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thermal: stm32: Improve temperature computing

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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>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200110101605.24984-6-p.paillet@st.com
This commit is contained in:
Pascal Paillet 2020-01-10 11:16:04 +01:00 committed by Daniel Lezcano
parent dd4c3919a8
commit 9d8593f22e
1 changed files with 14 additions and 44 deletions
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58
drivers/thermal/st/stm_thermal.c
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@ -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;
}