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 <linux/module.h> 35 #include <asm/irq.h> 36 37 /* 38 * This code has been heavily tested on a Nokia 770, and lightly 39 * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz). 40 * TSC2046 is just newer ads7846 silicon. 41 * Support for ads7843 tested on Atmel at91sam926x-EK. 42 * Support for ads7845 has only been stubbed in. 43 * Support for Analog Devices AD7873 and AD7843 tested. 44 * 45 * IRQ handling needs a workaround because of a shortcoming in handling 46 * edge triggered IRQs on some platforms like the OMAP1/2. These 47 * platforms don't handle the ARM lazy IRQ disabling properly, thus we 48 * have to maintain our own SW IRQ disabled status. This should be 49 * removed as soon as the affected platform's IRQ handling is fixed. 50 * 51 * App note sbaa036 talks in more detail about accurate sampling... 52 * that ought to help in situations like LCDs inducing noise (which 53 * can also be helped by using synch signals) and more generally. 54 * This driver tries to utilize the measures described in the app 55 * note. The strength of filtering can be set in the board-* specific 56 * files. 57 */ 58 59 #define TS_POLL_DELAY 1 /* ms delay before the first sample */ 60 #define TS_POLL_PERIOD 5 /* ms delay between samples */ 61 62 /* this driver doesn't aim at the peak continuous sample rate */ 63 #define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */) 64 65 struct ts_event { 66 /* 67 * For portability, we can't read 12 bit values using SPI (which 68 * would make the controller deliver them as native byte order 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 bool ignore; 76 u8 x_buf[3]; 77 u8 y_buf[3]; 78 }; 79 80 /* 81 * We allocate this separately to avoid cache line sharing issues when 82 * driver is used with DMA-based SPI controllers (like atmel_spi) on 83 * systems where main memory is not DMA-coherent (most non-x86 boards). 84 */ 85 struct ads7846_packet { 86 u8 read_x, read_y, read_z1, read_z2, pwrdown; 87 u16 dummy; /* for the pwrdown read */ 88 struct ts_event tc; 89 /* for ads7845 with mpc5121 psc spi we use 3-byte buffers */ 90 u8 read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3]; 91 }; 92 93 struct ads7846 { 94 struct input_dev *input; 95 char phys[32]; 96 char name[32]; 97 98 struct spi_device *spi; 99 struct regulator *reg; 100 101 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE) 102 struct attribute_group *attr_group; 103 struct device *hwmon; 104 #endif 105 106 u16 model; 107 u16 vref_mv; 108 u16 vref_delay_usecs; 109 u16 x_plate_ohms; 110 u16 pressure_max; 111 112 bool swap_xy; 113 bool use_internal; 114 115 struct ads7846_packet *packet; 116 117 struct spi_transfer xfer[18]; 118 struct spi_message msg[5]; 119 int msg_count; 120 wait_queue_head_t wait; 121 122 bool pendown; 123 124 int read_cnt; 125 int read_rep; 126 int last_read; 127 128 u16 debounce_max; 129 u16 debounce_tol; 130 u16 debounce_rep; 131 132 u16 penirq_recheck_delay_usecs; 133 134 struct mutex lock; 135 bool stopped; /* P: lock */ 136 bool disabled; /* P: lock */ 137 bool suspended; /* P: lock */ 138 139 int (*filter)(void *data, int data_idx, int *val); 140 void *filter_data; 141 void (*filter_cleanup)(void *data); 142 int (*get_pendown_state)(void); 143 int gpio_pendown; 144 145 void (*wait_for_sync)(void); 146 }; 147 148 /* leave chip selected when we're done, for quicker re-select? */ 149 #if 0 150 #define CS_CHANGE(xfer) ((xfer).cs_change = 1) 151 #else 152 #define CS_CHANGE(xfer) ((xfer).cs_change = 0) 153 #endif 154 155 /*--------------------------------------------------------------------------*/ 156 157 /* The ADS7846 has touchscreen and other sensors. 158 * Earlier ads784x chips are somewhat compatible. 159 */ 160 #define ADS_START (1 << 7) 161 #define ADS_A2A1A0_d_y (1 << 4) /* differential */ 162 #define ADS_A2A1A0_d_z1 (3 << 4) /* differential */ 163 #define ADS_A2A1A0_d_z2 (4 << 4) /* differential */ 164 #define ADS_A2A1A0_d_x (5 << 4) /* differential */ 165 #define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */ 166 #define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */ 167 #define ADS_A2A1A0_vaux (6 << 4) /* non-differential */ 168 #define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */ 169 #define ADS_8_BIT (1 << 3) 170 #define ADS_12_BIT (0 << 3) 171 #define ADS_SER (1 << 2) /* non-differential */ 172 #define ADS_DFR (0 << 2) /* differential */ 173 #define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */ 174 #define ADS_PD10_ADC_ON (1 << 0) /* ADC on */ 175 #define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */ 176 #define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */ 177 178 #define MAX_12BIT ((1<<12)-1) 179 180 /* leave ADC powered up (disables penirq) between differential samples */ 181 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \ 182 | ADS_12_BIT | ADS_DFR | \ 183 (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0)) 184 185 #define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref)) 186 #define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref)) 187 #define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref)) 188 189 #define READ_X(vref) (READ_12BIT_DFR(x, 1, vref)) 190 #define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */ 191 192 /* single-ended samples need to first power up reference voltage; 193 * we leave both ADC and VREF powered 194 */ 195 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \ 196 | ADS_12_BIT | ADS_SER) 197 198 #define REF_ON (READ_12BIT_DFR(x, 1, 1)) 199 #define REF_OFF (READ_12BIT_DFR(y, 0, 0)) 200 201 /* Must be called with ts->lock held */ 202 static void ads7846_stop(struct ads7846 *ts) 203 { 204 if (!ts->disabled && !ts->suspended) { 205 /* Signal IRQ thread to stop polling and disable the handler. */ 206 ts->stopped = true; 207 mb(); 208 wake_up(&ts->wait); 209 disable_irq(ts->spi->irq); 210 } 211 } 212 213 /* Must be called with ts->lock held */ 214 static void ads7846_restart(struct ads7846 *ts) 215 { 216 if (!ts->disabled && !ts->suspended) { 217 /* Tell IRQ thread that it may poll the device. */ 218 ts->stopped = false; 219 mb(); 220 enable_irq(ts->spi->irq); 221 } 222 } 223 224 /* Must be called with ts->lock held */ 225 static void __ads7846_disable(struct ads7846 *ts) 226 { 227 ads7846_stop(ts); 228 regulator_disable(ts->reg); 229 230 /* 231 * We know the chip's in low power mode since we always 232 * leave it that way after every request 233 */ 234 } 235 236 /* Must be called with ts->lock held */ 237 static void __ads7846_enable(struct ads7846 *ts) 238 { 239 regulator_enable(ts->reg); 240 ads7846_restart(ts); 241 } 242 243 static void ads7846_disable(struct ads7846 *ts) 244 { 245 mutex_lock(&ts->lock); 246 247 if (!ts->disabled) { 248 249 if (!ts->suspended) 250 __ads7846_disable(ts); 251 252 ts->disabled = true; 253 } 254 255 mutex_unlock(&ts->lock); 256 } 257 258 static void ads7846_enable(struct ads7846 *ts) 259 { 260 mutex_lock(&ts->lock); 261 262 if (ts->disabled) { 263 264 ts->disabled = false; 265 266 if (!ts->suspended) 267 __ads7846_enable(ts); 268 } 269 270 mutex_unlock(&ts->lock); 271 } 272 273 /*--------------------------------------------------------------------------*/ 274 275 /* 276 * Non-touchscreen sensors only use single-ended conversions. 277 * The range is GND..vREF. The ads7843 and ads7835 must use external vREF; 278 * ads7846 lets that pin be unconnected, to use internal vREF. 279 */ 280 281 struct ser_req { 282 u8 ref_on; 283 u8 command; 284 u8 ref_off; 285 u16 scratch; 286 struct spi_message msg; 287 struct spi_transfer xfer[6]; 288 /* 289 * DMA (thus cache coherency maintenance) requires the 290 * transfer buffers to live in their own cache lines. 291 */ 292 __be16 sample ____cacheline_aligned; 293 }; 294 295 struct ads7845_ser_req { 296 u8 command[3]; 297 struct spi_message msg; 298 struct spi_transfer xfer[2]; 299 /* 300 * DMA (thus cache coherency maintenance) requires the 301 * transfer buffers to live in their own cache lines. 302 */ 303 u8 sample[3] ____cacheline_aligned; 304 }; 305 306 static int ads7846_read12_ser(struct device *dev, unsigned command) 307 { 308 struct spi_device *spi = to_spi_device(dev); 309 struct ads7846 *ts = dev_get_drvdata(dev); 310 struct ser_req *req; 311 int status; 312 313 req = kzalloc(sizeof *req, GFP_KERNEL); 314 if (!req) 315 return -ENOMEM; 316 317 spi_message_init(&req->msg); 318 319 /* maybe turn on internal vREF, and let it settle */ 320 if (ts->use_internal) { 321 req->ref_on = REF_ON; 322 req->xfer[0].tx_buf = &req->ref_on; 323 req->xfer[0].len = 1; 324 spi_message_add_tail(&req->xfer[0], &req->msg); 325 326 req->xfer[1].rx_buf = &req->scratch; 327 req->xfer[1].len = 2; 328 329 /* for 1uF, settle for 800 usec; no cap, 100 usec. */ 330 req->xfer[1].delay_usecs = ts->vref_delay_usecs; 331 spi_message_add_tail(&req->xfer[1], &req->msg); 332 333 /* Enable reference voltage */ 334 command |= ADS_PD10_REF_ON; 335 } 336 337 /* Enable ADC in every case */ 338 command |= ADS_PD10_ADC_ON; 339 340 /* take sample */ 341 req->command = (u8) command; 342 req->xfer[2].tx_buf = &req->command; 343 req->xfer[2].len = 1; 344 spi_message_add_tail(&req->xfer[2], &req->msg); 345 346 req->xfer[3].rx_buf = &req->sample; 347 req->xfer[3].len = 2; 348 spi_message_add_tail(&req->xfer[3], &req->msg); 349 350 /* REVISIT: take a few more samples, and compare ... */ 351 352 /* converter in low power mode & enable PENIRQ */ 353 req->ref_off = PWRDOWN; 354 req->xfer[4].tx_buf = &req->ref_off; 355 req->xfer[4].len = 1; 356 spi_message_add_tail(&req->xfer[4], &req->msg); 357 358 req->xfer[5].rx_buf = &req->scratch; 359 req->xfer[5].len = 2; 360 CS_CHANGE(req->xfer[5]); 361 spi_message_add_tail(&req->xfer[5], &req->msg); 362 363 mutex_lock(&ts->lock); 364 ads7846_stop(ts); 365 status = spi_sync(spi, &req->msg); 366 ads7846_restart(ts); 367 mutex_unlock(&ts->lock); 368 369 if (status == 0) { 370 /* on-wire is a must-ignore bit, a BE12 value, then padding */ 371 status = be16_to_cpu(req->sample); 372 status = status >> 3; 373 status &= 0x0fff; 374 } 375 376 kfree(req); 377 return status; 378 } 379 380 static int ads7845_read12_ser(struct device *dev, unsigned command) 381 { 382 struct spi_device *spi = to_spi_device(dev); 383 struct ads7846 *ts = dev_get_drvdata(dev); 384 struct ads7845_ser_req *req; 385 int status; 386 387 req = kzalloc(sizeof *req, GFP_KERNEL); 388 if (!req) 389 return -ENOMEM; 390 391 spi_message_init(&req->msg); 392 393 req->command[0] = (u8) command; 394 req->xfer[0].tx_buf = req->command; 395 req->xfer[0].rx_buf = req->sample; 396 req->xfer[0].len = 3; 397 spi_message_add_tail(&req->xfer[0], &req->msg); 398 399 mutex_lock(&ts->lock); 400 ads7846_stop(ts); 401 status = spi_sync(spi, &req->msg); 402 ads7846_restart(ts); 403 mutex_unlock(&ts->lock); 404 405 if (status == 0) { 406 /* BE12 value, then padding */ 407 status = be16_to_cpu(*((u16 *)&req->sample[1])); 408 status = status >> 3; 409 status &= 0x0fff; 410 } 411 412 kfree(req); 413 return status; 414 } 415 416 #if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE) 417 418 #define SHOW(name, var, adjust) static ssize_t \ 419 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \ 420 { \ 421 struct ads7846 *ts = dev_get_drvdata(dev); \ 422 ssize_t v = ads7846_read12_ser(dev, \ 423 READ_12BIT_SER(var)); \ 424 if (v < 0) \ 425 return v; \ 426 return sprintf(buf, "%u\n", adjust(ts, v)); \ 427 } \ 428 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL); 429 430 431 /* Sysfs conventions report temperatures in millidegrees Celsius. 432 * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high 433 * accuracy scheme without calibration data. For now we won't try either; 434 * userspace sees raw sensor values, and must scale/calibrate appropriately. 435 */ 436 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v) 437 { 438 return v; 439 } 440 441 SHOW(temp0, temp0, null_adjust) /* temp1_input */ 442 SHOW(temp1, temp1, null_adjust) /* temp2_input */ 443 444 445 /* sysfs conventions report voltages in millivolts. We can convert voltages 446 * if we know vREF. userspace may need to scale vAUX to match the board's 447 * external resistors; we assume that vBATT only uses the internal ones. 448 */ 449 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v) 450 { 451 unsigned retval = v; 452 453 /* external resistors may scale vAUX into 0..vREF */ 454 retval *= ts->vref_mv; 455 retval = retval >> 12; 456 457 return retval; 458 } 459 460 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v) 461 { 462 unsigned retval = vaux_adjust(ts, v); 463 464 /* ads7846 has a resistor ladder to scale this signal down */ 465 if (ts->model == 7846) 466 retval *= 4; 467 468 return retval; 469 } 470 471 SHOW(in0_input, vaux, vaux_adjust) 472 SHOW(in1_input, vbatt, vbatt_adjust) 473 474 static struct attribute *ads7846_attributes[] = { 475 &dev_attr_temp0.attr, 476 &dev_attr_temp1.attr, 477 &dev_attr_in0_input.attr, 478 &dev_attr_in1_input.attr, 479 NULL, 480 }; 481 482 static struct attribute_group ads7846_attr_group = { 483 .attrs = ads7846_attributes, 484 }; 485 486 static struct attribute *ads7843_attributes[] = { 487 &dev_attr_in0_input.attr, 488 &dev_attr_in1_input.attr, 489 NULL, 490 }; 491 492 static struct attribute_group ads7843_attr_group = { 493 .attrs = ads7843_attributes, 494 }; 495 496 static struct attribute *ads7845_attributes[] = { 497 &dev_attr_in0_input.attr, 498 NULL, 499 }; 500 501 static struct attribute_group ads7845_attr_group = { 502 .attrs = ads7845_attributes, 503 }; 504 505 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts) 506 { 507 struct device *hwmon; 508 int err; 509 510 /* hwmon sensors need a reference voltage */ 511 switch (ts->model) { 512 case 7846: 513 if (!ts->vref_mv) { 514 dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n"); 515 ts->vref_mv = 2500; 516 ts->use_internal = true; 517 } 518 break; 519 case 7845: 520 case 7843: 521 if (!ts->vref_mv) { 522 dev_warn(&spi->dev, 523 "external vREF for ADS%d not specified\n", 524 ts->model); 525 return 0; 526 } 527 break; 528 } 529 530 /* different chips have different sensor groups */ 531 switch (ts->model) { 532 case 7846: 533 ts->attr_group = &ads7846_attr_group; 534 break; 535 case 7845: 536 ts->attr_group = &ads7845_attr_group; 537 break; 538 case 7843: 539 ts->attr_group = &ads7843_attr_group; 540 break; 541 default: 542 dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model); 543 return 0; 544 } 545 546 err = sysfs_create_group(&spi->dev.kobj, ts->attr_group); 547 if (err) 548 return err; 549 550 hwmon = hwmon_device_register(&spi->dev); 551 if (IS_ERR(hwmon)) { 552 sysfs_remove_group(&spi->dev.kobj, ts->attr_group); 553 return PTR_ERR(hwmon); 554 } 555 556 ts->hwmon = hwmon; 557 return 0; 558 } 559 560 static void ads784x_hwmon_unregister(struct spi_device *spi, 561 struct ads7846 *ts) 562 { 563 if (ts->hwmon) { 564 sysfs_remove_group(&spi->dev.kobj, ts->attr_group); 565 hwmon_device_unregister(ts->hwmon); 566 } 567 } 568 569 #else 570 static inline int ads784x_hwmon_register(struct spi_device *spi, 571 struct ads7846 *ts) 572 { 573 return 0; 574 } 575 576 static inline void ads784x_hwmon_unregister(struct spi_device *spi, 577 struct ads7846 *ts) 578 { 579 } 580 #endif 581 582 static ssize_t ads7846_pen_down_show(struct device *dev, 583 struct device_attribute *attr, char *buf) 584 { 585 struct ads7846 *ts = dev_get_drvdata(dev); 586 587 return sprintf(buf, "%u\n", ts->pendown); 588 } 589 590 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL); 591 592 static ssize_t ads7846_disable_show(struct device *dev, 593 struct device_attribute *attr, char *buf) 594 { 595 struct ads7846 *ts = dev_get_drvdata(dev); 596 597 return sprintf(buf, "%u\n", ts->disabled); 598 } 599 600 static ssize_t ads7846_disable_store(struct device *dev, 601 struct device_attribute *attr, 602 const char *buf, size_t count) 603 { 604 struct ads7846 *ts = dev_get_drvdata(dev); 605 unsigned int i; 606 int err; 607 608 err = kstrtouint(buf, 10, &i); 609 if (err) 610 return err; 611 612 if (i) 613 ads7846_disable(ts); 614 else 615 ads7846_enable(ts); 616 617 return count; 618 } 619 620 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store); 621 622 static struct attribute *ads784x_attributes[] = { 623 &dev_attr_pen_down.attr, 624 &dev_attr_disable.attr, 625 NULL, 626 }; 627 628 static struct attribute_group ads784x_attr_group = { 629 .attrs = ads784x_attributes, 630 }; 631 632 /*--------------------------------------------------------------------------*/ 633 634 static int get_pendown_state(struct ads7846 *ts) 635 { 636 if (ts->get_pendown_state) 637 return ts->get_pendown_state(); 638 639 return !gpio_get_value(ts->gpio_pendown); 640 } 641 642 static void null_wait_for_sync(void) 643 { 644 } 645 646 static int ads7846_debounce_filter(void *ads, int data_idx, int *val) 647 { 648 struct ads7846 *ts = ads; 649 650 if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) { 651 /* Start over collecting consistent readings. */ 652 ts->read_rep = 0; 653 /* 654 * Repeat it, if this was the first read or the read 655 * wasn't consistent enough. 656 */ 657 if (ts->read_cnt < ts->debounce_max) { 658 ts->last_read = *val; 659 ts->read_cnt++; 660 return ADS7846_FILTER_REPEAT; 661 } else { 662 /* 663 * Maximum number of debouncing reached and still 664 * not enough number of consistent readings. Abort 665 * the whole sample, repeat it in the next sampling 666 * period. 667 */ 668 ts->read_cnt = 0; 669 return ADS7846_FILTER_IGNORE; 670 } 671 } else { 672 if (++ts->read_rep > ts->debounce_rep) { 673 /* 674 * Got a good reading for this coordinate, 675 * go for the next one. 676 */ 677 ts->read_cnt = 0; 678 ts->read_rep = 0; 679 return ADS7846_FILTER_OK; 680 } else { 681 /* Read more values that are consistent. */ 682 ts->read_cnt++; 683 return ADS7846_FILTER_REPEAT; 684 } 685 } 686 } 687 688 static int ads7846_no_filter(void *ads, int data_idx, int *val) 689 { 690 return ADS7846_FILTER_OK; 691 } 692 693 static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m) 694 { 695 struct spi_transfer *t = 696 list_entry(m->transfers.prev, struct spi_transfer, transfer_list); 697 698 if (ts->model == 7845) { 699 return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3; 700 } else { 701 /* 702 * adjust: on-wire is a must-ignore bit, a BE12 value, then 703 * padding; built from two 8 bit values written msb-first. 704 */ 705 return be16_to_cpup((__be16 *)t->rx_buf) >> 3; 706 } 707 } 708 709 static void ads7846_update_value(struct spi_message *m, int val) 710 { 711 struct spi_transfer *t = 712 list_entry(m->transfers.prev, struct spi_transfer, transfer_list); 713 714 *(u16 *)t->rx_buf = val; 715 } 716 717 static void ads7846_read_state(struct ads7846 *ts) 718 { 719 struct ads7846_packet *packet = ts->packet; 720 struct spi_message *m; 721 int msg_idx = 0; 722 int val; 723 int action; 724 int error; 725 726 while (msg_idx < ts->msg_count) { 727 728 ts->wait_for_sync(); 729 730 m = &ts->msg[msg_idx]; 731 error = spi_sync(ts->spi, m); 732 if (error) { 733 dev_err(&ts->spi->dev, "spi_async --> %d\n", error); 734 packet->tc.ignore = true; 735 return; 736 } 737 738 /* 739 * Last message is power down request, no need to convert 740 * or filter the value. 741 */ 742 if (msg_idx < ts->msg_count - 1) { 743 744 val = ads7846_get_value(ts, m); 745 746 action = ts->filter(ts->filter_data, msg_idx, &val); 747 switch (action) { 748 case ADS7846_FILTER_REPEAT: 749 continue; 750 751 case ADS7846_FILTER_IGNORE: 752 packet->tc.ignore = true; 753 msg_idx = ts->msg_count - 1; 754 continue; 755 756 case ADS7846_FILTER_OK: 757 ads7846_update_value(m, val); 758 packet->tc.ignore = false; 759 msg_idx++; 760 break; 761 762 default: 763 BUG(); 764 } 765 } else { 766 msg_idx++; 767 } 768 } 769 } 770 771 static void ads7846_report_state(struct ads7846 *ts) 772 { 773 struct ads7846_packet *packet = ts->packet; 774 unsigned int Rt; 775 u16 x, y, z1, z2; 776 777 /* 778 * ads7846_get_value() does in-place conversion (including byte swap) 779 * from on-the-wire format as part of debouncing to get stable 780 * readings. 781 */ 782 if (ts->model == 7845) { 783 x = *(u16 *)packet->tc.x_buf; 784 y = *(u16 *)packet->tc.y_buf; 785 z1 = 0; 786 z2 = 0; 787 } else { 788 x = packet->tc.x; 789 y = packet->tc.y; 790 z1 = packet->tc.z1; 791 z2 = packet->tc.z2; 792 } 793 794 /* range filtering */ 795 if (x == MAX_12BIT) 796 x = 0; 797 798 if (ts->model == 7843) { 799 Rt = ts->pressure_max / 2; 800 } else if (ts->model == 7845) { 801 if (get_pendown_state(ts)) 802 Rt = ts->pressure_max / 2; 803 else 804 Rt = 0; 805 dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt); 806 } else if (likely(x && z1)) { 807 /* compute touch pressure resistance using equation #2 */ 808 Rt = z2; 809 Rt -= z1; 810 Rt *= x; 811 Rt *= ts->x_plate_ohms; 812 Rt /= z1; 813 Rt = (Rt + 2047) >> 12; 814 } else { 815 Rt = 0; 816 } 817 818 /* 819 * Sample found inconsistent by debouncing or pressure is beyond 820 * the maximum. Don't report it to user space, repeat at least 821 * once more the measurement 822 */ 823 if (packet->tc.ignore || Rt > ts->pressure_max) { 824 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n", 825 packet->tc.ignore, Rt); 826 return; 827 } 828 829 /* 830 * Maybe check the pendown state before reporting. This discards 831 * false readings when the pen is lifted. 832 */ 833 if (ts->penirq_recheck_delay_usecs) { 834 udelay(ts->penirq_recheck_delay_usecs); 835 if (!get_pendown_state(ts)) 836 Rt = 0; 837 } 838 839 /* 840 * NOTE: We can't rely on the pressure to determine the pen down 841 * state, even this controller has a pressure sensor. The pressure 842 * value can fluctuate for quite a while after lifting the pen and 843 * in some cases may not even settle at the expected value. 844 * 845 * The only safe way to check for the pen up condition is in the 846 * timer by reading the pen signal state (it's a GPIO _and_ IRQ). 847 */ 848 if (Rt) { 849 struct input_dev *input = ts->input; 850 851 if (ts->swap_xy) 852 swap(x, y); 853 854 if (!ts->pendown) { 855 input_report_key(input, BTN_TOUCH, 1); 856 ts->pendown = true; 857 dev_vdbg(&ts->spi->dev, "DOWN\n"); 858 } 859 860 input_report_abs(input, ABS_X, x); 861 input_report_abs(input, ABS_Y, y); 862 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt); 863 864 input_sync(input); 865 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt); 866 } 867 } 868 869 static irqreturn_t ads7846_hard_irq(int irq, void *handle) 870 { 871 struct ads7846 *ts = handle; 872 873 return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED; 874 } 875 876 877 static irqreturn_t ads7846_irq(int irq, void *handle) 878 { 879 struct ads7846 *ts = handle; 880 881 /* Start with a small delay before checking pendown state */ 882 msleep(TS_POLL_DELAY); 883 884 while (!ts->stopped && get_pendown_state(ts)) { 885 886 /* pen is down, continue with the measurement */ 887 ads7846_read_state(ts); 888 889 if (!ts->stopped) 890 ads7846_report_state(ts); 891 892 wait_event_timeout(ts->wait, ts->stopped, 893 msecs_to_jiffies(TS_POLL_PERIOD)); 894 } 895 896 if (ts->pendown) { 897 struct input_dev *input = ts->input; 898 899 input_report_key(input, BTN_TOUCH, 0); 900 input_report_abs(input, ABS_PRESSURE, 0); 901 input_sync(input); 902 903 ts->pendown = false; 904 dev_vdbg(&ts->spi->dev, "UP\n"); 905 } 906 907 return IRQ_HANDLED; 908 } 909 910 #ifdef CONFIG_PM_SLEEP 911 static int ads7846_suspend(struct device *dev) 912 { 913 struct ads7846 *ts = dev_get_drvdata(dev); 914 915 mutex_lock(&ts->lock); 916 917 if (!ts->suspended) { 918 919 if (!ts->disabled) 920 __ads7846_disable(ts); 921 922 if (device_may_wakeup(&ts->spi->dev)) 923 enable_irq_wake(ts->spi->irq); 924 925 ts->suspended = true; 926 } 927 928 mutex_unlock(&ts->lock); 929 930 return 0; 931 } 932 933 static int ads7846_resume(struct device *dev) 934 { 935 struct ads7846 *ts = dev_get_drvdata(dev); 936 937 mutex_lock(&ts->lock); 938 939 if (ts->suspended) { 940 941 ts->suspended = false; 942 943 if (device_may_wakeup(&ts->spi->dev)) 944 disable_irq_wake(ts->spi->irq); 945 946 if (!ts->disabled) 947 __ads7846_enable(ts); 948 } 949 950 mutex_unlock(&ts->lock); 951 952 return 0; 953 } 954 #endif 955 956 static SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume); 957 958 static int ads7846_setup_pendown(struct spi_device *spi, 959 struct ads7846 *ts) 960 { 961 struct ads7846_platform_data *pdata = spi->dev.platform_data; 962 int err; 963 964 /* 965 * REVISIT when the irq can be triggered active-low, or if for some 966 * reason the touchscreen isn't hooked up, we don't need to access 967 * the pendown state. 968 */ 969 970 if (pdata->get_pendown_state) { 971 ts->get_pendown_state = pdata->get_pendown_state; 972 } else if (gpio_is_valid(pdata->gpio_pendown)) { 973 974 err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN, 975 "ads7846_pendown"); 976 if (err) { 977 dev_err(&spi->dev, 978 "failed to request/setup pendown GPIO%d: %d\n", 979 pdata->gpio_pendown, err); 980 return err; 981 } 982 983 ts->gpio_pendown = pdata->gpio_pendown; 984 985 if (pdata->gpio_pendown_debounce) 986 gpio_set_debounce(pdata->gpio_pendown, 987 pdata->gpio_pendown_debounce); 988 } else { 989 dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n"); 990 return -EINVAL; 991 } 992 993 return 0; 994 } 995 996 /* 997 * Set up the transfers to read touchscreen state; this assumes we 998 * use formula #2 for pressure, not #3. 999 */ 1000 static void ads7846_setup_spi_msg(struct ads7846 *ts, 1001 const struct ads7846_platform_data *pdata) 1002 { 1003 struct spi_message *m = &ts->msg[0]; 1004 struct spi_transfer *x = ts->xfer; 1005 struct ads7846_packet *packet = ts->packet; 1006 int vref = pdata->keep_vref_on; 1007 1008 if (ts->model == 7873) { 1009 /* 1010 * The AD7873 is almost identical to the ADS7846 1011 * keep VREF off during differential/ratiometric 1012 * conversion modes. 1013 */ 1014 ts->model = 7846; 1015 vref = 0; 1016 } 1017 1018 ts->msg_count = 1; 1019 spi_message_init(m); 1020 m->context = ts; 1021 1022 if (ts->model == 7845) { 1023 packet->read_y_cmd[0] = READ_Y(vref); 1024 packet->read_y_cmd[1] = 0; 1025 packet->read_y_cmd[2] = 0; 1026 x->tx_buf = &packet->read_y_cmd[0]; 1027 x->rx_buf = &packet->tc.y_buf[0]; 1028 x->len = 3; 1029 spi_message_add_tail(x, m); 1030 } else { 1031 /* y- still on; turn on only y+ (and ADC) */ 1032 packet->read_y = READ_Y(vref); 1033 x->tx_buf = &packet->read_y; 1034 x->len = 1; 1035 spi_message_add_tail(x, m); 1036 1037 x++; 1038 x->rx_buf = &packet->tc.y; 1039 x->len = 2; 1040 spi_message_add_tail(x, m); 1041 } 1042 1043 /* 1044 * The first sample after switching drivers can be low quality; 1045 * optionally discard it, using a second one after the signals 1046 * have had enough time to stabilize. 1047 */ 1048 if (pdata->settle_delay_usecs) { 1049 x->delay_usecs = pdata->settle_delay_usecs; 1050 1051 x++; 1052 x->tx_buf = &packet->read_y; 1053 x->len = 1; 1054 spi_message_add_tail(x, m); 1055 1056 x++; 1057 x->rx_buf = &packet->tc.y; 1058 x->len = 2; 1059 spi_message_add_tail(x, m); 1060 } 1061 1062 ts->msg_count++; 1063 m++; 1064 spi_message_init(m); 1065 m->context = ts; 1066 1067 if (ts->model == 7845) { 1068 x++; 1069 packet->read_x_cmd[0] = READ_X(vref); 1070 packet->read_x_cmd[1] = 0; 1071 packet->read_x_cmd[2] = 0; 1072 x->tx_buf = &packet->read_x_cmd[0]; 1073 x->rx_buf = &packet->tc.x_buf[0]; 1074 x->len = 3; 1075 spi_message_add_tail(x, m); 1076 } else { 1077 /* turn y- off, x+ on, then leave in lowpower */ 1078 x++; 1079 packet->read_x = READ_X(vref); 1080 x->tx_buf = &packet->read_x; 1081 x->len = 1; 1082 spi_message_add_tail(x, m); 1083 1084 x++; 1085 x->rx_buf = &packet->tc.x; 1086 x->len = 2; 1087 spi_message_add_tail(x, m); 1088 } 1089 1090 /* ... maybe discard first sample ... */ 1091 if (pdata->settle_delay_usecs) { 1092 x->delay_usecs = pdata->settle_delay_usecs; 1093 1094 x++; 1095 x->tx_buf = &packet->read_x; 1096 x->len = 1; 1097 spi_message_add_tail(x, m); 1098 1099 x++; 1100 x->rx_buf = &packet->tc.x; 1101 x->len = 2; 1102 spi_message_add_tail(x, m); 1103 } 1104 1105 /* turn y+ off, x- on; we'll use formula #2 */ 1106 if (ts->model == 7846) { 1107 ts->msg_count++; 1108 m++; 1109 spi_message_init(m); 1110 m->context = ts; 1111 1112 x++; 1113 packet->read_z1 = READ_Z1(vref); 1114 x->tx_buf = &packet->read_z1; 1115 x->len = 1; 1116 spi_message_add_tail(x, m); 1117 1118 x++; 1119 x->rx_buf = &packet->tc.z1; 1120 x->len = 2; 1121 spi_message_add_tail(x, m); 1122 1123 /* ... maybe discard first sample ... */ 1124 if (pdata->settle_delay_usecs) { 1125 x->delay_usecs = pdata->settle_delay_usecs; 1126 1127 x++; 1128 x->tx_buf = &packet->read_z1; 1129 x->len = 1; 1130 spi_message_add_tail(x, m); 1131 1132 x++; 1133 x->rx_buf = &packet->tc.z1; 1134 x->len = 2; 1135 spi_message_add_tail(x, m); 1136 } 1137 1138 ts->msg_count++; 1139 m++; 1140 spi_message_init(m); 1141 m->context = ts; 1142 1143 x++; 1144 packet->read_z2 = READ_Z2(vref); 1145 x->tx_buf = &packet->read_z2; 1146 x->len = 1; 1147 spi_message_add_tail(x, m); 1148 1149 x++; 1150 x->rx_buf = &packet->tc.z2; 1151 x->len = 2; 1152 spi_message_add_tail(x, m); 1153 1154 /* ... maybe discard first sample ... */ 1155 if (pdata->settle_delay_usecs) { 1156 x->delay_usecs = pdata->settle_delay_usecs; 1157 1158 x++; 1159 x->tx_buf = &packet->read_z2; 1160 x->len = 1; 1161 spi_message_add_tail(x, m); 1162 1163 x++; 1164 x->rx_buf = &packet->tc.z2; 1165 x->len = 2; 1166 spi_message_add_tail(x, m); 1167 } 1168 } 1169 1170 /* power down */ 1171 ts->msg_count++; 1172 m++; 1173 spi_message_init(m); 1174 m->context = ts; 1175 1176 if (ts->model == 7845) { 1177 x++; 1178 packet->pwrdown_cmd[0] = PWRDOWN; 1179 packet->pwrdown_cmd[1] = 0; 1180 packet->pwrdown_cmd[2] = 0; 1181 x->tx_buf = &packet->pwrdown_cmd[0]; 1182 x->len = 3; 1183 } else { 1184 x++; 1185 packet->pwrdown = PWRDOWN; 1186 x->tx_buf = &packet->pwrdown; 1187 x->len = 1; 1188 spi_message_add_tail(x, m); 1189 1190 x++; 1191 x->rx_buf = &packet->dummy; 1192 x->len = 2; 1193 } 1194 1195 CS_CHANGE(*x); 1196 spi_message_add_tail(x, m); 1197 } 1198 1199 static int ads7846_probe(struct spi_device *spi) 1200 { 1201 struct ads7846 *ts; 1202 struct ads7846_packet *packet; 1203 struct input_dev *input_dev; 1204 struct ads7846_platform_data *pdata = spi->dev.platform_data; 1205 unsigned long irq_flags; 1206 int err; 1207 1208 if (!spi->irq) { 1209 dev_dbg(&spi->dev, "no IRQ?\n"); 1210 return -ENODEV; 1211 } 1212 1213 if (!pdata) { 1214 dev_dbg(&spi->dev, "no platform data?\n"); 1215 return -ENODEV; 1216 } 1217 1218 /* don't exceed max specified sample rate */ 1219 if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { 1220 dev_dbg(&spi->dev, "f(sample) %d KHz?\n", 1221 (spi->max_speed_hz/SAMPLE_BITS)/1000); 1222 return -EINVAL; 1223 } 1224 1225 /* We'd set TX word size 8 bits and RX word size to 13 bits ... except 1226 * that even if the hardware can do that, the SPI controller driver 1227 * may not. So we stick to very-portable 8 bit words, both RX and TX. 1228 */ 1229 spi->bits_per_word = 8; 1230 spi->mode = SPI_MODE_0; 1231 err = spi_setup(spi); 1232 if (err < 0) 1233 return err; 1234 1235 ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL); 1236 packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL); 1237 input_dev = input_allocate_device(); 1238 if (!ts || !packet || !input_dev) { 1239 err = -ENOMEM; 1240 goto err_free_mem; 1241 } 1242 1243 dev_set_drvdata(&spi->dev, ts); 1244 1245 ts->packet = packet; 1246 ts->spi = spi; 1247 ts->input = input_dev; 1248 ts->vref_mv = pdata->vref_mv; 1249 ts->swap_xy = pdata->swap_xy; 1250 1251 mutex_init(&ts->lock); 1252 init_waitqueue_head(&ts->wait); 1253 1254 ts->model = pdata->model ? : 7846; 1255 ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; 1256 ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; 1257 ts->pressure_max = pdata->pressure_max ? : ~0; 1258 1259 if (pdata->filter != NULL) { 1260 if (pdata->filter_init != NULL) { 1261 err = pdata->filter_init(pdata, &ts->filter_data); 1262 if (err < 0) 1263 goto err_free_mem; 1264 } 1265 ts->filter = pdata->filter; 1266 ts->filter_cleanup = pdata->filter_cleanup; 1267 } else if (pdata->debounce_max) { 1268 ts->debounce_max = pdata->debounce_max; 1269 if (ts->debounce_max < 2) 1270 ts->debounce_max = 2; 1271 ts->debounce_tol = pdata->debounce_tol; 1272 ts->debounce_rep = pdata->debounce_rep; 1273 ts->filter = ads7846_debounce_filter; 1274 ts->filter_data = ts; 1275 } else { 1276 ts->filter = ads7846_no_filter; 1277 } 1278 1279 err = ads7846_setup_pendown(spi, ts); 1280 if (err) 1281 goto err_cleanup_filter; 1282 1283 if (pdata->penirq_recheck_delay_usecs) 1284 ts->penirq_recheck_delay_usecs = 1285 pdata->penirq_recheck_delay_usecs; 1286 1287 ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync; 1288 1289 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev)); 1290 snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model); 1291 1292 input_dev->name = ts->name; 1293 input_dev->phys = ts->phys; 1294 input_dev->dev.parent = &spi->dev; 1295 1296 input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); 1297 input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); 1298 input_set_abs_params(input_dev, ABS_X, 1299 pdata->x_min ? : 0, 1300 pdata->x_max ? : MAX_12BIT, 1301 0, 0); 1302 input_set_abs_params(input_dev, ABS_Y, 1303 pdata->y_min ? : 0, 1304 pdata->y_max ? : MAX_12BIT, 1305 0, 0); 1306 input_set_abs_params(input_dev, ABS_PRESSURE, 1307 pdata->pressure_min, pdata->pressure_max, 0, 0); 1308 1309 ads7846_setup_spi_msg(ts, pdata); 1310 1311 ts->reg = regulator_get(&spi->dev, "vcc"); 1312 if (IS_ERR(ts->reg)) { 1313 err = PTR_ERR(ts->reg); 1314 dev_err(&spi->dev, "unable to get regulator: %d\n", err); 1315 goto err_free_gpio; 1316 } 1317 1318 err = regulator_enable(ts->reg); 1319 if (err) { 1320 dev_err(&spi->dev, "unable to enable regulator: %d\n", err); 1321 goto err_put_regulator; 1322 } 1323 1324 irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING; 1325 irq_flags |= IRQF_ONESHOT; 1326 1327 err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq, 1328 irq_flags, spi->dev.driver->name, ts); 1329 if (err && !pdata->irq_flags) { 1330 dev_info(&spi->dev, 1331 "trying pin change workaround on irq %d\n", spi->irq); 1332 irq_flags |= IRQF_TRIGGER_RISING; 1333 err = request_threaded_irq(spi->irq, 1334 ads7846_hard_irq, ads7846_irq, 1335 irq_flags, spi->dev.driver->name, ts); 1336 } 1337 1338 if (err) { 1339 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq); 1340 goto err_disable_regulator; 1341 } 1342 1343 err = ads784x_hwmon_register(spi, ts); 1344 if (err) 1345 goto err_free_irq; 1346 1347 dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq); 1348 1349 /* 1350 * Take a first sample, leaving nPENIRQ active and vREF off; avoid 1351 * the touchscreen, in case it's not connected. 1352 */ 1353 if (ts->model == 7845) 1354 ads7845_read12_ser(&spi->dev, PWRDOWN); 1355 else 1356 (void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux)); 1357 1358 err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group); 1359 if (err) 1360 goto err_remove_hwmon; 1361 1362 err = input_register_device(input_dev); 1363 if (err) 1364 goto err_remove_attr_group; 1365 1366 device_init_wakeup(&spi->dev, pdata->wakeup); 1367 1368 return 0; 1369 1370 err_remove_attr_group: 1371 sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group); 1372 err_remove_hwmon: 1373 ads784x_hwmon_unregister(spi, ts); 1374 err_free_irq: 1375 free_irq(spi->irq, ts); 1376 err_disable_regulator: 1377 regulator_disable(ts->reg); 1378 err_put_regulator: 1379 regulator_put(ts->reg); 1380 err_free_gpio: 1381 if (!ts->get_pendown_state) 1382 gpio_free(ts->gpio_pendown); 1383 err_cleanup_filter: 1384 if (ts->filter_cleanup) 1385 ts->filter_cleanup(ts->filter_data); 1386 err_free_mem: 1387 input_free_device(input_dev); 1388 kfree(packet); 1389 kfree(ts); 1390 return err; 1391 } 1392 1393 static int __devexit ads7846_remove(struct spi_device *spi) 1394 { 1395 struct ads7846 *ts = dev_get_drvdata(&spi->dev); 1396 1397 device_init_wakeup(&spi->dev, false); 1398 1399 sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group); 1400 1401 ads7846_disable(ts); 1402 free_irq(ts->spi->irq, ts); 1403 1404 input_unregister_device(ts->input); 1405 1406 ads784x_hwmon_unregister(spi, ts); 1407 1408 regulator_disable(ts->reg); 1409 regulator_put(ts->reg); 1410 1411 if (!ts->get_pendown_state) { 1412 /* 1413 * If we are not using specialized pendown method we must 1414 * have been relying on gpio we set up ourselves. 1415 */ 1416 gpio_free(ts->gpio_pendown); 1417 } 1418 1419 if (ts->filter_cleanup) 1420 ts->filter_cleanup(ts->filter_data); 1421 1422 kfree(ts->packet); 1423 kfree(ts); 1424 1425 dev_dbg(&spi->dev, "unregistered touchscreen\n"); 1426 1427 return 0; 1428 } 1429 1430 static struct spi_driver ads7846_driver = { 1431 .driver = { 1432 .name = "ads7846", 1433 .owner = THIS_MODULE, 1434 .pm = &ads7846_pm, 1435 }, 1436 .probe = ads7846_probe, 1437 .remove = ads7846_remove, 1438 }; 1439 1440 module_spi_driver(ads7846_driver); 1441 1442 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver"); 1443 MODULE_LICENSE("GPL"); 1444 MODULE_ALIAS("spi:ads7846"); 1445