[PATCH v2 05/23] thermal: armada: average over samples to avoid glitches

Miquel Raynal
2018-06-25T15:12:21Z

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>
---
drivers/thermal/armada_thermal.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
index 9291ea3ad2f7..1f9706d96a0d 100644
--- a/drivers/thermal/armada_thermal.c
+++ b/drivers/thermal/armada_thermal.c
@@ -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)
--
2.14.1