[PATCH v9 12/14] iio: afe: rescale: add temperature transducers
From: Liam Beguin <hidden>
Date: 2021-11-15 03:47:35
Also in:
linux-iio, lkml
Subsystem:
iio subsystem and drivers, iio unit converter, the rest · Maintainers:
Jonathan Cameron, Peter Rosin, Linus Torvalds
From: Liam Beguin <redacted> A temperature transducer is a device that converts a thermal quantity into any other physical quantity. This patch add support for temperature to voltage (like the LTC2997) and temperature to current (like the AD590) linear transducers. In both cases these are assumed to be connected to a voltage ADC. Signed-off-by: Liam Beguin <redacted> --- drivers/iio/afe/iio-rescale.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index ea162ba2a674..6bdcf6e139c7 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c@@ -422,11 +422,37 @@ static int rescale_temp_sense_rtd_props(struct device *dev, return 0; } +static int rescale_temp_transducer_props(struct device *dev, + struct rescale *rescale) +{ + s32 offset = 0; + s32 sense = 1; + s32 alpha; + int ret; + + device_property_read_u32(dev, "sense-offset-millicelsius", &offset); + device_property_read_u32(dev, "sense-resistor-ohms", &sense); + ret = device_property_read_u32(dev, "alpha-ppm-per-celsius", &alpha); + if (ret) { + dev_err(dev, "failed to read alpha-ppm-per-celsius: %d\n", ret); + return ret; + } + + rescale->numerator = 1000000; + rescale->denominator = alpha * sense; + + rescale->offset = div_s64((s64)offset * rescale->denominator, + rescale->numerator); + + return 0; +} + enum rescale_variant { CURRENT_SENSE_AMPLIFIER, CURRENT_SENSE_SHUNT, VOLTAGE_DIVIDER, TEMP_SENSE_RTD, + TEMP_TRANSDUCER, }; static const struct rescale_cfg rescale_cfg[] = {
@@ -446,6 +472,10 @@ static const struct rescale_cfg rescale_cfg[] = { .type = IIO_TEMP, .props = rescale_temp_sense_rtd_props, }, + [TEMP_TRANSDUCER] = { + .type = IIO_TEMP, + .props = rescale_temp_transducer_props, + }, }; static const struct of_device_id rescale_match[] = {
@@ -457,6 +487,8 @@ static const struct of_device_id rescale_match[] = { .data = &rescale_cfg[VOLTAGE_DIVIDER], }, { .compatible = "temperature-sense-rtd", .data = &rescale_cfg[TEMP_SENSE_RTD], }, + { .compatible = "temperature-transducer", + .data = &rescale_cfg[TEMP_TRANSDUCER], }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, rescale_match);
--
2.32.0.452.g940fe202adcb