[PATCH v11 5/9] drivers: thermal: tsens: Fix bug in sensor enable for msm8960

[Ansuel Smith <ansuelsmth@gmail.com>]

Device based on tsens VER_0 contains a hardware bug that results in some
problem with sensor enablement. Sensor id 6-11 can't be enabled
selectively and all of them must be enabled in one step.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
 drivers/thermal/qcom/tsens-8960.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/qcom/tsens-8960.c b/drivers/thermal/qcom/tsens-8960.c
index 86585f439985..bdc64d4188bf 100644
--- a/drivers/thermal/qcom/tsens-8960.c
+++ b/drivers/thermal/qcom/tsens-8960.c
@@ -27,9 +27,9 @@
 #define EN			BIT(0)
 #define SW_RST			BIT(1)
 #define SENSOR0_EN		BIT(3)
+#define MEASURE_PERIOD		BIT(18)
 #define SLP_CLK_ENA		BIT(26)
 #define SLP_CLK_ENA_8660	BIT(24)
-#define MEASURE_PERIOD		1
 #define SENSOR0_SHIFT		3
 
 /* INT_STATUS_ADDR bitmasks */
@@ -126,17 +126,35 @@ static int resume_8960(struct tsens_priv *priv)
 static int enable_8960(struct tsens_priv *priv, int id)
 {
 	int ret;
-	u32 reg, mask;
+	u32 reg, mask = BIT(id);
 
 	ret = regmap_read(priv->tm_map, CNTL_ADDR, &reg);
 	if (ret)
 		return ret;
 
-	mask = BIT(id + SENSOR0_SHIFT);
+	/* HARDWARE BUG:
+	 * On platform with more than 6 sensors, all the remaining
+	 * sensors needs to be enabled all togheder or underfined
+	 * results are expected. (Sensor 6-7 disabled, Sensor 3
+	 * disabled...) In the original driver, all the sensors
+	 * are enabled in one step hence this bug is not triggered.
+	 */
+	if (id > 5) {
+		mask = GENMASK(10, 6);
+
+		/* Sensors already enabled. Skip. */
+		if ((reg & mask) == mask)
+			return 0;
+	}
+
+	mask <<= SENSOR0_SHIFT;
+
 	ret = regmap_write(priv->tm_map, CNTL_ADDR, reg | SW_RST);
 	if (ret)
 		return ret;
 
+	reg |= MEASURE_PERIOD;
+
 	if (priv->num_sensors > 1)
 		reg |= mask | SLP_CLK_ENA | EN;
 	else
-- 
2.30.2