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/gpio.h>
  28 #include <linux/spi/spi.h>
  29 #include <linux/spi/ads7846.h>
  30 #include <asm/irq.h>
  31
  32
  33 /*
  34  * This code has been heavily tested on a Nokia 770, and lightly
  35  * tested on other ads7846 devices (OSK/Mistral, Lubbock).
  36  * TSC2046 is just newer ads7846 silicon.
  37  * Support for ads7843 tested on Atmel at91sam926x-EK.
  38  * Support for ads7845 has only been stubbed in.
  39  *
  40  * IRQ handling needs a workaround because of a shortcoming in handling
  41  * edge triggered IRQs on some platforms like the OMAP1/2. These
  42  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  43  * have to maintain our own SW IRQ disabled status. This should be
  44  * removed as soon as the affected platform's IRQ handling is fixed.
  45  *
  46  * app note sbaa036 talks in more detail about accurate sampling...
  47  * that ought to help in situations like LCDs inducing noise (which
  48  * can also be helped by using synch signals) and more generally.
  49  * This driver tries to utilize the measures described in the app
  50  * note. The strength of filtering can be set in the board-* specific
  51  * files.
  52  */
  53
  54 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  55 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  56
  57 /* this driver doesn't aim at the peak continuous sample rate */
  58 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  59
  60 struct ts_event {
  61         /* For portability, we can't read 12 bit values using SPI (which
  62          * would make the controller deliver them as native byteorder u16
  63          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  64          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  65          */
  66         u16     x;
  67         u16     y;
  68         u16     z1, z2;
  69         int     ignore;
  70 };
  71
  72 /*
  73  * We allocate this separately to avoid cache line sharing issues when
  74  * driver is used with DMA-based SPI controllers (like atmel_spi) on
  75  * systems where main memory is not DMA-coherent (most non-x86 boards).
  76  */
  77 struct ads7846_packet {
  78         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  79         u16                     dummy;          /* for the pwrdown read */
  80         struct ts_event         tc;
  81 };
  82
  83 struct ads7846 {
  84         struct input_dev        *input;
  85         char                    phys[32];
  86         char                    name[32];
  87
  88         struct spi_device       *spi;
  89
  90 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  91         struct attribute_group  *attr_group;
  92         struct device           *hwmon;
  93 #endif
  94
  95         u16                     model;
  96         u16                     vref_mv;
  97         u16                     vref_delay_usecs;
  98         u16                     x_plate_ohms;
  99         u16                     pressure_max;
 100
 101         bool                    swap_xy;
 102
 103         struct ads7846_packet   *packet;
 104
 105         struct spi_transfer     xfer[18];
 106         struct spi_message      msg[5];
 107         struct spi_message      *last_msg;
 108         int                     msg_idx;
 109         int                     read_cnt;
 110         int                     read_rep;
 111         int                     last_read;
 112
 113         u16                     debounce_max;
 114         u16                     debounce_tol;
 115         u16                     debounce_rep;
 116
 117         u16                     penirq_recheck_delay_usecs;
 118
 119         spinlock_t              lock;
 120         struct hrtimer          timer;
 121         unsigned                pendown:1;      /* P: lock */
 122         unsigned                pending:1;      /* P: lock */
 123 // FIXME remove "irq_disabled"
 124         unsigned                irq_disabled:1; /* P: lock */
 125         unsigned                disabled:1;
 126         unsigned                is_suspended:1;
 127
 128         int                     (*filter)(void *data, int data_idx, int *val);
 129         void                    *filter_data;
 130         void                    (*filter_cleanup)(void *data);
 131         int                     (*get_pendown_state)(void);
 132         int                     gpio_pendown;
 133
 134         void                    (*wait_for_sync)(void);
 135 };
 136
 137 /* leave chip selected when we're done, for quicker re-select? */
 138 #if     0
 139 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 140 #else
 141 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 142 #endif
 143
 144 /*--------------------------------------------------------------------------*/
 145
 146 /* The ADS7846 has touchscreen and other sensors.
 147  * Earlier ads784x chips are somewhat compatible.
 148  */
 149 #define ADS_START               (1 << 7)
 150 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 151 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 152 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 153 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 154 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 155 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 156 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 157 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 158 #define ADS_8_BIT               (1 << 3)
 159 #define ADS_12_BIT              (0 << 3)
 160 #define ADS_SER                 (1 << 2)        /* non-differential */
 161 #define ADS_DFR                 (0 << 2)        /* differential */
 162 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 163 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 164 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 165 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 166
 167 #define MAX_12BIT       ((1<<12)-1)
 168
 169 /* leave ADC powered up (disables penirq) between differential samples */
 170 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 171         | ADS_12_BIT | ADS_DFR | \
 172         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 173
 174 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 175 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 176 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 177
 178 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 179 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 180
 181 /* single-ended samples need to first power up reference voltage;
 182  * we leave both ADC and VREF powered
 183  */
 184 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 185         | ADS_12_BIT | ADS_SER)
 186
 187 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 188 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 189
 190 /*--------------------------------------------------------------------------*/
 191
 192 /*
 193  * Non-touchscreen sensors only use single-ended conversions.
 194  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 195  * ads7846 lets that pin be unconnected, to use internal vREF.
 196  */
 197
 198 struct ser_req {
 199         u8                      ref_on;
 200         u8                      command;
 201         u8                      ref_off;
 202         u16                     scratch;
 203         __be16                  sample;
 204         struct spi_message      msg;
 205         struct spi_transfer     xfer[6];
 206 };
 207
 208 static void ads7846_enable(struct ads7846 *ts);
 209 static void ads7846_disable(struct ads7846 *ts);
 210
 211 static int device_suspended(struct device *dev)
 212 {
 213         struct ads7846 *ts = dev_get_drvdata(dev);
 214         return ts->is_suspended || ts->disabled;
 215 }
 216
 217 static int ads7846_read12_ser(struct device *dev, unsigned command)
 218 {
 219         struct spi_device       *spi = to_spi_device(dev);
 220         struct ads7846          *ts = dev_get_drvdata(dev);
 221         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 222         int                     status;
 223         int                     use_internal;
 224
 225         if (!req)
 226                 return -ENOMEM;
 227
 228         spi_message_init(&req->msg);
 229
 230         /* FIXME boards with ads7846 might use external vref instead ... */
 231         use_internal = (ts->model == 7846);
 232
 233         /* maybe turn on internal vREF, and let it settle */
 234         if (use_internal) {
 235                 req->ref_on = REF_ON;
 236                 req->xfer[0].tx_buf = &req->ref_on;
 237                 req->xfer[0].len = 1;
 238                 spi_message_add_tail(&req->xfer[0], &req->msg);
 239
 240                 req->xfer[1].rx_buf = &req->scratch;
 241                 req->xfer[1].len = 2;
 242
 243                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 244                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 245                 spi_message_add_tail(&req->xfer[1], &req->msg);
 246         }
 247
 248         /* take sample */
 249         req->command = (u8) command;
 250         req->xfer[2].tx_buf = &req->command;
 251         req->xfer[2].len = 1;
 252         spi_message_add_tail(&req->xfer[2], &req->msg);
 253
 254         req->xfer[3].rx_buf = &req->sample;
 255         req->xfer[3].len = 2;
 256         spi_message_add_tail(&req->xfer[3], &req->msg);
 257
 258         /* REVISIT:  take a few more samples, and compare ... */
 259
 260         /* converter in low power mode & enable PENIRQ */
 261         req->ref_off = PWRDOWN;
 262         req->xfer[4].tx_buf = &req->ref_off;
 263         req->xfer[4].len = 1;
 264         spi_message_add_tail(&req->xfer[4], &req->msg);
 265
 266         req->xfer[5].rx_buf = &req->scratch;
 267         req->xfer[5].len = 2;
 268         CS_CHANGE(req->xfer[5]);
 269         spi_message_add_tail(&req->xfer[5], &req->msg);
 270
 271         ts->irq_disabled = 1;
 272         disable_irq(spi->irq);
 273         status = spi_sync(spi, &req->msg);
 274         ts->irq_disabled = 0;
 275         enable_irq(spi->irq);
 276
 277         if (status == 0) {
 278                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 279                 status = be16_to_cpu(req->sample);
 280                 status = status >> 3;
 281                 status &= 0x0fff;
 282         }
 283
 284         kfree(req);
 285         return status;
 286 }
 287
 288 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 289
 290 #define SHOW(name, var, adjust) static ssize_t \
 291 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 292 { \
 293         struct ads7846 *ts = dev_get_drvdata(dev); \
 294         ssize_t v = ads7846_read12_ser(dev, \
 295                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 296         if (v < 0) \
 297                 return v; \
 298         return sprintf(buf, "%u\n", adjust(ts, v)); \
 299 } \
 300 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 301
 302
 303 /* Sysfs conventions report temperatures in millidegrees Celsius.
 304  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 305  * accuracy scheme without calibration data.  For now we won't try either;
 306  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 307  */
 308 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 309 {
 310         return v;
 311 }
 312
 313 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 314 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 315
 316
 317 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 318  * if we know vREF.  userspace may need to scale vAUX to match the board's
 319  * external resistors; we assume that vBATT only uses the internal ones.
 320  */
 321 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 322 {
 323         unsigned retval = v;
 324
 325         /* external resistors may scale vAUX into 0..vREF */
 326         retval *= ts->vref_mv;
 327         retval = retval >> 12;
 328         return retval;
 329 }
 330
 331 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 332 {
 333         unsigned retval = vaux_adjust(ts, v);
 334
 335         /* ads7846 has a resistor ladder to scale this signal down */
 336         if (ts->model == 7846)
 337                 retval *= 4;
 338         return retval;
 339 }
 340
 341 SHOW(in0_input, vaux, vaux_adjust)
 342 SHOW(in1_input, vbatt, vbatt_adjust)
 343
 344
 345 static struct attribute *ads7846_attributes[] = {
 346         &dev_attr_temp0.attr,
 347         &dev_attr_temp1.attr,
 348         &dev_attr_in0_input.attr,
 349         &dev_attr_in1_input.attr,
 350         NULL,
 351 };
 352
 353 static struct attribute_group ads7846_attr_group = {
 354         .attrs = ads7846_attributes,
 355 };
 356
 357 static struct attribute *ads7843_attributes[] = {
 358         &dev_attr_in0_input.attr,
 359         &dev_attr_in1_input.attr,
 360         NULL,
 361 };
 362
 363 static struct attribute_group ads7843_attr_group = {
 364         .attrs = ads7843_attributes,
 365 };
 366
 367 static struct attribute *ads7845_attributes[] = {
 368         &dev_attr_in0_input.attr,
 369         NULL,
 370 };
 371
 372 static struct attribute_group ads7845_attr_group = {
 373         .attrs = ads7845_attributes,
 374 };
 375
 376 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 377 {
 378         struct device *hwmon;
 379         int err;
 380
 381         /* hwmon sensors need a reference voltage */
 382         switch (ts->model) {
 383         case 7846:
 384                 if (!ts->vref_mv) {
 385                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 386                         ts->vref_mv = 2500;
 387                 }
 388                 break;
 389         case 7845:
 390         case 7843:
 391                 if (!ts->vref_mv) {
 392                         dev_warn(&spi->dev,
 393                                 "external vREF for ADS%d not specified\n",
 394                                 ts->model);
 395                         return 0;
 396                 }
 397                 break;
 398         }
 399
 400         /* different chips have different sensor groups */
 401         switch (ts->model) {
 402         case 7846:
 403                 ts->attr_group = &ads7846_attr_group;
 404                 break;
 405         case 7845:
 406                 ts->attr_group = &ads7845_attr_group;
 407                 break;
 408         case 7843:
 409                 ts->attr_group = &ads7843_attr_group;
 410                 break;
 411         default:
 412                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 413                 return 0;
 414         }
 415
 416         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 417         if (err)
 418                 return err;
 419
 420         hwmon = hwmon_device_register(&spi->dev);
 421         if (IS_ERR(hwmon)) {
 422                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 423                 return PTR_ERR(hwmon);
 424         }
 425
 426         ts->hwmon = hwmon;
 427         return 0;
 428 }
 429
 430 static void ads784x_hwmon_unregister(struct spi_device *spi,
 431                                      struct ads7846 *ts)
 432 {
 433         if (ts->hwmon) {
 434                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 435                 hwmon_device_unregister(ts->hwmon);
 436         }
 437 }
 438
 439 #else
 440 static inline int ads784x_hwmon_register(struct spi_device *spi,
 441                                          struct ads7846 *ts)
 442 {
 443         return 0;
 444 }
 445
 446 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 447                                             struct ads7846 *ts)
 448 {
 449 }
 450 #endif
 451
 452 static int is_pen_down(struct device *dev)
 453 {
 454         struct ads7846  *ts = dev_get_drvdata(dev);
 455
 456         return ts->pendown;
 457 }
 458
 459 static ssize_t ads7846_pen_down_show(struct device *dev,
 460                                      struct device_attribute *attr, char *buf)
 461 {
 462         return sprintf(buf, "%u\n", is_pen_down(dev));
 463 }
 464
 465 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 466
 467 static ssize_t ads7846_disable_show(struct device *dev,
 468                                      struct device_attribute *attr, char *buf)
 469 {
 470         struct ads7846  *ts = dev_get_drvdata(dev);
 471
 472         return sprintf(buf, "%u\n", ts->disabled);
 473 }
 474
 475 static ssize_t ads7846_disable_store(struct device *dev,
 476                                      struct device_attribute *attr,
 477                                      const char *buf, size_t count)
 478 {
 479         struct ads7846 *ts = dev_get_drvdata(dev);
 480         unsigned long i;
 481
 482         if (strict_strtoul(buf, 10, &i))
 483                 return -EINVAL;
 484
 485         spin_lock_irq(&ts->lock);
 486
 487         if (i)
 488                 ads7846_disable(ts);
 489         else
 490                 ads7846_enable(ts);
 491
 492         spin_unlock_irq(&ts->lock);
 493
 494         return count;
 495 }
 496
 497 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 498
 499 static struct attribute *ads784x_attributes[] = {
 500         &dev_attr_pen_down.attr,
 501         &dev_attr_disable.attr,
 502         NULL,
 503 };
 504
 505 static struct attribute_group ads784x_attr_group = {
 506         .attrs = ads784x_attributes,
 507 };
 508
 509 /*--------------------------------------------------------------------------*/
 510
 511 static int get_pendown_state(struct ads7846 *ts)
 512 {
 513         if (ts->get_pendown_state)
 514                 return ts->get_pendown_state();
 515
 516         return !gpio_get_value(ts->gpio_pendown);
 517 }
 518
 519 static void null_wait_for_sync(void)
 520 {
 521 }
 522
 523 /*
 524  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 525  * to retrieve touchscreen status.
 526  *
 527  * The SPI transfer completion callback does the real work.  It reports
 528  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 529  */
 530
 531 static void ads7846_rx(void *ads)
 532 {
 533         struct ads7846          *ts = ads;
 534         struct ads7846_packet   *packet = ts->packet;
 535         unsigned                Rt;
 536         u16                     x, y, z1, z2;
 537
 538         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 539          * on-the-wire format as part of debouncing to get stable readings.
 540          */
 541         x = packet->tc.x;
 542         y = packet->tc.y;
 543         z1 = packet->tc.z1;
 544         z2 = packet->tc.z2;
 545
 546         /* range filtering */
 547         if (x == MAX_12BIT)
 548                 x = 0;
 549
 550         if (ts->model == 7843) {
 551                 Rt = ts->pressure_max / 2;
 552         } else if (likely(x && z1)) {
 553                 /* compute touch pressure resistance using equation #2 */
 554                 Rt = z2;
 555                 Rt -= z1;
 556                 Rt *= x;
 557                 Rt *= ts->x_plate_ohms;
 558                 Rt /= z1;
 559                 Rt = (Rt + 2047) >> 12;
 560         } else {
 561                 Rt = 0;
 562         }
 563
 564         /* Sample found inconsistent by debouncing or pressure is beyond
 565          * the maximum. Don't report it to user space, repeat at least
 566          * once more the measurement
 567          */
 568         if (packet->tc.ignore || Rt > ts->pressure_max) {
 569 #ifdef VERBOSE
 570                 pr_debug("%s: ignored %d pressure %d\n",
 571                         dev_name(&ts->spi->dev), packet->tc.ignore, Rt);
 572 #endif
 573                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 574                               HRTIMER_MODE_REL);
 575                 return;
 576         }
 577
 578         /* Maybe check the pendown state before reporting. This discards
 579          * false readings when the pen is lifted.
 580          */
 581         if (ts->penirq_recheck_delay_usecs) {
 582                 udelay(ts->penirq_recheck_delay_usecs);
 583                 if (!get_pendown_state(ts))
 584                         Rt = 0;
 585         }
 586
 587         /* NOTE: We can't rely on the pressure to determine the pen down
 588          * state, even this controller has a pressure sensor.  The pressure
 589          * value can fluctuate for quite a while after lifting the pen and
 590          * in some cases may not even settle at the expected value.
 591          *
 592          * The only safe way to check for the pen up condition is in the
 593          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 594          */
 595         if (Rt) {
 596                 struct input_dev *input = ts->input;
 597
 598                 if (!ts->pendown) {
 599                         input_report_key(input, BTN_TOUCH, 1);
 600                         ts->pendown = 1;
 601 #ifdef VERBOSE
 602                         dev_dbg(&ts->spi->dev, "DOWN\n");
 603 #endif
 604                 }
 605
 606                 if (ts->swap_xy)
 607                         swap(x, y);
 608
 609                 input_report_abs(input, ABS_X, x);
 610                 input_report_abs(input, ABS_Y, y);
 611                 input_report_abs(input, ABS_PRESSURE, Rt);
 612
 613                 input_sync(input);
 614 #ifdef VERBOSE
 615                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 616 #endif
 617         }
 618
 619         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 620                         HRTIMER_MODE_REL);
 621 }
 622
 623 static int ads7846_debounce(void *ads, int data_idx, int *val)
 624 {
 625         struct ads7846          *ts = ads;
 626
 627         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 628                 /* Start over collecting consistent readings. */
 629                 ts->read_rep = 0;
 630                 /* Repeat it, if this was the first read or the read
 631                  * wasn't consistent enough. */
 632                 if (ts->read_cnt < ts->debounce_max) {
 633                         ts->last_read = *val;
 634                         ts->read_cnt++;
 635                         return ADS7846_FILTER_REPEAT;
 636                 } else {
 637                         /* Maximum number of debouncing reached and still
 638                          * not enough number of consistent readings. Abort
 639                          * the whole sample, repeat it in the next sampling
 640                          * period.
 641                          */
 642                         ts->read_cnt = 0;
 643                         return ADS7846_FILTER_IGNORE;
 644                 }
 645         } else {
 646                 if (++ts->read_rep > ts->debounce_rep) {
 647                         /* Got a good reading for this coordinate,
 648                          * go for the next one. */
 649                         ts->read_cnt = 0;
 650                         ts->read_rep = 0;
 651                         return ADS7846_FILTER_OK;
 652                 } else {
 653                         /* Read more values that are consistent. */
 654                         ts->read_cnt++;
 655                         return ADS7846_FILTER_REPEAT;
 656                 }
 657         }
 658 }
 659
 660 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 661 {
 662         return ADS7846_FILTER_OK;
 663 }
 664
 665 static void ads7846_rx_val(void *ads)
 666 {
 667         struct ads7846 *ts = ads;
 668         struct ads7846_packet *packet = ts->packet;
 669         struct spi_message *m;
 670         struct spi_transfer *t;
 671         int val;
 672         int action;
 673         int status;
 674
 675         m = &ts->msg[ts->msg_idx];
 676         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 677
 678         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 679          * built from two 8 bit values written msb-first.
 680          */
 681         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 682
 683         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 684         switch (action) {
 685         case ADS7846_FILTER_REPEAT:
 686                 break;
 687         case ADS7846_FILTER_IGNORE:
 688                 packet->tc.ignore = 1;
 689                 /* Last message will contain ads7846_rx() as the
 690                  * completion function.
 691                  */
 692                 m = ts->last_msg;
 693                 break;
 694         case ADS7846_FILTER_OK:
 695                 *(u16 *)t->rx_buf = val;
 696                 packet->tc.ignore = 0;
 697                 m = &ts->msg[++ts->msg_idx];
 698                 break;
 699         default:
 700                 BUG();
 701         }
 702         ts->wait_for_sync();
 703         status = spi_async(ts->spi, m);
 704         if (status)
 705                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 706                                 status);
 707 }
 708
 709 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 710 {
 711         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 712         int             status = 0;
 713
 714         spin_lock(&ts->lock);
 715
 716         if (unlikely(!get_pendown_state(ts) ||
 717                      device_suspended(&ts->spi->dev))) {
 718                 if (ts->pendown) {
 719                         struct input_dev *input = ts->input;
 720
 721                         input_report_key(input, BTN_TOUCH, 0);
 722                         input_report_abs(input, ABS_PRESSURE, 0);
 723                         input_sync(input);
 724
 725                         ts->pendown = 0;
 726 #ifdef VERBOSE
 727                         dev_dbg(&ts->spi->dev, "UP\n");
 728 #endif
 729                 }
 730
 731                 /* measurement cycle ended */
 732                 if (!device_suspended(&ts->spi->dev)) {
 733                         ts->irq_disabled = 0;
 734                         enable_irq(ts->spi->irq);
 735                 }
 736                 ts->pending = 0;
 737         } else {
 738                 /* pen is still down, continue with the measurement */
 739                 ts->msg_idx = 0;
 740                 ts->wait_for_sync();
 741                 status = spi_async(ts->spi, &ts->msg[0]);
 742                 if (status)
 743                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 744         }
 745
 746         spin_unlock(&ts->lock);
 747         return HRTIMER_NORESTART;
 748 }
 749
 750 static irqreturn_t ads7846_irq(int irq, void *handle)
 751 {
 752         struct ads7846 *ts = handle;
 753         unsigned long flags;
 754
 755         spin_lock_irqsave(&ts->lock, flags);
 756         if (likely(get_pendown_state(ts))) {
 757                 if (!ts->irq_disabled) {
 758                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 759                          * like the other dispatchers:  it will report IRQs
 760                          * even after they've been disabled.  We work around
 761                          * that here.  (The "generic irq" framework may help...)
 762                          */
 763                         ts->irq_disabled = 1;
 764                         disable_irq_nosync(ts->spi->irq);
 765                         ts->pending = 1;
 766                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 767                                         HRTIMER_MODE_REL);
 768                 }
 769         }
 770         spin_unlock_irqrestore(&ts->lock, flags);
 771
 772         return IRQ_HANDLED;
 773 }
 774
 775 /*--------------------------------------------------------------------------*/
 776
 777 /* Must be called with ts->lock held */
 778 static void ads7846_disable(struct ads7846 *ts)
 779 {
 780         if (ts->disabled)
 781                 return;
 782
 783         ts->disabled = 1;
 784
 785         /* are we waiting for IRQ, or polling? */
 786         if (!ts->pending) {
 787                 ts->irq_disabled = 1;
 788                 disable_irq(ts->spi->irq);
 789         } else {
 790                 /* the timer will run at least once more, and
 791                  * leave everything in a clean state, IRQ disabled
 792                  */
 793                 while (ts->pending) {
 794                         spin_unlock_irq(&ts->lock);
 795                         msleep(1);
 796                         spin_lock_irq(&ts->lock);
 797                 }
 798         }
 799
 800         /* we know the chip's in lowpower mode since we always
 801          * leave it that way after every request
 802          */
 803 }
 804
 805 /* Must be called with ts->lock held */
 806 static void ads7846_enable(struct ads7846 *ts)
 807 {
 808         if (!ts->disabled)
 809                 return;
 810
 811         ts->disabled = 0;
 812         ts->irq_disabled = 0;
 813         enable_irq(ts->spi->irq);
 814 }
 815
 816 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 817 {
 818         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 819
 820         spin_lock_irq(&ts->lock);
 821
 822         ts->is_suspended = 1;
 823         ads7846_disable(ts);
 824
 825         spin_unlock_irq(&ts->lock);
 826
 827         return 0;
 828
 829 }
 830
 831 static int ads7846_resume(struct spi_device *spi)
 832 {
 833         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 834
 835         spin_lock_irq(&ts->lock);
 836
 837         ts->is_suspended = 0;
 838         ads7846_enable(ts);
 839
 840         spin_unlock_irq(&ts->lock);
 841
 842         return 0;
 843 }
 844
 845 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 846 {
 847         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 848         int err;
 849
 850         /* REVISIT when the irq can be triggered active-low, or if for some
 851          * reason the touchscreen isn't hooked up, we don't need to access
 852          * the pendown state.
 853          */
 854         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
 855                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 856                 return -EINVAL;
 857         }
 858
 859         if (pdata->get_pendown_state) {
 860                 ts->get_pendown_state = pdata->get_pendown_state;
 861                 return 0;
 862         }
 863
 864         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 865         if (err) {
 866                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 867                                 pdata->gpio_pendown);
 868                 return err;
 869         }
 870
 871         ts->gpio_pendown = pdata->gpio_pendown;
 872         return 0;
 873 }
 874
 875 static int __devinit ads7846_probe(struct spi_device *spi)
 876 {
 877         struct ads7846                  *ts;
 878         struct ads7846_packet           *packet;
 879         struct input_dev                *input_dev;
 880         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 881         struct spi_message              *m;
 882         struct spi_transfer             *x;
 883         int                             vref;
 884         int                             err;
 885
 886         if (!spi->irq) {
 887                 dev_dbg(&spi->dev, "no IRQ?\n");
 888                 return -ENODEV;
 889         }
 890
 891         if (!pdata) {
 892                 dev_dbg(&spi->dev, "no platform data?\n");
 893                 return -ENODEV;
 894         }
 895
 896         /* don't exceed max specified sample rate */
 897         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 898                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 899                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 900                 return -EINVAL;
 901         }
 902
 903         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 904          * that even if the hardware can do that, the SPI controller driver
 905          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 906          */
 907         spi->bits_per_word = 8;
 908         spi->mode = SPI_MODE_0;
 909         err = spi_setup(spi);
 910         if (err < 0)
 911                 return err;
 912
 913         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 914         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
 915         input_dev = input_allocate_device();
 916         if (!ts || !packet || !input_dev) {
 917                 err = -ENOMEM;
 918                 goto err_free_mem;
 919         }
 920
 921         dev_set_drvdata(&spi->dev, ts);
 922
 923         ts->packet = packet;
 924         ts->spi = spi;
 925         ts->input = input_dev;
 926         ts->vref_mv = pdata->vref_mv;
 927         ts->swap_xy = pdata->swap_xy;
 928
 929         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 930         ts->timer.function = ads7846_timer;
 931
 932         spin_lock_init(&ts->lock);
 933
 934         ts->model = pdata->model ? : 7846;
 935         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 936         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 937         ts->pressure_max = pdata->pressure_max ? : ~0;
 938
 939         if (pdata->filter != NULL) {
 940                 if (pdata->filter_init != NULL) {
 941                         err = pdata->filter_init(pdata, &ts->filter_data);
 942                         if (err < 0)
 943                                 goto err_free_mem;
 944                 }
 945                 ts->filter = pdata->filter;
 946                 ts->filter_cleanup = pdata->filter_cleanup;
 947         } else if (pdata->debounce_max) {
 948                 ts->debounce_max = pdata->debounce_max;
 949                 if (ts->debounce_max < 2)
 950                         ts->debounce_max = 2;
 951                 ts->debounce_tol = pdata->debounce_tol;
 952                 ts->debounce_rep = pdata->debounce_rep;
 953                 ts->filter = ads7846_debounce;
 954                 ts->filter_data = ts;
 955         } else
 956                 ts->filter = ads7846_no_filter;
 957
 958         err = setup_pendown(spi, ts);
 959         if (err)
 960                 goto err_cleanup_filter;
 961
 962         if (pdata->penirq_recheck_delay_usecs)
 963                 ts->penirq_recheck_delay_usecs =
 964                                 pdata->penirq_recheck_delay_usecs;
 965
 966         ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
 967
 968         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
 969         snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
 970
 971         input_dev->name = ts->name;
 972         input_dev->phys = ts->phys;
 973         input_dev->dev.parent = &spi->dev;
 974
 975         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 976         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 977         input_set_abs_params(input_dev, ABS_X,
 978                         pdata->x_min ? : 0,
 979                         pdata->x_max ? : MAX_12BIT,
 980                         0, 0);
 981         input_set_abs_params(input_dev, ABS_Y,
 982                         pdata->y_min ? : 0,
 983                         pdata->y_max ? : MAX_12BIT,
 984                         0, 0);
 985         input_set_abs_params(input_dev, ABS_PRESSURE,
 986                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 987
 988         vref = pdata->keep_vref_on;
 989
 990         /* set up the transfers to read touchscreen state; this assumes we
 991          * use formula #2 for pressure, not #3.
 992          */
 993         m = &ts->msg[0];
 994         x = ts->xfer;
 995
 996         spi_message_init(m);
 997
 998         /* y- still on; turn on only y+ (and ADC) */
 999         packet->read_y = READ_Y(vref);
1000         x->tx_buf = &packet->read_y;
1001         x->len = 1;
1002         spi_message_add_tail(x, m);
1003
1004         x++;
1005         x->rx_buf = &packet->tc.y;
1006         x->len = 2;
1007         spi_message_add_tail(x, m);
1008
1009         /* the first sample after switching drivers can be low quality;
1010          * optionally discard it, using a second one after the signals
1011          * have had enough time to stabilize.
1012          */
1013         if (pdata->settle_delay_usecs) {
1014                 x->delay_usecs = pdata->settle_delay_usecs;
1015
1016                 x++;
1017                 x->tx_buf = &packet->read_y;
1018                 x->len = 1;
1019                 spi_message_add_tail(x, m);
1020
1021                 x++;
1022                 x->rx_buf = &packet->tc.y;
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         /* turn y- off, x+ on, then leave in lowpower */
1034         x++;
1035         packet->read_x = READ_X(vref);
1036         x->tx_buf = &packet->read_x;
1037         x->len = 1;
1038         spi_message_add_tail(x, m);
1039
1040         x++;
1041         x->rx_buf = &packet->tc.x;
1042         x->len = 2;
1043         spi_message_add_tail(x, m);
1044
1045         /* ... maybe discard first sample ... */
1046         if (pdata->settle_delay_usecs) {
1047                 x->delay_usecs = pdata->settle_delay_usecs;
1048
1049                 x++;
1050                 x->tx_buf = &packet->read_x;
1051                 x->len = 1;
1052                 spi_message_add_tail(x, m);
1053
1054                 x++;
1055                 x->rx_buf = &packet->tc.x;
1056                 x->len = 2;
1057                 spi_message_add_tail(x, m);
1058         }
1059
1060         m->complete = ads7846_rx_val;
1061         m->context = ts;
1062
1063         /* turn y+ off, x- on; we'll use formula #2 */
1064         if (ts->model == 7846) {
1065                 m++;
1066                 spi_message_init(m);
1067
1068                 x++;
1069                 packet->read_z1 = READ_Z1(vref);
1070                 x->tx_buf = &packet->read_z1;
1071                 x->len = 1;
1072                 spi_message_add_tail(x, m);
1073
1074                 x++;
1075                 x->rx_buf = &packet->tc.z1;
1076                 x->len = 2;
1077                 spi_message_add_tail(x, m);
1078
1079                 /* ... maybe discard first sample ... */
1080                 if (pdata->settle_delay_usecs) {
1081                         x->delay_usecs = pdata->settle_delay_usecs;
1082
1083                         x++;
1084                         x->tx_buf = &packet->read_z1;
1085                         x->len = 1;
1086                         spi_message_add_tail(x, m);
1087
1088                         x++;
1089                         x->rx_buf = &packet->tc.z1;
1090                         x->len = 2;
1091                         spi_message_add_tail(x, m);
1092                 }
1093
1094                 m->complete = ads7846_rx_val;
1095                 m->context = ts;
1096
1097                 m++;
1098                 spi_message_init(m);
1099
1100                 x++;
1101                 packet->read_z2 = READ_Z2(vref);
1102                 x->tx_buf = &packet->read_z2;
1103                 x->len = 1;
1104                 spi_message_add_tail(x, m);
1105
1106                 x++;
1107                 x->rx_buf = &packet->tc.z2;
1108                 x->len = 2;
1109                 spi_message_add_tail(x, m);
1110
1111                 /* ... maybe discard first sample ... */
1112                 if (pdata->settle_delay_usecs) {
1113                         x->delay_usecs = pdata->settle_delay_usecs;
1114
1115                         x++;
1116                         x->tx_buf = &packet->read_z2;
1117                         x->len = 1;
1118                         spi_message_add_tail(x, m);
1119
1120                         x++;
1121                         x->rx_buf = &packet->tc.z2;
1122                         x->len = 2;
1123                         spi_message_add_tail(x, m);
1124                 }
1125
1126                 m->complete = ads7846_rx_val;
1127                 m->context = ts;
1128         }
1129
1130         /* power down */
1131         m++;
1132         spi_message_init(m);
1133
1134         x++;
1135         packet->pwrdown = PWRDOWN;
1136         x->tx_buf = &packet->pwrdown;
1137         x->len = 1;
1138         spi_message_add_tail(x, m);
1139
1140         x++;
1141         x->rx_buf = &packet->dummy;
1142         x->len = 2;
1143         CS_CHANGE(*x);
1144         spi_message_add_tail(x, m);
1145
1146         m->complete = ads7846_rx;
1147         m->context = ts;
1148
1149         ts->last_msg = m;
1150
1151         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1152                         spi->dev.driver->name, ts)) {
1153                 dev_info(&spi->dev,
1154                         "trying pin change workaround on irq %d\n", spi->irq);
1155                 err = request_irq(spi->irq, ads7846_irq,
1156                                   IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
1157                                   spi->dev.driver->name, ts);
1158                 if (err) {
1159                         dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1160                         goto err_free_gpio;
1161                 }
1162         }
1163
1164         err = ads784x_hwmon_register(spi, ts);
1165         if (err)
1166                 goto err_free_irq;
1167
1168         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1169
1170         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1171          * the touchscreen, in case it's not connected.
1172          */
1173         (void) ads7846_read12_ser(&spi->dev,
1174                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1175
1176         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1177         if (err)
1178                 goto err_remove_hwmon;
1179
1180         err = input_register_device(input_dev);
1181         if (err)
1182                 goto err_remove_attr_group;
1183
1184         return 0;
1185
1186  err_remove_attr_group:
1187         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1188  err_remove_hwmon:
1189         ads784x_hwmon_unregister(spi, ts);
1190  err_free_irq:
1191         free_irq(spi->irq, ts);
1192  err_free_gpio:
1193         if (ts->gpio_pendown != -1)
1194                 gpio_free(ts->gpio_pendown);
1195  err_cleanup_filter:
1196         if (ts->filter_cleanup)
1197                 ts->filter_cleanup(ts->filter_data);
1198  err_free_mem:
1199         input_free_device(input_dev);
1200         kfree(packet);
1201         kfree(ts);
1202         return err;
1203 }
1204
1205 static int __devexit ads7846_remove(struct spi_device *spi)
1206 {
1207         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1208
1209         ads784x_hwmon_unregister(spi, ts);
1210         input_unregister_device(ts->input);
1211
1212         ads7846_suspend(spi, PMSG_SUSPEND);
1213
1214         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1215
1216         free_irq(ts->spi->irq, ts);
1217         /* suspend left the IRQ disabled */
1218         enable_irq(ts->spi->irq);
1219
1220         if (ts->gpio_pendown != -1)
1221                 gpio_free(ts->gpio_pendown);
1222
1223         if (ts->filter_cleanup)
1224                 ts->filter_cleanup(ts->filter_data);
1225
1226         kfree(ts->packet);
1227         kfree(ts);
1228
1229         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1230         return 0;
1231 }
1232
1233 static struct spi_driver ads7846_driver = {
1234         .driver = {
1235                 .name   = "ads7846",
1236                 .bus    = &spi_bus_type,
1237                 .owner  = THIS_MODULE,
1238         },
1239         .probe          = ads7846_probe,
1240         .remove         = __devexit_p(ads7846_remove),
1241         .suspend        = ads7846_suspend,
1242         .resume         = ads7846_resume,
1243 };
1244
1245 static int __init ads7846_init(void)
1246 {
1247         return spi_register_driver(&ads7846_driver);
1248 }
1249 module_init(ads7846_init);
1250
1251 static void __exit ads7846_exit(void)
1252 {
1253         spi_unregister_driver(&ads7846_driver);
1254 }
1255 module_exit(ads7846_exit);
1256
1257 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1258 MODULE_LICENSE("GPL");
1259 MODULE_ALIAS("spi:ads7846");