1 /* 2 * ADS7846 based touchscreen and sensor driver 3 * 4 * Copyright (c) 2005 David Brownell 5 * 6 * Using code from: 7 * - corgi_ts.c 8 * Copyright (C) 2004-2005 Richard Purdie 9 * - omap_ts.[hc], ads7846.h, ts_osk.c 10 * Copyright (C) 2002 MontaVista Software 11 * Copyright (C) 2004 Texas Instruments 12 * Copyright (C) 2005 Dirk Behme 13 * 14 * This program is free software; you can redistribute it and/or modify 15 * it under the terms of the GNU General Public License version 2 as 16 * published by the Free Software Foundation. 17 */ 18 #include <linux/device.h> 19 #include <linux/init.h> 20 #include <linux/delay.h> 21 #include <linux/input.h> 22 #include <linux/interrupt.h> 23 #include <linux/slab.h> 24 #include <linux/spi/spi.h> 25 #include <linux/spi/ads7846.h> 26 #include <linux/interrupt.h> 27 28 #ifdef CONFIG_ARM 29 #include <asm/mach-types.h> 30 #ifdef CONFIG_ARCH_OMAP 31 #include <asm/arch/gpio.h> 32 #endif 33 #endif 34 35 36 /* 37 * This code has been lightly tested on an ads7846. 38 * Support for ads7843 and ads7845 has only been stubbed in. 39 * 40 * Not yet done: investigate the values reported. Are x/y/pressure 41 * event values sane enough for X11? How accurate are the temperature 42 * and voltage readings? (System-specific calibration should support 43 * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.) 44 * 45 * app note sbaa036 talks in more detail about accurate sampling... 46 * that ought to help in situations like LCDs inducing noise (which 47 * can also be helped by using synch signals) and more generally. 48 */ 49 50 #define TS_POLL_PERIOD msecs_to_jiffies(10) 51 52 /* this driver doesn't aim at the peak continuous sample rate */ 53 #define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */) 54 55 struct ts_event { 56 /* For portability, we can't read 12 bit values using SPI (which 57 * would make the controller deliver them as native byteorder u16 58 * with msbs zeroed). Instead, we read them as two 8-bit values, 59 * which need byteswapping then range adjustment. 60 */ 61 __be16 x; 62 __be16 y; 63 __be16 z1, z2; 64 }; 65 66 struct ads7846 { 67 struct input_dev *input; 68 char phys[32]; 69 70 struct spi_device *spi; 71 u16 model; 72 u16 vref_delay_usecs; 73 u16 x_plate_ohms; 74 75 u8 read_x, read_y, read_z1, read_z2; 76 struct ts_event tc; 77 78 struct spi_transfer xfer[8]; 79 struct spi_message msg; 80 81 spinlock_t lock; 82 struct timer_list timer; /* P: lock */ 83 unsigned pendown:1; /* P: lock */ 84 unsigned pending:1; /* P: lock */ 85 // FIXME remove "irq_disabled" 86 unsigned irq_disabled:1; /* P: lock */ 87 }; 88 89 /* leave chip selected when we're done, for quicker re-select? */ 90 #if 0 91 #define CS_CHANGE(xfer) ((xfer).cs_change = 1) 92 #else 93 #define CS_CHANGE(xfer) ((xfer).cs_change = 0) 94 #endif 95 96 /*--------------------------------------------------------------------------*/ 97 98 /* The ADS7846 has touchscreen and other sensors. 99 * Earlier ads784x chips are somewhat compatible. 100 */ 101 #define ADS_START (1 << 7) 102 #define ADS_A2A1A0_d_y (1 << 4) /* differential */ 103 #define ADS_A2A1A0_d_z1 (3 << 4) /* differential */ 104 #define ADS_A2A1A0_d_z2 (4 << 4) /* differential */ 105 #define ADS_A2A1A0_d_x (5 << 4) /* differential */ 106 #define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */ 107 #define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */ 108 #define ADS_A2A1A0_vaux (6 << 4) /* non-differential */ 109 #define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */ 110 #define ADS_8_BIT (1 << 3) 111 #define ADS_12_BIT (0 << 3) 112 #define ADS_SER (1 << 2) /* non-differential */ 113 #define ADS_DFR (0 << 2) /* differential */ 114 #define ADS_PD10_PDOWN (0 << 0) /* lowpower mode + penirq */ 115 #define ADS_PD10_ADC_ON (1 << 0) /* ADC on */ 116 #define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */ 117 #define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */ 118 119 #define MAX_12BIT ((1<<12)-1) 120 121 /* leave ADC powered up (disables penirq) between differential samples */ 122 #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \ 123 | ADS_12_BIT | ADS_DFR) 124 125 #define READ_Y (READ_12BIT_DFR(y) | ADS_PD10_ADC_ON) 126 #define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON) 127 #define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON) 128 #define READ_X (READ_12BIT_DFR(x) | ADS_PD10_PDOWN) /* LAST */ 129 130 /* single-ended samples need to first power up reference voltage; 131 * we leave both ADC and VREF powered 132 */ 133 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \ 134 | ADS_12_BIT | ADS_SER) 135 136 #define REF_ON (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON) 137 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN) 138 139 /*--------------------------------------------------------------------------*/ 140 141 /* 142 * Non-touchscreen sensors only use single-ended conversions. 143 */ 144 145 struct ser_req { 146 u8 ref_on; 147 u8 command; 148 u8 ref_off; 149 u16 scratch; 150 __be16 sample; 151 struct spi_message msg; 152 struct spi_transfer xfer[6]; 153 }; 154 155 static int ads7846_read12_ser(struct device *dev, unsigned command) 156 { 157 struct spi_device *spi = to_spi_device(dev); 158 struct ads7846 *ts = dev_get_drvdata(dev); 159 struct ser_req *req = kzalloc(sizeof *req, SLAB_KERNEL); 160 int status; 161 int sample; 162 int i; 163 164 if (!req) 165 return -ENOMEM; 166 167 INIT_LIST_HEAD(&req->msg.transfers); 168 169 /* activate reference, so it has time to settle; */ 170 req->ref_on = REF_ON; 171 req->xfer[0].tx_buf = &req->ref_on; 172 req->xfer[0].len = 1; 173 req->xfer[1].rx_buf = &req->scratch; 174 req->xfer[1].len = 2; 175 176 /* 177 * for external VREF, 0 usec (and assume it's always on); 178 * for 1uF, use 800 usec; 179 * no cap, 100 usec. 180 */ 181 req->xfer[1].delay_usecs = ts->vref_delay_usecs; 182 183 /* take sample */ 184 req->command = (u8) command; 185 req->xfer[2].tx_buf = &req->command; 186 req->xfer[2].len = 1; 187 req->xfer[3].rx_buf = &req->sample; 188 req->xfer[3].len = 2; 189 190 /* REVISIT: take a few more samples, and compare ... */ 191 192 /* turn off reference */ 193 req->ref_off = REF_OFF; 194 req->xfer[4].tx_buf = &req->ref_off; 195 req->xfer[4].len = 1; 196 req->xfer[5].rx_buf = &req->scratch; 197 req->xfer[5].len = 2; 198 199 CS_CHANGE(req->xfer[5]); 200 201 /* group all the transfers together, so we can't interfere with 202 * reading touchscreen state; disable penirq while sampling 203 */ 204 for (i = 0; i < 6; i++) 205 spi_message_add_tail(&req->xfer[i], &req->msg); 206 207 disable_irq(spi->irq); 208 status = spi_sync(spi, &req->msg); 209 enable_irq(spi->irq); 210 211 if (req->msg.status) 212 status = req->msg.status; 213 sample = be16_to_cpu(req->sample); 214 sample = sample >> 4; 215 kfree(req); 216 217 return status ? status : sample; 218 } 219 220 #define SHOW(name) static ssize_t \ 221 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \ 222 { \ 223 ssize_t v = ads7846_read12_ser(dev, \ 224 READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \ 225 if (v < 0) \ 226 return v; \ 227 return sprintf(buf, "%u\n", (unsigned) v); \ 228 } \ 229 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL); 230 231 SHOW(temp0) 232 SHOW(temp1) 233 SHOW(vaux) 234 SHOW(vbatt) 235 236 /*--------------------------------------------------------------------------*/ 237 238 /* 239 * PENIRQ only kicks the timer. The timer only reissues the SPI transfer, 240 * to retrieve touchscreen status. 241 * 242 * The SPI transfer completion callback does the real work. It reports 243 * touchscreen events and reactivates the timer (or IRQ) as appropriate. 244 */ 245 246 static void ads7846_rx(void *ads) 247 { 248 struct ads7846 *ts = ads; 249 struct input_dev *input_dev = ts->input; 250 unsigned Rt; 251 unsigned sync = 0; 252 u16 x, y, z1, z2; 253 unsigned long flags; 254 255 /* adjust: 12 bit samples (left aligned), built from 256 * two 8 bit values writen msb-first. 257 */ 258 x = be16_to_cpu(ts->tc.x) >> 4; 259 y = be16_to_cpu(ts->tc.y) >> 4; 260 z1 = be16_to_cpu(ts->tc.z1) >> 4; 261 z2 = be16_to_cpu(ts->tc.z2) >> 4; 262 263 /* range filtering */ 264 if (x == MAX_12BIT) 265 x = 0; 266 267 if (x && z1 && ts->spi->dev.power.power_state.event == PM_EVENT_ON) { 268 /* compute touch pressure resistance using equation #2 */ 269 Rt = z2; 270 Rt -= z1; 271 Rt *= x; 272 Rt *= ts->x_plate_ohms; 273 Rt /= z1; 274 Rt = (Rt + 2047) >> 12; 275 } else 276 Rt = 0; 277 278 /* NOTE: "pendown" is inferred from pressure; we don't rely on 279 * being able to check nPENIRQ status, or "friendly" trigger modes 280 * (both-edges is much better than just-falling or low-level). 281 * 282 * REVISIT: some boards may require reading nPENIRQ; it's 283 * needed on 7843. and 7845 reads pressure differently... 284 * 285 * REVISIT: the touchscreen might not be connected; this code 286 * won't notice that, even if nPENIRQ never fires ... 287 */ 288 if (!ts->pendown && Rt != 0) { 289 input_report_key(input_dev, BTN_TOUCH, 1); 290 sync = 1; 291 } else if (ts->pendown && Rt == 0) { 292 input_report_key(input_dev, BTN_TOUCH, 0); 293 sync = 1; 294 } 295 296 if (Rt) { 297 input_report_abs(input_dev, ABS_X, x); 298 input_report_abs(input_dev, ABS_Y, y); 299 input_report_abs(input_dev, ABS_PRESSURE, Rt); 300 sync = 1; 301 } 302 if (sync) 303 input_sync(input_dev); 304 305 #ifdef VERBOSE 306 if (Rt || ts->pendown) 307 pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id, 308 x, y, Rt, Rt ? "" : " UP"); 309 #endif 310 311 /* don't retrigger while we're suspended */ 312 spin_lock_irqsave(&ts->lock, flags); 313 314 ts->pendown = (Rt != 0); 315 ts->pending = 0; 316 317 if (ts->spi->dev.power.power_state.event == PM_EVENT_ON) { 318 if (ts->pendown) 319 mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD); 320 else if (ts->irq_disabled) { 321 ts->irq_disabled = 0; 322 enable_irq(ts->spi->irq); 323 } 324 } 325 326 spin_unlock_irqrestore(&ts->lock, flags); 327 } 328 329 static void ads7846_timer(unsigned long handle) 330 { 331 struct ads7846 *ts = (void *)handle; 332 int status = 0; 333 unsigned long flags; 334 335 spin_lock_irqsave(&ts->lock, flags); 336 if (!ts->pending) { 337 ts->pending = 1; 338 if (!ts->irq_disabled) { 339 ts->irq_disabled = 1; 340 disable_irq(ts->spi->irq); 341 } 342 status = spi_async(ts->spi, &ts->msg); 343 if (status) 344 dev_err(&ts->spi->dev, "spi_async --> %d\n", 345 status); 346 } 347 spin_unlock_irqrestore(&ts->lock, flags); 348 } 349 350 static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs) 351 { 352 ads7846_timer((unsigned long) handle); 353 return IRQ_HANDLED; 354 } 355 356 /*--------------------------------------------------------------------------*/ 357 358 static int 359 ads7846_suspend(struct spi_device *spi, pm_message_t message) 360 { 361 struct ads7846 *ts = dev_get_drvdata(&spi->dev); 362 unsigned long flags; 363 364 spin_lock_irqsave(&ts->lock, flags); 365 366 spi->dev.power.power_state = message; 367 368 /* are we waiting for IRQ, or polling? */ 369 if (!ts->pendown) { 370 if (!ts->irq_disabled) { 371 ts->irq_disabled = 1; 372 disable_irq(ts->spi->irq); 373 } 374 } else { 375 /* polling; force a final SPI completion; 376 * that will clean things up neatly 377 */ 378 if (!ts->pending) 379 mod_timer(&ts->timer, jiffies); 380 381 while (ts->pendown || ts->pending) { 382 spin_unlock_irqrestore(&ts->lock, flags); 383 udelay(10); 384 spin_lock_irqsave(&ts->lock, flags); 385 } 386 } 387 388 /* we know the chip's in lowpower mode since we always 389 * leave it that way after every request 390 */ 391 392 spin_unlock_irqrestore(&ts->lock, flags); 393 return 0; 394 } 395 396 static int ads7846_resume(struct spi_device *spi) 397 { 398 struct ads7846 *ts = dev_get_drvdata(&spi->dev); 399 400 ts->irq_disabled = 0; 401 enable_irq(ts->spi->irq); 402 spi->dev.power.power_state = PMSG_ON; 403 return 0; 404 } 405 406 static int __devinit ads7846_probe(struct spi_device *spi) 407 { 408 struct ads7846 *ts; 409 struct input_dev *input_dev; 410 struct ads7846_platform_data *pdata = spi->dev.platform_data; 411 struct spi_transfer *x; 412 int err; 413 414 if (!spi->irq) { 415 dev_dbg(&spi->dev, "no IRQ?\n"); 416 return -ENODEV; 417 } 418 419 if (!pdata) { 420 dev_dbg(&spi->dev, "no platform data?\n"); 421 return -ENODEV; 422 } 423 424 /* don't exceed max specified sample rate */ 425 if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { 426 dev_dbg(&spi->dev, "f(sample) %d KHz?\n", 427 (spi->max_speed_hz/SAMPLE_BITS)/1000); 428 return -EINVAL; 429 } 430 431 /* We'd set the wordsize to 12 bits ... except that some controllers 432 * will then treat the 8 bit command words as 12 bits (and drop the 433 * four MSBs of the 12 bit result). Result: inputs must be shifted 434 * to discard the four garbage LSBs. 435 */ 436 437 ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL); 438 input_dev = input_allocate_device(); 439 if (!ts || !input_dev) { 440 err = -ENOMEM; 441 goto err_free_mem; 442 } 443 444 dev_set_drvdata(&spi->dev, ts); 445 spi->dev.power.power_state = PMSG_ON; 446 447 ts->spi = spi; 448 ts->input = input_dev; 449 450 init_timer(&ts->timer); 451 ts->timer.data = (unsigned long) ts; 452 ts->timer.function = ads7846_timer; 453 454 ts->model = pdata->model ? : 7846; 455 ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100; 456 ts->x_plate_ohms = pdata->x_plate_ohms ? : 400; 457 458 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id); 459 460 input_dev->name = "ADS784x Touchscreen"; 461 input_dev->phys = ts->phys; 462 input_dev->cdev.dev = &spi->dev; 463 464 input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS); 465 input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH); 466 input_set_abs_params(input_dev, ABS_X, 467 pdata->x_min ? : 0, 468 pdata->x_max ? : MAX_12BIT, 469 0, 0); 470 input_set_abs_params(input_dev, ABS_Y, 471 pdata->y_min ? : 0, 472 pdata->y_max ? : MAX_12BIT, 473 0, 0); 474 input_set_abs_params(input_dev, ABS_PRESSURE, 475 pdata->pressure_min, pdata->pressure_max, 0, 0); 476 477 /* set up the transfers to read touchscreen state; this assumes we 478 * use formula #2 for pressure, not #3. 479 */ 480 INIT_LIST_HEAD(&ts->msg.transfers); 481 x = ts->xfer; 482 483 /* y- still on; turn on only y+ (and ADC) */ 484 ts->read_y = READ_Y; 485 x->tx_buf = &ts->read_y; 486 x->len = 1; 487 spi_message_add_tail(x, &ts->msg); 488 489 x++; 490 x->rx_buf = &ts->tc.y; 491 x->len = 2; 492 spi_message_add_tail(x, &ts->msg); 493 494 /* turn y+ off, x- on; we'll use formula #2 */ 495 if (ts->model == 7846) { 496 x++; 497 ts->read_z1 = READ_Z1; 498 x->tx_buf = &ts->read_z1; 499 x->len = 1; 500 spi_message_add_tail(x, &ts->msg); 501 502 x++; 503 x->rx_buf = &ts->tc.z1; 504 x->len = 2; 505 spi_message_add_tail(x, &ts->msg); 506 507 x++; 508 ts->read_z2 = READ_Z2; 509 x->tx_buf = &ts->read_z2; 510 x->len = 1; 511 spi_message_add_tail(x, &ts->msg); 512 513 x++; 514 x->rx_buf = &ts->tc.z2; 515 x->len = 2; 516 spi_message_add_tail(x, &ts->msg); 517 } 518 519 /* turn y- off, x+ on, then leave in lowpower */ 520 x++; 521 ts->read_x = READ_X; 522 x->tx_buf = &ts->read_x; 523 x->len = 1; 524 spi_message_add_tail(x, &ts->msg); 525 526 x++; 527 x->rx_buf = &ts->tc.x; 528 x->len = 2; 529 CS_CHANGE(*x); 530 spi_message_add_tail(x, &ts->msg); 531 532 ts->msg.complete = ads7846_rx; 533 ts->msg.context = ts; 534 535 if (request_irq(spi->irq, ads7846_irq, 536 SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING, 537 spi->dev.bus_id, ts)) { 538 dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq); 539 err = -EBUSY; 540 goto err_free_mem; 541 } 542 543 dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq); 544 545 /* take a first sample, leaving nPENIRQ active; avoid 546 * the touchscreen, in case it's not connected. 547 */ 548 (void) ads7846_read12_ser(&spi->dev, 549 READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON); 550 551 /* ads7843/7845 don't have temperature sensors, and 552 * use the other sensors a bit differently too 553 */ 554 if (ts->model == 7846) { 555 device_create_file(&spi->dev, &dev_attr_temp0); 556 device_create_file(&spi->dev, &dev_attr_temp1); 557 } 558 if (ts->model != 7845) 559 device_create_file(&spi->dev, &dev_attr_vbatt); 560 device_create_file(&spi->dev, &dev_attr_vaux); 561 562 err = input_register_device(input_dev); 563 if (err) 564 goto err_free_irq; 565 566 return 0; 567 568 err_free_irq: 569 free_irq(spi->irq, ts); 570 err_free_mem: 571 input_free_device(input_dev); 572 kfree(ts); 573 return err; 574 } 575 576 static int __devexit ads7846_remove(struct spi_device *spi) 577 { 578 struct ads7846 *ts = dev_get_drvdata(&spi->dev); 579 580 ads7846_suspend(spi, PMSG_SUSPEND); 581 free_irq(ts->spi->irq, ts); 582 if (ts->irq_disabled) 583 enable_irq(ts->spi->irq); 584 585 if (ts->model == 7846) { 586 device_remove_file(&spi->dev, &dev_attr_temp0); 587 device_remove_file(&spi->dev, &dev_attr_temp1); 588 } 589 if (ts->model != 7845) 590 device_remove_file(&spi->dev, &dev_attr_vbatt); 591 device_remove_file(&spi->dev, &dev_attr_vaux); 592 593 input_unregister_device(ts->input); 594 kfree(ts); 595 596 dev_dbg(&spi->dev, "unregistered touchscreen\n"); 597 return 0; 598 } 599 600 static struct spi_driver ads7846_driver = { 601 .driver = { 602 .name = "ads7846", 603 .bus = &spi_bus_type, 604 .owner = THIS_MODULE, 605 }, 606 .probe = ads7846_probe, 607 .remove = __devexit_p(ads7846_remove), 608 .suspend = ads7846_suspend, 609 .resume = ads7846_resume, 610 }; 611 612 static int __init ads7846_init(void) 613 { 614 /* grr, board-specific init should stay out of drivers!! */ 615 616 #ifdef CONFIG_ARCH_OMAP 617 if (machine_is_omap_osk()) { 618 /* GPIO4 = PENIRQ; GPIO6 = BUSY */ 619 omap_request_gpio(4); 620 omap_set_gpio_direction(4, 1); 621 omap_request_gpio(6); 622 omap_set_gpio_direction(6, 1); 623 } 624 // also TI 1510 Innovator, bitbanging through FPGA 625 // also Nokia 770 626 // also Palm Tungsten T2 627 #endif 628 629 // PXA: 630 // also Dell Axim X50 631 // also HP iPaq H191x/H192x/H415x/H435x 632 // also Intel Lubbock (additional to UCB1400; as temperature sensor) 633 // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky) 634 635 // Atmel at91sam9261-EK uses ads7843 636 637 // also various AMD Au1x00 devel boards 638 639 return spi_register_driver(&ads7846_driver); 640 } 641 module_init(ads7846_init); 642 643 static void __exit ads7846_exit(void) 644 { 645 spi_unregister_driver(&ads7846_driver); 646 647 #ifdef CONFIG_ARCH_OMAP 648 if (machine_is_omap_osk()) { 649 omap_free_gpio(4); 650 omap_free_gpio(6); 651 } 652 #endif 653 654 } 655 module_exit(ads7846_exit); 656 657 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver"); 658 MODULE_LICENSE("GPL"); 659