
 176
 177 /*
 178  * Non-touchscreen sensors only use single-ended conversions.
 179  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 180  * ads7846 lets that pin be unconnected, to use internal vREF.
 181  */
 182 static unsigned vREF_mV;
 183 module_param(vREF_mV, uint, 0);
 184 MODULE_PARM_DESC(vREF_mV, "external vREF voltage, in milliVolts");
 185
 186 struct ser_req {
 187         u8                      ref_on;
 188         u8                      command;
 189         u8                      ref_off;
 190         u16                     scratch;
 191         __be16                  sample;
 192         struct spi_message      msg;
 193         struct spi_transfer     xfer[6];
 194 };
 195
 196 static void ads7846_enable(struct ads7846 *ts);
 197 static void ads7846_disable(struct ads7846 *ts);
 198
 199 static int device_suspended(struct device *dev)
 200 {
 201         struct ads7846 *ts = dev_get_drvdata(dev);
 202         return dev->power.power_state.event != PM_EVENT_ON || ts->disabled;
 203 }
 204
 205 static int ads7846_read12_ser(struct device *dev, unsigned command)
 206 {
 207         struct spi_device       *spi = to_spi_device(dev);
 208         struct ads7846          *ts = dev_get_drvdata(dev);
 209         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 210         int                     status;
 211         int                     sample;
 212         int                     use_internal;
 213
 214         if (!req)
 215                 return -ENOMEM;
 216
 217         spi_message_init(&req->msg);
 218
 219         /* FIXME boards with ads7846 might use external vref instead ... */
 220         use_internal = (ts->model == 7846);
 221
 222         /* maybe turn on internal vREF, and let it settle */
 223         if (use_internal) {
 224                 req->ref_on = REF_ON;
 225                 req->xfer[0].tx_buf = &req->ref_on;
 226                 req->xfer[0].len = 1;
 227                 spi_message_add_tail(&req->xfer[0], &req->msg);
 228
 229                 req->xfer[1].rx_buf = &req->scratch;
 230                 req->xfer[1].len = 2;
 231
 232                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 233                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 234                 spi_message_add_tail(&req->xfer[1], &req->msg);
 235         }
 236
 237         /* take sample */
 238         req->command = (u8) command;
 239         req->xfer[2].tx_buf = &req->command;
 240         req->xfer[2].len = 1;
 241         spi_message_add_tail(&req->xfer[2], &req->msg);
 242
 243         req->xfer[3].rx_buf = &req->sample;
 244         req->xfer[3].len = 2;
 245         spi_message_add_tail(&req->xfer[3], &req->msg);
 246
 247         /* REVISIT:  take a few more samples, and compare ... */
 248
 249         /* maybe off internal vREF */
 250         if (use_internal) {
 251                 req->ref_off = REF_OFF;
 252                 req->xfer[4].tx_buf = &req->ref_off;
 253                 req->xfer[4].len = 1;
 254                 spi_message_add_tail(&req->xfer[4], &req->msg);
 255
 256                 req->xfer[5].rx_buf = &req->scratch;
 257                 req->xfer[5].len = 2;
 258                 CS_CHANGE(req->xfer[5]);
 259                 spi_message_add_tail(&req->xfer[5], &req->msg);
 260         }
 261
 262         ts->irq_disabled = 1;
 263         disable_irq(spi->irq);
 264         status = spi_sync(spi, &req->msg);
 265         ts->irq_disabled = 0;
 266         enable_irq(spi->irq);
 267
 268         if (req->msg.status)
 269                 status = req->msg.status;
 270
 271         /* on-wire is a must-ignore bit, a BE12 value, then padding */
 272         sample = be16_to_cpu(req->sample);
 273         sample = sample >> 3;
 274         sample &= 0x0fff;
 275
 276         kfree(req);
 277         return status ? status : sample;
 278 }
 279
 280 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 281
 282 #define SHOW(name, var, adjust) static ssize_t \
 283 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 284 { \
 285         struct ads7846 *ts = dev_get_drvdata(dev); \
 286         ssize_t v = ads7846_read12_ser(dev, \
 287                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 288         if (v < 0) \
 289                 return v; \
 290         return sprintf(buf, "%u\n", adjust(ts, v)); \
 291 } \
 292 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 293
 294
 295 /* Sysfs conventions report temperatures in millidegrees Celcius.
 296  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 297  * accuracy scheme without calibration data.  For now we won't try either;
 298  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 299  */
 300 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 301 {
 302         return v;
 303 }
 304
 305 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 306 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 307
 308
 309 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 310  * if we know vREF.  userspace may need to scale vAUX to match the board's
 311  * external resistors; we assume that vBATT only uses the internal ones.
 312  */
 313 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 314 {
 315         unsigned retval = v;
 316
 317         /* external resistors may scale vAUX into 0..vREF */
 318         retval *= vREF_mV;
 319         retval = retval >> 12;
 320         return retval;
 321 }
 322
 323 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 324 {
 325         unsigned retval = vaux_adjust(ts, v);
 326
 327         /* ads7846 has a resistor ladder to scale this signal down */
 328         if (ts->model == 7846)
 329                 retval *= 4;
 330         return retval;
 331 }
 332
 333 SHOW(in0_input, vaux, vaux_adjust)
 334 SHOW(in1_input, vbatt, vbatt_adjust)
 335
 336
 337 static struct attribute *ads7846_attributes[] = {
 338         &dev_attr_temp0.attr,
 339         &dev_attr_temp1.attr,
 340         &dev_attr_in0_input.attr,
 341         &dev_attr_in1_input.attr,
 342         NULL,
 343 };
 344
 345 static struct attribute_group ads7846_attr_group = {
 346         .attrs = ads7846_attributes,
 347 };
 348
 349 static struct attribute *ads7843_attributes[] = {
 350         &dev_attr_in0_input.attr,
 351         &dev_attr_in1_input.attr,
 352         NULL,
 353 };
 354
 355 static struct attribute_group ads7843_attr_group = {
 356         .attrs = ads7843_attributes,
 357 };
 358
 359 static struct attribute *ads7845_attributes[] = {
 360         &dev_attr_in0_input.attr,
 361         NULL,
 362 };
 363
 364 static struct attribute_group ads7845_attr_group = {
 365         .attrs = ads7845_attributes,
 366 };
 367
 368 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 369 {
 370         struct class_device *hwmon;
 371         int err;
 372
 373         /* hwmon sensors need a reference voltage */
 374         switch (ts->model) {
 375         case 7846:
 376                 if (!vREF_mV) {
 377                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 378                         vREF_mV = 2500;
 379                 }
 380                 break;
 381         case 7845:
 382         case 7843:
 383                 if (!vREF_mV) {
 384                         dev_warn(&spi->dev,
 385                                 "external vREF for ADS%d not specified\n",
 386                                 ts->model);
 387                         return 0;
 388                 }
 389                 break;
 390         }
 391
 392         /* different chips have different sensor groups */
 393         switch (ts->model) {
 394         case 7846:
 395                 ts->attr_group = &ads7846_attr_group;
 396                 break;
 397         case 7845:
 398                 ts->attr_group = &ads7845_attr_group;
 399                 break;
 400         case 7843:
 401                 ts->attr_group = &ads7843_attr_group;
 402                 break;
 403         default:
 404                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 405                 return 0;
 406         }
 407
 408         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 409         if (err)
 410                 return err;
 411
 412         hwmon = hwmon_device_register(&spi->dev);
 413         if (IS_ERR(hwmon)) {
 414                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 415                 return PTR_ERR(hwmon);
 416         }
 417
 418         ts->hwmon = hwmon;
 419         return 0;
 420 }
 421
 422 static void ads784x_hwmon_unregister(struct spi_device *spi,
 423                                      struct ads7846 *ts)
 424 {
 425         if (ts->hwmon) {
 426                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 427                 hwmon_device_unregister(ts->hwmon);
 428         }
 429 }
 430
 431 #else
 432 static inline int ads784x_hwmon_register(struct spi_device *spi,
 433                                          struct ads7846 *ts)
 434 {
 435         return 0;
 436 }
 437
 438 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 439                                             struct ads7846 *ts)
 440 {
 441 }
 442 #endif
 443
 444 static int is_pen_down(struct device *dev)
 445 {
 446         struct ads7846  *ts = dev_get_drvdata(dev);
 447
 448         return ts->pendown;
 449 }
 450
 451 static ssize_t ads7846_pen_down_show(struct device *dev,
 452                                      struct device_attribute *attr, char *buf)
 453 {
 454         return sprintf(buf, "%u\n", is_pen_down(dev));
 455 }
 456
 457 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 458
 459 static ssize_t ads7846_disable_show(struct device *dev,
 460                                      struct device_attribute *attr, char *buf)
 461 {
 462         struct ads7846  *ts = dev_get_drvdata(dev);
 463
 464         return sprintf(buf, "%u\n", ts->disabled);
 465 }
 466
 467 static ssize_t ads7846_disable_store(struct device *dev,
 468                                      struct device_attribute *attr,
 469                                      const char *buf, size_t count)
 470 {
 471         struct ads7846 *ts = dev_get_drvdata(dev);
 472         char *endp;
 473         int i;
 474
 475         i = simple_strtoul(buf, &endp, 10);
 476         spin_lock_irq(&ts->lock);
 477
 478         if (i)
 479                 ads7846_disable(ts);
 480         else
 481                 ads7846_enable(ts);
 482
 483         spin_unlock_irq(&ts->lock);
 484
 485         return count;
 486 }
 487
 488 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 489
 490 static struct attribute *ads784x_attributes[] = {
 491         &dev_attr_pen_down.attr,
 492         &dev_attr_disable.attr,
 493         NULL,
 494 };
 495
 496 static struct attribute_group ads784x_attr_group = {
 497         .attrs = ads784x_attributes,
 498 };
 499
 500 /*--------------------------------------------------------------------------*/
 501
 502 /*
 503  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 504  * to retrieve touchscreen status.
 505  *
 506  * The SPI transfer completion callback does the real work.  It reports
 507  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 508  */
 509
 510 static void ads7846_rx(void *ads)
 511 {
 512         struct ads7846          *ts = ads;
 513         unsigned                Rt;
 514         u16                     x, y, z1, z2;
 515
 516         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 517          * on-the-wire format as part of debouncing to get stable readings.
 518          */
 519         x = ts->tc.x;
 520         y = ts->tc.y;
 521         z1 = ts->tc.z1;
 522         z2 = ts->tc.z2;
 523
 524         /* range filtering */
 525         if (x == MAX_12BIT)
 526                 x = 0;
 527
 528         if (likely(x && z1)) {
 529                 /* compute touch pressure resistance using equation #2 */
 530                 Rt = z2;
 531                 Rt -= z1;
 532                 Rt *= x;
 533                 Rt *= ts->x_plate_ohms;
 534                 Rt /= z1;
 535                 Rt = (Rt + 2047) >> 12;
 536         } else
 537                 Rt = 0;
 538
 539         /* Sample found inconsistent by debouncing or pressure is beyond
 540          * the maximum. Don't report it to user space, repeat at least
 541          * once more the measurement
 542          */
 543         if (ts->tc.ignore || Rt > ts->pressure_max) {
 544 #ifdef VERBOSE
 545                 pr_debug("%s: ignored %d pressure %d\n",
 546                         ts->spi->dev.bus_id, ts->tc.ignore, Rt);
 547 #endif
 548                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 549                               HRTIMER_MODE_REL);
 550                 return;
 551         }
 552
 553         /* NOTE: We can't rely on the pressure to determine the pen down
 554          * state, even this controller has a pressure sensor.  The pressure
 555          * value can fluctuate for quite a while after lifting the pen and
 556          * in some cases may not even settle at the expected value.
 557          *
 558          * The only safe way to check for the pen up condition is in the
 559          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 560          */
 561         if (Rt) {
 562                 struct input_dev *input = ts->input;
 563
 564                 if (!ts->pendown) {
 565                         input_report_key(input, BTN_TOUCH, 1);
 566                         ts->pendown = 1;
 567 #ifdef VERBOSE
 568                         dev_dbg(&ts->spi->dev, "DOWN\n");
 569 #endif
 570                 }
 571                 input_report_abs(input, ABS_X, x);
 572                 input_report_abs(input, ABS_Y, y);
 573                 input_report_abs(input, ABS_PRESSURE, Rt);
 574
 575                 input_sync(input);
 576 #ifdef VERBOSE
 577                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 578 #endif
 579         }
 580
 581         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 582                         HRTIMER_MODE_REL);
 583 }
 584
 585 static int ads7846_debounce(void *ads, int data_idx, int *val)
 586 {
 587         struct ads7846          *ts = ads;
 588
 589         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 590                 /* Start over collecting consistent readings. */
 591                 ts->read_rep = 0;
 592                 /* Repeat it, if this was the first read or the read
 593                  * wasn't consistent enough. */
 594                 if (ts->read_cnt < ts->debounce_max) {
 595                         ts->last_read = *val;
 596                         ts->read_cnt++;
 597                         return ADS7846_FILTER_REPEAT;
 598                 } else {
 599                         /* Maximum number of debouncing reached and still
 600                          * not enough number of consistent readings. Abort
 601                          * the whole sample, repeat it in the next sampling
 602                          * period.
 603                          */
 604                         ts->read_cnt = 0;
 605                         return ADS7846_FILTER_IGNORE;
 606                 }
 607         } else {
 608                 if (++ts->read_rep > ts->debounce_rep) {
 609                         /* Got a good reading for this coordinate,
 610                          * go for the next one. */
 611                         ts->read_cnt = 0;
 612                         ts->read_rep = 0;
 613                         return ADS7846_FILTER_OK;
 614                 } else {
 615                         /* Read more values that are consistent. */
 616                         ts->read_cnt++;
 617                         return ADS7846_FILTER_REPEAT;
 618                 }
 619         }
 620 }
 621
 622 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 623 {
 624         return ADS7846_FILTER_OK;
 625 }
 626
 627 static void ads7846_rx_val(void *ads)
 628 {
 629         struct ads7846 *ts = ads;
 630         struct spi_message *m;
 631         struct spi_transfer *t;
 632         u16 *rx_val;
 633         int val;
 634         int action;
 635         int status;
 636
 637         m = &ts->msg[ts->msg_idx];
 638         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 639         rx_val = t->rx_buf;
 640
 641         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 642          * built from two 8 bit values written msb-first.
 643          */
 644         val = be16_to_cpu(*rx_val) >> 3;
 645
 646         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 647         switch (action) {
 648         case ADS7846_FILTER_REPEAT:
 649                 break;
 650         case ADS7846_FILTER_IGNORE:
 651                 ts->tc.ignore = 1;
 652                 /* Last message will contain ads7846_rx() as the
 653                  * completion function.
 654                  */
 655                 m = ts->last_msg;
 656                 break;
 657         case ADS7846_FILTER_OK:
 658                 *rx_val = val;
 659                 ts->tc.ignore = 0;
 660                 m = &ts->msg[++ts->msg_idx];
 661                 break;
 662         default:
 663                 BUG();
 664         }
 665         status = spi_async(ts->spi, m);
 666         if (status)
 667                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 668                                 status);
 669 }
 670
 671 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 672 {
 673         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 674         int             status = 0;
 675
 676         spin_lock_irq(&ts->lock);
 677
 678         if (unlikely(!ts->get_pendown_state() ||
 679                      device_suspended(&ts->spi->dev))) {
 680                 if (ts->pendown) {
 681                         struct input_dev *input = ts->input;
 682
 683                         input_report_key(input, BTN_TOUCH, 0);
 684                         input_report_abs(input, ABS_PRESSURE, 0);
 685                         input_sync(input);
 686
 687                         ts->pendown = 0;
 688 #ifdef VERBOSE
 689                         dev_dbg(&ts->spi->dev, "UP\n");
 690 #endif
 691                 }
 692
 693                 /* measurement cycle ended */
 694                 if (!device_suspended(&ts->spi->dev)) {
 695                         ts->irq_disabled = 0;
 696                         enable_irq(ts->spi->irq);
 697                 }
 698                 ts->pending = 0;
 699         } else {
 700                 /* pen is still down, continue with the measurement */
 701                 ts->msg_idx = 0;
 702                 status = spi_async(ts->spi, &ts->msg[0]);
 703                 if (status)
 704                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 705         }
 706
 707         spin_unlock_irq(&ts->lock);
 708         return HRTIMER_NORESTART;
 709 }
 710
 711 static irqreturn_t ads7846_irq(int irq, void *handle)
 712 {
 713         struct ads7846 *ts = handle;
 714         unsigned long flags;
 715
 716         spin_lock_irqsave(&ts->lock, flags);
 717         if (likely(ts->get_pendown_state())) {
 718                 if (!ts->irq_disabled) {
 719                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 720                          * like the other dispatchers:  it will report IRQs
 721                          * even after they've been disabled.  We work around
 722                          * that here.  (The "generic irq" framework may help...)
 723                          */
 724                         ts->irq_disabled = 1;
 725                         disable_irq(ts->spi->irq);
 726                         ts->pending = 1;
 727                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 728                                         HRTIMER_MODE_REL);
 729                 }
 730         }
 731         spin_unlock_irqrestore(&ts->lock, flags);
 732
 733         return IRQ_HANDLED;
 734 }
 735
 736 /*--------------------------------------------------------------------------*/
 737
 738 /* Must be called with ts->lock held */
 739 static void ads7846_disable(struct ads7846 *ts)
 740 {
 741         if (ts->disabled)
 742                 return;
 743
 744         ts->disabled = 1;
 745
 746         /* are we waiting for IRQ, or polling? */
 747         if (!ts->pending) {
 748                 ts->irq_disabled = 1;
 749                 disable_irq(ts->spi->irq);
 750         } else {
 751                 /* the timer will run at least once more, and
 752                  * leave everything in a clean state, IRQ disabled
 753                  */
 754                 while (ts->pending) {
 755                         spin_unlock_irq(&ts->lock);
 756                         msleep(1);
 757                         spin_lock_irq(&ts->lock);
 758                 }
 759         }
 760
 761         /* we know the chip's in lowpower mode since we always
 762          * leave it that way after every request
 763          */
 764
 765 }
 766
 767 /* Must be called with ts->lock held */
 768 static void ads7846_enable(struct ads7846 *ts)
 769 {
 770         if (!ts->disabled)
 771                 return;
 772
 773         ts->disabled = 0;
 774         ts->irq_disabled = 0;
 775         enable_irq(ts->spi->irq);
 776 }
 777
 778 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 779 {
 780         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 781
 782         spin_lock_irq(&ts->lock);
 783
 784         spi->dev.power.power_state = message;
 785         ads7846_disable(ts);
 786
 787         spin_unlock_irq(&ts->lock);
 788
 789         return 0;
 790
 791 }
 792
 793 static int ads7846_resume(struct spi_device *spi)
 794 {
 795         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 796
 797         spin_lock_irq(&ts->lock);
 798
 799         spi->dev.power.power_state = PMSG_ON;
 800         ads7846_enable(ts);
 801
 802         spin_unlock_irq(&ts->lock);
 803
 804         return 0;
 805 }
 806
 807 static int __devinit ads7846_probe(struct spi_device *spi)
 808 {
 809         struct ads7846                  *ts;
 810         struct input_dev                *input_dev;
 811         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 812         struct spi_message              *m;
 813         struct spi_transfer             *x;
 814         int                             vref;
 815         int                             err;
 816
 817         if (!spi->irq) {
 818                 dev_dbg(&spi->dev, "no IRQ?\n");
 819                 return -ENODEV;
 820         }
 821
 822         if (!pdata) {
 823                 dev_dbg(&spi->dev, "no platform data?\n");
 824                 return -ENODEV;
 825         }
 826
 827         /* don't exceed max specified sample rate */
 828         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 829                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 830                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 831                 return -EINVAL;
 832         }
 833
 834         /* REVISIT when the irq can be triggered active-low, or if for some
 835          * reason the touchscreen isn't hooked up, we don't need to access
 836          * the pendown state.
 837          */
 838         if (pdata->get_pendown_state == NULL) {
 839                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 840                 return -EINVAL;
 841         }
 842
 843         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 844          * that even if the hardware can do that, the SPI controller driver
 845          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 846          */
 847         spi->bits_per_word = 8;
 848         spi->mode = SPI_MODE_1;
 849         err = spi_setup(spi);
 850         if (err < 0)
 851                 return err;
 852
 853         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 854         input_dev = input_allocate_device();
 855         if (!ts || !input_dev) {
 856                 err = -ENOMEM;
 857                 goto err_free_mem;
 858         }
 859
 860         dev_set_drvdata(&spi->dev, ts);
 861         spi->dev.power.power_state = PMSG_ON;
 862
 863         ts->spi = spi;
 864         ts->input = input_dev;
 865
 866         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 867         ts->timer.function = ads7846_timer;
 868
 869         spin_lock_init(&ts->lock);
 870
 871         ts->model = pdata->model ? : 7846;
 872         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 873         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 874         ts->pressure_max = pdata->pressure_max ? : ~0;
 875
 876         if (pdata->filter != NULL) {
 877                 if (pdata->filter_init != NULL) {
 878                         err = pdata->filter_init(pdata, &ts->filter_data);
 879                         if (err < 0)
 880                                 goto err_free_mem;
 881                 }
 882                 ts->filter = pdata->filter;
 883                 ts->filter_cleanup = pdata->filter_cleanup;
 884         } else if (pdata->debounce_max) {
 885                 ts->debounce_max = pdata->debounce_max;
 886                 if (ts->debounce_max < 2)
 887                         ts->debounce_max = 2;
 888                 ts->debounce_tol = pdata->debounce_tol;
 889                 ts->debounce_rep = pdata->debounce_rep;
 890                 ts->filter = ads7846_debounce;
 891                 ts->filter_data = ts;
 892         } else
 893                 ts->filter = ads7846_no_filter;
 894         ts->get_pendown_state = pdata->get_pendown_state;
 895
 896         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 897
 898         input_dev->name = "ADS784x Touchscreen";
 899         input_dev->phys = ts->phys;
 900         input_dev->cdev.dev = &spi->dev;
 901
 902         input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 903         input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 904         input_set_abs_params(input_dev, ABS_X,
 905                         pdata->x_min ? : 0,
 906                         pdata->x_max ? : MAX_12BIT,
 907                         0, 0);
 908         input_set_abs_params(input_dev, ABS_Y,
 909                         pdata->y_min ? : 0,
 910                         pdata->y_max ? : MAX_12BIT,
 911                         0, 0);
 912         input_set_abs_params(input_dev, ABS_PRESSURE,
 913                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 914
 915         vref = pdata->keep_vref_on;
 916
 917         /* set up the transfers to read touchscreen state; this assumes we
 918          * use formula #2 for pressure, not #3.
 919          */
 920         m = &ts->msg[0];
 921         x = ts->xfer;
 922
 923         spi_message_init(m);
 924
 925         /* y- still on; turn on only y+ (and ADC) */
 926         ts->read_y = READ_Y(vref);
 927         x->tx_buf = &ts->read_y;
 928         x->len = 1;
 929         spi_message_add_tail(x, m);
 930
 931         x++;
 932         x->rx_buf = &ts->tc.y;
 933         x->len = 2;
 934         spi_message_add_tail(x, m);
 935
 936         m->complete = ads7846_rx_val;
 937         m->context = ts;
 938
 939         m++;
 940         spi_message_init(m);
 941
 942         /* turn y- off, x+ on, then leave in lowpower */
 943         x++;
 944         ts->read_x = READ_X(vref);
 945         x->tx_buf = &ts->read_x;
 946         x->len = 1;
 947         spi_message_add_tail(x, m);
 948
 949         x++;
 950         x->rx_buf = &ts->tc.x;
 951         x->len = 2;
 952         spi_message_add_tail(x, m);
 953
 954         m->complete = ads7846_rx_val;
 955         m->context = ts;
 956
 957         /* turn y+ off, x- on; we'll use formula #2 */
 958         if (ts->model == 7846) {
 959                 m++;
 960                 spi_message_init(m);
 961
 962                 x++;
 963                 ts->read_z1 = READ_Z1(vref);
 964                 x->tx_buf = &ts->read_z1;
 965                 x->len = 1;
 966                 spi_message_add_tail(x, m);
 967
 968                 x++;
 969                 x->rx_buf = &ts->tc.z1;
 970                 x->len = 2;
 971                 spi_message_add_tail(x, m);
 972
 973                 m->complete = ads7846_rx_val;
 974                 m->context = ts;
 975
 976                 m++;
 977                 spi_message_init(m);
 978
 979                 x++;
 980                 ts->read_z2 = READ_Z2(vref);
 981                 x->tx_buf = &ts->read_z2;
 982                 x->len = 1;
 983                 spi_message_add_tail(x, m);
 984
 985                 x++;
 986                 x->rx_buf = &ts->tc.z2;
 987                 x->len = 2;
 988                 spi_message_add_tail(x, m);
 989
 990                 m->complete = ads7846_rx_val;
 991                 m->context = ts;
 992         }
 993
 994         /* power down */
 995         m++;
 996         spi_message_init(m);
 997
 998         x++;
 999         ts->pwrdown = PWRDOWN;
1000         x->tx_buf = &ts->pwrdown;
1001         x->len = 1;
1002         spi_message_add_tail(x, m);
1003
1004         x++;
1005         x->rx_buf = &ts->dummy;
1006         x->len = 2;
1007         CS_CHANGE(*x);
1008         spi_message_add_tail(x, m);
1009
1010         m->complete = ads7846_rx;
1011         m->context = ts;
1012
1013         ts->last_msg = m;
1014
1015         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1016                         spi->dev.driver->name, ts)) {
1017                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1018                 err = -EBUSY;
1019                 goto err_cleanup_filter;
1020         }
1021
1022         err = ads784x_hwmon_register(spi, ts);
1023         if (err)
1024                 goto err_free_irq;
1025
1026         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1027
1028         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1029          * the touchscreen, in case it's not connected.
1030          */
1031         (void) ads7846_read12_ser(&spi->dev,
1032                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1033
1034         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1035         if (err)
1036                 goto err_remove_hwmon;
1037
1038         err = input_register_device(input_dev);
1039         if (err)
1040                 goto err_remove_attr_group;
1041
1042         return 0;
1043
1044  err_remove_attr_group:
1045         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1046  err_remove_hwmon:
1047         ads784x_hwmon_unregister(spi, ts);
1048  err_free_irq:
1049         free_irq(spi->irq, ts);
1050  err_cleanup_filter:
1051         if (ts->filter_cleanup)
1052                 ts->filter_cleanup(ts->filter_data);
1053  err_free_mem:
1054         input_free_device(input_dev);
1055         kfree(ts);
1056         return err;
1057 }
1058
1059 static int __devexit ads7846_remove(struct spi_device *spi)
1060 {
1061         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1062
1063         ads784x_hwmon_unregister(spi, ts);
1064         input_unregister_device(ts->input);
1065
1066         ads7846_suspend(spi, PMSG_SUSPEND);
1067
1068         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1069
1070         free_irq(ts->spi->irq, ts);
1071         /* suspend left the IRQ disabled */
1072         enable_irq(ts->spi->irq);
1073
1074         if (ts->filter_cleanup)
1075                 ts->filter_cleanup(ts->filter_data);
1076
1077         kfree(ts);
1078
1079         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1080         return 0;
1081 }
1082
1083 static struct spi_driver ads7846_driver = {
1084         .driver = {
1085                 .name   = "ads7846",
1086                 .bus    = &spi_bus_type,
1087                 .owner  = THIS_MODULE,
1088         },
1089         .probe          = ads7846_probe,
1090         .remove         = __devexit_p(ads7846_remove),
1091         .suspend        = ads7846_suspend,
1092         .resume         = ads7846_resume,
1093 };
1094
1095 static int __init ads7846_init(void)
1096 {
1097         /* grr, board-specific init should stay out of drivers!! */
1098
1099 #ifdef  CONFIG_ARCH_OMAP
1100         if (machine_is_omap_osk()) {
1101                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
1102                 omap_request_gpio(4);
1103                 omap_set_gpio_direction(4, 1);
1104                 omap_request_gpio(6);
1105                 omap_set_gpio_direction(6, 1);
1106         }
1107         // also TI 1510 Innovator, bitbanging through FPGA
1108         // also Nokia 770
1109         // also Palm Tungsten T2
1110 #endif
1111
1112         // PXA:
1113         // also Dell Axim X50
1114         // also HP iPaq H191x/H192x/H415x/H435x
1115         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
1116         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
1117
1118         // Atmel at91sam9261-EK uses ads7843
1119
1120         // also various AMD Au1x00 devel boards
1121
1122         return spi_register_driver(&ads7846_driver);
1123 }
1124 module_init(ads7846_init);
1125
1126 static void __exit ads7846_exit(void)
1127 {
1128         spi_unregister_driver(&ads7846_driver);
1129
1130 #ifdef  CONFIG_ARCH_OMAP
1131         if (machine_is_omap_osk()) {
1132                 omap_free_gpio(4);
1133                 omap_free_gpio(6);
1134         }
1135 #endif
1136
1137 }
1138 module_exit(ads7846_exit);
1139
1140 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1141 MODULE_LICENSE("GPL");