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 #ifdef  CONFIG_ARM
  32 #include <asm/mach-types.h>
  33 #ifdef  CONFIG_ARCH_OMAP
  34 #include <asm/arch/gpio.h>
  35 #endif
  36 #endif
  37
  38
  39 /*
  40  * This code has been heavily tested on a Nokia 770, and lightly
  41  * tested on other ads7846 devices (OSK/Mistral, Lubbock).
  42  * Support for ads7843 and ads7845 has only been stubbed in.
  43  *
  44  * IRQ handling needs a workaround because of a shortcoming in handling
  45  * edge triggered IRQs on some platforms like the OMAP1/2. These
  46  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  47  * have to maintain our own SW IRQ disabled status. This should be
  48  * removed as soon as the affected platform's IRQ handling is fixed.
  49  *
  50  * app note sbaa036 talks in more detail about accurate sampling...
  51  * that ought to help in situations like LCDs inducing noise (which
  52  * can also be helped by using synch signals) and more generally.
  53  * This driver tries to utilize the measures described in the app
  54  * note. The strength of filtering can be set in the board-* specific
  55  * files.
  56  */
  57
  58 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  59 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  60
  61 /* this driver doesn't aim at the peak continuous sample rate */
  62 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  63
  64 struct ts_event {
  65         /* For portability, we can't read 12 bit values using SPI (which
  66          * would make the controller deliver them as native byteorder u16
  67          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  68          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  69          */
  70         u16     x;
  71         u16     y;
  72         u16     z1, z2;
  73         int     ignore;
  74 };
  75
  76 struct ads7846 {
  77         struct input_dev        *input;
  78         char                    phys[32];
  79
  80         struct spi_device       *spi;
  81
  82 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  83         struct attribute_group  *attr_group;
  84         struct class_device     *hwmon;
  85 #endif
  86
  87         u16                     model;
  88         u16                     vref_delay_usecs;
  89         u16                     x_plate_ohms;
  90         u16                     pressure_max;
  91
  92         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  93         u16                     dummy;          /* for the pwrdown read */
  94         struct ts_event         tc;
  95
  96         struct spi_transfer     xfer[10];
  97         struct spi_message      msg[5];
  98         struct spi_message      *last_msg;
  99         int                     msg_idx;
 100         int                     read_cnt;
 101         int                     read_rep;
 102         int                     last_read;
 103
 104         u16                     debounce_max;
 105         u16                     debounce_tol;
 106         u16                     debounce_rep;
 107
 108         spinlock_t              lock;
 109         struct hrtimer          timer;
 110         unsigned                pendown:1;      /* P: lock */
 111         unsigned                pending:1;      /* P: lock */
 112 // FIXME remove "irq_disabled"
 113         unsigned                irq_disabled:1; /* P: lock */
 114         unsigned                disabled: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 };
 121
 122 /* leave chip selected when we're done, for quicker re-select? */
 123 #if     0
 124 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 125 #else
 126 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 127 #endif
 128
 129 /*--------------------------------------------------------------------------*/
 130
 131 /* The ADS7846 has touchscreen and other sensors.
 132  * Earlier ads784x chips are somewhat compatible.
 133  */
 134 #define ADS_START               (1 << 7)
 135 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 136 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 137 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 138 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 139 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 140 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 141 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 142 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 143 #define ADS_8_BIT               (1 << 3)
 144 #define ADS_12_BIT              (0 << 3)
 145 #define ADS_SER                 (1 << 2)        /* non-differential */
 146 #define ADS_DFR                 (0 << 2)        /* differential */
 147 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 148 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 149 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 150 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 151
 152 #define MAX_12BIT       ((1<<12)-1)
 153
 154 /* leave ADC powered up (disables penirq) between differential samples */
 155 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 156         | ADS_12_BIT | ADS_DFR | \
 157         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 158
 159 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 160 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 161 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 162
 163 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 164 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 165
 166 /* single-ended samples need to first power up reference voltage;
 167  * we leave both ADC and VREF powered
 168  */
 169 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 170         | ADS_12_BIT | ADS_SER)
 171
 172 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 173 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 174
 175 /*--------------------------------------------------------------------------*/
 176
 177 /*
 178  * Non-touchscreen sensors only use single-ended conversions.
 179  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 180  * ads7846 lets that pin be unconnected, to use internal vREF.
 181  */
 182 static unsigned vREF_mV;
 183 module_param(vREF_mV, uint, 0);
 184 MODULE_PARM_DESC(vREF_mV, "external vREF voltage, in milliVolts");
 185
 186 struct ser_req {
 187         u8                      ref_on;
 188         u8                      command;
 189         u8                      ref_off;
 190         u16                     scratch;
 191         __be16                  sample;
 192         struct spi_message      msg;
 193         struct spi_transfer     xfer[6];
 194 };
 195
 196 static void ads7846_enable(struct ads7846 *ts);
 197 static void ads7846_disable(struct ads7846 *ts);
 198
 199 static int device_suspended(struct device *dev)
 200 {
 201         struct ads7846 *ts = dev_get_drvdata(dev);
 202         return dev->power.power_state.event != PM_EVENT_ON || ts->disabled;
 203 }
 204
 205 static int ads7846_read12_ser(struct device *dev, unsigned command)
 206 {
 207         struct spi_device       *spi = to_spi_device(dev);
 208         struct ads7846          *ts = dev_get_drvdata(dev);
 209         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 210         int                     status;
 211         int                     sample;
 212         int                     use_internal;
 213
 214         if (!req)
 215                 return -ENOMEM;
 216
 217         spi_message_init(&req->msg);
 218
 219         /* FIXME boards with ads7846 might use external vref instead ... */
 220         use_internal = (ts->model == 7846);
 221
 222         /* maybe turn on internal vREF, and let it settle */
 223         if (use_internal) {
 224                 req->ref_on = REF_ON;
 225                 req->xfer[0].tx_buf = &req->ref_on;
 226                 req->xfer[0].len = 1;
 227                 spi_message_add_tail(&req->xfer[0], &req->msg);
 228
 229                 req->xfer[1].rx_buf = &req->scratch;
 230                 req->xfer[1].len = 2;
 231
 232                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 233                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 234                 spi_message_add_tail(&req->xfer[1], &req->msg);
 235         }
 236
 237         /* take sample */
 238         req->command = (u8) command;
 239         req->xfer[2].tx_buf = &req->command;
 240         req->xfer[2].len = 1;
 241         spi_message_add_tail(&req->xfer[2], &req->msg);
 242
 243         req->xfer[3].rx_buf = &req->sample;
 244         req->xfer[3].len = 2;
 245         spi_message_add_tail(&req->xfer[3], &req->msg);
 246
 247         /* REVISIT:  take a few more samples, and compare ... */
 248
 249         /* maybe off internal vREF */
 250         if (use_internal) {
 251                 req->ref_off = REF_OFF;
 252                 req->xfer[4].tx_buf = &req->ref_off;
 253                 req->xfer[4].len = 1;
 254                 spi_message_add_tail(&req->xfer[4], &req->msg);
 255
 256                 req->xfer[5].rx_buf = &req->scratch;
 257                 req->xfer[5].len = 2;
 258                 CS_CHANGE(req->xfer[5]);
 259                 spi_message_add_tail(&req->xfer[5], &req->msg);
 260         }
 261
 262         ts->irq_disabled = 1;
 263         disable_irq(spi->irq);
 264         status = spi_sync(spi, &req->msg);
 265         ts->irq_disabled = 0;
 266         enable_irq(spi->irq);
 267
 268         if (req->msg.status)
 269                 status = req->msg.status;
 270
 271         /* on-wire is a must-ignore bit, a BE12 value, then padding */
 272         sample = be16_to_cpu(req->sample);
 273         sample = sample >> 3;
 274         sample &= 0x0fff;
 275
 276         kfree(req);
 277         return status ? status : sample;
 278 }
 279
 280 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 281
 282 #define SHOW(name, var, adjust) static ssize_t \
 283 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 284 { \
 285         struct ads7846 *ts = dev_get_drvdata(dev); \
 286         ssize_t v = ads7846_read12_ser(dev, \
 287                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 288         if (v < 0) \
 289                 return v; \
 290         return sprintf(buf, "%u\n", adjust(ts, v)); \
 291 } \
 292 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 293
 294
 295 /* Sysfs conventions report temperatures in millidegrees Celcius.
 296  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 297  * accuracy scheme without calibration data.  For now we won't try either;
 298  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 299  */
 300 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 301 {
 302         return v;
 303 }
 304
 305 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 306 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 307
 308
 309 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 310  * if we know vREF.  userspace may need to scale vAUX to match the board's
 311  * external resistors; we assume that vBATT only uses the internal ones.
 312  */
 313 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 314 {
 315         unsigned retval = v;
 316
 317         /* external resistors may scale vAUX into 0..vREF */
 318         retval *= vREF_mV;
 319         retval = retval >> 12;
 320         return retval;
 321 }
 322
 323 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 324 {
 325         unsigned retval = vaux_adjust(ts, v);
 326
 327         /* ads7846 has a resistor ladder to scale this signal down */
 328         if (ts->model == 7846)
 329                 retval *= 4;
 330         return retval;
 331 }
 332
 333 SHOW(in0_input, vaux, vaux_adjust)
 334 SHOW(in1_input, vbatt, vbatt_adjust)
 335
 336
 337 static struct attribute *ads7846_attributes[] = {
 338         &dev_attr_temp0.attr,
 339         &dev_attr_temp1.attr,
 340         &dev_attr_in0_input.attr,
 341         &dev_attr_in1_input.attr,
 342         NULL,
 343 };
 344
 345 static struct attribute_group ads7846_attr_group = {
 346         .attrs = ads7846_attributes,
 347 };
 348
 349 static struct attribute *ads7843_attributes[] = {
 350         &dev_attr_in0_input.attr,
 351         &dev_attr_in1_input.attr,
 352         NULL,
 353 };
 354
 355 static struct attribute_group ads7843_attr_group = {
 356         .attrs = ads7843_attributes,
 357 };
 358
 359 static struct attribute *ads7845_attributes[] = {
 360         &dev_attr_in0_input.attr,
 361         NULL,
 362 };
 363
 364 static struct attribute_group ads7845_attr_group = {
 365         .attrs = ads7845_attributes,
 366 };
 367
 368 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 369 {
 370         struct class_device *hwmon;
 371         int err;
 372
 373         /* hwmon sensors need a reference voltage */
 374         switch (ts->model) {
 375         case 7846:
 376                 if (!vREF_mV) {
 377                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 378                         vREF_mV = 2500;
 379                 }
 380                 break;
 381         case 7845:
 382         case 7843:
 383                 if (!vREF_mV) {
 384                         dev_warn(&spi->dev,
 385                                 "external vREF for ADS%d not specified\n",
 386                                 ts->model);
 387                         return 0;
 388                 }
 389                 break;
 390         }
 391
 392         /* different chips have different sensor groups */
 393         switch (ts->model) {
 394         case 7846:
 395                 ts->attr_group = &ads7846_attr_group;
 396                 break;
 397         case 7845:
 398                 ts->attr_group = &ads7845_attr_group;
 399                 break;
 400         case 7843:
 401                 ts->attr_group = &ads7843_attr_group;
 402                 break;
 403         default:
 404                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 405                 return 0;
 406         }
 407
 408         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 409         if (err)
 410                 return err;
 411
 412         hwmon = hwmon_device_register(&spi->dev);
 413         if (IS_ERR(hwmon)) {
 414                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 415                 return PTR_ERR(hwmon);
 416         }
 417
 418         ts->hwmon = hwmon;
 419         return 0;
 420 }
 421
 422 static void ads784x_hwmon_unregister(struct spi_device *spi,
 423                                      struct ads7846 *ts)
 424 {
 425         if (ts->hwmon) {
 426                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 427                 hwmon_device_unregister(ts->hwmon);
 428         }
 429 }
 430
 431 #else
 432 static inline int ads784x_hwmon_register(struct spi_device *spi,
 433                                          struct ads7846 *ts)
 434 {
 435         return 0;
 436 }
 437
 438 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 439                                             struct ads7846 *ts)
 440 {
 441 }
 442 #endif
 443
 444 static int is_pen_down(struct device *dev)
 445 {
 446         struct ads7846  *ts = dev_get_drvdata(dev);
 447
 448         return ts->pendown;
 449 }
 450
 451 static ssize_t ads7846_pen_down_show(struct device *dev,
 452                                      struct device_attribute *attr, char *buf)
 453 {
 454         return sprintf(buf, "%u\n", is_pen_down(dev));
 455 }
 456
 457 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 458
 459 static ssize_t ads7846_disable_show(struct device *dev,
 460                                      struct device_attribute *attr, char *buf)
 461 {
 462         struct ads7846  *ts = dev_get_drvdata(dev);
 463
 464         return sprintf(buf, "%u\n", ts->disabled);
 465 }
 466
 467 static ssize_t ads7846_disable_store(struct device *dev,
 468                                      struct device_attribute *attr,
 469                                      const char *buf, size_t count)
 470 {
 471         struct ads7846 *ts = dev_get_drvdata(dev);
 472         char *endp;
 473         int i;
 474
 475         i = simple_strtoul(buf, &endp, 10);
 476         spin_lock_irq(&ts->lock);
 477
 478         if (i)
 479                 ads7846_disable(ts);
 480         else
 481                 ads7846_enable(ts);
 482
 483         spin_unlock_irq(&ts->lock);
 484
 485         return count;
 486 }
 487
 488 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 489
 490 static struct attribute *ads784x_attributes[] = {
 491         &dev_attr_pen_down.attr,
 492         &dev_attr_disable.attr,
 493         NULL,
 494 };
 495
 496 static struct attribute_group ads784x_attr_group = {
 497         .attrs = ads784x_attributes,
 498 };
 499
 500 /*--------------------------------------------------------------------------*/
 501
 502 /*
 503  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 504  * to retrieve touchscreen status.
 505  *
 506  * The SPI transfer completion callback does the real work.  It reports
 507  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 508  */
 509
 510 static void ads7846_rx(void *ads)
 511 {
 512         struct ads7846          *ts = ads;
 513         unsigned                Rt;
 514         u16                     x, y, z1, z2;
 515
 516         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 517          * on-the-wire format as part of debouncing to get stable readings.
 518          */
 519         x = ts->tc.x;
 520         y = ts->tc.y;
 521         z1 = ts->tc.z1;
 522         z2 = ts->tc.z2;
 523
 524         /* range filtering */
 525         if (x == MAX_12BIT)
 526                 x = 0;
 527
 528         if (likely(x && z1)) {
 529                 /* compute touch pressure resistance using equation #2 */
 530                 Rt = z2;
 531                 Rt -= z1;
 532                 Rt *= x;
 533                 Rt *= ts->x_plate_ohms;
 534                 Rt /= z1;
 535                 Rt = (Rt + 2047) >> 12;
 536         } else
 537                 Rt = 0;
 538
 539         /* Sample found inconsistent by debouncing or pressure is beyond
 540          * the maximum. Don't report it to user space, repeat at least
 541          * once more the measurement
 542          */
 543         if (ts->tc.ignore || Rt > ts->pressure_max) {
 544 #ifdef VERBOSE
 545                 pr_debug("%s: ignored %d pressure %d\n",
 546                         ts->spi->dev.bus_id, ts->tc.ignore, Rt);
 547 #endif
 548                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 549                               HRTIMER_REL);
 550                 return;
 551         }
 552
 553         /* NOTE: We can't rely on the pressure to determine the pen down
 554          * state, even this controller has a pressure sensor.  The pressure
 555          * value can fluctuate for quite a while after lifting the pen and
 556          * in some cases may not even settle at the expected value.
 557          *
 558          * The only safe way to check for the pen up condition is in the
 559          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 560          */
 561         if (Rt) {
 562                 struct input_dev *input = ts->input;
 563
 564                 if (!ts->pendown) {
 565                         input_report_key(input, BTN_TOUCH, 1);
 566                         ts->pendown = 1;
 567 #ifdef VERBOSE
 568                         dev_dbg(&ts->spi->dev, "DOWN\n");
 569 #endif
 570                 }
 571                 input_report_abs(input, ABS_X, x);
 572                 input_report_abs(input, ABS_Y, y);
 573                 input_report_abs(input, ABS_PRESSURE, Rt);
 574
 575                 input_sync(input);
 576 #ifdef VERBOSE
 577                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 578 #endif
 579         }
 580
 581         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD), HRTIMER_REL);
 582 }
 583
 584 static int ads7846_debounce(void *ads, int data_idx, int *val)
 585 {
 586         struct ads7846          *ts = ads;
 587
 588         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 589                 /* Start over collecting consistent readings. */
 590                 ts->read_rep = 0;
 591                 /* Repeat it, if this was the first read or the read
 592                  * wasn't consistent enough. */
 593                 if (ts->read_cnt < ts->debounce_max) {
 594                         ts->last_read = *val;
 595                         ts->read_cnt++;
 596                         return ADS7846_FILTER_REPEAT;
 597                 } else {
 598                         /* Maximum number of debouncing reached and still
 599                          * not enough number of consistent readings. Abort
 600                          * the whole sample, repeat it in the next sampling
 601                          * period.
 602                          */
 603                         ts->read_cnt = 0;
 604                         return ADS7846_FILTER_IGNORE;
 605                 }
 606         } else {
 607                 if (++ts->read_rep > ts->debounce_rep) {
 608                         /* Got a good reading for this coordinate,
 609                          * go for the next one. */
 610                         ts->read_cnt = 0;
 611                         ts->read_rep = 0;
 612                         return ADS7846_FILTER_OK;
 613                 } else {
 614                         /* Read more values that are consistent. */
 615                         ts->read_cnt++;
 616                         return ADS7846_FILTER_REPEAT;
 617                 }
 618         }
 619 }
 620
 621 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 622 {
 623         return ADS7846_FILTER_OK;
 624 }
 625
 626 static void ads7846_rx_val(void *ads)
 627 {
 628         struct ads7846 *ts = ads;
 629         struct spi_message *m;
 630         struct spi_transfer *t;
 631         u16 *rx_val;
 632         int val;
 633         int action;
 634         int status;
 635
 636         m = &ts->msg[ts->msg_idx];
 637         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 638         rx_val = t->rx_buf;
 639
 640         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 641          * built from two 8 bit values written msb-first.
 642          */
 643         val = be16_to_cpu(*rx_val) >> 3;
 644
 645         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 646         switch (action) {
 647         case ADS7846_FILTER_REPEAT:
 648                 break;
 649         case ADS7846_FILTER_IGNORE:
 650                 ts->tc.ignore = 1;
 651                 /* Last message will contain ads7846_rx() as the
 652                  * completion function.
 653                  */
 654                 m = ts->last_msg;
 655                 break;
 656         case ADS7846_FILTER_OK:
 657                 *rx_val = val;
 658                 ts->tc.ignore = 0;
 659                 m = &ts->msg[++ts->msg_idx];
 660                 break;
 661         default:
 662                 BUG();
 663         }
 664         status = spi_async(ts->spi, m);
 665         if (status)
 666                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 667                                 status);
 668 }
 669
 670 static int ads7846_timer(struct hrtimer *handle)
 671 {
 672         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 673         int             status = 0;
 674
 675         spin_lock_irq(&ts->lock);
 676
 677         if (unlikely(!ts->get_pendown_state() ||
 678                      device_suspended(&ts->spi->dev))) {
 679                 if (ts->pendown) {
 680                         struct input_dev *input = ts->input;
 681
 682                         input_report_key(input, BTN_TOUCH, 0);
 683                         input_report_abs(input, ABS_PRESSURE, 0);
 684                         input_sync(input);
 685
 686                         ts->pendown = 0;
 687 #ifdef VERBOSE
 688                         dev_dbg(&ts->spi->dev, "UP\n");
 689 #endif
 690                 }
 691
 692                 /* measurement cycle ended */
 693                 if (!device_suspended(&ts->spi->dev)) {
 694                         ts->irq_disabled = 0;
 695                         enable_irq(ts->spi->irq);
 696                 }
 697                 ts->pending = 0;
 698         } else {
 699                 /* pen is still down, continue with the measurement */
 700                 ts->msg_idx = 0;
 701                 status = spi_async(ts->spi, &ts->msg[0]);
 702                 if (status)
 703                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 704         }
 705
 706         spin_unlock_irq(&ts->lock);
 707         return HRTIMER_NORESTART;
 708 }
 709
 710 static irqreturn_t ads7846_irq(int irq, void *handle)
 711 {
 712         struct ads7846 *ts = handle;
 713         unsigned long flags;
 714
 715         spin_lock_irqsave(&ts->lock, flags);
 716         if (likely(ts->get_pendown_state())) {
 717                 if (!ts->irq_disabled) {
 718                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 719                          * like the other dispatchers:  it will report IRQs
 720                          * even after they've been disabled.  We work around
 721                          * that here.  (The "generic irq" framework may help...)
 722                          */
 723                         ts->irq_disabled = 1;
 724                         disable_irq(ts->spi->irq);
 725                         ts->pending = 1;
 726                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 727                                         HRTIMER_REL);
 728                 }
 729         }
 730         spin_unlock_irqrestore(&ts->lock, flags);
 731
 732         return IRQ_HANDLED;
 733 }
 734
 735 /*--------------------------------------------------------------------------*/
 736
 737 /* Must be called with ts->lock held */
 738 static void ads7846_disable(struct ads7846 *ts)
 739 {
 740         if (ts->disabled)
 741                 return;
 742
 743         ts->disabled = 1;
 744
 745         /* are we waiting for IRQ, or polling? */
 746         if (!ts->pending) {
 747                 ts->irq_disabled = 1;
 748                 disable_irq(ts->spi->irq);
 749         } else {
 750                 /* the timer will run at least once more, and
 751                  * leave everything in a clean state, IRQ disabled
 752                  */
 753                 while (ts->pending) {
 754                         spin_unlock_irq(&ts->lock);
 755                         msleep(1);
 756                         spin_lock_irq(&ts->lock);
 757                 }
 758         }
 759
 760         /* we know the chip's in lowpower mode since we always
 761          * leave it that way after every request
 762          */
 763
 764 }
 765
 766 /* Must be called with ts->lock held */
 767 static void ads7846_enable(struct ads7846 *ts)
 768 {
 769         if (!ts->disabled)
 770                 return;
 771
 772         ts->disabled = 0;
 773         ts->irq_disabled = 0;
 774         enable_irq(ts->spi->irq);
 775 }
 776
 777 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 778 {
 779         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 780
 781         spin_lock_irq(&ts->lock);
 782
 783         spi->dev.power.power_state = message;
 784         ads7846_disable(ts);
 785
 786         spin_unlock_irq(&ts->lock);
 787
 788         return 0;
 789
 790 }
 791
 792 static int ads7846_resume(struct spi_device *spi)
 793 {
 794         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 795
 796         spin_lock_irq(&ts->lock);
 797
 798         spi->dev.power.power_state = PMSG_ON;
 799         ads7846_enable(ts);
 800
 801         spin_unlock_irq(&ts->lock);
 802
 803         return 0;
 804 }
 805
 806 static int __devinit ads7846_probe(struct spi_device *spi)
 807 {
 808         struct ads7846                  *ts;
 809         struct input_dev                *input_dev;
 810         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 811         struct spi_message              *m;
 812         struct spi_transfer             *x;
 813         int                             vref;
 814         int                             err;
 815
 816         if (!spi->irq) {
 817                 dev_dbg(&spi->dev, "no IRQ?\n");
 818                 return -ENODEV;
 819         }
 820
 821         if (!pdata) {
 822                 dev_dbg(&spi->dev, "no platform data?\n");
 823                 return -ENODEV;
 824         }
 825
 826         /* don't exceed max specified sample rate */
 827         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 828                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 829                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 830                 return -EINVAL;
 831         }
 832
 833         /* REVISIT when the irq can be triggered active-low, or if for some
 834          * reason the touchscreen isn't hooked up, we don't need to access
 835          * the pendown state.
 836          */
 837         if (pdata->get_pendown_state == NULL) {
 838                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 839                 return -EINVAL;
 840         }
 841
 842         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 843          * that even if the hardware can do that, the SPI controller driver
 844          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 845          */
 846         spi->bits_per_word = 8;
 847         spi->mode = SPI_MODE_1;
 848         err = spi_setup(spi);
 849         if (err < 0)
 850                 return err;
 851
 852         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 853         input_dev = input_allocate_device();
 854         if (!ts || !input_dev) {
 855                 err = -ENOMEM;
 856                 goto err_free_mem;
 857         }
 858
 859         dev_set_drvdata(&spi->dev, ts);
 860         spi->dev.power.power_state = PMSG_ON;
 861
 862         ts->spi = spi;
 863         ts->input = input_dev;
 864
 865         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_REL);
 866         ts->timer.function = ads7846_timer;
 867
 868         spin_lock_init(&ts->lock);
 869
 870         ts->model = pdata->model ? : 7846;
 871         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 872         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 873         ts->pressure_max = pdata->pressure_max ? : ~0;
 874
 875         if (pdata->filter != NULL) {
 876                 if (pdata->filter_init != NULL) {
 877                         err = pdata->filter_init(pdata, &ts->filter_data);
 878                         if (err < 0)
 879                                 goto err_free_mem;
 880                 }
 881                 ts->filter = pdata->filter;
 882                 ts->filter_cleanup = pdata->filter_cleanup;
 883         } else if (pdata->debounce_max) {
 884                 ts->debounce_max = pdata->debounce_max;
 885                 if (ts->debounce_max < 2)
 886                         ts->debounce_max = 2;
 887                 ts->debounce_tol = pdata->debounce_tol;
 888                 ts->debounce_rep = pdata->debounce_rep;
 889                 ts->filter = ads7846_debounce;
 890                 ts->filter_data = ts;
 891         } else
 892                 ts->filter = ads7846_no_filter;
 893         ts->get_pendown_state = pdata->get_pendown_state;
 894
 895         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 896
 897         input_dev->name = "ADS784x Touchscreen";
 898         input_dev->phys = ts->phys;
 899         input_dev->cdev.dev = &spi->dev;
 900
 901         input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
 902         input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
 903         input_set_abs_params(input_dev, ABS_X,
 904                         pdata->x_min ? : 0,
 905                         pdata->x_max ? : MAX_12BIT,
 906                         0, 0);
 907         input_set_abs_params(input_dev, ABS_Y,
 908                         pdata->y_min ? : 0,
 909                         pdata->y_max ? : MAX_12BIT,
 910                         0, 0);
 911         input_set_abs_params(input_dev, ABS_PRESSURE,
 912                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 913
 914         vref = pdata->keep_vref_on;
 915
 916         /* set up the transfers to read touchscreen state; this assumes we
 917          * use formula #2 for pressure, not #3.
 918          */
 919         m = &ts->msg[0];
 920         x = ts->xfer;
 921
 922         spi_message_init(m);
 923
 924         /* y- still on; turn on only y+ (and ADC) */
 925         ts->read_y = READ_Y(vref);
 926         x->tx_buf = &ts->read_y;
 927         x->len = 1;
 928         spi_message_add_tail(x, m);
 929
 930         x++;
 931         x->rx_buf = &ts->tc.y;
 932         x->len = 2;
 933         spi_message_add_tail(x, m);
 934
 935         m->complete = ads7846_rx_val;
 936         m->context = ts;
 937
 938         m++;
 939         spi_message_init(m);
 940
 941         /* turn y- off, x+ on, then leave in lowpower */
 942         x++;
 943         ts->read_x = READ_X(vref);
 944         x->tx_buf = &ts->read_x;
 945         x->len = 1;
 946         spi_message_add_tail(x, m);
 947
 948         x++;
 949         x->rx_buf = &ts->tc.x;
 950         x->len = 2;
 951         spi_message_add_tail(x, m);
 952
 953         m->complete = ads7846_rx_val;
 954         m->context = ts;
 955
 956         /* turn y+ off, x- on; we'll use formula #2 */
 957         if (ts->model == 7846) {
 958                 m++;
 959                 spi_message_init(m);
 960
 961                 x++;
 962                 ts->read_z1 = READ_Z1(vref);
 963                 x->tx_buf = &ts->read_z1;
 964                 x->len = 1;
 965                 spi_message_add_tail(x, m);
 966
 967                 x++;
 968                 x->rx_buf = &ts->tc.z1;
 969                 x->len = 2;
 970                 spi_message_add_tail(x, m);
 971
 972                 m->complete = ads7846_rx_val;
 973                 m->context = ts;
 974
 975                 m++;
 976                 spi_message_init(m);
 977
 978                 x++;
 979                 ts->read_z2 = READ_Z2(vref);
 980                 x->tx_buf = &ts->read_z2;
 981                 x->len = 1;
 982                 spi_message_add_tail(x, m);
 983
 984                 x++;
 985                 x->rx_buf = &ts->tc.z2;
 986                 x->len = 2;
 987                 spi_message_add_tail(x, m);
 988
 989                 m->complete = ads7846_rx_val;
 990                 m->context = ts;
 991         }
 992
 993         /* power down */
 994         m++;
 995         spi_message_init(m);
 996
 997         x++;
 998         ts->pwrdown = PWRDOWN;
 999         x->tx_buf = &ts->pwrdown;
1000         x->len = 1;
1001         spi_message_add_tail(x, m);
1002
1003         x++;
1004         x->rx_buf = &ts->dummy;
1005         x->len = 2;
1006         CS_CHANGE(*x);
1007         spi_message_add_tail(x, m);
1008
1009         m->complete = ads7846_rx;
1010         m->context = ts;
1011
1012         ts->last_msg = m;
1013
1014         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1015                         spi->dev.driver->name, ts)) {
1016                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1017                 err = -EBUSY;
1018                 goto err_cleanup_filter;
1019         }
1020
1021         err = ads784x_hwmon_register(spi, ts);
1022         if (err)
1023                 goto err_free_irq;
1024
1025         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1026
1027         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1028          * the touchscreen, in case it's not connected.
1029          */
1030         (void) ads7846_read12_ser(&spi->dev,
1031                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1032
1033         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1034         if (err)
1035                 goto err_remove_hwmon;
1036
1037         err = input_register_device(input_dev);
1038         if (err)
1039                 goto err_remove_attr_group;
1040
1041         return 0;
1042
1043  err_remove_attr_group:
1044         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1045  err_remove_hwmon:
1046         ads784x_hwmon_unregister(spi, ts);
1047  err_free_irq:
1048         free_irq(spi->irq, ts);
1049  err_cleanup_filter:
1050         if (ts->filter_cleanup)
1051                 ts->filter_cleanup(ts->filter_data);
1052  err_free_mem:
1053         input_free_device(input_dev);
1054         kfree(ts);
1055         return err;
1056 }
1057
1058 static int __devexit ads7846_remove(struct spi_device *spi)
1059 {
1060         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1061
1062         ads784x_hwmon_unregister(spi, ts);
1063         input_unregister_device(ts->input);
1064
1065         ads7846_suspend(spi, PMSG_SUSPEND);
1066
1067         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1068
1069         free_irq(ts->spi->irq, ts);
1070         /* suspend left the IRQ disabled */
1071         enable_irq(ts->spi->irq);
1072
1073         if (ts->filter_cleanup)
1074                 ts->filter_cleanup(ts->filter_data);
1075
1076         kfree(ts);
1077
1078         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1079         return 0;
1080 }
1081
1082 static struct spi_driver ads7846_driver = {
1083         .driver = {
1084                 .name   = "ads7846",
1085                 .bus    = &spi_bus_type,
1086                 .owner  = THIS_MODULE,
1087         },
1088         .probe          = ads7846_probe,
1089         .remove         = __devexit_p(ads7846_remove),
1090         .suspend        = ads7846_suspend,
1091         .resume         = ads7846_resume,
1092 };
1093
1094 static int __init ads7846_init(void)
1095 {
1096         /* grr, board-specific init should stay out of drivers!! */
1097
1098 #ifdef  CONFIG_ARCH_OMAP
1099         if (machine_is_omap_osk()) {
1100                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
1101                 omap_request_gpio(4);
1102                 omap_set_gpio_direction(4, 1);
1103                 omap_request_gpio(6);
1104                 omap_set_gpio_direction(6, 1);
1105         }
1106         // also TI 1510 Innovator, bitbanging through FPGA
1107         // also Nokia 770
1108         // also Palm Tungsten T2
1109 #endif
1110
1111         // PXA:
1112         // also Dell Axim X50
1113         // also HP iPaq H191x/H192x/H415x/H435x
1114         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
1115         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
1116
1117         // Atmel at91sam9261-EK uses ads7843
1118
1119         // also various AMD Au1x00 devel boards
1120
1121         return spi_register_driver(&ads7846_driver);
1122 }
1123 module_init(ads7846_init);
1124
1125 static void __exit ads7846_exit(void)
1126 {
1127         spi_unregister_driver(&ads7846_driver);
1128
1129 #ifdef  CONFIG_ARCH_OMAP
1130         if (machine_is_omap_osk()) {
1131                 omap_free_gpio(4);
1132                 omap_free_gpio(6);
1133         }
1134 #endif
1135
1136 }
1137 module_exit(ads7846_exit);
1138
1139 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1140 MODULE_LICENSE("GPL");