git.oblomov.eu Git - linux-2.6/blob - drivers/input/touchscreen/ads7846.c

   1 /*
   2  * ADS7846 based touchscreen and sensor driver
   3  *
   4  * Copyright (c) 2005 David Brownell
   5  * Copyright (c) 2006 Nokia Corporation
   6  * Various changes: Imre Deak <imre.deak@nokia.com>
   7  *
   8  * Using code from:
   9  *  - corgi_ts.c
  10  *      Copyright (C) 2004-2005 Richard Purdie
  11  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  12  *      Copyright (C) 2002 MontaVista Software
  13  *      Copyright (C) 2004 Texas Instruments
  14  *      Copyright (C) 2005 Dirk Behme
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License version 2 as
  18  *  published by the Free Software Foundation.
  19  */
  20 #include <linux/hwmon.h>
  21 #include <linux/init.h>
  22 #include <linux/err.h>
  23 #include <linux/delay.h>
  24 #include <linux/input.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/slab.h>
  27 #include <linux/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
  87         struct spi_device       *spi;
  88
  89 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  90         struct attribute_group  *attr_group;
  91         struct device           *hwmon;
  92 #endif
  93
  94         u16                     model;
  95         u16                     vref_mv;
  96         u16                     vref_delay_usecs;
  97         u16                     x_plate_ohms;
  98         u16                     pressure_max;
  99
 100         struct ads7846_packet   *packet;
 101
 102         struct spi_transfer     xfer[18];
 103         struct spi_message      msg[5];
 104         struct spi_message      *last_msg;
 105         int                     msg_idx;
 106         int                     read_cnt;
 107         int                     read_rep;
 108         int                     last_read;
 109
 110         u16                     debounce_max;
 111         u16                     debounce_tol;
 112         u16                     debounce_rep;
 113
 114         u16                     penirq_recheck_delay_usecs;
 115
 116         spinlock_t              lock;
 117         struct hrtimer          timer;
 118         unsigned                pendown:1;      /* P: lock */
 119         unsigned                pending:1;      /* P: lock */
 120 // FIXME remove "irq_disabled"
 121         unsigned                irq_disabled:1; /* P: lock */
 122         unsigned                disabled:1;
 123         unsigned                is_suspended:1;
 124
 125         int                     (*filter)(void *data, int data_idx, int *val);
 126         void                    *filter_data;
 127         void                    (*filter_cleanup)(void *data);
 128         int                     (*get_pendown_state)(void);
 129         int                     gpio_pendown;
 130
 131         void                    (*wait_for_sync)(void);
 132 };
 133
 134 /* leave chip selected when we're done, for quicker re-select? */
 135 #if     0
 136 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 137 #else
 138 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 139 #endif
 140
 141 /*--------------------------------------------------------------------------*/
 142
 143 /* The ADS7846 has touchscreen and other sensors.
 144  * Earlier ads784x chips are somewhat compatible.
 145  */
 146 #define ADS_START               (1 << 7)
 147 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 148 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 149 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 150 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 151 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 152 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 153 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 154 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 155 #define ADS_8_BIT               (1 << 3)
 156 #define ADS_12_BIT              (0 << 3)
 157 #define ADS_SER                 (1 << 2)        /* non-differential */
 158 #define ADS_DFR                 (0 << 2)        /* differential */
 159 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 160 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 161 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 162 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 163
 164 #define MAX_12BIT       ((1<<12)-1)
 165
 166 /* leave ADC powered up (disables penirq) between differential samples */
 167 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 168         | ADS_12_BIT | ADS_DFR | \
 169         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 170
 171 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 172 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 173 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 174
 175 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 176 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 177
 178 /* single-ended samples need to first power up reference voltage;
 179  * we leave both ADC and VREF powered
 180  */
 181 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 182         | ADS_12_BIT | ADS_SER)
 183
 184 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 185 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 186
 187 /*--------------------------------------------------------------------------*/
 188
 189 /*
 190  * Non-touchscreen sensors only use single-ended conversions.
 191  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 192  * ads7846 lets that pin be unconnected, to use internal vREF.
 193  */
 194
 195 struct ser_req {
 196         u8                      ref_on;
 197         u8                      command;
 198         u8                      ref_off;
 199         u16                     scratch;
 200         __be16                  sample;
 201         struct spi_message      msg;
 202         struct spi_transfer     xfer[6];
 203 };
 204
 205 static void ads7846_enable(struct ads7846 *ts);
 206 static void ads7846_disable(struct ads7846 *ts);
 207
 208 static int device_suspended(struct device *dev)
 209 {
 210         struct ads7846 *ts = dev_get_drvdata(dev);
 211         return ts->is_suspended || ts->disabled;
 212 }
 213
 214 static int ads7846_read12_ser(struct device *dev, unsigned command)
 215 {
 216         struct spi_device       *spi = to_spi_device(dev);
 217         struct ads7846          *ts = dev_get_drvdata(dev);
 218         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 219         int                     status;
 220         int                     use_internal;
 221
 222         if (!req)
 223                 return -ENOMEM;
 224
 225         spi_message_init(&req->msg);
 226
 227         /* FIXME boards with ads7846 might use external vref instead ... */
 228         use_internal = (ts->model == 7846);
 229
 230         /* maybe turn on internal vREF, and let it settle */
 231         if (use_internal) {
 232                 req->ref_on = REF_ON;
 233                 req->xfer[0].tx_buf = &req->ref_on;
 234                 req->xfer[0].len = 1;
 235                 spi_message_add_tail(&req->xfer[0], &req->msg);
 236
 237                 req->xfer[1].rx_buf = &req->scratch;
 238                 req->xfer[1].len = 2;
 239
 240                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 241                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 242                 spi_message_add_tail(&req->xfer[1], &req->msg);
 243         }
 244
 245         /* take sample */
 246         req->command = (u8) command;
 247         req->xfer[2].tx_buf = &req->command;
 248         req->xfer[2].len = 1;
 249         spi_message_add_tail(&req->xfer[2], &req->msg);
 250
 251         req->xfer[3].rx_buf = &req->sample;
 252         req->xfer[3].len = 2;
 253         spi_message_add_tail(&req->xfer[3], &req->msg);
 254
 255         /* REVISIT:  take a few more samples, and compare ... */
 256
 257         /* converter in low power mode & enable PENIRQ */
 258         req->ref_off = PWRDOWN;
 259         req->xfer[4].tx_buf = &req->ref_off;
 260         req->xfer[4].len = 1;
 261         spi_message_add_tail(&req->xfer[4], &req->msg);
 262
 263         req->xfer[5].rx_buf = &req->scratch;
 264         req->xfer[5].len = 2;
 265         CS_CHANGE(req->xfer[5]);
 266         spi_message_add_tail(&req->xfer[5], &req->msg);
 267
 268         ts->irq_disabled = 1;
 269         disable_irq(spi->irq);
 270         status = spi_sync(spi, &req->msg);
 271         ts->irq_disabled = 0;
 272         enable_irq(spi->irq);
 273
 274         if (status == 0) {
 275                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 276                 status = be16_to_cpu(req->sample);
 277                 status = status >> 3;
 278                 status &= 0x0fff;
 279         }
 280
 281         kfree(req);
 282         return status;
 283 }
 284
 285 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 286
 287 #define SHOW(name, var, adjust) static ssize_t \
 288 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 289 { \
 290         struct ads7846 *ts = dev_get_drvdata(dev); \
 291         ssize_t v = ads7846_read12_ser(dev, \
 292                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 293         if (v < 0) \
 294                 return v; \
 295         return sprintf(buf, "%u\n", adjust(ts, v)); \
 296 } \
 297 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 298
 299
 300 /* Sysfs conventions report temperatures in millidegrees Celsius.
 301  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 302  * accuracy scheme without calibration data.  For now we won't try either;
 303  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 304  */
 305 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 306 {
 307         return v;
 308 }
 309
 310 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 311 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 312
 313
 314 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 315  * if we know vREF.  userspace may need to scale vAUX to match the board's
 316  * external resistors; we assume that vBATT only uses the internal ones.
 317  */
 318 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 319 {
 320         unsigned retval = v;
 321
 322         /* external resistors may scale vAUX into 0..vREF */
 323         retval *= ts->vref_mv;
 324         retval = retval >> 12;
 325         return retval;
 326 }
 327
 328 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 329 {
 330         unsigned retval = vaux_adjust(ts, v);
 331
 332         /* ads7846 has a resistor ladder to scale this signal down */
 333         if (ts->model == 7846)
 334                 retval *= 4;
 335         return retval;
 336 }
 337
 338 SHOW(in0_input, vaux, vaux_adjust)
 339 SHOW(in1_input, vbatt, vbatt_adjust)
 340
 341
 342 static struct attribute *ads7846_attributes[] = {
 343         &dev_attr_temp0.attr,
 344         &dev_attr_temp1.attr,
 345         &dev_attr_in0_input.attr,
 346         &dev_attr_in1_input.attr,
 347         NULL,
 348 };
 349
 350 static struct attribute_group ads7846_attr_group = {
 351         .attrs = ads7846_attributes,
 352 };
 353
 354 static struct attribute *ads7843_attributes[] = {
 355         &dev_attr_in0_input.attr,
 356         &dev_attr_in1_input.attr,
 357         NULL,
 358 };
 359
 360 static struct attribute_group ads7843_attr_group = {
 361         .attrs = ads7843_attributes,
 362 };
 363
 364 static struct attribute *ads7845_attributes[] = {
 365         &dev_attr_in0_input.attr,
 366         NULL,
 367 };
 368
 369 static struct attribute_group ads7845_attr_group = {
 370         .attrs = ads7845_attributes,
 371 };
 372
 373 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 374 {
 375         struct device *hwmon;
 376         int err;
 377
 378         /* hwmon sensors need a reference voltage */
 379         switch (ts->model) {
 380         case 7846:
 381                 if (!ts->vref_mv) {
 382                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 383                         ts->vref_mv = 2500;
 384                 }
 385                 break;
 386         case 7845:
 387         case 7843:
 388                 if (!ts->vref_mv) {
 389                         dev_warn(&spi->dev,
 390                                 "external vREF for ADS%d not specified\n",
 391                                 ts->model);
 392                         return 0;
 393                 }
 394                 break;
 395         }
 396
 397         /* different chips have different sensor groups */
 398         switch (ts->model) {
 399         case 7846:
 400                 ts->attr_group = &ads7846_attr_group;
 401                 break;
 402         case 7845:
 403                 ts->attr_group = &ads7845_attr_group;
 404                 break;
 405         case 7843:
 406                 ts->attr_group = &ads7843_attr_group;
 407                 break;
 408         default:
 409                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 410                 return 0;
 411         }
 412
 413         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 414         if (err)
 415                 return err;
 416
 417         hwmon = hwmon_device_register(&spi->dev);
 418         if (IS_ERR(hwmon)) {
 419                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 420                 return PTR_ERR(hwmon);
 421         }
 422
 423         ts->hwmon = hwmon;
 424         return 0;
 425 }
 426
 427 static void ads784x_hwmon_unregister(struct spi_device *spi,
 428                                      struct ads7846 *ts)
 429 {
 430         if (ts->hwmon) {
 431                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 432                 hwmon_device_unregister(ts->hwmon);
 433         }
 434 }
 435
 436 #else
 437 static inline int ads784x_hwmon_register(struct spi_device *spi,
 438                                          struct ads7846 *ts)
 439 {
 440         return 0;
 441 }
 442
 443 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 444                                             struct ads7846 *ts)
 445 {
 446 }
 447 #endif
 448
 449 static int is_pen_down(struct device *dev)
 450 {
 451         struct ads7846  *ts = dev_get_drvdata(dev);
 452
 453         return ts->pendown;
 454 }
 455
 456 static ssize_t ads7846_pen_down_show(struct device *dev,
 457                                      struct device_attribute *attr, char *buf)
 458 {
 459         return sprintf(buf, "%u\n", is_pen_down(dev));
 460 }
 461
 462 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 463
 464 static ssize_t ads7846_disable_show(struct device *dev,
 465                                      struct device_attribute *attr, char *buf)
 466 {
 467         struct ads7846  *ts = dev_get_drvdata(dev);
 468
 469         return sprintf(buf, "%u\n", ts->disabled);
 470 }
 471
 472 static ssize_t ads7846_disable_store(struct device *dev,
 473                                      struct device_attribute *attr,
 474                                      const char *buf, size_t count)
 475 {
 476         struct ads7846 *ts = dev_get_drvdata(dev);
 477         unsigned long i;
 478
 479         if (strict_strtoul(buf, 10, &i))
 480                 return -EINVAL;
 481
 482         spin_lock_irq(&ts->lock);
 483
 484         if (i)
 485                 ads7846_disable(ts);
 486         else
 487                 ads7846_enable(ts);
 488
 489         spin_unlock_irq(&ts->lock);
 490
 491         return count;
 492 }
 493
 494 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 495
 496 static struct attribute *ads784x_attributes[] = {
 497         &dev_attr_pen_down.attr,
 498         &dev_attr_disable.attr,
 499         NULL,
 500 };
 501
 502 static struct attribute_group ads784x_attr_group = {
 503         .attrs = ads784x_attributes,
 504 };
 505
 506 /*--------------------------------------------------------------------------*/
 507
 508 static int get_pendown_state(struct ads7846 *ts)
 509 {
 510         if (ts->get_pendown_state)
 511                 return ts->get_pendown_state();
 512
 513         return !gpio_get_value(ts->gpio_pendown);
 514 }
 515
 516 static void null_wait_for_sync(void)
 517 {
 518 }
 519
 520 /*
 521  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 522  * to retrieve touchscreen status.
 523  *
 524  * The SPI transfer completion callback does the real work.  It reports
 525  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 526  */
 527
 528 static void ads7846_rx(void *ads)
 529 {
 530         struct ads7846          *ts = ads;
 531         struct ads7846_packet   *packet = ts->packet;
 532         unsigned                Rt;
 533         u16                     x, y, z1, z2;
 534
 535         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 536          * on-the-wire format as part of debouncing to get stable readings.
 537          */
 538         x = packet->tc.x;
 539         y = packet->tc.y;
 540         z1 = packet->tc.z1;
 541         z2 = packet->tc.z2;
 542
 543         /* range filtering */
 544         if (x == MAX_12BIT)
 545                 x = 0;
 546
 547         if (ts->model == 7843) {
 548                 Rt = ts->pressure_max / 2;
 549         } else if (likely(x && z1)) {
 550                 /* compute touch pressure resistance using equation #2 */
 551                 Rt = z2;
 552                 Rt -= z1;
 553                 Rt *= x;
 554                 Rt *= ts->x_plate_ohms;
 555                 Rt /= z1;
 556                 Rt = (Rt + 2047) >> 12;
 557         } else {
 558                 Rt = 0;
 559         }
 560
 561         /* Sample found inconsistent by debouncing or pressure is beyond
 562          * the maximum. Don't report it to user space, repeat at least
 563          * once more the measurement
 564          */
 565         if (packet->tc.ignore || Rt > ts->pressure_max) {
 566 #ifdef VERBOSE
 567                 pr_debug("%s: ignored %d pressure %d\n",
 568                         dev_name(&ts->spi->dev), packet->tc.ignore, Rt);
 569 #endif
 570                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 571                               HRTIMER_MODE_REL);
 572                 return;
 573         }
 574
 575         /* Maybe check the pendown state before reporting. This discards
 576          * false readings when the pen is lifted.
 577          */
 578         if (ts->penirq_recheck_delay_usecs) {
 579                 udelay(ts->penirq_recheck_delay_usecs);
 580                 if (!get_pendown_state(ts))
 581                         Rt = 0;
 582         }
 583
 584         /* NOTE: We can't rely on the pressure to determine the pen down
 585          * state, even this controller has a pressure sensor.  The pressure
 586          * value can fluctuate for quite a while after lifting the pen and
 587          * in some cases may not even settle at the expected value.
 588          *
 589          * The only safe way to check for the pen up condition is in the
 590          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 591          */
 592         if (Rt) {
 593                 struct input_dev *input = ts->input;
 594
 595                 if (!ts->pendown) {
 596                         input_report_key(input, BTN_TOUCH, 1);
 597                         ts->pendown = 1;
 598 #ifdef VERBOSE
 599                         dev_dbg(&ts->spi->dev, "DOWN\n");
 600 #endif
 601                 }
 602                 input_report_abs(input, ABS_X, x);
 603                 input_report_abs(input, ABS_Y, y);
 604                 input_report_abs(input, ABS_PRESSURE, Rt);
 605
 606                 input_sync(input);
 607 #ifdef VERBOSE
 608                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 609 #endif
 610         }
 611
 612         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 613                         HRTIMER_MODE_REL);
 614 }
 615
 616 static int ads7846_debounce(void *ads, int data_idx, int *val)
 617 {
 618         struct ads7846          *ts = ads;
 619
 620         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 621                 /* Start over collecting consistent readings. */
 622                 ts->read_rep = 0;
 623                 /* Repeat it, if this was the first read or the read
 624                  * wasn't consistent enough. */
 625                 if (ts->read_cnt < ts->debounce_max) {
 626                         ts->last_read = *val;
 627                         ts->read_cnt++;
 628                         return ADS7846_FILTER_REPEAT;
 629                 } else {
 630                         /* Maximum number of debouncing reached and still
 631                          * not enough number of consistent readings. Abort
 632                          * the whole sample, repeat it in the next sampling
 633                          * period.
 634                          */
 635                         ts->read_cnt = 0;
 636                         return ADS7846_FILTER_IGNORE;
 637                 }
 638         } else {
 639                 if (++ts->read_rep > ts->debounce_rep) {
 640                         /* Got a good reading for this coordinate,
 641                          * go for the next one. */
 642                         ts->read_cnt = 0;
 643                         ts->read_rep = 0;
 644                         return ADS7846_FILTER_OK;
 645                 } else {
 646                         /* Read more values that are consistent. */
 647                         ts->read_cnt++;
 648                         return ADS7846_FILTER_REPEAT;
 649                 }
 650         }
 651 }
 652
 653 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 654 {
 655         return ADS7846_FILTER_OK;
 656 }
 657
 658 static void ads7846_rx_val(void *ads)
 659 {
 660         struct ads7846 *ts = ads;
 661         struct ads7846_packet *packet = ts->packet;
 662         struct spi_message *m;
 663         struct spi_transfer *t;
 664         int val;
 665         int action;
 666         int status;
 667
 668         m = &ts->msg[ts->msg_idx];
 669         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 670
 671         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 672          * built from two 8 bit values written msb-first.
 673          */
 674         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 675
 676         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 677         switch (action) {
 678         case ADS7846_FILTER_REPEAT:
 679                 break;
 680         case ADS7846_FILTER_IGNORE:
 681                 packet->tc.ignore = 1;
 682                 /* Last message will contain ads7846_rx() as the
 683                  * completion function.
 684                  */
 685                 m = ts->last_msg;
 686                 break;
 687         case ADS7846_FILTER_OK:
 688                 *(u16 *)t->rx_buf = val;
 689                 packet->tc.ignore = 0;
 690                 m = &ts->msg[++ts->msg_idx];
 691                 break;
 692         default:
 693                 BUG();
 694         }
 695         ts->wait_for_sync();
 696         status = spi_async(ts->spi, m);
 697         if (status)
 698                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 699                                 status);
 700 }
 701
 702 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 703 {
 704         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 705         int             status = 0;
 706
 707         spin_lock(&ts->lock);
 708
 709         if (unlikely(!get_pendown_state(ts) ||
 710                      device_suspended(&ts->spi->dev))) {
 711                 if (ts->pendown) {
 712                         struct input_dev *input = ts->input;
 713
 714                         input_report_key(input, BTN_TOUCH, 0);
 715                         input_report_abs(input, ABS_PRESSURE, 0);
 716                         input_sync(input);
 717
 718                         ts->pendown = 0;
 719 #ifdef VERBOSE
 720                         dev_dbg(&ts->spi->dev, "UP\n");
 721 #endif
 722                 }
 723
 724                 /* measurement cycle ended */
 725                 if (!device_suspended(&ts->spi->dev)) {
 726                         ts->irq_disabled = 0;
 727                         enable_irq(ts->spi->irq);
 728                 }
 729                 ts->pending = 0;
 730         } else {
 731                 /* pen is still down, continue with the measurement */
 732                 ts->msg_idx = 0;
 733                 ts->wait_for_sync();
 734                 status = spi_async(ts->spi, &ts->msg[0]);
 735                 if (status)
 736                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 737         }
 738
 739         spin_unlock(&ts->lock);
 740         return HRTIMER_NORESTART;
 741 }
 742
 743 static irqreturn_t ads7846_irq(int irq, void *handle)
 744 {
 745         struct ads7846 *ts = handle;
 746         unsigned long flags;
 747
 748         spin_lock_irqsave(&ts->lock, flags);
 749         if (likely(get_pendown_state(ts))) {
 750                 if (!ts->irq_disabled) {
 751                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 752                          * like the other dispatchers:  it will report IRQs
 753                          * even after they've been disabled.  We work around
 754                          * that here.  (The "generic irq" framework may help...)
 755                          */
 756                         ts->irq_disabled = 1;
 757                         disable_irq_nosync(ts->spi->irq);
 758                         ts->pending = 1;
 759                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 760                                         HRTIMER_MODE_REL);
 761                 }
 762         }
 763         spin_unlock_irqrestore(&ts->lock, flags);
 764
 765         return IRQ_HANDLED;
 766 }
 767
 768 /*--------------------------------------------------------------------------*/
 769
 770 /* Must be called with ts->lock held */
 771 static void ads7846_disable(struct ads7846 *ts)
 772 {
 773         if (ts->disabled)
 774                 return;
 775
 776         ts->disabled = 1;
 777
 778         /* are we waiting for IRQ, or polling? */
 779         if (!ts->pending) {
 780                 ts->irq_disabled = 1;
 781                 disable_irq(ts->spi->irq);
 782         } else {
 783                 /* the timer will run at least once more, and
 784                  * leave everything in a clean state, IRQ disabled
 785                  */
 786                 while (ts->pending) {
 787                         spin_unlock_irq(&ts->lock);
 788                         msleep(1);
 789                         spin_lock_irq(&ts->lock);
 790                 }
 791         }
 792
 793         /* we know the chip's in lowpower mode since we always
 794          * leave it that way after every request
 795          */
 796 }
 797
 798 /* Must be called with ts->lock held */
 799 static void ads7846_enable(struct ads7846 *ts)
 800 {
 801         if (!ts->disabled)
 802                 return;
 803
 804         ts->disabled = 0;
 805         ts->irq_disabled = 0;
 806         enable_irq(ts->spi->irq);
 807 }
 808
 809 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 810 {
 811         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 812
 813         spin_lock_irq(&ts->lock);
 814
 815         ts->is_suspended = 1;
 816         ads7846_disable(ts);
 817
 818         spin_unlock_irq(&ts->lock);
 819
 820         return 0;
 821
 822 }
 823
 824 static int ads7846_resume(struct spi_device *spi)
 825 {
 826         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 827
 828         spin_lock_irq(&ts->lock);
 829
 830         ts->is_suspended = 0;
 831         ads7846_enable(ts);
 832
 833         spin_unlock_irq(&ts->lock);
 834
 835         return 0;
 836 }
 837
 838 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 839 {
 840         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 841         int err;
 842
 843         /* REVISIT when the irq can be triggered active-low, or if for some
 844          * reason the touchscreen isn't hooked up, we don't need to access
 845          * the pendown state.
 846          */
 847         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
 848                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 849                 return -EINVAL;
 850         }
 851
 852         if (pdata->get_pendown_state) {
 853                 ts->get_pendown_state = pdata->get_pendown_state;
 854                 return 0;
 855         }
 856
 857         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 858         if (err) {
 859                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 860                                 pdata->gpio_pendown);
 861                 return err;
 862         }
 863
 864         ts->gpio_pendown = pdata->gpio_pendown;
 865         return 0;
 866 }
 867
 868 static int __devinit ads7846_probe(struct spi_device *spi)
 869 {
 870         struct ads7846                  *ts;
 871         struct ads7846_packet           *packet;
 872         struct input_dev                *input_dev;
 873         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 874         struct spi_message              *m;
 875         struct spi_transfer             *x;
 876         int                             vref;
 877         int                             err;
 878
 879         if (!spi->irq) {
 880                 dev_dbg(&spi->dev, "no IRQ?\n");
 881                 return -ENODEV;
 882         }
 883
 884         if (!pdata) {
 885                 dev_dbg(&spi->dev, "no platform data?\n");
 886                 return -ENODEV;
 887         }
 888
 889         /* don't exceed max specified sample rate */
 890         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 891                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 892                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 893                 return -EINVAL;
 894         }
 895
 896         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 897          * that even if the hardware can do that, the SPI controller driver
 898          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 899          */
 900         spi->bits_per_word = 8;
 901         spi->mode = SPI_MODE_0;
 902         err = spi_setup(spi);
 903         if (err < 0)
 904                 return err;
 905
 906         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 907         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
 908         input_dev = input_allocate_device();
 909         if (!ts || !packet || !input_dev) {
 910                 err = -ENOMEM;
 911                 goto err_free_mem;
 912         }
 913
 914         dev_set_drvdata(&spi->dev, ts);
 915
 916         ts->packet = packet;
 917         ts->spi = spi;
 918         ts->input = input_dev;
 919         ts->vref_mv = pdata->vref_mv;
 920
 921         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 922         ts->timer.function = ads7846_timer;
 923
 924         spin_lock_init(&ts->lock);
 925
 926         ts->model = pdata->model ? : 7846;
 927         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 928         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 929         ts->pressure_max = pdata->pressure_max ? : ~0;
 930
 931         if (pdata->filter != NULL) {
 932                 if (pdata->filter_init != NULL) {
 933                         err = pdata->filter_init(pdata, &ts->filter_data);
 934                         if (err < 0)
 935                                 goto err_free_mem;
 936                 }
 937                 ts->filter = pdata->filter;
 938                 ts->filter_cleanup = pdata->filter_cleanup;
 939         } else if (pdata->debounce_max) {
 940                 ts->debounce_max = pdata->debounce_max;
 941                 if (ts->debounce_max < 2)
 942                         ts->debounce_max = 2;
 943                 ts->debounce_tol = pdata->debounce_tol;
 944                 ts->debounce_rep = pdata->debounce_rep;
 945                 ts->filter = ads7846_debounce;
 946                 ts->filter_data = ts;
 947         } else
 948                 ts->filter = ads7846_no_filter;
 949
 950         err = setup_pendown(spi, ts);
 951         if (err)
 952                 goto err_cleanup_filter;
 953
 954         if (pdata->penirq_recheck_delay_usecs)
 955                 ts->penirq_recheck_delay_usecs =
 956                                 pdata->penirq_recheck_delay_usecs;
 957
 958         ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
 959
 960         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
 961
 962         input_dev->name = "ADS784x Touchscreen";
 963         input_dev->phys = ts->phys;
 964         input_dev->dev.parent = &spi->dev;
 965
 966         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 967         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 968         input_set_abs_params(input_dev, ABS_X,
 969                         pdata->x_min ? : 0,
 970                         pdata->x_max ? : MAX_12BIT,
 971                         0, 0);
 972         input_set_abs_params(input_dev, ABS_Y,
 973                         pdata->y_min ? : 0,
 974                         pdata->y_max ? : MAX_12BIT,
 975                         0, 0);
 976         input_set_abs_params(input_dev, ABS_PRESSURE,
 977                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 978
 979         vref = pdata->keep_vref_on;
 980
 981         /* set up the transfers to read touchscreen state; this assumes we
 982          * use formula #2 for pressure, not #3.
 983          */
 984         m = &ts->msg[0];
 985         x = ts->xfer;
 986
 987         spi_message_init(m);
 988
 989         /* y- still on; turn on only y+ (and ADC) */
 990         packet->read_y = READ_Y(vref);
 991         x->tx_buf = &packet->read_y;
 992         x->len = 1;
 993         spi_message_add_tail(x, m);
 994
 995         x++;
 996         x->rx_buf = &packet->tc.y;
 997         x->len = 2;
 998         spi_message_add_tail(x, m);
 999
1000         /* the first sample after switching drivers can be low quality;
1001          * optionally discard it, using a second one after the signals
1002          * have had enough time to stabilize.
1003          */
1004         if (pdata->settle_delay_usecs) {
1005                 x->delay_usecs = pdata->settle_delay_usecs;
1006
1007                 x++;
1008                 x->tx_buf = &packet->read_y;
1009                 x->len = 1;
1010                 spi_message_add_tail(x, m);
1011
1012                 x++;
1013                 x->rx_buf = &packet->tc.y;
1014                 x->len = 2;
1015                 spi_message_add_tail(x, m);
1016         }
1017
1018         m->complete = ads7846_rx_val;
1019         m->context = ts;
1020
1021         m++;
1022         spi_message_init(m);
1023
1024         /* turn y- off, x+ on, then leave in lowpower */
1025         x++;
1026         packet->read_x = READ_X(vref);
1027         x->tx_buf = &packet->read_x;
1028         x->len = 1;
1029         spi_message_add_tail(x, m);
1030
1031         x++;
1032         x->rx_buf = &packet->tc.x;
1033         x->len = 2;
1034         spi_message_add_tail(x, m);
1035
1036         /* ... maybe discard first sample ... */
1037         if (pdata->settle_delay_usecs) {
1038                 x->delay_usecs = pdata->settle_delay_usecs;
1039
1040                 x++;
1041                 x->tx_buf = &packet->read_x;
1042                 x->len = 1;
1043                 spi_message_add_tail(x, m);
1044
1045                 x++;
1046                 x->rx_buf = &packet->tc.x;
1047                 x->len = 2;
1048                 spi_message_add_tail(x, m);
1049         }
1050
1051         m->complete = ads7846_rx_val;
1052         m->context = ts;
1053
1054         /* turn y+ off, x- on; we'll use formula #2 */
1055         if (ts->model == 7846) {
1056                 m++;
1057                 spi_message_init(m);
1058
1059                 x++;
1060                 packet->read_z1 = READ_Z1(vref);
1061                 x->tx_buf = &packet->read_z1;
1062                 x->len = 1;
1063                 spi_message_add_tail(x, m);
1064
1065                 x++;
1066                 x->rx_buf = &packet->tc.z1;
1067                 x->len = 2;
1068                 spi_message_add_tail(x, m);
1069
1070                 /* ... maybe discard first sample ... */
1071                 if (pdata->settle_delay_usecs) {
1072                         x->delay_usecs = pdata->settle_delay_usecs;
1073
1074                         x++;
1075                         x->tx_buf = &packet->read_z1;
1076                         x->len = 1;
1077                         spi_message_add_tail(x, m);
1078
1079                         x++;
1080                         x->rx_buf = &packet->tc.z1;
1081                         x->len = 2;
1082                         spi_message_add_tail(x, m);
1083                 }
1084
1085                 m->complete = ads7846_rx_val;
1086                 m->context = ts;
1087
1088                 m++;
1089                 spi_message_init(m);
1090
1091                 x++;
1092                 packet->read_z2 = READ_Z2(vref);
1093                 x->tx_buf = &packet->read_z2;
1094                 x->len = 1;
1095                 spi_message_add_tail(x, m);
1096
1097                 x++;
1098                 x->rx_buf = &packet->tc.z2;
1099                 x->len = 2;
1100                 spi_message_add_tail(x, m);
1101
1102                 /* ... maybe discard first sample ... */
1103                 if (pdata->settle_delay_usecs) {
1104                         x->delay_usecs = pdata->settle_delay_usecs;
1105
1106                         x++;
1107                         x->tx_buf = &packet->read_z2;
1108                         x->len = 1;
1109                         spi_message_add_tail(x, m);
1110
1111                         x++;
1112                         x->rx_buf = &packet->tc.z2;
1113                         x->len = 2;
1114                         spi_message_add_tail(x, m);
1115                 }
1116
1117                 m->complete = ads7846_rx_val;
1118                 m->context = ts;
1119         }
1120
1121         /* power down */
1122         m++;
1123         spi_message_init(m);
1124
1125         x++;
1126         packet->pwrdown = PWRDOWN;
1127         x->tx_buf = &packet->pwrdown;
1128         x->len = 1;
1129         spi_message_add_tail(x, m);
1130
1131         x++;
1132         x->rx_buf = &packet->dummy;
1133         x->len = 2;
1134         CS_CHANGE(*x);
1135         spi_message_add_tail(x, m);
1136
1137         m->complete = ads7846_rx;
1138         m->context = ts;
1139
1140         ts->last_msg = m;
1141
1142         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1143                         spi->dev.driver->name, ts)) {
1144                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1145                 err = -EBUSY;
1146                 goto err_free_gpio;
1147         }
1148
1149         err = ads784x_hwmon_register(spi, ts);
1150         if (err)
1151                 goto err_free_irq;
1152
1153         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1154
1155         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1156          * the touchscreen, in case it's not connected.
1157          */
1158         (void) ads7846_read12_ser(&spi->dev,
1159                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1160
1161         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1162         if (err)
1163                 goto err_remove_hwmon;
1164
1165         err = input_register_device(input_dev);
1166         if (err)
1167                 goto err_remove_attr_group;
1168
1169         return 0;
1170
1171  err_remove_attr_group:
1172         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1173  err_remove_hwmon:
1174         ads784x_hwmon_unregister(spi, ts);
1175  err_free_irq:
1176         free_irq(spi->irq, ts);
1177  err_free_gpio:
1178         if (ts->gpio_pendown != -1)
1179                 gpio_free(ts->gpio_pendown);
1180  err_cleanup_filter:
1181         if (ts->filter_cleanup)
1182                 ts->filter_cleanup(ts->filter_data);
1183  err_free_mem:
1184         input_free_device(input_dev);
1185         kfree(packet);
1186         kfree(ts);
1187         return err;
1188 }
1189
1190 static int __devexit ads7846_remove(struct spi_device *spi)
1191 {
1192         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1193
1194         ads784x_hwmon_unregister(spi, ts);
1195         input_unregister_device(ts->input);
1196
1197         ads7846_suspend(spi, PMSG_SUSPEND);
1198
1199         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1200
1201         free_irq(ts->spi->irq, ts);
1202         /* suspend left the IRQ disabled */
1203         enable_irq(ts->spi->irq);
1204
1205         if (ts->gpio_pendown != -1)
1206                 gpio_free(ts->gpio_pendown);
1207
1208         if (ts->filter_cleanup)
1209                 ts->filter_cleanup(ts->filter_data);
1210
1211         kfree(ts->packet);
1212         kfree(ts);
1213
1214         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1215         return 0;
1216 }
1217
1218 static struct spi_driver ads7846_driver = {
1219         .driver = {
1220                 .name   = "ads7846",
1221                 .bus    = &spi_bus_type,
1222                 .owner  = THIS_MODULE,
1223         },
1224         .probe          = ads7846_probe,
1225         .remove         = __devexit_p(ads7846_remove),
1226         .suspend        = ads7846_suspend,
1227         .resume         = ads7846_resume,
1228 };
1229
1230 static int __init ads7846_init(void)
1231 {
1232         return spi_register_driver(&ads7846_driver);
1233 }
1234 module_init(ads7846_init);
1235
1236 static void __exit ads7846_exit(void)
1237 {
1238         spi_unregister_driver(&ads7846_driver);
1239 }
1240 module_exit(ads7846_exit);
1241
1242 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1243 MODULE_LICENSE("GPL");