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>
28 #include <asm/mach-types.h>
29 #ifdef CONFIG_ARCH_OMAP
30 #include <asm/arch/gpio.h>
36 * This code has been lightly tested on an ads7846.
37 * Support for ads7843 and ads7845 has only been stubbed in.
39 * Not yet done: investigate the values reported. Are x/y/pressure
40 * event values sane enough for X11? How accurate are the temperature
41 * and voltage readings? (System-specific calibration should support
42 * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.)
44 * app note sbaa036 talks in more detail about accurate sampling...
45 * that ought to help in situations like LCDs inducing noise (which
46 * can also be helped by using synch signals) and more generally.
49 #define TS_POLL_PERIOD msecs_to_jiffies(10)
51 /* this driver doesn't aim at the peak continuous sample rate */
52 #define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
55 /* For portability, we can't read 12 bit values using SPI (which
56 * would make the controller deliver them as native byteorder u16
57 * with msbs zeroed). Instead, we read them as two 8-bit values,
58 * which need byteswapping then range adjustment.
66 struct input_dev
*input
;
69 struct spi_device
*spi
;
74 u8 read_x
, read_y
, read_z1
, read_z2
;
77 struct spi_transfer xfer
[8];
78 struct spi_message msg
;
81 struct timer_list timer
; /* P: lock */
82 unsigned pendown
:1; /* P: lock */
83 unsigned pending
:1; /* P: lock */
84 // FIXME remove "irq_disabled"
85 unsigned irq_disabled
:1; /* P: lock */
88 /* leave chip selected when we're done, for quicker re-select? */
90 #define CS_CHANGE(xfer) ((xfer).cs_change = 1)
92 #define CS_CHANGE(xfer) ((xfer).cs_change = 0)
95 /*--------------------------------------------------------------------------*/
97 /* The ADS7846 has touchscreen and other sensors.
98 * Earlier ads784x chips are somewhat compatible.
100 #define ADS_START (1 << 7)
101 #define ADS_A2A1A0_d_y (1 << 4) /* differential */
102 #define ADS_A2A1A0_d_z1 (3 << 4) /* differential */
103 #define ADS_A2A1A0_d_z2 (4 << 4) /* differential */
104 #define ADS_A2A1A0_d_x (5 << 4) /* differential */
105 #define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */
106 #define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */
107 #define ADS_A2A1A0_vaux (6 << 4) /* non-differential */
108 #define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */
109 #define ADS_8_BIT (1 << 3)
110 #define ADS_12_BIT (0 << 3)
111 #define ADS_SER (1 << 2) /* non-differential */
112 #define ADS_DFR (0 << 2) /* differential */
113 #define ADS_PD10_PDOWN (0 << 0) /* lowpower mode + penirq */
114 #define ADS_PD10_ADC_ON (1 << 0) /* ADC on */
115 #define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */
116 #define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */
118 #define MAX_12BIT ((1<<12)-1)
120 /* leave ADC powered up (disables penirq) between differential samples */
121 #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
122 | ADS_12_BIT | ADS_DFR)
124 #define READ_Y (READ_12BIT_DFR(y) | ADS_PD10_ADC_ON)
125 #define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
126 #define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
127 #define READ_X (READ_12BIT_DFR(x) | ADS_PD10_PDOWN) /* LAST */
129 /* single-ended samples need to first power up reference voltage;
130 * we leave both ADC and VREF powered
132 #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
133 | ADS_12_BIT | ADS_SER)
135 #define REF_ON (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
136 #define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
138 /*--------------------------------------------------------------------------*/
141 * Non-touchscreen sensors only use single-ended conversions.
150 struct spi_message msg
;
151 struct spi_transfer xfer
[6];
154 static int ads7846_read12_ser(struct device
*dev
, unsigned command
)
156 struct spi_device
*spi
= to_spi_device(dev
);
157 struct ads7846
*ts
= dev_get_drvdata(dev
);
158 struct ser_req
*req
= kzalloc(sizeof *req
, SLAB_KERNEL
);
166 INIT_LIST_HEAD(&req
->msg
.transfers
);
168 /* activate reference, so it has time to settle; */
169 req
->ref_on
= REF_ON
;
170 req
->xfer
[0].tx_buf
= &req
->ref_on
;
171 req
->xfer
[0].len
= 1;
172 req
->xfer
[1].rx_buf
= &req
->scratch
;
173 req
->xfer
[1].len
= 2;
176 * for external VREF, 0 usec (and assume it's always on);
177 * for 1uF, use 800 usec;
180 req
->xfer
[1].delay_usecs
= ts
->vref_delay_usecs
;
183 req
->command
= (u8
) command
;
184 req
->xfer
[2].tx_buf
= &req
->command
;
185 req
->xfer
[2].len
= 1;
186 req
->xfer
[3].rx_buf
= &req
->sample
;
187 req
->xfer
[3].len
= 2;
189 /* REVISIT: take a few more samples, and compare ... */
191 /* turn off reference */
192 req
->ref_off
= REF_OFF
;
193 req
->xfer
[4].tx_buf
= &req
->ref_off
;
194 req
->xfer
[4].len
= 1;
195 req
->xfer
[5].rx_buf
= &req
->scratch
;
196 req
->xfer
[5].len
= 2;
198 CS_CHANGE(req
->xfer
[5]);
200 /* group all the transfers together, so we can't interfere with
201 * reading touchscreen state; disable penirq while sampling
203 for (i
= 0; i
< 6; i
++)
204 spi_message_add_tail(&req
->xfer
[i
], &req
->msg
);
206 disable_irq(spi
->irq
);
207 status
= spi_sync(spi
, &req
->msg
);
208 enable_irq(spi
->irq
);
211 status
= req
->msg
.status
;
212 sample
= be16_to_cpu(req
->sample
);
213 sample
= sample
>> 4;
216 return status
? status
: sample
;
219 #define SHOW(name) static ssize_t \
220 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
222 ssize_t v = ads7846_read12_ser(dev, \
223 READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
226 return sprintf(buf, "%u\n", (unsigned) v); \
228 static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
235 /*--------------------------------------------------------------------------*/
238 * PENIRQ only kicks the timer. The timer only reissues the SPI transfer,
239 * to retrieve touchscreen status.
241 * The SPI transfer completion callback does the real work. It reports
242 * touchscreen events and reactivates the timer (or IRQ) as appropriate.
245 static void ads7846_rx(void *ads
)
247 struct ads7846
*ts
= ads
;
248 struct input_dev
*input_dev
= ts
->input
;
254 /* adjust: 12 bit samples (left aligned), built from
255 * two 8 bit values writen msb-first.
257 x
= be16_to_cpu(ts
->tc
.x
) >> 4;
258 y
= be16_to_cpu(ts
->tc
.y
) >> 4;
259 z1
= be16_to_cpu(ts
->tc
.z1
) >> 4;
260 z2
= be16_to_cpu(ts
->tc
.z2
) >> 4;
262 /* range filtering */
266 if (x
&& z1
&& ts
->spi
->dev
.power
.power_state
.event
== PM_EVENT_ON
) {
267 /* compute touch pressure resistance using equation #2 */
271 Rt
*= ts
->x_plate_ohms
;
273 Rt
= (Rt
+ 2047) >> 12;
277 /* NOTE: "pendown" is inferred from pressure; we don't rely on
278 * being able to check nPENIRQ status, or "friendly" trigger modes
279 * (both-edges is much better than just-falling or low-level).
281 * REVISIT: some boards may require reading nPENIRQ; it's
282 * needed on 7843. and 7845 reads pressure differently...
284 * REVISIT: the touchscreen might not be connected; this code
285 * won't notice that, even if nPENIRQ never fires ...
287 if (!ts
->pendown
&& Rt
!= 0) {
288 input_report_key(input_dev
, BTN_TOUCH
, 1);
290 } else if (ts
->pendown
&& Rt
== 0) {
291 input_report_key(input_dev
, BTN_TOUCH
, 0);
296 input_report_abs(input_dev
, ABS_X
, x
);
297 input_report_abs(input_dev
, ABS_Y
, y
);
298 input_report_abs(input_dev
, ABS_PRESSURE
, Rt
);
302 input_sync(input_dev
);
305 if (Rt
|| ts
->pendown
)
306 pr_debug("%s: %d/%d/%d%s\n", ts
->spi
->dev
.bus_id
,
307 x
, y
, Rt
, Rt
? "" : " UP");
310 /* don't retrigger while we're suspended */
311 spin_lock_irqsave(&ts
->lock
, flags
);
313 ts
->pendown
= (Rt
!= 0);
316 if (ts
->spi
->dev
.power
.power_state
.event
== PM_EVENT_ON
) {
318 mod_timer(&ts
->timer
, jiffies
+ TS_POLL_PERIOD
);
319 else if (ts
->irq_disabled
) {
320 ts
->irq_disabled
= 0;
321 enable_irq(ts
->spi
->irq
);
325 spin_unlock_irqrestore(&ts
->lock
, flags
);
328 static void ads7846_timer(unsigned long handle
)
330 struct ads7846
*ts
= (void *)handle
;
334 spin_lock_irqsave(&ts
->lock
, flags
);
337 if (!ts
->irq_disabled
) {
338 ts
->irq_disabled
= 1;
339 disable_irq(ts
->spi
->irq
);
341 status
= spi_async(ts
->spi
, &ts
->msg
);
343 dev_err(&ts
->spi
->dev
, "spi_async --> %d\n",
346 spin_unlock_irqrestore(&ts
->lock
, flags
);
349 static irqreturn_t
ads7846_irq(int irq
, void *handle
, struct pt_regs
*regs
)
351 ads7846_timer((unsigned long) handle
);
355 /*--------------------------------------------------------------------------*/
358 ads7846_suspend(struct spi_device
*spi
, pm_message_t message
)
360 struct ads7846
*ts
= dev_get_drvdata(&spi
->dev
);
363 spin_lock_irqsave(&ts
->lock
, flags
);
365 spi
->dev
.power
.power_state
= message
;
367 /* are we waiting for IRQ, or polling? */
369 if (!ts
->irq_disabled
) {
370 ts
->irq_disabled
= 1;
371 disable_irq(ts
->spi
->irq
);
374 /* polling; force a final SPI completion;
375 * that will clean things up neatly
378 mod_timer(&ts
->timer
, jiffies
);
380 while (ts
->pendown
|| ts
->pending
) {
381 spin_unlock_irqrestore(&ts
->lock
, flags
);
383 spin_lock_irqsave(&ts
->lock
, flags
);
387 /* we know the chip's in lowpower mode since we always
388 * leave it that way after every request
391 spin_unlock_irqrestore(&ts
->lock
, flags
);
395 static int ads7846_resume(struct spi_device
*spi
)
397 struct ads7846
*ts
= dev_get_drvdata(&spi
->dev
);
399 ts
->irq_disabled
= 0;
400 enable_irq(ts
->spi
->irq
);
401 spi
->dev
.power
.power_state
= PMSG_ON
;
405 static int __devinit
ads7846_probe(struct spi_device
*spi
)
408 struct input_dev
*input_dev
;
409 struct ads7846_platform_data
*pdata
= spi
->dev
.platform_data
;
410 struct spi_transfer
*x
;
414 dev_dbg(&spi
->dev
, "no IRQ?\n");
419 dev_dbg(&spi
->dev
, "no platform data?\n");
423 /* don't exceed max specified sample rate */
424 if (spi
->max_speed_hz
> (125000 * SAMPLE_BITS
)) {
425 dev_dbg(&spi
->dev
, "f(sample) %d KHz?\n",
426 (spi
->max_speed_hz
/SAMPLE_BITS
)/1000);
430 /* We'd set the wordsize to 12 bits ... except that some controllers
431 * will then treat the 8 bit command words as 12 bits (and drop the
432 * four MSBs of the 12 bit result). Result: inputs must be shifted
433 * to discard the four garbage LSBs.
436 ts
= kzalloc(sizeof(struct ads7846
), GFP_KERNEL
);
437 input_dev
= input_allocate_device();
438 if (!ts
|| !input_dev
) {
443 dev_set_drvdata(&spi
->dev
, ts
);
444 spi
->dev
.power
.power_state
= PMSG_ON
;
447 ts
->input
= input_dev
;
449 init_timer(&ts
->timer
);
450 ts
->timer
.data
= (unsigned long) ts
;
451 ts
->timer
.function
= ads7846_timer
;
453 ts
->model
= pdata
->model
? : 7846;
454 ts
->vref_delay_usecs
= pdata
->vref_delay_usecs
? : 100;
455 ts
->x_plate_ohms
= pdata
->x_plate_ohms
? : 400;
457 snprintf(ts
->phys
, sizeof(ts
->phys
), "%s/input0", spi
->dev
.bus_id
);
459 input_dev
->name
= "ADS784x Touchscreen";
460 input_dev
->phys
= ts
->phys
;
461 input_dev
->cdev
.dev
= &spi
->dev
;
463 input_dev
->evbit
[0] = BIT(EV_KEY
) | BIT(EV_ABS
);
464 input_dev
->keybit
[LONG(BTN_TOUCH
)] = BIT(BTN_TOUCH
);
465 input_set_abs_params(input_dev
, ABS_X
,
467 pdata
->x_max
? : MAX_12BIT
,
469 input_set_abs_params(input_dev
, ABS_Y
,
471 pdata
->y_max
? : MAX_12BIT
,
473 input_set_abs_params(input_dev
, ABS_PRESSURE
,
474 pdata
->pressure_min
, pdata
->pressure_max
, 0, 0);
476 /* set up the transfers to read touchscreen state; this assumes we
477 * use formula #2 for pressure, not #3.
479 INIT_LIST_HEAD(&ts
->msg
.transfers
);
482 /* y- still on; turn on only y+ (and ADC) */
484 x
->tx_buf
= &ts
->read_y
;
486 spi_message_add_tail(x
, &ts
->msg
);
489 x
->rx_buf
= &ts
->tc
.y
;
491 spi_message_add_tail(x
, &ts
->msg
);
493 /* turn y+ off, x- on; we'll use formula #2 */
494 if (ts
->model
== 7846) {
496 ts
->read_z1
= READ_Z1
;
497 x
->tx_buf
= &ts
->read_z1
;
499 spi_message_add_tail(x
, &ts
->msg
);
502 x
->rx_buf
= &ts
->tc
.z1
;
504 spi_message_add_tail(x
, &ts
->msg
);
507 ts
->read_z2
= READ_Z2
;
508 x
->tx_buf
= &ts
->read_z2
;
510 spi_message_add_tail(x
, &ts
->msg
);
513 x
->rx_buf
= &ts
->tc
.z2
;
515 spi_message_add_tail(x
, &ts
->msg
);
518 /* turn y- off, x+ on, then leave in lowpower */
521 x
->tx_buf
= &ts
->read_x
;
523 spi_message_add_tail(x
, &ts
->msg
);
526 x
->rx_buf
= &ts
->tc
.x
;
529 spi_message_add_tail(x
, &ts
->msg
);
531 ts
->msg
.complete
= ads7846_rx
;
532 ts
->msg
.context
= ts
;
534 if (request_irq(spi
->irq
, ads7846_irq
,
535 SA_SAMPLE_RANDOM
| SA_TRIGGER_FALLING
,
536 spi
->dev
.bus_id
, ts
)) {
537 dev_dbg(&spi
->dev
, "irq %d busy?\n", spi
->irq
);
542 dev_info(&spi
->dev
, "touchscreen, irq %d\n", spi
->irq
);
544 /* take a first sample, leaving nPENIRQ active; avoid
545 * the touchscreen, in case it's not connected.
547 (void) ads7846_read12_ser(&spi
->dev
,
548 READ_12BIT_SER(vaux
) | ADS_PD10_ALL_ON
);
550 /* ads7843/7845 don't have temperature sensors, and
551 * use the other sensors a bit differently too
553 if (ts
->model
== 7846) {
554 device_create_file(&spi
->dev
, &dev_attr_temp0
);
555 device_create_file(&spi
->dev
, &dev_attr_temp1
);
557 if (ts
->model
!= 7845)
558 device_create_file(&spi
->dev
, &dev_attr_vbatt
);
559 device_create_file(&spi
->dev
, &dev_attr_vaux
);
561 err
= input_register_device(input_dev
);
568 free_irq(spi
->irq
, ts
);
570 input_free_device(input_dev
);
575 static int __devexit
ads7846_remove(struct spi_device
*spi
)
577 struct ads7846
*ts
= dev_get_drvdata(&spi
->dev
);
579 ads7846_suspend(spi
, PMSG_SUSPEND
);
580 free_irq(ts
->spi
->irq
, ts
);
581 if (ts
->irq_disabled
)
582 enable_irq(ts
->spi
->irq
);
584 if (ts
->model
== 7846) {
585 device_remove_file(&spi
->dev
, &dev_attr_temp0
);
586 device_remove_file(&spi
->dev
, &dev_attr_temp1
);
588 if (ts
->model
!= 7845)
589 device_remove_file(&spi
->dev
, &dev_attr_vbatt
);
590 device_remove_file(&spi
->dev
, &dev_attr_vaux
);
592 input_unregister_device(ts
->input
);
595 dev_dbg(&spi
->dev
, "unregistered touchscreen\n");
599 static struct spi_driver ads7846_driver
= {
602 .bus
= &spi_bus_type
,
603 .owner
= THIS_MODULE
,
605 .probe
= ads7846_probe
,
606 .remove
= __devexit_p(ads7846_remove
),
607 .suspend
= ads7846_suspend
,
608 .resume
= ads7846_resume
,
611 static int __init
ads7846_init(void)
613 /* grr, board-specific init should stay out of drivers!! */
615 #ifdef CONFIG_ARCH_OMAP
616 if (machine_is_omap_osk()) {
617 /* GPIO4 = PENIRQ; GPIO6 = BUSY */
618 omap_request_gpio(4);
619 omap_set_gpio_direction(4, 1);
620 omap_request_gpio(6);
621 omap_set_gpio_direction(6, 1);
623 // also TI 1510 Innovator, bitbanging through FPGA
625 // also Palm Tungsten T2
629 // also Dell Axim X50
630 // also HP iPaq H191x/H192x/H415x/H435x
631 // also Intel Lubbock (additional to UCB1400; as temperature sensor)
632 // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
634 // Atmel at91sam9261-EK uses ads7843
636 // also various AMD Au1x00 devel boards
638 return spi_register_driver(&ads7846_driver
);
640 module_init(ads7846_init
);
642 static void __exit
ads7846_exit(void)
644 spi_unregister_driver(&ads7846_driver
);
646 #ifdef CONFIG_ARCH_OMAP
647 if (machine_is_omap_osk()) {
654 module_exit(ads7846_exit
);
656 MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
657 MODULE_LICENSE("GPL");