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iio: adc: ad7380: add alert support

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The alert functionality is an out of range indicator and can be used as
an early indicator of an out of bounds conversion result.

ALERT_LOW_THRESHOLD and ALERT_HIGH_THRESHOLD registers are common to all
channels.

When using 1 SDO line (only mode supported by the driver right now), i.e
data outputs only on SDOA, SDOB (or SDOD for 4 channels variants) is
used as an alert pin. The alert pin is updated at the end of the
conversion (set to low if an alert occurs) and is cleared on a falling
edge of CS.

The ALERT register contains information about the exact alert status:
channel and direction. ALERT register can be accessed using debugfs if
enabled.

User can set high/low thresholds and enable alert detection using the
regular iio events attributes:

  events/in_thresh_falling_value events/in_thresh_rising_value
  events/thresh_either_en

In most use cases, user will hardwire the alert pin to trigger a shutdown.

In theory, we could generate userspace IIO events for alerts, but this
is not implemented yet for several reasons [1]. This can be implemented
later if a real use case actually requires it.

Signed-off-by: Julien Stephan <jstephan@baylibre.com>

[1] https://lore.kernel.org/all/4be16272-5197-4fa1-918c-c4cdfcaee02e@baylibre.com/

Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250108-ad7380-add-alert-support-v4-4-1751802471ba@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Julien Stephan 2025-01-08 13:49:36 +01:00 committed by Jonathan Cameron
parent adc59fe0c2
commit 27d1a4dbe1
1 changed files with 192 additions and 0 deletions
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192
drivers/iio/adc/ad7380.c
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@ -34,6 +34,7 @@
#include <linux/util_macros.h>
#include <linux/iio/buffer.h>
#include <linux/iio/events.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
@ -112,6 +113,24 @@ struct ad7380_chip_info {
const struct ad7380_timing_specs *timing_specs;
};
static const struct iio_event_spec ad7380_events[] = {
{
.type = IIO_EV_TYPE_THRESH,
.dir = IIO_EV_DIR_RISING,
.mask_shared_by_dir = BIT(IIO_EV_INFO_VALUE),
},
{
.type = IIO_EV_TYPE_THRESH,
.dir = IIO_EV_DIR_FALLING,
.mask_shared_by_dir = BIT(IIO_EV_INFO_VALUE),
},
{
.type = IIO_EV_TYPE_THRESH,
.dir = IIO_EV_DIR_EITHER,
.mask_shared_by_all = BIT(IIO_EV_INFO_ENABLE),
},
};
enum {
AD7380_SCAN_TYPE_NORMAL,
AD7380_SCAN_TYPE_RESOLUTION_BOOST,
@ -214,6 +233,8 @@ static const struct iio_scan_type ad7380_scan_type_16_u[] = {
.has_ext_scan_type = 1, \
.ext_scan_type = ad7380_scan_type_##bits##_##sign, \
.num_ext_scan_type = ARRAY_SIZE(ad7380_scan_type_##bits##_##sign), \
.event_spec = ad7380_events, \
.num_event_specs = ARRAY_SIZE(ad7380_events), \
}
#define AD7380_CHANNEL(index, bits, diff, sign) \
@ -1157,12 +1178,183 @@ static int ad7380_get_current_scan_type(const struct iio_dev *indio_dev,
: AD7380_SCAN_TYPE_NORMAL;
}
static int ad7380_read_event_config(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
enum iio_event_type type,
enum iio_event_direction dir)
{
struct ad7380_state *st = iio_priv(indio_dev);
int tmp, ret;
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
ret = regmap_read(st->regmap, AD7380_REG_ADDR_CONFIG1, &tmp);
iio_device_release_direct_mode(indio_dev);
if (ret)
return ret;
return FIELD_GET(AD7380_CONFIG1_ALERTEN, tmp);
}
static int ad7380_write_event_config(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
enum iio_event_type type,
enum iio_event_direction dir,
bool state)
{
struct ad7380_state *st = iio_priv(indio_dev);
int ret;
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
ret = regmap_update_bits(st->regmap,
AD7380_REG_ADDR_CONFIG1,
AD7380_CONFIG1_ALERTEN,
FIELD_PREP(AD7380_CONFIG1_ALERTEN, state));
iio_device_release_direct_mode(indio_dev);
return ret;
}
static int ad7380_get_alert_th(struct ad7380_state *st,
enum iio_event_direction dir,
int *val)
{
int ret, tmp;
switch (dir) {
case IIO_EV_DIR_RISING:
ret = regmap_read(st->regmap,
AD7380_REG_ADDR_ALERT_HIGH_TH,
&tmp);
if (ret)
return ret;
*val = FIELD_GET(AD7380_ALERT_HIGH_TH, tmp);
return IIO_VAL_INT;
case IIO_EV_DIR_FALLING:
ret = regmap_read(st->regmap,
AD7380_REG_ADDR_ALERT_LOW_TH,
&tmp);
if (ret)
return ret;
*val = FIELD_GET(AD7380_ALERT_LOW_TH, tmp);
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static int ad7380_read_event_value(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
enum iio_event_type type,
enum iio_event_direction dir,
enum iio_event_info info,
int *val, int *val2)
{
struct ad7380_state *st = iio_priv(indio_dev);
int ret;
switch (info) {
case IIO_EV_INFO_VALUE:
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
ret = ad7380_get_alert_th(st, dir, val);
iio_device_release_direct_mode(indio_dev);
return ret;
default:
return -EINVAL;
}
}
static int ad7380_set_alert_th(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
enum iio_event_direction dir,
int val)
{
struct ad7380_state *st = iio_priv(indio_dev);
const struct iio_scan_type *scan_type;
u16 th;
/*
* According to the datasheet,
* AD7380_REG_ADDR_ALERT_HIGH_TH[11:0] are the 12 MSB of the
* 16-bits internal alert high register. LSB are set to 0xf.
* AD7380_REG_ADDR_ALERT_LOW_TH[11:0] are the 12 MSB of the
* 16 bits internal alert low register. LSB are set to 0x0.
*
* When alert is enabled the conversion from the adc is compared
* immediately to the alert high/low thresholds, before any
* oversampling. This means that the thresholds are the same for
* normal mode and oversampling mode.
*/
/* Extract the 12 MSB of val */
scan_type = iio_get_current_scan_type(indio_dev, chan);
if (IS_ERR(scan_type))
return PTR_ERR(scan_type);
th = val >> (scan_type->realbits - 12);
switch (dir) {
case IIO_EV_DIR_RISING:
return regmap_write(st->regmap,
AD7380_REG_ADDR_ALERT_HIGH_TH,
th);
case IIO_EV_DIR_FALLING:
return regmap_write(st->regmap,
AD7380_REG_ADDR_ALERT_LOW_TH,
th);
default:
return -EINVAL;
}
}
static int ad7380_write_event_value(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
enum iio_event_type type,
enum iio_event_direction dir,
enum iio_event_info info,
int val, int val2)
{
int ret;
switch (info) {
case IIO_EV_INFO_VALUE:
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
ret = ad7380_set_alert_th(indio_dev, chan, dir, val);
iio_device_release_direct_mode(indio_dev);
return ret;
default:
return -EINVAL;
}
}
static const struct iio_info ad7380_info = {
.read_raw = &ad7380_read_raw,
.read_avail = &ad7380_read_avail,
.write_raw = &ad7380_write_raw,
.get_current_scan_type = &ad7380_get_current_scan_type,
.debugfs_reg_access = &ad7380_debugfs_reg_access,
.read_event_config = &ad7380_read_event_config,
.write_event_config = &ad7380_write_event_config,
.read_event_value = &ad7380_read_event_value,
.write_event_value = &ad7380_write_event_value,
};
static int ad7380_init(struct ad7380_state *st, bool external_ref_en)