@@ -346,10 +346,52 @@ 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[] = {
@@ -365,6 +407,10 @@ 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[] = {
@@ -374,6 +420,8 @@ 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);