git.oblomov.eu Git - linux-2.6/blob - 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
  32 /*
  33  * This code has been heavily tested on a Nokia 770, and lightly
  34  * tested on other ads7846 devices (OSK/Mistral, Lubbock).
  35  * TSC2046 is just newer ads7846 silicon.
  36  * Support for ads7843 tested on Atmel at91sam926x-EK.
  37  * Support for ads7845 has only been stubbed in.
  38  *
  39  * IRQ handling needs a workaround because of a shortcoming in handling
  40  * edge triggered IRQs on some platforms like the OMAP1/2. These
  41  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  42  * have to maintain our own SW IRQ disabled status. This should be
  43  * removed as soon as the affected platform's IRQ handling is fixed.
  44  *
  45  * app note sbaa036 talks in more detail about accurate sampling...
  46  * that ought to help in situations like LCDs inducing noise (which
  47  * can also be helped by using synch signals) and more generally.
  48  * This driver tries to utilize the measures described in the app
  49  * note. The strength of filtering can be set in the board-* specific
  50  * files.
  51  */
  52
  53 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  54 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  55
  56 /* this driver doesn't aim at the peak continuous sample rate */
  57 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  58
  59 struct ts_event {
  60         /* For portability, we can't read 12 bit values using SPI (which
  61          * would make the controller deliver them as native byteorder u16
  62          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  63          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  64          */
  65         u16     x;
  66         u16     y;
  67         u16     z1, z2;
  68         int     ignore;
  69 };
  70
  71 struct ads7846 {
  72         struct input_dev        *input;
  73         char                    phys[32];
  74
  75         struct spi_device       *spi;
  76
  77 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  78         struct attribute_group  *attr_group;
  79         struct device           *hwmon;
  80 #endif
  81
  82         u16                     model;
  83         u16                     vref_mv;
  84         u16                     vref_delay_usecs;
  85         u16                     x_plate_ohms;
  86         u16                     pressure_max;
  87
  88         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  89         u16                     dummy;          /* for the pwrdown read */
  90         struct ts_event         tc;
  91
  92         struct spi_transfer     xfer[18];
  93         struct spi_message      msg[5];
  94         struct spi_message      *last_msg;
  95         int                     msg_idx;
  96         int                     read_cnt;
  97         int                     read_rep;
  98         int                     last_read;
  99
 100         u16                     debounce_max;
 101         u16                     debounce_tol;
 102         u16                     debounce_rep;
 103
 104         u16                     penirq_recheck_delay_usecs;
 105
 106         spinlock_t              lock;
 107         struct hrtimer          timer;
 108         unsigned                pendown:1;      /* P: lock */
 109         unsigned                pending:1;      /* P: lock */
 110 // FIXME remove "irq_disabled"
 111         unsigned                irq_disabled:1; /* P: lock */
 112         unsigned                disabled:1;
 113         unsigned                is_suspended:1;
 114
 115         int                     (*filter)(void *data, int data_idx, int *val);
 116         void                    *filter_data;
 117         void                    (*filter_cleanup)(void *data);
 118         int                     (*get_pendown_state)(void);
 119 };
 120
 121 /* leave chip selected when we're done, for quicker re-select? */
 122 #if     0
 123 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 124 #else
 125 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 126 #endif
 127
 128 /*--------------------------------------------------------------------------*/
 129
 130 /* The ADS7846 has touchscreen and other sensors.
 131  * Earlier ads784x chips are somewhat compatible.
 132  */
 133 #define ADS_START               (1 << 7)
 134 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 135 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 136 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 137 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 138 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 139 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 140 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 141 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 142 #define ADS_8_BIT               (1 << 3)
 143 #define ADS_12_BIT              (0 << 3)
 144 #define ADS_SER                 (1 << 2)        /* non-differential */
 145 #define ADS_DFR                 (0 << 2)        /* differential */
 146 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 147 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 148 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 149 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 150
 151 #define MAX_12BIT       ((1<<12)-1)
 152
 153 /* leave ADC powered up (disables penirq) between differential samples */
 154 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 155         | ADS_12_BIT | ADS_DFR | \
 156         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 157
 158 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 159 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 160 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 161
 162 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 163 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 164
 165 /* single-ended samples need to first power up reference voltage;
 166  * we leave both ADC and VREF powered
 167  */
 168 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 169         | ADS_12_BIT | ADS_SER)
 170
 171 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 172 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 173
 174 /*--------------------------------------------------------------------------*/
 175
 176 /*
 177  * Non-touchscreen sensors only use single-ended conversions.
 178  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 179  * ads7846 lets that pin be unconnected, to use internal vREF.
 180  */
 181
 182 struct ser_req {
 183         u8                      ref_on;
 184         u8                      command;
 185         u8                      ref_off;
 186         u16                     scratch;
 187         __be16                  sample;
 188         struct spi_message      msg;
 189         struct spi_transfer     xfer[6];
 190 };
 191
 192 static void ads7846_enable(struct ads7846 *ts);
 193 static void ads7846_disable(struct ads7846 *ts);
 194
 195 static int device_suspended(struct device *dev)
 196 {
 197         struct ads7846 *ts = dev_get_drvdata(dev);
 198         return ts->is_suspended || ts->disabled;
 199 }
 200
 201 static int ads7846_read12_ser(struct device *dev, unsigned command)
 202 {
 203         struct spi_device       *spi = to_spi_device(dev);
 204         struct ads7846          *ts = dev_get_drvdata(dev);
 205         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 206         int                     status;
 207         int                     use_internal;
 208
 209         if (!req)
 210                 return -ENOMEM;
 211
 212         spi_message_init(&req->msg);
 213
 214         /* FIXME boards with ads7846 might use external vref instead ... */
 215         use_internal = (ts->model == 7846);
 216
 217         /* maybe turn on internal vREF, and let it settle */
 218         if (use_internal) {
 219                 req->ref_on = REF_ON;
 220                 req->xfer[0].tx_buf = &req->ref_on;
 221                 req->xfer[0].len = 1;
 222                 spi_message_add_tail(&req->xfer[0], &req->msg);
 223
 224                 req->xfer[1].rx_buf = &req->scratch;
 225                 req->xfer[1].len = 2;
 226
 227                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 228                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 229                 spi_message_add_tail(&req->xfer[1], &req->msg);
 230         }
 231
 232         /* take sample */
 233         req->command = (u8) command;
 234         req->xfer[2].tx_buf = &req->command;
 235         req->xfer[2].len = 1;
 236         spi_message_add_tail(&req->xfer[2], &req->msg);
 237
 238         req->xfer[3].rx_buf = &req->sample;
 239         req->xfer[3].len = 2;
 240         spi_message_add_tail(&req->xfer[3], &req->msg);
 241
 242         /* REVISIT:  take a few more samples, and compare ... */
 243
 244         /* converter in low power mode & enable PENIRQ */
 245         req->ref_off = PWRDOWN;
 246         req->xfer[4].tx_buf = &req->ref_off;
 247         req->xfer[4].len = 1;
 248         spi_message_add_tail(&req->xfer[4], &req->msg);
 249
 250         req->xfer[5].rx_buf = &req->scratch;
 251         req->xfer[5].len = 2;
 252         CS_CHANGE(req->xfer[5]);
 253         spi_message_add_tail(&req->xfer[5], &req->msg);
 254
 255         ts->irq_disabled = 1;
 256         disable_irq(spi->irq);
 257         status = spi_sync(spi, &req->msg);
 258         ts->irq_disabled = 0;
 259         enable_irq(spi->irq);
 260
 261         if (status == 0) {
 262                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 263                 status = be16_to_cpu(req->sample);
 264                 status = status >> 3;
 265                 status &= 0x0fff;
 266         }
 267
 268         kfree(req);
 269         return status;
 270 }
 271
 272 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 273
 274 #define SHOW(name, var, adjust) static ssize_t \
 275 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 276 { \
 277         struct ads7846 *ts = dev_get_drvdata(dev); \
 278         ssize_t v = ads7846_read12_ser(dev, \
 279                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 280         if (v < 0) \
 281                 return v; \
 282         return sprintf(buf, "%u\n", adjust(ts, v)); \
 283 } \
 284 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 285
 286
 287 /* Sysfs conventions report temperatures in millidegrees Celcius.
 288  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 289  * accuracy scheme without calibration data.  For now we won't try either;
 290  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 291  */
 292 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 293 {
 294         return v;
 295 }
 296
 297 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 298 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 299
 300
 301 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 302  * if we know vREF.  userspace may need to scale vAUX to match the board's
 303  * external resistors; we assume that vBATT only uses the internal ones.
 304  */
 305 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 306 {
 307         unsigned retval = v;
 308
 309         /* external resistors may scale vAUX into 0..vREF */
 310         retval *= ts->vref_mv;
 311         retval = retval >> 12;
 312         return retval;
 313 }
 314
 315 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 316 {
 317         unsigned retval = vaux_adjust(ts, v);
 318
 319         /* ads7846 has a resistor ladder to scale this signal down */
 320         if (ts->model == 7846)
 321                 retval *= 4;
 322         return retval;
 323 }
 324
 325 SHOW(in0_input, vaux, vaux_adjust)
 326 SHOW(in1_input, vbatt, vbatt_adjust)
 327
 328
 329 static struct attribute *ads7846_attributes[] = {
 330         &dev_attr_temp0.attr,
 331         &dev_attr_temp1.attr,
 332         &dev_attr_in0_input.attr,
 333         &dev_attr_in1_input.attr,
 334         NULL,
 335 };
 336
 337 static struct attribute_group ads7846_attr_group = {
 338         .attrs = ads7846_attributes,
 339 };
 340
 341 static struct attribute *ads7843_attributes[] = {
 342         &dev_attr_in0_input.attr,
 343         &dev_attr_in1_input.attr,
 344         NULL,
 345 };
 346
 347 static struct attribute_group ads7843_attr_group = {
 348         .attrs = ads7843_attributes,
 349 };
 350
 351 static struct attribute *ads7845_attributes[] = {
 352         &dev_attr_in0_input.attr,
 353         NULL,
 354 };
 355
 356 static struct attribute_group ads7845_attr_group = {
 357         .attrs = ads7845_attributes,
 358 };
 359
 360 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 361 {
 362         struct device *hwmon;
 363         int err;
 364
 365         /* hwmon sensors need a reference voltage */
 366         switch (ts->model) {
 367         case 7846:
 368                 if (!ts->vref_mv) {
 369                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 370                         ts->vref_mv = 2500;
 371                 }
 372                 break;
 373         case 7845:
 374         case 7843:
 375                 if (!ts->vref_mv) {
 376                         dev_warn(&spi->dev,
 377                                 "external vREF for ADS%d not specified\n",
 378                                 ts->model);
 379                         return 0;
 380                 }
 381                 break;
 382         }
 383
 384         /* different chips have different sensor groups */
 385         switch (ts->model) {
 386         case 7846:
 387                 ts->attr_group = &ads7846_attr_group;
 388                 break;
 389         case 7845:
 390                 ts->attr_group = &ads7845_attr_group;
 391                 break;
 392         case 7843:
 393                 ts->attr_group = &ads7843_attr_group;
 394                 break;
 395         default:
 396                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 397                 return 0;
 398         }
 399
 400         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 401         if (err)
 402                 return err;
 403
 404         hwmon = hwmon_device_register(&spi->dev);
 405         if (IS_ERR(hwmon)) {
 406                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 407                 return PTR_ERR(hwmon);
 408         }
 409
 410         ts->hwmon = hwmon;
 411         return 0;
 412 }
 413
 414 static void ads784x_hwmon_unregister(struct spi_device *spi,
 415                                      struct ads7846 *ts)
 416 {
 417         if (ts->hwmon) {
 418                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 419                 hwmon_device_unregister(ts->hwmon);
 420         }
 421 }
 422
 423 #else
 424 static inline int ads784x_hwmon_register(struct spi_device *spi,
 425                                          struct ads7846 *ts)
 426 {
 427         return 0;
 428 }
 429
 430 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 431                                             struct ads7846 *ts)
 432 {
 433 }
 434 #endif
 435
 436 static int is_pen_down(struct device *dev)
 437 {
 438         struct ads7846  *ts = dev_get_drvdata(dev);
 439
 440         return ts->pendown;
 441 }
 442
 443 static ssize_t ads7846_pen_down_show(struct device *dev,
 444                                      struct device_attribute *attr, char *buf)
 445 {
 446         return sprintf(buf, "%u\n", is_pen_down(dev));
 447 }
 448
 449 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 450
 451 static ssize_t ads7846_disable_show(struct device *dev,
 452                                      struct device_attribute *attr, char *buf)
 453 {
 454         struct ads7846  *ts = dev_get_drvdata(dev);
 455
 456         return sprintf(buf, "%u\n", ts->disabled);
 457 }
 458
 459 static ssize_t ads7846_disable_store(struct device *dev,
 460                                      struct device_attribute *attr,
 461                                      const char *buf, size_t count)
 462 {
 463         struct ads7846 *ts = dev_get_drvdata(dev);
 464         char *endp;
 465         int i;
 466
 467         i = simple_strtoul(buf, &endp, 10);
 468         spin_lock_irq(&ts->lock);
 469
 470         if (i)
 471                 ads7846_disable(ts);
 472         else
 473                 ads7846_enable(ts);
 474
 475         spin_unlock_irq(&ts->lock);
 476
 477         return count;
 478 }
 479
 480 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 481
 482 static struct attribute *ads784x_attributes[] = {
 483         &dev_attr_pen_down.attr,
 484         &dev_attr_disable.attr,
 485         NULL,
 486 };
 487
 488 static struct attribute_group ads784x_attr_group = {
 489         .attrs = ads784x_attributes,
 490 };
 491
 492 /*--------------------------------------------------------------------------*/
 493
 494 /*
 495  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 496  * to retrieve touchscreen status.
 497  *
 498  * The SPI transfer completion callback does the real work.  It reports
 499  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 500  */
 501
 502 static void ads7846_rx(void *ads)
 503 {
 504         struct ads7846          *ts = ads;
 505         unsigned                Rt;
 506         u16                     x, y, z1, z2;
 507
 508         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 509          * on-the-wire format as part of debouncing to get stable readings.
 510          */
 511         x = ts->tc.x;
 512         y = ts->tc.y;
 513         z1 = ts->tc.z1;
 514         z2 = ts->tc.z2;
 515
 516         /* range filtering */
 517         if (x == MAX_12BIT)
 518                 x = 0;
 519
 520         if (ts->model == 7843) {
 521                 Rt = ts->pressure_max / 2;
 522         } else if (likely(x && z1)) {
 523                 /* compute touch pressure resistance using equation #2 */
 524                 Rt = z2;
 525                 Rt -= z1;
 526                 Rt *= x;
 527                 Rt *= ts->x_plate_ohms;
 528                 Rt /= z1;
 529                 Rt = (Rt + 2047) >> 12;
 530         } else {
 531                 Rt = 0;
 532         }
 533
 534         /* Sample found inconsistent by debouncing or pressure is beyond
 535          * the maximum. Don't report it to user space, repeat at least
 536          * once more the measurement
 537          */
 538         if (ts->tc.ignore || Rt > ts->pressure_max) {
 539 #ifdef VERBOSE
 540                 pr_debug("%s: ignored %d pressure %d\n",
 541                         ts->spi->dev.bus_id, ts->tc.ignore, Rt);
 542 #endif
 543                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 544                               HRTIMER_MODE_REL);
 545                 return;
 546         }
 547
 548         /* Maybe check the pendown state before reporting. This discards
 549          * false readings when the pen is lifted.
 550          */
 551         if (ts->penirq_recheck_delay_usecs) {
 552                 udelay(ts->penirq_recheck_delay_usecs);
 553                 if (!ts->get_pendown_state())
 554                         Rt = 0;
 555         }
 556
 557         /* NOTE: We can't rely on the pressure to determine the pen down
 558          * state, even this controller has a pressure sensor.  The pressure
 559          * value can fluctuate for quite a while after lifting the pen and
 560          * in some cases may not even settle at the expected value.
 561          *
 562          * The only safe way to check for the pen up condition is in the
 563          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 564          */
 565         if (Rt) {
 566                 struct input_dev *input = ts->input;
 567
 568                 if (!ts->pendown) {
 569                         input_report_key(input, BTN_TOUCH, 1);
 570                         ts->pendown = 1;
 571 #ifdef VERBOSE
 572                         dev_dbg(&ts->spi->dev, "DOWN\n");
 573 #endif
 574                 }
 575                 input_report_abs(input, ABS_X, x);
 576                 input_report_abs(input, ABS_Y, y);
 577                 input_report_abs(input, ABS_PRESSURE, Rt);
 578
 579                 input_sync(input);
 580 #ifdef VERBOSE
 581                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 582 #endif
 583         }
 584
 585         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 586                         HRTIMER_MODE_REL);
 587 }
 588
 589 static int ads7846_debounce(void *ads, int data_idx, int *val)
 590 {
 591         struct ads7846          *ts = ads;
 592
 593         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 594                 /* Start over collecting consistent readings. */
 595                 ts->read_rep = 0;
 596                 /* Repeat it, if this was the first read or the read
 597                  * wasn't consistent enough. */
 598                 if (ts->read_cnt < ts->debounce_max) {
 599                         ts->last_read = *val;
 600                         ts->read_cnt++;
 601                         return ADS7846_FILTER_REPEAT;
 602                 } else {
 603                         /* Maximum number of debouncing reached and still
 604                          * not enough number of consistent readings. Abort
 605                          * the whole sample, repeat it in the next sampling
 606                          * period.
 607                          */
 608                         ts->read_cnt = 0;
 609                         return ADS7846_FILTER_IGNORE;
 610                 }
 611         } else {
 612                 if (++ts->read_rep > ts->debounce_rep) {
 613                         /* Got a good reading for this coordinate,
 614                          * go for the next one. */
 615                         ts->read_cnt = 0;
 616                         ts->read_rep = 0;
 617                         return ADS7846_FILTER_OK;
 618                 } else {
 619                         /* Read more values that are consistent. */
 620                         ts->read_cnt++;
 621                         return ADS7846_FILTER_REPEAT;
 622                 }
 623         }
 624 }
 625
 626 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 627 {
 628         return ADS7846_FILTER_OK;
 629 }
 630
 631 static void ads7846_rx_val(void *ads)
 632 {
 633         struct ads7846 *ts = ads;
 634         struct spi_message *m;
 635         struct spi_transfer *t;
 636         int val;
 637         int action;
 638         int status;
 639
 640         m = &ts->msg[ts->msg_idx];
 641         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 642
 643         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 644          * built from two 8 bit values written msb-first.
 645          */
 646         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 647
 648         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 649         switch (action) {
 650         case ADS7846_FILTER_REPEAT:
 651                 break;
 652         case ADS7846_FILTER_IGNORE:
 653                 ts->tc.ignore = 1;
 654                 /* Last message will contain ads7846_rx() as the
 655                  * completion function.
 656                  */
 657                 m = ts->last_msg;
 658                 break;
 659         case ADS7846_FILTER_OK:
 660                 *(u16 *)t->rx_buf = val;
 661                 ts->tc.ignore = 0;
 662                 m = &ts->msg[++ts->msg_idx];
 663                 break;
 664         default:
 665                 BUG();
 666         }
 667         status = spi_async(ts->spi, m);
 668         if (status)
 669                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 670                                 status);
 671 }
 672
 673 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 674 {
 675         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 676         int             status = 0;
 677
 678         spin_lock_irq(&ts->lock);
 679
 680         if (unlikely(!ts->get_pendown_state() ||
 681                      device_suspended(&ts->spi->dev))) {
 682                 if (ts->pendown) {
 683                         struct input_dev *input = ts->input;
 684
 685                         input_report_key(input, BTN_TOUCH, 0);
 686                         input_report_abs(input, ABS_PRESSURE, 0);
 687                         input_sync(input);
 688
 689                         ts->pendown = 0;
 690 #ifdef VERBOSE
 691                         dev_dbg(&ts->spi->dev, "UP\n");
 692 #endif
 693                 }
 694
 695                 /* measurement cycle ended */
 696                 if (!device_suspended(&ts->spi->dev)) {
 697                         ts->irq_disabled = 0;
 698                         enable_irq(ts->spi->irq);
 699                 }
 700                 ts->pending = 0;
 701         } else {
 702                 /* pen is still down, continue with the measurement */
 703                 ts->msg_idx = 0;
 704                 status = spi_async(ts->spi, &ts->msg[0]);
 705                 if (status)
 706                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 707         }
 708
 709         spin_unlock_irq(&ts->lock);
 710         return HRTIMER_NORESTART;
 711 }
 712
 713 static irqreturn_t ads7846_irq(int irq, void *handle)
 714 {
 715         struct ads7846 *ts = handle;
 716         unsigned long flags;
 717
 718         spin_lock_irqsave(&ts->lock, flags);
 719         if (likely(ts->get_pendown_state())) {
 720                 if (!ts->irq_disabled) {
 721                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 722                          * like the other dispatchers:  it will report IRQs
 723                          * even after they've been disabled.  We work around
 724                          * that here.  (The "generic irq" framework may help...)
 725                          */
 726                         ts->irq_disabled = 1;
 727                         disable_irq(ts->spi->irq);
 728                         ts->pending = 1;
 729                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 730                                         HRTIMER_MODE_REL);
 731                 }
 732         }
 733         spin_unlock_irqrestore(&ts->lock, flags);
 734
 735         return IRQ_HANDLED;
 736 }
 737
 738 /*--------------------------------------------------------------------------*/
 739
 740 /* Must be called with ts->lock held */
 741 static void ads7846_disable(struct ads7846 *ts)
 742 {
 743         if (ts->disabled)
 744                 return;
 745
 746         ts->disabled = 1;
 747
 748         /* are we waiting for IRQ, or polling? */
 749         if (!ts->pending) {
 750                 ts->irq_disabled = 1;
 751                 disable_irq(ts->spi->irq);
 752         } else {
 753                 /* the timer will run at least once more, and
 754                  * leave everything in a clean state, IRQ disabled
 755                  */
 756                 while (ts->pending) {
 757                         spin_unlock_irq(&ts->lock);
 758                         msleep(1);
 759                         spin_lock_irq(&ts->lock);
 760                 }
 761         }
 762
 763         /* we know the chip's in lowpower mode since we always
 764          * leave it that way after every request
 765          */
 766
 767 }
 768
 769 /* Must be called with ts->lock held */
 770 static void ads7846_enable(struct ads7846 *ts)
 771 {
 772         if (!ts->disabled)
 773                 return;
 774
 775         ts->disabled = 0;
 776         ts->irq_disabled = 0;
 777         enable_irq(ts->spi->irq);
 778 }
 779
 780 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 781 {
 782         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 783
 784         spin_lock_irq(&ts->lock);
 785
 786         ts->is_suspended = 1;
 787         ads7846_disable(ts);
 788
 789         spin_unlock_irq(&ts->lock);
 790
 791         return 0;
 792
 793 }
 794
 795 static int ads7846_resume(struct spi_device *spi)
 796 {
 797         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 798
 799         spin_lock_irq(&ts->lock);
 800
 801         ts->is_suspended = 0;
 802         ads7846_enable(ts);
 803
 804         spin_unlock_irq(&ts->lock);
 805
 806         return 0;
 807 }
 808
 809 static int __devinit ads7846_probe(struct spi_device *spi)
 810 {
 811         struct ads7846                  *ts;
 812         struct input_dev                *input_dev;
 813         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 814         struct spi_message              *m;
 815         struct spi_transfer             *x;
 816         int                             vref;
 817         int                             err;
 818
 819         if (!spi->irq) {
 820                 dev_dbg(&spi->dev, "no IRQ?\n");
 821                 return -ENODEV;
 822         }
 823
 824         if (!pdata) {
 825                 dev_dbg(&spi->dev, "no platform data?\n");
 826                 return -ENODEV;
 827         }
 828
 829         /* don't exceed max specified sample rate */
 830         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 831                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 832                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 833                 return -EINVAL;
 834         }
 835
 836         /* REVISIT when the irq can be triggered active-low, or if for some
 837          * reason the touchscreen isn't hooked up, we don't need to access
 838          * the pendown state.
 839          */
 840         if (pdata->get_pendown_state == NULL) {
 841                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 842                 return -EINVAL;
 843         }
 844
 845         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 846          * that even if the hardware can do that, the SPI controller driver
 847          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 848          */
 849         spi->bits_per_word = 8;
 850         spi->mode = SPI_MODE_0;
 851         err = spi_setup(spi);
 852         if (err < 0)
 853                 return err;
 854
 855         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 856         input_dev = input_allocate_device();
 857         if (!ts || !input_dev) {
 858                 err = -ENOMEM;
 859                 goto err_free_mem;
 860         }
 861
 862         dev_set_drvdata(&spi->dev, ts);
 863
 864         ts->spi = spi;
 865         ts->input = input_dev;
 866         ts->vref_mv = pdata->vref_mv;
 867
 868         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 869         ts->timer.function = ads7846_timer;
 870
 871         spin_lock_init(&ts->lock);
 872
 873         ts->model = pdata->model ? : 7846;
 874         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 875         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 876         ts->pressure_max = pdata->pressure_max ? : ~0;
 877
 878         if (pdata->filter != NULL) {
 879                 if (pdata->filter_init != NULL) {
 880                         err = pdata->filter_init(pdata, &ts->filter_data);
 881                         if (err < 0)
 882                                 goto err_free_mem;
 883                 }
 884                 ts->filter = pdata->filter;
 885                 ts->filter_cleanup = pdata->filter_cleanup;
 886         } else if (pdata->debounce_max) {
 887                 ts->debounce_max = pdata->debounce_max;
 888                 if (ts->debounce_max < 2)
 889                         ts->debounce_max = 2;
 890                 ts->debounce_tol = pdata->debounce_tol;
 891                 ts->debounce_rep = pdata->debounce_rep;
 892                 ts->filter = ads7846_debounce;
 893                 ts->filter_data = ts;
 894         } else
 895                 ts->filter = ads7846_no_filter;
 896         ts->get_pendown_state = pdata->get_pendown_state;
 897
 898         if (pdata->penirq_recheck_delay_usecs)
 899                 ts->penirq_recheck_delay_usecs =
 900                                 pdata->penirq_recheck_delay_usecs;
 901
 902         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 903
 904         input_dev->name = "ADS784x Touchscreen";
 905         input_dev->phys = ts->phys;
 906         input_dev->dev.parent = &spi->dev;
 907
 908         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 909         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 910         input_set_abs_params(input_dev, ABS_X,
 911                         pdata->x_min ? : 0,
 912                         pdata->x_max ? : MAX_12BIT,
 913                         0, 0);
 914         input_set_abs_params(input_dev, ABS_Y,
 915                         pdata->y_min ? : 0,
 916                         pdata->y_max ? : MAX_12BIT,
 917                         0, 0);
 918         input_set_abs_params(input_dev, ABS_PRESSURE,
 919                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 920
 921         vref = pdata->keep_vref_on;
 922
 923         /* set up the transfers to read touchscreen state; this assumes we
 924          * use formula #2 for pressure, not #3.
 925          */
 926         m = &ts->msg[0];
 927         x = ts->xfer;
 928
 929         spi_message_init(m);
 930
 931         /* y- still on; turn on only y+ (and ADC) */
 932         ts->read_y = READ_Y(vref);
 933         x->tx_buf = &ts->read_y;
 934         x->len = 1;
 935         spi_message_add_tail(x, m);
 936
 937         x++;
 938         x->rx_buf = &ts->tc.y;
 939         x->len = 2;
 940         spi_message_add_tail(x, m);
 941
 942         /* the first sample after switching drivers can be low quality;
 943          * optionally discard it, using a second one after the signals
 944          * have had enough time to stabilize.
 945          */
 946         if (pdata->settle_delay_usecs) {
 947                 x->delay_usecs = pdata->settle_delay_usecs;
 948
 949                 x++;
 950                 x->tx_buf = &ts->read_y;
 951                 x->len = 1;
 952                 spi_message_add_tail(x, m);
 953
 954                 x++;
 955                 x->rx_buf = &ts->tc.y;
 956                 x->len = 2;
 957                 spi_message_add_tail(x, m);
 958         }
 959
 960         m->complete = ads7846_rx_val;
 961         m->context = ts;
 962
 963         m++;
 964         spi_message_init(m);
 965
 966         /* turn y- off, x+ on, then leave in lowpower */
 967         x++;
 968         ts->read_x = READ_X(vref);
 969         x->tx_buf = &ts->read_x;
 970         x->len = 1;
 971         spi_message_add_tail(x, m);
 972
 973         x++;
 974         x->rx_buf = &ts->tc.x;
 975         x->len = 2;
 976         spi_message_add_tail(x, m);
 977
 978         /* ... maybe discard first sample ... */
 979         if (pdata->settle_delay_usecs) {
 980                 x->delay_usecs = pdata->settle_delay_usecs;
 981
 982                 x++;
 983                 x->tx_buf = &ts->read_x;
 984                 x->len = 1;
 985                 spi_message_add_tail(x, m);
 986
 987                 x++;
 988                 x->rx_buf = &ts->tc.x;
 989                 x->len = 2;
 990                 spi_message_add_tail(x, m);
 991         }
 992
 993         m->complete = ads7846_rx_val;
 994         m->context = ts;
 995
 996         /* turn y+ off, x- on; we'll use formula #2 */
 997         if (ts->model == 7846) {
 998                 m++;
 999                 spi_message_init(m);
1000
1001                 x++;
1002                 ts->read_z1 = READ_Z1(vref);
1003                 x->tx_buf = &ts->read_z1;
1004                 x->len = 1;
1005                 spi_message_add_tail(x, m);
1006
1007                 x++;
1008                 x->rx_buf = &ts->tc.z1;
1009                 x->len = 2;
1010                 spi_message_add_tail(x, m);
1011
1012                 /* ... maybe discard first sample ... */
1013                 if (pdata->settle_delay_usecs) {
1014                         x->delay_usecs = pdata->settle_delay_usecs;
1015
1016                         x++;
1017                         x->tx_buf = &ts->read_z1;
1018                         x->len = 1;
1019                         spi_message_add_tail(x, m);
1020
1021                         x++;
1022                         x->rx_buf = &ts->tc.z1;
1023                         x->len = 2;
1024                         spi_message_add_tail(x, m);
1025                 }
1026
1027                 m->complete = ads7846_rx_val;
1028                 m->context = ts;
1029
1030                 m++;
1031                 spi_message_init(m);
1032
1033                 x++;
1034                 ts->read_z2 = READ_Z2(vref);
1035                 x->tx_buf = &ts->read_z2;
1036                 x->len = 1;
1037                 spi_message_add_tail(x, m);
1038
1039                 x++;
1040                 x->rx_buf = &ts->tc.z2;
1041                 x->len = 2;
1042                 spi_message_add_tail(x, m);
1043
1044                 /* ... maybe discard first sample ... */
1045                 if (pdata->settle_delay_usecs) {
1046                         x->delay_usecs = pdata->settle_delay_usecs;
1047
1048                         x++;
1049                         x->tx_buf = &ts->read_z2;
1050                         x->len = 1;
1051                         spi_message_add_tail(x, m);
1052
1053                         x++;
1054                         x->rx_buf = &ts->tc.z2;
1055                         x->len = 2;
1056                         spi_message_add_tail(x, m);
1057                 }
1058
1059                 m->complete = ads7846_rx_val;
1060                 m->context = ts;
1061         }
1062
1063         /* power down */
1064         m++;
1065         spi_message_init(m);
1066
1067         x++;
1068         ts->pwrdown = PWRDOWN;
1069         x->tx_buf = &ts->pwrdown;
1070         x->len = 1;
1071         spi_message_add_tail(x, m);
1072
1073         x++;
1074         x->rx_buf = &ts->dummy;
1075         x->len = 2;
1076         CS_CHANGE(*x);
1077         spi_message_add_tail(x, m);
1078
1079         m->complete = ads7846_rx;
1080         m->context = ts;
1081
1082         ts->last_msg = m;
1083
1084         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1085                         spi->dev.driver->name, ts)) {
1086                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1087                 err = -EBUSY;
1088                 goto err_cleanup_filter;
1089         }
1090
1091         err = ads784x_hwmon_register(spi, ts);
1092         if (err)
1093                 goto err_free_irq;
1094
1095         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1096
1097         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1098          * the touchscreen, in case it's not connected.
1099          */
1100         (void) ads7846_read12_ser(&spi->dev,
1101                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1102
1103         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1104         if (err)
1105                 goto err_remove_hwmon;
1106
1107         err = input_register_device(input_dev);
1108         if (err)
1109                 goto err_remove_attr_group;
1110
1111         return 0;
1112
1113  err_remove_attr_group:
1114         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1115  err_remove_hwmon:
1116         ads784x_hwmon_unregister(spi, ts);
1117  err_free_irq:
1118         free_irq(spi->irq, ts);
1119  err_cleanup_filter:
1120         if (ts->filter_cleanup)
1121                 ts->filter_cleanup(ts->filter_data);
1122  err_free_mem:
1123         input_free_device(input_dev);
1124         kfree(ts);
1125         return err;
1126 }
1127
1128 static int __devexit ads7846_remove(struct spi_device *spi)
1129 {
1130         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1131
1132         ads784x_hwmon_unregister(spi, ts);
1133         input_unregister_device(ts->input);
1134
1135         ads7846_suspend(spi, PMSG_SUSPEND);
1136
1137         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1138
1139         free_irq(ts->spi->irq, ts);
1140         /* suspend left the IRQ disabled */
1141         enable_irq(ts->spi->irq);
1142
1143         if (ts->filter_cleanup)
1144                 ts->filter_cleanup(ts->filter_data);
1145
1146         kfree(ts);
1147
1148         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1149         return 0;
1150 }
1151
1152 static struct spi_driver ads7846_driver = {
1153         .driver = {
1154                 .name   = "ads7846",
1155                 .bus    = &spi_bus_type,
1156                 .owner  = THIS_MODULE,
1157         },
1158         .probe          = ads7846_probe,
1159         .remove         = __devexit_p(ads7846_remove),
1160         .suspend        = ads7846_suspend,
1161         .resume         = ads7846_resume,
1162 };
1163
1164 static int __init ads7846_init(void)
1165 {
1166         return spi_register_driver(&ads7846_driver);
1167 }
1168 module_init(ads7846_init);
1169
1170 static void __exit ads7846_exit(void)
1171 {
1172         spi_unregister_driver(&ads7846_driver);
1173 }
1174 module_exit(ads7846_exit);
1175
1176 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1177 MODULE_LICENSE("GPL");