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authorLiam Beguin <liambeguin@gmail.com>2022-02-13 05:57:37 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2022-02-28 13:22:24 +0300
commit03e7d21ee1a975311c2a2c6f1f31e45023af991c (patch)
treee5174c4be66d32533007dfed303187cb3001f591 /drivers/iio
parent278fe1d2d3a70e45267098024dc27390d8a0a157 (diff)
downloadlinux-03e7d21ee1a975311c2a2c6f1f31e45023af991c.tar.xz
iio: afe: rescale: add temperature transducers
A temperature transducer is a device that converts a thermal quantity into any other physical quantity. This patch adds 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 <liambeguin@gmail.com> Reviewed-by: Peter Rosin <peda@axentia.se> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20220213025739.2561834-9-liambeguin@gmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio')
-rw-r--r--drivers/iio/afe/iio-rescale.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index e31a93435536..7e511293d6d1 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -435,11 +435,37 @@ 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[] = {
@@ -459,6 +485,10 @@ 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[] = {
@@ -470,6 +500,8 @@ 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);