// SPDX-License-Identifier: GPL-2.0-only
/*
* ADS7846 based touchscreen and sensor driver
*
* Copyright (c) 2005 David Brownell
* Copyright (c) 2006 Nokia Corporation
* Various changes: Imre Deak <[email protected]>
*
* 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
*/
#include <linux/types.h>
#include <linux/hwmon.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/input/touchscreen.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/pm.h>
#include <linux/property.h>
#include <linux/gpio/consumer.h>
#include <linux/spi/spi.h>
#include <linux/spi/ads7846.h>
#include <linux/regulator/consumer.h>
#include <linux/module.h>
#include <linux/unaligned.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 ads7846_buf {
u8 cmd;
__be16 data;
} __packed;
struct ads7846_buf_layout {
unsigned int offset;
unsigned int count;
unsigned int skip;
};
/*
* 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 {
unsigned int count;
unsigned int count_skip;
unsigned int cmds;
unsigned int last_cmd_idx;
struct ads7846_buf_layout l[5];
struct ads7846_buf *rx;
struct ads7846_buf *tx;
struct ads7846_buf pwrdown_cmd;
bool ignore;
u16 x, y, z1, z2;
};
struct ads7846 {
struct input_dev *input;
char phys[32];
char name[32];
struct spi_device *spi;
struct regulator *reg;
u16 model;
u16 vref_mv;
u16 vref_delay_usecs;
u16 x_plate_ohms;
u16 pressure_max;
bool swap_xy;
bool use_internal;
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 touchscreen_properties core_prop;
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;
int (*get_pendown_state)(void);
struct gpio_desc *gpio_pendown;
struct gpio_desc *gpio_hsync;
void (*wait_for_sync)(void);
};
enum ads7846_filter {
ADS7846_FILTER_OK,
ADS7846_FILTER_REPEAT,
ADS7846_FILTER_IGNORE,
};
/* 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))
/* Order commands in the most optimal way to reduce Vref switching and
* settling time:
* Measure: X; Vref: X+, X-; IN: Y+
* Measure: Y; Vref: Y+, Y-; IN: X+
* Measure: Z1; Vref: Y+, X-; IN: X+
* Measure: Z2; Vref: Y+, X-; IN: Y-
*/
enum ads7846_cmds {
ADS7846_X,
ADS7846_Y,
ADS7846_Z1,
ADS7846_Z2,
ADS7846_PWDOWN,
};
static int get_pendown_state(struct ads7846 *ts)
{
if (ts->get_pendown_state)
return ts->get_pendown_state();
return gpiod_get_value(ts->gpio_pendown);
}
static void ads7846_report_pen_up(struct ads7846 *ts)
{
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");
}
/* 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) {
/* Check if pen was released since last stop */
if (ts->pendown && !get_pendown_state(ts))
ads7846_report_pen_up(ts);
/* 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)
{
int error;
error = regulator_enable(ts->reg);
if (error != 0)
dev_err(&ts->spi->dev, "Failed to enable supply: %d\n", error);
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;
struct spi_message msg;
struct spi_transfer xfer[6];
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
*/
__be16 sample ____cacheline_aligned;
};
struct ads7845_ser_req {
u8 command[3];
struct spi_message msg;
struct spi_transfer xfer[2];
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
*/
u8 sample[3] ____cacheline_aligned;
};
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;
req = kzalloc(sizeof *req, GFP_KERNEL);
if (!req)
return -ENOMEM;
spi_message_init(&req->msg);
/* maybe turn on internal vREF, and let it settle */
if (ts->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.value = ts->vref_delay_usecs;
req->xfer[1].delay.unit = SPI_DELAY_UNIT_USECS;
spi_message_add_tail(&req->xfer[1], &req->msg);
/* Enable reference voltage */
command |= ADS_PD10_REF_ON;
}
/* Enable ADC in every case */
command |= ADS_PD10_ADC_ON;
/* 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 = get_unaligned_be16(&req->sample[1]);
status = status >> 3;
status &= 0x0fff;
}
kfree(req);
return status;
}
#if IS_ENABLED(CONFIG_HWMON)
#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(&ts->spi->dev, \
READ_12BIT_SER(var)); \
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 umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr,
int index)
{
struct device *dev = kobj_to_dev(kobj);
struct ads7846 *ts = dev_get_drvdata(dev);
if (ts->model == 7843 && index < 2) /* in0, in1 */
return 0;
if (ts->model == 7845 && index != 2) /* in0 */
return 0;
return attr->mode;
}
static struct attribute *ads7846_attributes[] = {
&dev_attr_temp0.attr, /* 0 */
&dev_attr_temp1.attr, /* 1 */
&dev_attr_in0_input.attr, /* 2 */
&dev_attr_in1_input.attr, /* 3 */
NULL,
};
static const struct attribute_group ads7846_attr_group = {
.attrs = ads7846_attributes,
.is_visible = ads7846_is_visible,
};
__ATTRIBUTE_GROUPS(ads7846_attr);
static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
{
struct device *hwmon;
/* 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;
ts->use_internal = true;
}
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;
}
hwmon = devm_hwmon_device_register_with_groups(&spi->dev,
spi->modalias, ts,
ads7846_attr_groups);
return PTR_ERR_OR_ZERO(hwmon);
}
#else
static inline int ads784x_hwmon_register(struct spi_device *spi,
struct ads7846 *ts)
{
return 0;
}
#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 int i;
int err;
err = kstrtouint(buf, 10, &i);
if (err)
return err;
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_attrs[] = {
&dev_attr_pen_down.attr,
&dev_attr_disable.attr,
NULL,
};
ATTRIBUTE_GROUPS(ads784x);
/*--------------------------------------------------------------------------*/
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_buf *buf)
{
int value;
value = be16_to_cpup(&buf->data);
/* enforce ADC output is 12 bits width */
return (value >> 3) & 0xfff;
}
static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx,
u16 val)
{
struct ads7846_packet *packet = ts->packet;
switch (cmd_idx) {
case ADS7846_Y:
packet->y = val;
break;
case ADS7846_X:
packet->x = val;
break;
case ADS7846_Z1:
packet->z1 = val;
break;
case ADS7846_Z2:
packet->z2 = val;
break;
default:
WARN_ON_ONCE(1);
}
}
static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref)
{
switch (cmd_idx) {
case ADS7846_Y:
return READ_Y(vref);
case ADS7846_X:
return READ_X(vref);
/* 7846 specific commands */
case ADS7846_Z1:
return READ_Z1(vref);
case ADS7846_Z2:
return READ_Z2(vref);
case ADS7846_PWDOWN:
return PWRDOWN;
default:
WARN_ON_ONCE(1);
}
return 0;
}
static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx)
{
switch (cmd_idx) {
case ADS7846_X:
case ADS7846_Y:
case ADS7846_Z1:
case ADS7846_Z2:
return true;
case ADS7846_PWDOWN:
return false;
default:
WARN_ON_ONCE(1);
}
return false;
}
static int ads7846_filter(struct ads7846 *ts)
{
struct ads7846_packet *packet = ts->packet;
int action;
int val;
unsigned int cmd_idx, b;
packet->ignore = false;
for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) {
struct ads7846_buf_layout *l = &packet->l[cmd_idx];
packet->last_cmd_idx = cmd_idx;
for (b = l->skip; b < l->count; b++) {
val = ads7846_get_value(&packet->rx[l->offset + b]);
action = ts->filter(ts->filter_data, cmd_idx, &val);
if (action == ADS7846_FILTER_REPEAT) {
if (b == l->count - 1)
return -EAGAIN;
} else if (action == ADS7846_FILTER_OK) {
ads7846_set_cmd_val(ts, cmd_idx, val);
break;
} else {
packet->ignore = true;
return 0;
}
}
}
return 0;
}
static void ads7846_wait_for_hsync(struct ads7846 *ts)
{
if (ts->wait_for_sync) {
ts->wait_for_sync();
return;
}
if (!ts->gpio_hsync)
return;
/*
* Wait for HSYNC to assert the line should be flagged
* as active low so here we are waiting for it to assert
*/
while (!gpiod_get_value(ts->gpio_hsync))
cpu_relax();
/* Then we wait for it do de-assert */
while (gpiod_get_value(ts->gpio_hsync))
cpu_relax();
}
static void ads7846_read_state(struct ads7846 *ts)
{
struct ads7846_packet *packet = ts->packet;
struct spi_message *m;
int msg_idx = 0;
int error;
packet->last_cmd_idx = 0;
while (true) {
ads7846_wait_for_hsync(ts);
m = &ts->msg[msg_idx];
error = spi_sync(ts->spi, m);
if (error) {
dev_err_ratelimited(&ts->spi->dev, "spi_sync --> %d\n", error);
packet->ignore = true;
return;
}
error = ads7846_filter(ts);
if (error)
continue;
return;
}
}
static void ads7846_report_state(struct ads7846 *ts)
{
struct ads7846_packet *packet = ts->packet;
unsigned int Rt;
u16 x, y, z1, z2;
x = packet->x;
y = packet->y;
if (ts->model == 7845) {
z1 = 0;
z2 = 0;
} else {
z1 = packet->z1;
z2 = packet->z2;
}
/* range filtering */
if (x == MAX_12BIT)
x = 0;
if (ts->model == 7843 || ts->model == 7845) {
Rt = ts->pressure_max / 2;
} else if (likely(x && z1)) {
/* compute touch pressure resistance using equation #2 */
Rt = z2;
Rt -= z1;
Rt *= ts->x_plate_ohms;
Rt = DIV_ROUND_CLOSEST(Rt, 16);
Rt *= x;
Rt /= z1;
Rt = DIV_ROUND_CLOSEST(Rt, 256);
} 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->ignore || Rt > ts->pressure_max) {
dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
packet->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->pendown) {
input_report_key(input, BTN_TOUCH, 1);
ts->pendown = true;
dev_vdbg(&ts->spi->dev, "DOWN\n");
}
touchscreen_report_pos(input, &ts->core_prop, x, y, false);
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 && !ts->stopped)
ads7846_report_pen_up(ts);
return IRQ_HANDLED;
}
static int ads7846_suspend(struct device *dev)
{
struct ads7846 *ts = dev_get_drvdata(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 device *dev)
{
struct ads7846 *ts = dev_get_drvdata(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 DEFINE_SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
static int ads7846_setup_pendown(struct spi_device *spi,
struct ads7846 *ts,
const struct ads7846_platform_data *pdata)
{
/*
* 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) {
ts->get_pendown_state = pdata->get_pendown_state;
} else {
ts->gpio_pendown = gpiod_get(&spi->dev, "pendown", GPIOD_IN);
if (IS_ERR(ts->gpio_pendown)) {
dev_err(&spi->dev, "failed to request pendown GPIO\n");
return PTR_ERR(ts->gpio_pendown);
}
if (pdata->gpio_pendown_debounce)
gpiod_set_debounce(ts->gpio_pendown,
pdata->gpio_pendown_debounce);
}
return 0;
}
/*
* Set up the transfers to read touchscreen state; this assumes we
* use formula #2 for pressure, not #3.
*/
static int 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;
unsigned int count, offset = 0;
unsigned int cmd_idx, b;
unsigned long time;
size_t size = 0;
/* time per bit */
time = NSEC_PER_SEC / ts->spi->max_speed_hz;
count = pdata->settle_delay_usecs * NSEC_PER_USEC / time;
packet->count_skip = DIV_ROUND_UP(count, 24);
if (ts->debounce_max && ts->debounce_rep)
/* ads7846_debounce_filter() is making ts->debounce_rep + 2
* reads. So we need to get all samples for normal case. */
packet->count = ts->debounce_rep + 2;
else
packet->count = 1;
if (ts->model == 7846)
packet->cmds = 5; /* x, y, z1, z2, pwdown */
else
packet->cmds = 3; /* x, y, pwdown */
for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
struct ads7846_buf_layout *l = &packet->l[cmd_idx];
unsigned int max_count;
if (cmd_idx == packet->cmds - 1)
cmd_idx = ADS7846_PWDOWN;
if (ads7846_cmd_need_settle(cmd_idx))
max_count = packet->count + packet->count_skip;
else
max_count = packet->count;
l->offset = offset;
offset += max_count;
l->count = max_count;
l->skip = packet->count_skip;
size += sizeof(*packet->tx) * max_count;
}
packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
if (!packet->tx)
return -ENOMEM;
packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
if (!packet->rx)
return -ENOMEM;
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;
for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
struct ads7846_buf_layout *l = &packet->l[cmd_idx];
u8 cmd;
if (cmd_idx == packet->cmds - 1)
cmd_idx = ADS7846_PWDOWN;
cmd = ads7846_get_cmd(cmd_idx, vref);
for (b = 0; b < l->count; b++)
packet->tx[l->offset + b].cmd = cmd;
}
x->tx_buf = packet->tx;
x->rx_buf = packet->rx;
x->len = size;
spi_message_add_tail(x, m);
return 0;
}
static const struct of_device_id ads7846_dt_ids[] = {
{ .compatible = "ti,tsc2046", .data = (void *) 7846 },
{ .compatible = "ti,ads7843", .data = (void *) 7843 },
{ .compatible = "ti,ads7845", .data = (void *) 7845 },
{ .compatible = "ti,ads7846", .data = (void *) 7846 },
{ .compatible = "ti,ads7873", .data = (void *) 7873 },
{ }
};
MODULE_DEVICE_TABLE(of, ads7846_dt_ids);
static const struct spi_device_id ads7846_spi_ids[] = {
{ "tsc2046", 7846 },
{ "ads7843", 7843 },
{ "ads7845", 7845 },
{ "ads7846", 7846 },
{ "ads7873", 7873 },
{ },
};
MODULE_DEVICE_TABLE(spi, ads7846_spi_ids);
static const struct ads7846_platform_data *ads7846_get_props(struct device *dev)
{
struct ads7846_platform_data *pdata;
u32 value;
pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return ERR_PTR(-ENOMEM);
pdata->model = (uintptr_t)device_get_match_data(dev);
device_property_read_u16(dev, "ti,vref-delay-usecs",
&pdata->vref_delay_usecs);
device_property_read_u16(dev, "ti,vref-mv", &pdata->vref_mv);
pdata->keep_vref_on = device_property_read_bool(dev, "ti,keep-vref-on");
pdata->swap_xy = device_property_read_bool(dev, "ti,swap-xy");
device_property_read_u16(dev, "ti,settle-delay-usec",
&pdata->settle_delay_usecs);
device_property_read_u16(dev, "ti,penirq-recheck-delay-usecs",
&pdata->penirq_recheck_delay_usecs);
device_property_read_u16(dev, "ti,x-plate-ohms", &pdata->x_plate_ohms);
device_property_read_u16(dev, "ti,y-plate-ohms", &pdata->y_plate_ohms);
device_property_read_u16(dev, "ti,x-min", &pdata->x_min);
device_property_read_u16(dev, "ti,y-min", &pdata->y_min);
device_property_read_u16(dev, "ti,x-max", &pdata->x_max);
device_property_read_u16(dev, "ti,y-max", &pdata->y_max);
/*
* touchscreen-max-pressure gets parsed during
* touchscreen_parse_properties()
*/
device_property_read_u16(dev, "ti,pressure-min", &pdata->pressure_min);
if (!device_property_read_u32(dev, "touchscreen-min-pressure", &value))
pdata->pressure_min = (u16) value;
device_property_read_u16(dev, "ti,pressure-max", &pdata->pressure_max);
device_property_read_u16(dev, "ti,debounce-max", &pdata->debounce_max);
if (!device_property_read_u32(dev, "touchscreen-average-samples", &value))
pdata->debounce_max = (u16) value;
device_property_read_u16(dev, "ti,debounce-tol", &pdata->debounce_tol);
device_property_read_u16(dev, "ti,debounce-rep", &pdata->debounce_rep);
device_property_read_u32(dev, "ti,pendown-gpio-debounce",
&pdata->gpio_pendown_debounce);
pdata->wakeup = device_property_read_bool(dev, "wakeup-source") ||
device_property_read_bool(dev, "linux,wakeup");
return pdata;
}
static void ads7846_regulator_disable(void *regulator)
{
regulator_disable(regulator);
}
static int ads7846_probe(struct spi_device *spi)
{
const struct ads7846_platform_data *pdata;
struct ads7846 *ts;
struct device *dev = &spi->dev;
struct ads7846_packet *packet;
struct input_dev *input_dev;
unsigned long irq_flags;
int err;
if (!spi->irq) {
dev_dbg(dev, "no IRQ?\n");
return -EINVAL;
}
/* don't exceed max specified sample rate */
if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
dev_err(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_X_MASK;
spi->mode |= SPI_MODE_0;
err = spi_setup(spi);
if (err < 0)
return err;
ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL);
if (!ts)
return -ENOMEM;
packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL);
if (!packet)
return -ENOMEM;
input_dev = devm_input_allocate_device(dev);
if (!input_dev)
return -ENOMEM;
spi_set_drvdata(spi, ts);
ts->packet = packet;
ts->spi = spi;
ts->input = input_dev;
mutex_init(&ts->lock);
init_waitqueue_head(&ts->wait);
pdata = dev_get_platdata(dev);
if (!pdata) {
pdata = ads7846_get_props(dev);
if (IS_ERR(pdata))
return PTR_ERR(pdata);
}
ts->model = pdata->model ? : 7846;
ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
ts->vref_mv = pdata->vref_mv;
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, pdata);
if (err)
return err;
if (pdata->penirq_recheck_delay_usecs)
ts->penirq_recheck_delay_usecs =
pdata->penirq_recheck_delay_usecs;
ts->wait_for_sync = pdata->wait_for_sync;
ts->gpio_hsync = devm_gpiod_get_optional(dev, "ti,hsync", GPIOD_IN);
if (IS_ERR(ts->gpio_hsync))
return PTR_ERR(ts->gpio_hsync);
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
input_dev->name = ts->name;
input_dev->phys = ts->phys;
input_dev->id.bustype = BUS_SPI;
input_dev->id.product = pdata->model;
input_set_capability(input_dev, EV_KEY, 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);
if (ts->model != 7845)
input_set_abs_params(input_dev, ABS_PRESSURE,
pdata->pressure_min, pdata->pressure_max, 0, 0);
/*
* Parse common framework properties. Must be done here to ensure the
* correct behaviour in case of using the legacy vendor bindings. The
* general binding value overrides the vendor specific one.
*/
touchscreen_parse_properties(ts->input, false, &ts->core_prop);
ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0;
/*
* Check if legacy ti,swap-xy binding is used instead of
* touchscreen-swapped-x-y
*/
if (!ts->core_prop.swap_x_y && pdata->swap_xy) {
swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]);
ts->core_prop.swap_x_y = true;
}
ads7846_setup_spi_msg(ts, pdata);
ts->reg = devm_regulator_get(dev, "vcc");
if (IS_ERR(ts->reg)) {
err = PTR_ERR(ts->reg);
dev_err(dev, "unable to get regulator: %d\n", err);
return err;
}
err = regulator_enable(ts->reg);
if (err) {
dev_err(dev, "unable to enable regulator: %d\n", err);
return err;
}
err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg);
if (err)
return err;
irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
irq_flags |= IRQF_ONESHOT;
err = devm_request_threaded_irq(dev, spi->irq,
ads7846_hard_irq, ads7846_irq,
irq_flags, dev->driver->name, ts);
if (err && err != -EPROBE_DEFER && !pdata->irq_flags) {
dev_info(dev,
"trying pin change workaround on irq %d\n", spi->irq);
irq_flags |= IRQF_TRIGGER_RISING;
err = devm_request_threaded_irq(dev, spi->irq,
ads7846_hard_irq, ads7846_irq,
irq_flags, dev->driver->name,
ts);
}
if (err) {
dev_dbg(dev, "irq %d busy?\n", spi->irq);
return err;
}
err = ads784x_hwmon_register(spi, ts);
if (err)
return err;
dev_info(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(dev, PWRDOWN);
else
(void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux));
err = input_register_device(input_dev);
if (err)
return err;
device_init_wakeup(dev, pdata->wakeup);
/*
* If device does not carry platform data we must have allocated it
* when parsing DT data.
*/
if (!dev_get_platdata(dev))
devm_kfree(dev, (void *)pdata);
return 0;
}
static void ads7846_remove(struct spi_device *spi)
{
struct ads7846 *ts = spi_get_drvdata(spi);
ads7846_stop(ts);
}
static struct spi_driver ads7846_driver = {
.driver = {
.name = "ads7846",
.dev_groups = ads784x_groups,
.pm = pm_sleep_ptr(&ads7846_pm),
.of_match_table = ads7846_dt_ids,
},
.probe = ads7846_probe,
.remove = ads7846_remove,
.id_table = ads7846_spi_ids,
};
module_spi_driver(ads7846_driver);
MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
MODULE_LICENSE("GPL");
Codebase Browser
linux