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thermal: armada: average over samples to avoid glitches 

Configure the sample frequency and number of averaged samples.

This is needed for two reasons:
1/ To be bootloader independent.
2/ To prepare the introduction of multi-sensors support by preventing
   inconsistencies when reading temperatures that could be a mean of
   samples took from different sensors.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
hifive-unleashed-5.1
Miquel Raynal 2018-07-16 16:41:49 +02:00 committed by Eduardo Valentin
parent 5b5e17a182
commit a9fae794e4
1 changed files with 25 additions and 0 deletions
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25
drivers/thermal/armada_thermal.c
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@ -54,7 +54,12 @@
#define CONTROL0_TSEN_START BIT(0)
#define CONTROL0_TSEN_RESET BIT(1)
#define CONTROL0_TSEN_ENABLE BIT(2)
#define CONTROL0_TSEN_AVG_BYPASS BIT(6)
#define CONTROL0_TSEN_OSR_SHIFT 24
#define CONTROL0_TSEN_OSR_MAX 0x3
#define CONTROL1_TSEN_AVG_SHIFT 0
#define CONTROL1_TSEN_AVG_MASK 0x7
#define CONTROL1_EXT_TSEN_SW_RESET BIT(7)
#define CONTROL1_EXT_TSEN_HW_RESETn BIT(8)
@ -194,6 +199,13 @@ static void armada_ap806_init(struct platform_device *pdev,
reg = readl_relaxed(priv->control0);
reg &= ~CONTROL0_TSEN_RESET;
reg |= CONTROL0_TSEN_START | CONTROL0_TSEN_ENABLE;
/* Sample every ~2ms */
reg |= CONTROL0_TSEN_OSR_MAX << CONTROL0_TSEN_OSR_SHIFT;
/* Enable average (2 samples by default) */
reg &= ~CONTROL0_TSEN_AVG_BYPASS;
writel(reg, priv->control0);
/* Wait the sensors to be valid or the core will warn the user */
@ -203,7 +215,20 @@ static void armada_ap806_init(struct platform_device *pdev,
static void armada_cp110_init(struct platform_device *pdev,
struct armada_thermal_priv *priv)
{
u32 reg;
armada380_init(pdev, priv);
/* Sample every ~2ms */
reg = readl_relaxed(priv->control0);
reg |= CONTROL0_TSEN_OSR_MAX << CONTROL0_TSEN_OSR_SHIFT;
writel(reg, priv->control0);
/* Average the output value over 2^1 = 2 samples */
reg = readl_relaxed(priv->control1);
reg &= ~CONTROL1_TSEN_AVG_MASK << CONTROL1_TSEN_AVG_SHIFT;
reg |= 1 << CONTROL1_TSEN_AVG_SHIFT;
writel(reg, priv->control1);
}
static bool armada_is_valid(struct armada_thermal_priv *priv)