linux/drivers/input/touchscreen/ads7846.c
Jason Wang 2991a1ca6e Input: ads7846 - switch to using threaded IRQ
Commit 9114337 introduces regulator operations in ads7846 touchscreen
driver. Among these operations, some are called while holding a
spinlock. On many platforms regulators reside on slow buses, such as
I2C/SPI and require sleep while accessing them.

The touchscreen itself is also a SPI device and currently relies on
asynchronous SPI access to avoid sleeping in interrupt context. Let's
switch to using threaded IRQ to be able to access SPI bus
synchronously (which simplifies driver a bit); it also allows safe
access to the regulators as well.

This has been tested on the ti_omap3530evm board:
 1) using ts_lib after normal boot
 2) using ts_lib after "#echo 1/0 > /sys/bus/spi/devices/spi0.1/disable"
 3) using ts_lib after "#echo mem > /sys/power/state" and "wake up"

Also tested on pandora.

Based on original patch by Dmitry Torokhov.

Tested-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Jason Wang <jason77.wang@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-10-17 21:10:28 -07:00

1427 lines
33 KiB
C

/*
* ADS7846 based touchscreen and sensor driver
*
* Copyright (c) 2005 David Brownell
* Copyright (c) 2006 Nokia Corporation
* Various changes: Imre Deak <imre.deak@nokia.com>
*
* Using code from:
* - corgi_ts.c
* Copyright (C) 2004-2005 Richard Purdie
* - omap_ts.[hc], ads7846.h, ts_osk.c
* Copyright (C) 2002 MontaVista Software
* Copyright (C) 2004 Texas Instruments
* Copyright (C) 2005 Dirk Behme
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/types.h>
#include <linux/hwmon.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/gpio.h>
#include <linux/spi/spi.h>
#include <linux/spi/ads7846.h>
#include <linux/regulator/consumer.h>
#include <asm/irq.h>
/*
* This code has been heavily tested on a Nokia 770, and lightly
* tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
* TSC2046 is just newer ads7846 silicon.
* Support for ads7843 tested on Atmel at91sam926x-EK.
* Support for ads7845 has only been stubbed in.
* Support for Analog Devices AD7873 and AD7843 tested.
*
* IRQ handling needs a workaround because of a shortcoming in handling
* edge triggered IRQs on some platforms like the OMAP1/2. These
* platforms don't handle the ARM lazy IRQ disabling properly, thus we
* have to maintain our own SW IRQ disabled status. This should be
* removed as soon as the affected platform's IRQ handling is fixed.
*
* App note sbaa036 talks in more detail about accurate sampling...
* that ought to help in situations like LCDs inducing noise (which
* can also be helped by using synch signals) and more generally.
* This driver tries to utilize the measures described in the app
* note. The strength of filtering can be set in the board-* specific
* files.
*/
#define TS_POLL_DELAY 1 /* ms delay before the first sample */
#define TS_POLL_PERIOD 5 /* ms delay between samples */
/* this driver doesn't aim at the peak continuous sample rate */
#define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
struct ts_event {
/*
* For portability, we can't read 12 bit values using SPI (which
* would make the controller deliver them as native byte order u16
* with msbs zeroed). Instead, we read them as two 8-bit values,
* *** WHICH NEED BYTESWAPPING *** and range adjustment.
*/
u16 x;
u16 y;
u16 z1, z2;
bool ignore;
u8 x_buf[3];
u8 y_buf[3];
};
/*
* We allocate this separately to avoid cache line sharing issues when
* driver is used with DMA-based SPI controllers (like atmel_spi) on
* systems where main memory is not DMA-coherent (most non-x86 boards).
*/
struct ads7846_packet {
u8 read_x, read_y, read_z1, read_z2, pwrdown;
u16 dummy; /* for the pwrdown read */
struct ts_event tc;
/* for ads7845 with mpc5121 psc spi we use 3-byte buffers */
u8 read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3];
};
struct ads7846 {
struct input_dev *input;
char phys[32];
char name[32];
struct spi_device *spi;
struct regulator *reg;
#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
struct attribute_group *attr_group;
struct device *hwmon;
#endif
u16 model;
u16 vref_mv;
u16 vref_delay_usecs;
u16 x_plate_ohms;
u16 pressure_max;
bool swap_xy;
struct ads7846_packet *packet;
struct spi_transfer xfer[18];
struct spi_message msg[5];
int msg_count;
wait_queue_head_t wait;
bool pendown;
int read_cnt;
int read_rep;
int last_read;
u16 debounce_max;
u16 debounce_tol;
u16 debounce_rep;
u16 penirq_recheck_delay_usecs;
struct mutex lock;
bool stopped; /* P: lock */
bool disabled; /* P: lock */
bool suspended; /* P: lock */
int (*filter)(void *data, int data_idx, int *val);
void *filter_data;
void (*filter_cleanup)(void *data);
int (*get_pendown_state)(void);
int gpio_pendown;
void (*wait_for_sync)(void);
};
/* leave chip selected when we're done, for quicker re-select? */
#if 0
#define CS_CHANGE(xfer) ((xfer).cs_change = 1)
#else
#define CS_CHANGE(xfer) ((xfer).cs_change = 0)
#endif
/*--------------------------------------------------------------------------*/
/* The ADS7846 has touchscreen and other sensors.
* Earlier ads784x chips are somewhat compatible.
*/
#define ADS_START (1 << 7)
#define ADS_A2A1A0_d_y (1 << 4) /* differential */
#define ADS_A2A1A0_d_z1 (3 << 4) /* differential */
#define ADS_A2A1A0_d_z2 (4 << 4) /* differential */
#define ADS_A2A1A0_d_x (5 << 4) /* differential */
#define ADS_A2A1A0_temp0 (0 << 4) /* non-differential */
#define ADS_A2A1A0_vbatt (2 << 4) /* non-differential */
#define ADS_A2A1A0_vaux (6 << 4) /* non-differential */
#define ADS_A2A1A0_temp1 (7 << 4) /* non-differential */
#define ADS_8_BIT (1 << 3)
#define ADS_12_BIT (0 << 3)
#define ADS_SER (1 << 2) /* non-differential */
#define ADS_DFR (0 << 2) /* differential */
#define ADS_PD10_PDOWN (0 << 0) /* low power mode + penirq */
#define ADS_PD10_ADC_ON (1 << 0) /* ADC on */
#define ADS_PD10_REF_ON (2 << 0) /* vREF on + penirq */
#define ADS_PD10_ALL_ON (3 << 0) /* ADC + vREF on */
#define MAX_12BIT ((1<<12)-1)
/* leave ADC powered up (disables penirq) between differential samples */
#define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
| ADS_12_BIT | ADS_DFR | \
(adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
#define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref))
#define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref))
#define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref))
#define READ_X(vref) (READ_12BIT_DFR(x, 1, vref))
#define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */
/* single-ended samples need to first power up reference voltage;
* we leave both ADC and VREF powered
*/
#define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
| ADS_12_BIT | ADS_SER)
#define REF_ON (READ_12BIT_DFR(x, 1, 1))
#define REF_OFF (READ_12BIT_DFR(y, 0, 0))
/* Must be called with ts->lock held */
static void ads7846_stop(struct ads7846 *ts)
{
if (!ts->disabled && !ts->suspended) {
/* Signal IRQ thread to stop polling and disable the handler. */
ts->stopped = true;
mb();
wake_up(&ts->wait);
disable_irq(ts->spi->irq);
}
}
/* Must be called with ts->lock held */
static void ads7846_restart(struct ads7846 *ts)
{
if (!ts->disabled && !ts->suspended) {
/* Tell IRQ thread that it may poll the device. */
ts->stopped = false;
mb();
enable_irq(ts->spi->irq);
}
}
/* Must be called with ts->lock held */
static void __ads7846_disable(struct ads7846 *ts)
{
ads7846_stop(ts);
regulator_disable(ts->reg);
/*
* We know the chip's in low power mode since we always
* leave it that way after every request
*/
}
/* Must be called with ts->lock held */
static void __ads7846_enable(struct ads7846 *ts)
{
regulator_enable(ts->reg);
ads7846_restart(ts);
}
static void ads7846_disable(struct ads7846 *ts)
{
mutex_lock(&ts->lock);
if (!ts->disabled) {
if (!ts->suspended)
__ads7846_disable(ts);
ts->disabled = true;
}
mutex_unlock(&ts->lock);
}
static void ads7846_enable(struct ads7846 *ts)
{
mutex_lock(&ts->lock);
if (ts->disabled) {
ts->disabled = false;
if (!ts->suspended)
__ads7846_enable(ts);
}
mutex_unlock(&ts->lock);
}
/*--------------------------------------------------------------------------*/
/*
* Non-touchscreen sensors only use single-ended conversions.
* The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
* ads7846 lets that pin be unconnected, to use internal vREF.
*/
struct ser_req {
u8 ref_on;
u8 command;
u8 ref_off;
u16 scratch;
__be16 sample;
struct spi_message msg;
struct spi_transfer xfer[6];
};
struct ads7845_ser_req {
u8 command[3];
u8 pwrdown[3];
u8 sample[3];
struct spi_message msg;
struct spi_transfer xfer[2];
};
static int ads7846_read12_ser(struct device *dev, unsigned command)
{
struct spi_device *spi = to_spi_device(dev);
struct ads7846 *ts = dev_get_drvdata(dev);
struct ser_req *req;
int status;
int use_internal;
req = kzalloc(sizeof *req, GFP_KERNEL);
if (!req)
return -ENOMEM;
spi_message_init(&req->msg);
/* FIXME boards with ads7846 might use external vref instead ... */
use_internal = (ts->model == 7846);
/* maybe turn on internal vREF, and let it settle */
if (use_internal) {
req->ref_on = REF_ON;
req->xfer[0].tx_buf = &req->ref_on;
req->xfer[0].len = 1;
spi_message_add_tail(&req->xfer[0], &req->msg);
req->xfer[1].rx_buf = &req->scratch;
req->xfer[1].len = 2;
/* for 1uF, settle for 800 usec; no cap, 100 usec. */
req->xfer[1].delay_usecs = ts->vref_delay_usecs;
spi_message_add_tail(&req->xfer[1], &req->msg);
}
/* take sample */
req->command = (u8) command;
req->xfer[2].tx_buf = &req->command;
req->xfer[2].len = 1;
spi_message_add_tail(&req->xfer[2], &req->msg);
req->xfer[3].rx_buf = &req->sample;
req->xfer[3].len = 2;
spi_message_add_tail(&req->xfer[3], &req->msg);
/* REVISIT: take a few more samples, and compare ... */
/* converter in low power mode & enable PENIRQ */
req->ref_off = PWRDOWN;
req->xfer[4].tx_buf = &req->ref_off;
req->xfer[4].len = 1;
spi_message_add_tail(&req->xfer[4], &req->msg);
req->xfer[5].rx_buf = &req->scratch;
req->xfer[5].len = 2;
CS_CHANGE(req->xfer[5]);
spi_message_add_tail(&req->xfer[5], &req->msg);
mutex_lock(&ts->lock);
ads7846_stop(ts);
status = spi_sync(spi, &req->msg);
ads7846_restart(ts);
mutex_unlock(&ts->lock);
if (status == 0) {
/* on-wire is a must-ignore bit, a BE12 value, then padding */
status = be16_to_cpu(req->sample);
status = status >> 3;
status &= 0x0fff;
}
kfree(req);
return status;
}
static int ads7845_read12_ser(struct device *dev, unsigned command)
{
struct spi_device *spi = to_spi_device(dev);
struct ads7846 *ts = dev_get_drvdata(dev);
struct ads7845_ser_req *req;
int status;
req = kzalloc(sizeof *req, GFP_KERNEL);
if (!req)
return -ENOMEM;
spi_message_init(&req->msg);
req->command[0] = (u8) command;
req->xfer[0].tx_buf = req->command;
req->xfer[0].rx_buf = req->sample;
req->xfer[0].len = 3;
spi_message_add_tail(&req->xfer[0], &req->msg);
mutex_lock(&ts->lock);
ads7846_stop(ts);
status = spi_sync(spi, &req->msg);
ads7846_restart(ts);
mutex_unlock(&ts->lock);
if (status == 0) {
/* BE12 value, then padding */
status = be16_to_cpu(*((u16 *)&req->sample[1]));
status = status >> 3;
status &= 0x0fff;
}
kfree(req);
return status;
}
#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
#define SHOW(name, var, adjust) static ssize_t \
name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
{ \
struct ads7846 *ts = dev_get_drvdata(dev); \
ssize_t v = ads7846_read12_ser(dev, \
READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
if (v < 0) \
return v; \
return sprintf(buf, "%u\n", adjust(ts, v)); \
} \
static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
/* Sysfs conventions report temperatures in millidegrees Celsius.
* ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
* accuracy scheme without calibration data. For now we won't try either;
* userspace sees raw sensor values, and must scale/calibrate appropriately.
*/
static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
{
return v;
}
SHOW(temp0, temp0, null_adjust) /* temp1_input */
SHOW(temp1, temp1, null_adjust) /* temp2_input */
/* sysfs conventions report voltages in millivolts. We can convert voltages
* if we know vREF. userspace may need to scale vAUX to match the board's
* external resistors; we assume that vBATT only uses the internal ones.
*/
static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
{
unsigned retval = v;
/* external resistors may scale vAUX into 0..vREF */
retval *= ts->vref_mv;
retval = retval >> 12;
return retval;
}
static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
{
unsigned retval = vaux_adjust(ts, v);
/* ads7846 has a resistor ladder to scale this signal down */
if (ts->model == 7846)
retval *= 4;
return retval;
}
SHOW(in0_input, vaux, vaux_adjust)
SHOW(in1_input, vbatt, vbatt_adjust)
static struct attribute *ads7846_attributes[] = {
&dev_attr_temp0.attr,
&dev_attr_temp1.attr,
&dev_attr_in0_input.attr,
&dev_attr_in1_input.attr,
NULL,
};
static struct attribute_group ads7846_attr_group = {
.attrs = ads7846_attributes,
};
static struct attribute *ads7843_attributes[] = {
&dev_attr_in0_input.attr,
&dev_attr_in1_input.attr,
NULL,
};
static struct attribute_group ads7843_attr_group = {
.attrs = ads7843_attributes,
};
static struct attribute *ads7845_attributes[] = {
&dev_attr_in0_input.attr,
NULL,
};
static struct attribute_group ads7845_attr_group = {
.attrs = ads7845_attributes,
};
static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
{
struct device *hwmon;
int err;
/* hwmon sensors need a reference voltage */
switch (ts->model) {
case 7846:
if (!ts->vref_mv) {
dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
ts->vref_mv = 2500;
}
break;
case 7845:
case 7843:
if (!ts->vref_mv) {
dev_warn(&spi->dev,
"external vREF for ADS%d not specified\n",
ts->model);
return 0;
}
break;
}
/* different chips have different sensor groups */
switch (ts->model) {
case 7846:
ts->attr_group = &ads7846_attr_group;
break;
case 7845:
ts->attr_group = &ads7845_attr_group;
break;
case 7843:
ts->attr_group = &ads7843_attr_group;
break;
default:
dev_dbg(&spi->dev, "ADS%d not recognized\n", ts->model);
return 0;
}
err = sysfs_create_group(&spi->dev.kobj, ts->attr_group);
if (err)
return err;
hwmon = hwmon_device_register(&spi->dev);
if (IS_ERR(hwmon)) {
sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
return PTR_ERR(hwmon);
}
ts->hwmon = hwmon;
return 0;
}
static void ads784x_hwmon_unregister(struct spi_device *spi,
struct ads7846 *ts)
{
if (ts->hwmon) {
sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
hwmon_device_unregister(ts->hwmon);
}
}
#else
static inline int ads784x_hwmon_register(struct spi_device *spi,
struct ads7846 *ts)
{
return 0;
}
static inline void ads784x_hwmon_unregister(struct spi_device *spi,
struct ads7846 *ts)
{
}
#endif
static ssize_t ads7846_pen_down_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ads7846 *ts = dev_get_drvdata(dev);
return sprintf(buf, "%u\n", ts->pendown);
}
static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
static ssize_t ads7846_disable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ads7846 *ts = dev_get_drvdata(dev);
return sprintf(buf, "%u\n", ts->disabled);
}
static ssize_t ads7846_disable_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct ads7846 *ts = dev_get_drvdata(dev);
unsigned long i;
if (strict_strtoul(buf, 10, &i))
return -EINVAL;
if (i)
ads7846_disable(ts);
else
ads7846_enable(ts);
return count;
}
static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
static struct attribute *ads784x_attributes[] = {
&dev_attr_pen_down.attr,
&dev_attr_disable.attr,
NULL,
};
static struct attribute_group ads784x_attr_group = {
.attrs = ads784x_attributes,
};
/*--------------------------------------------------------------------------*/
static int get_pendown_state(struct ads7846 *ts)
{
if (ts->get_pendown_state)
return ts->get_pendown_state();
return !gpio_get_value(ts->gpio_pendown);
}
static void null_wait_for_sync(void)
{
}
static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
{
struct ads7846 *ts = ads;
if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
/* Start over collecting consistent readings. */
ts->read_rep = 0;
/*
* Repeat it, if this was the first read or the read
* wasn't consistent enough.
*/
if (ts->read_cnt < ts->debounce_max) {
ts->last_read = *val;
ts->read_cnt++;
return ADS7846_FILTER_REPEAT;
} else {
/*
* Maximum number of debouncing reached and still
* not enough number of consistent readings. Abort
* the whole sample, repeat it in the next sampling
* period.
*/
ts->read_cnt = 0;
return ADS7846_FILTER_IGNORE;
}
} else {
if (++ts->read_rep > ts->debounce_rep) {
/*
* Got a good reading for this coordinate,
* go for the next one.
*/
ts->read_cnt = 0;
ts->read_rep = 0;
return ADS7846_FILTER_OK;
} else {
/* Read more values that are consistent. */
ts->read_cnt++;
return ADS7846_FILTER_REPEAT;
}
}
}
static int ads7846_no_filter(void *ads, int data_idx, int *val)
{
return ADS7846_FILTER_OK;
}
static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m)
{
struct spi_transfer *t =
list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
if (ts->model == 7845) {
return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3;
} else {
/*
* adjust: on-wire is a must-ignore bit, a BE12 value, then
* padding; built from two 8 bit values written msb-first.
*/
return be16_to_cpup((__be16 *)t->rx_buf) >> 3;
}
}
static void ads7846_update_value(struct spi_message *m, int val)
{
struct spi_transfer *t =
list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
*(u16 *)t->rx_buf = val;
}
static void ads7846_read_state(struct ads7846 *ts)
{
struct ads7846_packet *packet = ts->packet;
struct spi_message *m;
int msg_idx = 0;
int val;
int action;
int error;
while (msg_idx < ts->msg_count) {
ts->wait_for_sync();
m = &ts->msg[msg_idx];
error = spi_sync(ts->spi, m);
if (error) {
dev_err(&ts->spi->dev, "spi_async --> %d\n", error);
packet->tc.ignore = true;
return;
}
/*
* Last message is power down request, no need to convert
* or filter the value.
*/
if (msg_idx < ts->msg_count - 1) {
val = ads7846_get_value(ts, m);
action = ts->filter(ts->filter_data, msg_idx, &val);
switch (action) {
case ADS7846_FILTER_REPEAT:
continue;
case ADS7846_FILTER_IGNORE:
packet->tc.ignore = true;
msg_idx = ts->msg_count - 1;
continue;
case ADS7846_FILTER_OK:
ads7846_update_value(m, val);
packet->tc.ignore = false;
msg_idx++;
break;
default:
BUG();
}
} else {
msg_idx++;
}
}
}
static void ads7846_report_state(struct ads7846 *ts)
{
struct ads7846_packet *packet = ts->packet;
unsigned int Rt;
u16 x, y, z1, z2;
/*
* ads7846_get_value() does in-place conversion (including byte swap)
* from on-the-wire format as part of debouncing to get stable
* readings.
*/
if (ts->model == 7845) {
x = *(u16 *)packet->tc.x_buf;
y = *(u16 *)packet->tc.y_buf;
z1 = 0;
z2 = 0;
} else {
x = packet->tc.x;
y = packet->tc.y;
z1 = packet->tc.z1;
z2 = packet->tc.z2;
}
/* range filtering */
if (x == MAX_12BIT)
x = 0;
if (ts->model == 7843) {
Rt = ts->pressure_max / 2;
} else if (ts->model == 7845) {
if (get_pendown_state(ts))
Rt = ts->pressure_max / 2;
else
Rt = 0;
dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt);
} else if (likely(x && z1)) {
/* compute touch pressure resistance using equation #2 */
Rt = z2;
Rt -= z1;
Rt *= x;
Rt *= ts->x_plate_ohms;
Rt /= z1;
Rt = (Rt + 2047) >> 12;
} else {
Rt = 0;
}
/*
* Sample found inconsistent by debouncing or pressure is beyond
* the maximum. Don't report it to user space, repeat at least
* once more the measurement
*/
if (packet->tc.ignore || Rt > ts->pressure_max) {
dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
packet->tc.ignore, Rt);
return;
}
/*
* Maybe check the pendown state before reporting. This discards
* false readings when the pen is lifted.
*/
if (ts->penirq_recheck_delay_usecs) {
udelay(ts->penirq_recheck_delay_usecs);
if (!get_pendown_state(ts))
Rt = 0;
}
/*
* NOTE: We can't rely on the pressure to determine the pen down
* state, even this controller has a pressure sensor. The pressure
* value can fluctuate for quite a while after lifting the pen and
* in some cases may not even settle at the expected value.
*
* The only safe way to check for the pen up condition is in the
* timer by reading the pen signal state (it's a GPIO _and_ IRQ).
*/
if (Rt) {
struct input_dev *input = ts->input;
if (ts->swap_xy)
swap(x, y);
if (!ts->pendown) {
input_report_key(input, BTN_TOUCH, 1);
ts->pendown = true;
dev_vdbg(&ts->spi->dev, "DOWN\n");
}
input_report_abs(input, ABS_X, x);
input_report_abs(input, ABS_Y, y);
input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
input_sync(input);
dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
}
}
static irqreturn_t ads7846_hard_irq(int irq, void *handle)
{
struct ads7846 *ts = handle;
return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
}
static irqreturn_t ads7846_irq(int irq, void *handle)
{
struct ads7846 *ts = handle;
/* Start with a small delay before checking pendown state */
msleep(TS_POLL_DELAY);
while (!ts->stopped && get_pendown_state(ts)) {
/* pen is down, continue with the measurement */
ads7846_read_state(ts);
if (!ts->stopped)
ads7846_report_state(ts);
wait_event_timeout(ts->wait, ts->stopped,
msecs_to_jiffies(TS_POLL_PERIOD));
}
if (ts->pendown) {
struct input_dev *input = ts->input;
input_report_key(input, BTN_TOUCH, 0);
input_report_abs(input, ABS_PRESSURE, 0);
input_sync(input);
ts->pendown = false;
dev_vdbg(&ts->spi->dev, "UP\n");
}
return IRQ_HANDLED;
}
static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
mutex_lock(&ts->lock);
if (!ts->suspended) {
if (!ts->disabled)
__ads7846_disable(ts);
if (device_may_wakeup(&ts->spi->dev))
enable_irq_wake(ts->spi->irq);
ts->suspended = true;
}
mutex_unlock(&ts->lock);
return 0;
}
static int ads7846_resume(struct spi_device *spi)
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
mutex_lock(&ts->lock);
if (ts->suspended) {
ts->suspended = false;
if (device_may_wakeup(&ts->spi->dev))
disable_irq_wake(ts->spi->irq);
if (!ts->disabled)
__ads7846_enable(ts);
}
mutex_unlock(&ts->lock);
return 0;
}
static int __devinit ads7846_setup_pendown(struct spi_device *spi, struct ads7846 *ts)
{
struct ads7846_platform_data *pdata = spi->dev.platform_data;
int err;
/* REVISIT when the irq can be triggered active-low, or if for some
* reason the touchscreen isn't hooked up, we don't need to access
* the pendown state.
*/
if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
return -EINVAL;
}
if (pdata->get_pendown_state) {
ts->get_pendown_state = pdata->get_pendown_state;
return 0;
}
err = gpio_request(pdata->gpio_pendown, "ads7846_pendown");
if (err) {
dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
pdata->gpio_pendown);
return err;
}
ts->gpio_pendown = pdata->gpio_pendown;
return 0;
}
/*
* Set up the transfers to read touchscreen state; this assumes we
* use formula #2 for pressure, not #3.
*/
static void __devinit ads7846_setup_spi_msg(struct ads7846 *ts,
const struct ads7846_platform_data *pdata)
{
struct spi_message *m = &ts->msg[0];
struct spi_transfer *x = ts->xfer;
struct ads7846_packet *packet = ts->packet;
int vref = pdata->keep_vref_on;
if (ts->model == 7873) {
/*
* The AD7873 is almost identical to the ADS7846
* keep VREF off during differential/ratiometric
* conversion modes.
*/
ts->model = 7846;
vref = 0;
}
ts->msg_count = 1;
spi_message_init(m);
m->context = ts;
if (ts->model == 7845) {
packet->read_y_cmd[0] = READ_Y(vref);
packet->read_y_cmd[1] = 0;
packet->read_y_cmd[2] = 0;
x->tx_buf = &packet->read_y_cmd[0];
x->rx_buf = &packet->tc.y_buf[0];
x->len = 3;
spi_message_add_tail(x, m);
} else {
/* y- still on; turn on only y+ (and ADC) */
packet->read_y = READ_Y(vref);
x->tx_buf = &packet->read_y;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.y;
x->len = 2;
spi_message_add_tail(x, m);
}
/*
* The first sample after switching drivers can be low quality;
* optionally discard it, using a second one after the signals
* have had enough time to stabilize.
*/
if (pdata->settle_delay_usecs) {
x->delay_usecs = pdata->settle_delay_usecs;
x++;
x->tx_buf = &packet->read_y;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.y;
x->len = 2;
spi_message_add_tail(x, m);
}
ts->msg_count++;
m++;
spi_message_init(m);
m->context = ts;
if (ts->model == 7845) {
x++;
packet->read_x_cmd[0] = READ_X(vref);
packet->read_x_cmd[1] = 0;
packet->read_x_cmd[2] = 0;
x->tx_buf = &packet->read_x_cmd[0];
x->rx_buf = &packet->tc.x_buf[0];
x->len = 3;
spi_message_add_tail(x, m);
} else {
/* turn y- off, x+ on, then leave in lowpower */
x++;
packet->read_x = READ_X(vref);
x->tx_buf = &packet->read_x;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.x;
x->len = 2;
spi_message_add_tail(x, m);
}
/* ... maybe discard first sample ... */
if (pdata->settle_delay_usecs) {
x->delay_usecs = pdata->settle_delay_usecs;
x++;
x->tx_buf = &packet->read_x;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.x;
x->len = 2;
spi_message_add_tail(x, m);
}
/* turn y+ off, x- on; we'll use formula #2 */
if (ts->model == 7846) {
ts->msg_count++;
m++;
spi_message_init(m);
m->context = ts;
x++;
packet->read_z1 = READ_Z1(vref);
x->tx_buf = &packet->read_z1;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.z1;
x->len = 2;
spi_message_add_tail(x, m);
/* ... maybe discard first sample ... */
if (pdata->settle_delay_usecs) {
x->delay_usecs = pdata->settle_delay_usecs;
x++;
x->tx_buf = &packet->read_z1;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.z1;
x->len = 2;
spi_message_add_tail(x, m);
}
ts->msg_count++;
m++;
spi_message_init(m);
m->context = ts;
x++;
packet->read_z2 = READ_Z2(vref);
x->tx_buf = &packet->read_z2;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.z2;
x->len = 2;
spi_message_add_tail(x, m);
/* ... maybe discard first sample ... */
if (pdata->settle_delay_usecs) {
x->delay_usecs = pdata->settle_delay_usecs;
x++;
x->tx_buf = &packet->read_z2;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->tc.z2;
x->len = 2;
spi_message_add_tail(x, m);
}
}
/* power down */
ts->msg_count++;
m++;
spi_message_init(m);
m->context = ts;
if (ts->model == 7845) {
x++;
packet->pwrdown_cmd[0] = PWRDOWN;
packet->pwrdown_cmd[1] = 0;
packet->pwrdown_cmd[2] = 0;
x->tx_buf = &packet->pwrdown_cmd[0];
x->len = 3;
} else {
x++;
packet->pwrdown = PWRDOWN;
x->tx_buf = &packet->pwrdown;
x->len = 1;
spi_message_add_tail(x, m);
x++;
x->rx_buf = &packet->dummy;
x->len = 2;
}
CS_CHANGE(*x);
spi_message_add_tail(x, m);
}
static int __devinit ads7846_probe(struct spi_device *spi)
{
struct ads7846 *ts;
struct ads7846_packet *packet;
struct input_dev *input_dev;
struct ads7846_platform_data *pdata = spi->dev.platform_data;
unsigned long irq_flags;
int err;
if (!spi->irq) {
dev_dbg(&spi->dev, "no IRQ?\n");
return -ENODEV;
}
if (!pdata) {
dev_dbg(&spi->dev, "no platform data?\n");
return -ENODEV;
}
/* don't exceed max specified sample rate */
if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
(spi->max_speed_hz/SAMPLE_BITS)/1000);
return -EINVAL;
}
/* We'd set TX word size 8 bits and RX word size to 13 bits ... except
* that even if the hardware can do that, the SPI controller driver
* may not. So we stick to very-portable 8 bit words, both RX and TX.
*/
spi->bits_per_word = 8;
spi->mode = SPI_MODE_0;
err = spi_setup(spi);
if (err < 0)
return err;
ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
input_dev = input_allocate_device();
if (!ts || !packet || !input_dev) {
err = -ENOMEM;
goto err_free_mem;
}
dev_set_drvdata(&spi->dev, ts);
ts->packet = packet;
ts->spi = spi;
ts->input = input_dev;
ts->vref_mv = pdata->vref_mv;
ts->swap_xy = pdata->swap_xy;
mutex_init(&ts->lock);
init_waitqueue_head(&ts->wait);
ts->model = pdata->model ? : 7846;
ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
ts->pressure_max = pdata->pressure_max ? : ~0;
if (pdata->filter != NULL) {
if (pdata->filter_init != NULL) {
err = pdata->filter_init(pdata, &ts->filter_data);
if (err < 0)
goto err_free_mem;
}
ts->filter = pdata->filter;
ts->filter_cleanup = pdata->filter_cleanup;
} else if (pdata->debounce_max) {
ts->debounce_max = pdata->debounce_max;
if (ts->debounce_max < 2)
ts->debounce_max = 2;
ts->debounce_tol = pdata->debounce_tol;
ts->debounce_rep = pdata->debounce_rep;
ts->filter = ads7846_debounce_filter;
ts->filter_data = ts;
} else {
ts->filter = ads7846_no_filter;
}
err = ads7846_setup_pendown(spi, ts);
if (err)
goto err_cleanup_filter;
if (pdata->penirq_recheck_delay_usecs)
ts->penirq_recheck_delay_usecs =
pdata->penirq_recheck_delay_usecs;
ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
input_dev->name = ts->name;
input_dev->phys = ts->phys;
input_dev->dev.parent = &spi->dev;
input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
input_set_abs_params(input_dev, ABS_X,
pdata->x_min ? : 0,
pdata->x_max ? : MAX_12BIT,
0, 0);
input_set_abs_params(input_dev, ABS_Y,
pdata->y_min ? : 0,
pdata->y_max ? : MAX_12BIT,
0, 0);
input_set_abs_params(input_dev, ABS_PRESSURE,
pdata->pressure_min, pdata->pressure_max, 0, 0);
ads7846_setup_spi_msg(ts, pdata);
ts->reg = regulator_get(&spi->dev, "vcc");
if (IS_ERR(ts->reg)) {
err = PTR_ERR(ts->reg);
dev_err(&spi->dev, "unable to get regulator: %d\n", err);
goto err_free_gpio;
}
err = regulator_enable(ts->reg);
if (err) {
dev_err(&spi->dev, "unable to enable regulator: %d\n", err);
goto err_put_regulator;
}
irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
irq_flags |= IRQF_ONESHOT;
err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq,
irq_flags, spi->dev.driver->name, ts);
if (err && !pdata->irq_flags) {
dev_info(&spi->dev,
"trying pin change workaround on irq %d\n", spi->irq);
irq_flags |= IRQF_TRIGGER_RISING;
err = request_threaded_irq(spi->irq,
ads7846_hard_irq, ads7846_irq,
irq_flags, spi->dev.driver->name, ts);
}
if (err) {
dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
goto err_disable_regulator;
}
err = ads784x_hwmon_register(spi, ts);
if (err)
goto err_free_irq;
dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
/*
* Take a first sample, leaving nPENIRQ active and vREF off; avoid
* the touchscreen, in case it's not connected.
*/
if (ts->model == 7845)
ads7845_read12_ser(&spi->dev, PWRDOWN);
else
(void) ads7846_read12_ser(&spi->dev,
READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
if (err)
goto err_remove_hwmon;
err = input_register_device(input_dev);
if (err)
goto err_remove_attr_group;
device_init_wakeup(&spi->dev, pdata->wakeup);
return 0;
err_remove_attr_group:
sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
err_remove_hwmon:
ads784x_hwmon_unregister(spi, ts);
err_free_irq:
free_irq(spi->irq, ts);
err_disable_regulator:
regulator_disable(ts->reg);
err_put_regulator:
regulator_put(ts->reg);
err_free_gpio:
if (ts->gpio_pendown != -1)
gpio_free(ts->gpio_pendown);
err_cleanup_filter:
if (ts->filter_cleanup)
ts->filter_cleanup(ts->filter_data);
err_free_mem:
input_free_device(input_dev);
kfree(packet);
kfree(ts);
return err;
}
static int __devexit ads7846_remove(struct spi_device *spi)
{
struct ads7846 *ts = dev_get_drvdata(&spi->dev);
device_init_wakeup(&spi->dev, false);
sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
ads7846_disable(ts);
free_irq(ts->spi->irq, ts);
input_unregister_device(ts->input);
ads784x_hwmon_unregister(spi, ts);
regulator_disable(ts->reg);
regulator_put(ts->reg);
if (ts->gpio_pendown != -1)
gpio_free(ts->gpio_pendown);
if (ts->filter_cleanup)
ts->filter_cleanup(ts->filter_data);
kfree(ts->packet);
kfree(ts);
dev_dbg(&spi->dev, "unregistered touchscreen\n");
return 0;
}
static struct spi_driver ads7846_driver = {
.driver = {
.name = "ads7846",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = ads7846_probe,
.remove = __devexit_p(ads7846_remove),
.suspend = ads7846_suspend,
.resume = ads7846_resume,
};
static int __init ads7846_init(void)
{
return spi_register_driver(&ads7846_driver);
}
module_init(ads7846_init);
static void __exit ads7846_exit(void)
{
spi_unregister_driver(&ads7846_driver);
}
module_exit(ads7846_exit);
MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:ads7846");