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From: Ben Collins Date: Mon, 25 Aug 2025 20:10:06 -0400 Subject: [PATCH v7 4/5] iio: mcp9600: Add support for IIR filter Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250825-mcp9600-iir-v7-4-2ba676a52589@kernel.org> References: <20250825-mcp9600-iir-v7-0-2ba676a52589@kernel.org> In-Reply-To: <20250825-mcp9600-iir-v7-0-2ba676a52589@kernel.org> To: Jonathan Cameron , David Lechner , =?utf-8?q?Nuno_S=C3=A1?= , Andy Shevchenko , Antoniu Miclaus , Lars-Peter Clausen , Michael Hennerich Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Collins X-Migadu-Flow: FLOW_OUT MCP9600 supports an IIR filter with 7 levels. Add IIR attribute to allow get/set of this value. Use filter_type[none, ema] for enabling the IIR filter. Signed-off-by: Ben Collins --- drivers/iio/temperature/mcp9600.c | 147 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 147 insertions(+) diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c index aa42c2b1a369edbd36e0d6d6d1738ed0069fd990..d3309e30628ae5cdc74378403952ba285990f4c0 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, @@ -119,6 +141,8 @@ struct mcp_chip_info { struct mcp9600_data { struct i2c_client *client; u32 thermocouple_type; + int filter_level; + int filter_enabled; }; static int mcp9600_config(struct mcp9600_data *data) @@ -129,6 +153,9 @@ static int mcp9600_config(struct mcp9600_data *data) cfg = FIELD_PREP(MCP9600_SENSOR_TYPE_MASK, mcp9600_type_map[data->thermocouple_type]); + /* The chip understands 0 as "none", and 1-7 as ema filter levels. */ + if (data->filter_enabled) + FIELD_MODIFY(MCP9600_FILTER_MASK, &cfg, data->filter_level + 1); ret = i2c_smbus_write_byte_data(client, MCP9600_SENSOR_CFG, cfg); if (ret < 0) { @@ -146,7 +173,11 @@ static int mcp9600_config(struct mcp9600_data *data) .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, \ }, \ @@ -162,6 +193,57 @@ static int mcp9600_config(struct mcp9600_data *data) }, \ } +static int mcp9600_get_filter(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan) +{ + struct mcp9600_data *data = iio_priv(indio_dev); + + return data->filter_enabled ? MCP9600_FILTER_TYPE_EMA : + MCP9600_FILTER_TYPE_NONE; +} + +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); + int new_type; + + switch (mode) { + case MCP9600_FILTER_TYPE_NONE: + new_type = 0; + break; + + case MCP9600_FILTER_TYPE_EMA: + new_type = 1; + break; + + default: + return -EINVAL; + } + + /* Do not reset the filter if we don't need to. */ + if (data->filter_enabled == new_type) + return 0; + + data->filter_enabled = new_type; + return mcp9600_config(data); +} + +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 - - - */ @@ -216,6 +298,69 @@ static int mcp9600_read_raw(struct iio_dev *indio_dev, 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_enabled) + return IIO_VAL_EMPTY; + + *val = mcp_iir_coefficients_avail[data->filter_level][0]; + *val2 = mcp_iir_coefficients_avail[data->filter_level][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_enabled) { + *type = IIO_VAL_EMPTY; + return IIO_AVAIL_LIST; + } + + *vals = (int *)mcp_iir_coefficients_avail; + *length = 2 * ARRAY_SIZE(mcp_iir_coefficients_avail); + *type = IIO_VAL_INT_PLUS_MICRO; + return IIO_AVAIL_LIST; + 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: + if (!data->filter_enabled) + return -EINVAL; + + 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; + + /* Do not reset the filter if there's no change. */ + if (data->filter_level == i) + return 0; + + data->filter_level = i; + return mcp9600_config(data); + default: return -EINVAL; } @@ -358,6 +503,8 @@ 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, .read_event_config = mcp9600_read_event_config, .write_event_config = mcp9600_write_event_config, .read_event_value = mcp9600_read_thresh, -- 2.39.5