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Message-Id: <20250109-ad4111_openwire-v2-2-0372c2dde0ce@baylibre.com>
Date: Thu, 09 Jan 2025 14:55:18 +0100
From: Guillaume Ranquet <granquet@...libre.com>
To: Lars-Peter Clausen <lars@...afoo.de>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Jonathan Cameron <jic23@...nel.org>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
Guillaume Ranquet <granquet@...libre.com>
Subject: [PATCH RFC v2 2/2] iio: adc: ad7173: add openwire detection
support for single conversions
Some chips of the ad7173 family supports open wire detection.
Generate a threshold event whenever an external source is disconnected
from the system input on single conversions.
Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
---
drivers/iio/adc/ad7173.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 164 insertions(+)
diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
index 11ff148cb5a315d32485acf04b8d6f7d0fb6e5fa..2f1b506c439249462b9740ff69e7553a37c45943 100644
--- a/drivers/iio/adc/ad7173.c
+++ b/drivers/iio/adc/ad7173.c
@@ -35,6 +35,7 @@
#include <linux/units.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>
@@ -102,6 +103,7 @@
#define AD7173_GPIO_PDSW BIT(14)
#define AD7173_GPIO_OP_EN2_3 BIT(13)
+#define AD4111_GPIO_GP_OW_EN BIT(12)
#define AD7173_GPIO_MUX_IO BIT(12)
#define AD7173_GPIO_SYNC_EN BIT(11)
#define AD7173_GPIO_ERR_EN BIT(10)
@@ -149,6 +151,7 @@
#define AD7173_FILTER_ODR0_MASK GENMASK(5, 0)
#define AD7173_MAX_CONFIGS 8
+#define AD4111_OW_DET_THRSH_MV 300
#define AD7173_MODE_CAL_INT_ZERO 0x4 /* Internal Zero-Scale Calibration */
#define AD7173_MODE_CAL_INT_FULL 0x5 /* Internal Full-Scale Calibration */
@@ -181,11 +184,15 @@ struct ad7173_device_info {
bool has_int_ref;
bool has_ref2;
bool has_internal_fs_calibration;
+ bool has_openwire_det;
bool higher_gpio_bits;
u8 num_gpios;
};
struct ad7173_channel_config {
+ /* Openwire detection threshold */
+ unsigned int openwire_thrsh_raw;
+ int openwire_comp_chan;
u8 cfg_slot;
bool live;
@@ -202,6 +209,7 @@ struct ad7173_channel {
unsigned int chan_reg;
unsigned int ain;
struct ad7173_channel_config cfg;
+ bool openwire_det_en;
};
struct ad7173_state {
@@ -280,6 +288,7 @@ static const struct ad7173_device_info ad4111_device_info = {
.has_current_inputs = true,
.has_int_ref = true,
.has_internal_fs_calibration = true,
+ .has_openwire_det = true,
.clock = 2 * HZ_PER_MHZ,
.sinc5_data_rates = ad7173_sinc5_data_rates,
.num_sinc5_data_rates = ARRAY_SIZE(ad7173_sinc5_data_rates),
@@ -616,6 +625,69 @@ static int ad7173_calibrate_all(struct ad7173_state *st, struct iio_dev *indio_d
return 0;
}
+/* Associative array of channel pairs for openwire detection
+ * The array is indexed by ain and gives the associated channel pair
+ * to perform the openwire detection with
+ * the channel pair [0] is for non differential and pair [1]
+ * is for differential inputs
+ */
+static int openwire_ain_to_channel_pair[][2][2] = {
+ [0] = { {0, 15}, {1, 2} },
+ [1] = { {1, 2}, {2, 1} },
+ [2] = { {3, 4}, {5, 6} },
+ [3] = { {5, 6}, {6, 5} },
+ [4] = { {7, 8}, {9, 10} },
+ [5] = { {9, 10}, {10, 9} },
+ [6] = { {11, 12}, {13, 14} },
+ [7] = { {13, 14}, {14, 13} },
+};
+
+/* Openwire detection on ad4111 works by running the same input measurement
+ * on two different channels and compare if the difference between the two
+ * measurements exceeds a certain value (typical 300mV)
+ */
+static void ad4111_openwire_event(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct ad7173_state *st = iio_priv(indio_dev);
+ struct ad7173_channel *adchan = &st->channels[chan->address];
+ struct ad7173_channel_config *cfg = &adchan->cfg;
+ int ret, val1, val2;
+
+ ret = regmap_set_bits(st->reg_gpiocon_regmap, AD7173_REG_GPIO, AD4111_GPIO_GP_OW_EN);
+ if (ret)
+ return;
+
+ adchan->cfg.openwire_comp_chan =
+ openwire_ain_to_channel_pair[chan->channel][chan->differential][0];
+
+ ret = ad_sigma_delta_single_conversion(indio_dev, chan, &val1);
+ if (ret < 0)
+ goto out;
+
+ adchan->cfg.openwire_comp_chan =
+ openwire_ain_to_channel_pair[chan->channel][chan->differential][1];
+
+ ret = ad_sigma_delta_single_conversion(indio_dev, chan, &val2);
+ if (ret < 0)
+ goto out;
+
+ if (abs(val1 - val2) > cfg->openwire_thrsh_raw)
+ iio_push_event(indio_dev,
+ IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, chan->address,
+ IIO_EV_TYPE_OPENWIRE, IIO_EV_DIR_RISING),
+ iio_get_time_ns(indio_dev));
+ else
+ iio_push_event(indio_dev,
+ IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, chan->address,
+ IIO_EV_TYPE_OPENWIRE, IIO_EV_DIR_FALLING),
+ iio_get_time_ns(indio_dev));
+
+out:
+ adchan->cfg.openwire_comp_chan = -1;
+ regmap_clear_bits(st->reg_gpiocon_regmap, AD7173_REG_GPIO, AD4111_GPIO_GP_OW_EN);
+}
+
static int ad7173_mask_xlate(struct gpio_regmap *gpio, unsigned int base,
unsigned int offset, unsigned int *reg,
unsigned int *mask)
@@ -813,6 +885,9 @@ static int ad7173_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
FIELD_PREP(AD7173_CH_SETUP_SEL_MASK, st->channels[channel].cfg.cfg_slot) |
st->channels[channel].ain;
+ if (st->channels[channel].cfg.openwire_comp_chan >= 0)
+ channel = st->channels[channel].cfg.openwire_comp_chan;
+
return ad_sd_write_reg(&st->sd, AD7173_REG_CH(channel), 2, val);
}
@@ -861,6 +936,11 @@ static int ad7173_disable_all(struct ad_sigma_delta *sd)
static int ad7173_disable_one(struct ad_sigma_delta *sd, unsigned int chan)
{
+ struct ad7173_state *st = ad_sigma_delta_to_ad7173(sd);
+
+ if (st->channels[chan].cfg.openwire_comp_chan >= 0)
+ chan = st->channels[chan].cfg.openwire_comp_chan;
+
return ad_sd_write_reg(sd, AD7173_REG_CH(chan), 2, 0);
}
@@ -968,6 +1048,9 @@ static int ad7173_read_raw(struct iio_dev *indio_dev,
if (ret < 0)
return ret;
+ if (ch->openwire_det_en)
+ ad4111_openwire_event(indio_dev, chan);
+
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
@@ -1112,12 +1195,71 @@ static int ad7173_debug_reg_access(struct iio_dev *indio_dev, unsigned int reg,
return ad_sd_write_reg(&st->sd, reg, reg_size, writeval);
}
+static int ad7173_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 ad7173_state *st = iio_priv(indio_dev);
+ struct ad7173_channel *adchan = &st->channels[chan->address];
+
+ adchan->openwire_det_en = state;
+
+ return 0;
+}
+
+static int ad7173_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)
+{
+ struct ad7173_state *st = iio_priv(indio_dev);
+ struct ad7173_channel *adchan = &st->channels[chan->address];
+
+ switch (info) {
+ case IIO_EV_INFO_VALUE:
+ adchan->cfg.openwire_thrsh_raw = val;
+ return 0;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ad7173_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 ad7173_state *st = iio_priv(indio_dev);
+ struct ad7173_channel *adchan = &st->channels[chan->address];
+
+ switch (info) {
+ case IIO_EV_INFO_VALUE:
+ *val = adchan->cfg.openwire_thrsh_raw;
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_event_spec ad4111_events[] = {
+ {
+ .type = IIO_EV_TYPE_OPENWIRE,
+ .dir = IIO_EV_DIR_EITHER,
+ .mask_separate = BIT(IIO_EV_INFO_VALUE),
+ .mask_shared_by_all = BIT(IIO_EV_INFO_ENABLE),
+ },
+};
+
static const struct iio_info ad7173_info = {
.read_raw = &ad7173_read_raw,
.write_raw = &ad7173_write_raw,
.debugfs_reg_access = &ad7173_debug_reg_access,
.validate_trigger = ad_sd_validate_trigger,
.update_scan_mode = ad7173_update_scan_mode,
+ .write_event_config = ad7173_write_event_config,
+ .write_event_value = ad7173_write_event_value,
+ .read_event_value = ad7173_read_event_value,
};
static const struct iio_scan_type ad4113_scan_type = {
@@ -1321,6 +1463,15 @@ static int ad7173_validate_reference(struct ad7173_state *st, int ref_sel)
return 0;
}
+static int ad7173_validate_openwire_ain_inputs(struct ad7173_state *st, bool differential,
+ unsigned int ain0, unsigned int ain1)
+{
+ if (differential)
+ return (ain0 % 2) ? (ain0 - 1) == ain1 : (ain0 + 1) == ain1;
+
+ return ain1 == AD4111_VINCOM_INPUT;
+}
+
static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
{
struct ad7173_channel *chans_st_arr, *chan_st_priv;
@@ -1375,6 +1526,7 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
chan_st_priv->cfg.bipolar = false;
chan_st_priv->cfg.input_buf = st->info->has_input_buf;
chan_st_priv->cfg.ref_sel = AD7173_SETUP_REF_SEL_INT_REF;
+ chan_st_priv->cfg.openwire_comp_chan = -1;
st->adc_mode |= AD7173_ADC_MODE_REF_EN;
if (st->info->data_reg_only_16bit)
chan_arr[chan_index].scan_type = ad4113_scan_type;
@@ -1442,6 +1594,7 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
chan_st_priv->chan_reg = chan_index;
chan_st_priv->cfg.input_buf = st->info->has_input_buf;
chan_st_priv->cfg.odr = 0;
+ chan_st_priv->cfg.openwire_comp_chan = -1;
chan_st_priv->cfg.bipolar = fwnode_property_read_bool(child, "bipolar");
if (chan_st_priv->cfg.bipolar)
@@ -1456,6 +1609,17 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
chan_st_priv->cfg.input_buf = st->info->has_input_buf;
chan->channel2 = ain[1];
chan_st_priv->ain = AD7173_CH_ADDRESS(ain[0], ain[1]);
+ if (st->info->has_openwire_det &&
+ ad7173_validate_openwire_ain_inputs(st, chan->differential, ain[0], ain[1])) {
+ chan->event_spec = ad4111_events;
+ chan->num_event_specs = ARRAY_SIZE(ad4111_events);
+ chan_st_priv->cfg.openwire_thrsh_raw =
+ BIT(chan->scan_type.realbits - !!(chan_st_priv->cfg.bipolar))
+ * AD4111_OW_DET_THRSH_MV
+ / ad7173_get_ref_voltage_milli(st, chan_st_priv->cfg.ref_sel);
+ if (chan->channel < st->info->num_voltage_in_div)
+ chan_st_priv->cfg.openwire_thrsh_raw /= AD4111_DIVIDER_RATIO;
+ }
}
if (st->info->data_reg_only_16bit)
--
2.47.1
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