iio: adc: ad7380: add alert support

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>

diff --git a/drivers/iio/adc/ad7380.c b/drivers/iio/adc/ad7380.c
index a532de4422082df8503454d66fc49f75b52cff68..a18dcd664c1b5e5032cc55c063e5681d11c23352 100644 (file)
--- a/drivers/iio/adc/ad7380.c
+++ b/drivers/iio/adc/ad7380.c
@@ -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)