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| author | Liam Beguin <liambeguin@gmail.com> | 2022-02-12 21:57:36 -0500 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-02-28 10:22:24 +0000 |
| commit | 278fe1d2d3a70e45267098024dc27390d8a0a157 (patch) | |
| tree | 7e606dd13b75b7edb6dc1c0c07f97ca4fa6d4658 | |
| parent | 8e74a48d17d509bf605e64252f38550b1a9cc376 (diff) | |
| download | iio-278fe1d2d3a70e45267098024dc27390d8a0a157.tar.gz | |
iio: afe: rescale: add RTD temperature sensor support
An RTD (Resistance Temperature Detector) is a kind of temperature
sensor used to get a linear voltage to temperature reading within a
give range (usually 0 to 100 degrees Celsius). Common types of RTDs
include PT100, PT500, and PT1000.
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/20220213025739.2561834-8-liambeguin@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
| -rw-r--r-- | drivers/iio/afe/iio-rescale.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c index 46947c68d3a99..e31a934355360 100644 --- a/drivers/iio/afe/iio-rescale.c +++ b/drivers/iio/afe/iio-rescale.c @@ -394,10 +394,52 @@ static int rescale_voltage_divider_props(struct device *dev, return 0; } +static int rescale_temp_sense_rtd_props(struct device *dev, + struct rescale *rescale) +{ + u32 factor; + u32 alpha; + u32 iexc; + u32 tmp; + int ret; + u32 r0; + + ret = device_property_read_u32(dev, "excitation-current-microamp", + &iexc); + if (ret) { + dev_err(dev, "failed to read excitation-current-microamp: %d\n", + ret); + return ret; + } + + 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; + } + + ret = device_property_read_u32(dev, "r-naught-ohms", &r0); + if (ret) { + dev_err(dev, "failed to read r-naught-ohms: %d\n", ret); + return ret; + } + + tmp = r0 * iexc * alpha / 1000000; + factor = gcd(tmp, 1000000); + rescale->numerator = 1000000 / factor; + rescale->denominator = tmp / factor; + + rescale->offset = -1 * ((r0 * iexc) / 1000); + + return 0; +} + enum rescale_variant { CURRENT_SENSE_AMPLIFIER, CURRENT_SENSE_SHUNT, VOLTAGE_DIVIDER, + TEMP_SENSE_RTD, }; static const struct rescale_cfg rescale_cfg[] = { @@ -413,6 +455,10 @@ static const struct rescale_cfg rescale_cfg[] = { .type = IIO_VOLTAGE, .props = rescale_voltage_divider_props, }, + [TEMP_SENSE_RTD] = { + .type = IIO_TEMP, + .props = rescale_temp_sense_rtd_props, + }, }; static const struct of_device_id rescale_match[] = { @@ -422,6 +468,8 @@ static const struct of_device_id rescale_match[] = { .data = &rescale_cfg[CURRENT_SENSE_SHUNT], }, { .compatible = "voltage-divider", .data = &rescale_cfg[VOLTAGE_DIVIDER], }, + { .compatible = "temperature-sense-rtd", + .data = &rescale_cfg[TEMP_SENSE_RTD], }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, rescale_match); |