1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ADS7846 based touchscreen and sensor driver 4 * 5 * Copyright (c) 2005 David Brownell 6 * Copyright (c) 2006 Nokia Corporation 7 * Various changes: Imre Deak <imre.deak@nokia.com> 8 * 9 * Using code from: 10 * - corgi_ts.c 11 * Copyright (C) 2004-2005 Richard Purdie 12 * - omap_ts.[hc], ads7846.h, ts_osk.c 13 * Copyright (C) 2002 MontaVista Software 14 * Copyright (C) 2004 Texas Instruments 15 * Copyright (C) 2005 Dirk Behme 16 */ 17 #include <linux/types.h> 18 #include <linux/hwmon.h> 19 #include <linux/err.h> 20 #include <linux/sched.h> 21 #include <linux/delay.h> 22 #include <linux/input.h> 23 #include <linux/input/touchscreen.h> 24 #include <linux/interrupt.h> 25 #include <linux/slab.h> 26 #include <linux/pm.h> 27 #include <linux/property.h> 28 #include <linux/gpio/consumer.h> 29 #include <linux/spi/spi.h> 30 #include <linux/spi/ads7846.h> 31 #include <linux/regulator/consumer.h> 32 #include <linux/module.h> 33 #include <asm/unaligned.h> 34 35 /* 36 * This code has been heavily tested on a Nokia 770, and lightly 37 * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz). 38 * TSC2046 is just newer ads7846 silicon. 39 * Support for ads7843 tested on Atmel at91sam926x-EK. 40 * Support for ads7845 has only been stubbed in. 41 * Support for Analog Devices AD7873 and AD7843 tested. 42 * 43 * IRQ handling needs a workaround because of a shortcoming in handling 44 * edge triggered IRQs on some platforms like the OMAP1/2. These 45 * platforms don't handle the ARM lazy IRQ disabling properly, thus we 46 * have to maintain our own SW IRQ disabled status. This should be 47 * removed as soon as the affected platform's IRQ handling is fixed. 48 * 49 * App note sbaa036 talks in more detail about accurate sampling... 50 * that ought to help in situations like LCDs inducing noise (which 51 * can also be helped by using synch signals) and more generally. 52 * This driver tries to utilize the measures described in the app 53 * note. The strength of filtering can be set in the board-* specific 54 * files. 55 */ 56 57 #define TS_POLL_DELAY 1 /* ms delay before the first sample */ 58 #define TS_POLL_PERIOD 5 /* ms delay between samples */ 59 60 /* this driver doesn't aim at the peak continuous sample rate */ 61 #define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */) 62 63 struct ads7846_buf { 64 u8 cmd; 65 __be16 data; 66 } __packed; 67 68 struct ads7846_buf_layout { 69 unsigned int offset; 70 unsigned int count; 71 unsigned int skip; 72 }; 73 74 /* 75 * We allocate this separately to avoid cache line sharing issues when 76 * driver is used with DMA-based SPI controllers (like atmel_spi) on 77 * systems where main memory is not DMA-coherent (most non-x86 boards). 78 */ 79 struct ads7846_packet { 80 unsigned int count; 81 unsigned int count_skip; 82 unsigned int cmds; 83 unsigned int last_cmd_idx; 84 struct ads7846_buf_layout l[5]; 85 struct ads7846_buf *rx; 86 struct ads7846_buf *tx; 87 88 struct ads7846_buf pwrdown_cmd; 89 90 bool ignore; 91 u16 x, y, z1, z2; 92 }; 93 94 struct ads7846 { 95 struct input_dev *input; 96 char phys[32]; 97 char name[32]; 98 99 struct spi_device *spi; 100 struct regulator *reg; 101 102 u16 model; 103 u16 vref_mv; 104 u16 vref_delay_usecs; 105 u16 x_plate_ohms; 106 u16 pressure_max; 107 108 bool swap_xy; 109 bool use_internal; 110 111 struct ads7846_packet *packet; 112 113 struct spi_transfer xfer[18]; 114 struct spi_message msg[5]; 115 int msg_count; 116 wait_queue_head_t wait; 117 118 bool pendown; 119 120 int read_cnt; 121 int read_rep; 122 int last_read; 123 124 u16 debounce_max; 125 u16 debounce_tol; 126 u16 debounce_rep; 127 128 u16 penirq_recheck_delay_usecs; 129 130 struct touchscreen_properties core_prop; 131 132 struct mutex lock; 133 bool stopped; /* P: lock */ 134 bool disabled; /* P: lock */ 135 bool suspended; /* P: lock */ 136 137 int (*filter)(void *data, int data_idx, int *val); 138 void *filter_data; 139 int (*get_pendown_state)(void); 140 struct gpio_desc *gpio_pendown; 141 142 void (*wait_for_sync)(void); 143 }; 144 145 enum ads7846_filter { 146 ADS7846_FILTER_OK, 147 ADS7846_FILTER_REPEAT, 148 ADS7846_FILTER_IGNORE, 149 }; 150 151 /* leave chip selected when we're done, for quicker re-select? */ 152 #if 0 153 #define CS_CHANGE(xfer) ((xfer).cs_change = 1) 154 #else 155 #define CS_CHANGE(xfer) ((xfer).cs_change = 0) 156 #endif 157 158 /*--------------------------------------------------------------------------*/ 159 160 /* The ADS7846 has touchscreen and other sensors. 161 * Earlier ads784x chips are somewhat compatible. 162 */ 163 #define ADS_START (1 << 7) 164 #define ADS_A2A1A0_d_y (1 << 4) /* differential */ 165 #define ADS_A2A1A0_d_z1 (3 << 4) /* differential */ 166 #define ADS_A2A1A0_d_z2 (4 << 4) /* differential */ 167 #define ADS_A2A1A0_d_x (5 << 4) /* differential */ 168 #define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */ 169 #define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */ 170 #define ADS_A2A1A0_vaux (6 << 4) /* non-differential */ 171 #define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */ 172 #define ADS_8_BIT (1 << 3) 173 #define ADS_12_BIT (0 << 3) 174 #define ADS_SER (1 << 2) /* non-differential */ 175 #define ADS_DFR (0 << 2) /* differential */ 176 #define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */ 177 #define ADS_PD10_ADC_ON (1 << 0) /* ADC on */ 178 #define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */ 179 #define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */ 180 181 #define MAX_12BIT ((1<<12)-1) 182 183 /* leave ADC powered up (disables penirq) between differential samples */ 184 #define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \ 185 | ADS_12_BIT | ADS_DFR | \ 186 (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0)) 187 188 #define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref)) 189 #define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref)) 190 #define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref)) 191 #define READ_X(vref) (READ_12BIT_DFR(x, 1, vref)) 192 #define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */ 193 194 /* single-ended samples need to first power up reference voltage; 195 * we leave both ADC and VREF powered 196 */ 197 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \ 198 | ADS_12_BIT | ADS_SER) 199 200 #define REF_ON (READ_12BIT_DFR(x, 1, 1)) 201 #define REF_OFF (READ_12BIT_DFR(y, 0, 0)) 202 203 /* Order commands in the most optimal way to reduce Vref switching and 204 * settling time: 205 * Measure: X; Vref: X+, X-; IN: Y+ 206 * Measure: Y; Vref: Y+, Y-; IN: X+ 207 * Measure: Z1; Vref: Y+, X-; IN: X+ 208 * Measure: Z2; Vref: Y+, X-; IN: Y- 209 */ 210 enum ads7846_cmds { 211 ADS7846_X, 212 ADS7846_Y, 213 ADS7846_Z1, 214 ADS7846_Z2, 215 ADS7846_PWDOWN, 216 }; 217 218 static int get_pendown_state(struct ads7846 *ts) 219 { 220 if (ts->get_pendown_state) 221 return ts->get_pendown_state(); 222 223 return gpiod_get_value(ts->gpio_pendown); 224 } 225 226 static void ads7846_report_pen_up(struct ads7846 *ts) 227 { 228 struct input_dev *input = ts->input; 229 230 input_report_key(input, BTN_TOUCH, 0); 231 input_report_abs(input, ABS_PRESSURE, 0); 232 input_sync(input); 233 234 ts->pendown = false; 235 dev_vdbg(&ts->spi->dev, "UP\n"); 236 } 237 238 /* Must be called with ts->lock held */ 239 static void ads7846_stop(struct ads7846 *ts) 240 { 241 if (!ts->disabled && !ts->suspended) { 242 /* Signal IRQ thread to stop polling and disable the handler. */ 243 ts->stopped = true; 244 mb(); 245 wake_up(&ts->wait); 246 disable_irq(ts->spi->irq); 247 } 248 } 249 250 /* Must be called with ts->lock held */ 251 static void ads7846_restart(struct ads7846 *ts) 252 { 253 if (!ts->disabled && !ts->suspended) { 254 /* Check if pen was released since last stop */ 255 if (ts->pendown && !get_pendown_state(ts)) 256 ads7846_report_pen_up(ts); 257 258 /* Tell IRQ thread that it may poll the device. */ 259 ts->stopped = false; 260 mb(); 261 enable_irq(ts->spi->irq); 262 } 263 } 264 265 /* Must be called with ts->lock held */ 266 static void __ads7846_disable(struct ads7846 *ts) 267 { 268 ads7846_stop(ts); 269 regulator_disable(ts->reg); 270 271 /* 272 * We know the chip's in low power mode since we always 273 * leave it that way after every request 274 */ 275 } 276 277 /* Must be called with ts->lock held */ 278 static void __ads7846_enable(struct ads7846 *ts) 279 { 280 int error; 281 282 error = regulator_enable(ts->reg); 283 if (error != 0) 284 dev_err(&ts->spi->dev, "Failed to enable supply: %d\n", error); 285 286 ads7846_restart(ts); 287 } 288 289 static void ads7846_disable(struct ads7846 *ts) 290 { 291 mutex_lock(&ts->lock); 292 293 if (!ts->disabled) { 294 295 if (!ts->suspended) 296 __ads7846_disable(ts); 297 298 ts->disabled = true; 299 } 300 301 mutex_unlock(&ts->lock); 302 } 303 304 static void ads7846_enable(struct ads7846 *ts) 305 { 306 mutex_lock(&ts->lock); 307 308 if (ts->disabled) { 309 310 ts->disabled = false; 311 312 if (!ts->suspended) 313 __ads7846_enable(ts); 314 } 315 316 mutex_unlock(&ts->lock); 317 } 318 319 /*--------------------------------------------------------------------------*/ 320 321 /* 322 * Non-touchscreen sensors only use single-ended conversions. 323 * The range is GND..vREF. The ads7843 and ads7835 must use external vREF; 324 * ads7846 lets that pin be unconnected, to use internal vREF. 325 */ 326 327 struct ser_req { 328 u8 ref_on; 329 u8 command; 330 u8 ref_off; 331 u16 scratch; 332 struct spi_message msg; 333 struct spi_transfer xfer[6]; 334 /* 335 * DMA (thus cache coherency maintenance) requires the 336 * transfer buffers to live in their own cache lines. 337 */ 338 __be16 sample ____cacheline_aligned; 339 }; 340 341 struct ads7845_ser_req { 342 u8 command[3]; 343 struct spi_message msg; 344 struct spi_transfer xfer[2]; 345 /* 346 * DMA (thus cache coherency maintenance) requires the 347 * transfer buffers to live in their own cache lines. 348 */ 349 u8 sample[3] ____cacheline_aligned; 350 }; 351 352 static int ads7846_read12_ser(struct device *dev, unsigned command) 353 { 354 struct spi_device *spi = to_spi_device(dev); 355 struct ads7846 *ts = dev_get_drvdata(dev); 356 struct ser_req *req; 357 int status; 358 359 req = kzalloc(sizeof *req, GFP_KERNEL); 360 if (!req) 361 return -ENOMEM; 362 363 spi_message_init(&req->msg); 364 365 /* maybe turn on internal vREF, and let it settle */ 366 if (ts->use_internal) { 367 req->ref_on = REF_ON; 368 req->xfer[0].tx_buf = &req->ref_on; 369 req->xfer[0].len = 1; 370 spi_message_add_tail(&req->xfer[0], &req->msg); 371 372 req->xfer[1].rx_buf = &req->scratch; 373 req->xfer[1].len = 2; 374 375 /* for 1uF, settle for 800 usec; no cap, 100 usec. */ 376 req->xfer[1].delay.value = ts->vref_delay_usecs; 377 req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS; 378 spi_message_add_tail(&req->xfer[1], &req->msg); 379 380 /* Enable reference voltage */ 381 command |= ADS_PD10_REF_ON; 382 } 383 384 /* Enable ADC in every case */ 385 command |= ADS_PD10_ADC_ON; 386 387 /* take sample */ 388 req->command = (u8) command; 389 req->xfer[2].tx_buf = &req->command; 390 req->xfer[2].len = 1; 391 spi_message_add_tail(&req->xfer[2], &req->msg); 392 393 req->xfer[3].rx_buf = &req->sample; 394 req->xfer[3].len = 2; 395 spi_message_add_tail(&req->xfer[3], &req->msg); 396 397 /* REVISIT: take a few more samples, and compare ... */ 398 399 /* converter in low power mode & enable PENIRQ */ 400 req->ref_off = PWRDOWN; 401 req->xfer[4].tx_buf = &req->ref_off; 402 req->xfer[4].len = 1; 403 spi_message_add_tail(&req->xfer[4], &req->msg); 404 405 req->xfer[5].rx_buf = &req->scratch; 406 req->xfer[5].len = 2; 407 CS_CHANGE(req->xfer[5]); 408 spi_message_add_tail(&req->xfer[5], &req->msg); 409 410 mutex_lock(&ts->lock); 411 ads7846_stop(ts); 412 status = spi_sync(spi, &req->msg); 413 ads7846_restart(ts); 414 mutex_unlock(&ts->lock); 415 416 if (status == 0) { 417 /* on-wire is a must-ignore bit, a BE12 value, then padding */ 418 status = be16_to_cpu(req->sample); 419 status = status >> 3; 420 status &= 0x0fff; 421 } 422 423 kfree(req); 424 return status; 425 } 426 427 static int ads7845_read12_ser(struct device *dev, unsigned command) 428 { 429 struct spi_device *spi = to_spi_device(dev); 430 struct ads7846 *ts = dev_get_drvdata(dev); 431 struct ads7845_ser_req *req; 432 int status; 433 434 req = kzalloc(sizeof *req, GFP_KERNEL); 435 if (!req) 436 return -ENOMEM; 437 438 spi_message_init(&req->msg); 439 440 req->command[0] = (u8) command; 441 req->xfer[0].tx_buf = req->command; 442 req->xfer[0].rx_buf = req->sample; 443 req->xfer[0].len = 3; 444 spi_message_add_tail(&req->xfer[0], &req->msg); 445 446 mutex_lock(&ts->lock); 447 ads7846_stop(ts); 448 status = spi_sync(spi, &req->msg); 449 ads7846_restart(ts); 450 mutex_unlock(&ts->lock); 451 452 if (status == 0) { 453 /* BE12 value, then padding */ 454 status = get_unaligned_be16(&req->sample[1]); 455 status = status >> 3; 456 status &= 0x0fff; 457 } 458 459 kfree(req); 460 return status; 461 } 462 463 #if IS_ENABLED(CONFIG_HWMON) 464 465 #define SHOW(name, var, adjust) static ssize_t \ 466 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \ 467 { \ 468 struct ads7846 *ts = dev_get_drvdata(dev); \ 469 ssize_t v = ads7846_read12_ser(&ts->spi->dev, \ 470 READ_12BIT_SER(var)); \ 471 if (v < 0) \ 472 return v; \ 473 return sprintf(buf, "%u\n", adjust(ts, v)); \ 474 } \ 475 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL); 476 477 478 /* Sysfs conventions report temperatures in millidegrees Celsius. 479 * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high 480 * accuracy scheme without calibration data. For now we won't try either; 481 * userspace sees raw sensor values, and must scale/calibrate appropriately. 482 */ 483 static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v) 484 { 485 return v; 486 } 487 488 SHOW(temp0, temp0, null_adjust) /* temp1_input */ 489 SHOW(temp1, temp1, null_adjust) /* temp2_input */ 490 491 492 /* sysfs conventions report voltages in millivolts. We can convert voltages 493 * if we know vREF. userspace may need to scale vAUX to match the board's 494 * external resistors; we assume that vBATT only uses the internal ones. 495 */ 496 static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v) 497 { 498 unsigned retval = v; 499 500 /* external resistors may scale vAUX into 0..vREF */ 501 retval *= ts->vref_mv; 502 retval = retval >> 12; 503 504 return retval; 505 } 506 507 static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v) 508 { 509 unsigned retval = vaux_adjust(ts, v); 510 511 /* ads7846 has a resistor ladder to scale this signal down */ 512 if (ts->model == 7846) 513 retval *= 4; 514 515 return retval; 516 } 517 518 SHOW(in0_input, vaux, vaux_adjust) 519 SHOW(in1_input, vbatt, vbatt_adjust) 520 521 static umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr, 522 int index) 523 { 524 struct device *dev = kobj_to_dev(kobj); 525 struct ads7846 *ts = dev_get_drvdata(dev); 526 527 if (ts->model == 7843 && index < 2) /* in0, in1 */ 528 return 0; 529 if (ts->model == 7845 && index != 2) /* in0 */ 530 return 0; 531 532 return attr->mode; 533 } 534 535 static struct attribute *ads7846_attributes[] = { 536 &dev_attr_temp0.attr, /* 0 */ 537 &dev_attr_temp1.attr, /* 1 */ 538 &dev_attr_in0_input.attr, /* 2 */ 539 &dev_attr_in1_input.attr, /* 3 */ 540 NULL, 541 }; 542 543 static const struct attribute_group ads7846_attr_group = { 544 .attrs = ads7846_attributes, 545 .is_visible = ads7846_is_visible, 546 }; 547 __ATTRIBUTE_GROUPS(ads7846_attr); 548 549 static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts) 550 { 551 struct device *hwmon; 552 553 /* hwmon sensors need a reference voltage */ 554 switch (ts->model) { 555 case 7846: 556 if (!ts->vref_mv) { 557 dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n"); 558 ts->vref_mv = 2500; 559 ts->use_internal = true; 560 } 561 break; 562 case 7845: 563 case 7843: 564 if (!ts->vref_mv) { 565 dev_warn(&spi->dev, 566 "external vREF for ADS%d not specified\n", 567 ts->model); 568 return 0; 569 } 570 break; 571 } 572 573 hwmon = devm_hwmon_device_register_with_groups(&spi->dev, 574 spi->modalias, ts, 575 ads7846_attr_groups); 576 577 return PTR_ERR_OR_ZERO(hwmon); 578 } 579 580 #else 581 static inline int ads784x_hwmon_register(struct spi_device *spi, 582 struct ads7846 *ts) 583 { 584 return 0; 585 } 586 #endif 587 588 static ssize_t ads7846_pen_down_show(struct device *dev, 589 struct device_attribute *attr, char *buf) 590 { 591 struct ads7846 *ts = dev_get_drvdata(dev); 592 593 return sprintf(buf, "%u\n", ts->pendown); 594 } 595 596 static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL); 597 598 static ssize_t ads7846_disable_show(struct device *dev, 599 struct device_attribute *attr, char *buf) 600 { 601 struct ads7846 *ts = dev_get_drvdata(dev); 602 603 return sprintf(buf, "%u\n", ts->disabled); 604 } 605 606 static ssize_t ads7846_disable_store(struct device *dev, 607 struct device_attribute *attr, 608 const char *buf, size_t count) 609 { 610 struct ads7846 *ts = dev_get_drvdata(dev); 611 unsigned int i; 612 int err; 613 614 err = kstrtouint(buf, 10, &i); 615 if (err) 616 return err; 617 618 if (i) 619 ads7846_disable(ts); 620 else 621 ads7846_enable(ts); 622 623 return count; 624 } 625 626 static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store); 627 628 static struct attribute *ads784x_attrs[] = { 629 &dev_attr_pen_down.attr, 630 &dev_attr_disable.attr, 631 NULL, 632 }; 633 ATTRIBUTE_GROUPS(ads784x); 634 635 /*--------------------------------------------------------------------------*/ 636 637 static void null_wait_for_sync(void) 638 { 639 } 640 641 static int ads7846_debounce_filter(void *ads, int data_idx, int *val) 642 { 643 struct ads7846 *ts = ads; 644 645 if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) { 646 /* Start over collecting consistent readings. */ 647 ts->read_rep = 0; 648 /* 649 * Repeat it, if this was the first read or the read 650 * wasn't consistent enough. 651 */ 652 if (ts->read_cnt < ts->debounce_max) { 653 ts->last_read = *val; 654 ts->read_cnt++; 655 return ADS7846_FILTER_REPEAT; 656 } else { 657 /* 658 * Maximum number of debouncing reached and still 659 * not enough number of consistent readings. Abort 660 * the whole sample, repeat it in the next sampling 661 * period. 662 */ 663 ts->read_cnt = 0; 664 return ADS7846_FILTER_IGNORE; 665 } 666 } else { 667 if (++ts->read_rep > ts->debounce_rep) { 668 /* 669 * Got a good reading for this coordinate, 670 * go for the next one. 671 */ 672 ts->read_cnt = 0; 673 ts->read_rep = 0; 674 return ADS7846_FILTER_OK; 675 } else { 676 /* Read more values that are consistent. */ 677 ts->read_cnt++; 678 return ADS7846_FILTER_REPEAT; 679 } 680 } 681 } 682 683 static int ads7846_no_filter(void *ads, int data_idx, int *val) 684 { 685 return ADS7846_FILTER_OK; 686 } 687 688 static int ads7846_get_value(struct ads7846_buf *buf) 689 { 690 int value; 691 692 value = be16_to_cpup(&buf->data); 693 694 /* enforce ADC output is 12 bits width */ 695 return (value >> 3) & 0xfff; 696 } 697 698 static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx, 699 u16 val) 700 { 701 struct ads7846_packet *packet = ts->packet; 702 703 switch (cmd_idx) { 704 case ADS7846_Y: 705 packet->y = val; 706 break; 707 case ADS7846_X: 708 packet->x = val; 709 break; 710 case ADS7846_Z1: 711 packet->z1 = val; 712 break; 713 case ADS7846_Z2: 714 packet->z2 = val; 715 break; 716 default: 717 WARN_ON_ONCE(1); 718 } 719 } 720 721 static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref) 722 { 723 switch (cmd_idx) { 724 case ADS7846_Y: 725 return READ_Y(vref); 726 case ADS7846_X: 727 return READ_X(vref); 728 729 /* 7846 specific commands */ 730 case ADS7846_Z1: 731 return READ_Z1(vref); 732 case ADS7846_Z2: 733 return READ_Z2(vref); 734 case ADS7846_PWDOWN: 735 return PWRDOWN; 736 default: 737 WARN_ON_ONCE(1); 738 } 739 740 return 0; 741 } 742 743 static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx) 744 { 745 switch (cmd_idx) { 746 case ADS7846_X: 747 case ADS7846_Y: 748 case ADS7846_Z1: 749 case ADS7846_Z2: 750 return true; 751 case ADS7846_PWDOWN: 752 return false; 753 default: 754 WARN_ON_ONCE(1); 755 } 756 757 return false; 758 } 759 760 static int ads7846_filter(struct ads7846 *ts) 761 { 762 struct ads7846_packet *packet = ts->packet; 763 int action; 764 int val; 765 unsigned int cmd_idx, b; 766 767 packet->ignore = false; 768 for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) { 769 struct ads7846_buf_layout *l = &packet->l[cmd_idx]; 770 771 packet->last_cmd_idx = cmd_idx; 772 773 for (b = l->skip; b < l->count; b++) { 774 val = ads7846_get_value(&packet->rx[l->offset + b]); 775 776 action = ts->filter(ts->filter_data, cmd_idx, &val); 777 if (action == ADS7846_FILTER_REPEAT) { 778 if (b == l->count - 1) 779 return -EAGAIN; 780 } else if (action == ADS7846_FILTER_OK) { 781 ads7846_set_cmd_val(ts, cmd_idx, val); 782 break; 783 } else { 784 packet->ignore = true; 785 return 0; 786 } 787 } 788 } 789 790 return 0; 791 } 792 793 static void ads7846_read_state(struct ads7846 *ts) 794 { 795 struct ads7846_packet *packet = ts->packet; 796 struct spi_message *m; 797 int msg_idx = 0; 798 int error; 799 800 packet->last_cmd_idx = 0; 801 802 while (true) { 803 ts->wait_for_sync(); 804 805 m = &ts->msg[msg_idx]; 806 error = spi_sync(ts->spi, m); 807 if (error) { 808 dev_err(&ts->spi->dev, "spi_sync --> %d\n", error); 809 packet->ignore = true; 810 return; 811 } 812 813 error = ads7846_filter(ts); 814 if (error) 815 continue; 816 817 return; 818 } 819 } 820 821 static void ads7846_report_state(struct ads7846 *ts) 822 { 823 struct ads7846_packet *packet = ts->packet; 824 unsigned int Rt; 825 u16 x, y, z1, z2; 826 827 x = packet->x; 828 y = packet->y; 829 if (ts->model == 7845) { 830 z1 = 0; 831 z2 = 0; 832 } else { 833 z1 = packet->z1; 834 z2 = packet->z2; 835 } 836 837 /* range filtering */ 838 if (x == MAX_12BIT) 839 x = 0; 840 841 if (ts->model == 7843 || ts->model == 7845) { 842 Rt = ts->pressure_max / 2; 843 } else if (likely(x && z1)) { 844 /* compute touch pressure resistance using equation #2 */ 845 Rt = z2; 846 Rt -= z1; 847 Rt *= ts->x_plate_ohms; 848 Rt = DIV_ROUND_CLOSEST(Rt, 16); 849 Rt *= x; 850 Rt /= z1; 851 Rt = DIV_ROUND_CLOSEST(Rt, 256); 852 } else { 853 Rt = 0; 854 } 855 856 /* 857 * Sample found inconsistent by debouncing or pressure is beyond 858 * the maximum. Don't report it to user space, repeat at least 859 * once more the measurement 860 */ 861 if (packet->ignore || Rt > ts->pressure_max) { 862 dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n", 863 packet->ignore, Rt); 864 return; 865 } 866 867 /* 868 * Maybe check the pendown state before reporting. This discards 869 * false readings when the pen is lifted. 870 */ 871 if (ts->penirq_recheck_delay_usecs) { 872 udelay(ts->penirq_recheck_delay_usecs); 873 if (!get_pendown_state(ts)) 874 Rt = 0; 875 } 876 877 /* 878 * NOTE: We can't rely on the pressure to determine the pen down 879 * state, even this controller has a pressure sensor. The pressure 880 * value can fluctuate for quite a while after lifting the pen and 881 * in some cases may not even settle at the expected value. 882 * 883 * The only safe way to check for the pen up condition is in the 884 * timer by reading the pen signal state (it's a GPIO _and_ IRQ). 885 */ 886 if (Rt) { 887 struct input_dev *input = ts->input; 888 889 if (!ts->pendown) { 890 input_report_key(input, BTN_TOUCH, 1); 891 ts->pendown = true; 892 dev_vdbg(&ts->spi->dev, "DOWN\n"); 893 } 894 895 touchscreen_report_pos(input, &ts->core_prop, x, y, false); 896 input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt); 897 898 input_sync(input); 899 dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt); 900 } 901 } 902 903 static irqreturn_t ads7846_hard_irq(int irq, void *handle) 904 { 905 struct ads7846 *ts = handle; 906 907 return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED; 908 } 909 910 911 static irqreturn_t ads7846_irq(int irq, void *handle) 912 { 913 struct ads7846 *ts = handle; 914 915 /* Start with a small delay before checking pendown state */ 916 msleep(TS_POLL_DELAY); 917 918 while (!ts->stopped && get_pendown_state(ts)) { 919 920 /* pen is down, continue with the measurement */ 921 ads7846_read_state(ts); 922 923 if (!ts->stopped) 924 ads7846_report_state(ts); 925 926 wait_event_timeout(ts->wait, ts->stopped, 927 msecs_to_jiffies(TS_POLL_PERIOD)); 928 } 929 930 if (ts->pendown && !ts->stopped) 931 ads7846_report_pen_up(ts); 932 933 return IRQ_HANDLED; 934 } 935 936 static int ads7846_suspend(struct device *dev) 937 { 938 struct ads7846 *ts = dev_get_drvdata(dev); 939 940 mutex_lock(&ts->lock); 941 942 if (!ts->suspended) { 943 944 if (!ts->disabled) 945 __ads7846_disable(ts); 946 947 if (device_may_wakeup(&ts->spi->dev)) 948 enable_irq_wake(ts->spi->irq); 949 950 ts->suspended = true; 951 } 952 953 mutex_unlock(&ts->lock); 954 955 return 0; 956 } 957 958 static int ads7846_resume(struct device *dev) 959 { 960 struct ads7846 *ts = dev_get_drvdata(dev); 961 962 mutex_lock(&ts->lock); 963 964 if (ts->suspended) { 965 966 ts->suspended = false; 967 968 if (device_may_wakeup(&ts->spi->dev)) 969 disable_irq_wake(ts->spi->irq); 970 971 if (!ts->disabled) 972 __ads7846_enable(ts); 973 } 974 975 mutex_unlock(&ts->lock); 976 977 return 0; 978 } 979 980 static DEFINE_SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume); 981 982 static int ads7846_setup_pendown(struct spi_device *spi, 983 struct ads7846 *ts, 984 const struct ads7846_platform_data *pdata) 985 { 986 /* 987 * REVISIT when the irq can be triggered active-low, or if for some 988 * reason the touchscreen isn't hooked up, we don't need to access 989 * the pendown state. 990 */ 991 992 if (pdata->get_pendown_state) { 993 ts->get_pendown_state = pdata->get_pendown_state; 994 } else { 995 ts->gpio_pendown = gpiod_get(&spi->dev, "pendown", GPIOD_IN); 996 if (IS_ERR(ts->gpio_pendown)) { 997 dev_err(&spi->dev, "failed to request pendown GPIO\n"); 998 return PTR_ERR(ts->gpio_pendown); 999 } 1000 if (pdata->gpio_pendown_debounce) 1001 gpiod_set_debounce(ts->gpio_pendown, 1002 pdata->gpio_pendown_debounce); 1003 } 1004 1005 return 0; 1006 } 1007 1008 /* 1009 * Set up the transfers to read touchscreen state; this assumes we 1010 * use formula #2 for pressure, not #3. 1011 */ 1012 static int ads7846_setup_spi_msg(struct ads7846 *ts, 1013 const struct ads7846_platform_data *pdata) 1014 { 1015 struct spi_message *m = &ts->msg[0]; 1016 struct spi_transfer *x = ts->xfer; 1017 struct ads7846_packet *packet = ts->packet; 1018 int vref = pdata->keep_vref_on; 1019 unsigned int count, offset = 0; 1020 unsigned int cmd_idx, b; 1021 unsigned long time; 1022 size_t size = 0; 1023 1024 /* time per bit */ 1025 time = NSEC_PER_SEC / ts->spi->max_speed_hz; 1026 1027 count = pdata->settle_delay_usecs * NSEC_PER_USEC / time; 1028 packet->count_skip = DIV_ROUND_UP(count, 24); 1029 1030 if (ts->debounce_max && ts->debounce_rep) 1031 /* ads7846_debounce_filter() is making ts->debounce_rep + 2 1032 * reads. So we need to get all samples for normal case. */ 1033 packet->count = ts->debounce_rep + 2; 1034 else 1035 packet->count = 1; 1036 1037 if (ts->model == 7846) 1038 packet->cmds = 5; /* x, y, z1, z2, pwdown */ 1039 else 1040 packet->cmds = 3; /* x, y, pwdown */ 1041 1042 for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) { 1043 struct ads7846_buf_layout *l = &packet->l[cmd_idx]; 1044 unsigned int max_count; 1045 1046 if (cmd_idx == packet->cmds - 1) 1047 cmd_idx = ADS7846_PWDOWN; 1048 1049 if (ads7846_cmd_need_settle(cmd_idx)) 1050 max_count = packet->count + packet->count_skip; 1051 else 1052 max_count = packet->count; 1053 1054 l->offset = offset; 1055 offset += max_count; 1056 l->count = max_count; 1057 l->skip = packet->count_skip; 1058 size += sizeof(*packet->tx) * max_count; 1059 } 1060 1061 packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL); 1062 if (!packet->tx) 1063 return -ENOMEM; 1064 1065 packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL); 1066 if (!packet->rx) 1067 return -ENOMEM; 1068 1069 if (ts->model == 7873) { 1070 /* 1071 * The AD7873 is almost identical to the ADS7846 1072 * keep VREF off during differential/ratiometric 1073 * conversion modes. 1074 */ 1075 ts->model = 7846; 1076 vref = 0; 1077 } 1078 1079 ts->msg_count = 1; 1080 spi_message_init(m); 1081 m->context = ts; 1082 1083 for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) { 1084 struct ads7846_buf_layout *l = &packet->l[cmd_idx]; 1085 u8 cmd; 1086 1087 if (cmd_idx == packet->cmds - 1) 1088 cmd_idx = ADS7846_PWDOWN; 1089 1090 cmd = ads7846_get_cmd(cmd_idx, vref); 1091 1092 for (b = 0; b < l->count; b++) 1093 packet->tx[l->offset + b].cmd = cmd; 1094 } 1095 1096 x->tx_buf = packet->tx; 1097 x->rx_buf = packet->rx; 1098 x->len = size; 1099 spi_message_add_tail(x, m); 1100 1101 return 0; 1102 } 1103 1104 static const struct of_device_id ads7846_dt_ids[] = { 1105 { .compatible = "ti,tsc2046", .data = (void *) 7846 }, 1106 { .compatible = "ti,ads7843", .data = (void *) 7843 }, 1107 { .compatible = "ti,ads7845", .data = (void *) 7845 }, 1108 { .compatible = "ti,ads7846", .data = (void *) 7846 }, 1109 { .compatible = "ti,ads7873", .data = (void *) 7873 }, 1110 { } 1111 }; 1112 MODULE_DEVICE_TABLE(of, ads7846_dt_ids); 1113 1114 static const struct ads7846_platform_data *ads7846_get_props(struct device *dev) 1115 { 1116 struct ads7846_platform_data *pdata; 1117 u32 value; 1118 1119 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); 1120 if (!pdata) 1121 return ERR_PTR(-ENOMEM); 1122 1123 pdata->model = (uintptr_t)device_get_match_data(dev); 1124 1125 device_property_read_u16(dev, "ti,vref-delay-usecs", 1126 &pdata->vref_delay_usecs); 1127 device_property_read_u16(dev, "ti,vref-mv", &pdata->vref_mv); 1128 pdata->keep_vref_on = device_property_read_bool(dev, "ti,keep-vref-on"); 1129 1130 pdata->swap_xy = device_property_read_bool(dev, "ti,swap-xy"); 1131 1132 device_property_read_u16(dev, "ti,settle-delay-usec", 1133 &pdata->settle_delay_usecs); 1134 device_property_read_u16(dev, "ti,penirq-recheck-delay-usecs", 1135 &pdata->penirq_recheck_delay_usecs); 1136 1137 device_property_read_u16(dev, "ti,x-plate-ohms", &pdata->x_plate_ohms); 1138 device_property_read_u16(dev, "ti,y-plate-ohms", &pdata->y_plate_ohms); 1139 1140 device_property_read_u16(dev, "ti,x-min", &pdata->x_min); 1141 device_property_read_u16(dev, "ti,y-min", &pdata->y_min); 1142 device_property_read_u16(dev, "ti,x-max", &pdata->x_max); 1143 device_property_read_u16(dev, "ti,y-max", &pdata->y_max); 1144 1145 /* 1146 * touchscreen-max-pressure gets parsed during 1147 * touchscreen_parse_properties() 1148 */ 1149 device_property_read_u16(dev, "ti,pressure-min", &pdata->pressure_min); 1150 if (!device_property_read_u32(dev, "touchscreen-min-pressure", &value)) 1151 pdata->pressure_min = (u16) value; 1152 device_property_read_u16(dev, "ti,pressure-max", &pdata->pressure_max); 1153 1154 device_property_read_u16(dev, "ti,debounce-max", &pdata->debounce_max); 1155 if (!device_property_read_u32(dev, "touchscreen-average-samples", &value)) 1156 pdata->debounce_max = (u16) value; 1157 device_property_read_u16(dev, "ti,debounce-tol", &pdata->debounce_tol); 1158 device_property_read_u16(dev, "ti,debounce-rep", &pdata->debounce_rep); 1159 1160 device_property_read_u32(dev, "ti,pendown-gpio-debounce", 1161 &pdata->gpio_pendown_debounce); 1162 1163 pdata->wakeup = device_property_read_bool(dev, "wakeup-source") || 1164 device_property_read_bool(dev, "linux,wakeup"); 1165 1166 return pdata; 1167 } 1168 1169 static void ads7846_regulator_disable(void *regulator) 1170 { 1171 regulator_disable(regulator); 1172 } 1173 1174 static int ads7846_probe(struct spi_device *spi) 1175 { 1176 const struct ads7846_platform_data *pdata; 1177 struct ads7846 *ts; 1178 struct device *dev = &spi->dev; 1179 struct ads7846_packet *packet; 1180 struct input_dev *input_dev; 1181 unsigned long irq_flags; 1182 int err; 1183 1184 if (!spi->irq) { 1185 dev_dbg(dev, "no IRQ?\n"); 1186 return -EINVAL; 1187 } 1188 1189 /* don't exceed max specified sample rate */ 1190 if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { 1191 dev_err(dev, "f(sample) %d KHz?\n", 1192 (spi->max_speed_hz/SAMPLE_BITS)/1000); 1193 return -EINVAL; 1194 } 1195 1196 /* 1197 * We'd set TX word size 8 bits and RX word size to 13 bits ... except 1198 * that even if the hardware can do that, the SPI controller driver 1199 * may not. So we stick to very-portable 8 bit words, both RX and TX. 1200 */ 1201 spi->bits_per_word = 8; 1202 spi->mode &= ~SPI_MODE_X_MASK; 1203 spi->mode |= SPI_MODE_0; 1204 err = spi_setup(spi); 1205 if (err < 0) 1206 return err; 1207 1208 ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL); 1209 if (!ts) 1210 return -ENOMEM; 1211 1212 packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL); 1213 if (!packet) 1214 return -ENOMEM; 1215 1216 input_dev = devm_input_allocate_device(dev); 1217 if (!input_dev) 1218 return -ENOMEM; 1219 1220 spi_set_drvdata(spi, ts); 1221 1222 ts->packet = packet; 1223 ts->spi = spi; 1224 ts->input = input_dev; 1225 1226 mutex_init(&ts->lock); 1227 init_waitqueue_head(&ts->wait); 1228 1229 pdata = dev_get_platdata(dev); 1230 if (!pdata) { 1231 pdata = ads7846_get_props(dev); 1232 if (IS_ERR(pdata)) 1233 return PTR_ERR(pdata); 1234 } 1235 1236 ts->model = pdata->model ? : 7846; 1237 ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; 1238 ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; 1239 ts->vref_mv = pdata->vref_mv; 1240 1241 if (pdata->debounce_max) { 1242 ts->debounce_max = pdata->debounce_max; 1243 if (ts->debounce_max < 2) 1244 ts->debounce_max = 2; 1245 ts->debounce_tol = pdata->debounce_tol; 1246 ts->debounce_rep = pdata->debounce_rep; 1247 ts->filter = ads7846_debounce_filter; 1248 ts->filter_data = ts; 1249 } else { 1250 ts->filter = ads7846_no_filter; 1251 } 1252 1253 err = ads7846_setup_pendown(spi, ts, pdata); 1254 if (err) 1255 return err; 1256 1257 if (pdata->penirq_recheck_delay_usecs) 1258 ts->penirq_recheck_delay_usecs = 1259 pdata->penirq_recheck_delay_usecs; 1260 1261 ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync; 1262 1263 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev)); 1264 snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model); 1265 1266 input_dev->name = ts->name; 1267 input_dev->phys = ts->phys; 1268 1269 input_dev->id.bustype = BUS_SPI; 1270 input_dev->id.product = pdata->model; 1271 1272 input_set_capability(input_dev, EV_KEY, BTN_TOUCH); 1273 input_set_abs_params(input_dev, ABS_X, 1274 pdata->x_min ? : 0, 1275 pdata->x_max ? : MAX_12BIT, 1276 0, 0); 1277 input_set_abs_params(input_dev, ABS_Y, 1278 pdata->y_min ? : 0, 1279 pdata->y_max ? : MAX_12BIT, 1280 0, 0); 1281 if (ts->model != 7845) 1282 input_set_abs_params(input_dev, ABS_PRESSURE, 1283 pdata->pressure_min, pdata->pressure_max, 0, 0); 1284 1285 /* 1286 * Parse common framework properties. Must be done here to ensure the 1287 * correct behaviour in case of using the legacy vendor bindings. The 1288 * general binding value overrides the vendor specific one. 1289 */ 1290 touchscreen_parse_properties(ts->input, false, &ts->core_prop); 1291 ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0; 1292 1293 /* 1294 * Check if legacy ti,swap-xy binding is used instead of 1295 * touchscreen-swapped-x-y 1296 */ 1297 if (!ts->core_prop.swap_x_y && pdata->swap_xy) { 1298 swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]); 1299 ts->core_prop.swap_x_y = true; 1300 } 1301 1302 ads7846_setup_spi_msg(ts, pdata); 1303 1304 ts->reg = devm_regulator_get(dev, "vcc"); 1305 if (IS_ERR(ts->reg)) { 1306 err = PTR_ERR(ts->reg); 1307 dev_err(dev, "unable to get regulator: %d\n", err); 1308 return err; 1309 } 1310 1311 err = regulator_enable(ts->reg); 1312 if (err) { 1313 dev_err(dev, "unable to enable regulator: %d\n", err); 1314 return err; 1315 } 1316 1317 err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg); 1318 if (err) 1319 return err; 1320 1321 irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING; 1322 irq_flags |= IRQF_ONESHOT; 1323 1324 err = devm_request_threaded_irq(dev, spi->irq, 1325 ads7846_hard_irq, ads7846_irq, 1326 irq_flags, dev->driver->name, ts); 1327 if (err && err != -EPROBE_DEFER && !pdata->irq_flags) { 1328 dev_info(dev, 1329 "trying pin change workaround on irq %d\n", spi->irq); 1330 irq_flags |= IRQF_TRIGGER_RISING; 1331 err = devm_request_threaded_irq(dev, spi->irq, 1332 ads7846_hard_irq, ads7846_irq, 1333 irq_flags, dev->driver->name, 1334 ts); 1335 } 1336 1337 if (err) { 1338 dev_dbg(dev, "irq %d busy?\n", spi->irq); 1339 return err; 1340 } 1341 1342 err = ads784x_hwmon_register(spi, ts); 1343 if (err) 1344 return err; 1345 1346 dev_info(dev, "touchscreen, irq %d\n", spi->irq); 1347 1348 /* 1349 * Take a first sample, leaving nPENIRQ active and vREF off; avoid 1350 * the touchscreen, in case it's not connected. 1351 */ 1352 if (ts->model == 7845) 1353 ads7845_read12_ser(dev, PWRDOWN); 1354 else 1355 (void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux)); 1356 1357 err = input_register_device(input_dev); 1358 if (err) 1359 return err; 1360 1361 device_init_wakeup(dev, pdata->wakeup); 1362 1363 /* 1364 * If device does not carry platform data we must have allocated it 1365 * when parsing DT data. 1366 */ 1367 if (!dev_get_platdata(dev)) 1368 devm_kfree(dev, (void *)pdata); 1369 1370 return 0; 1371 } 1372 1373 static void ads7846_remove(struct spi_device *spi) 1374 { 1375 struct ads7846 *ts = spi_get_drvdata(spi); 1376 1377 ads7846_stop(ts); 1378 } 1379 1380 static struct spi_driver ads7846_driver = { 1381 .driver = { 1382 .name = "ads7846", 1383 .dev_groups = ads784x_groups, 1384 .pm = pm_sleep_ptr(&ads7846_pm), 1385 .of_match_table = ads7846_dt_ids, 1386 }, 1387 .probe = ads7846_probe, 1388 .remove = ads7846_remove, 1389 }; 1390 1391 module_spi_driver(ads7846_driver); 1392 1393 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver"); 1394 MODULE_LICENSE("GPL"); 1395 MODULE_ALIAS("spi:ads7846"); 1396