[PATCH v2 12/16] hwmon: (mr75203) modify the temperature equation

Eliav Farber
2022-08-17T05:44:29Z

Modify the equation and coefficients to convert the digital output to
temperature according to series 5 of the Moortec Embedded Temperature
Sensor (METS) datasheet:
T = G + H * (n / cal5 - 0.5) + J * F

The G, H and J coefficients are multiplied by 1000 to get the temperature
in milli-Celsius.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
drivers/hwmon/mr75203.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c
index e3191f590167..e500897585e4 100644
--- a/drivers/hwmon/mr75203.c
+++ b/drivers/hwmon/mr75203.c
@@ -102,9 +102,10 @@

#define PVT_POLL_DELAY_US 20
#define PVT_POLL_TIMEOUT_US 20000
-#define PVT_H_CONST 100000
-#define PVT_CAL5_CONST 2047
-#define PVT_G_CONST 40000
+#define PVT_H_CONST 60000
+#define PVT_G_CONST 200000
+#define PVT_J_CONST -100
+#define PVT_CAL5_CONST 4094
#define PVT_CONV_BITS 10
#define PVT_N_CONST 90
#define PVT_R_CONST 245805
@@ -158,7 +159,6 @@ static int pvt_read_temp(struct device *dev, u32 attr, int channel, long *val)
struct regmap *t_map = pvt->t_map;
u32 stat, nbs;
int ret;
- u64 tmp;

switch (attr) {
case hwmon_temp_input:
@@ -176,12 +176,13 @@ static int pvt_read_temp(struct device *dev, u32 attr, int channel, long *val)
nbs &= SAMPLE_DATA_MSK;

/*
- * Convert the register value to
- * degrees centigrade temperature
+ * Convert the register value to degrees centigrade temperature:
+ * T = G + H * (n / cal5 - 0.5) + J * F
*/
- tmp = nbs * PVT_H_CONST;
- do_div(tmp, PVT_CAL5_CONST);
- *val = tmp - PVT_G_CONST - pvt->ip_freq;
+ *val = PVT_G_CONST;
+ *val += PVT_H_CONST * nbs / PVT_CAL5_CONST;
+ *val -= PVT_H_CONST / 2;
+ *val += PVT_J_CONST * pvt->ip_freq / HZ_PER_MHZ;

return 0;
default:
@@ -313,7 +314,7 @@ static int pvt_init(struct pvt_device *pvt)
(key >> 1) << CLK_SYNTH_HI_SFT |
(key >> 1) << CLK_SYNTH_HOLD_SFT | CLK_SYNTH_EN;

- pvt->ip_freq = sys_freq * 100 / (key + 2);
+ pvt->ip_freq = clk_get_rate(pvt->clk) / (key + 2);

if (t_num) {
ret = regmap_write(t_map, SDIF_SMPL_CTRL, 0x0);
--
2.37.1