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-rw-r--r--drivers/thermal/imx_thermal.c26
1 files changed, 11 insertions, 15 deletions
diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
index 41e15cf5ffd7..a67781b7a0b2 100644
--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -70,10 +70,6 @@ enum imx_thermal_trip {
#define IMX_POLLING_DELAY 2000 /* millisecond */
#define IMX_PASSIVE_DELAY 1000
-#define FACTOR0 10000000
-#define FACTOR1 15976
-#define FACTOR2 4297157
-
#define TEMPMON_IMX6Q 1
#define TEMPMON_IMX6SX 2
@@ -350,7 +346,7 @@ static struct thermal_zone_device_ops imx_tz_ops = {
static int imx_init_calib(struct platform_device *pdev, u32 ocotp_ana1)
{
struct imx_thermal_data *data = platform_get_drvdata(pdev);
- int t1, n1;
+ int n1;
u64 temp64;
if (ocotp_ana1 == 0 || ocotp_ana1 == ~0) {
@@ -365,25 +361,25 @@ static int imx_init_calib(struct platform_device *pdev, u32 ocotp_ana1)
* To find the actual temperature T, the following formula has to be used
* when reading value n from the sensor:
*
- * T = T1 + (N - N1) / (0.4297157 - 0.0015976 * N1) °C
- * = [T1 - N1 / (0.4297157 - 0.0015976 * N1) °C] + N / (0.4297157 - 0.0015976 * N1) °C
- * = [T1 + N1 / (0.0015976 * N1 - 0.4297157) °C] - N / (0.0015976 * N1 - 0.4297157) °C
+ * T = T1 + (N - N1) / (0.4148468 - 0.0015423 * N1) °C + 3.580661 °C
+ * = [T1' - N1 / (0.4148468 - 0.0015423 * N1) °C] + N / (0.4148468 - 0.0015423 * N1) °C
+ * = [T1' + N1 / (0.0015423 * N1 - 0.4148468) °C] - N / (0.0015423 * N1 - 0.4148468) °C
* = c2 - c1 * N
*
* with
*
- * c1 = 1 / (0.0015976 * N1 - 0.4297157) °C
- * c2 = T1 + N1 / (0.0015976 * N1 - 0.4297157) °C
- * = T1 + N1 * C1
+ * T1' = 28.580661 °C
+ * c1 = 1 / (0.0015423 * N1 - 0.4297157) °C
+ * c2 = T1' + N1 / (0.0015423 * N1 - 0.4148468) °C
+ * = T1' + N1 * c1
*/
n1 = ocotp_ana1 >> 20;
- t1 = 25; /* °C */
- temp64 = FACTOR0; /* 10^7 for FACTOR1 and FACTOR2 */
+ temp64 = 10000000; /* use 10^7 as fixed point constant for values in formula */
temp64 *= 1000; /* to get result in °mC */
- do_div(temp64, FACTOR1 * n1 - FACTOR2);
+ do_div(temp64, 15423 * n1 - 4148468);
data->c1 = temp64;
- data->c2 = n1 * data->c1 + 1000 * t1;
+ data->c2 = n1 * data->c1 + 28581;
return 0;
}

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