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Message-Id: <20250818183214.380847-7-bcollins@kernel.org>
Date: Mon, 18 Aug 2025 14:32:14 -0400
From: Ben Collins <bcollins@...nel.org>
To: Jonathan Cameron <jic23@...nel.org>,
David Lechner <dlechner@...libre.com>,
Nuno Sá <nuno.sa@...log.com>,
Andy Shevchenko <andy@...nel.org>
Cc: Ben Collins <bcollins@...ter.com>,
linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] iio: mcp9600: Add support for IIR filter
From: Ben Collins <bcollins@...ter.com>
MCP9600 supports an IIR filter with 7 levels. Add IIR attribute
to allow get/set of this value.
Use a filter_type[none, ema] for enabling the IIR filter.
Signed-off-by: Ben Collins <bcollins@...ter.com>
---
drivers/iio/temperature/mcp9600.c | 157 ++++++++++++++++++++++++++++++
1 file changed, 157 insertions(+)
diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
index 9b017820efc1..0ec47cbeb88c 100644
--- a/drivers/iio/temperature/mcp9600.c
+++ b/drivers/iio/temperature/mcp9600.c
@@ -31,6 +31,7 @@
#define MCP9600_STATUS_ALERT(x) BIT(x)
#define MCP9600_SENSOR_CFG 0x05
#define MCP9600_SENSOR_TYPE_MASK GENMASK(6, 4)
+#define MCP9600_FILTER_MASK GENMASK(2, 0)
#define MCP9600_ALERT_CFG1 0x08
#define MCP9600_ALERT_CFG(x) (MCP9600_ALERT_CFG1 + (x - 1))
#define MCP9600_ALERT_CFG_ENABLE BIT(0)
@@ -94,6 +95,27 @@ static const int mcp9600_tc_types[] = {
[THERMOCOUPLE_TYPE_R] = 'R',
};
+enum mcp9600_filter {
+ MCP9600_FILTER_TYPE_NONE,
+ MCP9600_FILTER_TYPE_EMA,
+};
+
+static const char * const mcp9600_filter_type[] = {
+ [MCP9600_FILTER_TYPE_NONE] = "none",
+ [MCP9600_FILTER_TYPE_EMA] = "ema",
+};
+
+static const int mcp_iir_coefficients_avail[7][2] = {
+ /* Level 0 is no filter */
+ { 0, 524549 },
+ { 0, 243901 },
+ { 0, 119994 },
+ { 0, 59761 },
+ { 0, 29851 },
+ { 0, 14922 },
+ { 0, 7461 },
+};
+
static const struct iio_event_spec mcp9600_events[] = {
{
.type = IIO_EV_TYPE_THRESH,
@@ -118,7 +140,11 @@ static const struct iio_event_spec mcp9600_events[] = {
.address = MCP9600_HOT_JUNCTION, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE) | \
+ BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) | \
BIT(IIO_CHAN_INFO_SCALE), \
+ .info_mask_separate_available = \
+ BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY), \
+ .ext_info = mcp9600_ext_filter, \
.event_spec = &mcp9600_events[hj_ev_spec_off], \
.num_event_specs = hj_num_ev, \
}, \
@@ -134,6 +160,26 @@ static const struct iio_event_spec mcp9600_events[] = {
}, \
}
+static int mcp9600_get_filter(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan);
+static int mcp9600_set_filter(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ unsigned int mode);
+
+static const struct iio_enum mcp9600_filter_enum = {
+ .items = mcp9600_filter_type,
+ .num_items = ARRAY_SIZE(mcp9600_filter_type),
+ .get = mcp9600_get_filter,
+ .set = mcp9600_set_filter,
+};
+
+static const struct iio_chan_spec_ext_info mcp9600_ext_filter[] = {
+ IIO_ENUM("filter_type", IIO_SHARED_BY_ALL, &mcp9600_filter_enum),
+ IIO_ENUM_AVAILABLE("filter_type", IIO_SHARED_BY_ALL,
+ &mcp9600_filter_enum),
+ { }
+};
+
static const struct iio_chan_spec mcp9600_channels[][2] = {
MCP9600_CHANNELS(0, 0, 0, 0), /* Alerts: - - - - */
MCP9600_CHANNELS(1, 0, 0, 0), /* Alerts: 1 - - - */
@@ -161,6 +207,8 @@ struct mcp_chip_info {
struct mcp9600_data {
struct i2c_client *client;
u32 thermocouple_type;
+ /* Filter enabled is 1-7, with 0 being off (filter_type none) */
+ u8 filter_level;
};
static int mcp9600_read(struct mcp9600_data *data,
@@ -191,13 +239,45 @@ static int mcp9600_read_raw(struct iio_dev *indio_dev,
if (ret)
return ret;
return IIO_VAL_INT;
+
case IIO_CHAN_INFO_SCALE:
*val = 62;
*val2 = 500000;
return IIO_VAL_INT_PLUS_MICRO;
+
case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
*val = mcp9600_tc_types[data->thermocouple_type];
return IIO_VAL_CHAR;
+
+ case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+ if (data->filter_level == 0)
+ return -EINVAL;
+
+ *val = mcp_iir_coefficients_avail[data->filter_level - 1][0];
+ *val2 = mcp_iir_coefficients_avail[data->filter_level - 1][1];
+ return IIO_VAL_INT_PLUS_MICRO;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int mcp9600_read_avail(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int **vals, int *type, int *length,
+ long mask)
+{
+ struct mcp9600_data *data = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+ if (data->filter_level == 0)
+ return -EINVAL;
+
+ *vals = (int *)mcp_iir_coefficients_avail;
+ *type = IIO_VAL_INT_PLUS_MICRO;
+ *length = 2 * ARRAY_SIZE(mcp_iir_coefficients_avail);
+ return IIO_AVAIL_LIST;
default:
return -EINVAL;
}
@@ -211,6 +291,7 @@ static int mcp9600_config(struct mcp9600_data *data)
cfg = FIELD_PREP(MCP9600_SENSOR_TYPE_MASK,
mcp9600_type_map[data->thermocouple_type]);
+ FIELD_MODIFY(MCP9600_FILTER_MASK, &cfg, data->filter_level);
ret = i2c_smbus_write_byte_data(client, MCP9600_SENSOR_CFG, cfg);
if (ret < 0) {
@@ -221,6 +302,79 @@ static int mcp9600_config(struct mcp9600_data *data)
return 0;
}
+static int mcp9600_write_raw_get_fmt(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ long mask)
+{
+ switch (mask) {
+ case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+ return IIO_VAL_INT_PLUS_MICRO;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int mcp9600_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct mcp9600_data *data = iio_priv(indio_dev);
+ int i;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+ for (i = 0; i < ARRAY_SIZE(mcp_iir_coefficients_avail); i++) {
+ if (mcp_iir_coefficients_avail[i][0] == val &&
+ mcp_iir_coefficients_avail[i][1] == val2)
+ break;
+ }
+
+ if (i == ARRAY_SIZE(mcp_iir_coefficients_avail))
+ return -EINVAL;
+
+ data->filter_level = i + 1;
+ return mcp9600_config(data);
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int mcp9600_get_filter(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan)
+{
+ struct mcp9600_data *data = iio_priv(indio_dev);
+
+ if (data->filter_level == 0)
+ return MCP9600_FILTER_TYPE_NONE;
+
+ return MCP9600_FILTER_TYPE_EMA;
+}
+
+static int mcp9600_set_filter(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ unsigned int mode)
+{
+ struct mcp9600_data *data = iio_priv(indio_dev);
+
+ switch (mode) {
+ case MCP9600_FILTER_TYPE_NONE:
+ data->filter_level = 0;
+ return mcp9600_config(data);
+
+ case MCP9600_FILTER_TYPE_EMA:
+ if (data->filter_level == 0) {
+ /* Minimum filter by default */
+ data->filter_level = 1;
+ return mcp9600_config(data);
+ }
+ return 0;
+
+ default:
+ return -EINVAL;
+ }
+}
+
static int mcp9600_get_alert_index(int channel2, enum iio_event_direction dir)
{
if (channel2 == IIO_MOD_TEMP_AMBIENT) {
@@ -358,6 +512,9 @@ static int mcp9600_write_thresh(struct iio_dev *indio_dev,
static const struct iio_info mcp9600_info = {
.read_raw = mcp9600_read_raw,
+ .read_avail = mcp9600_read_avail,
+ .write_raw = mcp9600_write_raw,
+ .write_raw_get_fmt = mcp9600_write_raw_get_fmt,
.read_event_config = mcp9600_read_event_config,
.write_event_config = mcp9600_write_event_config,
.read_event_value = mcp9600_read_thresh,
--
2.39.5
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