drivers: sensor: bmm150: improve initialisation

Update driver with low level power control and OpMode
functions to better represent operations used in power
mode transition diagram Figure 2 from the datasheet.
This also prepares the driver for use of these functions
for PM actions.

Extend the soft reset at initialisation to a full POR.

Add defines for maximum POR time and start up time.

Signed-off-by: Nick Ward <[email protected]>

Author: nixward

drivers/sensor/bmm150/bmm150.c

@@ -2,6 +2,7 @@
 
 /*
  * Copyright (c) 2017 Intel Corporation
+ * Copyright (c) 2023 FTP Technologies
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -80,41 +81,22 @@ int bmm150_reg_update_byte(const struct device *dev, uint8_t reg,
 	return ret;
 }
 
-static int bmm150_set_power_mode(const struct device *dev,
-				 enum bmm150_power_modes mode,
-				 int state)
+/* Power control = 'bit' */
+static int bmm150_power_control(const struct device *dev, uint8_t bit)
 {
-	switch (mode) {
-	case BMM150_POWER_MODE_SUSPEND:
-		if (bmm150_reg_update_byte(dev,
-					   BMM150_REG_POWER,
-					   BMM150_MASK_POWER_CTL,
-					   !state) < 0) {
-			return -EIO;
-		}
-		k_busy_wait(USEC_PER_MSEC * 5U);
-
-		return 0;
-	case BMM150_POWER_MODE_SLEEP:
-		return bmm150_reg_update_byte(dev,
-					      BMM150_REG_OPMODE_ODR,
-					      BMM150_MASK_OPMODE,
-					      BMM150_MODE_SLEEP <<
-					      BMM150_SHIFT_OPMODE);
-		break;
-	case BMM150_POWER_MODE_NORMAL:
-		return bmm150_reg_update_byte(dev,
-					      BMM150_REG_OPMODE_ODR,
-					      BMM150_MASK_OPMODE,
-					      BMM150_MODE_NORMAL <<
-					      BMM150_SHIFT_OPMODE);
-		break;
-	}
-
-	return -ENOTSUP;
+	return bmm150_reg_update_byte(dev, BMM150_REG_POWER,
+				      BMM150_MASK_POWER_CTL, bit);
+}
 
+/* OpMode = 'mode' */
+static int bmm150_opmode(const struct device *dev, uint8_t mode)
+{
+	return bmm150_reg_update_byte(dev, BMM150_REG_OPMODE_ODR,
+				      BMM150_MASK_OPMODE,
+				      mode << BMM150_SHIFT_OPMODE);
 }
 
+
 static int bmm150_set_odr(const struct device *dev, uint8_t val)
 {
 	uint8_t i;
@@ -515,33 +497,63 @@ static const struct sensor_driver_api bmm150_api_funcs = {
 	.channel_get = bmm150_channel_get,
 };
 
-static int bmm150_init_chip(const struct device *dev)
+static int bmm150_full_por(const struct device *dev)
 {
-	struct bmm150_data *data = dev->data;
-	uint8_t chip_id;
-	struct bmm150_preset preset;
+	int ret;
 
-	/* Soft reset chip */
-	if (bmm150_reg_update_byte(dev, BMM150_REG_POWER, BMM150_MASK_SOFT_RESET,
-				   BMM150_SOFT_RESET) < 0) {
-		LOG_ERR("failed reset chip");
-		goto err_poweroff;
+	/* Ensure we are not in suspend mode so soft reset is not ignored */
+	ret = bmm150_power_control(dev, 1);
+	if (ret != 0) {
+		LOG_ERR("failed to ensure not in suspend mode: %d", ret);
+		return ret;
 	}
 
-	/* Sleep for 1ms after software reset */
-	k_sleep(K_MSEC(1));
+	k_sleep(BMM150_START_UP_TIME);
 
-	/* Suspend mode to sleep mode */
-	if (bmm150_set_power_mode(dev, BMM150_POWER_MODE_SUSPEND, 0)
-	    < 0) {
-		LOG_ERR("failed to bring up device from suspend mode");
-		return -EIO;
+	/* Soft reset always brings the device into sleep mode */
+	ret = bmm150_reg_update_byte(dev, BMM150_REG_POWER,
+				     BMM150_MASK_SOFT_RESET,
+				     BMM150_SOFT_RESET);
+	if (ret != 0) {
+		LOG_ERR("failed soft reset: %d", ret);
+		return ret;
 	}
 
-	/* Sleep for 3ms from suspend to sleep mode */
-	k_sleep(K_MSEC(3));
+	/*
+	 * To perform full POR (after soft reset), bring the device into suspend
+	 * mode then back into sleep mode, see datasheet section 5.6
+	 */
+	ret = bmm150_power_control(dev, 0);
+	if (ret != 0) {
+		LOG_ERR("failed to enter suspend mode: %d", ret);
+		return ret;
+	}
+
+	k_sleep(BMM150_POR_TIME);
+
+	/* Full POR - back into sleep mode */
+	ret = bmm150_power_control(dev, 1);
+	if (ret != 0) {
+		LOG_ERR("failed to go back into sleep mode: %d", ret);
+		return ret;
+	}
+
+	k_sleep(BMM150_START_UP_TIME);
 
-	/* Read chip ID */
+	return 0;
+}
+
+static int bmm150_init_chip(const struct device *dev)
+{
+	struct bmm150_data *data = dev->data;
+	struct bmm150_preset preset;
+	uint8_t chip_id;
+
+	if (bmm150_full_por(dev) != 0) {
+		goto err_poweroff;
+	}
+
+	/* Read chip ID (can only be read in sleep mode)*/
 	if (bmm150_reg_read(dev, BMM150_REG_CHIP_ID, &chip_id, 1) < 0) {
 		LOG_ERR("failed reading chip id");
 		goto err_poweroff;
@@ -574,9 +586,8 @@ static int bmm150_init_chip(const struct device *dev)
 	}
 
 	/* Set chip normal mode */
-	if (bmm150_set_power_mode(dev, BMM150_POWER_MODE_NORMAL, 1)
-	    < 0) {
-		LOG_ERR("failed to power on device");
+	if (bmm150_opmode(dev, BMM150_MODE_NORMAL) < 0) {
+		LOG_ERR("failed to enter normal mode");
 	}
 
 	/* Reads the trim registers of the sensor */
@@ -603,8 +614,8 @@ static int bmm150_init_chip(const struct device *dev)
 	return 0;
 
 err_poweroff:
-	bmm150_set_power_mode(dev, BMM150_POWER_MODE_NORMAL, 0);
-	bmm150_set_power_mode(dev, BMM150_POWER_MODE_SUSPEND, 1);
+	(void)bmm150_power_control(dev, 0); /* Suspend */
+
 	return -EIO;
 }
 

drivers/sensor/bmm150/bmm150.h

@@ -2,6 +2,7 @@
 
 /*
  * Copyright (c) 2017 Intel Corporation
+ * Copyright (c) 2023 FTP Technologies
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -116,7 +117,7 @@ extern const struct bmm150_bus_io bmm150_bus_io_i2c;
 #define BMM150_REG_INT_DRDY                0x4E
 #define BMM150_MASK_DRDY_EN                BIT(7)
 #define BMM150_SHIFT_DRDY_EN               7
-#define BMM150_DRDY_INT3              BIT(6)
+#define BMM150_DRDY_INT3                   BIT(6)
 #define BMM150_MASK_DRDY_Z_EN              BIT(5)
 #define BMM150_MASK_DRDY_Y_EN              BIT(4)
 #define BMM150_MASK_DRDY_X_EN              BIT(3)
@@ -164,12 +165,6 @@ struct bmm150_data {
 	int sample_x, sample_y, sample_z;
 };
 
-enum bmm150_power_modes {
-	BMM150_POWER_MODE_SUSPEND,
-	BMM150_POWER_MODE_SLEEP,
-	BMM150_POWER_MODE_NORMAL
-};
-
 enum bmm150_axis {
 	BMM150_AXIS_X,
 	BMM150_AXIS_Y,
@@ -196,6 +191,12 @@ enum bmm150_presets {
 	#define BMM150_DEFAULT_PRESET BMM150_HIGH_ACCURACY_PRESET
 #endif
 
+/* Power On Reset time - from OFF to Suspend (Max) */
+#define BMM150_POR_TIME K_MSEC(1)
+
+/* Start-Up Time - from suspend to sleep (Max) */
+#define BMM150_START_UP_TIME K_MSEC(3)
+
 int bmm150_reg_update_byte(const struct device *dev, uint8_t reg,
 			   uint8_t mask, uint8_t value);