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 struct ads7846 {
  73         struct input_dev        *input;
  74         char                    phys[32];
  75
  76         struct spi_device       *spi;
  77
  78 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  79         struct attribute_group  *attr_group;
  80         struct device           *hwmon;
  81 #endif
  82
  83         u16                     model;
  84         u16                     vref_mv;
  85         u16                     vref_delay_usecs;
  86         u16                     x_plate_ohms;
  87         u16                     pressure_max;
  88
  89         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  90         u16                     dummy;          /* for the pwrdown read */
  91         struct ts_event         tc;
  92
  93         struct spi_transfer     xfer[18];
  94         struct spi_message      msg[5];
  95         struct spi_message      *last_msg;
  96         int                     msg_idx;
  97         int                     read_cnt;
  98         int                     read_rep;
  99         int                     last_read;
 100
 101         u16                     debounce_max;
 102         u16                     debounce_tol;
 103         u16                     debounce_rep;
 104
 105         u16                     penirq_recheck_delay_usecs;
 106
 107         spinlock_t              lock;
 108         struct hrtimer          timer;
 109         unsigned                pendown:1;      /* P: lock */
 110         unsigned                pending:1;      /* P: lock */
 111 // FIXME remove "irq_disabled"
 112         unsigned                irq_disabled:1; /* P: lock */
 113         unsigned                disabled:1;
 114         unsigned                is_suspended:1;
 115
 116         int                     (*filter)(void *data, int data_idx, int *val);
 117         void                    *filter_data;
 118         void                    (*filter_cleanup)(void *data);
 119         int                     (*get_pendown_state)(void);
 120         int                     gpio_pendown;
 121 };
 122
 123 /* leave chip selected when we're done, for quicker re-select? */
 124 #if     0
 125 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 126 #else
 127 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 128 #endif
 129
 130 /*--------------------------------------------------------------------------*/
 131
 132 /* The ADS7846 has touchscreen and other sensors.
 133  * Earlier ads784x chips are somewhat compatible.
 134  */
 135 #define ADS_START               (1 << 7)
 136 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 137 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 138 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 139 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 140 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 141 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 142 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 143 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 144 #define ADS_8_BIT               (1 << 3)
 145 #define ADS_12_BIT              (0 << 3)
 146 #define ADS_SER                 (1 << 2)        /* non-differential */
 147 #define ADS_DFR                 (0 << 2)        /* differential */
 148 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 149 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 150 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 151 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 152
 153 #define MAX_12BIT       ((1<<12)-1)
 154
 155 /* leave ADC powered up (disables penirq) between differential samples */
 156 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 157         | ADS_12_BIT | ADS_DFR | \
 158         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 159
 160 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 161 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 162 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 163
 164 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 165 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 166
 167 /* single-ended samples need to first power up reference voltage;
 168  * we leave both ADC and VREF powered
 169  */
 170 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 171         | ADS_12_BIT | ADS_SER)
 172
 173 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 174 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 175
 176 /*--------------------------------------------------------------------------*/
 177
 178 /*
 179  * Non-touchscreen sensors only use single-ended conversions.
 180  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 181  * ads7846 lets that pin be unconnected, to use internal vREF.
 182  */
 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                     use_internal;
 210
 211         if (!req)
 212                 return -ENOMEM;
 213
 214         spi_message_init(&req->msg);
 215
 216         /* FIXME boards with ads7846 might use external vref instead ... */
 217         use_internal = (ts->model == 7846);
 218
 219         /* maybe turn on internal vREF, and let it settle */
 220         if (use_internal) {
 221                 req->ref_on = REF_ON;
 222                 req->xfer[0].tx_buf = &req->ref_on;
 223                 req->xfer[0].len = 1;
 224                 spi_message_add_tail(&req->xfer[0], &req->msg);
 225
 226                 req->xfer[1].rx_buf = &req->scratch;
 227                 req->xfer[1].len = 2;
 228
 229                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 230                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 231                 spi_message_add_tail(&req->xfer[1], &req->msg);
 232         }
 233
 234         /* take sample */
 235         req->command = (u8) command;
 236         req->xfer[2].tx_buf = &req->command;
 237         req->xfer[2].len = 1;
 238         spi_message_add_tail(&req->xfer[2], &req->msg);
 239
 240         req->xfer[3].rx_buf = &req->sample;
 241         req->xfer[3].len = 2;
 242         spi_message_add_tail(&req->xfer[3], &req->msg);
 243
 244         /* REVISIT:  take a few more samples, and compare ... */
 245
 246         /* converter in low power mode & enable PENIRQ */
 247         req->ref_off = PWRDOWN;
 248         req->xfer[4].tx_buf = &req->ref_off;
 249         req->xfer[4].len = 1;
 250         spi_message_add_tail(&req->xfer[4], &req->msg);
 251
 252         req->xfer[5].rx_buf = &req->scratch;
 253         req->xfer[5].len = 2;
 254         CS_CHANGE(req->xfer[5]);
 255         spi_message_add_tail(&req->xfer[5], &req->msg);
 256
 257         ts->irq_disabled = 1;
 258         disable_irq(spi->irq);
 259         status = spi_sync(spi, &req->msg);
 260         ts->irq_disabled = 0;
 261         enable_irq(spi->irq);
 262
 263         if (status == 0) {
 264                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 265                 status = be16_to_cpu(req->sample);
 266                 status = status >> 3;
 267                 status &= 0x0fff;
 268         }
 269
 270         kfree(req);
 271         return status;
 272 }
 273
 274 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 275
 276 #define SHOW(name, var, adjust) static ssize_t \
 277 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 278 { \
 279         struct ads7846 *ts = dev_get_drvdata(dev); \
 280         ssize_t v = ads7846_read12_ser(dev, \
 281                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 282         if (v < 0) \
 283                 return v; \
 284         return sprintf(buf, "%u\n", adjust(ts, v)); \
 285 } \
 286 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 287
 288
 289 /* Sysfs conventions report temperatures in millidegrees Celcius.
 290  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 291  * accuracy scheme without calibration data.  For now we won't try either;
 292  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 293  */
 294 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 295 {
 296         return v;
 297 }
 298
 299 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 300 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 301
 302
 303 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 304  * if we know vREF.  userspace may need to scale vAUX to match the board's
 305  * external resistors; we assume that vBATT only uses the internal ones.
 306  */
 307 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 308 {
 309         unsigned retval = v;
 310
 311         /* external resistors may scale vAUX into 0..vREF */
 312         retval *= ts->vref_mv;
 313         retval = retval >> 12;
 314         return retval;
 315 }
 316
 317 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 318 {
 319         unsigned retval = vaux_adjust(ts, v);
 320
 321         /* ads7846 has a resistor ladder to scale this signal down */
 322         if (ts->model == 7846)
 323                 retval *= 4;
 324         return retval;
 325 }
 326
 327 SHOW(in0_input, vaux, vaux_adjust)
 328 SHOW(in1_input, vbatt, vbatt_adjust)
 329
 330
 331 static struct attribute *ads7846_attributes[] = {
 332         &dev_attr_temp0.attr,
 333         &dev_attr_temp1.attr,
 334         &dev_attr_in0_input.attr,
 335         &dev_attr_in1_input.attr,
 336         NULL,
 337 };
 338
 339 static struct attribute_group ads7846_attr_group = {
 340         .attrs = ads7846_attributes,
 341 };
 342
 343 static struct attribute *ads7843_attributes[] = {
 344         &dev_attr_in0_input.attr,
 345         &dev_attr_in1_input.attr,
 346         NULL,
 347 };
 348
 349 static struct attribute_group ads7843_attr_group = {
 350         .attrs = ads7843_attributes,
 351 };
 352
 353 static struct attribute *ads7845_attributes[] = {
 354         &dev_attr_in0_input.attr,
 355         NULL,
 356 };
 357
 358 static struct attribute_group ads7845_attr_group = {
 359         .attrs = ads7845_attributes,
 360 };
 361
 362 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 363 {
 364         struct device *hwmon;
 365         int err;
 366
 367         /* hwmon sensors need a reference voltage */
 368         switch (ts->model) {
 369         case 7846:
 370                 if (!ts->vref_mv) {
 371                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 372                         ts->vref_mv = 2500;
 373                 }
 374                 break;
 375         case 7845:
 376         case 7843:
 377                 if (!ts->vref_mv) {
 378                         dev_warn(&spi->dev,
 379                                 "external vREF for ADS%d not specified\n",
 380                                 ts->model);
 381                         return 0;
 382                 }
 383                 break;
 384         }
 385
 386         /* different chips have different sensor groups */
 387         switch (ts->model) {
 388         case 7846:
 389                 ts->attr_group = &ads7846_attr_group;
 390                 break;
 391         case 7845:
 392                 ts->attr_group = &ads7845_attr_group;
 393                 break;
 394         case 7843:
 395                 ts->attr_group = &ads7843_attr_group;
 396                 break;
 397         default:
 398                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 399                 return 0;
 400         }
 401
 402         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 403         if (err)
 404                 return err;
 405
 406         hwmon = hwmon_device_register(&spi->dev);
 407         if (IS_ERR(hwmon)) {
 408                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 409                 return PTR_ERR(hwmon);
 410         }
 411
 412         ts->hwmon = hwmon;
 413         return 0;
 414 }
 415
 416 static void ads784x_hwmon_unregister(struct spi_device *spi,
 417                                      struct ads7846 *ts)
 418 {
 419         if (ts->hwmon) {
 420                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 421                 hwmon_device_unregister(ts->hwmon);
 422         }
 423 }
 424
 425 #else
 426 static inline int ads784x_hwmon_register(struct spi_device *spi,
 427                                          struct ads7846 *ts)
 428 {
 429         return 0;
 430 }
 431
 432 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 433                                             struct ads7846 *ts)
 434 {
 435 }
 436 #endif
 437
 438 static int is_pen_down(struct device *dev)
 439 {
 440         struct ads7846  *ts = dev_get_drvdata(dev);
 441
 442         return ts->pendown;
 443 }
 444
 445 static ssize_t ads7846_pen_down_show(struct device *dev,
 446                                      struct device_attribute *attr, char *buf)
 447 {
 448         return sprintf(buf, "%u\n", is_pen_down(dev));
 449 }
 450
 451 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 452
 453 static ssize_t ads7846_disable_show(struct device *dev,
 454                                      struct device_attribute *attr, char *buf)
 455 {
 456         struct ads7846  *ts = dev_get_drvdata(dev);
 457
 458         return sprintf(buf, "%u\n", ts->disabled);
 459 }
 460
 461 static ssize_t ads7846_disable_store(struct device *dev,
 462                                      struct device_attribute *attr,
 463                                      const char *buf, size_t count)
 464 {
 465         struct ads7846 *ts = dev_get_drvdata(dev);
 466         char *endp;
 467         int i;
 468
 469         i = simple_strtoul(buf, &endp, 10);
 470         spin_lock_irq(&ts->lock);
 471
 472         if (i)
 473                 ads7846_disable(ts);
 474         else
 475                 ads7846_enable(ts);
 476
 477         spin_unlock_irq(&ts->lock);
 478
 479         return count;
 480 }
 481
 482 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 483
 484 static struct attribute *ads784x_attributes[] = {
 485         &dev_attr_pen_down.attr,
 486         &dev_attr_disable.attr,
 487         NULL,
 488 };
 489
 490 static struct attribute_group ads784x_attr_group = {
 491         .attrs = ads784x_attributes,
 492 };
 493
 494 /*--------------------------------------------------------------------------*/
 495
 496 static int get_pendown_state(struct ads7846 *ts)
 497 {
 498         if (ts->get_pendown_state)
 499                 return ts->get_pendown_state();
 500
 501         return !gpio_get_value(ts->gpio_pendown);
 502 }
 503
 504 /*
 505  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 506  * to retrieve touchscreen status.
 507  *
 508  * The SPI transfer completion callback does the real work.  It reports
 509  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 510  */
 511
 512 static void ads7846_rx(void *ads)
 513 {
 514         struct ads7846          *ts = ads;
 515         unsigned                Rt;
 516         u16                     x, y, z1, z2;
 517
 518         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 519          * on-the-wire format as part of debouncing to get stable readings.
 520          */
 521         x = ts->tc.x;
 522         y = ts->tc.y;
 523         z1 = ts->tc.z1;
 524         z2 = ts->tc.z2;
 525
 526         /* range filtering */
 527         if (x == MAX_12BIT)
 528                 x = 0;
 529
 530         if (ts->model == 7843) {
 531                 Rt = ts->pressure_max / 2;
 532         } else if (likely(x && z1)) {
 533                 /* compute touch pressure resistance using equation #2 */
 534                 Rt = z2;
 535                 Rt -= z1;
 536                 Rt *= x;
 537                 Rt *= ts->x_plate_ohms;
 538                 Rt /= z1;
 539                 Rt = (Rt + 2047) >> 12;
 540         } else {
 541                 Rt = 0;
 542         }
 543
 544         /* Sample found inconsistent by debouncing or pressure is beyond
 545          * the maximum. Don't report it to user space, repeat at least
 546          * once more the measurement
 547          */
 548         if (ts->tc.ignore || Rt > ts->pressure_max) {
 549 #ifdef VERBOSE
 550                 pr_debug("%s: ignored %d pressure %d\n",
 551                         ts->spi->dev.bus_id, ts->tc.ignore, Rt);
 552 #endif
 553                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 554                               HRTIMER_MODE_REL);
 555                 return;
 556         }
 557
 558         /* Maybe check the pendown state before reporting. This discards
 559          * false readings when the pen is lifted.
 560          */
 561         if (ts->penirq_recheck_delay_usecs) {
 562                 udelay(ts->penirq_recheck_delay_usecs);
 563                 if (!get_pendown_state(ts))
 564                         Rt = 0;
 565         }
 566
 567         /* NOTE: We can't rely on the pressure to determine the pen down
 568          * state, even this controller has a pressure sensor.  The pressure
 569          * value can fluctuate for quite a while after lifting the pen and
 570          * in some cases may not even settle at the expected value.
 571          *
 572          * The only safe way to check for the pen up condition is in the
 573          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 574          */
 575         if (Rt) {
 576                 struct input_dev *input = ts->input;
 577
 578                 if (!ts->pendown) {
 579                         input_report_key(input, BTN_TOUCH, 1);
 580                         ts->pendown = 1;
 581 #ifdef VERBOSE
 582                         dev_dbg(&ts->spi->dev, "DOWN\n");
 583 #endif
 584                 }
 585                 input_report_abs(input, ABS_X, x);
 586                 input_report_abs(input, ABS_Y, y);
 587                 input_report_abs(input, ABS_PRESSURE, Rt);
 588
 589                 input_sync(input);
 590 #ifdef VERBOSE
 591                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 592 #endif
 593         }
 594
 595         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 596                         HRTIMER_MODE_REL);
 597 }
 598
 599 static int ads7846_debounce(void *ads, int data_idx, int *val)
 600 {
 601         struct ads7846          *ts = ads;
 602
 603         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 604                 /* Start over collecting consistent readings. */
 605                 ts->read_rep = 0;
 606                 /* Repeat it, if this was the first read or the read
 607                  * wasn't consistent enough. */
 608                 if (ts->read_cnt < ts->debounce_max) {
 609                         ts->last_read = *val;
 610                         ts->read_cnt++;
 611                         return ADS7846_FILTER_REPEAT;
 612                 } else {
 613                         /* Maximum number of debouncing reached and still
 614                          * not enough number of consistent readings. Abort
 615                          * the whole sample, repeat it in the next sampling
 616                          * period.
 617                          */
 618                         ts->read_cnt = 0;
 619                         return ADS7846_FILTER_IGNORE;
 620                 }
 621         } else {
 622                 if (++ts->read_rep > ts->debounce_rep) {
 623                         /* Got a good reading for this coordinate,
 624                          * go for the next one. */
 625                         ts->read_cnt = 0;
 626                         ts->read_rep = 0;
 627                         return ADS7846_FILTER_OK;
 628                 } else {
 629                         /* Read more values that are consistent. */
 630                         ts->read_cnt++;
 631                         return ADS7846_FILTER_REPEAT;
 632                 }
 633         }
 634 }
 635
 636 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 637 {
 638         return ADS7846_FILTER_OK;
 639 }
 640
 641 static void ads7846_rx_val(void *ads)
 642 {
 643         struct ads7846 *ts = ads;
 644         struct spi_message *m;
 645         struct spi_transfer *t;
 646         int val;
 647         int action;
 648         int status;
 649
 650         m = &ts->msg[ts->msg_idx];
 651         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 652
 653         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 654          * built from two 8 bit values written msb-first.
 655          */
 656         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 657
 658         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 659         switch (action) {
 660         case ADS7846_FILTER_REPEAT:
 661                 break;
 662         case ADS7846_FILTER_IGNORE:
 663                 ts->tc.ignore = 1;
 664                 /* Last message will contain ads7846_rx() as the
 665                  * completion function.
 666                  */
 667                 m = ts->last_msg;
 668                 break;
 669         case ADS7846_FILTER_OK:
 670                 *(u16 *)t->rx_buf = val;
 671                 ts->tc.ignore = 0;
 672                 m = &ts->msg[++ts->msg_idx];
 673                 break;
 674         default:
 675                 BUG();
 676         }
 677         status = spi_async(ts->spi, m);
 678         if (status)
 679                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 680                                 status);
 681 }
 682
 683 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 684 {
 685         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 686         int             status = 0;
 687
 688         spin_lock_irq(&ts->lock);
 689
 690         if (unlikely(!get_pendown_state(ts) ||
 691                      device_suspended(&ts->spi->dev))) {
 692                 if (ts->pendown) {
 693                         struct input_dev *input = ts->input;
 694
 695                         input_report_key(input, BTN_TOUCH, 0);
 696                         input_report_abs(input, ABS_PRESSURE, 0);
 697                         input_sync(input);
 698
 699                         ts->pendown = 0;
 700 #ifdef VERBOSE
 701                         dev_dbg(&ts->spi->dev, "UP\n");
 702 #endif
 703                 }
 704
 705                 /* measurement cycle ended */
 706                 if (!device_suspended(&ts->spi->dev)) {
 707                         ts->irq_disabled = 0;
 708                         enable_irq(ts->spi->irq);
 709                 }
 710                 ts->pending = 0;
 711         } else {
 712                 /* pen is still down, continue with the measurement */
 713                 ts->msg_idx = 0;
 714                 status = spi_async(ts->spi, &ts->msg[0]);
 715                 if (status)
 716                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 717         }
 718
 719         spin_unlock_irq(&ts->lock);
 720         return HRTIMER_NORESTART;
 721 }
 722
 723 static irqreturn_t ads7846_irq(int irq, void *handle)
 724 {
 725         struct ads7846 *ts = handle;
 726         unsigned long flags;
 727
 728         spin_lock_irqsave(&ts->lock, flags);
 729         if (likely(get_pendown_state(ts))) {
 730                 if (!ts->irq_disabled) {
 731                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 732                          * like the other dispatchers:  it will report IRQs
 733                          * even after they've been disabled.  We work around
 734                          * that here.  (The "generic irq" framework may help...)
 735                          */
 736                         ts->irq_disabled = 1;
 737                         disable_irq(ts->spi->irq);
 738                         ts->pending = 1;
 739                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 740                                         HRTIMER_MODE_REL);
 741                 }
 742         }
 743         spin_unlock_irqrestore(&ts->lock, flags);
 744
 745         return IRQ_HANDLED;
 746 }
 747
 748 /*--------------------------------------------------------------------------*/
 749
 750 /* Must be called with ts->lock held */
 751 static void ads7846_disable(struct ads7846 *ts)
 752 {
 753         if (ts->disabled)
 754                 return;
 755
 756         ts->disabled = 1;
 757
 758         /* are we waiting for IRQ, or polling? */
 759         if (!ts->pending) {
 760                 ts->irq_disabled = 1;
 761                 disable_irq(ts->spi->irq);
 762         } else {
 763                 /* the timer will run at least once more, and
 764                  * leave everything in a clean state, IRQ disabled
 765                  */
 766                 while (ts->pending) {
 767                         spin_unlock_irq(&ts->lock);
 768                         msleep(1);
 769                         spin_lock_irq(&ts->lock);
 770                 }
 771         }
 772
 773         /* we know the chip's in lowpower mode since we always
 774          * leave it that way after every request
 775          */
 776
 777 }
 778
 779 /* Must be called with ts->lock held */
 780 static void ads7846_enable(struct ads7846 *ts)
 781 {
 782         if (!ts->disabled)
 783                 return;
 784
 785         ts->disabled = 0;
 786         ts->irq_disabled = 0;
 787         enable_irq(ts->spi->irq);
 788 }
 789
 790 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 791 {
 792         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 793
 794         spin_lock_irq(&ts->lock);
 795
 796         ts->is_suspended = 1;
 797         ads7846_disable(ts);
 798
 799         spin_unlock_irq(&ts->lock);
 800
 801         return 0;
 802
 803 }
 804
 805 static int ads7846_resume(struct spi_device *spi)
 806 {
 807         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 808
 809         spin_lock_irq(&ts->lock);
 810
 811         ts->is_suspended = 0;
 812         ads7846_enable(ts);
 813
 814         spin_unlock_irq(&ts->lock);
 815
 816         return 0;
 817 }
 818
 819 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 820 {
 821         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 822         int err;
 823
 824         /* REVISIT when the irq can be triggered active-low, or if for some
 825          * reason the touchscreen isn't hooked up, we don't need to access
 826          * the pendown state.
 827          */
 828         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
 829                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 830                 return -EINVAL;
 831         }
 832
 833         if (pdata->get_pendown_state) {
 834                 ts->get_pendown_state = pdata->get_pendown_state;
 835                 return 0;
 836         }
 837
 838         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 839         if (err) {
 840                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 841                                 pdata->gpio_pendown);
 842                 return err;
 843         }
 844
 845         ts->gpio_pendown = pdata->gpio_pendown;
 846         return 0;
 847 }
 848
 849 static int __devinit ads7846_probe(struct spi_device *spi)
 850 {
 851         struct ads7846                  *ts;
 852         struct input_dev                *input_dev;
 853         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 854         struct spi_message              *m;
 855         struct spi_transfer             *x;
 856         int                             vref;
 857         int                             err;
 858
 859         if (!spi->irq) {
 860                 dev_dbg(&spi->dev, "no IRQ?\n");
 861                 return -ENODEV;
 862         }
 863
 864         if (!pdata) {
 865                 dev_dbg(&spi->dev, "no platform data?\n");
 866                 return -ENODEV;
 867         }
 868
 869         /* don't exceed max specified sample rate */
 870         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 871                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 872                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 873                 return -EINVAL;
 874         }
 875
 876         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 877          * that even if the hardware can do that, the SPI controller driver
 878          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 879          */
 880         spi->bits_per_word = 8;
 881         spi->mode = SPI_MODE_0;
 882         err = spi_setup(spi);
 883         if (err < 0)
 884                 return err;
 885
 886         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 887         input_dev = input_allocate_device();
 888         if (!ts || !input_dev) {
 889                 err = -ENOMEM;
 890                 goto err_free_mem;
 891         }
 892
 893         dev_set_drvdata(&spi->dev, ts);
 894
 895         ts->spi = spi;
 896         ts->input = input_dev;
 897         ts->vref_mv = pdata->vref_mv;
 898
 899         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 900         ts->timer.function = ads7846_timer;
 901
 902         spin_lock_init(&ts->lock);
 903
 904         ts->model = pdata->model ? : 7846;
 905         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 906         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 907         ts->pressure_max = pdata->pressure_max ? : ~0;
 908
 909         if (pdata->filter != NULL) {
 910                 if (pdata->filter_init != NULL) {
 911                         err = pdata->filter_init(pdata, &ts->filter_data);
 912                         if (err < 0)
 913                                 goto err_free_mem;
 914                 }
 915                 ts->filter = pdata->filter;
 916                 ts->filter_cleanup = pdata->filter_cleanup;
 917         } else if (pdata->debounce_max) {
 918                 ts->debounce_max = pdata->debounce_max;
 919                 if (ts->debounce_max < 2)
 920                         ts->debounce_max = 2;
 921                 ts->debounce_tol = pdata->debounce_tol;
 922                 ts->debounce_rep = pdata->debounce_rep;
 923                 ts->filter = ads7846_debounce;
 924                 ts->filter_data = ts;
 925         } else
 926                 ts->filter = ads7846_no_filter;
 927
 928         err = setup_pendown(spi, ts);
 929         if (err)
 930                 goto err_cleanup_filter;
 931
 932         if (pdata->penirq_recheck_delay_usecs)
 933                 ts->penirq_recheck_delay_usecs =
 934                                 pdata->penirq_recheck_delay_usecs;
 935
 936         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 937
 938         input_dev->name = "ADS784x Touchscreen";
 939         input_dev->phys = ts->phys;
 940         input_dev->dev.parent = &spi->dev;
 941
 942         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 943         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 944         input_set_abs_params(input_dev, ABS_X,
 945                         pdata->x_min ? : 0,
 946                         pdata->x_max ? : MAX_12BIT,
 947                         0, 0);
 948         input_set_abs_params(input_dev, ABS_Y,
 949                         pdata->y_min ? : 0,
 950                         pdata->y_max ? : MAX_12BIT,
 951                         0, 0);
 952         input_set_abs_params(input_dev, ABS_PRESSURE,
 953                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 954
 955         vref = pdata->keep_vref_on;
 956
 957         /* set up the transfers to read touchscreen state; this assumes we
 958          * use formula #2 for pressure, not #3.
 959          */
 960         m = &ts->msg[0];
 961         x = ts->xfer;
 962
 963         spi_message_init(m);
 964
 965         /* y- still on; turn on only y+ (and ADC) */
 966         ts->read_y = READ_Y(vref);
 967         x->tx_buf = &ts->read_y;
 968         x->len = 1;
 969         spi_message_add_tail(x, m);
 970
 971         x++;
 972         x->rx_buf = &ts->tc.y;
 973         x->len = 2;
 974         spi_message_add_tail(x, m);
 975
 976         /* the first sample after switching drivers can be low quality;
 977          * optionally discard it, using a second one after the signals
 978          * have had enough time to stabilize.
 979          */
 980         if (pdata->settle_delay_usecs) {
 981                 x->delay_usecs = pdata->settle_delay_usecs;
 982
 983                 x++;
 984                 x->tx_buf = &ts->read_y;
 985                 x->len = 1;
 986                 spi_message_add_tail(x, m);
 987
 988                 x++;
 989                 x->rx_buf = &ts->tc.y;
 990                 x->len = 2;
 991                 spi_message_add_tail(x, m);
 992         }
 993
 994         m->complete = ads7846_rx_val;
 995         m->context = ts;
 996
 997         m++;
 998         spi_message_init(m);
 999
1000         /* turn y- off, x+ on, then leave in lowpower */
1001         x++;
1002         ts->read_x = READ_X(vref);
1003         x->tx_buf = &ts->read_x;
1004         x->len = 1;
1005         spi_message_add_tail(x, m);
1006
1007         x++;
1008         x->rx_buf = &ts->tc.x;
1009         x->len = 2;
1010         spi_message_add_tail(x, m);
1011
1012         /* ... maybe discard first sample ... */
1013         if (pdata->settle_delay_usecs) {
1014                 x->delay_usecs = pdata->settle_delay_usecs;
1015
1016                 x++;
1017                 x->tx_buf = &ts->read_x;
1018                 x->len = 1;
1019                 spi_message_add_tail(x, m);
1020
1021                 x++;
1022                 x->rx_buf = &ts->tc.x;
1023                 x->len = 2;
1024                 spi_message_add_tail(x, m);
1025         }
1026
1027         m->complete = ads7846_rx_val;
1028         m->context = ts;
1029
1030         /* turn y+ off, x- on; we'll use formula #2 */
1031         if (ts->model == 7846) {
1032                 m++;
1033                 spi_message_init(m);
1034
1035                 x++;
1036                 ts->read_z1 = READ_Z1(vref);
1037                 x->tx_buf = &ts->read_z1;
1038                 x->len = 1;
1039                 spi_message_add_tail(x, m);
1040
1041                 x++;
1042                 x->rx_buf = &ts->tc.z1;
1043                 x->len = 2;
1044                 spi_message_add_tail(x, m);
1045
1046                 /* ... maybe discard first sample ... */
1047                 if (pdata->settle_delay_usecs) {
1048                         x->delay_usecs = pdata->settle_delay_usecs;
1049
1050                         x++;
1051                         x->tx_buf = &ts->read_z1;
1052                         x->len = 1;
1053                         spi_message_add_tail(x, m);
1054
1055                         x++;
1056                         x->rx_buf = &ts->tc.z1;
1057                         x->len = 2;
1058                         spi_message_add_tail(x, m);
1059                 }
1060
1061                 m->complete = ads7846_rx_val;
1062                 m->context = ts;
1063
1064                 m++;
1065                 spi_message_init(m);
1066
1067                 x++;
1068                 ts->read_z2 = READ_Z2(vref);
1069                 x->tx_buf = &ts->read_z2;
1070                 x->len = 1;
1071                 spi_message_add_tail(x, m);
1072
1073                 x++;
1074                 x->rx_buf = &ts->tc.z2;
1075                 x->len = 2;
1076                 spi_message_add_tail(x, m);
1077
1078                 /* ... maybe discard first sample ... */
1079                 if (pdata->settle_delay_usecs) {
1080                         x->delay_usecs = pdata->settle_delay_usecs;
1081
1082                         x++;
1083                         x->tx_buf = &ts->read_z2;
1084                         x->len = 1;
1085                         spi_message_add_tail(x, m);
1086
1087                         x++;
1088                         x->rx_buf = &ts->tc.z2;
1089                         x->len = 2;
1090                         spi_message_add_tail(x, m);
1091                 }
1092
1093                 m->complete = ads7846_rx_val;
1094                 m->context = ts;
1095         }
1096
1097         /* power down */
1098         m++;
1099         spi_message_init(m);
1100
1101         x++;
1102         ts->pwrdown = PWRDOWN;
1103         x->tx_buf = &ts->pwrdown;
1104         x->len = 1;
1105         spi_message_add_tail(x, m);
1106
1107         x++;
1108         x->rx_buf = &ts->dummy;
1109         x->len = 2;
1110         CS_CHANGE(*x);
1111         spi_message_add_tail(x, m);
1112
1113         m->complete = ads7846_rx;
1114         m->context = ts;
1115
1116         ts->last_msg = m;
1117
1118         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1119                         spi->dev.driver->name, ts)) {
1120                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1121                 err = -EBUSY;
1122                 goto err_free_gpio;
1123         }
1124
1125         err = ads784x_hwmon_register(spi, ts);
1126         if (err)
1127                 goto err_free_irq;
1128
1129         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1130
1131         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1132          * the touchscreen, in case it's not connected.
1133          */
1134         (void) ads7846_read12_ser(&spi->dev,
1135                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1136
1137         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1138         if (err)
1139                 goto err_remove_hwmon;
1140
1141         err = input_register_device(input_dev);
1142         if (err)
1143                 goto err_remove_attr_group;
1144
1145         return 0;
1146
1147  err_remove_attr_group:
1148         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1149  err_remove_hwmon:
1150         ads784x_hwmon_unregister(spi, ts);
1151  err_free_irq:
1152         free_irq(spi->irq, ts);
1153  err_free_gpio:
1154         if (ts->gpio_pendown != -1)
1155                 gpio_free(ts->gpio_pendown);
1156  err_cleanup_filter:
1157         if (ts->filter_cleanup)
1158                 ts->filter_cleanup(ts->filter_data);
1159  err_free_mem:
1160         input_free_device(input_dev);
1161         kfree(ts);
1162         return err;
1163 }
1164
1165 static int __devexit ads7846_remove(struct spi_device *spi)
1166 {
1167         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1168
1169         ads784x_hwmon_unregister(spi, ts);
1170         input_unregister_device(ts->input);
1171
1172         ads7846_suspend(spi, PMSG_SUSPEND);
1173
1174         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1175
1176         free_irq(ts->spi->irq, ts);
1177         /* suspend left the IRQ disabled */
1178         enable_irq(ts->spi->irq);
1179
1180         if (ts->gpio_pendown != -1)
1181                 gpio_free(ts->gpio_pendown);
1182
1183         if (ts->filter_cleanup)
1184                 ts->filter_cleanup(ts->filter_data);
1185
1186         kfree(ts);
1187
1188         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1189         return 0;
1190 }
1191
1192 static struct spi_driver ads7846_driver = {
1193         .driver = {
1194                 .name   = "ads7846",
1195                 .bus    = &spi_bus_type,
1196                 .owner  = THIS_MODULE,
1197         },
1198         .probe          = ads7846_probe,
1199         .remove         = __devexit_p(ads7846_remove),
1200         .suspend        = ads7846_suspend,
1201         .resume         = ads7846_resume,
1202 };
1203
1204 static int __init ads7846_init(void)
1205 {
1206         return spi_register_driver(&ads7846_driver);
1207 }
1208 module_init(ads7846_init);
1209
1210 static void __exit ads7846_exit(void)
1211 {
1212         spi_unregister_driver(&ads7846_driver);
1213 }
1214 module_exit(ads7846_exit);
1215
1216 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1217 MODULE_LICENSE("GPL");