drivers/input/touchscreen/ads7846.c

   1 /*
   2  * ADS7846 based touchscreen and sensor driver
   3  *
   4  * Copyright (c) 2005 David Brownell
   5  * Copyright (c) 2006 Nokia Corporation
   6  * Various changes: Imre Deak <imre.deak@nokia.com>
   7  *
   8  * Using code from:
   9  *  - corgi_ts.c
  10  *      Copyright (C) 2004-2005 Richard Purdie
  11  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  12  *      Copyright (C) 2002 MontaVista Software
  13  *      Copyright (C) 2004 Texas Instruments
  14  *      Copyright (C) 2005 Dirk Behme
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License version 2 as
  18  *  published by the Free Software Foundation.
  19  */
  20 #include <linux/hwmon.h>
  21 #include <linux/init.h>
  22 #include <linux/err.h>
  23 #include <linux/delay.h>
  24 #include <linux/input.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/slab.h>
  27 #include <linux/spi/spi.h>
  28 #include <linux/spi/ads7846.h>
  29 #include <asm/irq.h>
  30
  31
  32 /*
  33  * This code has been heavily tested on a Nokia 770, and lightly
  34  * tested on other ads7846 devices (OSK/Mistral, Lubbock).
  35  * TSC2046 is just newer ads7846 silicon.
  36  * Support for ads7843 tested on Atmel at91sam926x-EK.
  37  * Support for ads7845 has only been stubbed in.
  38  *
  39  * IRQ handling needs a workaround because of a shortcoming in handling
  40  * edge triggered IRQs on some platforms like the OMAP1/2. These
  41  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  42  * have to maintain our own SW IRQ disabled status. This should be
  43  * removed as soon as the affected platform's IRQ handling is fixed.
  44  *
  45  * app note sbaa036 talks in more detail about accurate sampling...
  46  * that ought to help in situations like LCDs inducing noise (which
  47  * can also be helped by using synch signals) and more generally.
  48  * This driver tries to utilize the measures described in the app
  49  * note. The strength of filtering can be set in the board-* specific
  50  * files.
  51  */
  52
  53 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  54 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  55
  56 /* this driver doesn't aim at the peak continuous sample rate */
  57 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  58
  59 struct ts_event {
  60         /* For portability, we can't read 12 bit values using SPI (which
  61          * would make the controller deliver them as native byteorder u16
  62          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  63          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  64          */
  65         u16     x;
  66         u16     y;
  67         u16     z1, z2;
  68         int     ignore;
  69 };
  70
  71 struct ads7846 {
  72         struct input_dev        *input;
  73         char                    phys[32];
  74
  75         struct spi_device       *spi;
  76
  77 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  78         struct attribute_group  *attr_group;
  79         struct device           *hwmon;
  80 #endif
  81
  82         u16                     model;
  83         u16                     vref_delay_usecs;
  84         u16                     x_plate_ohms;
  85         u16                     pressure_max;
  86
  87         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  88         u16                     dummy;          /* for the pwrdown read */
  89         struct ts_event         tc;
  90
  91         struct spi_transfer     xfer[18];
  92         struct spi_message      msg[5];
  93         struct spi_message      *last_msg;
  94         int                     msg_idx;
  95         int                     read_cnt;
  96         int                     read_rep;
  97         int                     last_read;
  98
  99         u16                     debounce_max;
 100         u16                     debounce_tol;
 101         u16                     debounce_rep;
 102
 103         u16                     penirq_recheck_delay_usecs;
 104
 105         spinlock_t              lock;
 106         struct hrtimer          timer;
 107         unsigned                pendown:1;      /* P: lock */
 108         unsigned                pending:1;      /* P: lock */
 109 // FIXME remove "irq_disabled"
 110         unsigned                irq_disabled:1; /* P: lock */
 111         unsigned                disabled:1;
 112         unsigned                is_suspended:1;
 113
 114         int                     (*filter)(void *data, int data_idx, int *val);
 115         void                    *filter_data;
 116         void                    (*filter_cleanup)(void *data);
 117         int                     (*get_pendown_state)(void);
 118 };
 119
 120 /* leave chip selected when we're done, for quicker re-select? */
 121 #if     0
 122 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 123 #else
 124 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 125 #endif
 126
 127 /*--------------------------------------------------------------------------*/
 128
 129 /* The ADS7846 has touchscreen and other sensors.
 130  * Earlier ads784x chips are somewhat compatible.
 131  */
 132 #define ADS_START               (1 << 7)
 133 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 134 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 135 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 136 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 137 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 138 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 139 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 140 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 141 #define ADS_8_BIT               (1 << 3)
 142 #define ADS_12_BIT              (0 << 3)
 143 #define ADS_SER                 (1 << 2)        /* non-differential */
 144 #define ADS_DFR                 (0 << 2)        /* differential */
 145 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 146 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 147 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 148 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 149
 150 #define MAX_12BIT       ((1<<12)-1)
 151
 152 /* leave ADC powered up (disables penirq) between differential samples */
 153 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 154         | ADS_12_BIT | ADS_DFR | \
 155         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 156
 157 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 158 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 159 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 160
 161 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 162 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 163
 164 /* single-ended samples need to first power up reference voltage;
 165  * we leave both ADC and VREF powered
 166  */
 167 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 168         | ADS_12_BIT | ADS_SER)
 169
 170 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 171 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 172
 173 /*--------------------------------------------------------------------------*/
 174
 175 /*
 176  * Non-touchscreen sensors only use single-ended conversions.
 177  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 178  * ads7846 lets that pin be unconnected, to use internal vREF.
 179  */
 180 static unsigned vREF_mV;
 181 module_param(vREF_mV, uint, 0);
 182 MODULE_PARM_DESC(vREF_mV, "external vREF voltage, in milliVolts");
 183
 184 struct ser_req {
 185         u8                      ref_on;
 186         u8                      command;
 187         u8                      ref_off;
 188         u16                     scratch;
 189         __be16                  sample;
 190         struct spi_message      msg;
 191         struct spi_transfer     xfer[6];
 192 };
 193
 194 static void ads7846_enable(struct ads7846 *ts);
 195 static void ads7846_disable(struct ads7846 *ts);
 196
 197 static int device_suspended(struct device *dev)
 198 {
 199         struct ads7846 *ts = dev_get_drvdata(dev);
 200         return ts->is_suspended || ts->disabled;
 201 }
 202
 203 static int ads7846_read12_ser(struct device *dev, unsigned command)
 204 {
 205         struct spi_device       *spi = to_spi_device(dev);
 206         struct ads7846          *ts = dev_get_drvdata(dev);
 207         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 208         int                     status;
 209         int                     uninitialized_var(sample);
 210         int                     use_internal;
 211
 212         if (!req)
 213                 return -ENOMEM;
 214
 215         spi_message_init(&req->msg);
 216
 217         /* FIXME boards with ads7846 might use external vref instead ... */
 218         use_internal = (ts->model == 7846);
 219
 220         /* maybe turn on internal vREF, and let it settle */
 221         if (use_internal) {
 222                 req->ref_on = REF_ON;
 223                 req->xfer[0].tx_buf = &req->ref_on;
 224                 req->xfer[0].len = 1;
 225                 spi_message_add_tail(&req->xfer[0], &req->msg);
 226
 227                 req->xfer[1].rx_buf = &req->scratch;
 228                 req->xfer[1].len = 2;
 229
 230                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 231                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 232                 spi_message_add_tail(&req->xfer[1], &req->msg);
 233         }
 234
 235         /* take sample */
 236         req->command = (u8) command;
 237         req->xfer[2].tx_buf = &req->command;
 238         req->xfer[2].len = 1;
 239         spi_message_add_tail(&req->xfer[2], &req->msg);
 240
 241         req->xfer[3].rx_buf = &req->sample;
 242         req->xfer[3].len = 2;
 243         spi_message_add_tail(&req->xfer[3], &req->msg);
 244
 245         /* REVISIT:  take a few more samples, and compare ... */
 246
 247         /* converter in low power mode & enable PENIRQ */
 248         req->ref_off = PWRDOWN;
 249         req->xfer[4].tx_buf = &req->ref_off;
 250         req->xfer[4].len = 1;
 251         spi_message_add_tail(&req->xfer[4], &req->msg);
 252
 253         req->xfer[5].rx_buf = &req->scratch;
 254         req->xfer[5].len = 2;
 255         CS_CHANGE(req->xfer[5]);
 256         spi_message_add_tail(&req->xfer[5], &req->msg);
 257
 258         ts->irq_disabled = 1;
 259         disable_irq(spi->irq);
 260         status = spi_sync(spi, &req->msg);
 261         ts->irq_disabled = 0;
 262         enable_irq(spi->irq);
 263
 264         if (status == 0) {
 265                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 266                 sample = be16_to_cpu(req->sample);
 267                 sample = sample >> 3;
 268                 sample &= 0x0fff;
 269         }
 270
 271         kfree(req);
 272         return status ? status : sample;
 273 }
 274
 275 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 276
 277 #define SHOW(name, var, adjust) static ssize_t \
 278 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 279 { \
 280         struct ads7846 *ts = dev_get_drvdata(dev); \
 281         ssize_t v = ads7846_read12_ser(dev, \
 282                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 283         if (v < 0) \
 284                 return v; \
 285         return sprintf(buf, "%u\n", adjust(ts, v)); \
 286 } \
 287 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 288
 289
 290 /* Sysfs conventions report temperatures in millidegrees Celcius.
 291  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 292  * accuracy scheme without calibration data.  For now we won't try either;
 293  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 294  */
 295 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 296 {
 297         return v;
 298 }
 299
 300 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 301 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 302
 303
 304 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 305  * if we know vREF.  userspace may need to scale vAUX to match the board's
 306  * external resistors; we assume that vBATT only uses the internal ones.
 307  */
 308 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 309 {
 310         unsigned retval = v;
 311
 312         /* external resistors may scale vAUX into 0..vREF */
 313         retval *= vREF_mV;
 314         retval = retval >> 12;
 315         return retval;
 316 }
 317
 318 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 319 {
 320         unsigned retval = vaux_adjust(ts, v);
 321
 322         /* ads7846 has a resistor ladder to scale this signal down */
 323         if (ts->model == 7846)
 324                 retval *= 4;
 325         return retval;
 326 }
 327
 328 SHOW(in0_input, vaux, vaux_adjust)
 329 SHOW(in1_input, vbatt, vbatt_adjust)
 330
 331
 332 static struct attribute *ads7846_attributes[] = {
 333         &dev_attr_temp0.attr,
 334         &dev_attr_temp1.attr,
 335         &dev_attr_in0_input.attr,
 336         &dev_attr_in1_input.attr,
 337         NULL,
 338 };
 339
 340 static struct attribute_group ads7846_attr_group = {
 341         .attrs = ads7846_attributes,
 342 };
 343
 344 static struct attribute *ads7843_attributes[] = {
 345         &dev_attr_in0_input.attr,
 346         &dev_attr_in1_input.attr,
 347         NULL,
 348 };
 349
 350 static struct attribute_group ads7843_attr_group = {
 351         .attrs = ads7843_attributes,
 352 };
 353
 354 static struct attribute *ads7845_attributes[] = {
 355         &dev_attr_in0_input.attr,
 356         NULL,
 357 };
 358
 359 static struct attribute_group ads7845_attr_group = {
 360         .attrs = ads7845_attributes,
 361 };
 362
 363 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 364 {
 365         struct device *hwmon;
 366         int err;
 367
 368         /* hwmon sensors need a reference voltage */
 369         switch (ts->model) {
 370         case 7846:
 371                 if (!vREF_mV) {
 372                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 373                         vREF_mV = 2500;
 374                 }
 375                 break;
 376         case 7845:
 377         case 7843:
 378                 if (!vREF_mV) {
 379                         dev_warn(&spi->dev,
 380                                 "external vREF for ADS%d not specified\n",
 381                                 ts->model);
 382                         return 0;
 383                 }
 384                 break;
 385         }
 386
 387         /* different chips have different sensor groups */
 388         switch (ts->model) {
 389         case 7846:
 390                 ts->attr_group = &ads7846_attr_group;
 391                 break;
 392         case 7845:
 393                 ts->attr_group = &ads7845_attr_group;
 394                 break;
 395         case 7843:
 396                 ts->attr_group = &ads7843_attr_group;
 397                 break;
 398         default:
 399                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 400                 return 0;
 401         }
 402
 403         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 404         if (err)
 405                 return err;
 406
 407         hwmon = hwmon_device_register(&spi->dev);
 408         if (IS_ERR(hwmon)) {
 409                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 410                 return PTR_ERR(hwmon);
 411         }
 412
 413         ts->hwmon = hwmon;
 414         return 0;
 415 }
 416
 417 static void ads784x_hwmon_unregister(struct spi_device *spi,
 418                                      struct ads7846 *ts)
 419 {
 420         if (ts->hwmon) {
 421                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 422                 hwmon_device_unregister(ts->hwmon);
 423         }
 424 }
 425
 426 #else
 427 static inline int ads784x_hwmon_register(struct spi_device *spi,
 428                                          struct ads7846 *ts)
 429 {
 430         return 0;
 431 }
 432
 433 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 434                                             struct ads7846 *ts)
 435 {
 436 }
 437 #endif
 438
 439 static int is_pen_down(struct device *dev)
 440 {
 441         struct ads7846  *ts = dev_get_drvdata(dev);
 442
 443         return ts->pendown;
 444 }
 445
 446 static ssize_t ads7846_pen_down_show(struct device *dev,
 447                                      struct device_attribute *attr, char *buf)
 448 {
 449         return sprintf(buf, "%u\n", is_pen_down(dev));
 450 }
 451
 452 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 453
 454 static ssize_t ads7846_disable_show(struct device *dev,
 455                                      struct device_attribute *attr, char *buf)
 456 {
 457         struct ads7846  *ts = dev_get_drvdata(dev);
 458
 459         return sprintf(buf, "%u\n", ts->disabled);
 460 }
 461
 462 static ssize_t ads7846_disable_store(struct device *dev,
 463                                      struct device_attribute *attr,
 464                                      const char *buf, size_t count)
 465 {
 466         struct ads7846 *ts = dev_get_drvdata(dev);
 467         char *endp;
 468         int i;
 469
 470         i = simple_strtoul(buf, &endp, 10);
 471         spin_lock_irq(&ts->lock);
 472
 473         if (i)
 474                 ads7846_disable(ts);
 475         else
 476                 ads7846_enable(ts);
 477
 478         spin_unlock_irq(&ts->lock);
 479
 480         return count;
 481 }
 482
 483 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 484
 485 static struct attribute *ads784x_attributes[] = {
 486         &dev_attr_pen_down.attr,
 487         &dev_attr_disable.attr,
 488         NULL,
 489 };
 490
 491 static struct attribute_group ads784x_attr_group = {
 492         .attrs = ads784x_attributes,
 493 };
 494
 495 /*--------------------------------------------------------------------------*/
 496
 497 /*
 498  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 499  * to retrieve touchscreen status.
 500  *
 501  * The SPI transfer completion callback does the real work.  It reports
 502  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 503  */
 504
 505 static void ads7846_rx(void *ads)
 506 {
 507         struct ads7846          *ts = ads;
 508         unsigned                Rt;
 509         u16                     x, y, z1, z2;
 510
 511         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 512          * on-the-wire format as part of debouncing to get stable readings.
 513          */
 514         x = ts->tc.x;
 515         y = ts->tc.y;
 516         z1 = ts->tc.z1;
 517         z2 = ts->tc.z2;
 518
 519         /* range filtering */
 520         if (x == MAX_12BIT)
 521                 x = 0;
 522
 523         if (likely(x && z1)) {
 524                 /* compute touch pressure resistance using equation #2 */
 525                 Rt = z2;
 526                 Rt -= z1;
 527                 Rt *= x;
 528                 Rt *= ts->x_plate_ohms;
 529                 Rt /= z1;
 530                 Rt = (Rt + 2047) >> 12;
 531         } else
 532                 Rt = 0;
 533
 534         if (ts->model == 7843)
 535                 Rt = ts->pressure_max / 2;
 536
 537         /* Sample found inconsistent by debouncing or pressure is beyond
 538          * the maximum. Don't report it to user space, repeat at least
 539          * once more the measurement
 540          */
 541         if (ts->tc.ignore || Rt > ts->pressure_max) {
 542 #ifdef VERBOSE
 543                 pr_debug("%s: ignored %d pressure %d\n",
 544                         ts->spi->dev.bus_id, ts->tc.ignore, Rt);
 545 #endif
 546                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 547                               HRTIMER_MODE_REL);
 548                 return;
 549         }
 550
 551         /* Maybe check the pendown state before reporting. This discards
 552          * false readings when the pen is lifted.
 553          */
 554         if (ts->penirq_recheck_delay_usecs) {
 555                 udelay(ts->penirq_recheck_delay_usecs);
 556                 if (!ts->get_pendown_state())
 557                         Rt = 0;
 558         }
 559
 560         /* NOTE: We can't rely on the pressure to determine the pen down
 561          * state, even this controller has a pressure sensor.  The pressure
 562          * value can fluctuate for quite a while after lifting the pen and
 563          * in some cases may not even settle at the expected value.
 564          *
 565          * The only safe way to check for the pen up condition is in the
 566          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 567          */
 568         if (Rt) {
 569                 struct input_dev *input = ts->input;
 570
 571                 if (!ts->pendown) {
 572                         input_report_key(input, BTN_TOUCH, 1);
 573                         ts->pendown = 1;
 574 #ifdef VERBOSE
 575                         dev_dbg(&ts->spi->dev, "DOWN\n");
 576 #endif
 577                 }
 578                 input_report_abs(input, ABS_X, x);
 579                 input_report_abs(input, ABS_Y, y);
 580                 input_report_abs(input, ABS_PRESSURE, Rt);
 581
 582                 input_sync(input);
 583 #ifdef VERBOSE
 584                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 585 #endif
 586         }
 587
 588         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 589                         HRTIMER_MODE_REL);
 590 }
 591
 592 static int ads7846_debounce(void *ads, int data_idx, int *val)
 593 {
 594         struct ads7846          *ts = ads;
 595
 596         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 597                 /* Start over collecting consistent readings. */
 598                 ts->read_rep = 0;
 599                 /* Repeat it, if this was the first read or the read
 600                  * wasn't consistent enough. */
 601                 if (ts->read_cnt < ts->debounce_max) {
 602                         ts->last_read = *val;
 603                         ts->read_cnt++;
 604                         return ADS7846_FILTER_REPEAT;
 605                 } else {
 606                         /* Maximum number of debouncing reached and still
 607                          * not enough number of consistent readings. Abort
 608                          * the whole sample, repeat it in the next sampling
 609                          * period.
 610                          */
 611                         ts->read_cnt = 0;
 612                         return ADS7846_FILTER_IGNORE;
 613                 }
 614         } else {
 615                 if (++ts->read_rep > ts->debounce_rep) {
 616                         /* Got a good reading for this coordinate,
 617                          * go for the next one. */
 618                         ts->read_cnt = 0;
 619                         ts->read_rep = 0;
 620                         return ADS7846_FILTER_OK;
 621                 } else {
 622                         /* Read more values that are consistent. */
 623                         ts->read_cnt++;
 624                         return ADS7846_FILTER_REPEAT;
 625                 }
 626         }
 627 }
 628
 629 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 630 {
 631         return ADS7846_FILTER_OK;
 632 }
 633
 634 static void ads7846_rx_val(void *ads)
 635 {
 636         struct ads7846 *ts = ads;
 637         struct spi_message *m;
 638         struct spi_transfer *t;
 639         u16 *rx_val;
 640         int val;
 641         int action;
 642         int status;
 643
 644         m = &ts->msg[ts->msg_idx];
 645         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 646         rx_val = t->rx_buf;
 647
 648         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 649          * built from two 8 bit values written msb-first.
 650          */
 651         val = be16_to_cpu(*rx_val) >> 3;
 652
 653         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 654         switch (action) {
 655         case ADS7846_FILTER_REPEAT:
 656                 break;
 657         case ADS7846_FILTER_IGNORE:
 658                 ts->tc.ignore = 1;
 659                 /* Last message will contain ads7846_rx() as the
 660                  * completion function.
 661                  */
 662                 m = ts->last_msg;
 663                 break;
 664         case ADS7846_FILTER_OK:
 665                 *rx_val = val;
 666                 ts->tc.ignore = 0;
 667                 m = &ts->msg[++ts->msg_idx];
 668                 break;
 669         default:
 670                 BUG();
 671         }
 672         status = spi_async(ts->spi, m);
 673         if (status)
 674                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 675                                 status);
 676 }
 677
 678 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 679 {
 680         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 681         int             status = 0;
 682
 683         spin_lock_irq(&ts->lock);
 684
 685         if (unlikely(!ts->get_pendown_state() ||
 686                      device_suspended(&ts->spi->dev))) {
 687                 if (ts->pendown) {
 688                         struct input_dev *input = ts->input;
 689
 690                         input_report_key(input, BTN_TOUCH, 0);
 691                         input_report_abs(input, ABS_PRESSURE, 0);
 692                         input_sync(input);
 693
 694                         ts->pendown = 0;
 695 #ifdef VERBOSE
 696                         dev_dbg(&ts->spi->dev, "UP\n");
 697 #endif
 698                 }
 699
 700                 /* measurement cycle ended */
 701                 if (!device_suspended(&ts->spi->dev)) {
 702                         ts->irq_disabled = 0;
 703                         enable_irq(ts->spi->irq);
 704                 }
 705                 ts->pending = 0;
 706         } else {
 707                 /* pen is still down, continue with the measurement */
 708                 ts->msg_idx = 0;
 709                 status = spi_async(ts->spi, &ts->msg[0]);
 710                 if (status)
 711                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 712         }
 713
 714         spin_unlock_irq(&ts->lock);
 715         return HRTIMER_NORESTART;
 716 }
 717
 718 static irqreturn_t ads7846_irq(int irq, void *handle)
 719 {
 720         struct ads7846 *ts = handle;
 721         unsigned long flags;
 722
 723         spin_lock_irqsave(&ts->lock, flags);
 724         if (likely(ts->get_pendown_state())) {
 725                 if (!ts->irq_disabled) {
 726                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 727                          * like the other dispatchers:  it will report IRQs
 728                          * even after they've been disabled.  We work around
 729                          * that here.  (The "generic irq" framework may help...)
 730                          */
 731                         ts->irq_disabled = 1;
 732                         disable_irq(ts->spi->irq);
 733                         ts->pending = 1;
 734                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 735                                         HRTIMER_MODE_REL);
 736                 }
 737         }
 738         spin_unlock_irqrestore(&ts->lock, flags);
 739
 740         return IRQ_HANDLED;
 741 }
 742
 743 /*--------------------------------------------------------------------------*/
 744
 745 /* Must be called with ts->lock held */
 746 static void ads7846_disable(struct ads7846 *ts)
 747 {
 748         if (ts->disabled)
 749                 return;
 750
 751         ts->disabled = 1;
 752
 753         /* are we waiting for IRQ, or polling? */
 754         if (!ts->pending) {
 755                 ts->irq_disabled = 1;
 756                 disable_irq(ts->spi->irq);
 757         } else {
 758                 /* the timer will run at least once more, and
 759                  * leave everything in a clean state, IRQ disabled
 760                  */
 761                 while (ts->pending) {
 762                         spin_unlock_irq(&ts->lock);
 763                         msleep(1);
 764                         spin_lock_irq(&ts->lock);
 765                 }
 766         }
 767
 768         /* we know the chip's in lowpower mode since we always
 769          * leave it that way after every request
 770          */
 771
 772 }
 773
 774 /* Must be called with ts->lock held */
 775 static void ads7846_enable(struct ads7846 *ts)
 776 {
 777         if (!ts->disabled)
 778                 return;
 779
 780         ts->disabled = 0;
 781         ts->irq_disabled = 0;
 782         enable_irq(ts->spi->irq);
 783 }
 784
 785 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 786 {
 787         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 788
 789         spin_lock_irq(&ts->lock);
 790
 791         ts->is_suspended = 1;
 792         ads7846_disable(ts);
 793
 794         spin_unlock_irq(&ts->lock);
 795
 796         return 0;
 797
 798 }
 799
 800 static int ads7846_resume(struct spi_device *spi)
 801 {
 802         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 803
 804         spin_lock_irq(&ts->lock);
 805
 806         ts->is_suspended = 0;
 807         ads7846_enable(ts);
 808
 809         spin_unlock_irq(&ts->lock);
 810
 811         return 0;
 812 }
 813
 814 static int __devinit ads7846_probe(struct spi_device *spi)
 815 {
 816         struct ads7846                  *ts;
 817         struct input_dev                *input_dev;
 818         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 819         struct spi_message              *m;
 820         struct spi_transfer             *x;
 821         int                             vref;
 822         int                             err;
 823
 824         if (!spi->irq) {
 825                 dev_dbg(&spi->dev, "no IRQ?\n");
 826                 return -ENODEV;
 827         }
 828
 829         if (!pdata) {
 830                 dev_dbg(&spi->dev, "no platform data?\n");
 831                 return -ENODEV;
 832         }
 833
 834         /* don't exceed max specified sample rate */
 835         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 836                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 837                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 838                 return -EINVAL;
 839         }
 840
 841         /* REVISIT when the irq can be triggered active-low, or if for some
 842          * reason the touchscreen isn't hooked up, we don't need to access
 843          * the pendown state.
 844          */
 845         if (pdata->get_pendown_state == NULL) {
 846                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 847                 return -EINVAL;
 848         }
 849
 850         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 851          * that even if the hardware can do that, the SPI controller driver
 852          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 853          */
 854         spi->bits_per_word = 8;
 855         spi->mode = SPI_MODE_0;
 856         err = spi_setup(spi);
 857         if (err < 0)
 858                 return err;
 859
 860         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 861         input_dev = input_allocate_device();
 862         if (!ts || !input_dev) {
 863                 err = -ENOMEM;
 864                 goto err_free_mem;
 865         }
 866
 867         dev_set_drvdata(&spi->dev, ts);
 868
 869         ts->spi = spi;
 870         ts->input = input_dev;
 871
 872         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 873         ts->timer.function = ads7846_timer;
 874
 875         spin_lock_init(&ts->lock);
 876
 877         ts->model = pdata->model ? : 7846;
 878         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 879         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 880         ts->pressure_max = pdata->pressure_max ? : ~0;
 881
 882         if (pdata->filter != NULL) {
 883                 if (pdata->filter_init != NULL) {
 884                         err = pdata->filter_init(pdata, &ts->filter_data);
 885                         if (err < 0)
 886                                 goto err_free_mem;
 887                 }
 888                 ts->filter = pdata->filter;
 889                 ts->filter_cleanup = pdata->filter_cleanup;
 890         } else if (pdata->debounce_max) {
 891                 ts->debounce_max = pdata->debounce_max;
 892                 if (ts->debounce_max < 2)
 893                         ts->debounce_max = 2;
 894                 ts->debounce_tol = pdata->debounce_tol;
 895                 ts->debounce_rep = pdata->debounce_rep;
 896                 ts->filter = ads7846_debounce;
 897                 ts->filter_data = ts;
 898         } else
 899                 ts->filter = ads7846_no_filter;
 900         ts->get_pendown_state = pdata->get_pendown_state;
 901
 902         if (pdata->penirq_recheck_delay_usecs)
 903                 ts->penirq_recheck_delay_usecs =
 904                                 pdata->penirq_recheck_delay_usecs;
 905
 906         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 907
 908         input_dev->name = "ADS784x Touchscreen";
 909         input_dev->phys = ts->phys;
 910         input_dev->dev.parent = &spi->dev;
 911
 912         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 913         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 914         input_set_abs_params(input_dev, ABS_X,
 915                         pdata->x_min ? : 0,
 916                         pdata->x_max ? : MAX_12BIT,
 917                         0, 0);
 918         input_set_abs_params(input_dev, ABS_Y,
 919                         pdata->y_min ? : 0,
 920                         pdata->y_max ? : MAX_12BIT,
 921                         0, 0);
 922         input_set_abs_params(input_dev, ABS_PRESSURE,
 923                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 924
 925         vref = pdata->keep_vref_on;
 926
 927         /* set up the transfers to read touchscreen state; this assumes we
 928          * use formula #2 for pressure, not #3.
 929          */
 930         m = &ts->msg[0];
 931         x = ts->xfer;
 932
 933         spi_message_init(m);
 934
 935         /* y- still on; turn on only y+ (and ADC) */
 936         ts->read_y = READ_Y(vref);
 937         x->tx_buf = &ts->read_y;
 938         x->len = 1;
 939         spi_message_add_tail(x, m);
 940
 941         x++;
 942         x->rx_buf = &ts->tc.y;
 943         x->len = 2;
 944         spi_message_add_tail(x, m);
 945
 946         /* the first sample after switching drivers can be low quality;
 947          * optionally discard it, using a second one after the signals
 948          * have had enough time to stabilize.
 949          */
 950         if (pdata->settle_delay_usecs) {
 951                 x->delay_usecs = pdata->settle_delay_usecs;
 952
 953                 x++;
 954                 x->tx_buf = &ts->read_y;
 955                 x->len = 1;
 956                 spi_message_add_tail(x, m);
 957
 958                 x++;
 959                 x->rx_buf = &ts->tc.y;
 960                 x->len = 2;
 961                 spi_message_add_tail(x, m);
 962         }
 963
 964         m->complete = ads7846_rx_val;
 965         m->context = ts;
 966
 967         m++;
 968         spi_message_init(m);
 969
 970         /* turn y- off, x+ on, then leave in lowpower */
 971         x++;
 972         ts->read_x = READ_X(vref);
 973         x->tx_buf = &ts->read_x;
 974         x->len = 1;
 975         spi_message_add_tail(x, m);
 976
 977         x++;
 978         x->rx_buf = &ts->tc.x;
 979         x->len = 2;
 980         spi_message_add_tail(x, m);
 981
 982         /* ... maybe discard first sample ... */
 983         if (pdata->settle_delay_usecs) {
 984                 x->delay_usecs = pdata->settle_delay_usecs;
 985
 986                 x++;
 987                 x->tx_buf = &ts->read_x;
 988                 x->len = 1;
 989                 spi_message_add_tail(x, m);
 990
 991                 x++;
 992                 x->rx_buf = &ts->tc.x;
 993                 x->len = 2;
 994                 spi_message_add_tail(x, m);
 995         }
 996
 997         m->complete = ads7846_rx_val;
 998         m->context = ts;
 999
1000         /* turn y+ off, x- on; we'll use formula #2 */
1001         if (ts->model == 7846) {
1002                 m++;
1003                 spi_message_init(m);
1004
1005                 x++;
1006                 ts->read_z1 = READ_Z1(vref);
1007                 x->tx_buf = &ts->read_z1;
1008                 x->len = 1;
1009                 spi_message_add_tail(x, m);
1010
1011                 x++;
1012                 x->rx_buf = &ts->tc.z1;
1013                 x->len = 2;
1014                 spi_message_add_tail(x, m);
1015
1016                 /* ... maybe discard first sample ... */
1017                 if (pdata->settle_delay_usecs) {
1018                         x->delay_usecs = pdata->settle_delay_usecs;
1019
1020                         x++;
1021                         x->tx_buf = &ts->read_z1;
1022                         x->len = 1;
1023                         spi_message_add_tail(x, m);
1024
1025                         x++;
1026                         x->rx_buf = &ts->tc.z1;
1027                         x->len = 2;
1028                         spi_message_add_tail(x, m);
1029                 }
1030
1031                 m->complete = ads7846_rx_val;
1032                 m->context = ts;
1033
1034                 m++;
1035                 spi_message_init(m);
1036
1037                 x++;
1038                 ts->read_z2 = READ_Z2(vref);
1039                 x->tx_buf = &ts->read_z2;
1040                 x->len = 1;
1041                 spi_message_add_tail(x, m);
1042
1043                 x++;
1044                 x->rx_buf = &ts->tc.z2;
1045                 x->len = 2;
1046                 spi_message_add_tail(x, m);
1047
1048                 /* ... maybe discard first sample ... */
1049                 if (pdata->settle_delay_usecs) {
1050                         x->delay_usecs = pdata->settle_delay_usecs;
1051
1052                         x++;
1053                         x->tx_buf = &ts->read_z2;
1054                         x->len = 1;
1055                         spi_message_add_tail(x, m);
1056
1057                         x++;
1058                         x->rx_buf = &ts->tc.z2;
1059                         x->len = 2;
1060                         spi_message_add_tail(x, m);
1061                 }
1062
1063                 m->complete = ads7846_rx_val;
1064                 m->context = ts;
1065         }
1066
1067         /* power down */
1068         m++;
1069         spi_message_init(m);
1070
1071         x++;
1072         ts->pwrdown = PWRDOWN;
1073         x->tx_buf = &ts->pwrdown;
1074         x->len = 1;
1075         spi_message_add_tail(x, m);
1076
1077         x++;
1078         x->rx_buf = &ts->dummy;
1079         x->len = 2;
1080         CS_CHANGE(*x);
1081         spi_message_add_tail(x, m);
1082
1083         m->complete = ads7846_rx;
1084         m->context = ts;
1085
1086         ts->last_msg = m;
1087
1088         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1089                         spi->dev.driver->name, ts)) {
1090                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1091                 err = -EBUSY;
1092                 goto err_cleanup_filter;
1093         }
1094
1095         err = ads784x_hwmon_register(spi, ts);
1096         if (err)
1097                 goto err_free_irq;
1098
1099         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1100
1101         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1102          * the touchscreen, in case it's not connected.
1103          */
1104         (void) ads7846_read12_ser(&spi->dev,
1105                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1106
1107         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1108         if (err)
1109                 goto err_remove_hwmon;
1110
1111         err = input_register_device(input_dev);
1112         if (err)
1113                 goto err_remove_attr_group;
1114
1115         return 0;
1116
1117  err_remove_attr_group:
1118         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1119  err_remove_hwmon:
1120         ads784x_hwmon_unregister(spi, ts);
1121  err_free_irq:
1122         free_irq(spi->irq, ts);
1123  err_cleanup_filter:
1124         if (ts->filter_cleanup)
1125                 ts->filter_cleanup(ts->filter_data);
1126  err_free_mem:
1127         input_free_device(input_dev);
1128         kfree(ts);
1129         return err;
1130 }
1131
1132 static int __devexit ads7846_remove(struct spi_device *spi)
1133 {
1134         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1135
1136         ads784x_hwmon_unregister(spi, ts);
1137         input_unregister_device(ts->input);
1138
1139         ads7846_suspend(spi, PMSG_SUSPEND);
1140
1141         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1142
1143         free_irq(ts->spi->irq, ts);
1144         /* suspend left the IRQ disabled */
1145         enable_irq(ts->spi->irq);
1146
1147         if (ts->filter_cleanup)
1148                 ts->filter_cleanup(ts->filter_data);
1149
1150         kfree(ts);
1151
1152         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1153         return 0;
1154 }
1155
1156 static struct spi_driver ads7846_driver = {
1157         .driver = {
1158                 .name   = "ads7846",
1159                 .bus    = &spi_bus_type,
1160                 .owner  = THIS_MODULE,
1161         },
1162         .probe          = ads7846_probe,
1163         .remove         = __devexit_p(ads7846_remove),
1164         .suspend        = ads7846_suspend,
1165         .resume         = ads7846_resume,
1166 };
1167
1168 static int __init ads7846_init(void)
1169 {
1170         return spi_register_driver(&ads7846_driver);
1171 }
1172 module_init(ads7846_init);
1173
1174 static void __exit ads7846_exit(void)
1175 {
1176         spi_unregister_driver(&ads7846_driver);
1177 }
1178 module_exit(ads7846_exit);
1179
1180 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1181 MODULE_LICENSE("GPL");