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  * TSC2046 is just newer ads7846 silicon.
  43  * Support for ads7843 tested on Atmel at91sam926x-EK.
  44  * Support for ads7845 has only been stubbed in.
  45  *
  46  * IRQ handling needs a workaround because of a shortcoming in handling
  47  * edge triggered IRQs on some platforms like the OMAP1/2. These
  48  * platforms don't handle the ARM lazy IRQ disabling properly, thus we
  49  * have to maintain our own SW IRQ disabled status. This should be
  50  * removed as soon as the affected platform's IRQ handling is fixed.
  51  *
  52  * app note sbaa036 talks in more detail about accurate sampling...
  53  * that ought to help in situations like LCDs inducing noise (which
  54  * can also be helped by using synch signals) and more generally.
  55  * This driver tries to utilize the measures described in the app
  56  * note. The strength of filtering can be set in the board-* specific
  57  * files.
  58  */
  59
  60 #define TS_POLL_DELAY   (1 * 1000000)   /* ns delay before the first sample */
  61 #define TS_POLL_PERIOD  (5 * 1000000)   /* ns delay between samples */
  62
  63 /* this driver doesn't aim at the peak continuous sample rate */
  64 #define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  65
  66 struct ts_event {
  67         /* For portability, we can't read 12 bit values using SPI (which
  68          * would make the controller deliver them as native byteorder u16
  69          * with msbs zeroed).  Instead, we read them as two 8-bit values,
  70          * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  71          */
  72         u16     x;
  73         u16     y;
  74         u16     z1, z2;
  75         int     ignore;
  76 };
  77
  78 struct ads7846 {
  79         struct input_dev        *input;
  80         char                    phys[32];
  81
  82         struct spi_device       *spi;
  83
  84 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
  85         struct attribute_group  *attr_group;
  86         struct device           *hwmon;
  87 #endif
  88
  89         u16                     model;
  90         u16                     vref_delay_usecs;
  91         u16                     x_plate_ohms;
  92         u16                     pressure_max;
  93
  94         u8                      read_x, read_y, read_z1, read_z2, pwrdown;
  95         u16                     dummy;          /* for the pwrdown read */
  96         struct ts_event         tc;
  97
  98         struct spi_transfer     xfer[18];
  99         struct spi_message      msg[5];
 100         struct spi_message      *last_msg;
 101         int                     msg_idx;
 102         int                     read_cnt;
 103         int                     read_rep;
 104         int                     last_read;
 105
 106         u16                     debounce_max;
 107         u16                     debounce_tol;
 108         u16                     debounce_rep;
 109
 110         u16                     penirq_recheck_delay_usecs;
 111
 112         spinlock_t              lock;
 113         struct hrtimer          timer;
 114         unsigned                pendown:1;      /* P: lock */
 115         unsigned                pending:1;      /* P: lock */
 116 // FIXME remove "irq_disabled"
 117         unsigned                irq_disabled:1; /* P: lock */
 118         unsigned                disabled:1;
 119         unsigned                is_suspended:1;
 120
 121         int                     (*filter)(void *data, int data_idx, int *val);
 122         void                    *filter_data;
 123         void                    (*filter_cleanup)(void *data);
 124         int                     (*get_pendown_state)(void);
 125 };
 126
 127 /* leave chip selected when we're done, for quicker re-select? */
 128 #if     0
 129 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
 130 #else
 131 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
 132 #endif
 133
 134 /*--------------------------------------------------------------------------*/
 135
 136 /* The ADS7846 has touchscreen and other sensors.
 137  * Earlier ads784x chips are somewhat compatible.
 138  */
 139 #define ADS_START               (1 << 7)
 140 #define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
 141 #define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
 142 #define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
 143 #define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
 144 #define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
 145 #define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
 146 #define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
 147 #define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
 148 #define ADS_8_BIT               (1 << 3)
 149 #define ADS_12_BIT              (0 << 3)
 150 #define ADS_SER                 (1 << 2)        /* non-differential */
 151 #define ADS_DFR                 (0 << 2)        /* differential */
 152 #define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
 153 #define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
 154 #define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
 155 #define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
 156
 157 #define MAX_12BIT       ((1<<12)-1)
 158
 159 /* leave ADC powered up (disables penirq) between differential samples */
 160 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
 161         | ADS_12_BIT | ADS_DFR | \
 162         (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
 163
 164 #define READ_Y(vref)    (READ_12BIT_DFR(y,  1, vref))
 165 #define READ_Z1(vref)   (READ_12BIT_DFR(z1, 1, vref))
 166 #define READ_Z2(vref)   (READ_12BIT_DFR(z2, 1, vref))
 167
 168 #define READ_X(vref)    (READ_12BIT_DFR(x,  1, vref))
 169 #define PWRDOWN         (READ_12BIT_DFR(y,  0, 0))      /* LAST */
 170
 171 /* single-ended samples need to first power up reference voltage;
 172  * we leave both ADC and VREF powered
 173  */
 174 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
 175         | ADS_12_BIT | ADS_SER)
 176
 177 #define REF_ON  (READ_12BIT_DFR(x, 1, 1))
 178 #define REF_OFF (READ_12BIT_DFR(y, 0, 0))
 179
 180 /*--------------------------------------------------------------------------*/
 181
 182 /*
 183  * Non-touchscreen sensors only use single-ended conversions.
 184  * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
 185  * ads7846 lets that pin be unconnected, to use internal vREF.
 186  */
 187 static unsigned vREF_mV;
 188 module_param(vREF_mV, uint, 0);
 189 MODULE_PARM_DESC(vREF_mV, "external vREF voltage, in milliVolts");
 190
 191 struct ser_req {
 192         u8                      ref_on;
 193         u8                      command;
 194         u8                      ref_off;
 195         u16                     scratch;
 196         __be16                  sample;
 197         struct spi_message      msg;
 198         struct spi_transfer     xfer[6];
 199 };
 200
 201 static void ads7846_enable(struct ads7846 *ts);
 202 static void ads7846_disable(struct ads7846 *ts);
 203
 204 static int device_suspended(struct device *dev)
 205 {
 206         struct ads7846 *ts = dev_get_drvdata(dev);
 207         return ts->is_suspended || ts->disabled;
 208 }
 209
 210 static int ads7846_read12_ser(struct device *dev, unsigned command)
 211 {
 212         struct spi_device       *spi = to_spi_device(dev);
 213         struct ads7846          *ts = dev_get_drvdata(dev);
 214         struct ser_req          *req = kzalloc(sizeof *req, GFP_KERNEL);
 215         int                     status;
 216         int                     sample;
 217         int                     use_internal;
 218
 219         if (!req)
 220                 return -ENOMEM;
 221
 222         spi_message_init(&req->msg);
 223
 224         /* FIXME boards with ads7846 might use external vref instead ... */
 225         use_internal = (ts->model == 7846);
 226
 227         /* maybe turn on internal vREF, and let it settle */
 228         if (use_internal) {
 229                 req->ref_on = REF_ON;
 230                 req->xfer[0].tx_buf = &req->ref_on;
 231                 req->xfer[0].len = 1;
 232                 spi_message_add_tail(&req->xfer[0], &req->msg);
 233
 234                 req->xfer[1].rx_buf = &req->scratch;
 235                 req->xfer[1].len = 2;
 236
 237                 /* for 1uF, settle for 800 usec; no cap, 100 usec.  */
 238                 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
 239                 spi_message_add_tail(&req->xfer[1], &req->msg);
 240         }
 241
 242         /* take sample */
 243         req->command = (u8) command;
 244         req->xfer[2].tx_buf = &req->command;
 245         req->xfer[2].len = 1;
 246         spi_message_add_tail(&req->xfer[2], &req->msg);
 247
 248         req->xfer[3].rx_buf = &req->sample;
 249         req->xfer[3].len = 2;
 250         spi_message_add_tail(&req->xfer[3], &req->msg);
 251
 252         /* REVISIT:  take a few more samples, and compare ... */
 253
 254         /* converter in low power mode & enable PENIRQ */
 255         req->ref_off = PWRDOWN;
 256         req->xfer[4].tx_buf = &req->ref_off;
 257         req->xfer[4].len = 1;
 258         spi_message_add_tail(&req->xfer[4], &req->msg);
 259
 260         req->xfer[5].rx_buf = &req->scratch;
 261         req->xfer[5].len = 2;
 262         CS_CHANGE(req->xfer[5]);
 263         spi_message_add_tail(&req->xfer[5], &req->msg);
 264
 265         ts->irq_disabled = 1;
 266         disable_irq(spi->irq);
 267         status = spi_sync(spi, &req->msg);
 268         ts->irq_disabled = 0;
 269         enable_irq(spi->irq);
 270
 271         if (status == 0) {
 272                 /* on-wire is a must-ignore bit, a BE12 value, then padding */
 273                 sample = be16_to_cpu(req->sample);
 274                 sample = sample >> 3;
 275                 sample &= 0x0fff;
 276         }
 277
 278         kfree(req);
 279         return status ? status : sample;
 280 }
 281
 282 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 283
 284 #define SHOW(name, var, adjust) static ssize_t \
 285 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 286 { \
 287         struct ads7846 *ts = dev_get_drvdata(dev); \
 288         ssize_t v = ads7846_read12_ser(dev, \
 289                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 290         if (v < 0) \
 291                 return v; \
 292         return sprintf(buf, "%u\n", adjust(ts, v)); \
 293 } \
 294 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 295
 296
 297 /* Sysfs conventions report temperatures in millidegrees Celcius.
 298  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 299  * accuracy scheme without calibration data.  For now we won't try either;
 300  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 301  */
 302 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 303 {
 304         return v;
 305 }
 306
 307 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 308 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 309
 310
 311 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 312  * if we know vREF.  userspace may need to scale vAUX to match the board's
 313  * external resistors; we assume that vBATT only uses the internal ones.
 314  */
 315 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 316 {
 317         unsigned retval = v;
 318
 319         /* external resistors may scale vAUX into 0..vREF */
 320         retval *= vREF_mV;
 321         retval = retval >> 12;
 322         return retval;
 323 }
 324
 325 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 326 {
 327         unsigned retval = vaux_adjust(ts, v);
 328
 329         /* ads7846 has a resistor ladder to scale this signal down */
 330         if (ts->model == 7846)
 331                 retval *= 4;
 332         return retval;
 333 }
 334
 335 SHOW(in0_input, vaux, vaux_adjust)
 336 SHOW(in1_input, vbatt, vbatt_adjust)
 337
 338
 339 static struct attribute *ads7846_attributes[] = {
 340         &dev_attr_temp0.attr,
 341         &dev_attr_temp1.attr,
 342         &dev_attr_in0_input.attr,
 343         &dev_attr_in1_input.attr,
 344         NULL,
 345 };
 346
 347 static struct attribute_group ads7846_attr_group = {
 348         .attrs = ads7846_attributes,
 349 };
 350
 351 static struct attribute *ads7843_attributes[] = {
 352         &dev_attr_in0_input.attr,
 353         &dev_attr_in1_input.attr,
 354         NULL,
 355 };
 356
 357 static struct attribute_group ads7843_attr_group = {
 358         .attrs = ads7843_attributes,
 359 };
 360
 361 static struct attribute *ads7845_attributes[] = {
 362         &dev_attr_in0_input.attr,
 363         NULL,
 364 };
 365
 366 static struct attribute_group ads7845_attr_group = {
 367         .attrs = ads7845_attributes,
 368 };
 369
 370 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 371 {
 372         struct device *hwmon;
 373         int err;
 374
 375         /* hwmon sensors need a reference voltage */
 376         switch (ts->model) {
 377         case 7846:
 378                 if (!vREF_mV) {
 379                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 380                         vREF_mV = 2500;
 381                 }
 382                 break;
 383         case 7845:
 384         case 7843:
 385                 if (!vREF_mV) {
 386                         dev_warn(&spi->dev,
 387                                 "external vREF for ADS%d not specified\n",
 388                                 ts->model);
 389                         return 0;
 390                 }
 391                 break;
 392         }
 393
 394         /* different chips have different sensor groups */
 395         switch (ts->model) {
 396         case 7846:
 397                 ts->attr_group = &ads7846_attr_group;
 398                 break;
 399         case 7845:
 400                 ts->attr_group = &ads7845_attr_group;
 401                 break;
 402         case 7843:
 403                 ts->attr_group = &ads7843_attr_group;
 404                 break;
 405         default:
 406                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 407                 return 0;
 408         }
 409
 410         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 411         if (err)
 412                 return err;
 413
 414         hwmon = hwmon_device_register(&spi->dev);
 415         if (IS_ERR(hwmon)) {
 416                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 417                 return PTR_ERR(hwmon);
 418         }
 419
 420         ts->hwmon = hwmon;
 421         return 0;
 422 }
 423
 424 static void ads784x_hwmon_unregister(struct spi_device *spi,
 425                                      struct ads7846 *ts)
 426 {
 427         if (ts->hwmon) {
 428                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 429                 hwmon_device_unregister(ts->hwmon);
 430         }
 431 }
 432
 433 #else
 434 static inline int ads784x_hwmon_register(struct spi_device *spi,
 435                                          struct ads7846 *ts)
 436 {
 437         return 0;
 438 }
 439
 440 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 441                                             struct ads7846 *ts)
 442 {
 443 }
 444 #endif
 445
 446 static int is_pen_down(struct device *dev)
 447 {
 448         struct ads7846  *ts = dev_get_drvdata(dev);
 449
 450         return ts->pendown;
 451 }
 452
 453 static ssize_t ads7846_pen_down_show(struct device *dev,
 454                                      struct device_attribute *attr, char *buf)
 455 {
 456         return sprintf(buf, "%u\n", is_pen_down(dev));
 457 }
 458
 459 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 460
 461 static ssize_t ads7846_disable_show(struct device *dev,
 462                                      struct device_attribute *attr, char *buf)
 463 {
 464         struct ads7846  *ts = dev_get_drvdata(dev);
 465
 466         return sprintf(buf, "%u\n", ts->disabled);
 467 }
 468
 469 static ssize_t ads7846_disable_store(struct device *dev,
 470                                      struct device_attribute *attr,
 471                                      const char *buf, size_t count)
 472 {
 473         struct ads7846 *ts = dev_get_drvdata(dev);
 474         char *endp;
 475         int i;
 476
 477         i = simple_strtoul(buf, &endp, 10);
 478         spin_lock_irq(&ts->lock);
 479
 480         if (i)
 481                 ads7846_disable(ts);
 482         else
 483                 ads7846_enable(ts);
 484
 485         spin_unlock_irq(&ts->lock);
 486
 487         return count;
 488 }
 489
 490 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 491
 492 static struct attribute *ads784x_attributes[] = {
 493         &dev_attr_pen_down.attr,
 494         &dev_attr_disable.attr,
 495         NULL,
 496 };
 497
 498 static struct attribute_group ads784x_attr_group = {
 499         .attrs = ads784x_attributes,
 500 };
 501
 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 (likely(x && z1)) {
 531                 /* compute touch pressure resistance using equation #2 */
 532                 Rt = z2;
 533                 Rt -= z1;
 534                 Rt *= x;
 535                 Rt *= ts->x_plate_ohms;
 536                 Rt /= z1;
 537                 Rt = (Rt + 2047) >> 12;
 538         } else
 539                 Rt = 0;
 540
 541         if (ts->model == 7843)
 542                 Rt = ts->pressure_max / 2;
 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 (!ts->get_pendown_state())
 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         u16 *rx_val;
 647         int val;
 648         int action;
 649         int status;
 650
 651         m = &ts->msg[ts->msg_idx];
 652         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 653         rx_val = t->rx_buf;
 654
 655         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 656          * built from two 8 bit values written msb-first.
 657          */
 658         val = be16_to_cpu(*rx_val) >> 3;
 659
 660         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 661         switch (action) {
 662         case ADS7846_FILTER_REPEAT:
 663                 break;
 664         case ADS7846_FILTER_IGNORE:
 665                 ts->tc.ignore = 1;
 666                 /* Last message will contain ads7846_rx() as the
 667                  * completion function.
 668                  */
 669                 m = ts->last_msg;
 670                 break;
 671         case ADS7846_FILTER_OK:
 672                 *rx_val = val;
 673                 ts->tc.ignore = 0;
 674                 m = &ts->msg[++ts->msg_idx];
 675                 break;
 676         default:
 677                 BUG();
 678         }
 679         status = spi_async(ts->spi, m);
 680         if (status)
 681                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 682                                 status);
 683 }
 684
 685 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 686 {
 687         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 688         int             status = 0;
 689
 690         spin_lock_irq(&ts->lock);
 691
 692         if (unlikely(!ts->get_pendown_state() ||
 693                      device_suspended(&ts->spi->dev))) {
 694                 if (ts->pendown) {
 695                         struct input_dev *input = ts->input;
 696
 697                         input_report_key(input, BTN_TOUCH, 0);
 698                         input_report_abs(input, ABS_PRESSURE, 0);
 699                         input_sync(input);
 700
 701                         ts->pendown = 0;
 702 #ifdef VERBOSE
 703                         dev_dbg(&ts->spi->dev, "UP\n");
 704 #endif
 705                 }
 706
 707                 /* measurement cycle ended */
 708                 if (!device_suspended(&ts->spi->dev)) {
 709                         ts->irq_disabled = 0;
 710                         enable_irq(ts->spi->irq);
 711                 }
 712                 ts->pending = 0;
 713         } else {
 714                 /* pen is still down, continue with the measurement */
 715                 ts->msg_idx = 0;
 716                 status = spi_async(ts->spi, &ts->msg[0]);
 717                 if (status)
 718                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 719         }
 720
 721         spin_unlock_irq(&ts->lock);
 722         return HRTIMER_NORESTART;
 723 }
 724
 725 static irqreturn_t ads7846_irq(int irq, void *handle)
 726 {
 727         struct ads7846 *ts = handle;
 728         unsigned long flags;
 729
 730         spin_lock_irqsave(&ts->lock, flags);
 731         if (likely(ts->get_pendown_state())) {
 732                 if (!ts->irq_disabled) {
 733                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 734                          * like the other dispatchers:  it will report IRQs
 735                          * even after they've been disabled.  We work around
 736                          * that here.  (The "generic irq" framework may help...)
 737                          */
 738                         ts->irq_disabled = 1;
 739                         disable_irq(ts->spi->irq);
 740                         ts->pending = 1;
 741                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 742                                         HRTIMER_MODE_REL);
 743                 }
 744         }
 745         spin_unlock_irqrestore(&ts->lock, flags);
 746
 747         return IRQ_HANDLED;
 748 }
 749
 750 /*--------------------------------------------------------------------------*/
 751
 752 /* Must be called with ts->lock held */
 753 static void ads7846_disable(struct ads7846 *ts)
 754 {
 755         if (ts->disabled)
 756                 return;
 757
 758         ts->disabled = 1;
 759
 760         /* are we waiting for IRQ, or polling? */
 761         if (!ts->pending) {
 762                 ts->irq_disabled = 1;
 763                 disable_irq(ts->spi->irq);
 764         } else {
 765                 /* the timer will run at least once more, and
 766                  * leave everything in a clean state, IRQ disabled
 767                  */
 768                 while (ts->pending) {
 769                         spin_unlock_irq(&ts->lock);
 770                         msleep(1);
 771                         spin_lock_irq(&ts->lock);
 772                 }
 773         }
 774
 775         /* we know the chip's in lowpower mode since we always
 776          * leave it that way after every request
 777          */
 778
 779 }
 780
 781 /* Must be called with ts->lock held */
 782 static void ads7846_enable(struct ads7846 *ts)
 783 {
 784         if (!ts->disabled)
 785                 return;
 786
 787         ts->disabled = 0;
 788         ts->irq_disabled = 0;
 789         enable_irq(ts->spi->irq);
 790 }
 791
 792 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 793 {
 794         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 795
 796         spin_lock_irq(&ts->lock);
 797
 798         ts->is_suspended = 1;
 799         ads7846_disable(ts);
 800
 801         spin_unlock_irq(&ts->lock);
 802
 803         return 0;
 804
 805 }
 806
 807 static int ads7846_resume(struct spi_device *spi)
 808 {
 809         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 810
 811         spin_lock_irq(&ts->lock);
 812
 813         ts->is_suspended = 0;
 814         ads7846_enable(ts);
 815
 816         spin_unlock_irq(&ts->lock);
 817
 818         return 0;
 819 }
 820
 821 static int __devinit ads7846_probe(struct spi_device *spi)
 822 {
 823         struct ads7846                  *ts;
 824         struct input_dev                *input_dev;
 825         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 826         struct spi_message              *m;
 827         struct spi_transfer             *x;
 828         int                             vref;
 829         int                             err;
 830
 831         if (!spi->irq) {
 832                 dev_dbg(&spi->dev, "no IRQ?\n");
 833                 return -ENODEV;
 834         }
 835
 836         if (!pdata) {
 837                 dev_dbg(&spi->dev, "no platform data?\n");
 838                 return -ENODEV;
 839         }
 840
 841         /* don't exceed max specified sample rate */
 842         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 843                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 844                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 845                 return -EINVAL;
 846         }
 847
 848         /* REVISIT when the irq can be triggered active-low, or if for some
 849          * reason the touchscreen isn't hooked up, we don't need to access
 850          * the pendown state.
 851          */
 852         if (pdata->get_pendown_state == NULL) {
 853                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 854                 return -EINVAL;
 855         }
 856
 857         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 858          * that even if the hardware can do that, the SPI controller driver
 859          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 860          */
 861         spi->bits_per_word = 8;
 862         spi->mode = SPI_MODE_0;
 863         err = spi_setup(spi);
 864         if (err < 0)
 865                 return err;
 866
 867         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 868         input_dev = input_allocate_device();
 869         if (!ts || !input_dev) {
 870                 err = -ENOMEM;
 871                 goto err_free_mem;
 872         }
 873
 874         dev_set_drvdata(&spi->dev, ts);
 875
 876         ts->spi = spi;
 877         ts->input = input_dev;
 878
 879         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 880         ts->timer.function = ads7846_timer;
 881
 882         spin_lock_init(&ts->lock);
 883
 884         ts->model = pdata->model ? : 7846;
 885         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 886         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 887         ts->pressure_max = pdata->pressure_max ? : ~0;
 888
 889         if (pdata->filter != NULL) {
 890                 if (pdata->filter_init != NULL) {
 891                         err = pdata->filter_init(pdata, &ts->filter_data);
 892                         if (err < 0)
 893                                 goto err_free_mem;
 894                 }
 895                 ts->filter = pdata->filter;
 896                 ts->filter_cleanup = pdata->filter_cleanup;
 897         } else if (pdata->debounce_max) {
 898                 ts->debounce_max = pdata->debounce_max;
 899                 if (ts->debounce_max < 2)
 900                         ts->debounce_max = 2;
 901                 ts->debounce_tol = pdata->debounce_tol;
 902                 ts->debounce_rep = pdata->debounce_rep;
 903                 ts->filter = ads7846_debounce;
 904                 ts->filter_data = ts;
 905         } else
 906                 ts->filter = ads7846_no_filter;
 907         ts->get_pendown_state = pdata->get_pendown_state;
 908
 909         if (pdata->penirq_recheck_delay_usecs)
 910                 ts->penirq_recheck_delay_usecs =
 911                                 pdata->penirq_recheck_delay_usecs;
 912
 913         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 914
 915         input_dev->name = "ADS784x Touchscreen";
 916         input_dev->phys = ts->phys;
 917         input_dev->dev.parent = &spi->dev;
 918
 919         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 920         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 921         input_set_abs_params(input_dev, ABS_X,
 922                         pdata->x_min ? : 0,
 923                         pdata->x_max ? : MAX_12BIT,
 924                         0, 0);
 925         input_set_abs_params(input_dev, ABS_Y,
 926                         pdata->y_min ? : 0,
 927                         pdata->y_max ? : MAX_12BIT,
 928                         0, 0);
 929         input_set_abs_params(input_dev, ABS_PRESSURE,
 930                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 931
 932         vref = pdata->keep_vref_on;
 933
 934         /* set up the transfers to read touchscreen state; this assumes we
 935          * use formula #2 for pressure, not #3.
 936          */
 937         m = &ts->msg[0];
 938         x = ts->xfer;
 939
 940         spi_message_init(m);
 941
 942         /* y- still on; turn on only y+ (and ADC) */
 943         ts->read_y = READ_Y(vref);
 944         x->tx_buf = &ts->read_y;
 945         x->len = 1;
 946         spi_message_add_tail(x, m);
 947
 948         x++;
 949         x->rx_buf = &ts->tc.y;
 950         x->len = 2;
 951         spi_message_add_tail(x, m);
 952
 953         /* the first sample after switching drivers can be low quality;
 954          * optionally discard it, using a second one after the signals
 955          * have had enough time to stabilize.
 956          */
 957         if (pdata->settle_delay_usecs) {
 958                 x->delay_usecs = pdata->settle_delay_usecs;
 959
 960                 x++;
 961                 x->tx_buf = &ts->read_y;
 962                 x->len = 1;
 963                 spi_message_add_tail(x, m);
 964
 965                 x++;
 966                 x->rx_buf = &ts->tc.y;
 967                 x->len = 2;
 968                 spi_message_add_tail(x, m);
 969         }
 970
 971         m->complete = ads7846_rx_val;
 972         m->context = ts;
 973
 974         m++;
 975         spi_message_init(m);
 976
 977         /* turn y- off, x+ on, then leave in lowpower */
 978         x++;
 979         ts->read_x = READ_X(vref);
 980         x->tx_buf = &ts->read_x;
 981         x->len = 1;
 982         spi_message_add_tail(x, m);
 983
 984         x++;
 985         x->rx_buf = &ts->tc.x;
 986         x->len = 2;
 987         spi_message_add_tail(x, m);
 988
 989         /* ... maybe discard first sample ... */
 990         if (pdata->settle_delay_usecs) {
 991                 x->delay_usecs = pdata->settle_delay_usecs;
 992
 993                 x++;
 994                 x->tx_buf = &ts->read_x;
 995                 x->len = 1;
 996                 spi_message_add_tail(x, m);
 997
 998                 x++;
 999                 x->rx_buf = &ts->tc.x;
1000                 x->len = 2;
1001                 spi_message_add_tail(x, m);
1002         }
1003
1004         m->complete = ads7846_rx_val;
1005         m->context = ts;
1006
1007         /* turn y+ off, x- on; we'll use formula #2 */
1008         if (ts->model == 7846) {
1009                 m++;
1010                 spi_message_init(m);
1011
1012                 x++;
1013                 ts->read_z1 = READ_Z1(vref);
1014                 x->tx_buf = &ts->read_z1;
1015                 x->len = 1;
1016                 spi_message_add_tail(x, m);
1017
1018                 x++;
1019                 x->rx_buf = &ts->tc.z1;
1020                 x->len = 2;
1021                 spi_message_add_tail(x, m);
1022
1023                 /* ... maybe discard first sample ... */
1024                 if (pdata->settle_delay_usecs) {
1025                         x->delay_usecs = pdata->settle_delay_usecs;
1026
1027                         x++;
1028                         x->tx_buf = &ts->read_z1;
1029                         x->len = 1;
1030                         spi_message_add_tail(x, m);
1031
1032                         x++;
1033                         x->rx_buf = &ts->tc.z1;
1034                         x->len = 2;
1035                         spi_message_add_tail(x, m);
1036                 }
1037
1038                 m->complete = ads7846_rx_val;
1039                 m->context = ts;
1040
1041                 m++;
1042                 spi_message_init(m);
1043
1044                 x++;
1045                 ts->read_z2 = READ_Z2(vref);
1046                 x->tx_buf = &ts->read_z2;
1047                 x->len = 1;
1048                 spi_message_add_tail(x, m);
1049
1050                 x++;
1051                 x->rx_buf = &ts->tc.z2;
1052                 x->len = 2;
1053                 spi_message_add_tail(x, m);
1054
1055                 /* ... maybe discard first sample ... */
1056                 if (pdata->settle_delay_usecs) {
1057                         x->delay_usecs = pdata->settle_delay_usecs;
1058
1059                         x++;
1060                         x->tx_buf = &ts->read_z2;
1061                         x->len = 1;
1062                         spi_message_add_tail(x, m);
1063
1064                         x++;
1065                         x->rx_buf = &ts->tc.z2;
1066                         x->len = 2;
1067                         spi_message_add_tail(x, m);
1068                 }
1069
1070                 m->complete = ads7846_rx_val;
1071                 m->context = ts;
1072         }
1073
1074         /* power down */
1075         m++;
1076         spi_message_init(m);
1077
1078         x++;
1079         ts->pwrdown = PWRDOWN;
1080         x->tx_buf = &ts->pwrdown;
1081         x->len = 1;
1082         spi_message_add_tail(x, m);
1083
1084         x++;
1085         x->rx_buf = &ts->dummy;
1086         x->len = 2;
1087         CS_CHANGE(*x);
1088         spi_message_add_tail(x, m);
1089
1090         m->complete = ads7846_rx;
1091         m->context = ts;
1092
1093         ts->last_msg = m;
1094
1095         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1096                         spi->dev.driver->name, ts)) {
1097                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1098                 err = -EBUSY;
1099                 goto err_cleanup_filter;
1100         }
1101
1102         err = ads784x_hwmon_register(spi, ts);
1103         if (err)
1104                 goto err_free_irq;
1105
1106         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1107
1108         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1109          * the touchscreen, in case it's not connected.
1110          */
1111         (void) ads7846_read12_ser(&spi->dev,
1112                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1113
1114         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1115         if (err)
1116                 goto err_remove_hwmon;
1117
1118         err = input_register_device(input_dev);
1119         if (err)
1120                 goto err_remove_attr_group;
1121
1122         return 0;
1123
1124  err_remove_attr_group:
1125         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1126  err_remove_hwmon:
1127         ads784x_hwmon_unregister(spi, ts);
1128  err_free_irq:
1129         free_irq(spi->irq, ts);
1130  err_cleanup_filter:
1131         if (ts->filter_cleanup)
1132                 ts->filter_cleanup(ts->filter_data);
1133  err_free_mem:
1134         input_free_device(input_dev);
1135         kfree(ts);
1136         return err;
1137 }
1138
1139 static int __devexit ads7846_remove(struct spi_device *spi)
1140 {
1141         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1142
1143         ads784x_hwmon_unregister(spi, ts);
1144         input_unregister_device(ts->input);
1145
1146         ads7846_suspend(spi, PMSG_SUSPEND);
1147
1148         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1149
1150         free_irq(ts->spi->irq, ts);
1151         /* suspend left the IRQ disabled */
1152         enable_irq(ts->spi->irq);
1153
1154         if (ts->filter_cleanup)
1155                 ts->filter_cleanup(ts->filter_data);
1156
1157         kfree(ts);
1158
1159         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1160         return 0;
1161 }
1162
1163 static struct spi_driver ads7846_driver = {
1164         .driver = {
1165                 .name   = "ads7846",
1166                 .bus    = &spi_bus_type,
1167                 .owner  = THIS_MODULE,
1168         },
1169         .probe          = ads7846_probe,
1170         .remove         = __devexit_p(ads7846_remove),
1171         .suspend        = ads7846_suspend,
1172         .resume         = ads7846_resume,
1173 };
1174
1175 static int __init ads7846_init(void)
1176 {
1177         /* grr, board-specific init should stay out of drivers!! */
1178
1179 #ifdef  CONFIG_ARCH_OMAP
1180         if (machine_is_omap_osk()) {
1181                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
1182                 omap_request_gpio(4);
1183                 omap_set_gpio_direction(4, 1);
1184                 omap_request_gpio(6);
1185                 omap_set_gpio_direction(6, 1);
1186         }
1187         // also TI 1510 Innovator, bitbanging through FPGA
1188         // also Nokia 770
1189         // also Palm Tungsten T2
1190 #endif
1191
1192         // PXA:
1193         // also Dell Axim X50
1194         // also HP iPaq H191x/H192x/H415x/H435x
1195         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
1196         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
1197
1198         // Atmel at91sam9261-EK uses ads7843
1199
1200         // also various AMD Au1x00 devel boards
1201
1202         return spi_register_driver(&ads7846_driver);
1203 }
1204 module_init(ads7846_init);
1205
1206 static void __exit ads7846_exit(void)
1207 {
1208         spi_unregister_driver(&ads7846_driver);
1209
1210 #ifdef  CONFIG_ARCH_OMAP
1211         if (machine_is_omap_osk()) {
1212                 omap_free_gpio(4);
1213                 omap_free_gpio(6);
1214         }
1215 #endif
1216
1217 }
1218 module_exit(ads7846_exit);
1219
1220 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1221 MODULE_LICENSE("GPL");