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 <linux/regulator/consumer.h>
  31 #include <asm/irq.h>
  32
  33 /*
  34  * This code has been heavily tested on a Nokia 770, and lightly
  35  * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
  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  * Support for Analog Devices AD7873 and AD7843 tested.
  40  *
  41  * IRQ handling needs a workaround because of a shortcoming in handling
  42  * edge triggered IRQs on some platforms like the OMAP1/2. These
  43  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  44  * have to maintain our own SW IRQ disabled status. This should be
  45  * removed as soon as the affected platform's IRQ handling is fixed.
  46  *
  47  * App note sbaa036 talks in more detail about accurate sampling...
  48  * that ought to help in situations like LCDs inducing noise (which
  49  * can also be helped by using synch signals) and more generally.
  50  * This driver tries to utilize the measures described in the app
  51  * note. The strength of filtering can be set in the board-* specific
  52  * files.
  53  */
  54
  55 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  56 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  57
  58 /* this driver doesn't aim at the peak continuous sample rate */
  59 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  60
  61 struct ts_event {
  62         /* For portability, we can't read 12 bit values using SPI (which
  63          * would make the controller deliver them as native byteorder u16
  64          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  65          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  66          */
  67         u16     x;
  68         u16     y;
  69         u16     z1, z2;
  70         int     ignore;
  71 };
  72
  73 /*
  74  * We allocate this separately to avoid cache line sharing issues when
  75  * driver is used with DMA-based SPI controllers (like atmel_spi) on
  76  * systems where main memory is not DMA-coherent (most non-x86 boards).
  77  */
  78 struct ads7846_packet {
  79         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  80         u16                     dummy;          /* for the pwrdown read */
  81         struct ts_event         tc;
  82 };
  83
  84 struct ads7846 {
  85         struct input_dev        *input;
  86         char                    phys[32];
  87         char                    name[32];
  88
  89         struct spi_device       *spi;
  90         struct regulator        *reg;
  91
  92 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  93         struct attribute_group  *attr_group;
  94         struct device           *hwmon;
  95 #endif
  96
  97         u16                     model;
  98         u16                     vref_mv;
  99         u16                     vref_delay_usecs;
 100         u16                     x_plate_ohms;
 101         u16                     pressure_max;
 102
 103         bool                    swap_xy;
 104
 105         struct ads7846_packet   *packet;
 106
 107         struct spi_transfer     xfer[18];
 108         struct spi_message      msg[5];
 109         struct spi_message      *last_msg;
 110         int                     msg_idx;
 111         int                     read_cnt;
 112         int                     read_rep;
 113         int                     last_read;
 114
 115         u16                     debounce_max;
 116         u16                     debounce_tol;
 117         u16                     debounce_rep;
 118
 119         u16                     penirq_recheck_delay_usecs;
 120
 121         spinlock_t              lock;
 122         struct hrtimer          timer;
 123         unsigned                pendown:1;      /* P: lock */
 124         unsigned                pending:1;      /* P: lock */
 125 // FIXME remove "irq_disabled"
 126         unsigned                irq_disabled:1; /* P: lock */
 127         unsigned                disabled:1;
 128         unsigned                is_suspended:1;
 129
 130         int                     (*filter)(void *data, int data_idx, int *val);
 131         void                    *filter_data;
 132         void                    (*filter_cleanup)(void *data);
 133         int                     (*get_pendown_state)(void);
 134         int                     gpio_pendown;
 135
 136         void                    (*wait_for_sync)(void);
 137 };
 138
 139 /* leave chip selected when we're done, for quicker re-select? */
 140 #if     0
 141 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 142 #else
 143 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 144 #endif
 145
 146 /*--------------------------------------------------------------------------*/
 147
 148 /* The ADS7846 has touchscreen and other sensors.
 149  * Earlier ads784x chips are somewhat compatible.
 150  */
 151 #define ADS_START               (1 << 7)
 152 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 153 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 154 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 155 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 156 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 157 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 158 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 159 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 160 #define ADS_8_BIT               (1 << 3)
 161 #define ADS_12_BIT              (0 << 3)
 162 #define ADS_SER                 (1 << 2)        /* non-differential */
 163 #define ADS_DFR                 (0 << 2)        /* differential */
 164 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 165 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 166 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 167 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 168
 169 #define MAX_12BIT       ((1<<12)-1)
 170
 171 /* leave ADC powered up (disables penirq) between differential samples */
 172 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 173         | ADS_12_BIT | ADS_DFR | \
 174         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 175
 176 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 177 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 178 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 179
 180 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 181 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 182
 183 /* single-ended samples need to first power up reference voltage;
 184  * we leave both ADC and VREF powered
 185  */
 186 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 187         | ADS_12_BIT | ADS_SER)
 188
 189 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 190 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 191
 192 /*--------------------------------------------------------------------------*/
 193
 194 /*
 195  * Non-touchscreen sensors only use single-ended conversions.
 196  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 197  * ads7846 lets that pin be unconnected, to use internal vREF.
 198  */
 199
 200 struct ser_req {
 201         u8                      ref_on;
 202         u8                      command;
 203         u8                      ref_off;
 204         u16                     scratch;
 205         __be16                  sample;
 206         struct spi_message      msg;
 207         struct spi_transfer     xfer[6];
 208 };
 209
 210 static void ads7846_enable(struct ads7846 *ts);
 211 static void ads7846_disable(struct ads7846 *ts);
 212
 213 static int device_suspended(struct device *dev)
 214 {
 215         struct ads7846 *ts = dev_get_drvdata(dev);
 216         return ts->is_suspended || ts->disabled;
 217 }
 218
 219 static int ads7846_read12_ser(struct device *dev, unsigned command)
 220 {
 221         struct spi_device       *spi = to_spi_device(dev);
 222         struct ads7846          *ts = dev_get_drvdata(dev);
 223         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 224         int                     status;
 225         int                     use_internal;
 226
 227         if (!req)
 228                 return -ENOMEM;
 229
 230         spi_message_init(&req->msg);
 231
 232         /* FIXME boards with ads7846 might use external vref instead ... */
 233         use_internal = (ts->model == 7846);
 234
 235         /* maybe turn on internal vREF, and let it settle */
 236         if (use_internal) {
 237                 req->ref_on = REF_ON;
 238                 req->xfer[0].tx_buf = &req->ref_on;
 239                 req->xfer[0].len = 1;
 240                 spi_message_add_tail(&req->xfer[0], &req->msg);
 241
 242                 req->xfer[1].rx_buf = &req->scratch;
 243                 req->xfer[1].len = 2;
 244
 245                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 246                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 247                 spi_message_add_tail(&req->xfer[1], &req->msg);
 248         }
 249
 250         /* take sample */
 251         req->command = (u8) command;
 252         req->xfer[2].tx_buf = &req->command;
 253         req->xfer[2].len = 1;
 254         spi_message_add_tail(&req->xfer[2], &req->msg);
 255
 256         req->xfer[3].rx_buf = &req->sample;
 257         req->xfer[3].len = 2;
 258         spi_message_add_tail(&req->xfer[3], &req->msg);
 259
 260         /* REVISIT:  take a few more samples, and compare ... */
 261
 262         /* converter in low power mode & enable PENIRQ */
 263         req->ref_off = PWRDOWN;
 264         req->xfer[4].tx_buf = &req->ref_off;
 265         req->xfer[4].len = 1;
 266         spi_message_add_tail(&req->xfer[4], &req->msg);
 267
 268         req->xfer[5].rx_buf = &req->scratch;
 269         req->xfer[5].len = 2;
 270         CS_CHANGE(req->xfer[5]);
 271         spi_message_add_tail(&req->xfer[5], &req->msg);
 272
 273         ts->irq_disabled = 1;
 274         disable_irq(spi->irq);
 275         status = spi_sync(spi, &req->msg);
 276         ts->irq_disabled = 0;
 277         enable_irq(spi->irq);
 278
 279         if (status == 0) {
 280                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 281                 status = be16_to_cpu(req->sample);
 282                 status = status >> 3;
 283                 status &= 0x0fff;
 284         }
 285
 286         kfree(req);
 287         return status;
 288 }
 289
 290 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 291
 292 #define SHOW(name, var, adjust) static ssize_t \
 293 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 294 { \
 295         struct ads7846 *ts = dev_get_drvdata(dev); \
 296         ssize_t v = ads7846_read12_ser(dev, \
 297                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 298         if (v < 0) \
 299                 return v; \
 300         return sprintf(buf, "%u\n", adjust(ts, v)); \
 301 } \
 302 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 303
 304
 305 /* Sysfs conventions report temperatures in millidegrees Celsius.
 306  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 307  * accuracy scheme without calibration data.  For now we won't try either;
 308  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 309  */
 310 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 311 {
 312         return v;
 313 }
 314
 315 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 316 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 317
 318
 319 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 320  * if we know vREF.  userspace may need to scale vAUX to match the board's
 321  * external resistors; we assume that vBATT only uses the internal ones.
 322  */
 323 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 324 {
 325         unsigned retval = v;
 326
 327         /* external resistors may scale vAUX into 0..vREF */
 328         retval *= ts->vref_mv;
 329         retval = retval >> 12;
 330         return retval;
 331 }
 332
 333 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 334 {
 335         unsigned retval = vaux_adjust(ts, v);
 336
 337         /* ads7846 has a resistor ladder to scale this signal down */
 338         if (ts->model == 7846)
 339                 retval *= 4;
 340         return retval;
 341 }
 342
 343 SHOW(in0_input, vaux, vaux_adjust)
 344 SHOW(in1_input, vbatt, vbatt_adjust)
 345
 346
 347 static struct attribute *ads7846_attributes[] = {
 348         &dev_attr_temp0.attr,
 349         &dev_attr_temp1.attr,
 350         &dev_attr_in0_input.attr,
 351         &dev_attr_in1_input.attr,
 352         NULL,
 353 };
 354
 355 static struct attribute_group ads7846_attr_group = {
 356         .attrs = ads7846_attributes,
 357 };
 358
 359 static struct attribute *ads7843_attributes[] = {
 360         &dev_attr_in0_input.attr,
 361         &dev_attr_in1_input.attr,
 362         NULL,
 363 };
 364
 365 static struct attribute_group ads7843_attr_group = {
 366         .attrs = ads7843_attributes,
 367 };
 368
 369 static struct attribute *ads7845_attributes[] = {
 370         &dev_attr_in0_input.attr,
 371         NULL,
 372 };
 373
 374 static struct attribute_group ads7845_attr_group = {
 375         .attrs = ads7845_attributes,
 376 };
 377
 378 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 379 {
 380         struct device *hwmon;
 381         int err;
 382
 383         /* hwmon sensors need a reference voltage */
 384         switch (ts->model) {
 385         case 7846:
 386                 if (!ts->vref_mv) {
 387                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 388                         ts->vref_mv = 2500;
 389                 }
 390                 break;
 391         case 7845:
 392         case 7843:
 393                 if (!ts->vref_mv) {
 394                         dev_warn(&spi->dev,
 395                                 "external vREF for ADS%d not specified\n",
 396                                 ts->model);
 397                         return 0;
 398                 }
 399                 break;
 400         }
 401
 402         /* different chips have different sensor groups */
 403         switch (ts->model) {
 404         case 7846:
 405                 ts->attr_group = &ads7846_attr_group;
 406                 break;
 407         case 7845:
 408                 ts->attr_group = &ads7845_attr_group;
 409                 break;
 410         case 7843:
 411                 ts->attr_group = &ads7843_attr_group;
 412                 break;
 413         default:
 414                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 415                 return 0;
 416         }
 417
 418         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 419         if (err)
 420                 return err;
 421
 422         hwmon = hwmon_device_register(&spi->dev);
 423         if (IS_ERR(hwmon)) {
 424                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 425                 return PTR_ERR(hwmon);
 426         }
 427
 428         ts->hwmon = hwmon;
 429         return 0;
 430 }
 431
 432 static void ads784x_hwmon_unregister(struct spi_device *spi,
 433                                      struct ads7846 *ts)
 434 {
 435         if (ts->hwmon) {
 436                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 437                 hwmon_device_unregister(ts->hwmon);
 438         }
 439 }
 440
 441 #else
 442 static inline int ads784x_hwmon_register(struct spi_device *spi,
 443                                          struct ads7846 *ts)
 444 {
 445         return 0;
 446 }
 447
 448 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 449                                             struct ads7846 *ts)
 450 {
 451 }
 452 #endif
 453
 454 static int is_pen_down(struct device *dev)
 455 {
 456         struct ads7846  *ts = dev_get_drvdata(dev);
 457
 458         return ts->pendown;
 459 }
 460
 461 static ssize_t ads7846_pen_down_show(struct device *dev,
 462                                      struct device_attribute *attr, char *buf)
 463 {
 464         return sprintf(buf, "%u\n", is_pen_down(dev));
 465 }
 466
 467 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 468
 469 static ssize_t ads7846_disable_show(struct device *dev,
 470                                      struct device_attribute *attr, char *buf)
 471 {
 472         struct ads7846  *ts = dev_get_drvdata(dev);
 473
 474         return sprintf(buf, "%u\n", ts->disabled);
 475 }
 476
 477 static ssize_t ads7846_disable_store(struct device *dev,
 478                                      struct device_attribute *attr,
 479                                      const char *buf, size_t count)
 480 {
 481         struct ads7846 *ts = dev_get_drvdata(dev);
 482         unsigned long i;
 483
 484         if (strict_strtoul(buf, 10, &i))
 485                 return -EINVAL;
 486
 487         spin_lock_irq(&ts->lock);
 488
 489         if (i)
 490                 ads7846_disable(ts);
 491         else
 492                 ads7846_enable(ts);
 493
 494         spin_unlock_irq(&ts->lock);
 495
 496         return count;
 497 }
 498
 499 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 500
 501 static struct attribute *ads784x_attributes[] = {
 502         &dev_attr_pen_down.attr,
 503         &dev_attr_disable.attr,
 504         NULL,
 505 };
 506
 507 static struct attribute_group ads784x_attr_group = {
 508         .attrs = ads784x_attributes,
 509 };
 510
 511 /*--------------------------------------------------------------------------*/
 512
 513 static int get_pendown_state(struct ads7846 *ts)
 514 {
 515         if (ts->get_pendown_state)
 516                 return ts->get_pendown_state();
 517
 518         return !gpio_get_value(ts->gpio_pendown);
 519 }
 520
 521 static void null_wait_for_sync(void)
 522 {
 523 }
 524
 525 /*
 526  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 527  * to retrieve touchscreen status.
 528  *
 529  * The SPI transfer completion callback does the real work.  It reports
 530  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 531  */
 532
 533 static void ads7846_rx(void *ads)
 534 {
 535         struct ads7846          *ts = ads;
 536         struct ads7846_packet   *packet = ts->packet;
 537         unsigned                Rt;
 538         u16                     x, y, z1, z2;
 539
 540         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 541          * on-the-wire format as part of debouncing to get stable readings.
 542          */
 543         x = packet->tc.x;
 544         y = packet->tc.y;
 545         z1 = packet->tc.z1;
 546         z2 = packet->tc.z2;
 547
 548         /* range filtering */
 549         if (x == MAX_12BIT)
 550                 x = 0;
 551
 552         if (ts->model == 7843) {
 553                 Rt = ts->pressure_max / 2;
 554         } else if (likely(x && z1)) {
 555                 /* compute touch pressure resistance using equation #2 */
 556                 Rt = z2;
 557                 Rt -= z1;
 558                 Rt *= x;
 559                 Rt *= ts->x_plate_ohms;
 560                 Rt /= z1;
 561                 Rt = (Rt + 2047) >> 12;
 562         } else {
 563                 Rt = 0;
 564         }
 565
 566         /* Sample found inconsistent by debouncing or pressure is beyond
 567          * the maximum. Don't report it to user space, repeat at least
 568          * once more the measurement
 569          */
 570         if (packet->tc.ignore || Rt > ts->pressure_max) {
 571                 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
 572                          packet->tc.ignore, Rt);
 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                         dev_vdbg(&ts->spi->dev, "DOWN\n");
 602                 }
 603
 604                 if (ts->swap_xy)
 605                         swap(x, y);
 606
 607                 input_report_abs(input, ABS_X, x);
 608                 input_report_abs(input, ABS_Y, y);
 609                 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
 610
 611                 input_sync(input);
 612                 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 613         }
 614
 615         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 616                         HRTIMER_MODE_REL);
 617 }
 618
 619 static int ads7846_debounce(void *ads, int data_idx, int *val)
 620 {
 621         struct ads7846          *ts = ads;
 622
 623         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 624                 /* Start over collecting consistent readings. */
 625                 ts->read_rep = 0;
 626                 /* Repeat it, if this was the first read or the read
 627                  * wasn't consistent enough. */
 628                 if (ts->read_cnt < ts->debounce_max) {
 629                         ts->last_read = *val;
 630                         ts->read_cnt++;
 631                         return ADS7846_FILTER_REPEAT;
 632                 } else {
 633                         /* Maximum number of debouncing reached and still
 634                          * not enough number of consistent readings. Abort
 635                          * the whole sample, repeat it in the next sampling
 636                          * period.
 637                          */
 638                         ts->read_cnt = 0;
 639                         return ADS7846_FILTER_IGNORE;
 640                 }
 641         } else {
 642                 if (++ts->read_rep > ts->debounce_rep) {
 643                         /* Got a good reading for this coordinate,
 644                          * go for the next one. */
 645                         ts->read_cnt = 0;
 646                         ts->read_rep = 0;
 647                         return ADS7846_FILTER_OK;
 648                 } else {
 649                         /* Read more values that are consistent. */
 650                         ts->read_cnt++;
 651                         return ADS7846_FILTER_REPEAT;
 652                 }
 653         }
 654 }
 655
 656 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 657 {
 658         return ADS7846_FILTER_OK;
 659 }
 660
 661 static void ads7846_rx_val(void *ads)
 662 {
 663         struct ads7846 *ts = ads;
 664         struct ads7846_packet *packet = ts->packet;
 665         struct spi_message *m;
 666         struct spi_transfer *t;
 667         int val;
 668         int action;
 669         int status;
 670
 671         m = &ts->msg[ts->msg_idx];
 672         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 673
 674         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 675          * built from two 8 bit values written msb-first.
 676          */
 677         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 678
 679         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 680         switch (action) {
 681         case ADS7846_FILTER_REPEAT:
 682                 break;
 683         case ADS7846_FILTER_IGNORE:
 684                 packet->tc.ignore = 1;
 685                 /* Last message will contain ads7846_rx() as the
 686                  * completion function.
 687                  */
 688                 m = ts->last_msg;
 689                 break;
 690         case ADS7846_FILTER_OK:
 691                 *(u16 *)t->rx_buf = val;
 692                 packet->tc.ignore = 0;
 693                 m = &ts->msg[++ts->msg_idx];
 694                 break;
 695         default:
 696                 BUG();
 697         }
 698         ts->wait_for_sync();
 699         status = spi_async(ts->spi, m);
 700         if (status)
 701                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 702                                 status);
 703 }
 704
 705 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 706 {
 707         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 708         int             status = 0;
 709
 710         spin_lock(&ts->lock);
 711
 712         if (unlikely(!get_pendown_state(ts) ||
 713                      device_suspended(&ts->spi->dev))) {
 714                 if (ts->pendown) {
 715                         struct input_dev *input = ts->input;
 716
 717                         input_report_key(input, BTN_TOUCH, 0);
 718                         input_report_abs(input, ABS_PRESSURE, 0);
 719                         input_sync(input);
 720
 721                         ts->pendown = 0;
 722                         dev_vdbg(&ts->spi->dev, "UP\n");
 723                 }
 724
 725                 /* measurement cycle ended */
 726                 if (!device_suspended(&ts->spi->dev)) {
 727                         ts->irq_disabled = 0;
 728                         enable_irq(ts->spi->irq);
 729                 }
 730                 ts->pending = 0;
 731         } else {
 732                 /* pen is still down, continue with the measurement */
 733                 ts->msg_idx = 0;
 734                 ts->wait_for_sync();
 735                 status = spi_async(ts->spi, &ts->msg[0]);
 736                 if (status)
 737                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 738         }
 739
 740         spin_unlock(&ts->lock);
 741         return HRTIMER_NORESTART;
 742 }
 743
 744 static irqreturn_t ads7846_irq(int irq, void *handle)
 745 {
 746         struct ads7846 *ts = handle;
 747         unsigned long flags;
 748
 749         spin_lock_irqsave(&ts->lock, flags);
 750         if (likely(get_pendown_state(ts))) {
 751                 if (!ts->irq_disabled) {
 752                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 753                          * like the other dispatchers:  it will report IRQs
 754                          * even after they've been disabled.  We work around
 755                          * that here.  (The "generic irq" framework may help...)
 756                          */
 757                         ts->irq_disabled = 1;
 758                         disable_irq_nosync(ts->spi->irq);
 759                         ts->pending = 1;
 760                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 761                                         HRTIMER_MODE_REL);
 762                 }
 763         }
 764         spin_unlock_irqrestore(&ts->lock, flags);
 765
 766         return IRQ_HANDLED;
 767 }
 768
 769 /*--------------------------------------------------------------------------*/
 770
 771 /* Must be called with ts->lock held */
 772 static void ads7846_disable(struct ads7846 *ts)
 773 {
 774         if (ts->disabled)
 775                 return;
 776
 777         ts->disabled = 1;
 778
 779         /* are we waiting for IRQ, or polling? */
 780         if (!ts->pending) {
 781                 ts->irq_disabled = 1;
 782                 disable_irq(ts->spi->irq);
 783         } else {
 784                 /* the timer will run at least once more, and
 785                  * leave everything in a clean state, IRQ disabled
 786                  */
 787                 while (ts->pending) {
 788                         spin_unlock_irq(&ts->lock);
 789                         msleep(1);
 790                         spin_lock_irq(&ts->lock);
 791                 }
 792         }
 793
 794         regulator_disable(ts->reg);
 795
 796         /* we know the chip's in lowpower mode since we always
 797          * leave it that way after every request
 798          */
 799 }
 800
 801 /* Must be called with ts->lock held */
 802 static void ads7846_enable(struct ads7846 *ts)
 803 {
 804         if (!ts->disabled)
 805                 return;
 806
 807         regulator_enable(ts->reg);
 808
 809         ts->disabled = 0;
 810         ts->irq_disabled = 0;
 811         enable_irq(ts->spi->irq);
 812 }
 813
 814 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 815 {
 816         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 817
 818         spin_lock_irq(&ts->lock);
 819
 820         ts->is_suspended = 1;
 821         ads7846_disable(ts);
 822
 823         spin_unlock_irq(&ts->lock);
 824
 825         if (device_may_wakeup(&ts->spi->dev))
 826                 enable_irq_wake(ts->spi->irq);
 827
 828         return 0;
 829
 830 }
 831
 832 static int ads7846_resume(struct spi_device *spi)
 833 {
 834         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 835
 836         if (device_may_wakeup(&ts->spi->dev))
 837                 disable_irq_wake(ts->spi->irq);
 838
 839         spin_lock_irq(&ts->lock);
 840
 841         ts->is_suspended = 0;
 842         ads7846_enable(ts);
 843
 844         spin_unlock_irq(&ts->lock);
 845
 846         return 0;
 847 }
 848
 849 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 850 {
 851         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 852         int err;
 853
 854         /* REVISIT when the irq can be triggered active-low, or if for some
 855          * reason the touchscreen isn't hooked up, we don't need to access
 856          * the pendown state.
 857          */
 858         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
 859                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 860                 return -EINVAL;
 861         }
 862
 863         if (pdata->get_pendown_state) {
 864                 ts->get_pendown_state = pdata->get_pendown_state;
 865                 return 0;
 866         }
 867
 868         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 869         if (err) {
 870                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 871                                 pdata->gpio_pendown);
 872                 return err;
 873         }
 874
 875         ts->gpio_pendown = pdata->gpio_pendown;
 876         return 0;
 877 }
 878
 879 static int __devinit ads7846_probe(struct spi_device *spi)
 880 {
 881         struct ads7846                  *ts;
 882         struct ads7846_packet           *packet;
 883         struct input_dev                *input_dev;
 884         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 885         struct spi_message              *m;
 886         struct spi_transfer             *x;
 887         int                             vref;
 888         int                             err;
 889
 890         if (!spi->irq) {
 891                 dev_dbg(&spi->dev, "no IRQ?\n");
 892                 return -ENODEV;
 893         }
 894
 895         if (!pdata) {
 896                 dev_dbg(&spi->dev, "no platform data?\n");
 897                 return -ENODEV;
 898         }
 899
 900         /* don't exceed max specified sample rate */
 901         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 902                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 903                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 904                 return -EINVAL;
 905         }
 906
 907         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 908          * that even if the hardware can do that, the SPI controller driver
 909          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 910          */
 911         spi->bits_per_word = 8;
 912         spi->mode = SPI_MODE_0;
 913         err = spi_setup(spi);
 914         if (err < 0)
 915                 return err;
 916
 917         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 918         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
 919         input_dev = input_allocate_device();
 920         if (!ts || !packet || !input_dev) {
 921                 err = -ENOMEM;
 922                 goto err_free_mem;
 923         }
 924
 925         dev_set_drvdata(&spi->dev, ts);
 926
 927         ts->packet = packet;
 928         ts->spi = spi;
 929         ts->input = input_dev;
 930         ts->vref_mv = pdata->vref_mv;
 931         ts->swap_xy = pdata->swap_xy;
 932
 933         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 934         ts->timer.function = ads7846_timer;
 935
 936         spin_lock_init(&ts->lock);
 937
 938         ts->model = pdata->model ? : 7846;
 939         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 940         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 941         ts->pressure_max = pdata->pressure_max ? : ~0;
 942
 943         if (pdata->filter != NULL) {
 944                 if (pdata->filter_init != NULL) {
 945                         err = pdata->filter_init(pdata, &ts->filter_data);
 946                         if (err < 0)
 947                                 goto err_free_mem;
 948                 }
 949                 ts->filter = pdata->filter;
 950                 ts->filter_cleanup = pdata->filter_cleanup;
 951         } else if (pdata->debounce_max) {
 952                 ts->debounce_max = pdata->debounce_max;
 953                 if (ts->debounce_max < 2)
 954                         ts->debounce_max = 2;
 955                 ts->debounce_tol = pdata->debounce_tol;
 956                 ts->debounce_rep = pdata->debounce_rep;
 957                 ts->filter = ads7846_debounce;
 958                 ts->filter_data = ts;
 959         } else
 960                 ts->filter = ads7846_no_filter;
 961
 962         err = setup_pendown(spi, ts);
 963         if (err)
 964                 goto err_cleanup_filter;
 965
 966         if (pdata->penirq_recheck_delay_usecs)
 967                 ts->penirq_recheck_delay_usecs =
 968                                 pdata->penirq_recheck_delay_usecs;
 969
 970         ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
 971
 972         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
 973         snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
 974
 975         input_dev->name = ts->name;
 976         input_dev->phys = ts->phys;
 977         input_dev->dev.parent = &spi->dev;
 978
 979         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 980         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 981         input_set_abs_params(input_dev, ABS_X,
 982                         pdata->x_min ? : 0,
 983                         pdata->x_max ? : MAX_12BIT,
 984                         0, 0);
 985         input_set_abs_params(input_dev, ABS_Y,
 986                         pdata->y_min ? : 0,
 987                         pdata->y_max ? : MAX_12BIT,
 988                         0, 0);
 989         input_set_abs_params(input_dev, ABS_PRESSURE,
 990                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 991
 992         vref = pdata->keep_vref_on;
 993
 994         if (ts->model == 7873) {
 995                 /* The AD7873 is almost identical to the ADS7846
 996                  * keep VREF off during differential/ratiometric
 997                  * conversion modes
 998                  */
 999                 ts->model = 7846;
1000                 vref = 0;
1001         }
1002
1003         /* set up the transfers to read touchscreen state; this assumes we
1004          * use formula #2 for pressure, not #3.
1005          */
1006         m = &ts->msg[0];
1007         x = ts->xfer;
1008
1009         spi_message_init(m);
1010
1011         /* y- still on; turn on only y+ (and ADC) */
1012         packet->read_y = READ_Y(vref);
1013         x->tx_buf = &packet->read_y;
1014         x->len = 1;
1015         spi_message_add_tail(x, m);
1016
1017         x++;
1018         x->rx_buf = &packet->tc.y;
1019         x->len = 2;
1020         spi_message_add_tail(x, m);
1021
1022         /* the first sample after switching drivers can be low quality;
1023          * optionally discard it, using a second one after the signals
1024          * have had enough time to stabilize.
1025          */
1026         if (pdata->settle_delay_usecs) {
1027                 x->delay_usecs = pdata->settle_delay_usecs;
1028
1029                 x++;
1030                 x->tx_buf = &packet->read_y;
1031                 x->len = 1;
1032                 spi_message_add_tail(x, m);
1033
1034                 x++;
1035                 x->rx_buf = &packet->tc.y;
1036                 x->len = 2;
1037                 spi_message_add_tail(x, m);
1038         }
1039
1040         m->complete = ads7846_rx_val;
1041         m->context = ts;
1042
1043         m++;
1044         spi_message_init(m);
1045
1046         /* turn y- off, x+ on, then leave in lowpower */
1047         x++;
1048         packet->read_x = READ_X(vref);
1049         x->tx_buf = &packet->read_x;
1050         x->len = 1;
1051         spi_message_add_tail(x, m);
1052
1053         x++;
1054         x->rx_buf = &packet->tc.x;
1055         x->len = 2;
1056         spi_message_add_tail(x, m);
1057
1058         /* ... maybe discard first sample ... */
1059         if (pdata->settle_delay_usecs) {
1060                 x->delay_usecs = pdata->settle_delay_usecs;
1061
1062                 x++;
1063                 x->tx_buf = &packet->read_x;
1064                 x->len = 1;
1065                 spi_message_add_tail(x, m);
1066
1067                 x++;
1068                 x->rx_buf = &packet->tc.x;
1069                 x->len = 2;
1070                 spi_message_add_tail(x, m);
1071         }
1072
1073         m->complete = ads7846_rx_val;
1074         m->context = ts;
1075
1076         /* turn y+ off, x- on; we'll use formula #2 */
1077         if (ts->model == 7846) {
1078                 m++;
1079                 spi_message_init(m);
1080
1081                 x++;
1082                 packet->read_z1 = READ_Z1(vref);
1083                 x->tx_buf = &packet->read_z1;
1084                 x->len = 1;
1085                 spi_message_add_tail(x, m);
1086
1087                 x++;
1088                 x->rx_buf = &packet->tc.z1;
1089                 x->len = 2;
1090                 spi_message_add_tail(x, m);
1091
1092                 /* ... maybe discard first sample ... */
1093                 if (pdata->settle_delay_usecs) {
1094                         x->delay_usecs = pdata->settle_delay_usecs;
1095
1096                         x++;
1097                         x->tx_buf = &packet->read_z1;
1098                         x->len = 1;
1099                         spi_message_add_tail(x, m);
1100
1101                         x++;
1102                         x->rx_buf = &packet->tc.z1;
1103                         x->len = 2;
1104                         spi_message_add_tail(x, m);
1105                 }
1106
1107                 m->complete = ads7846_rx_val;
1108                 m->context = ts;
1109
1110                 m++;
1111                 spi_message_init(m);
1112
1113                 x++;
1114                 packet->read_z2 = READ_Z2(vref);
1115                 x->tx_buf = &packet->read_z2;
1116                 x->len = 1;
1117                 spi_message_add_tail(x, m);
1118
1119                 x++;
1120                 x->rx_buf = &packet->tc.z2;
1121                 x->len = 2;
1122                 spi_message_add_tail(x, m);
1123
1124                 /* ... maybe discard first sample ... */
1125                 if (pdata->settle_delay_usecs) {
1126                         x->delay_usecs = pdata->settle_delay_usecs;
1127
1128                         x++;
1129                         x->tx_buf = &packet->read_z2;
1130                         x->len = 1;
1131                         spi_message_add_tail(x, m);
1132
1133                         x++;
1134                         x->rx_buf = &packet->tc.z2;
1135                         x->len = 2;
1136                         spi_message_add_tail(x, m);
1137                 }
1138
1139                 m->complete = ads7846_rx_val;
1140                 m->context = ts;
1141         }
1142
1143         /* power down */
1144         m++;
1145         spi_message_init(m);
1146
1147         x++;
1148         packet->pwrdown = PWRDOWN;
1149         x->tx_buf = &packet->pwrdown;
1150         x->len = 1;
1151         spi_message_add_tail(x, m);
1152
1153         x++;
1154         x->rx_buf = &packet->dummy;
1155         x->len = 2;
1156         CS_CHANGE(*x);
1157         spi_message_add_tail(x, m);
1158
1159         m->complete = ads7846_rx;
1160         m->context = ts;
1161
1162         ts->last_msg = m;
1163
1164         ts->reg = regulator_get(&spi->dev, "vcc");
1165         if (IS_ERR(ts->reg)) {
1166                 err = PTR_ERR(ts->reg);
1167                 dev_err(&spi->dev, "unable to get regulator: %ld\n", err);
1168                 goto err_free_gpio;
1169         }
1170
1171         err = regulator_enable(ts->reg);
1172         if (err) {
1173                 dev_err(&spi->dev, "unable to enable regulator: %d\n", err);
1174                 goto err_put_regulator;
1175         }
1176
1177         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1178                         spi->dev.driver->name, ts)) {
1179                 dev_info(&spi->dev,
1180                         "trying pin change workaround on irq %d\n", spi->irq);
1181                 err = request_irq(spi->irq, ads7846_irq,
1182                                   IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
1183                                   spi->dev.driver->name, ts);
1184                 if (err) {
1185                         dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1186                         goto err_disable_regulator;
1187                 }
1188         }
1189
1190         err = ads784x_hwmon_register(spi, ts);
1191         if (err)
1192                 goto err_free_irq;
1193
1194         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1195
1196         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1197          * the touchscreen, in case it's not connected.
1198          */
1199         (void) ads7846_read12_ser(&spi->dev,
1200                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1201
1202         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1203         if (err)
1204                 goto err_remove_hwmon;
1205
1206         err = input_register_device(input_dev);
1207         if (err)
1208                 goto err_remove_attr_group;
1209
1210         device_init_wakeup(&spi->dev, pdata->wakeup);
1211
1212         return 0;
1213
1214  err_remove_attr_group:
1215         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1216  err_remove_hwmon:
1217         ads784x_hwmon_unregister(spi, ts);
1218  err_free_irq:
1219         free_irq(spi->irq, ts);
1220  err_disable_regulator:
1221         regulator_disable(ts->reg);
1222  err_put_regulator:
1223         regulator_put(ts->reg);
1224  err_free_gpio:
1225         if (ts->gpio_pendown != -1)
1226                 gpio_free(ts->gpio_pendown);
1227  err_cleanup_filter:
1228         if (ts->filter_cleanup)
1229                 ts->filter_cleanup(ts->filter_data);
1230  err_free_mem:
1231         input_free_device(input_dev);
1232         kfree(packet);
1233         kfree(ts);
1234         return err;
1235 }
1236
1237 static int __devexit ads7846_remove(struct spi_device *spi)
1238 {
1239         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1240
1241         device_init_wakeup(&spi->dev, false);
1242
1243         ads784x_hwmon_unregister(spi, ts);
1244         input_unregister_device(ts->input);
1245
1246         ads7846_suspend(spi, PMSG_SUSPEND);
1247
1248         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1249
1250         free_irq(ts->spi->irq, ts);
1251         /* suspend left the IRQ disabled */
1252         enable_irq(ts->spi->irq);
1253
1254         regulator_disable(ts->reg);
1255         regulator_put(ts->reg);
1256
1257         if (ts->gpio_pendown != -1)
1258                 gpio_free(ts->gpio_pendown);
1259
1260         if (ts->filter_cleanup)
1261                 ts->filter_cleanup(ts->filter_data);
1262
1263         kfree(ts->packet);
1264         kfree(ts);
1265
1266         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1267         return 0;
1268 }
1269
1270 static struct spi_driver ads7846_driver = {
1271         .driver = {
1272                 .name   = "ads7846",
1273                 .bus    = &spi_bus_type,
1274                 .owner  = THIS_MODULE,
1275         },
1276         .probe          = ads7846_probe,
1277         .remove         = __devexit_p(ads7846_remove),
1278         .suspend        = ads7846_suspend,
1279         .resume         = ads7846_resume,
1280 };
1281
1282 static int __init ads7846_init(void)
1283 {
1284         return spi_register_driver(&ads7846_driver);
1285 }
1286 module_init(ads7846_init);
1287
1288 static void __exit ads7846_exit(void)
1289 {
1290         spi_unregister_driver(&ads7846_driver);
1291 }
1292 module_exit(ads7846_exit);
1293
1294 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1295 MODULE_LICENSE("GPL");
1296 MODULE_ALIAS("spi:ads7846");