2 * ADS7846 based touchscreen and sensor driver
4 * Copyright (c) 2005 David Brownell
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
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.
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>
29 #include <asm/mach-types.h>
30 #ifdef CONFIG_ARCH_OMAP
31 #include <asm/arch/gpio.h>
37 * This code has been lightly tested on an ads7846.
38 * Support for ads7843 and ads7845 has only been stubbed in.
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.)
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.
50 #define TS_POLL_PERIOD msecs_to_jiffies(10)
52 /* this driver doesn't aim at the peak continuous sample rate */
53 #define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
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.
67 struct input_dev *input;
70 struct spi_device *spi;
75 u8 read_x, read_y, read_z1, read_z2;
78 struct spi_transfer xfer[8];
79 struct spi_message msg;
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 */
89 /* leave chip selected when we're done, for quicker re-select? */
91 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
93 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
96 /*--------------------------------------------------------------------------*/
98 /* The ADS7846 has touchscreen and other sensors.
99 * Earlier ads784x chips are somewhat compatible.
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 */
119 #define MAX_12BIT ((1<<12)-1)
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)
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 */
130 /* single-ended samples need to first power up reference voltage;
131 * we leave both ADC and VREF powered
133 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
134 | ADS_12_BIT | ADS_SER)
136 #define REF_ON (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
137 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
139 /*--------------------------------------------------------------------------*/
142 * Non-touchscreen sensors only use single-ended conversions.
151 struct spi_message msg;
152 struct spi_transfer xfer[6];
155 static int ads7846_read12_ser(struct device *dev, unsigned command)
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);
167 INIT_LIST_HEAD(&req->msg.transfers);
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;
177 * for external VREF, 0 usec (and assume it's always on);
178 * for 1uF, use 800 usec;
181 req->xfer[1].delay_usecs = ts->vref_delay_usecs;
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;
190 /* REVISIT: take a few more samples, and compare ... */
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;
199 CS_CHANGE(req->xfer[5]);
201 /* group all the transfers together, so we can't interfere with
202 * reading touchscreen state; disable penirq while sampling
204 for (i = 0; i < 6; i++)
205 spi_message_add_tail(&req->xfer[i], &req->msg);
207 disable_irq(spi->irq);
208 status = spi_sync(spi, &req->msg);
209 enable_irq(spi->irq);
212 status = req->msg.status;
213 sample = be16_to_cpu(req->sample);
214 sample = sample >> 4;
217 return status ? status : sample;
220 #define SHOW(name) static ssize_t \
221 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
223 ssize_t v = ads7846_read12_ser(dev, \
224 READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
227 return sprintf(buf, "%u\n", (unsigned) v); \
229 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
236 /*--------------------------------------------------------------------------*/
239 * PENIRQ only kicks the timer. The timer only reissues the SPI transfer,
240 * to retrieve touchscreen status.
242 * The SPI transfer completion callback does the real work. It reports
243 * touchscreen events and reactivates the timer (or IRQ) as appropriate.
246 static void ads7846_rx(void *ads)
248 struct ads7846 *ts = ads;
249 struct input_dev *input_dev = ts->input;
255 /* adjust: 12 bit samples (left aligned), built from
256 * two 8 bit values writen msb-first.
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;
263 /* range filtering */
267 if (x && z1 && ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
268 /* compute touch pressure resistance using equation #2 */
272 Rt *= ts->x_plate_ohms;
274 Rt = (Rt + 2047) >> 12;
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).
282 * REVISIT: some boards may require reading nPENIRQ; it's
283 * needed on 7843. and 7845 reads pressure differently...
285 * REVISIT: the touchscreen might not be connected; this code
286 * won't notice that, even if nPENIRQ never fires ...
288 if (!ts->pendown && Rt != 0) {
289 input_report_key(input_dev, BTN_TOUCH, 1);
291 } else if (ts->pendown && Rt == 0) {
292 input_report_key(input_dev, BTN_TOUCH, 0);
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);
303 input_sync(input_dev);
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");
311 /* don't retrigger while we're suspended */
312 spin_lock_irqsave(&ts->lock, flags);
314 ts->pendown = (Rt != 0);
317 if (ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
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);
326 spin_unlock_irqrestore(&ts->lock, flags);
329 static void ads7846_timer(unsigned long handle)
331 struct ads7846 *ts = (void *)handle;
335 spin_lock_irqsave(&ts->lock, flags);
338 if (!ts->irq_disabled) {
339 ts->irq_disabled = 1;
340 disable_irq(ts->spi->irq);
342 status = spi_async(ts->spi, &ts->msg);
344 dev_err(&ts->spi->dev, "spi_async --> %d\n",
347 spin_unlock_irqrestore(&ts->lock, flags);
350 static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
352 ads7846_timer((unsigned long) handle);
356 /*--------------------------------------------------------------------------*/
359 ads7846_suspend(struct spi_device *spi, pm_message_t message)
361 struct ads7846 *ts = dev_get_drvdata(&spi->dev);
364 spin_lock_irqsave(&ts->lock, flags);
366 spi->dev.power.power_state = message;
368 /* are we waiting for IRQ, or polling? */
370 if (!ts->irq_disabled) {
371 ts->irq_disabled = 1;
372 disable_irq(ts->spi->irq);
375 /* polling; force a final SPI completion;
376 * that will clean things up neatly
379 mod_timer(&ts->timer, jiffies);
381 while (ts->pendown || ts->pending) {
382 spin_unlock_irqrestore(&ts->lock, flags);
384 spin_lock_irqsave(&ts->lock, flags);
388 /* we know the chip's in lowpower mode since we always
389 * leave it that way after every request
392 spin_unlock_irqrestore(&ts->lock, flags);
396 static int ads7846_resume(struct spi_device *spi)
398 struct ads7846 *ts = dev_get_drvdata(&spi->dev);
400 ts->irq_disabled = 0;
401 enable_irq(ts->spi->irq);
402 spi->dev.power.power_state = PMSG_ON;
406 static int __devinit ads7846_probe(struct spi_device *spi)
409 struct input_dev *input_dev;
410 struct ads7846_platform_data *pdata = spi->dev.platform_data;
411 struct spi_transfer *x;
415 dev_dbg(&spi->dev, "no IRQ?\n");
420 dev_dbg(&spi->dev, "no platform data?\n");
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);
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.
437 ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
438 input_dev = input_allocate_device();
439 if (!ts || !input_dev) {
444 dev_set_drvdata(&spi->dev, ts);
445 spi->dev.power.power_state = PMSG_ON;
448 ts->input = input_dev;
450 init_timer(&ts->timer);
451 ts->timer.data = (unsigned long) ts;
452 ts->timer.function = ads7846_timer;
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;
458 snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
460 input_dev->name = "ADS784x Touchscreen";
461 input_dev->phys = ts->phys;
462 input_dev->cdev.dev = &spi->dev;
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,
468 pdata->x_max ? : MAX_12BIT,
470 input_set_abs_params(input_dev, ABS_Y,
472 pdata->y_max ? : MAX_12BIT,
474 input_set_abs_params(input_dev, ABS_PRESSURE,
475 pdata->pressure_min, pdata->pressure_max, 0, 0);
477 /* set up the transfers to read touchscreen state; this assumes we
478 * use formula #2 for pressure, not #3.
480 INIT_LIST_HEAD(&ts->msg.transfers);
483 /* y- still on; turn on only y+ (and ADC) */
485 x->tx_buf = &ts->read_y;
487 spi_message_add_tail(x, &ts->msg);
490 x->rx_buf = &ts->tc.y;
492 spi_message_add_tail(x, &ts->msg);
494 /* turn y+ off, x- on; we'll use formula #2 */
495 if (ts->model == 7846) {
497 ts->read_z1 = READ_Z1;
498 x->tx_buf = &ts->read_z1;
500 spi_message_add_tail(x, &ts->msg);
503 x->rx_buf = &ts->tc.z1;
505 spi_message_add_tail(x, &ts->msg);
508 ts->read_z2 = READ_Z2;
509 x->tx_buf = &ts->read_z2;
511 spi_message_add_tail(x, &ts->msg);
514 x->rx_buf = &ts->tc.z2;
516 spi_message_add_tail(x, &ts->msg);
519 /* turn y- off, x+ on, then leave in lowpower */
522 x->tx_buf = &ts->read_x;
524 spi_message_add_tail(x, &ts->msg);
527 x->rx_buf = &ts->tc.x;
530 spi_message_add_tail(x, &ts->msg);
532 ts->msg.complete = ads7846_rx;
533 ts->msg.context = ts;
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);
543 dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
545 /* take a first sample, leaving nPENIRQ active; avoid
546 * the touchscreen, in case it's not connected.
548 (void) ads7846_read12_ser(&spi->dev,
549 READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
551 /* ads7843/7845 don't have temperature sensors, and
552 * use the other sensors a bit differently too
554 if (ts->model == 7846) {
555 device_create_file(&spi->dev, &dev_attr_temp0);
556 device_create_file(&spi->dev, &dev_attr_temp1);
558 if (ts->model != 7845)
559 device_create_file(&spi->dev, &dev_attr_vbatt);
560 device_create_file(&spi->dev, &dev_attr_vaux);
562 err = input_register_device(input_dev);
569 free_irq(spi->irq, ts);
571 input_free_device(input_dev);
576 static int __devexit ads7846_remove(struct spi_device *spi)
578 struct ads7846 *ts = dev_get_drvdata(&spi->dev);
580 ads7846_suspend(spi, PMSG_SUSPEND);
581 free_irq(ts->spi->irq, ts);
582 if (ts->irq_disabled)
583 enable_irq(ts->spi->irq);
585 if (ts->model == 7846) {
586 device_remove_file(&spi->dev, &dev_attr_temp0);
587 device_remove_file(&spi->dev, &dev_attr_temp1);
589 if (ts->model != 7845)
590 device_remove_file(&spi->dev, &dev_attr_vbatt);
591 device_remove_file(&spi->dev, &dev_attr_vaux);
593 input_unregister_device(ts->input);
596 dev_dbg(&spi->dev, "unregistered touchscreen\n");
600 static struct spi_driver ads7846_driver = {
603 .bus = &spi_bus_type,
604 .owner = THIS_MODULE,
606 .probe = ads7846_probe,
607 .remove = __devexit_p(ads7846_remove),
608 .suspend = ads7846_suspend,
609 .resume = ads7846_resume,
612 static int __init ads7846_init(void)
614 /* grr, board-specific init should stay out of drivers!! */
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);
624 // also TI 1510 Innovator, bitbanging through FPGA
626 // also Palm Tungsten T2
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)
635 // Atmel at91sam9261-EK uses ads7843
637 // also various AMD Au1x00 devel boards
639 return spi_register_driver(&ads7846_driver);
641 module_init(ads7846_init);
643 static void __exit ads7846_exit(void)
645 spi_unregister_driver(&ads7846_driver);
647 #ifdef CONFIG_ARCH_OMAP
648 if (machine_is_omap_osk()) {
655 module_exit(ads7846_exit);
657 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
658 MODULE_LICENSE("GPL");