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Subject[PATCH_V3 5/6] thermal: stm32: improve temperature computing
Date
Change the way of computing to avoid rounds by 1 or 2 degrees.
Also simplify the sampling time management that is hard-coded
to maximum value during probe.

Signed-off-by: Pascal Paillet <p.paillet@st.com>
---
drivers/thermal/st/stm_thermal.c | 58 ++++++++------------------------
1 file changed, 14 insertions(+), 44 deletions(-)

diff --git a/drivers/thermal/st/stm_thermal.c b/drivers/thermal/st/stm_thermal.c
index 29e7ee89adf6..aaf25ca2f118 100644
--- a/drivers/thermal/st/stm_thermal.c
+++ b/drivers/thermal/st/stm_thermal.c
@@ -59,7 +59,6 @@

/* Less significant bit position definitions */
#define TS1_T0_POS 16
-#define TS1_SMP_TIME_POS 16
#define TS1_HITTHD_POS 16
#define TS1_LITTHD_POS 0
#define HSREF_CLK_DIV_POS 24
@@ -83,15 +82,10 @@
#define ONE_MHZ 1000000
#define POLL_TIMEOUT 5000
#define STARTUP_TIME 40
-#define TS1_T0_VAL0 30
-#define TS1_T0_VAL1 130
+#define TS1_T0_VAL0 30000 /* 30 celsius */
+#define TS1_T0_VAL1 130000 /* 130 celsius */
#define NO_HW_TRIG 0
-
-/* The Thermal Framework expects millidegrees */
-#define mcelsius(temp) ((temp) * 1000)
-
-/* The Sensor expects oC degrees */
-#define celsius(temp) ((temp) / 1000)
+#define SAMPLING_TIME 15

struct stm_thermal_sensor {
struct device *dev;
@@ -280,27 +274,17 @@ static int stm_thermal_calculate_threshold(struct stm_thermal_sensor *sensor,
int temp, u32 *th)
{
int freqM;
- u32 sampling_time;
-
- /* Retrieve the number of periods to sample */
- sampling_time = (readl_relaxed(sensor->base + DTS_CFGR1_OFFSET) &
- TS1_SMP_TIME_MASK) >> TS1_SMP_TIME_POS;

/* Figure out the CLK_PTAT frequency for a given temperature */
- freqM = ((temp - sensor->t0) * sensor->ramp_coeff)
- + sensor->fmt0;
-
- dev_dbg(sensor->dev, "%s: freqM for threshold = %d Hz",
- __func__, freqM);
+ freqM = ((temp - sensor->t0) * sensor->ramp_coeff) / 1000 +
+ sensor->fmt0;

/* Figure out the threshold sample number */
- *th = clk_get_rate(sensor->clk);
+ *th = clk_get_rate(sensor->clk) * SAMPLING_TIME / freqM;
if (!*th)
return -EINVAL;

- *th = *th / freqM;
-
- *th *= sampling_time;
+ dev_dbg(sensor->dev, "freqM=%d Hz, threshold=0x%x", freqM, *th);

return 0;
}
@@ -368,40 +352,26 @@ static int stm_thermal_set_trips(void *data, int low, int high)
static int stm_thermal_get_temp(void *data, int *temp)
{
struct stm_thermal_sensor *sensor = data;
- u32 sampling_time;
+ u32 periods;
int freqM, ret;

if (sensor->mode != THERMAL_DEVICE_ENABLED)
return -EAGAIN;

- /* Retrieve the number of samples */
- ret = readl_poll_timeout(sensor->base + DTS_DR_OFFSET, freqM,
- (freqM & TS1_MFREQ_MASK), STARTUP_TIME,
- POLL_TIMEOUT);
-
+ /* Retrieve the number of periods sampled */
+ ret = readl_relaxed_poll_timeout(sensor->base + DTS_DR_OFFSET, periods,
+ (periods & TS1_MFREQ_MASK),
+ STARTUP_TIME, POLL_TIMEOUT);
if (ret)
return ret;

- if (!freqM)
- return -ENODATA;
-
- /* Retrieve the number of periods sampled */
- sampling_time = (readl_relaxed(sensor->base + DTS_CFGR1_OFFSET) &
- TS1_SMP_TIME_MASK) >> TS1_SMP_TIME_POS;
-
- /* Figure out the number of samples per period */
- freqM /= sampling_time;
-
/* Figure out the CLK_PTAT frequency */
- freqM = clk_get_rate(sensor->clk) / freqM;
+ freqM = (clk_get_rate(sensor->clk) * SAMPLING_TIME) / periods;
if (!freqM)
return -EINVAL;

- dev_dbg(sensor->dev, "%s: freqM=%d\n", __func__, freqM);
-
/* Figure out the temperature in mili celsius */
- *temp = mcelsius(sensor->t0 + ((freqM - sensor->fmt0) /
- sensor->ramp_coeff));
+ *temp = (freqM - sensor->fmt0) * 1000 / sensor->ramp_coeff + sensor->t0;

return 0;
}
--
2.17.1
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