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  * This code has been heavily tested on a Nokia 770, and lightly
  34  * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
  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 /*
  72  * We allocate this separately to avoid cache line sharing issues when
  73  * driver is used with DMA-based SPI controllers (like atmel_spi) on
  74  * systems where main memory is not DMA-coherent (most non-x86 boards).
  75  */
  76 struct ads7846_packet {
  77         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  78         u16                     dummy;          /* for the pwrdown read */
  79         struct ts_event         tc;
  80 };
  81
  82 struct ads7846 {
  83         struct input_dev        *input;
  84         char                    phys[32];
  85         char                    name[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         bool                    swap_xy;
 101
 102         struct ads7846_packet   *packet;
 103
 104         struct spi_transfer     xfer[18];
 105         struct spi_message      msg[5];
 106         struct spi_message      *last_msg;
 107         int                     msg_idx;
 108         int                     read_cnt;
 109         int                     read_rep;
 110         int                     last_read;
 111
 112         u16                     debounce_max;
 113         u16                     debounce_tol;
 114         u16                     debounce_rep;
 115
 116         u16                     penirq_recheck_delay_usecs;
 117
 118         spinlock_t              lock;
 119         struct hrtimer          timer;
 120         unsigned                pendown:1;      /* P: lock */
 121         unsigned                pending:1;      /* P: lock */
 122 // FIXME remove "irq_disabled"
 123         unsigned                irq_disabled:1; /* P: lock */
 124         unsigned                disabled:1;
 125         unsigned                is_suspended:1;
 126
 127         int                     (*filter)(void *data, int data_idx, int *val);
 128         void                    *filter_data;
 129         void                    (*filter_cleanup)(void *data);
 130         int                     (*get_pendown_state)(void);
 131         int                     gpio_pendown;
 132
 133         void                    (*wait_for_sync)(void);
 134 };
 135
 136 /* leave chip selected when we're done, for quicker re-select? */
 137 #if     0
 138 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 139 #else
 140 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 141 #endif
 142
 143 /*--------------------------------------------------------------------------*/
 144
 145 /* The ADS7846 has touchscreen and other sensors.
 146  * Earlier ads784x chips are somewhat compatible.
 147  */
 148 #define ADS_START               (1 << 7)
 149 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 150 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 151 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 152 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 153 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 154 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 155 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 156 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 157 #define ADS_8_BIT               (1 << 3)
 158 #define ADS_12_BIT              (0 << 3)
 159 #define ADS_SER                 (1 << 2)        /* non-differential */
 160 #define ADS_DFR                 (0 << 2)        /* differential */
 161 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 162 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 163 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 164 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 165
 166 #define MAX_12BIT       ((1<<12)-1)
 167
 168 /* leave ADC powered up (disables penirq) between differential samples */
 169 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 170         | ADS_12_BIT | ADS_DFR | \
 171         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 172
 173 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 174 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 175 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 176
 177 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 178 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 179
 180 /* single-ended samples need to first power up reference voltage;
 181  * we leave both ADC and VREF powered
 182  */
 183 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 184         | ADS_12_BIT | ADS_SER)
 185
 186 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 187 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 188
 189 /*--------------------------------------------------------------------------*/
 190
 191 /*
 192  * Non-touchscreen sensors only use single-ended conversions.
 193  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 194  * ads7846 lets that pin be unconnected, to use internal vREF.
 195  */
 196
 197 struct ser_req {
 198         u8                      ref_on;
 199         u8                      command;
 200         u8                      ref_off;
 201         u16                     scratch;
 202         __be16                  sample;
 203         struct spi_message      msg;
 204         struct spi_transfer     xfer[6];
 205 };
 206
 207 static void ads7846_enable(struct ads7846 *ts);
 208 static void ads7846_disable(struct ads7846 *ts);
 209
 210 static int device_suspended(struct device *dev)
 211 {
 212         struct ads7846 *ts = dev_get_drvdata(dev);
 213         return ts->is_suspended || ts->disabled;
 214 }
 215
 216 static int ads7846_read12_ser(struct device *dev, unsigned command)
 217 {
 218         struct spi_device       *spi = to_spi_device(dev);
 219         struct ads7846          *ts = dev_get_drvdata(dev);
 220         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 221         int                     status;
 222         int                     use_internal;
 223
 224         if (!req)
 225                 return -ENOMEM;
 226
 227         spi_message_init(&req->msg);
 228
 229         /* FIXME boards with ads7846 might use external vref instead ... */
 230         use_internal = (ts->model == 7846);
 231
 232         /* maybe turn on internal vREF, and let it settle */
 233         if (use_internal) {
 234                 req->ref_on = REF_ON;
 235                 req->xfer[0].tx_buf = &req->ref_on;
 236                 req->xfer[0].len = 1;
 237                 spi_message_add_tail(&req->xfer[0], &req->msg);
 238
 239                 req->xfer[1].rx_buf = &req->scratch;
 240                 req->xfer[1].len = 2;
 241
 242                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 243                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 244                 spi_message_add_tail(&req->xfer[1], &req->msg);
 245         }
 246
 247         /* take sample */
 248         req->command = (u8) command;
 249         req->xfer[2].tx_buf = &req->command;
 250         req->xfer[2].len = 1;
 251         spi_message_add_tail(&req->xfer[2], &req->msg);
 252
 253         req->xfer[3].rx_buf = &req->sample;
 254         req->xfer[3].len = 2;
 255         spi_message_add_tail(&req->xfer[3], &req->msg);
 256
 257         /* REVISIT:  take a few more samples, and compare ... */
 258
 259         /* converter in low power mode & enable PENIRQ */
 260         req->ref_off = PWRDOWN;
 261         req->xfer[4].tx_buf = &req->ref_off;
 262         req->xfer[4].len = 1;
 263         spi_message_add_tail(&req->xfer[4], &req->msg);
 264
 265         req->xfer[5].rx_buf = &req->scratch;
 266         req->xfer[5].len = 2;
 267         CS_CHANGE(req->xfer[5]);
 268         spi_message_add_tail(&req->xfer[5], &req->msg);
 269
 270         ts->irq_disabled = 1;
 271         disable_irq(spi->irq);
 272         status = spi_sync(spi, &req->msg);
 273         ts->irq_disabled = 0;
 274         enable_irq(spi->irq);
 275
 276         if (status == 0) {
 277                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 278                 status = be16_to_cpu(req->sample);
 279                 status = status >> 3;
 280                 status &= 0x0fff;
 281         }
 282
 283         kfree(req);
 284         return status;
 285 }
 286
 287 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 288
 289 #define SHOW(name, var, adjust) static ssize_t \
 290 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 291 { \
 292         struct ads7846 *ts = dev_get_drvdata(dev); \
 293         ssize_t v = ads7846_read12_ser(dev, \
 294                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 295         if (v < 0) \
 296                 return v; \
 297         return sprintf(buf, "%u\n", adjust(ts, v)); \
 298 } \
 299 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 300
 301
 302 /* Sysfs conventions report temperatures in millidegrees Celsius.
 303  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 304  * accuracy scheme without calibration data.  For now we won't try either;
 305  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 306  */
 307 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 308 {
 309         return v;
 310 }
 311
 312 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 313 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 314
 315
 316 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 317  * if we know vREF.  userspace may need to scale vAUX to match the board's
 318  * external resistors; we assume that vBATT only uses the internal ones.
 319  */
 320 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 321 {
 322         unsigned retval = v;
 323
 324         /* external resistors may scale vAUX into 0..vREF */
 325         retval *= ts->vref_mv;
 326         retval = retval >> 12;
 327         return retval;
 328 }
 329
 330 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 331 {
 332         unsigned retval = vaux_adjust(ts, v);
 333
 334         /* ads7846 has a resistor ladder to scale this signal down */
 335         if (ts->model == 7846)
 336                 retval *= 4;
 337         return retval;
 338 }
 339
 340 SHOW(in0_input, vaux, vaux_adjust)
 341 SHOW(in1_input, vbatt, vbatt_adjust)
 342
 343
 344 static struct attribute *ads7846_attributes[] = {
 345         &dev_attr_temp0.attr,
 346         &dev_attr_temp1.attr,
 347         &dev_attr_in0_input.attr,
 348         &dev_attr_in1_input.attr,
 349         NULL,
 350 };
 351
 352 static struct attribute_group ads7846_attr_group = {
 353         .attrs = ads7846_attributes,
 354 };
 355
 356 static struct attribute *ads7843_attributes[] = {
 357         &dev_attr_in0_input.attr,
 358         &dev_attr_in1_input.attr,
 359         NULL,
 360 };
 361
 362 static struct attribute_group ads7843_attr_group = {
 363         .attrs = ads7843_attributes,
 364 };
 365
 366 static struct attribute *ads7845_attributes[] = {
 367         &dev_attr_in0_input.attr,
 368         NULL,
 369 };
 370
 371 static struct attribute_group ads7845_attr_group = {
 372         .attrs = ads7845_attributes,
 373 };
 374
 375 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 376 {
 377         struct device *hwmon;
 378         int err;
 379
 380         /* hwmon sensors need a reference voltage */
 381         switch (ts->model) {
 382         case 7846:
 383                 if (!ts->vref_mv) {
 384                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 385                         ts->vref_mv = 2500;
 386                 }
 387                 break;
 388         case 7845:
 389         case 7843:
 390                 if (!ts->vref_mv) {
 391                         dev_warn(&spi->dev,
 392                                 "external vREF for ADS%d not specified\n",
 393                                 ts->model);
 394                         return 0;
 395                 }
 396                 break;
 397         }
 398
 399         /* different chips have different sensor groups */
 400         switch (ts->model) {
 401         case 7846:
 402                 ts->attr_group = &ads7846_attr_group;
 403                 break;
 404         case 7845:
 405                 ts->attr_group = &ads7845_attr_group;
 406                 break;
 407         case 7843:
 408                 ts->attr_group = &ads7843_attr_group;
 409                 break;
 410         default:
 411                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 412                 return 0;
 413         }
 414
 415         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 416         if (err)
 417                 return err;
 418
 419         hwmon = hwmon_device_register(&spi->dev);
 420         if (IS_ERR(hwmon)) {
 421                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 422                 return PTR_ERR(hwmon);
 423         }
 424
 425         ts->hwmon = hwmon;
 426         return 0;
 427 }
 428
 429 static void ads784x_hwmon_unregister(struct spi_device *spi,
 430                                      struct ads7846 *ts)
 431 {
 432         if (ts->hwmon) {
 433                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 434                 hwmon_device_unregister(ts->hwmon);
 435         }
 436 }
 437
 438 #else
 439 static inline int ads784x_hwmon_register(struct spi_device *spi,
 440                                          struct ads7846 *ts)
 441 {
 442         return 0;
 443 }
 444
 445 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 446                                             struct ads7846 *ts)
 447 {
 448 }
 449 #endif
 450
 451 static int is_pen_down(struct device *dev)
 452 {
 453         struct ads7846  *ts = dev_get_drvdata(dev);
 454
 455         return ts->pendown;
 456 }
 457
 458 static ssize_t ads7846_pen_down_show(struct device *dev,
 459                                      struct device_attribute *attr, char *buf)
 460 {
 461         return sprintf(buf, "%u\n", is_pen_down(dev));
 462 }
 463
 464 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 465
 466 static ssize_t ads7846_disable_show(struct device *dev,
 467                                      struct device_attribute *attr, char *buf)
 468 {
 469         struct ads7846  *ts = dev_get_drvdata(dev);
 470
 471         return sprintf(buf, "%u\n", ts->disabled);
 472 }
 473
 474 static ssize_t ads7846_disable_store(struct device *dev,
 475                                      struct device_attribute *attr,
 476                                      const char *buf, size_t count)
 477 {
 478         struct ads7846 *ts = dev_get_drvdata(dev);
 479         unsigned long i;
 480
 481         if (strict_strtoul(buf, 10, &i))
 482                 return -EINVAL;
 483
 484         spin_lock_irq(&ts->lock);
 485
 486         if (i)
 487                 ads7846_disable(ts);
 488         else
 489                 ads7846_enable(ts);
 490
 491         spin_unlock_irq(&ts->lock);
 492
 493         return count;
 494 }
 495
 496 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 497
 498 static struct attribute *ads784x_attributes[] = {
 499         &dev_attr_pen_down.attr,
 500         &dev_attr_disable.attr,
 501         NULL,
 502 };
 503
 504 static struct attribute_group ads784x_attr_group = {
 505         .attrs = ads784x_attributes,
 506 };
 507
 508 /*--------------------------------------------------------------------------*/
 509
 510 static int get_pendown_state(struct ads7846 *ts)
 511 {
 512         if (ts->get_pendown_state)
 513                 return ts->get_pendown_state();
 514
 515         return !gpio_get_value(ts->gpio_pendown);
 516 }
 517
 518 static void null_wait_for_sync(void)
 519 {
 520 }
 521
 522 /*
 523  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 524  * to retrieve touchscreen status.
 525  *
 526  * The SPI transfer completion callback does the real work.  It reports
 527  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 528  */
 529
 530 static void ads7846_rx(void *ads)
 531 {
 532         struct ads7846          *ts = ads;
 533         struct ads7846_packet   *packet = ts->packet;
 534         unsigned                Rt;
 535         u16                     x, y, z1, z2;
 536
 537         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 538          * on-the-wire format as part of debouncing to get stable readings.
 539          */
 540         x = packet->tc.x;
 541         y = packet->tc.y;
 542         z1 = packet->tc.z1;
 543         z2 = packet->tc.z2;
 544
 545         /* range filtering */
 546         if (x == MAX_12BIT)
 547                 x = 0;
 548
 549         if (ts->model == 7843) {
 550                 Rt = ts->pressure_max / 2;
 551         } else if (likely(x && z1)) {
 552                 /* compute touch pressure resistance using equation #2 */
 553                 Rt = z2;
 554                 Rt -= z1;
 555                 Rt *= x;
 556                 Rt *= ts->x_plate_ohms;
 557                 Rt /= z1;
 558                 Rt = (Rt + 2047) >> 12;
 559         } else {
 560                 Rt = 0;
 561         }
 562
 563         /* Sample found inconsistent by debouncing or pressure is beyond
 564          * the maximum. Don't report it to user space, repeat at least
 565          * once more the measurement
 566          */
 567         if (packet->tc.ignore || Rt > ts->pressure_max) {
 568                 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
 569                          packet->tc.ignore, Rt);
 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                         dev_vdbg(&ts->spi->dev, "DOWN\n");
 599                 }
 600
 601                 if (ts->swap_xy)
 602                         swap(x, y);
 603
 604                 input_report_abs(input, ABS_X, x);
 605                 input_report_abs(input, ABS_Y, y);
 606                 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
 607
 608                 input_sync(input);
 609                 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 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                         dev_vdbg(&ts->spi->dev, "UP\n");
 720                 }
 721
 722                 /* measurement cycle ended */
 723                 if (!device_suspended(&ts->spi->dev)) {
 724                         ts->irq_disabled = 0;
 725                         enable_irq(ts->spi->irq);
 726                 }
 727                 ts->pending = 0;
 728         } else {
 729                 /* pen is still down, continue with the measurement */
 730                 ts->msg_idx = 0;
 731                 ts->wait_for_sync();
 732                 status = spi_async(ts->spi, &ts->msg[0]);
 733                 if (status)
 734                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 735         }
 736
 737         spin_unlock(&ts->lock);
 738         return HRTIMER_NORESTART;
 739 }
 740
 741 static irqreturn_t ads7846_irq(int irq, void *handle)
 742 {
 743         struct ads7846 *ts = handle;
 744         unsigned long flags;
 745
 746         spin_lock_irqsave(&ts->lock, flags);
 747         if (likely(get_pendown_state(ts))) {
 748                 if (!ts->irq_disabled) {
 749                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 750                          * like the other dispatchers:  it will report IRQs
 751                          * even after they've been disabled.  We work around
 752                          * that here.  (The "generic irq" framework may help...)
 753                          */
 754                         ts->irq_disabled = 1;
 755                         disable_irq_nosync(ts->spi->irq);
 756                         ts->pending = 1;
 757                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 758                                         HRTIMER_MODE_REL);
 759                 }
 760         }
 761         spin_unlock_irqrestore(&ts->lock, flags);
 762
 763         return IRQ_HANDLED;
 764 }
 765
 766 /*--------------------------------------------------------------------------*/
 767
 768 /* Must be called with ts->lock held */
 769 static void ads7846_disable(struct ads7846 *ts)
 770 {
 771         if (ts->disabled)
 772                 return;
 773
 774         ts->disabled = 1;
 775
 776         /* are we waiting for IRQ, or polling? */
 777         if (!ts->pending) {
 778                 ts->irq_disabled = 1;
 779                 disable_irq(ts->spi->irq);
 780         } else {
 781                 /* the timer will run at least once more, and
 782                  * leave everything in a clean state, IRQ disabled
 783                  */
 784                 while (ts->pending) {
 785                         spin_unlock_irq(&ts->lock);
 786                         msleep(1);
 787                         spin_lock_irq(&ts->lock);
 788                 }
 789         }
 790
 791         /* we know the chip's in lowpower mode since we always
 792          * leave it that way after every request
 793          */
 794 }
 795
 796 /* Must be called with ts->lock held */
 797 static void ads7846_enable(struct ads7846 *ts)
 798 {
 799         if (!ts->disabled)
 800                 return;
 801
 802         ts->disabled = 0;
 803         ts->irq_disabled = 0;
 804         enable_irq(ts->spi->irq);
 805 }
 806
 807 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 808 {
 809         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 810
 811         spin_lock_irq(&ts->lock);
 812
 813         ts->is_suspended = 1;
 814         ads7846_disable(ts);
 815
 816         spin_unlock_irq(&ts->lock);
 817
 818         return 0;
 819
 820 }
 821
 822 static int ads7846_resume(struct spi_device *spi)
 823 {
 824         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 825
 826         spin_lock_irq(&ts->lock);
 827
 828         ts->is_suspended = 0;
 829         ads7846_enable(ts);
 830
 831         spin_unlock_irq(&ts->lock);
 832
 833         return 0;
 834 }
 835
 836 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 837 {
 838         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 839         int err;
 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 && !gpio_is_valid(pdata->gpio_pendown)) {
 846                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 847                 return -EINVAL;
 848         }
 849
 850         if (pdata->get_pendown_state) {
 851                 ts->get_pendown_state = pdata->get_pendown_state;
 852                 return 0;
 853         }
 854
 855         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 856         if (err) {
 857                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 858                                 pdata->gpio_pendown);
 859                 return err;
 860         }
 861
 862         ts->gpio_pendown = pdata->gpio_pendown;
 863         return 0;
 864 }
 865
 866 static int __devinit ads7846_probe(struct spi_device *spi)
 867 {
 868         struct ads7846                  *ts;
 869         struct ads7846_packet           *packet;
 870         struct input_dev                *input_dev;
 871         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 872         struct spi_message              *m;
 873         struct spi_transfer             *x;
 874         int                             vref;
 875         int                             err;
 876
 877         if (!spi->irq) {
 878                 dev_dbg(&spi->dev, "no IRQ?\n");
 879                 return -ENODEV;
 880         }
 881
 882         if (!pdata) {
 883                 dev_dbg(&spi->dev, "no platform data?\n");
 884                 return -ENODEV;
 885         }
 886
 887         /* don't exceed max specified sample rate */
 888         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 889                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 890                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 891                 return -EINVAL;
 892         }
 893
 894         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 895          * that even if the hardware can do that, the SPI controller driver
 896          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 897          */
 898         spi->bits_per_word = 8;
 899         spi->mode = SPI_MODE_0;
 900         err = spi_setup(spi);
 901         if (err < 0)
 902                 return err;
 903
 904         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 905         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
 906         input_dev = input_allocate_device();
 907         if (!ts || !packet || !input_dev) {
 908                 err = -ENOMEM;
 909                 goto err_free_mem;
 910         }
 911
 912         dev_set_drvdata(&spi->dev, ts);
 913
 914         ts->packet = packet;
 915         ts->spi = spi;
 916         ts->input = input_dev;
 917         ts->vref_mv = pdata->vref_mv;
 918         ts->swap_xy = pdata->swap_xy;
 919
 920         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 921         ts->timer.function = ads7846_timer;
 922
 923         spin_lock_init(&ts->lock);
 924
 925         ts->model = pdata->model ? : 7846;
 926         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 927         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 928         ts->pressure_max = pdata->pressure_max ? : ~0;
 929
 930         if (pdata->filter != NULL) {
 931                 if (pdata->filter_init != NULL) {
 932                         err = pdata->filter_init(pdata, &ts->filter_data);
 933                         if (err < 0)
 934                                 goto err_free_mem;
 935                 }
 936                 ts->filter = pdata->filter;
 937                 ts->filter_cleanup = pdata->filter_cleanup;
 938         } else if (pdata->debounce_max) {
 939                 ts->debounce_max = pdata->debounce_max;
 940                 if (ts->debounce_max < 2)
 941                         ts->debounce_max = 2;
 942                 ts->debounce_tol = pdata->debounce_tol;
 943                 ts->debounce_rep = pdata->debounce_rep;
 944                 ts->filter = ads7846_debounce;
 945                 ts->filter_data = ts;
 946         } else
 947                 ts->filter = ads7846_no_filter;
 948
 949         err = setup_pendown(spi, ts);
 950         if (err)
 951                 goto err_cleanup_filter;
 952
 953         if (pdata->penirq_recheck_delay_usecs)
 954                 ts->penirq_recheck_delay_usecs =
 955                                 pdata->penirq_recheck_delay_usecs;
 956
 957         ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
 958
 959         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
 960         snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
 961
 962         input_dev->name = ts->name;
 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_info(&spi->dev,
1145                         "trying pin change workaround on irq %d\n", spi->irq);
1146                 err = request_irq(spi->irq, ads7846_irq,
1147                                   IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
1148                                   spi->dev.driver->name, ts);
1149                 if (err) {
1150                         dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1151                         goto err_free_gpio;
1152                 }
1153         }
1154
1155         err = ads784x_hwmon_register(spi, ts);
1156         if (err)
1157                 goto err_free_irq;
1158
1159         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1160
1161         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1162          * the touchscreen, in case it's not connected.
1163          */
1164         (void) ads7846_read12_ser(&spi->dev,
1165                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1166
1167         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1168         if (err)
1169                 goto err_remove_hwmon;
1170
1171         err = input_register_device(input_dev);
1172         if (err)
1173                 goto err_remove_attr_group;
1174
1175         return 0;
1176
1177  err_remove_attr_group:
1178         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1179  err_remove_hwmon:
1180         ads784x_hwmon_unregister(spi, ts);
1181  err_free_irq:
1182         free_irq(spi->irq, ts);
1183  err_free_gpio:
1184         if (ts->gpio_pendown != -1)
1185                 gpio_free(ts->gpio_pendown);
1186  err_cleanup_filter:
1187         if (ts->filter_cleanup)
1188                 ts->filter_cleanup(ts->filter_data);
1189  err_free_mem:
1190         input_free_device(input_dev);
1191         kfree(packet);
1192         kfree(ts);
1193         return err;
1194 }
1195
1196 static int __devexit ads7846_remove(struct spi_device *spi)
1197 {
1198         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1199
1200         ads784x_hwmon_unregister(spi, ts);
1201         input_unregister_device(ts->input);
1202
1203         ads7846_suspend(spi, PMSG_SUSPEND);
1204
1205         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1206
1207         free_irq(ts->spi->irq, ts);
1208         /* suspend left the IRQ disabled */
1209         enable_irq(ts->spi->irq);
1210
1211         if (ts->gpio_pendown != -1)
1212                 gpio_free(ts->gpio_pendown);
1213
1214         if (ts->filter_cleanup)
1215                 ts->filter_cleanup(ts->filter_data);
1216
1217         kfree(ts->packet);
1218         kfree(ts);
1219
1220         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1221         return 0;
1222 }
1223
1224 static struct spi_driver ads7846_driver = {
1225         .driver = {
1226                 .name   = "ads7846",
1227                 .bus    = &spi_bus_type,
1228                 .owner  = THIS_MODULE,
1229         },
1230         .probe          = ads7846_probe,
1231         .remove         = __devexit_p(ads7846_remove),
1232         .suspend        = ads7846_suspend,
1233         .resume         = ads7846_resume,
1234 };
1235
1236 static int __init ads7846_init(void)
1237 {
1238         return spi_register_driver(&ads7846_driver);
1239 }
1240 module_init(ads7846_init);
1241
1242 static void __exit ads7846_exit(void)
1243 {
1244         spi_unregister_driver(&ads7846_driver);
1245 }
1246 module_exit(ads7846_exit);
1247
1248 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1249 MODULE_LICENSE("GPL");
1250 MODULE_ALIAS("spi:ads7846");