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Date: Tue, 29 Oct 2019 17:45:35 +0100
From: Pascal Paillet <p.paillet@...com>
To: <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>,
<robh+dt@...nel.org>, <mark.rutland@....com>,
<rui.zhang@...el.com>, <edubezval@...il.com>,
<daniel.lezcano@...aro.org>, <amit.kucheria@...durent.com>,
<david.hernandezsanchez@...com>,
<wsa+renesas@...g-engineering.com>,
<linux-stm32@...md-mailman.stormreply.com>,
<linux-arm-kernel@...ts.infradead.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-pm@...r.kernel.org>
CC: <p.paillet@...com>
Subject: [PATCH 2/4] thermal: stm32: fix IRQ flood on low threshold
Fix IRQ flood on low threshold by too ways:
- improve temperature reading resolution,
- add an hysteresis to the low threshold: on low threshold interrupt,
it is not possible to get the temperature value that has fired the
interrupt. The time to acquire a new value is enough for the CPU to
become hotter than the current low threshold.
Signed-off-by: Pascal Paillet <p.paillet@...com>
Change-Id: I3b63b8aab38fd651a165c4e69a2d090b3c6f5db3
---
drivers/thermal/st/stm_thermal.c | 73 +++++++++-----------------------
1 file changed, 19 insertions(+), 54 deletions(-)
diff --git a/drivers/thermal/st/stm_thermal.c b/drivers/thermal/st/stm_thermal.c
index 0aae1cc14235..4bc1bbece0de 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;
@@ -222,12 +216,8 @@ static int stm_thermal_calibration(struct stm_thermal_sensor *sensor)
if (!clk_freq)
return -EINVAL;
- prescaler = 0;
- clk_freq /= ONE_MHZ;
- if (clk_freq) {
- while (prescaler <= clk_freq)
- prescaler++;
- }
+ /* calculate divider for maximum 1MHz PCLK */
+ prescaler = clk_freq / ONE_MHZ + 1;
value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
@@ -235,7 +225,7 @@ static int stm_thermal_calibration(struct stm_thermal_sensor *sensor)
value &= ~HSREF_CLK_DIV_MASK;
/* Set prescaler. pclk_freq/prescaler < 1MHz */
- value |= (prescaler << HSREF_CLK_DIV_POS);
+ value |= (prescaler << HSREF_CLK_DIV_POS) & HSREF_CLK_DIV_MASK;
/* Select PCLK as reference clock */
value &= ~REFCLK_SEL;
@@ -289,28 +279,16 @@ 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;
@@ -320,42 +298,28 @@ static int stm_thermal_calculate_threshold(struct stm_thermal_sensor *sensor,
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;
- dev_dbg(sensor->dev, "temperature = %d millicelsius", *temp);
+ dev_dbg(sensor->dev, "periods=0x%x t=%d mC", periods, *temp);
return 0;
}
@@ -379,7 +343,8 @@ static int stm_thermal_set_trips(void *data, int low, int high)
if (low > -INT_MAX) {
sensor->low_en = 1;
- ret = stm_thermal_calculate_threshold(sensor, low, &th);
+ /* add 0.5 of hysteresis due to measurement error */
+ ret = stm_thermal_calculate_threshold(sensor, low - 500, &th);
if (ret)
return ret;
--
2.17.1
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