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
 132 /* leave chip selected when we're done, for quicker re-select? */
 133 #if     0
 134 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 135 #else
 136 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 137 #endif
 138
 139 /*--------------------------------------------------------------------------*/
 140
 141 /* The ADS7846 has touchscreen and other sensors.
 142  * Earlier ads784x chips are somewhat compatible.
 143  */
 144 #define ADS_START               (1 << 7)
 145 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 146 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 147 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 148 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 149 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 150 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 151 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 152 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 153 #define ADS_8_BIT               (1 << 3)
 154 #define ADS_12_BIT              (0 << 3)
 155 #define ADS_SER                 (1 << 2)        /* non-differential */
 156 #define ADS_DFR                 (0 << 2)        /* differential */
 157 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 158 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 159 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 160 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 161
 162 #define MAX_12BIT       ((1<<12)-1)
 163
 164 /* leave ADC powered up (disables penirq) between differential samples */
 165 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 166         | ADS_12_BIT | ADS_DFR | \
 167         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 168
 169 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 170 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 171 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 172
 173 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 174 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 175
 176 /* single-ended samples need to first power up reference voltage;
 177  * we leave both ADC and VREF powered
 178  */
 179 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 180         | ADS_12_BIT | ADS_SER)
 181
 182 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 183 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 184
 185 /*--------------------------------------------------------------------------*/
 186
 187 /*
 188  * Non-touchscreen sensors only use single-ended conversions.
 189  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 190  * ads7846 lets that pin be unconnected, to use internal vREF.
 191  */
 192
 193 struct ser_req {
 194         u8                      ref_on;
 195         u8                      command;
 196         u8                      ref_off;
 197         u16                     scratch;
 198         __be16                  sample;
 199         struct spi_message      msg;
 200         struct spi_transfer     xfer[6];
 201 };
 202
 203 static void ads7846_enable(struct ads7846 *ts);
 204 static void ads7846_disable(struct ads7846 *ts);
 205
 206 static int device_suspended(struct device *dev)
 207 {
 208         struct ads7846 *ts = dev_get_drvdata(dev);
 209         return ts->is_suspended || ts->disabled;
 210 }
 211
 212 static int ads7846_read12_ser(struct device *dev, unsigned command)
 213 {
 214         struct spi_device       *spi = to_spi_device(dev);
 215         struct ads7846          *ts = dev_get_drvdata(dev);
 216         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 217         int                     status;
 218         int                     use_internal;
 219
 220         if (!req)
 221                 return -ENOMEM;
 222
 223         spi_message_init(&req->msg);
 224
 225         /* FIXME boards with ads7846 might use external vref instead ... */
 226         use_internal = (ts->model == 7846);
 227
 228         /* maybe turn on internal vREF, and let it settle */
 229         if (use_internal) {
 230                 req->ref_on = REF_ON;
 231                 req->xfer[0].tx_buf = &req->ref_on;
 232                 req->xfer[0].len = 1;
 233                 spi_message_add_tail(&req->xfer[0], &req->msg);
 234
 235                 req->xfer[1].rx_buf = &req->scratch;
 236                 req->xfer[1].len = 2;
 237
 238                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 239                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 240                 spi_message_add_tail(&req->xfer[1], &req->msg);
 241         }
 242
 243         /* take sample */
 244         req->command = (u8) command;
 245         req->xfer[2].tx_buf = &req->command;
 246         req->xfer[2].len = 1;
 247         spi_message_add_tail(&req->xfer[2], &req->msg);
 248
 249         req->xfer[3].rx_buf = &req->sample;
 250         req->xfer[3].len = 2;
 251         spi_message_add_tail(&req->xfer[3], &req->msg);
 252
 253         /* REVISIT:  take a few more samples, and compare ... */
 254
 255         /* converter in low power mode & enable PENIRQ */
 256         req->ref_off = PWRDOWN;
 257         req->xfer[4].tx_buf = &req->ref_off;
 258         req->xfer[4].len = 1;
 259         spi_message_add_tail(&req->xfer[4], &req->msg);
 260
 261         req->xfer[5].rx_buf = &req->scratch;
 262         req->xfer[5].len = 2;
 263         CS_CHANGE(req->xfer[5]);
 264         spi_message_add_tail(&req->xfer[5], &req->msg);
 265
 266         ts->irq_disabled = 1;
 267         disable_irq(spi->irq);
 268         status = spi_sync(spi, &req->msg);
 269         ts->irq_disabled = 0;
 270         enable_irq(spi->irq);
 271
 272         if (status == 0) {
 273                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 274                 status = be16_to_cpu(req->sample);
 275                 status = status >> 3;
 276                 status &= 0x0fff;
 277         }
 278
 279         kfree(req);
 280         return status;
 281 }
 282
 283 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 284
 285 #define SHOW(name, var, adjust) static ssize_t \
 286 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 287 { \
 288         struct ads7846 *ts = dev_get_drvdata(dev); \
 289         ssize_t v = ads7846_read12_ser(dev, \
 290                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 291         if (v < 0) \
 292                 return v; \
 293         return sprintf(buf, "%u\n", adjust(ts, v)); \
 294 } \
 295 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 296
 297
 298 /* Sysfs conventions report temperatures in millidegrees Celcius.
 299  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 300  * accuracy scheme without calibration data.  For now we won't try either;
 301  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 302  */
 303 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 304 {
 305         return v;
 306 }
 307
 308 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 309 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 310
 311
 312 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 313  * if we know vREF.  userspace may need to scale vAUX to match the board's
 314  * external resistors; we assume that vBATT only uses the internal ones.
 315  */
 316 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 317 {
 318         unsigned retval = v;
 319
 320         /* external resistors may scale vAUX into 0..vREF */
 321         retval *= ts->vref_mv;
 322         retval = retval >> 12;
 323         return retval;
 324 }
 325
 326 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 327 {
 328         unsigned retval = vaux_adjust(ts, v);
 329
 330         /* ads7846 has a resistor ladder to scale this signal down */
 331         if (ts->model == 7846)
 332                 retval *= 4;
 333         return retval;
 334 }
 335
 336 SHOW(in0_input, vaux, vaux_adjust)
 337 SHOW(in1_input, vbatt, vbatt_adjust)
 338
 339
 340 static struct attribute *ads7846_attributes[] = {
 341         &dev_attr_temp0.attr,
 342         &dev_attr_temp1.attr,
 343         &dev_attr_in0_input.attr,
 344         &dev_attr_in1_input.attr,
 345         NULL,
 346 };
 347
 348 static struct attribute_group ads7846_attr_group = {
 349         .attrs = ads7846_attributes,
 350 };
 351
 352 static struct attribute *ads7843_attributes[] = {
 353         &dev_attr_in0_input.attr,
 354         &dev_attr_in1_input.attr,
 355         NULL,
 356 };
 357
 358 static struct attribute_group ads7843_attr_group = {
 359         .attrs = ads7843_attributes,
 360 };
 361
 362 static struct attribute *ads7845_attributes[] = {
 363         &dev_attr_in0_input.attr,
 364         NULL,
 365 };
 366
 367 static struct attribute_group ads7845_attr_group = {
 368         .attrs = ads7845_attributes,
 369 };
 370
 371 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 372 {
 373         struct device *hwmon;
 374         int err;
 375
 376         /* hwmon sensors need a reference voltage */
 377         switch (ts->model) {
 378         case 7846:
 379                 if (!ts->vref_mv) {
 380                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 381                         ts->vref_mv = 2500;
 382                 }
 383                 break;
 384         case 7845:
 385         case 7843:
 386                 if (!ts->vref_mv) {
 387                         dev_warn(&spi->dev,
 388                                 "external vREF for ADS%d not specified\n",
 389                                 ts->model);
 390                         return 0;
 391                 }
 392                 break;
 393         }
 394
 395         /* different chips have different sensor groups */
 396         switch (ts->model) {
 397         case 7846:
 398                 ts->attr_group = &ads7846_attr_group;
 399                 break;
 400         case 7845:
 401                 ts->attr_group = &ads7845_attr_group;
 402                 break;
 403         case 7843:
 404                 ts->attr_group = &ads7843_attr_group;
 405                 break;
 406         default:
 407                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 408                 return 0;
 409         }
 410
 411         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 412         if (err)
 413                 return err;
 414
 415         hwmon = hwmon_device_register(&spi->dev);
 416         if (IS_ERR(hwmon)) {
 417                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 418                 return PTR_ERR(hwmon);
 419         }
 420
 421         ts->hwmon = hwmon;
 422         return 0;
 423 }
 424
 425 static void ads784x_hwmon_unregister(struct spi_device *spi,
 426                                      struct ads7846 *ts)
 427 {
 428         if (ts->hwmon) {
 429                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 430                 hwmon_device_unregister(ts->hwmon);
 431         }
 432 }
 433
 434 #else
 435 static inline int ads784x_hwmon_register(struct spi_device *spi,
 436                                          struct ads7846 *ts)
 437 {
 438         return 0;
 439 }
 440
 441 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 442                                             struct ads7846 *ts)
 443 {
 444 }
 445 #endif
 446
 447 static int is_pen_down(struct device *dev)
 448 {
 449         struct ads7846  *ts = dev_get_drvdata(dev);
 450
 451         return ts->pendown;
 452 }
 453
 454 static ssize_t ads7846_pen_down_show(struct device *dev,
 455                                      struct device_attribute *attr, char *buf)
 456 {
 457         return sprintf(buf, "%u\n", is_pen_down(dev));
 458 }
 459
 460 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 461
 462 static ssize_t ads7846_disable_show(struct device *dev,
 463                                      struct device_attribute *attr, char *buf)
 464 {
 465         struct ads7846  *ts = dev_get_drvdata(dev);
 466
 467         return sprintf(buf, "%u\n", ts->disabled);
 468 }
 469
 470 static ssize_t ads7846_disable_store(struct device *dev,
 471                                      struct device_attribute *attr,
 472                                      const char *buf, size_t count)
 473 {
 474         struct ads7846 *ts = dev_get_drvdata(dev);
 475         unsigned long i;
 476
 477         if (strict_strtoul(buf, 10, &i))
 478                 return -EINVAL;
 479
 480         spin_lock_irq(&ts->lock);
 481
 482         if (i)
 483                 ads7846_disable(ts);
 484         else
 485                 ads7846_enable(ts);
 486
 487         spin_unlock_irq(&ts->lock);
 488
 489         return count;
 490 }
 491
 492 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 493
 494 static struct attribute *ads784x_attributes[] = {
 495         &dev_attr_pen_down.attr,
 496         &dev_attr_disable.attr,
 497         NULL,
 498 };
 499
 500 static struct attribute_group ads784x_attr_group = {
 501         .attrs = ads784x_attributes,
 502 };
 503
 504 /*--------------------------------------------------------------------------*/
 505
 506 static int get_pendown_state(struct ads7846 *ts)
 507 {
 508         if (ts->get_pendown_state)
 509                 return ts->get_pendown_state();
 510
 511         return !gpio_get_value(ts->gpio_pendown);
 512 }
 513
 514 /*
 515  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 516  * to retrieve touchscreen status.
 517  *
 518  * The SPI transfer completion callback does the real work.  It reports
 519  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 520  */
 521
 522 static void ads7846_rx(void *ads)
 523 {
 524         struct ads7846          *ts = ads;
 525         struct ads7846_packet   *packet = ts->packet;
 526         unsigned                Rt;
 527         u16                     x, y, z1, z2;
 528
 529         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 530          * on-the-wire format as part of debouncing to get stable readings.
 531          */
 532         x = packet->tc.x;
 533         y = packet->tc.y;
 534         z1 = packet->tc.z1;
 535         z2 = packet->tc.z2;
 536
 537         /* range filtering */
 538         if (x == MAX_12BIT)
 539                 x = 0;
 540
 541         if (ts->model == 7843) {
 542                 Rt = ts->pressure_max / 2;
 543         } else if (likely(x && z1)) {
 544                 /* compute touch pressure resistance using equation #2 */
 545                 Rt = z2;
 546                 Rt -= z1;
 547                 Rt *= x;
 548                 Rt *= ts->x_plate_ohms;
 549                 Rt /= z1;
 550                 Rt = (Rt + 2047) >> 12;
 551         } else {
 552                 Rt = 0;
 553         }
 554
 555         /* Sample found inconsistent by debouncing or pressure is beyond
 556          * the maximum. Don't report it to user space, repeat at least
 557          * once more the measurement
 558          */
 559         if (packet->tc.ignore || Rt > ts->pressure_max) {
 560 #ifdef VERBOSE
 561                 pr_debug("%s: ignored %d pressure %d\n",
 562                         dev_name(&ts->spi->dev), packet->tc.ignore, Rt);
 563 #endif
 564                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 565                               HRTIMER_MODE_REL);
 566                 return;
 567         }
 568
 569         /* Maybe check the pendown state before reporting. This discards
 570          * false readings when the pen is lifted.
 571          */
 572         if (ts->penirq_recheck_delay_usecs) {
 573                 udelay(ts->penirq_recheck_delay_usecs);
 574                 if (!get_pendown_state(ts))
 575                         Rt = 0;
 576         }
 577
 578         /* NOTE: We can't rely on the pressure to determine the pen down
 579          * state, even this controller has a pressure sensor.  The pressure
 580          * value can fluctuate for quite a while after lifting the pen and
 581          * in some cases may not even settle at the expected value.
 582          *
 583          * The only safe way to check for the pen up condition is in the
 584          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 585          */
 586         if (Rt) {
 587                 struct input_dev *input = ts->input;
 588
 589                 if (!ts->pendown) {
 590                         input_report_key(input, BTN_TOUCH, 1);
 591                         ts->pendown = 1;
 592 #ifdef VERBOSE
 593                         dev_dbg(&ts->spi->dev, "DOWN\n");
 594 #endif
 595                 }
 596                 input_report_abs(input, ABS_X, x);
 597                 input_report_abs(input, ABS_Y, y);
 598                 input_report_abs(input, ABS_PRESSURE, Rt);
 599
 600                 input_sync(input);
 601 #ifdef VERBOSE
 602                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 603 #endif
 604         }
 605
 606         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 607                         HRTIMER_MODE_REL);
 608 }
 609
 610 static int ads7846_debounce(void *ads, int data_idx, int *val)
 611 {
 612         struct ads7846          *ts = ads;
 613
 614         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 615                 /* Start over collecting consistent readings. */
 616                 ts->read_rep = 0;
 617                 /* Repeat it, if this was the first read or the read
 618                  * wasn't consistent enough. */
 619                 if (ts->read_cnt < ts->debounce_max) {
 620                         ts->last_read = *val;
 621                         ts->read_cnt++;
 622                         return ADS7846_FILTER_REPEAT;
 623                 } else {
 624                         /* Maximum number of debouncing reached and still
 625                          * not enough number of consistent readings. Abort
 626                          * the whole sample, repeat it in the next sampling
 627                          * period.
 628                          */
 629                         ts->read_cnt = 0;
 630                         return ADS7846_FILTER_IGNORE;
 631                 }
 632         } else {
 633                 if (++ts->read_rep > ts->debounce_rep) {
 634                         /* Got a good reading for this coordinate,
 635                          * go for the next one. */
 636                         ts->read_cnt = 0;
 637                         ts->read_rep = 0;
 638                         return ADS7846_FILTER_OK;
 639                 } else {
 640                         /* Read more values that are consistent. */
 641                         ts->read_cnt++;
 642                         return ADS7846_FILTER_REPEAT;
 643                 }
 644         }
 645 }
 646
 647 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 648 {
 649         return ADS7846_FILTER_OK;
 650 }
 651
 652 static void ads7846_rx_val(void *ads)
 653 {
 654         struct ads7846 *ts = ads;
 655         struct ads7846_packet *packet = ts->packet;
 656         struct spi_message *m;
 657         struct spi_transfer *t;
 658         int val;
 659         int action;
 660         int status;
 661
 662         m = &ts->msg[ts->msg_idx];
 663         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 664
 665         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 666          * built from two 8 bit values written msb-first.
 667          */
 668         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 669
 670         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 671         switch (action) {
 672         case ADS7846_FILTER_REPEAT:
 673                 break;
 674         case ADS7846_FILTER_IGNORE:
 675                 packet->tc.ignore = 1;
 676                 /* Last message will contain ads7846_rx() as the
 677                  * completion function.
 678                  */
 679                 m = ts->last_msg;
 680                 break;
 681         case ADS7846_FILTER_OK:
 682                 *(u16 *)t->rx_buf = val;
 683                 packet->tc.ignore = 0;
 684                 m = &ts->msg[++ts->msg_idx];
 685                 break;
 686         default:
 687                 BUG();
 688         }
 689         status = spi_async(ts->spi, m);
 690         if (status)
 691                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 692                                 status);
 693 }
 694
 695 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 696 {
 697         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 698         int             status = 0;
 699
 700         spin_lock(&ts->lock);
 701
 702         if (unlikely(!get_pendown_state(ts) ||
 703                      device_suspended(&ts->spi->dev))) {
 704                 if (ts->pendown) {
 705                         struct input_dev *input = ts->input;
 706
 707                         input_report_key(input, BTN_TOUCH, 0);
 708                         input_report_abs(input, ABS_PRESSURE, 0);
 709                         input_sync(input);
 710
 711                         ts->pendown = 0;
 712 #ifdef VERBOSE
 713                         dev_dbg(&ts->spi->dev, "UP\n");
 714 #endif
 715                 }
 716
 717                 /* measurement cycle ended */
 718                 if (!device_suspended(&ts->spi->dev)) {
 719                         ts->irq_disabled = 0;
 720                         enable_irq(ts->spi->irq);
 721                 }
 722                 ts->pending = 0;
 723         } else {
 724                 /* pen is still down, continue with the measurement */
 725                 ts->msg_idx = 0;
 726                 status = spi_async(ts->spi, &ts->msg[0]);
 727                 if (status)
 728                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 729         }
 730
 731         spin_unlock(&ts->lock);
 732         return HRTIMER_NORESTART;
 733 }
 734
 735 static irqreturn_t ads7846_irq(int irq, void *handle)
 736 {
 737         struct ads7846 *ts = handle;
 738         unsigned long flags;
 739
 740         spin_lock_irqsave(&ts->lock, flags);
 741         if (likely(get_pendown_state(ts))) {
 742                 if (!ts->irq_disabled) {
 743                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 744                          * like the other dispatchers:  it will report IRQs
 745                          * even after they've been disabled.  We work around
 746                          * that here.  (The "generic irq" framework may help...)
 747                          */
 748                         ts->irq_disabled = 1;
 749                         disable_irq(ts->spi->irq);
 750                         ts->pending = 1;
 751                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 752                                         HRTIMER_MODE_REL);
 753                 }
 754         }
 755         spin_unlock_irqrestore(&ts->lock, flags);
 756
 757         return IRQ_HANDLED;
 758 }
 759
 760 /*--------------------------------------------------------------------------*/
 761
 762 /* Must be called with ts->lock held */
 763 static void ads7846_disable(struct ads7846 *ts)
 764 {
 765         if (ts->disabled)
 766                 return;
 767
 768         ts->disabled = 1;
 769
 770         /* are we waiting for IRQ, or polling? */
 771         if (!ts->pending) {
 772                 ts->irq_disabled = 1;
 773                 disable_irq(ts->spi->irq);
 774         } else {
 775                 /* the timer will run at least once more, and
 776                  * leave everything in a clean state, IRQ disabled
 777                  */
 778                 while (ts->pending) {
 779                         spin_unlock_irq(&ts->lock);
 780                         msleep(1);
 781                         spin_lock_irq(&ts->lock);
 782                 }
 783         }
 784
 785         /* we know the chip's in lowpower mode since we always
 786          * leave it that way after every request
 787          */
 788 }
 789
 790 /* Must be called with ts->lock held */
 791 static void ads7846_enable(struct ads7846 *ts)
 792 {
 793         if (!ts->disabled)
 794                 return;
 795
 796         ts->disabled = 0;
 797         ts->irq_disabled = 0;
 798         enable_irq(ts->spi->irq);
 799 }
 800
 801 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 802 {
 803         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 804
 805         spin_lock_irq(&ts->lock);
 806
 807         ts->is_suspended = 1;
 808         ads7846_disable(ts);
 809
 810         spin_unlock_irq(&ts->lock);
 811
 812         return 0;
 813
 814 }
 815
 816 static int ads7846_resume(struct spi_device *spi)
 817 {
 818         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 819
 820         spin_lock_irq(&ts->lock);
 821
 822         ts->is_suspended = 0;
 823         ads7846_enable(ts);
 824
 825         spin_unlock_irq(&ts->lock);
 826
 827         return 0;
 828 }
 829
 830 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 831 {
 832         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 833         int err;
 834
 835         /* REVISIT when the irq can be triggered active-low, or if for some
 836          * reason the touchscreen isn't hooked up, we don't need to access
 837          * the pendown state.
 838          */
 839         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
 840                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 841                 return -EINVAL;
 842         }
 843
 844         if (pdata->get_pendown_state) {
 845                 ts->get_pendown_state = pdata->get_pendown_state;
 846                 return 0;
 847         }
 848
 849         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 850         if (err) {
 851                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 852                                 pdata->gpio_pendown);
 853                 return err;
 854         }
 855
 856         ts->gpio_pendown = pdata->gpio_pendown;
 857         return 0;
 858 }
 859
 860 static int __devinit ads7846_probe(struct spi_device *spi)
 861 {
 862         struct ads7846                  *ts;
 863         struct ads7846_packet           *packet;
 864         struct input_dev                *input_dev;
 865         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 866         struct spi_message              *m;
 867         struct spi_transfer             *x;
 868         int                             vref;
 869         int                             err;
 870
 871         if (!spi->irq) {
 872                 dev_dbg(&spi->dev, "no IRQ?\n");
 873                 return -ENODEV;
 874         }
 875
 876         if (!pdata) {
 877                 dev_dbg(&spi->dev, "no platform data?\n");
 878                 return -ENODEV;
 879         }
 880
 881         /* don't exceed max specified sample rate */
 882         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 883                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 884                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 885                 return -EINVAL;
 886         }
 887
 888         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 889          * that even if the hardware can do that, the SPI controller driver
 890          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 891          */
 892         spi->bits_per_word = 8;
 893         spi->mode = SPI_MODE_0;
 894         err = spi_setup(spi);
 895         if (err < 0)
 896                 return err;
 897
 898         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 899         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
 900         input_dev = input_allocate_device();
 901         if (!ts || !packet || !input_dev) {
 902                 err = -ENOMEM;
 903                 goto err_free_mem;
 904         }
 905
 906         dev_set_drvdata(&spi->dev, ts);
 907
 908         ts->packet = packet;
 909         ts->spi = spi;
 910         ts->input = input_dev;
 911         ts->vref_mv = pdata->vref_mv;
 912
 913         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 914         ts->timer.function = ads7846_timer;
 915
 916         spin_lock_init(&ts->lock);
 917
 918         ts->model = pdata->model ? : 7846;
 919         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 920         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 921         ts->pressure_max = pdata->pressure_max ? : ~0;
 922
 923         if (pdata->filter != NULL) {
 924                 if (pdata->filter_init != NULL) {
 925                         err = pdata->filter_init(pdata, &ts->filter_data);
 926                         if (err < 0)
 927                                 goto err_free_mem;
 928                 }
 929                 ts->filter = pdata->filter;
 930                 ts->filter_cleanup = pdata->filter_cleanup;
 931         } else if (pdata->debounce_max) {
 932                 ts->debounce_max = pdata->debounce_max;
 933                 if (ts->debounce_max < 2)
 934                         ts->debounce_max = 2;
 935                 ts->debounce_tol = pdata->debounce_tol;
 936                 ts->debounce_rep = pdata->debounce_rep;
 937                 ts->filter = ads7846_debounce;
 938                 ts->filter_data = ts;
 939         } else
 940                 ts->filter = ads7846_no_filter;
 941
 942         err = setup_pendown(spi, ts);
 943         if (err)
 944                 goto err_cleanup_filter;
 945
 946         if (pdata->penirq_recheck_delay_usecs)
 947                 ts->penirq_recheck_delay_usecs =
 948                                 pdata->penirq_recheck_delay_usecs;
 949
 950         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
 951
 952         input_dev->name = "ADS784x Touchscreen";
 953         input_dev->phys = ts->phys;
 954         input_dev->dev.parent = &spi->dev;
 955
 956         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 957         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 958         input_set_abs_params(input_dev, ABS_X,
 959                         pdata->x_min ? : 0,
 960                         pdata->x_max ? : MAX_12BIT,
 961                         0, 0);
 962         input_set_abs_params(input_dev, ABS_Y,
 963                         pdata->y_min ? : 0,
 964                         pdata->y_max ? : MAX_12BIT,
 965                         0, 0);
 966         input_set_abs_params(input_dev, ABS_PRESSURE,
 967                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 968
 969         vref = pdata->keep_vref_on;
 970
 971         /* set up the transfers to read touchscreen state; this assumes we
 972          * use formula #2 for pressure, not #3.
 973          */
 974         m = &ts->msg[0];
 975         x = ts->xfer;
 976
 977         spi_message_init(m);
 978
 979         /* y- still on; turn on only y+ (and ADC) */
 980         packet->read_y = READ_Y(vref);
 981         x->tx_buf = &packet->read_y;
 982         x->len = 1;
 983         spi_message_add_tail(x, m);
 984
 985         x++;
 986         x->rx_buf = &packet->tc.y;
 987         x->len = 2;
 988         spi_message_add_tail(x, m);
 989
 990         /* the first sample after switching drivers can be low quality;
 991          * optionally discard it, using a second one after the signals
 992          * have had enough time to stabilize.
 993          */
 994         if (pdata->settle_delay_usecs) {
 995                 x->delay_usecs = pdata->settle_delay_usecs;
 996
 997                 x++;
 998                 x->tx_buf = &packet->read_y;
 999                 x->len = 1;
1000                 spi_message_add_tail(x, m);
1001
1002                 x++;
1003                 x->rx_buf = &packet->tc.y;
1004                 x->len = 2;
1005                 spi_message_add_tail(x, m);
1006         }
1007
1008         m->complete = ads7846_rx_val;
1009         m->context = ts;
1010
1011         m++;
1012         spi_message_init(m);
1013
1014         /* turn y- off, x+ on, then leave in lowpower */
1015         x++;
1016         packet->read_x = READ_X(vref);
1017         x->tx_buf = &packet->read_x;
1018         x->len = 1;
1019         spi_message_add_tail(x, m);
1020
1021         x++;
1022         x->rx_buf = &packet->tc.x;
1023         x->len = 2;
1024         spi_message_add_tail(x, m);
1025
1026         /* ... maybe discard first sample ... */
1027         if (pdata->settle_delay_usecs) {
1028                 x->delay_usecs = pdata->settle_delay_usecs;
1029
1030                 x++;
1031                 x->tx_buf = &packet->read_x;
1032                 x->len = 1;
1033                 spi_message_add_tail(x, m);
1034
1035                 x++;
1036                 x->rx_buf = &packet->tc.x;
1037                 x->len = 2;
1038                 spi_message_add_tail(x, m);
1039         }
1040
1041         m->complete = ads7846_rx_val;
1042         m->context = ts;
1043
1044         /* turn y+ off, x- on; we'll use formula #2 */
1045         if (ts->model == 7846) {
1046                 m++;
1047                 spi_message_init(m);
1048
1049                 x++;
1050                 packet->read_z1 = READ_Z1(vref);
1051                 x->tx_buf = &packet->read_z1;
1052                 x->len = 1;
1053                 spi_message_add_tail(x, m);
1054
1055                 x++;
1056                 x->rx_buf = &packet->tc.z1;
1057                 x->len = 2;
1058                 spi_message_add_tail(x, m);
1059
1060                 /* ... maybe discard first sample ... */
1061                 if (pdata->settle_delay_usecs) {
1062                         x->delay_usecs = pdata->settle_delay_usecs;
1063
1064                         x++;
1065                         x->tx_buf = &packet->read_z1;
1066                         x->len = 1;
1067                         spi_message_add_tail(x, m);
1068
1069                         x++;
1070                         x->rx_buf = &packet->tc.z1;
1071                         x->len = 2;
1072                         spi_message_add_tail(x, m);
1073                 }
1074
1075                 m->complete = ads7846_rx_val;
1076                 m->context = ts;
1077
1078                 m++;
1079                 spi_message_init(m);
1080
1081                 x++;
1082                 packet->read_z2 = READ_Z2(vref);
1083                 x->tx_buf = &packet->read_z2;
1084                 x->len = 1;
1085                 spi_message_add_tail(x, m);
1086
1087                 x++;
1088                 x->rx_buf = &packet->tc.z2;
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_z2;
1098                         x->len = 1;
1099                         spi_message_add_tail(x, m);
1100
1101                         x++;
1102                         x->rx_buf = &packet->tc.z2;
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
1111         /* power down */
1112         m++;
1113         spi_message_init(m);
1114
1115         x++;
1116         packet->pwrdown = PWRDOWN;
1117         x->tx_buf = &packet->pwrdown;
1118         x->len = 1;
1119         spi_message_add_tail(x, m);
1120
1121         x++;
1122         x->rx_buf = &packet->dummy;
1123         x->len = 2;
1124         CS_CHANGE(*x);
1125         spi_message_add_tail(x, m);
1126
1127         m->complete = ads7846_rx;
1128         m->context = ts;
1129
1130         ts->last_msg = m;
1131
1132         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1133                         spi->dev.driver->name, ts)) {
1134                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1135                 err = -EBUSY;
1136                 goto err_free_gpio;
1137         }
1138
1139         err = ads784x_hwmon_register(spi, ts);
1140         if (err)
1141                 goto err_free_irq;
1142
1143         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1144
1145         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1146          * the touchscreen, in case it's not connected.
1147          */
1148         (void) ads7846_read12_ser(&spi->dev,
1149                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1150
1151         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1152         if (err)
1153                 goto err_remove_hwmon;
1154
1155         err = input_register_device(input_dev);
1156         if (err)
1157                 goto err_remove_attr_group;
1158
1159         return 0;
1160
1161  err_remove_attr_group:
1162         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1163  err_remove_hwmon:
1164         ads784x_hwmon_unregister(spi, ts);
1165  err_free_irq:
1166         free_irq(spi->irq, ts);
1167  err_free_gpio:
1168         if (ts->gpio_pendown != -1)
1169                 gpio_free(ts->gpio_pendown);
1170  err_cleanup_filter:
1171         if (ts->filter_cleanup)
1172                 ts->filter_cleanup(ts->filter_data);
1173  err_free_mem:
1174         input_free_device(input_dev);
1175         kfree(packet);
1176         kfree(ts);
1177         return err;
1178 }
1179
1180 static int __devexit ads7846_remove(struct spi_device *spi)
1181 {
1182         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1183
1184         ads784x_hwmon_unregister(spi, ts);
1185         input_unregister_device(ts->input);
1186
1187         ads7846_suspend(spi, PMSG_SUSPEND);
1188
1189         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1190
1191         free_irq(ts->spi->irq, ts);
1192         /* suspend left the IRQ disabled */
1193         enable_irq(ts->spi->irq);
1194
1195         if (ts->gpio_pendown != -1)
1196                 gpio_free(ts->gpio_pendown);
1197
1198         if (ts->filter_cleanup)
1199                 ts->filter_cleanup(ts->filter_data);
1200
1201         kfree(ts->packet);
1202         kfree(ts);
1203
1204         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1205         return 0;
1206 }
1207
1208 static struct spi_driver ads7846_driver = {
1209         .driver = {
1210                 .name   = "ads7846",
1211                 .bus    = &spi_bus_type,
1212                 .owner  = THIS_MODULE,
1213         },
1214         .probe          = ads7846_probe,
1215         .remove         = __devexit_p(ads7846_remove),
1216         .suspend        = ads7846_suspend,
1217         .resume         = ads7846_resume,
1218 };
1219
1220 static int __init ads7846_init(void)
1221 {
1222         return spi_register_driver(&ads7846_driver);
1223 }
1224 module_init(ads7846_init);
1225
1226 static void __exit ads7846_exit(void)
1227 {
1228         spi_unregister_driver(&ads7846_driver);
1229 }
1230 module_exit(ads7846_exit);
1231
1232 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1233 MODULE_LICENSE("GPL");