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 (req->msg.status)
 272                 status = req->msg.status;
 273
 274         /* on-wire is a must-ignore bit, a BE12 value, then padding */
 275         sample = be16_to_cpu(req->sample);
 276         sample = sample >> 3;
 277         sample &= 0x0fff;
 278
 279         kfree(req);
 280         return status ? status : sample;
 281 }
 282
 283 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
 284
 285 #define SHOW(name, var, adjust) static ssize_t \
 286 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 287 { \
 288         struct ads7846 *ts = dev_get_drvdata(dev); \
 289         ssize_t v = ads7846_read12_ser(dev, \
 290                         READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
 291         if (v < 0) \
 292                 return v; \
 293         return sprintf(buf, "%u\n", adjust(ts, v)); \
 294 } \
 295 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
 296
 297
 298 /* Sysfs conventions report temperatures in millidegrees Celcius.
 299  * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
 300  * accuracy scheme without calibration data.  For now we won't try either;
 301  * userspace sees raw sensor values, and must scale/calibrate appropriately.
 302  */
 303 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
 304 {
 305         return v;
 306 }
 307
 308 SHOW(temp0, temp0, null_adjust)         /* temp1_input */
 309 SHOW(temp1, temp1, null_adjust)         /* temp2_input */
 310
 311
 312 /* sysfs conventions report voltages in millivolts.  We can convert voltages
 313  * if we know vREF.  userspace may need to scale vAUX to match the board's
 314  * external resistors; we assume that vBATT only uses the internal ones.
 315  */
 316 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
 317 {
 318         unsigned retval = v;
 319
 320         /* external resistors may scale vAUX into 0..vREF */
 321         retval *= vREF_mV;
 322         retval = retval >> 12;
 323         return retval;
 324 }
 325
 326 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
 327 {
 328         unsigned retval = vaux_adjust(ts, v);
 329
 330         /* ads7846 has a resistor ladder to scale this signal down */
 331         if (ts->model == 7846)
 332                 retval *= 4;
 333         return retval;
 334 }
 335
 336 SHOW(in0_input, vaux, vaux_adjust)
 337 SHOW(in1_input, vbatt, vbatt_adjust)
 338
 339
 340 static struct attribute *ads7846_attributes[] = {
 341         &dev_attr_temp0.attr,
 342         &dev_attr_temp1.attr,
 343         &dev_attr_in0_input.attr,
 344         &dev_attr_in1_input.attr,
 345         NULL,
 346 };
 347
 348 static struct attribute_group ads7846_attr_group = {
 349         .attrs = ads7846_attributes,
 350 };
 351
 352 static struct attribute *ads7843_attributes[] = {
 353         &dev_attr_in0_input.attr,
 354         &dev_attr_in1_input.attr,
 355         NULL,
 356 };
 357
 358 static struct attribute_group ads7843_attr_group = {
 359         .attrs = ads7843_attributes,
 360 };
 361
 362 static struct attribute *ads7845_attributes[] = {
 363         &dev_attr_in0_input.attr,
 364         NULL,
 365 };
 366
 367 static struct attribute_group ads7845_attr_group = {
 368         .attrs = ads7845_attributes,
 369 };
 370
 371 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
 372 {
 373         struct device *hwmon;
 374         int err;
 375
 376         /* hwmon sensors need a reference voltage */
 377         switch (ts->model) {
 378         case 7846:
 379                 if (!vREF_mV) {
 380                         dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
 381                         vREF_mV = 2500;
 382                 }
 383                 break;
 384         case 7845:
 385         case 7843:
 386                 if (!vREF_mV) {
 387                         dev_warn(&spi->dev,
 388                                 "external vREF for ADS%d not specified\n",
 389                                 ts->model);
 390                         return 0;
 391                 }
 392                 break;
 393         }
 394
 395         /* different chips have different sensor groups */
 396         switch (ts->model) {
 397         case 7846:
 398                 ts->attr_group = &ads7846_attr_group;
 399                 break;
 400         case 7845:
 401                 ts->attr_group = &ads7845_attr_group;
 402                 break;
 403         case 7843:
 404                 ts->attr_group = &ads7843_attr_group;
 405                 break;
 406         default:
 407                 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
 408                 return 0;
 409         }
 410
 411         err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
 412         if (err)
 413                 return err;
 414
 415         hwmon = hwmon_device_register(&spi->dev);
 416         if (IS_ERR(hwmon)) {
 417                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 418                 return PTR_ERR(hwmon);
 419         }
 420
 421         ts->hwmon = hwmon;
 422         return 0;
 423 }
 424
 425 static void ads784x_hwmon_unregister(struct spi_device *spi,
 426                                      struct ads7846 *ts)
 427 {
 428         if (ts->hwmon) {
 429                 sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 430                 hwmon_device_unregister(ts->hwmon);
 431         }
 432 }
 433
 434 #else
 435 static inline int ads784x_hwmon_register(struct spi_device *spi,
 436                                          struct ads7846 *ts)
 437 {
 438         return 0;
 439 }
 440
 441 static inline void ads784x_hwmon_unregister(struct spi_device *spi,
 442                                             struct ads7846 *ts)
 443 {
 444 }
 445 #endif
 446
 447 static int is_pen_down(struct device *dev)
 448 {
 449         struct ads7846  *ts = dev_get_drvdata(dev);
 450
 451         return ts->pendown;
 452 }
 453
 454 static ssize_t ads7846_pen_down_show(struct device *dev,
 455                                      struct device_attribute *attr, char *buf)
 456 {
 457         return sprintf(buf, "%u\n", is_pen_down(dev));
 458 }
 459
 460 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
 461
 462 static ssize_t ads7846_disable_show(struct device *dev,
 463                                      struct device_attribute *attr, char *buf)
 464 {
 465         struct ads7846  *ts = dev_get_drvdata(dev);
 466
 467         return sprintf(buf, "%u\n", ts->disabled);
 468 }
 469
 470 static ssize_t ads7846_disable_store(struct device *dev,
 471                                      struct device_attribute *attr,
 472                                      const char *buf, size_t count)
 473 {
 474         struct ads7846 *ts = dev_get_drvdata(dev);
 475         char *endp;
 476         int i;
 477
 478         i = simple_strtoul(buf, &endp, 10);
 479         spin_lock_irq(&ts->lock);
 480
 481         if (i)
 482                 ads7846_disable(ts);
 483         else
 484                 ads7846_enable(ts);
 485
 486         spin_unlock_irq(&ts->lock);
 487
 488         return count;
 489 }
 490
 491 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 492
 493 static struct attribute *ads784x_attributes[] = {
 494         &dev_attr_pen_down.attr,
 495         &dev_attr_disable.attr,
 496         NULL,
 497 };
 498
 499 static struct attribute_group ads784x_attr_group = {
 500         .attrs = ads784x_attributes,
 501 };
 502
 503 /*--------------------------------------------------------------------------*/
 504
 505 /*
 506  * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 507  * to retrieve touchscreen status.
 508  *
 509  * The SPI transfer completion callback does the real work.  It reports
 510  * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 511  */
 512
 513 static void ads7846_rx(void *ads)
 514 {
 515         struct ads7846          *ts = ads;
 516         unsigned                Rt;
 517         u16                     x, y, z1, z2;
 518
 519         /* ads7846_rx_val() did in-place conversion (including byteswap) from
 520          * on-the-wire format as part of debouncing to get stable readings.
 521          */
 522         x = ts->tc.x;
 523         y = ts->tc.y;
 524         z1 = ts->tc.z1;
 525         z2 = ts->tc.z2;
 526
 527         /* range filtering */
 528         if (x == MAX_12BIT)
 529                 x = 0;
 530
 531         if (likely(x && z1)) {
 532                 /* compute touch pressure resistance using equation #2 */
 533                 Rt = z2;
 534                 Rt -= z1;
 535                 Rt *= x;
 536                 Rt *= ts->x_plate_ohms;
 537                 Rt /= z1;
 538                 Rt = (Rt + 2047) >> 12;
 539         } else
 540                 Rt = 0;
 541
 542         if (ts->model == 7843)
 543                 Rt = ts->pressure_max / 2;
 544
 545         /* Sample found inconsistent by debouncing or pressure is beyond
 546          * the maximum. Don't report it to user space, repeat at least
 547          * once more the measurement
 548          */
 549         if (ts->tc.ignore || Rt > ts->pressure_max) {
 550 #ifdef VERBOSE
 551                 pr_debug("%s: ignored %d pressure %d\n",
 552                         ts->spi->dev.bus_id, ts->tc.ignore, Rt);
 553 #endif
 554                 hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 555                               HRTIMER_MODE_REL);
 556                 return;
 557         }
 558
 559         /* Maybe check the pendown state before reporting. This discards
 560          * false readings when the pen is lifted.
 561          */
 562         if (ts->penirq_recheck_delay_usecs) {
 563                 udelay(ts->penirq_recheck_delay_usecs);
 564                 if (!ts->get_pendown_state())
 565                         Rt = 0;
 566         }
 567
 568         /* NOTE: We can't rely on the pressure to determine the pen down
 569          * state, even this controller has a pressure sensor.  The pressure
 570          * value can fluctuate for quite a while after lifting the pen and
 571          * in some cases may not even settle at the expected value.
 572          *
 573          * The only safe way to check for the pen up condition is in the
 574          * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
 575          */
 576         if (Rt) {
 577                 struct input_dev *input = ts->input;
 578
 579                 if (!ts->pendown) {
 580                         input_report_key(input, BTN_TOUCH, 1);
 581                         ts->pendown = 1;
 582 #ifdef VERBOSE
 583                         dev_dbg(&ts->spi->dev, "DOWN\n");
 584 #endif
 585                 }
 586                 input_report_abs(input, ABS_X, x);
 587                 input_report_abs(input, ABS_Y, y);
 588                 input_report_abs(input, ABS_PRESSURE, Rt);
 589
 590                 input_sync(input);
 591 #ifdef VERBOSE
 592                 dev_dbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
 593 #endif
 594         }
 595
 596         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
 597                         HRTIMER_MODE_REL);
 598 }
 599
 600 static int ads7846_debounce(void *ads, int data_idx, int *val)
 601 {
 602         struct ads7846          *ts = ads;
 603
 604         if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
 605                 /* Start over collecting consistent readings. */
 606                 ts->read_rep = 0;
 607                 /* Repeat it, if this was the first read or the read
 608                  * wasn't consistent enough. */
 609                 if (ts->read_cnt < ts->debounce_max) {
 610                         ts->last_read = *val;
 611                         ts->read_cnt++;
 612                         return ADS7846_FILTER_REPEAT;
 613                 } else {
 614                         /* Maximum number of debouncing reached and still
 615                          * not enough number of consistent readings. Abort
 616                          * the whole sample, repeat it in the next sampling
 617                          * period.
 618                          */
 619                         ts->read_cnt = 0;
 620                         return ADS7846_FILTER_IGNORE;
 621                 }
 622         } else {
 623                 if (++ts->read_rep > ts->debounce_rep) {
 624                         /* Got a good reading for this coordinate,
 625                          * go for the next one. */
 626                         ts->read_cnt = 0;
 627                         ts->read_rep = 0;
 628                         return ADS7846_FILTER_OK;
 629                 } else {
 630                         /* Read more values that are consistent. */
 631                         ts->read_cnt++;
 632                         return ADS7846_FILTER_REPEAT;
 633                 }
 634         }
 635 }
 636
 637 static int ads7846_no_filter(void *ads, int data_idx, int *val)
 638 {
 639         return ADS7846_FILTER_OK;
 640 }
 641
 642 static void ads7846_rx_val(void *ads)
 643 {
 644         struct ads7846 *ts = ads;
 645         struct spi_message *m;
 646         struct spi_transfer *t;
 647         u16 *rx_val;
 648         int val;
 649         int action;
 650         int status;
 651
 652         m = &ts->msg[ts->msg_idx];
 653         t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
 654         rx_val = t->rx_buf;
 655
 656         /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
 657          * built from two 8 bit values written msb-first.
 658          */
 659         val = be16_to_cpu(*rx_val) >> 3;
 660
 661         action = ts->filter(ts->filter_data, ts->msg_idx, &val);
 662         switch (action) {
 663         case ADS7846_FILTER_REPEAT:
 664                 break;
 665         case ADS7846_FILTER_IGNORE:
 666                 ts->tc.ignore = 1;
 667                 /* Last message will contain ads7846_rx() as the
 668                  * completion function.
 669                  */
 670                 m = ts->last_msg;
 671                 break;
 672         case ADS7846_FILTER_OK:
 673                 *rx_val = val;
 674                 ts->tc.ignore = 0;
 675                 m = &ts->msg[++ts->msg_idx];
 676                 break;
 677         default:
 678                 BUG();
 679         }
 680         status = spi_async(ts->spi, m);
 681         if (status)
 682                 dev_err(&ts->spi->dev, "spi_async --> %d\n",
 683                                 status);
 684 }
 685
 686 static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
 687 {
 688         struct ads7846  *ts = container_of(handle, struct ads7846, timer);
 689         int             status = 0;
 690
 691         spin_lock_irq(&ts->lock);
 692
 693         if (unlikely(!ts->get_pendown_state() ||
 694                      device_suspended(&ts->spi->dev))) {
 695                 if (ts->pendown) {
 696                         struct input_dev *input = ts->input;
 697
 698                         input_report_key(input, BTN_TOUCH, 0);
 699                         input_report_abs(input, ABS_PRESSURE, 0);
 700                         input_sync(input);
 701
 702                         ts->pendown = 0;
 703 #ifdef VERBOSE
 704                         dev_dbg(&ts->spi->dev, "UP\n");
 705 #endif
 706                 }
 707
 708                 /* measurement cycle ended */
 709                 if (!device_suspended(&ts->spi->dev)) {
 710                         ts->irq_disabled = 0;
 711                         enable_irq(ts->spi->irq);
 712                 }
 713                 ts->pending = 0;
 714         } else {
 715                 /* pen is still down, continue with the measurement */
 716                 ts->msg_idx = 0;
 717                 status = spi_async(ts->spi, &ts->msg[0]);
 718                 if (status)
 719                         dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
 720         }
 721
 722         spin_unlock_irq(&ts->lock);
 723         return HRTIMER_NORESTART;
 724 }
 725
 726 static irqreturn_t ads7846_irq(int irq, void *handle)
 727 {
 728         struct ads7846 *ts = handle;
 729         unsigned long flags;
 730
 731         spin_lock_irqsave(&ts->lock, flags);
 732         if (likely(ts->get_pendown_state())) {
 733                 if (!ts->irq_disabled) {
 734                         /* The ARM do_simple_IRQ() dispatcher doesn't act
 735                          * like the other dispatchers:  it will report IRQs
 736                          * even after they've been disabled.  We work around
 737                          * that here.  (The "generic irq" framework may help...)
 738                          */
 739                         ts->irq_disabled = 1;
 740                         disable_irq(ts->spi->irq);
 741                         ts->pending = 1;
 742                         hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
 743                                         HRTIMER_MODE_REL);
 744                 }
 745         }
 746         spin_unlock_irqrestore(&ts->lock, flags);
 747
 748         return IRQ_HANDLED;
 749 }
 750
 751 /*--------------------------------------------------------------------------*/
 752
 753 /* Must be called with ts->lock held */
 754 static void ads7846_disable(struct ads7846 *ts)
 755 {
 756         if (ts->disabled)
 757                 return;
 758
 759         ts->disabled = 1;
 760
 761         /* are we waiting for IRQ, or polling? */
 762         if (!ts->pending) {
 763                 ts->irq_disabled = 1;
 764                 disable_irq(ts->spi->irq);
 765         } else {
 766                 /* the timer will run at least once more, and
 767                  * leave everything in a clean state, IRQ disabled
 768                  */
 769                 while (ts->pending) {
 770                         spin_unlock_irq(&ts->lock);
 771                         msleep(1);
 772                         spin_lock_irq(&ts->lock);
 773                 }
 774         }
 775
 776         /* we know the chip's in lowpower mode since we always
 777          * leave it that way after every request
 778          */
 779
 780 }
 781
 782 /* Must be called with ts->lock held */
 783 static void ads7846_enable(struct ads7846 *ts)
 784 {
 785         if (!ts->disabled)
 786                 return;
 787
 788         ts->disabled = 0;
 789         ts->irq_disabled = 0;
 790         enable_irq(ts->spi->irq);
 791 }
 792
 793 static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
 794 {
 795         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 796
 797         spin_lock_irq(&ts->lock);
 798
 799         ts->is_suspended = 1;
 800         ads7846_disable(ts);
 801
 802         spin_unlock_irq(&ts->lock);
 803
 804         return 0;
 805
 806 }
 807
 808 static int ads7846_resume(struct spi_device *spi)
 809 {
 810         struct ads7846 *ts = dev_get_drvdata(&spi->dev);
 811
 812         spin_lock_irq(&ts->lock);
 813
 814         ts->is_suspended = 0;
 815         ads7846_enable(ts);
 816
 817         spin_unlock_irq(&ts->lock);
 818
 819         return 0;
 820 }
 821
 822 static int __devinit ads7846_probe(struct spi_device *spi)
 823 {
 824         struct ads7846                  *ts;
 825         struct input_dev                *input_dev;
 826         struct ads7846_platform_data    *pdata = spi->dev.platform_data;
 827         struct spi_message              *m;
 828         struct spi_transfer             *x;
 829         int                             vref;
 830         int                             err;
 831
 832         if (!spi->irq) {
 833                 dev_dbg(&spi->dev, "no IRQ?\n");
 834                 return -ENODEV;
 835         }
 836
 837         if (!pdata) {
 838                 dev_dbg(&spi->dev, "no platform data?\n");
 839                 return -ENODEV;
 840         }
 841
 842         /* don't exceed max specified sample rate */
 843         if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
 844                 dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
 845                                 (spi->max_speed_hz/SAMPLE_BITS)/1000);
 846                 return -EINVAL;
 847         }
 848
 849         /* REVISIT when the irq can be triggered active-low, or if for some
 850          * reason the touchscreen isn't hooked up, we don't need to access
 851          * the pendown state.
 852          */
 853         if (pdata->get_pendown_state == NULL) {
 854                 dev_dbg(&spi->dev, "no get_pendown_state function?\n");
 855                 return -EINVAL;
 856         }
 857
 858         /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
 859          * that even if the hardware can do that, the SPI controller driver
 860          * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 861          */
 862         spi->bits_per_word = 8;
 863         spi->mode = SPI_MODE_0;
 864         err = spi_setup(spi);
 865         if (err < 0)
 866                 return err;
 867
 868         ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
 869         input_dev = input_allocate_device();
 870         if (!ts || !input_dev) {
 871                 err = -ENOMEM;
 872                 goto err_free_mem;
 873         }
 874
 875         dev_set_drvdata(&spi->dev, ts);
 876
 877         ts->spi = spi;
 878         ts->input = input_dev;
 879
 880         hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 881         ts->timer.function = ads7846_timer;
 882
 883         spin_lock_init(&ts->lock);
 884
 885         ts->model = pdata->model ? : 7846;
 886         ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
 887         ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
 888         ts->pressure_max = pdata->pressure_max ? : ~0;
 889
 890         if (pdata->filter != NULL) {
 891                 if (pdata->filter_init != NULL) {
 892                         err = pdata->filter_init(pdata, &ts->filter_data);
 893                         if (err < 0)
 894                                 goto err_free_mem;
 895                 }
 896                 ts->filter = pdata->filter;
 897                 ts->filter_cleanup = pdata->filter_cleanup;
 898         } else if (pdata->debounce_max) {
 899                 ts->debounce_max = pdata->debounce_max;
 900                 if (ts->debounce_max < 2)
 901                         ts->debounce_max = 2;
 902                 ts->debounce_tol = pdata->debounce_tol;
 903                 ts->debounce_rep = pdata->debounce_rep;
 904                 ts->filter = ads7846_debounce;
 905                 ts->filter_data = ts;
 906         } else
 907                 ts->filter = ads7846_no_filter;
 908         ts->get_pendown_state = pdata->get_pendown_state;
 909
 910         if (pdata->penirq_recheck_delay_usecs)
 911                 ts->penirq_recheck_delay_usecs =
 912                                 pdata->penirq_recheck_delay_usecs;
 913
 914         snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
 915
 916         input_dev->name = "ADS784x Touchscreen";
 917         input_dev->phys = ts->phys;
 918         input_dev->dev.parent = &spi->dev;
 919
 920         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 921         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 922         input_set_abs_params(input_dev, ABS_X,
 923                         pdata->x_min ? : 0,
 924                         pdata->x_max ? : MAX_12BIT,
 925                         0, 0);
 926         input_set_abs_params(input_dev, ABS_Y,
 927                         pdata->y_min ? : 0,
 928                         pdata->y_max ? : MAX_12BIT,
 929                         0, 0);
 930         input_set_abs_params(input_dev, ABS_PRESSURE,
 931                         pdata->pressure_min, pdata->pressure_max, 0, 0);
 932
 933         vref = pdata->keep_vref_on;
 934
 935         /* set up the transfers to read touchscreen state; this assumes we
 936          * use formula #2 for pressure, not #3.
 937          */
 938         m = &ts->msg[0];
 939         x = ts->xfer;
 940
 941         spi_message_init(m);
 942
 943         /* y- still on; turn on only y+ (and ADC) */
 944         ts->read_y = READ_Y(vref);
 945         x->tx_buf = &ts->read_y;
 946         x->len = 1;
 947         spi_message_add_tail(x, m);
 948
 949         x++;
 950         x->rx_buf = &ts->tc.y;
 951         x->len = 2;
 952         spi_message_add_tail(x, m);
 953
 954         /* the first sample after switching drivers can be low quality;
 955          * optionally discard it, using a second one after the signals
 956          * have had enough time to stabilize.
 957          */
 958         if (pdata->settle_delay_usecs) {
 959                 x->delay_usecs = pdata->settle_delay_usecs;
 960
 961                 x++;
 962                 x->tx_buf = &ts->read_y;
 963                 x->len = 1;
 964                 spi_message_add_tail(x, m);
 965
 966                 x++;
 967                 x->rx_buf = &ts->tc.y;
 968                 x->len = 2;
 969                 spi_message_add_tail(x, m);
 970         }
 971
 972         m->complete = ads7846_rx_val;
 973         m->context = ts;
 974
 975         m++;
 976         spi_message_init(m);
 977
 978         /* turn y- off, x+ on, then leave in lowpower */
 979         x++;
 980         ts->read_x = READ_X(vref);
 981         x->tx_buf = &ts->read_x;
 982         x->len = 1;
 983         spi_message_add_tail(x, m);
 984
 985         x++;
 986         x->rx_buf = &ts->tc.x;
 987         x->len = 2;
 988         spi_message_add_tail(x, m);
 989
 990         /* ... maybe discard first sample ... */
 991         if (pdata->settle_delay_usecs) {
 992                 x->delay_usecs = pdata->settle_delay_usecs;
 993
 994                 x++;
 995                 x->tx_buf = &ts->read_x;
 996                 x->len = 1;
 997                 spi_message_add_tail(x, m);
 998
 999                 x++;
1000                 x->rx_buf = &ts->tc.x;
1001                 x->len = 2;
1002                 spi_message_add_tail(x, m);
1003         }
1004
1005         m->complete = ads7846_rx_val;
1006         m->context = ts;
1007
1008         /* turn y+ off, x- on; we'll use formula #2 */
1009         if (ts->model == 7846) {
1010                 m++;
1011                 spi_message_init(m);
1012
1013                 x++;
1014                 ts->read_z1 = READ_Z1(vref);
1015                 x->tx_buf = &ts->read_z1;
1016                 x->len = 1;
1017                 spi_message_add_tail(x, m);
1018
1019                 x++;
1020                 x->rx_buf = &ts->tc.z1;
1021                 x->len = 2;
1022                 spi_message_add_tail(x, m);
1023
1024                 /* ... maybe discard first sample ... */
1025                 if (pdata->settle_delay_usecs) {
1026                         x->delay_usecs = pdata->settle_delay_usecs;
1027
1028                         x++;
1029                         x->tx_buf = &ts->read_z1;
1030                         x->len = 1;
1031                         spi_message_add_tail(x, m);
1032
1033                         x++;
1034                         x->rx_buf = &ts->tc.z1;
1035                         x->len = 2;
1036                         spi_message_add_tail(x, m);
1037                 }
1038
1039                 m->complete = ads7846_rx_val;
1040                 m->context = ts;
1041
1042                 m++;
1043                 spi_message_init(m);
1044
1045                 x++;
1046                 ts->read_z2 = READ_Z2(vref);
1047                 x->tx_buf = &ts->read_z2;
1048                 x->len = 1;
1049                 spi_message_add_tail(x, m);
1050
1051                 x++;
1052                 x->rx_buf = &ts->tc.z2;
1053                 x->len = 2;
1054                 spi_message_add_tail(x, m);
1055
1056                 /* ... maybe discard first sample ... */
1057                 if (pdata->settle_delay_usecs) {
1058                         x->delay_usecs = pdata->settle_delay_usecs;
1059
1060                         x++;
1061                         x->tx_buf = &ts->read_z2;
1062                         x->len = 1;
1063                         spi_message_add_tail(x, m);
1064
1065                         x++;
1066                         x->rx_buf = &ts->tc.z2;
1067                         x->len = 2;
1068                         spi_message_add_tail(x, m);
1069                 }
1070
1071                 m->complete = ads7846_rx_val;
1072                 m->context = ts;
1073         }
1074
1075         /* power down */
1076         m++;
1077         spi_message_init(m);
1078
1079         x++;
1080         ts->pwrdown = PWRDOWN;
1081         x->tx_buf = &ts->pwrdown;
1082         x->len = 1;
1083         spi_message_add_tail(x, m);
1084
1085         x++;
1086         x->rx_buf = &ts->dummy;
1087         x->len = 2;
1088         CS_CHANGE(*x);
1089         spi_message_add_tail(x, m);
1090
1091         m->complete = ads7846_rx;
1092         m->context = ts;
1093
1094         ts->last_msg = m;
1095
1096         if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
1097                         spi->dev.driver->name, ts)) {
1098                 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
1099                 err = -EBUSY;
1100                 goto err_cleanup_filter;
1101         }
1102
1103         err = ads784x_hwmon_register(spi, ts);
1104         if (err)
1105                 goto err_free_irq;
1106
1107         dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
1108
1109         /* take a first sample, leaving nPENIRQ active and vREF off; avoid
1110          * the touchscreen, in case it's not connected.
1111          */
1112         (void) ads7846_read12_ser(&spi->dev,
1113                           READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
1114
1115         err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
1116         if (err)
1117                 goto err_remove_hwmon;
1118
1119         err = input_register_device(input_dev);
1120         if (err)
1121                 goto err_remove_attr_group;
1122
1123         return 0;
1124
1125  err_remove_attr_group:
1126         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1127  err_remove_hwmon:
1128         ads784x_hwmon_unregister(spi, ts);
1129  err_free_irq:
1130         free_irq(spi->irq, ts);
1131  err_cleanup_filter:
1132         if (ts->filter_cleanup)
1133                 ts->filter_cleanup(ts->filter_data);
1134  err_free_mem:
1135         input_free_device(input_dev);
1136         kfree(ts);
1137         return err;
1138 }
1139
1140 static int __devexit ads7846_remove(struct spi_device *spi)
1141 {
1142         struct ads7846          *ts = dev_get_drvdata(&spi->dev);
1143
1144         ads784x_hwmon_unregister(spi, ts);
1145         input_unregister_device(ts->input);
1146
1147         ads7846_suspend(spi, PMSG_SUSPEND);
1148
1149         sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
1150
1151         free_irq(ts->spi->irq, ts);
1152         /* suspend left the IRQ disabled */
1153         enable_irq(ts->spi->irq);
1154
1155         if (ts->filter_cleanup)
1156                 ts->filter_cleanup(ts->filter_data);
1157
1158         kfree(ts);
1159
1160         dev_dbg(&spi->dev, "unregistered touchscreen\n");
1161         return 0;
1162 }
1163
1164 static struct spi_driver ads7846_driver = {
1165         .driver = {
1166                 .name   = "ads7846",
1167                 .bus    = &spi_bus_type,
1168                 .owner  = THIS_MODULE,
1169         },
1170         .probe          = ads7846_probe,
1171         .remove         = __devexit_p(ads7846_remove),
1172         .suspend        = ads7846_suspend,
1173         .resume         = ads7846_resume,
1174 };
1175
1176 static int __init ads7846_init(void)
1177 {
1178         /* grr, board-specific init should stay out of drivers!! */
1179
1180 #ifdef  CONFIG_ARCH_OMAP
1181         if (machine_is_omap_osk()) {
1182                 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
1183                 omap_request_gpio(4);
1184                 omap_set_gpio_direction(4, 1);
1185                 omap_request_gpio(6);
1186                 omap_set_gpio_direction(6, 1);
1187         }
1188         // also TI 1510 Innovator, bitbanging through FPGA
1189         // also Nokia 770
1190         // also Palm Tungsten T2
1191 #endif
1192
1193         // PXA:
1194         // also Dell Axim X50
1195         // also HP iPaq H191x/H192x/H415x/H435x
1196         // also Intel Lubbock (additional to UCB1400; as temperature sensor)
1197         // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
1198
1199         // Atmel at91sam9261-EK uses ads7843
1200
1201         // also various AMD Au1x00 devel boards
1202
1203         return spi_register_driver(&ads7846_driver);
1204 }
1205 module_init(ads7846_init);
1206
1207 static void __exit ads7846_exit(void)
1208 {
1209         spi_unregister_driver(&ads7846_driver);
1210
1211 #ifdef  CONFIG_ARCH_OMAP
1212         if (machine_is_omap_osk()) {
1213                 omap_free_gpio(4);
1214                 omap_free_gpio(6);
1215         }
1216 #endif
1217
1218 }
1219 module_exit(ads7846_exit);
1220
1221 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
1222 MODULE_LICENSE("GPL");