diff options
Diffstat (limited to 'drivers/hwmon/ntc_thermistor.c')
| -rw-r--r-- | drivers/hwmon/ntc_thermistor.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c index 18fd6f12ca16..cf26c44f2b88 100644 --- a/drivers/hwmon/ntc_thermistor.c +++ b/drivers/hwmon/ntc_thermistor.c @@ -13,6 +13,7 @@ #include <linux/err.h> #include <linux/of.h> #include <linux/of_device.h> +#include <linux/fixp-arith.h> #include <linux/platform_data/ntc_thermistor.h> @@ -549,15 +550,16 @@ static int get_temp_mc(struct ntc_data *data, unsigned int ohm) int temp; lookup_comp(data, ohm, &low, &high); - if (low == high) { - /* Unable to use linear approximation */ - temp = data->comp[low].temp_c * 1000; - } else { - temp = data->comp[low].temp_c * 1000 + - ((data->comp[high].temp_c - data->comp[low].temp_c) * - 1000 * ((int)ohm - (int)data->comp[low].ohm)) / - ((int)data->comp[high].ohm - (int)data->comp[low].ohm); - } + /* + * First multiplying the table temperatures with 1000 to get to + * millicentigrades (which is what we want) and then interpolating + * will give the best precision. + */ + temp = fixp_linear_interpolate(data->comp[low].ohm, + data->comp[low].temp_c * 1000, + data->comp[high].ohm, + data->comp[high].temp_c * 1000, + ohm); return temp; } |