SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 <linux/regulator/consumer.h>
  31 #include <asm/irq.h>
  32
  33 /*
  34  * This code has been heavily tested on a Nokia 770, and lightly
  35  * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
  36  * TSC2046 is just newer ads7846 silicon.
  37  * Support for ads7843 tested on Atmel at91sam926x-EK.
  38  * Support for ads7845 has only been stubbed in.
  39  *
  40  * IRQ handling needs a workaround because of a shortcoming in handling
  41  * edge triggered IRQs on some platforms like the OMAP1/2. These
  42  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  43  * have to maintain our own SW IRQ disabled status. This should be
  44  * removed as soon as the affected platform's IRQ handling is fixed.
  45  *
  46  * App note sbaa036 talks in more detail about accurate sampling...
  47  * that ought to help in situations like LCDs inducing noise (which
  48  * can also be helped by using synch signals) and more generally.
  49  * This driver tries to utilize the measures described in the app
  50  * note. The strength of filtering can be set in the board-* specific
  51  * files.
  52  */
  53
  54 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  55 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  56
  57 /* this driver doesn't aim at the peak continuous sample rate */
  58 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  59
  60 struct ts_event {
  61         /* For portability, we can't read 12 bit values using SPI (which
  62          * would make the controller deliver them as native byteorder u16
  63          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  64          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  65          */
  66         u16     x;
  67         u16     y;
  68         u16     z1, z2;
  69         int     ignore;
  70 };
  71
  72 /*
  73  * We allocate this separately to avoid cache line sharing issues when
  74  * driver is used with DMA-based SPI controllers (like atmel_spi) on
  75  * systems where main memory is not DMA-coherent (most non-x86 boards).
  76  */
  77 struct ads7846_packet {
  78         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  79         u16                     dummy;          /* for the pwrdown read */
  80         struct ts_event         tc;
  81 };
  82
  83 struct ads7846 {
  84         struct input_dev        *input;
  85         char                    phys[32];
  86         char                    name[32];
  87
  88         struct spi_device       *spi;
  89         struct regulator        *reg;
  90
  91 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  92         struct attribute_group  *attr_group;
  93         struct device           *hwmon;
  94 #endif
  95
  96         u16                     model;
  97         u16                     vref_mv;
  98         u16                     vref_delay_usecs;
  99         u16                     x_plate_ohms;
 100         u16                     pressure_max;
 101
 102         bool                    swap_xy;
 103
 104         struct ads7846_packet   *packet;
 105
 106         struct spi_transfer     xfer[18];
 107         struct spi_message      msg[5];
 108         struct spi_message      *last_msg;
 109         int                     msg_idx;
 110         int                     read_cnt;
 111         int                     read_rep;
 112         int                     last_read;
 113
 114         u16                     debounce_max;
 115         u16                     debounce_tol;
 116         u16                     debounce_rep;
 117
 118         u16                     penirq_recheck_delay_usecs;
 119
 120         spinlock_t              lock;
 121         struct hrtimer          timer;
 122         unsigned                pendown:1;      /* P: lock */
 123         unsigned                pending:1;      /* P: lock */
 124 // FIXME remove "irq_disabled"
 125         unsigned                irq_disabled:1; /* P: lock */
 126         unsigned                disabled:1;
 127         unsigned                is_suspended:1;
 128
 129         int                     (*filter)(void *data, int data_idx, int *val);
 130         void                    *filter_data;
 131         void                    (*filter_cleanup)(void *data);
 132         int                     (*get_pendown_state)(void);
 133         int                     gpio_pendown;
 134
 135         void                    (*wait_for_sync)(void);
 136 };
 137
 138 /* leave chip selected when we're done, for quicker re-select? */
 139 #if     0
 140 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 141 #else
 142 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 143 #endif
 144
 145 /*--------------------------------------------------------------------------*/
 146
 147 /* The ADS7846 has touchscreen and other sensors.
 148  * Earlier ads784x chips are somewhat compatible.
 149  */
 150 #define ADS_START               (1 << 7)
 151 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 152 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 153 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 154 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 155 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 156 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 157 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 158 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 159 #define ADS_8_BIT               (1 << 3)
 160 #define ADS_12_BIT              (0 << 3)
 161 #define ADS_SER                 (1 << 2)        /* non-differential */
 162 #define ADS_DFR                 (0 << 2)        /* differential */
 163 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 164 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 165 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 166 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 167
 168 #define MAX_12BIT       ((1<<12)-1)
 169
 170 /* leave ADC powered up (disables penirq) between differential samples */
 171 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 172         | ADS_12_BIT | ADS_DFR | \
 173         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 174
 175 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 176 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 177 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 178
 179 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 180 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 181
 182 /* single-ended samples need to first power up reference voltage;
 183  * we leave both ADC and VREF powered
 184  */
 185 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 186         | ADS_12_BIT | ADS_SER)
 187
 188 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 189 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 190
 191 /*--------------------------------------------------------------------------*/
 192
 193 /*
 194  * Non-touchscreen sensors only use single-ended conversions.
 195  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 196  * ads7846 lets that pin be unconnected, to use internal vREF.
 197  */
 198
 199 struct ser_req {
 200         u8                      ref_on;
 201         u8                      command;
 202         u8                      ref_off;
 203         u16                     scratch;
 204         __be16                  sample;
 205         struct spi_message      msg;
 206         struct spi_transfer     xfer[6];
 207 };
 208
 209 static void ads7846_enable(struct ads7846 *ts);
 210 static void ads7846_disable(struct ads7846 *ts);
 211
 212 static int device_suspended(struct device *dev)
 213 {
 214         struct ads7846 *ts = dev_get_drvdata(dev);
 215         return ts->is_suspended || ts->disabled;
 216 }
 217
 218 static int ads7846_read12_ser(struct device *dev, unsigned command)
 219 {
 220         struct spi_device       *spi = to_spi_device(dev);
 221         struct ads7846          *ts = dev_get_drvdata(dev);
 222         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 223         int                     status;
 224         int                     use_internal;
 225
 226         if (!req)
 227                 return -ENOMEM;
 228
 229         spi_message_init(&req->msg);
 230
 231         /* FIXME boards with ads7846 might use external vref instead ... */
 232         use_internal = (ts->model == 7846);
 233
 234         /* maybe turn on internal vREF, and let it settle */
 235         if (use_internal) {
 236                 req->ref_on = REF_ON;
 237                 req->xfer[0].tx_buf = &req->ref_on;
 238                 req->xfer[0].len = 1;
 239                 spi_message_add_tail(&req->xfer[0], &req->msg);
 240
 241                 req->xfer[1].rx_buf = &req->scratch;
 242                 req->xfer[1].len = 2;
 243
 244                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 245                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 246                 spi_message_add_tail(&req->xfer[1], &req->msg);
 247         }
 248
 249         /* take sample */
 250         req->command = (u8) command;
 251         req->xfer[2].tx_buf = &req->command;
 252         req->xfer[2].len = 1;
 253         spi_message_add_tail(&req->xfer[2], &req->msg);
 254
 255         req->xfer[3].rx_buf = &req->sample;
 256         req->xfer[3].len = 2;
 257         spi_message_add_tail(&req->xfer[3], &req->msg);
 258
 259         /* REVISIT:  take a few more samples, and compare ... */
 260
 261         /* converter in low power mode & enable PENIRQ */
 262         req->ref_off = PWRDOWN;
 263         req->xfer[4].tx_buf = &req->ref_off;
 264         req->xfer[4].len = 1;
 265         spi_message_add_tail(&req->xfer[4], &req->msg);
 266
 267         req->xfer[5].rx_buf = &req->scratch;
 268         req->xfer[5].len = 2;
 269         CS_CHANGE(req->xfer[5]);
 270         spi_message_add_tail(&req->xfer[5], &req->msg);
 271
 272         ts->irq_disabled = 1;
 273         disable_irq(spi->irq);
 274         status = spi_sync(spi, &req->msg);
 275         ts->irq_disabled = 0;
 276         enable_irq(spi->irq);
 277
 278         if (status == 0) {
 279                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 280                 status = be16_to_cpu(req->sample);
 281                 status = status >> 3;
 282                 status &= 0x0fff;
 283         }
 284
 285         kfree(req);
 286         return status;
 287 }
 288
 289 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 290
 291 #define SHOW(name, var, adjust) static ssize_t \
 292 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 293 { \
 294         struct ads7846 *ts = dev_get_drvdata(dev); \
 295         ssize_t v = ads7846_read12_ser(dev, \
 296                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 297         if (v < 0) \
 298                 return v; \
 299         return sprintf(buf, "%u\n", adjust(ts, v)); \
 300 } \
 301 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 302
 303
 304 /* Sysfs conventions report temperatures in millidegrees Celsius.
 305  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 306  * accuracy scheme without calibration data.  For now we won't try either;
 307  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 308  */
 309 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 310 {
 311         return v;
 312 }
 313
 314 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 315 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 316
 317
 318 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 319  * if we know vREF.  userspace may need to scale vAUX to match the board's
 320  * external resistors; we assume that vBATT only uses the internal ones.
 321  */
 322 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 323 {
 324         unsigned retval = v;
 325
 326         /* external resistors may scale vAUX into 0..vREF */
 327         retval *= ts->vref_mv;
 328         retval = retval >> 12;
 329         return retval;
 330 }
 331
 332 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 333 {
 334         unsigned retval = vaux_adjust(ts, v);
 335
 336         /* ads7846 has a resistor ladder to scale this signal down */
 337         if (ts->model == 7846)
 338                 retval *= 4;
 339         return retval;
 340 }
 341
 342 SHOW(in0_input, vaux, vaux_adjust)
 343 SHOW(in1_input, vbatt, vbatt_adjust)
 344
 345
 346 static struct attribute *ads7846_attributes[] = {
 347         &dev_attr_temp0.attr,
 348         &dev_attr_temp1.attr,
 349         &dev_attr_in0_input.attr,
 350         &dev_attr_in1_input.attr,
 351         NULL,
 352 };
 353
 354 static struct attribute_group ads7846_attr_group = {
 355         .attrs = ads7846_attributes,
 356 };
 357
 358 static struct attribute *ads7843_attributes[] = {
 359         &dev_attr_in0_input.attr,
 360         &dev_attr_in1_input.attr,
 361         NULL,
 362 };
 363
 364 static struct attribute_group ads7843_attr_group = {
 365         .attrs = ads7843_attributes,
 366 };
 367
 368 static struct attribute *ads7845_attributes[] = {
 369         &dev_attr_in0_input.attr,
 370         NULL,
 371 };
 372
 373 static struct attribute_group ads7845_attr_group = {
 374         .attrs = ads7845_attributes,
 375 };
 376
 377 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 378 {
 379         struct device *hwmon;
 380         int err;
 381
 382         /* hwmon sensors need a reference voltage */
 383         switch (ts->model) {
 384         case 7846:
 385                 if (!ts->vref_mv) {
 386                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 387                         ts->vref_mv = 2500;
 388                 }
 389                 break;
 390         case 7845:
 391         case 7843:
 392                 if (!ts->vref_mv) {
 393                         dev_warn(&spi->dev,
 394                                 "external vREF for ADS%d not specified\n",
 395                                 ts->model);
 396                         return 0;
 397                 }
 398                 break;
 399         }
 400
 401         /* different chips have different sensor groups */
 402         switch (ts->model) {
 403         case 7846:
 404                 ts->attr_group = &ads7846_attr_group;
 405                 break;
 406         case 7845:
 407                 ts->attr_group = &ads7845_attr_group;
 408                 break;
 409         case 7843:
 410                 ts->attr_group = &ads7843_attr_group;
 411                 break;
 412         default:
 413                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 414                 return 0;
 415         }
 416
 417         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 418         if (err)
 419                 return err;
 420
 421         hwmon = hwmon_device_register(&spi->dev);
 422         if (IS_ERR(hwmon)) {
 423                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 424                 return PTR_ERR(hwmon);
 425         }
 426
 427         ts->hwmon = hwmon;
 428         return 0;
 429 }
 430
 431 static void ads784x_hwmon_unregister(struct spi_device *spi,
 432                                      struct ads7846 *ts)
 433 {
 434         if (ts->hwmon) {
 435                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 436                 hwmon_device_unregister(ts->hwmon);
 437         }
 438 }
 439
 440 #else
 441 static inline int ads784x_hwmon_register(struct spi_device *spi,
 442                                          struct ads7846 *ts)
 443 {
 444         return 0;
 445 }
 446
 447 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 448                                             struct ads7846 *ts)
 449 {
 450 }
 451 #endif
 452
 453 static int is_pen_down(struct device *dev)
 454 {
 455         struct ads7846  *ts = dev_get_drvdata(dev);
 456
 457         return ts->pendown;
 458 }
 459
 460 static ssize_t ads7846_pen_down_show(struct device *dev,
 461                                      struct device_attribute *attr, char *buf)
 462 {
 463         return sprintf(buf, "%u\n", is_pen_down(dev));
 464 }
 465
 466 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 467
 468 static ssize_t ads7846_disable_show(struct device *dev,
 469                                      struct device_attribute *attr, char *buf)
 470 {
 471         struct ads7846  *ts = dev_get_drvdata(dev);
 472
 473         return sprintf(buf, "%u\n", ts->disabled);
 474 }
 475
 476 static ssize_t ads7846_disable_store(struct device *dev,
 477                                      struct device_attribute *attr,
 478                                      const char *buf, size_t count)
 479 {
 480         struct ads7846 *ts = dev_get_drvdata(dev);
 481         unsigned long i;
 482
 483         if (strict_strtoul(buf, 10, &i))
 484                 return -EINVAL;
 485
 486         spin_lock_irq(&ts->lock);
 487
 488         if (i)
 489                 ads7846_disable(ts);
 490         else
 491                 ads7846_enable(ts);
 492
 493         spin_unlock_irq(&ts->lock);
 494
 495         return count;
 496 }
 497
 498 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 499
 500 static struct attribute *ads784x_attributes[] = {
 501         &dev_attr_pen_down.attr,
 502         &dev_attr_disable.attr,
 503         NULL,
 504 };
 505
 506 static struct attribute_group ads784x_attr_group = {
 507         .attrs = ads784x_attributes,
 508 };
 509
 510 /*--------------------------------------------------------------------------*/
 511
 512 static int get_pendown_state(struct ads7846 *ts)
 513 {
 514         if (ts->get_pendown_state)
 515                 return ts->get_pendown_state();
 516
 517         return !gpio_get_value(ts->gpio_pendown);
 518 }
 519
 520 static void null_wait_for_sync(void)
 521 {
 522 }
 523
 524 /*
 525  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 526  * to retrieve touchscreen status.
 527  *
 528  * The SPI transfer completion callback does the real work.  It reports
 529  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 530  */
 531
 532 static void ads7846_rx(void *ads)
 533 {
 534         struct ads7846          *ts = ads;
 535         struct ads7846_packet   *packet = ts->packet;
 536         unsigned                Rt;
 537         u16                     x, y, z1, z2;
 538
 539         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 540          * on-the-wire format as part of debouncing to get stable readings.
 541          */
 542         x = packet->tc.x;
 543         y = packet->tc.y;
 544         z1 = packet->tc.z1;
 545         z2 = packet->tc.z2;
 546
 547         /* range filtering */
 548         if (x == MAX_12BIT)
 549                 x = 0;
 550
 551         if (ts->model == 7843) {
 552                 Rt = ts->pressure_max / 2;
 553         } else if (likely(x && z1)) {
 554                 /* compute touch pressure resistance using equation #2 */
 555                 Rt = z2;
 556                 Rt -= z1;
 557                 Rt *= x;
 558                 Rt *= ts->x_plate_ohms;
 559                 Rt /= z1;
 560                 Rt = (Rt + 2047) >> 12;
 561         } else {
 562                 Rt = 0;
 563         }
 564
 565         /* Sample found inconsistent by debouncing or pressure is beyond
 566          * the maximum. Don't report it to user space, repeat at least
 567          * once more the measurement
 568          */
 569         if (packet->tc.ignore || Rt > ts->pressure_max) {
 570                 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
 571                          packet->tc.ignore, Rt);
 572                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 573                               HRTIMER_MODE_REL);
 574                 return;
 575         }
 576
 577         /* Maybe check the pendown state before reporting. This discards
 578          * false readings when the pen is lifted.
 579          */
 580         if (ts->penirq_recheck_delay_usecs) {
 581                 udelay(ts->penirq_recheck_delay_usecs);
 582                 if (!get_pendown_state(ts))
 583                         Rt = 0;
 584         }
 585
 586         /* NOTE: We can't rely on the pressure to determine the pen down
 587          * state, even this controller has a pressure sensor.  The pressure
 588          * value can fluctuate for quite a while after lifting the pen and
 589          * in some cases may not even settle at the expected value.
 590          *
 591          * The only safe way to check for the pen up condition is in the
 592          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 593          */
 594         if (Rt) {
 595                 struct input_dev *input = ts->input;
 596
 597                 if (!ts->pendown) {
 598                         input_report_key(input, BTN_TOUCH, 1);
 599                         ts->pendown = 1;
 600                         dev_vdbg(&ts->spi->dev, "DOWN\n");
 601                 }
 602
 603                 if (ts->swap_xy)
 604                         swap(x, y);
 605
 606                 input_report_abs(input, ABS_X, x);
 607                 input_report_abs(input, ABS_Y, y);
 608                 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
 609
 610                 input_sync(input);
 611                 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 612         }
 613
 614         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 615                         HRTIMER_MODE_REL);
 616 }
 617
 618 static int ads7846_debounce(void *ads, int data_idx, int *val)
 619 {
 620         struct ads7846          *ts = ads;
 621
 622         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 623                 /* Start over collecting consistent readings. */
 624                 ts->read_rep = 0;
 625                 /* Repeat it, if this was the first read or the read
 626                  * wasn't consistent enough. */
 627                 if (ts->read_cnt < ts->debounce_max) {
 628                         ts->last_read = *val;
 629                         ts->read_cnt++;
 630                         return ADS7846_FILTER_REPEAT;
 631                 } else {
 632                         /* Maximum number of debouncing reached and still
 633                          * not enough number of consistent readings. Abort
 634                          * the whole sample, repeat it in the next sampling
 635                          * period.
 636                          */
 637                         ts->read_cnt = 0;
 638                         return ADS7846_FILTER_IGNORE;
 639                 }
 640         } else {
 641                 if (++ts->read_rep > ts->debounce_rep) {
 642                         /* Got a good reading for this coordinate,
 643                          * go for the next one. */
 644                         ts->read_cnt = 0;
 645                         ts->read_rep = 0;
 646                         return ADS7846_FILTER_OK;
 647                 } else {
 648                         /* Read more values that are consistent. */
 649                         ts->read_cnt++;
 650                         return ADS7846_FILTER_REPEAT;
 651                 }
 652         }
 653 }
 654
 655 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 656 {
 657         return ADS7846_FILTER_OK;
 658 }
 659
 660 static void ads7846_rx_val(void *ads)
 661 {
 662         struct ads7846 *ts = ads;
 663         struct ads7846_packet *packet = ts->packet;
 664         struct spi_message *m;
 665         struct spi_transfer *t;
 666         int val;
 667         int action;
 668         int status;
 669
 670         m = &ts->msg[ts->msg_idx];
 671         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 672
 673         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 674          * built from two 8 bit values written msb-first.
 675          */
 676         val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
 677
 678         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 679         switch (action) {
 680         case ADS7846_FILTER_REPEAT:
 681                 break;
 682         case ADS7846_FILTER_IGNORE:
 683                 packet->tc.ignore = 1;
 684                 /* Last message will contain ads7846_rx() as the
 685                  * completion function.
 686                  */
 687                 m = ts->last_msg;
 688                 break;
 689         case ADS7846_FILTER_OK:
 690                 *(u16 *)t->rx_buf = val;
 691                 packet->tc.ignore = 0;
 692                 m = &ts->msg[++ts->msg_idx];
 693                 break;
 694         default:
 695                 BUG();
 696         }
 697         ts->wait_for_sync();
 698         status = spi_async(ts->spi, m);
 699         if (status)
 700                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 701                                 status);
 702 }
 703
 704 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 705 {
 706         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 707         int             status = 0;
 708
 709         spin_lock(&ts->lock);
 710
 711         if (unlikely(!get_pendown_state(ts) ||
 712                      device_suspended(&ts->spi->dev))) {
 713                 if (ts->pendown) {
 714                         struct input_dev *input = ts->input;
 715
 716                         input_report_key(input, BTN_TOUCH, 0);
 717                         input_report_abs(input, ABS_PRESSURE, 0);
 718                         input_sync(input);
 719
 720                         ts->pendown = 0;
 721                         dev_vdbg(&ts->spi->dev, "UP\n");
 722                 }
 723
 724                 /* measurement cycle ended */
 725                 if (!device_suspended(&ts->spi->dev)) {
 726                         ts->irq_disabled = 0;
 727                         enable_irq(ts->spi->irq);
 728                 }
 729                 ts->pending = 0;
 730         } else {
 731                 /* pen is still down, continue with the measurement */
 732                 ts->msg_idx = 0;
 733                 ts->wait_for_sync();
 734                 status = spi_async(ts->spi, &ts->msg[0]);
 735                 if (status)
 736                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 737         }
 738
 739         spin_unlock(&ts->lock);
 740         return HRTIMER_NORESTART;
 741 }
 742
 743 static irqreturn_t ads7846_irq(int irq, void *handle)
 744 {
 745         struct ads7846 *ts = handle;
 746         unsigned long flags;
 747
 748         spin_lock_irqsave(&ts->lock, flags);
 749         if (likely(get_pendown_state(ts))) {
 750                 if (!ts->irq_disabled) {
 751                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 752                          * like the other dispatchers:  it will report IRQs
 753                          * even after they've been disabled.  We work around
 754                          * that here.  (The "generic irq" framework may help...)
 755                          */
 756                         ts->irq_disabled = 1;
 757                         disable_irq_nosync(ts->spi->irq);
 758                         ts->pending = 1;
 759                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 760                                         HRTIMER_MODE_REL);
 761                 }
 762         }
 763         spin_unlock_irqrestore(&ts->lock, flags);
 764
 765         return IRQ_HANDLED;
 766 }
 767
 768 /*--------------------------------------------------------------------------*/
 769
 770 /* Must be called with ts->lock held */
 771 static void ads7846_disable(struct ads7846 *ts)
 772 {
 773         if (ts->disabled)
 774                 return;
 775
 776         ts->disabled = 1;
 777
 778         /* are we waiting for IRQ, or polling? */
 779         if (!ts->pending) {
 780                 ts->irq_disabled = 1;
 781                 disable_irq(ts->spi->irq);
 782         } else {
 783                 /* the timer will run at least once more, and
 784                  * leave everything in a clean state, IRQ disabled
 785                  */
 786                 while (ts->pending) {
 787                         spin_unlock_irq(&ts->lock);
 788                         msleep(1);
 789                         spin_lock_irq(&ts->lock);
 790                 }
 791         }
 792
 793         regulator_disable(ts->reg);
 794
 795         /* we know the chip's in lowpower mode since we always
 796          * leave it that way after every request
 797          */
 798 }
 799
 800 /* Must be called with ts->lock held */
 801 static void ads7846_enable(struct ads7846 *ts)
 802 {
 803         if (!ts->disabled)
 804                 return;
 805
 806         regulator_enable(ts->reg);
 807
 808         ts->disabled = 0;
 809         ts->irq_disabled = 0;
 810         enable_irq(ts->spi->irq);
 811 }
 812
 813 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 814 {
 815         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 816
 817         spin_lock_irq(&ts->lock);
 818
 819         ts->is_suspended = 1;
 820         ads7846_disable(ts);
 821
 822         spin_unlock_irq(&ts->lock);
 823
 824         return 0;
 825
 826 }
 827
 828 static int ads7846_resume(struct spi_device *spi)
 829 {
 830         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 831
 832         spin_lock_irq(&ts->lock);
 833
 834         ts->is_suspended = 0;
 835         ads7846_enable(ts);
 836
 837         spin_unlock_irq(&ts->lock);
 838
 839         return 0;
 840 }
 841
 842 static int __devinit setup_pendown(struct spi_device *spi, struct ads7846 *ts)
 843 {
 844         struct ads7846_platform_data *pdata = spi->dev.platform_data;
 845         int err;
 846
 847         /* REVISIT when the irq can be triggered active-low, or if for some
 848          * reason the touchscreen isn't hooked up, we don't need to access
 849          * the pendown state.
 850          */
 851         if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
 852                 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
 853                 return -EINVAL;
 854         }
 855
 856         if (pdata->get_pendown_state) {
 857                 ts->get_pendown_state = pdata->get_pendown_state;
 858                 return 0;
 859         }
 860
 861         err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
 862         if (err) {
 863                 dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
 864                                 pdata->gpio_pendown);
 865                 return err;
 866         }
 867
 868         ts->gpio_pendown = pdata->gpio_pendown;
 869         return 0;
 870 }
 871
 872 static int __devinit ads7846_probe(struct spi_device *spi)
 873 {
 874         struct ads7846                  *ts;
 875         struct ads7846_packet           *packet;
 876         struct input_dev                *input_dev;
 877         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 878         struct spi_message              *m;
 879         struct spi_transfer             *x;
 880         int                             vref;
 881         int                             err;
 882
 883         if (!spi->irq) {
 884                 dev_dbg(&spi->dev, "no IRQ?\n");
 885                 return -ENODEV;
 886         }
 887
 888         if (!pdata) {
 889                 dev_dbg(&spi->dev, "no platform data?\n");
 890                 return -ENODEV;
 891         }
 892
 893         /* don't exceed max specified sample rate */
 894         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 895                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 896                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 897                 return -EINVAL;
 898         }
 899
 900         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 901          * that even if the hardware can do that, the SPI controller driver
 902          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 903          */
 904         spi->bits_per_word = 8;
 905         spi->mode = SPI_MODE_0;
 906         err = spi_setup(spi);
 907         if (err < 0)
 908                 return err;
 909
 910         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 911         packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
 912         input_dev = input_allocate_device();
 913         if (!ts || !packet || !input_dev) {
 914                 err = -ENOMEM;
 915                 goto err_free_mem;
 916         }
 917
 918         dev_set_drvdata(&spi->dev, ts);
 919
 920         ts->packet = packet;
 921         ts->spi = spi;
 922         ts->input = input_dev;
 923         ts->vref_mv = pdata->vref_mv;
 924         ts->swap_xy = pdata->swap_xy;
 925
 926         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 927         ts->timer.function = ads7846_timer;
 928
 929         spin_lock_init(&ts->lock);
 930
 931         ts->model = pdata->model ? : 7846;
 932         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 933         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 934         ts->pressure_max = pdata->pressure_max ? : ~0;
 935
 936         if (pdata->filter != NULL) {
 937                 if (pdata->filter_init != NULL) {
 938                         err = pdata->filter_init(pdata, &ts->filter_data);
 939                         if (err < 0)
 940                                 goto err_free_mem;
 941                 }
 942                 ts->filter = pdata->filter;
 943                 ts->filter_cleanup = pdata->filter_cleanup;
 944         } else if (pdata->debounce_max) {
 945                 ts->debounce_max = pdata->debounce_max;
 946                 if (ts->debounce_max < 2)
 947                         ts->debounce_max = 2;
 948                 ts->debounce_tol = pdata->debounce_tol;
 949                 ts->debounce_rep = pdata->debounce_rep;
 950                 ts->filter = ads7846_debounce;
 951                 ts->filter_data = ts;
 952         } else
 953                 ts->filter = ads7846_no_filter;
 954
 955         err = setup_pendown(spi, ts);
 956         if (err)
 957                 goto err_cleanup_filter;
 958
 959         if (pdata->penirq_recheck_delay_usecs)
 960                 ts->penirq_recheck_delay_usecs =
 961                                 pdata->penirq_recheck_delay_usecs;
 962
 963         ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
 964
 965         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
 966         snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
 967
 968         input_dev->name = ts->name;
 969         input_dev->phys = ts->phys;
 970         input_dev->dev.parent = &spi->dev;
 971
 972         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 973         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 974         input_set_abs_params(input_dev, ABS_X,
 975                         pdata->x_min ? : 0,
 976                         pdata->x_max ? : MAX_12BIT,
 977                         0, 0);
 978         input_set_abs_params(input_dev, ABS_Y,
 979                         pdata->y_min ? : 0,
 980                         pdata->y_max ? : MAX_12BIT,
 981                         0, 0);
 982         input_set_abs_params(input_dev, ABS_PRESSURE,
 983                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 984
 985         vref = pdata->keep_vref_on;
 986
 987         /* set up the transfers to read touchscreen state; this assumes we
 988          * use formula #2 for pressure, not #3.
 989          */
 990         m = &ts->msg[0];
 991         x = ts->xfer;
 992
 993         spi_message_init(m);
 994
 995         /* y- still on; turn on only y+ (and ADC) */
 996         packet->read_y = READ_Y(vref);
 997         x->tx_buf = &packet->read_y;
 998         x->len = 1;
 999         spi_message_add_tail(x, m);
1000
1001         x++;
1002         x->rx_buf = &packet->tc.y;
1003         x->len = 2;
1004         spi_message_add_tail(x, m);
1005
1006         /* the first sample after switching drivers can be low quality;
1007          * optionally discard it, using a second one after the signals
1008          * have had enough time to stabilize.
1009          */
1010         if (pdata->settle_delay_usecs) {
1011                 x->delay_usecs = pdata->settle_delay_usecs;
1012
1013                 x++;
1014                 x->tx_buf = &packet->read_y;
1015                 x->len = 1;
1016                 spi_message_add_tail(x, m);
1017
1018                 x++;
1019                 x->rx_buf = &packet->tc.y;
1020                 x->len = 2;
1021                 spi_message_add_tail(x, m);
1022         }
1023
1024         m->complete = ads7846_rx_val;
1025         m->context = ts;
1026
1027         m++;
1028         spi_message_init(m);
1029
1030         /* turn y- off, x+ on, then leave in lowpower */
1031         x++;
1032         packet->read_x = READ_X(vref);
1033         x->tx_buf = &packet->read_x;
1034         x->len = 1;
1035         spi_message_add_tail(x, m);
1036
1037         x++;
1038         x->rx_buf = &packet->tc.x;
1039         x->len = 2;
1040         spi_message_add_tail(x, m);
1041
1042         /* ... maybe discard first sample ... */
1043         if (pdata->settle_delay_usecs) {
1044                 x->delay_usecs = pdata->settle_delay_usecs;
1045
1046                 x++;
1047                 x->tx_buf = &packet->read_x;
1048                 x->len = 1;
1049                 spi_message_add_tail(x, m);
1050
1051                 x++;
1052                 x->rx_buf = &packet->tc.x;
1053                 x->len = 2;
1054                 spi_message_add_tail(x, m);
1055         }
1056
1057         m->complete = ads7846_rx_val;
1058         m->context = ts;
1059
1060         /* turn y+ off, x- on; we'll use formula #2 */
1061         if (ts->model == 7846) {
1062                 m++;
1063                 spi_message_init(m);
1064
1065                 x++;
1066                 packet->read_z1 = READ_Z1(vref);
1067                 x->tx_buf = &packet->read_z1;
1068                 x->len = 1;
1069                 spi_message_add_tail(x, m);
1070
1071                 x++;
1072                 x->rx_buf = &packet->tc.z1;
1073                 x->len = 2;
1074                 spi_message_add_tail(x, m);
1075
1076                 /* ... maybe discard first sample ... */
1077                 if (pdata->settle_delay_usecs) {
1078                         x->delay_usecs = pdata->settle_delay_usecs;
1079
1080                         x++;
1081                         x->tx_buf = &packet->read_z1;
1082                         x->len = 1;
1083                         spi_message_add_tail(x, m);
1084
1085                         x++;
1086                         x->rx_buf = &packet->tc.z1;
1087                         x->len = 2;
1088                         spi_message_add_tail(x, m);
1089                 }
1090
1091                 m->complete = ads7846_rx_val;
1092                 m->context = ts;
1093
1094                 m++;
1095                 spi_message_init(m);
1096
1097                 x++;
1098                 packet->read_z2 = READ_Z2(vref);
1099                 x->tx_buf = &packet->read_z2;
1100                 x->len = 1;
1101                 spi_message_add_tail(x, m);
1102
1103                 x++;
1104                 x->rx_buf = &packet->tc.z2;
1105                 x->len = 2;
1106                 spi_message_add_tail(x, m);
1107
1108                 /* ... maybe discard first sample ... */
1109                 if (pdata->settle_delay_usecs) {
1110                         x->delay_usecs = pdata->settle_delay_usecs;
1111
1112                         x++;
1113                         x->tx_buf = &packet->read_z2;
1114                         x->len = 1;
1115                         spi_message_add_tail(x, m);
1116
1117                         x++;
1118                         x->rx_buf = &packet->tc.z2;
1119                         x->len = 2;
1120                         spi_message_add_tail(x, m);
1121                 }
1122
1123                 m->complete = ads7846_rx_val;
1124                 m->context = ts;
1125         }
1126
1127         /* power down */
1128         m++;
1129         spi_message_init(m);
1130
1131         x++;
1132         packet->pwrdown = PWRDOWN;
1133         x->tx_buf = &packet->pwrdown;
1134         x->len = 1;
1135         spi_message_add_tail(x, m);
1136
1137         x++;
1138         x->rx_buf = &packet->dummy;
1139         x->len = 2;
1140         CS_CHANGE(*x);
1141         spi_message_add_tail(x, m);
1142
1143         m->complete = ads7846_rx;
1144         m->context = ts;
1145
1146         ts->last_msg = m;
1147
1148         ts->reg = regulator_get(&spi->dev, "vcc");
1149         if (IS_ERR(ts->reg)) {
1150                 dev_err(&spi->dev, "unable to get regulator: %ld\n",
1151                         PTR_ERR(ts->reg));
1152                 goto err_free_gpio;
1153         }
1154
1155         err = regulator_enable(ts->reg);
1156         if (err) {
1157                 dev_err(&spi->dev, "unable to enable regulator: %d\n", err);
1158                 goto err_put_regulator;
1159         }
1160
1161         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1162                         spi->dev.driver->name, ts)) {
1163                 dev_info(&spi->dev,
1164                         "trying pin change workaround on irq %d\n", spi->irq);
1165                 err = request_irq(spi->irq, ads7846_irq,
1166                                   IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
1167                                   spi->dev.driver->name, ts);
1168                 if (err) {
1169                         dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1170                         goto err_disable_regulator;
1171                 }
1172         }
1173
1174         err = ads784x_hwmon_register(spi, ts);
1175         if (err)
1176                 goto err_free_irq;
1177
1178         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1179
1180         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1181          * the touchscreen, in case it's not connected.
1182          */
1183         (void) ads7846_read12_ser(&spi->dev,
1184                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1185
1186         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1187         if (err)
1188                 goto err_remove_hwmon;
1189
1190         err = input_register_device(input_dev);
1191         if (err)
1192                 goto err_remove_attr_group;
1193
1194         return 0;
1195
1196  err_remove_attr_group:
1197         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1198  err_remove_hwmon:
1199         ads784x_hwmon_unregister(spi, ts);
1200  err_free_irq:
1201         free_irq(spi->irq, ts);
1202  err_disable_regulator:
1203         regulator_disable(ts->reg);
1204  err_put_regulator:
1205         regulator_put(ts->reg);
1206  err_free_gpio:
1207         if (ts->gpio_pendown != -1)
1208                 gpio_free(ts->gpio_pendown);
1209  err_cleanup_filter:
1210         if (ts->filter_cleanup)
1211                 ts->filter_cleanup(ts->filter_data);
1212  err_free_mem:
1213         input_free_device(input_dev);
1214         kfree(packet);
1215         kfree(ts);
1216         return err;
1217 }
1218
1219 static int __devexit ads7846_remove(struct spi_device *spi)
1220 {
1221         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1222
1223         ads784x_hwmon_unregister(spi, ts);
1224         input_unregister_device(ts->input);
1225
1226         ads7846_suspend(spi, PMSG_SUSPEND);
1227
1228         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1229
1230         free_irq(ts->spi->irq, ts);
1231         /* suspend left the IRQ disabled */
1232         enable_irq(ts->spi->irq);
1233
1234         regulator_disable(ts->reg);
1235         regulator_put(ts->reg);
1236
1237         if (ts->gpio_pendown != -1)
1238                 gpio_free(ts->gpio_pendown);
1239
1240         if (ts->filter_cleanup)
1241                 ts->filter_cleanup(ts->filter_data);
1242
1243         kfree(ts->packet);
1244         kfree(ts);
1245
1246         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1247         return 0;
1248 }
1249
1250 static struct spi_driver ads7846_driver = {
1251         .driver = {
1252                 .name   = "ads7846",
1253                 .bus    = &spi_bus_type,
1254                 .owner  = THIS_MODULE,
1255         },
1256         .probe          = ads7846_probe,
1257         .remove         = __devexit_p(ads7846_remove),
1258         .suspend        = ads7846_suspend,
1259         .resume         = ads7846_resume,
1260 };
1261
1262 static int __init ads7846_init(void)
1263 {
1264         return spi_register_driver(&ads7846_driver);
1265 }
1266 module_init(ads7846_init);
1267
1268 static void __exit ads7846_exit(void)
1269 {
1270         spi_unregister_driver(&ads7846_driver);
1271 }
1272 module_exit(ads7846_exit);
1273
1274 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1275 MODULE_LICENSE("GPL");
1276 MODULE_ALIAS("spi:ads7846");