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/types.h> 21 #include <linux/hwmon.h> 22 #include <linux/init.h> 23 #include <linux/err.h> 24 #include <linux/sched.h> 25 #include <linux/delay.h> 26 #include <linux/input.h> 27 #include <linux/interrupt.h> 28 #include <linux/slab.h> 29 #include <linux/pm.h> 30 #include <linux/gpio.h> 31 #include <linux/spi/spi.h> 32 #include <linux/spi/ads7846.h> 33 #include <linux/regulator/consumer.h> 34 #include <asm/irq.h> 35 36 /* 37 * This code has been heavily tested on a Nokia 770, and lightly 38 * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz). 39 * TSC2046 is just newer ads7846 silicon. 40 * Support for ads7843 tested on Atmel at91sam926x-EK. 41 * Support for ads7845 has only been stubbed in. 42 * Support for Analog Devices AD7873 and AD7843 tested. 43 * 44 * IRQ handling needs a workaround because of a shortcoming in handling 45 * edge triggered IRQs on some platforms like the OMAP1/2. These 46 * platforms don't handle the ARM lazy IRQ disabling properly, thus we 47 * have to maintain our own SW IRQ disabled status. This should be 48 * removed as soon as the affected platform's IRQ handling is fixed. 49 * 50 * App note sbaa036 talks in more detail about accurate sampling... 51 * that ought to help in situations like LCDs inducing noise (which 52 * can also be helped by using synch signals) and more generally. 53 * This driver tries to utilize the measures described in the app 54 * note. The strength of filtering can be set in the board-* specific 55 * files. 56 */ 57 58 #define TS_POLL_DELAY 1 /* ms delay before the first sample */ 59 #define TS_POLL_PERIOD 5 /* ms delay between samples */ 60 61 /* this driver doesn't aim at the peak continuous sample rate */ 62 #define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */) 63 64 struct ts_event { 65 /* 66 * For portability, we can't read 12 bit values using SPI (which 67 * would make the controller deliver them as native byte order u16 68 * with msbs zeroed). Instead, we read them as two 8-bit values, 69 * *** WHICH NEED BYTESWAPPING *** and range adjustment. 70 */ 71 u16 x; 72 u16 y; 73 u16 z1, z2; 74 bool ignore; 75 u8 x_buf[3]; 76 u8 y_buf[3]; 77 }; 78 79 /* 80 * We allocate this separately to avoid cache line sharing issues when 81 * driver is used with DMA-based SPI controllers (like atmel_spi) on 82 * systems where main memory is not DMA-coherent (most non-x86 boards). 83 */ 84 struct ads7846_packet { 85 u8 read_x, read_y, read_z1, read_z2, pwrdown; 86 u16 dummy; /* for the pwrdown read */ 87 struct ts_event tc; 88 /* for ads7845 with mpc5121 psc spi we use 3-byte buffers */ 89 u8 read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3]; 90 }; 91 92 struct ads7846 { 93 struct input_dev *input; 94 char phys[32]; 95 char name[32]; 96 97 struct spi_device *spi; 98 struct regulator *reg; 99 100 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE) 101 struct attribute_group *attr_group; 102 struct device *hwmon; 103 #endif 104 105 u16 model; 106 u16 vref_mv; 107 u16 vref_delay_usecs; 108 u16 x_plate_ohms; 109 u16 pressure_max; 110 111 bool swap_xy; 112 bool use_internal; 113 114 struct ads7846_packet *packet; 115 116 struct spi_transfer xfer[18]; 117 struct spi_message msg[5]; 118 int msg_count; 119 wait_queue_head_t wait; 120 121 bool pendown; 122 123 int read_cnt; 124 int read_rep; 125 int last_read; 126 127 u16 debounce_max; 128 u16 debounce_tol; 129 u16 debounce_rep; 130 131 u16 penirq_recheck_delay_usecs; 132 133 struct mutex lock; 134 bool stopped; /* P: lock */ 135 bool disabled; /* P: lock */ 136 bool suspended; /* P: lock */ 137 138 int (*filter)(void *data, int data_idx, int *val); 139 void *filter_data; 140 void (*filter_cleanup)(void *data); 141 int (*get_pendown_state)(void); 142 int gpio_pendown; 143 144 void (*wait_for_sync)(void); 145 }; 146 147 /* leave chip selected when we're done, for quicker re-select? */ 148 #if 0 149 #define CS_CHANGE(xfer) ((xfer).cs_change = 1) 150 #else 151 #define CS_CHANGE(xfer) ((xfer).cs_change = 0) 152 #endif 153 154 /*--------------------------------------------------------------------------*/ 155 156 /* The ADS7846 has touchscreen and other sensors. 157 * Earlier ads784x chips are somewhat compatible. 158 */ 159 #define ADS_START (1 << 7) 160 #define ADS_A2A1A0_d_y (1 << 4) /* differential */ 161 #define ADS_A2A1A0_d_z1 (3 << 4) /* differential */ 162 #define ADS_A2A1A0_d_z2 (4 << 4) /* differential */ 163 #define ADS_A2A1A0_d_x (5 << 4) /* differential */ 164 #define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */ 165 #define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */ 166 #define ADS_A2A1A0_vaux (6 << 4) /* non-differential */ 167 #define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */ 168 #define ADS_8_BIT (1 << 3) 169 #define ADS_12_BIT (0 << 3) 170 #define ADS_SER (1 << 2) /* non-differential */ 171 #define ADS_DFR (0 << 2) /* differential */ 172 #define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */ 173 #define ADS_PD10_ADC_ON (1 << 0) /* ADC on */ 174 #define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */ 175 #define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */ 176 177 #define MAX_12BIT ((1<<12)-1) 178 179 /* leave ADC powered up (disables penirq) between differential samples */ 180 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \ 181 | ADS_12_BIT | ADS_DFR | \ 182 (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0)) 183 184 #define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref)) 185 #define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref)) 186 #define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref)) 187 188 #define READ_X(vref) (READ_12BIT_DFR(x, 1, vref)) 189 #define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */ 190 191 /* single-ended samples need to first power up reference voltage; 192 * we leave both ADC and VREF powered 193 */ 194 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \ 195 | ADS_12_BIT | ADS_SER) 196 197 #define REF_ON (READ_12BIT_DFR(x, 1, 1)) 198 #define REF_OFF (READ_12BIT_DFR(y, 0, 0)) 199 200 /* Must be called with ts->lock held */ 201 static void ads7846_stop(struct ads7846 *ts) 202 { 203 if (!ts->disabled && !ts->suspended) { 204 /* Signal IRQ thread to stop polling and disable the handler. */ 205 ts->stopped = true; 206 mb(); 207 wake_up(&ts->wait); 208 disable_irq(ts->spi->irq); 209 } 210 } 211 212 /* Must be called with ts->lock held */ 213 static void ads7846_restart(struct ads7846 *ts) 214 { 215 if (!ts->disabled && !ts->suspended) { 216 /* Tell IRQ thread that it may poll the device. */ 217 ts->stopped = false; 218 mb(); 219 enable_irq(ts->spi->irq); 220 } 221 } 222 223 /* Must be called with ts->lock held */ 224 static void __ads7846_disable(struct ads7846 *ts) 225 { 226 ads7846_stop(ts); 227 regulator_disable(ts->reg); 228 229 /* 230 * We know the chip's in low power mode since we always 231 * leave it that way after every request 232 */ 233 } 234 235 /* Must be called with ts->lock held */ 236 static void __ads7846_enable(struct ads7846 *ts) 237 { 238 regulator_enable(ts->reg); 239 ads7846_restart(ts); 240 } 241 242 static void ads7846_disable(struct ads7846 *ts) 243 { 244 mutex_lock(&ts->lock); 245 246 if (!ts->disabled) { 247 248 if (!ts->suspended) 249 __ads7846_disable(ts); 250 251 ts->disabled = true; 252 } 253 254 mutex_unlock(&ts->lock); 255 } 256 257 static void ads7846_enable(struct ads7846 *ts) 258 { 259 mutex_lock(&ts->lock); 260 261 if (ts->disabled) { 262 263 ts->disabled = false; 264 265 if (!ts->suspended) 266 __ads7846_enable(ts); 267 } 268 269 mutex_unlock(&ts->lock); 270 } 271 272 /*--------------------------------------------------------------------------*/ 273 274 /* 275 * Non-touchscreen sensors only use single-ended conversions. 276 * The range is GND..vREF. The ads7843 and ads7835 must use external vREF; 277 * ads7846 lets that pin be unconnected, to use internal vREF. 278 */ 279 280 struct ser_req { 281 u8 ref_on; 282 u8 command; 283 u8 ref_off; 284 u16 scratch; 285 __be16 sample; 286 struct spi_message msg; 287 struct spi_transfer xfer[6]; 288 }; 289 290 struct ads7845_ser_req { 291 u8 command[3]; 292 u8 pwrdown[3]; 293 u8 sample[3]; 294 struct spi_message msg; 295 struct spi_transfer xfer[2]; 296 }; 297 298 static int ads7846_read12_ser(struct device *dev, unsigned command) 299 { 300 struct spi_device *spi = to_spi_device(dev); 301 struct ads7846 *ts = dev_get_drvdata(dev); 302 struct ser_req *req; 303 int status; 304 305 req = kzalloc(sizeof *req, GFP_KERNEL); 306 if (!req) 307 return -ENOMEM; 308 309 spi_message_init(&req->msg); 310 311 /* maybe turn on internal vREF, and let it settle */ 312 if (ts->use_internal) { 313 req->ref_on = REF_ON; 314 req->xfer[0].tx_buf = &req->ref_on; 315 req->xfer[0].len = 1; 316 spi_message_add_tail(&req->xfer[0], &req->msg); 317 318 req->xfer[1].rx_buf = &req->scratch; 319 req->xfer[1].len = 2; 320 321 /* for 1uF, settle for 800 usec; no cap, 100 usec. */ 322 req->xfer[1].delay_usecs = ts->vref_delay_usecs; 323 spi_message_add_tail(&req->xfer[1], &req->msg); 324 325 /* Enable reference voltage */ 326 command |= ADS_PD10_REF_ON; 327 } 328 329 /* Enable ADC in every case */ 330 command |= ADS_PD10_ADC_ON; 331 332 /* take sample */ 333 req->command = (u8) command; 334 req->xfer[2].tx_buf = &req->command; 335 req->xfer[2].len = 1; 336 spi_message_add_tail(&req->xfer[2], &req->msg); 337 338 req->xfer[3].rx_buf = &req->sample; 339 req->xfer[3].len = 2; 340 spi_message_add_tail(&req->xfer[3], &req->msg); 341 342 /* REVISIT: take a few more samples, and compare ... */ 343 344 /* converter in low power mode & enable PENIRQ */ 345 req->ref_off = PWRDOWN; 346 req->xfer[4].tx_buf = &req->ref_off; 347 req->xfer[4].len = 1; 348 spi_message_add_tail(&req->xfer[4], &req->msg); 349 350 req->xfer[5].rx_buf = &req->scratch; 351 req->xfer[5].len = 2; 352 CS_CHANGE(req->xfer[5]); 353 spi_message_add_tail(&req->xfer[5], &req->msg); 354 355 mutex_lock(&ts->lock); 356 ads7846_stop(ts); 357 status = spi_sync(spi, &req->msg); 358 ads7846_restart(ts); 359 mutex_unlock(&ts->lock); 360 361 if (status == 0) { 362 /* on-wire is a must-ignore bit, a BE12 value, then padding */ 363 status = be16_to_cpu(req->sample); 364 status = status >> 3; 365 status &= 0x0fff; 366 } 367 368 kfree(req); 369 return status; 370 } 371 372 static int ads7845_read12_ser(struct device *dev, unsigned command) 373 { 374 struct spi_device *spi = to_spi_device(dev); 375 struct ads7846 *ts = dev_get_drvdata(dev); 376 struct ads7845_ser_req *req; 377 int status; 378 379 req = kzalloc(sizeof *req, GFP_KERNEL); 380 if (!req) 381 return -ENOMEM; 382 383 spi_message_init(&req->msg); 384 385 req->command[0] = (u8) command; 386 req->xfer[0].tx_buf = req->command; 387 req->xfer[0].rx_buf = req->sample; 388 req->xfer[0].len = 3; 389 spi_message_add_tail(&req->xfer[0], &req->msg); 390 391 mutex_lock(&ts->lock); 392 ads7846_stop(ts); 393 status = spi_sync(spi, &req->msg); 394 ads7846_restart(ts); 395 mutex_unlock(&ts->lock); 396 397 if (status == 0) { 398 /* BE12 value, then padding */ 399 status = be16_to_cpu(*((u16 *)&req->sample[1])); 400 status = status >> 3; 401 status &= 0x0fff; 402 } 403 404 kfree(req); 405 return status; 406 } 407 408 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE) 409 410 #define SHOW(name, var, adjust) static ssize_t \ 411 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \ 412 { \ 413 struct ads7846 *ts = dev_get_drvdata(dev); \ 414 ssize_t v = ads7846_read12_ser(dev, \ 415 READ_12BIT_SER(var)); \ 416 if (v < 0) \ 417 return v; \ 418 return sprintf(buf, "%u\n", adjust(ts, v)); \ 419 } \ 420 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL); 421 422 423 /* Sysfs conventions report temperatures in millidegrees Celsius. 424 * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high 425 * accuracy scheme without calibration data. For now we won't try either; 426 * userspace sees raw sensor values, and must scale/calibrate appropriately. 427 */ 428 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v) 429 { 430 return v; 431 } 432 433 SHOW(temp0, temp0, null_adjust) /* temp1_input */ 434 SHOW(temp1, temp1, null_adjust) /* temp2_input */ 435 436 437 /* sysfs conventions report voltages in millivolts. We can convert voltages 438 * if we know vREF. userspace may need to scale vAUX to match the board's 439 * external resistors; we assume that vBATT only uses the internal ones. 440 */ 441 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v) 442 { 443 unsigned retval = v; 444 445 /* external resistors may scale vAUX into 0..vREF */ 446 retval *= ts->vref_mv; 447 retval = retval >> 12; 448 449 return retval; 450 } 451 452 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v) 453 { 454 unsigned retval = vaux_adjust(ts, v); 455 456 /* ads7846 has a resistor ladder to scale this signal down */ 457 if (ts->model == 7846) 458 retval *= 4; 459 460 return retval; 461 } 462 463 SHOW(in0_input, vaux, vaux_adjust) 464 SHOW(in1_input, vbatt, vbatt_adjust) 465 466 static struct attribute *ads7846_attributes[] = { 467 &dev_attr_temp0.attr, 468 &dev_attr_temp1.attr, 469 &dev_attr_in0_input.attr, 470 &dev_attr_in1_input.attr, 471 NULL, 472 }; 473 474 static struct attribute_group ads7846_attr_group = { 475 .attrs = ads7846_attributes, 476 }; 477 478 static struct attribute *ads7843_attributes[] = { 479 &dev_attr_in0_input.attr, 480 &dev_attr_in1_input.attr, 481 NULL, 482 }; 483 484 static struct attribute_group ads7843_attr_group = { 485 .attrs = ads7843_attributes, 486 }; 487 488 static struct attribute *ads7845_attributes[] = { 489 &dev_attr_in0_input.attr, 490 NULL, 491 }; 492 493 static struct attribute_group ads7845_attr_group = { 494 .attrs = ads7845_attributes, 495 }; 496 497 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts) 498 { 499 struct device *hwmon; 500 int err; 501 502 /* hwmon sensors need a reference voltage */ 503 switch (ts->model) { 504 case 7846: 505 if (!ts->vref_mv) { 506 dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n"); 507 ts->vref_mv = 2500; 508 ts->use_internal = true; 509 } 510 break; 511 case 7845: 512 case 7843: 513 if (!ts->vref_mv) { 514 dev_warn(&spi->dev, 515 "external vREF for ADS%d not specified\n", 516 ts->model); 517 return 0; 518 } 519 break; 520 } 521 522 /* different chips have different sensor groups */ 523 switch (ts->model) { 524 case 7846: 525 ts->attr_group = &ads7846_attr_group; 526 break; 527 case 7845: 528 ts->attr_group = &ads7845_attr_group; 529 break; 530 case 7843: 531 ts->attr_group = &ads7843_attr_group; 532 break; 533 default: 534 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model); 535 return 0; 536 } 537 538 err = sysfs_create_group(&spi->dev.kobj, ts->attr_group); 539 if (err) 540 return err; 541 542 hwmon = hwmon_device_register(&spi->dev); 543 if (IS_ERR(hwmon)) { 544 sysfs_remove_group(&spi->dev.kobj, ts->attr_group); 545 return PTR_ERR(hwmon); 546 } 547 548 ts->hwmon = hwmon; 549 return 0; 550 } 551 552 static void ads784x_hwmon_unregister(struct spi_device *spi, 553 struct ads7846 *ts) 554 { 555 if (ts->hwmon) { 556 sysfs_remove_group(&spi->dev.kobj, ts->attr_group); 557 hwmon_device_unregister(ts->hwmon); 558 } 559 } 560 561 #else 562 static inline int ads784x_hwmon_register(struct spi_device *spi, 563 struct ads7846 *ts) 564 { 565 return 0; 566 } 567 568 static inline void ads784x_hwmon_unregister(struct spi_device *spi, 569 struct ads7846 *ts) 570 { 571 } 572 #endif 573 574 static ssize_t ads7846_pen_down_show(struct device *dev, 575 struct device_attribute *attr, char *buf) 576 { 577 struct ads7846 *ts = dev_get_drvdata(dev); 578 579 return sprintf(buf, "%u\n", ts->pendown); 580 } 581 582 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL); 583 584 static ssize_t ads7846_disable_show(struct device *dev, 585 struct device_attribute *attr, char *buf) 586 { 587 struct ads7846 *ts = dev_get_drvdata(dev); 588 589 return sprintf(buf, "%u\n", ts->disabled); 590 } 591 592 static ssize_t ads7846_disable_store(struct device *dev, 593 struct device_attribute *attr, 594 const char *buf, size_t count) 595 { 596 struct ads7846 *ts = dev_get_drvdata(dev); 597 unsigned long i; 598 599 if (strict_strtoul(buf, 10, &i)) 600 return -EINVAL; 601 602 if (i) 603 ads7846_disable(ts); 604 else 605 ads7846_enable(ts); 606 607 return count; 608 } 609 610 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store); 611 612 static struct attribute *ads784x_attributes[] = { 613 &dev_attr_pen_down.attr, 614 &dev_attr_disable.attr, 615 NULL, 616 }; 617 618 static struct attribute_group ads784x_attr_group = { 619 .attrs = ads784x_attributes, 620 }; 621 622 /*--------------------------------------------------------------------------*/ 623 624 static int get_pendown_state(struct ads7846 *ts) 625 { 626 if (ts->get_pendown_state) 627 return ts->get_pendown_state(); 628 629 return !gpio_get_value(ts->gpio_pendown); 630 } 631 632 static void null_wait_for_sync(void) 633 { 634 } 635 636 static int ads7846_debounce_filter(void *ads, int data_idx, int *val) 637 { 638 struct ads7846 *ts = ads; 639 640 if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) { 641 /* Start over collecting consistent readings. */ 642 ts->read_rep = 0; 643 /* 644 * Repeat it, if this was the first read or the read 645 * wasn't consistent enough. 646 */ 647 if (ts->read_cnt < ts->debounce_max) { 648 ts->last_read = *val; 649 ts->read_cnt++; 650 return ADS7846_FILTER_REPEAT; 651 } else { 652 /* 653 * Maximum number of debouncing reached and still 654 * not enough number of consistent readings. Abort 655 * the whole sample, repeat it in the next sampling 656 * period. 657 */ 658 ts->read_cnt = 0; 659 return ADS7846_FILTER_IGNORE; 660 } 661 } else { 662 if (++ts->read_rep > ts->debounce_rep) { 663 /* 664 * Got a good reading for this coordinate, 665 * go for the next one. 666 */ 667 ts->read_cnt = 0; 668 ts->read_rep = 0; 669 return ADS7846_FILTER_OK; 670 } else { 671 /* Read more values that are consistent. */ 672 ts->read_cnt++; 673 return ADS7846_FILTER_REPEAT; 674 } 675 } 676 } 677 678 static int ads7846_no_filter(void *ads, int data_idx, int *val) 679 { 680 return ADS7846_FILTER_OK; 681 } 682 683 static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m) 684 { 685 struct spi_transfer *t = 686 list_entry(m->transfers.prev, struct spi_transfer, transfer_list); 687 688 if (ts->model == 7845) { 689 return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3; 690 } else { 691 /* 692 * adjust: on-wire is a must-ignore bit, a BE12 value, then 693 * padding; built from two 8 bit values written msb-first. 694 */ 695 return be16_to_cpup((__be16 *)t->rx_buf) >> 3; 696 } 697 } 698 699 static void ads7846_update_value(struct spi_message *m, int val) 700 { 701 struct spi_transfer *t = 702 list_entry(m->transfers.prev, struct spi_transfer, transfer_list); 703 704 *(u16 *)t->rx_buf = val; 705 } 706 707 static void ads7846_read_state(struct ads7846 *ts) 708 { 709 struct ads7846_packet *packet = ts->packet; 710 struct spi_message *m; 711 int msg_idx = 0; 712 int val; 713 int action; 714 int error; 715 716 while (msg_idx < ts->msg_count) { 717 718 ts->wait_for_sync(); 719 720 m = &ts->msg[msg_idx]; 721 error = spi_sync(ts->spi, m); 722 if (error) { 723 dev_err(&ts->spi->dev, "spi_async --> %d\n", error); 724 packet->tc.ignore = true; 725 return; 726 } 727 728 /* 729 * Last message is power down request, no need to convert 730 * or filter the value. 731 */ 732 if (msg_idx < ts->msg_count - 1) { 733 734 val = ads7846_get_value(ts, m); 735 736 action = ts->filter(ts->filter_data, msg_idx, &val); 737 switch (action) { 738 case ADS7846_FILTER_REPEAT: 739 continue; 740 741 case ADS7846_FILTER_IGNORE: 742 packet->tc.ignore = true; 743 msg_idx = ts->msg_count - 1; 744 continue; 745 746 case ADS7846_FILTER_OK: 747 ads7846_update_value(m, val); 748 packet->tc.ignore = false; 749 msg_idx++; 750 break; 751 752 default: 753 BUG(); 754 } 755 } else { 756 msg_idx++; 757 } 758 } 759 } 760 761 static void ads7846_report_state(struct ads7846 *ts) 762 { 763 struct ads7846_packet *packet = ts->packet; 764 unsigned int Rt; 765 u16 x, y, z1, z2; 766 767 /* 768 * ads7846_get_value() does in-place conversion (including byte swap) 769 * from on-the-wire format as part of debouncing to get stable 770 * readings. 771 */ 772 if (ts->model == 7845) { 773 x = *(u16 *)packet->tc.x_buf; 774 y = *(u16 *)packet->tc.y_buf; 775 z1 = 0; 776 z2 = 0; 777 } else { 778 x = packet->tc.x; 779 y = packet->tc.y; 780 z1 = packet->tc.z1; 781 z2 = packet->tc.z2; 782 } 783 784 /* range filtering */ 785 if (x == MAX_12BIT) 786 x = 0; 787 788 if (ts->model == 7843) { 789 Rt = ts->pressure_max / 2; 790 } else if (ts->model == 7845) { 791 if (get_pendown_state(ts)) 792 Rt = ts->pressure_max / 2; 793 else 794 Rt = 0; 795 dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt); 796 } else if (likely(x && z1)) { 797 /* compute touch pressure resistance using equation #2 */ 798 Rt = z2; 799 Rt -= z1; 800 Rt *= x; 801 Rt *= ts->x_plate_ohms; 802 Rt /= z1; 803 Rt = (Rt + 2047) >> 12; 804 } else { 805 Rt = 0; 806 } 807 808 /* 809 * Sample found inconsistent by debouncing or pressure is beyond 810 * the maximum. Don't report it to user space, repeat at least 811 * once more the measurement 812 */ 813 if (packet->tc.ignore || Rt > ts->pressure_max) { 814 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n", 815 packet->tc.ignore, Rt); 816 return; 817 } 818 819 /* 820 * Maybe check the pendown state before reporting. This discards 821 * false readings when the pen is lifted. 822 */ 823 if (ts->penirq_recheck_delay_usecs) { 824 udelay(ts->penirq_recheck_delay_usecs); 825 if (!get_pendown_state(ts)) 826 Rt = 0; 827 } 828 829 /* 830 * NOTE: We can't rely on the pressure to determine the pen down 831 * state, even this controller has a pressure sensor. The pressure 832 * value can fluctuate for quite a while after lifting the pen and 833 * in some cases may not even settle at the expected value. 834 * 835 * The only safe way to check for the pen up condition is in the 836 * timer by reading the pen signal state (it's a GPIO _and_ IRQ). 837 */ 838 if (Rt) { 839 struct input_dev *input = ts->input; 840 841 if (ts->swap_xy) 842 swap(x, y); 843 844 if (!ts->pendown) { 845 input_report_key(input, BTN_TOUCH, 1); 846 ts->pendown = true; 847 dev_vdbg(&ts->spi->dev, "DOWN\n"); 848 } 849 850 input_report_abs(input, ABS_X, x); 851 input_report_abs(input, ABS_Y, y); 852 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt); 853 854 input_sync(input); 855 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt); 856 } 857 } 858 859 static irqreturn_t ads7846_hard_irq(int irq, void *handle) 860 { 861 struct ads7846 *ts = handle; 862 863 return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED; 864 } 865 866 867 static irqreturn_t ads7846_irq(int irq, void *handle) 868 { 869 struct ads7846 *ts = handle; 870 871 /* Start with a small delay before checking pendown state */ 872 msleep(TS_POLL_DELAY); 873 874 while (!ts->stopped && get_pendown_state(ts)) { 875 876 /* pen is down, continue with the measurement */ 877 ads7846_read_state(ts); 878 879 if (!ts->stopped) 880 ads7846_report_state(ts); 881 882 wait_event_timeout(ts->wait, ts->stopped, 883 msecs_to_jiffies(TS_POLL_PERIOD)); 884 } 885 886 if (ts->pendown) { 887 struct input_dev *input = ts->input; 888 889 input_report_key(input, BTN_TOUCH, 0); 890 input_report_abs(input, ABS_PRESSURE, 0); 891 input_sync(input); 892 893 ts->pendown = false; 894 dev_vdbg(&ts->spi->dev, "UP\n"); 895 } 896 897 return IRQ_HANDLED; 898 } 899 900 #ifdef CONFIG_PM_SLEEP 901 static int ads7846_suspend(struct device *dev) 902 { 903 struct ads7846 *ts = dev_get_drvdata(dev); 904 905 mutex_lock(&ts->lock); 906 907 if (!ts->suspended) { 908 909 if (!ts->disabled) 910 __ads7846_disable(ts); 911 912 if (device_may_wakeup(&ts->spi->dev)) 913 enable_irq_wake(ts->spi->irq); 914 915 ts->suspended = true; 916 } 917 918 mutex_unlock(&ts->lock); 919 920 return 0; 921 } 922 923 static int ads7846_resume(struct device *dev) 924 { 925 struct ads7846 *ts = dev_get_drvdata(dev); 926 927 mutex_lock(&ts->lock); 928 929 if (ts->suspended) { 930 931 ts->suspended = false; 932 933 if (device_may_wakeup(&ts->spi->dev)) 934 disable_irq_wake(ts->spi->irq); 935 936 if (!ts->disabled) 937 __ads7846_enable(ts); 938 } 939 940 mutex_unlock(&ts->lock); 941 942 return 0; 943 } 944 #endif 945 946 static SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume); 947 948 static int __devinit ads7846_setup_pendown(struct spi_device *spi, struct ads7846 *ts) 949 { 950 struct ads7846_platform_data *pdata = spi->dev.platform_data; 951 int err; 952 953 /* 954 * REVISIT when the irq can be triggered active-low, or if for some 955 * reason the touchscreen isn't hooked up, we don't need to access 956 * the pendown state. 957 */ 958 959 if (pdata->get_pendown_state) { 960 ts->get_pendown_state = pdata->get_pendown_state; 961 } else if (gpio_is_valid(pdata->gpio_pendown)) { 962 963 err = gpio_request(pdata->gpio_pendown, "ads7846_pendown"); 964 if (err) { 965 dev_err(&spi->dev, "failed to request pendown GPIO%d\n", 966 pdata->gpio_pendown); 967 return err; 968 } 969 970 ts->gpio_pendown = pdata->gpio_pendown; 971 972 } else { 973 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n"); 974 return -EINVAL; 975 } 976 977 return 0; 978 } 979 980 /* 981 * Set up the transfers to read touchscreen state; this assumes we 982 * use formula #2 for pressure, not #3. 983 */ 984 static void __devinit ads7846_setup_spi_msg(struct ads7846 *ts, 985 const struct ads7846_platform_data *pdata) 986 { 987 struct spi_message *m = &ts->msg[0]; 988 struct spi_transfer *x = ts->xfer; 989 struct ads7846_packet *packet = ts->packet; 990 int vref = pdata->keep_vref_on; 991 992 if (ts->model == 7873) { 993 /* 994 * The AD7873 is almost identical to the ADS7846 995 * keep VREF off during differential/ratiometric 996 * conversion modes. 997 */ 998 ts->model = 7846; 999 vref = 0; 1000 } 1001 1002 ts->msg_count = 1; 1003 spi_message_init(m); 1004 m->context = ts; 1005 1006 if (ts->model == 7845) { 1007 packet->read_y_cmd[0] = READ_Y(vref); 1008 packet->read_y_cmd[1] = 0; 1009 packet->read_y_cmd[2] = 0; 1010 x->tx_buf = &packet->read_y_cmd[0]; 1011 x->rx_buf = &packet->tc.y_buf[0]; 1012 x->len = 3; 1013 spi_message_add_tail(x, m); 1014 } else { 1015 /* y- still on; turn on only y+ (and ADC) */ 1016 packet->read_y = READ_Y(vref); 1017 x->tx_buf = &packet->read_y; 1018 x->len = 1; 1019 spi_message_add_tail(x, m); 1020 1021 x++; 1022 x->rx_buf = &packet->tc.y; 1023 x->len = 2; 1024 spi_message_add_tail(x, m); 1025 } 1026 1027 /* 1028 * The first sample after switching drivers can be low quality; 1029 * optionally discard it, using a second one after the signals 1030 * have had enough time to stabilize. 1031 */ 1032 if (pdata->settle_delay_usecs) { 1033 x->delay_usecs = pdata->settle_delay_usecs; 1034 1035 x++; 1036 x->tx_buf = &packet->read_y; 1037 x->len = 1; 1038 spi_message_add_tail(x, m); 1039 1040 x++; 1041 x->rx_buf = &packet->tc.y; 1042 x->len = 2; 1043 spi_message_add_tail(x, m); 1044 } 1045 1046 ts->msg_count++; 1047 m++; 1048 spi_message_init(m); 1049 m->context = ts; 1050 1051 if (ts->model == 7845) { 1052 x++; 1053 packet->read_x_cmd[0] = READ_X(vref); 1054 packet->read_x_cmd[1] = 0; 1055 packet->read_x_cmd[2] = 0; 1056 x->tx_buf = &packet->read_x_cmd[0]; 1057 x->rx_buf = &packet->tc.x_buf[0]; 1058 x->len = 3; 1059 spi_message_add_tail(x, m); 1060 } else { 1061 /* turn y- off, x+ on, then leave in lowpower */ 1062 x++; 1063 packet->read_x = READ_X(vref); 1064 x->tx_buf = &packet->read_x; 1065 x->len = 1; 1066 spi_message_add_tail(x, m); 1067 1068 x++; 1069 x->rx_buf = &packet->tc.x; 1070 x->len = 2; 1071 spi_message_add_tail(x, m); 1072 } 1073 1074 /* ... maybe discard first sample ... */ 1075 if (pdata->settle_delay_usecs) { 1076 x->delay_usecs = pdata->settle_delay_usecs; 1077 1078 x++; 1079 x->tx_buf = &packet->read_x; 1080 x->len = 1; 1081 spi_message_add_tail(x, m); 1082 1083 x++; 1084 x->rx_buf = &packet->tc.x; 1085 x->len = 2; 1086 spi_message_add_tail(x, m); 1087 } 1088 1089 /* turn y+ off, x- on; we'll use formula #2 */ 1090 if (ts->model == 7846) { 1091 ts->msg_count++; 1092 m++; 1093 spi_message_init(m); 1094 m->context = ts; 1095 1096 x++; 1097 packet->read_z1 = READ_Z1(vref); 1098 x->tx_buf = &packet->read_z1; 1099 x->len = 1; 1100 spi_message_add_tail(x, m); 1101 1102 x++; 1103 x->rx_buf = &packet->tc.z1; 1104 x->len = 2; 1105 spi_message_add_tail(x, m); 1106 1107 /* ... maybe discard first sample ... */ 1108 if (pdata->settle_delay_usecs) { 1109 x->delay_usecs = pdata->settle_delay_usecs; 1110 1111 x++; 1112 x->tx_buf = &packet->read_z1; 1113 x->len = 1; 1114 spi_message_add_tail(x, m); 1115 1116 x++; 1117 x->rx_buf = &packet->tc.z1; 1118 x->len = 2; 1119 spi_message_add_tail(x, m); 1120 } 1121 1122 ts->msg_count++; 1123 m++; 1124 spi_message_init(m); 1125 m->context = ts; 1126 1127 x++; 1128 packet->read_z2 = READ_Z2(vref); 1129 x->tx_buf = &packet->read_z2; 1130 x->len = 1; 1131 spi_message_add_tail(x, m); 1132 1133 x++; 1134 x->rx_buf = &packet->tc.z2; 1135 x->len = 2; 1136 spi_message_add_tail(x, m); 1137 1138 /* ... maybe discard first sample ... */ 1139 if (pdata->settle_delay_usecs) { 1140 x->delay_usecs = pdata->settle_delay_usecs; 1141 1142 x++; 1143 x->tx_buf = &packet->read_z2; 1144 x->len = 1; 1145 spi_message_add_tail(x, m); 1146 1147 x++; 1148 x->rx_buf = &packet->tc.z2; 1149 x->len = 2; 1150 spi_message_add_tail(x, m); 1151 } 1152 } 1153 1154 /* power down */ 1155 ts->msg_count++; 1156 m++; 1157 spi_message_init(m); 1158 m->context = ts; 1159 1160 if (ts->model == 7845) { 1161 x++; 1162 packet->pwrdown_cmd[0] = PWRDOWN; 1163 packet->pwrdown_cmd[1] = 0; 1164 packet->pwrdown_cmd[2] = 0; 1165 x->tx_buf = &packet->pwrdown_cmd[0]; 1166 x->len = 3; 1167 } else { 1168 x++; 1169 packet->pwrdown = PWRDOWN; 1170 x->tx_buf = &packet->pwrdown; 1171 x->len = 1; 1172 spi_message_add_tail(x, m); 1173 1174 x++; 1175 x->rx_buf = &packet->dummy; 1176 x->len = 2; 1177 } 1178 1179 CS_CHANGE(*x); 1180 spi_message_add_tail(x, m); 1181 } 1182 1183 static int __devinit ads7846_probe(struct spi_device *spi) 1184 { 1185 struct ads7846 *ts; 1186 struct ads7846_packet *packet; 1187 struct input_dev *input_dev; 1188 struct ads7846_platform_data *pdata = spi->dev.platform_data; 1189 unsigned long irq_flags; 1190 int err; 1191 1192 if (!spi->irq) { 1193 dev_dbg(&spi->dev, "no IRQ?\n"); 1194 return -ENODEV; 1195 } 1196 1197 if (!pdata) { 1198 dev_dbg(&spi->dev, "no platform data?\n"); 1199 return -ENODEV; 1200 } 1201 1202 /* don't exceed max specified sample rate */ 1203 if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { 1204 dev_dbg(&spi->dev, "f(sample) %d KHz?\n", 1205 (spi->max_speed_hz/SAMPLE_BITS)/1000); 1206 return -EINVAL; 1207 } 1208 1209 /* We'd set TX word size 8 bits and RX word size to 13 bits ... except 1210 * that even if the hardware can do that, the SPI controller driver 1211 * may not. So we stick to very-portable 8 bit words, both RX and TX. 1212 */ 1213 spi->bits_per_word = 8; 1214 spi->mode = SPI_MODE_0; 1215 err = spi_setup(spi); 1216 if (err < 0) 1217 return err; 1218 1219 ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL); 1220 packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL); 1221 input_dev = input_allocate_device(); 1222 if (!ts || !packet || !input_dev) { 1223 err = -ENOMEM; 1224 goto err_free_mem; 1225 } 1226 1227 dev_set_drvdata(&spi->dev, ts); 1228 1229 ts->packet = packet; 1230 ts->spi = spi; 1231 ts->input = input_dev; 1232 ts->vref_mv = pdata->vref_mv; 1233 ts->swap_xy = pdata->swap_xy; 1234 1235 mutex_init(&ts->lock); 1236 init_waitqueue_head(&ts->wait); 1237 1238 ts->model = pdata->model ? : 7846; 1239 ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; 1240 ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; 1241 ts->pressure_max = pdata->pressure_max ? : ~0; 1242 1243 if (pdata->filter != NULL) { 1244 if (pdata->filter_init != NULL) { 1245 err = pdata->filter_init(pdata, &ts->filter_data); 1246 if (err < 0) 1247 goto err_free_mem; 1248 } 1249 ts->filter = pdata->filter; 1250 ts->filter_cleanup = pdata->filter_cleanup; 1251 } else if (pdata->debounce_max) { 1252 ts->debounce_max = pdata->debounce_max; 1253 if (ts->debounce_max < 2) 1254 ts->debounce_max = 2; 1255 ts->debounce_tol = pdata->debounce_tol; 1256 ts->debounce_rep = pdata->debounce_rep; 1257 ts->filter = ads7846_debounce_filter; 1258 ts->filter_data = ts; 1259 } else { 1260 ts->filter = ads7846_no_filter; 1261 } 1262 1263 err = ads7846_setup_pendown(spi, ts); 1264 if (err) 1265 goto err_cleanup_filter; 1266 1267 if (pdata->penirq_recheck_delay_usecs) 1268 ts->penirq_recheck_delay_usecs = 1269 pdata->penirq_recheck_delay_usecs; 1270 1271 ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync; 1272 1273 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev)); 1274 snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model); 1275 1276 input_dev->name = ts->name; 1277 input_dev->phys = ts->phys; 1278 input_dev->dev.parent = &spi->dev; 1279 1280 input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); 1281 input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); 1282 input_set_abs_params(input_dev, ABS_X, 1283 pdata->x_min ? : 0, 1284 pdata->x_max ? : MAX_12BIT, 1285 0, 0); 1286 input_set_abs_params(input_dev, ABS_Y, 1287 pdata->y_min ? : 0, 1288 pdata->y_max ? : MAX_12BIT, 1289 0, 0); 1290 input_set_abs_params(input_dev, ABS_PRESSURE, 1291 pdata->pressure_min, pdata->pressure_max, 0, 0); 1292 1293 ads7846_setup_spi_msg(ts, pdata); 1294 1295 ts->reg = regulator_get(&spi->dev, "vcc"); 1296 if (IS_ERR(ts->reg)) { 1297 err = PTR_ERR(ts->reg); 1298 dev_err(&spi->dev, "unable to get regulator: %d\n", err); 1299 goto err_free_gpio; 1300 } 1301 1302 err = regulator_enable(ts->reg); 1303 if (err) { 1304 dev_err(&spi->dev, "unable to enable regulator: %d\n", err); 1305 goto err_put_regulator; 1306 } 1307 1308 irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING; 1309 irq_flags |= IRQF_ONESHOT; 1310 1311 err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq, 1312 irq_flags, spi->dev.driver->name, ts); 1313 if (err && !pdata->irq_flags) { 1314 dev_info(&spi->dev, 1315 "trying pin change workaround on irq %d\n", spi->irq); 1316 irq_flags |= IRQF_TRIGGER_RISING; 1317 err = request_threaded_irq(spi->irq, 1318 ads7846_hard_irq, ads7846_irq, 1319 irq_flags, spi->dev.driver->name, ts); 1320 } 1321 1322 if (err) { 1323 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq); 1324 goto err_disable_regulator; 1325 } 1326 1327 err = ads784x_hwmon_register(spi, ts); 1328 if (err) 1329 goto err_free_irq; 1330 1331 dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq); 1332 1333 /* 1334 * Take a first sample, leaving nPENIRQ active and vREF off; avoid 1335 * the touchscreen, in case it's not connected. 1336 */ 1337 if (ts->model == 7845) 1338 ads7845_read12_ser(&spi->dev, PWRDOWN); 1339 else 1340 (void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux)); 1341 1342 err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group); 1343 if (err) 1344 goto err_remove_hwmon; 1345 1346 err = input_register_device(input_dev); 1347 if (err) 1348 goto err_remove_attr_group; 1349 1350 device_init_wakeup(&spi->dev, pdata->wakeup); 1351 1352 return 0; 1353 1354 err_remove_attr_group: 1355 sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group); 1356 err_remove_hwmon: 1357 ads784x_hwmon_unregister(spi, ts); 1358 err_free_irq: 1359 free_irq(spi->irq, ts); 1360 err_disable_regulator: 1361 regulator_disable(ts->reg); 1362 err_put_regulator: 1363 regulator_put(ts->reg); 1364 err_free_gpio: 1365 if (!ts->get_pendown_state) 1366 gpio_free(ts->gpio_pendown); 1367 err_cleanup_filter: 1368 if (ts->filter_cleanup) 1369 ts->filter_cleanup(ts->filter_data); 1370 err_free_mem: 1371 input_free_device(input_dev); 1372 kfree(packet); 1373 kfree(ts); 1374 return err; 1375 } 1376 1377 static int __devexit ads7846_remove(struct spi_device *spi) 1378 { 1379 struct ads7846 *ts = dev_get_drvdata(&spi->dev); 1380 1381 device_init_wakeup(&spi->dev, false); 1382 1383 sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group); 1384 1385 ads7846_disable(ts); 1386 free_irq(ts->spi->irq, ts); 1387 1388 input_unregister_device(ts->input); 1389 1390 ads784x_hwmon_unregister(spi, ts); 1391 1392 regulator_disable(ts->reg); 1393 regulator_put(ts->reg); 1394 1395 if (!ts->get_pendown_state) { 1396 /* 1397 * If we are not using specialized pendown method we must 1398 * have been relying on gpio we set up ourselves. 1399 */ 1400 gpio_free(ts->gpio_pendown); 1401 } 1402 1403 if (ts->filter_cleanup) 1404 ts->filter_cleanup(ts->filter_data); 1405 1406 kfree(ts->packet); 1407 kfree(ts); 1408 1409 dev_dbg(&spi->dev, "unregistered touchscreen\n"); 1410 1411 return 0; 1412 } 1413 1414 static struct spi_driver ads7846_driver = { 1415 .driver = { 1416 .name = "ads7846", 1417 .bus = &spi_bus_type, 1418 .owner = THIS_MODULE, 1419 .pm = &ads7846_pm, 1420 }, 1421 .probe = ads7846_probe, 1422 .remove = __devexit_p(ads7846_remove), 1423 }; 1424 1425 static int __init ads7846_init(void) 1426 { 1427 return spi_register_driver(&ads7846_driver); 1428 } 1429 module_init(ads7846_init); 1430 1431 static void __exit ads7846_exit(void) 1432 { 1433 spi_unregister_driver(&ads7846_driver); 1434 } 1435 module_exit(ads7846_exit); 1436 1437 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver"); 1438 MODULE_LICENSE("GPL"); 1439 MODULE_ALIAS("spi:ads7846"); 1440