From 5274aa5dc21f15613bac9ab04e84d410cea7f4cd Mon Sep 17 00:00:00 2001
From: Efrain Calderon <efrain.calderon@aquarobur.com>
Date: Tue, 27 Jul 2021 16:51:41 +0200
Subject: [PATCH] drivers: bme280: fetch data after measurement is done

After powering-on the sensor, and before every measurement, it loads
the NMV. We must wait until this process is completed otherwise
we will read weird values.
Since it was observed that the time may be a bit long after a cold
start, it is more convinient to just wait until the sensor iready,
without a timout.

Signed-off-by: Efrain Calderon <efrain.calderon@aquarobur.com>
---
 drivers/sensor/bme280/bme280.c | 34 ++++++++++++++++++++++++++--------
 drivers/sensor/bme280/bme280.h |  4 +++-
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/sensor/bme280/bme280.c b/drivers/sensor/bme280/bme280.c
index c1372af2c29..0079997c250 100644
--- a/drivers/sensor/bme280/bme280.c
+++ b/drivers/sensor/bme280/bme280.c
@@ -170,6 +170,23 @@ static void bme280_compensate_humidity(struct bme280_data *data,
 	data->comp_humidity = (uint32_t)(h >> 12);
 }
 
+static int bme280_wait_until_ready(const struct device *dev)
+{
+	uint8_t status = 0;
+	int ret;
+
+	/* Wait for NVM to copy and and measurement to be completed */
+	do {
+		k_sleep(K_MSEC(3));
+		ret = bme280_reg_read(dev, BME280_REG_STATUS, &status, 1);
+		if (ret < 0) {
+			return ret;
+		}
+	} while (status & (BME280_STATUS_MEASURING | BME280_STATUS_IM_UPDATE));
+
+	return 0;
+}
+
 static int bme280_sample_fetch(const struct device *dev,
 			       enum sensor_channel chan)
 {
@@ -192,16 +209,13 @@ static int bme280_sample_fetch(const struct device *dev,
 	if (ret < 0) {
 		return ret;
 	}
-
-	do {
-		k_sleep(K_MSEC(3));
-		ret = bme280_reg_read(dev, BME280_REG_STATUS, buf, 1);
-		if (ret < 0) {
-			return ret;
-		}
-	} while (buf[0] & 0x08);
 #endif
 
+	ret = bme280_wait_until_ready(dev);
+	if (ret < 0) {
+		return ret;
+	}
+
 	if (data->chip_id == BME280_CHIP_ID) {
 		size = 8;
 	}
@@ -356,6 +370,10 @@ static int bme280_chip_init(const struct device *dev)
 	err = bme280_reg_write(dev, BME280_REG_RESET, BME280_CMD_SOFT_RESET);
 	if (err < 0) {
 		LOG_DBG("Soft-reset failed: %d", err);
+	}
+
+	err = bme280_wait_until_ready(dev);
+	if (err < 0) {
 		return err;
 	}
 
diff --git a/drivers/sensor/bme280/bme280.h b/drivers/sensor/bme280/bme280.h
index 9aa6e175376..e141d04143d 100644
--- a/drivers/sensor/bme280/bme280.h
+++ b/drivers/sensor/bme280/bme280.h
@@ -74,6 +74,8 @@ extern const struct bme280_bus_io bme280_bus_io_i2c;
 #define BME280_MODE_NORMAL              0x03
 #define BME280_SPI_3W_DISABLE           0x00
 #define BME280_CMD_SOFT_RESET           0xB6
+#define BME280_STATUS_MEASURING         0x08
+#define BME280_STATUS_IM_UPDATE         0x01
 
 #if defined CONFIG_BME280_MODE_NORMAL
 #define BME280_MODE BME280_MODE_NORMAL
@@ -155,7 +157,7 @@ extern const struct bme280_bus_io bme280_bus_io_i2c;
 					 BME280_SPI_3W_DISABLE)
 
 
-#define BME280_CTRL_MEAS_OFF_VAL		(BME280_PRESS_OVER | \
+#define BME280_CTRL_MEAS_OFF_VAL	(BME280_PRESS_OVER | \
 					 BME280_TEMP_OVER |  \
 					 BME280_MODE_SLEEP)