drivers: sensor: mpu6050: support for choosing sample rate divider

drivers/sensor/tdk/mpu6050/mpu6050.c

@@ -177,10 +177,77 @@ int mpu6050_init(const struct device *dev)
 		return -EINVAL;
 	}
 
-	/* wake up chip */
-	if (i2c_reg_update_byte_dt(&cfg->i2c, MPU6050_REG_PWR_MGMT1,
-				   MPU6050_SLEEP_EN, 0) < 0) {
-		LOG_ERR("Failed to wake up chip.");
+	/* Reset sequence is added to ensure all registers are reset to their
+	 * default values, and also to enable easier addition of SPI support in
+	 * future.
+	 */
+	/* When using SPI interface, user should use DEVICE_RESET as well as
+	 * SIGNAL_PATH_RESET to ensure th ereest is performed properly.
+	 * The sequence used should be:
+	 * 1. Set DEVICE_RESET = 1 (reg PWR_MGMT_1)
+	 * 2. Wait 100ms
+	 * 3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (reg SIGNAL_PATH_RESET)
+	 * 4. Wait 100ms
+	 * (RM-MPU-6000A-00 rev 4.2 page 41 of 46)
+	 */
+	if (i2c_reg_write_byte_dt(&cfg->i2c, MPU6050_REG_PWR_MGMT1, MPU6050_DEVICE_RESET) < 0) {
+		LOG_ERR("Device reset failed.");
+		return -EIO;
+	}
+
+	k_sleep(K_MSEC(100));
+
+	/* check content of Power Management 1 register. */
+	uint8_t tmp;
+
+	if ((i2c_reg_read_byte_dt(&cfg->i2c, MPU6050_REG_PWR_MGMT1, &tmp) < 0)) {
+		LOG_ERR("Device reset request failed.");
+		return -EIO;
+	}
+
+	if (tmp != MPU6050_PWR_MGMT1_RST_VAL) {
+		LOG_ERR("Device reset failed.");
+		return -EINVAL;
+	}
+
+	/* select clock source.
+	 * While gyros are active, selecting the gyros as the clock source provides
+	 * for a more accurate clock source.
+	 * (Document Number: PS-MPU-6000A-00 Page 30 of 52)
+	 */
+	if (i2c_reg_write_byte_dt(&cfg->i2c, MPU6050_REG_PWR_MGMT1, 0x01) < 0) {
+		LOG_ERR("Clock select failed.");
+		return -EIO;
+	}
+
+	/* signal paths reset. */
+	if (i2c_reg_update_byte_dt(&cfg->i2c, MPU6050_REG_SIGNAL_PATH_RESET,
+				   (MPU6050_GYRO_RESET | MPU6050_ACCEL_RESET | MPU6050_TEMP_RESET),
+				   0x07) < 0) {
+		LOG_ERR("Signal path reset failed.");
+		return -EIO;
+	}
+
+	/* reset signal paths of all sensors and clear sensor registers. */
+	if (i2c_reg_update_byte_dt(&cfg->i2c, MPU6050_REG_USER_CTRL, MPU6050_SIG_COND_RESET, 1) <
+	    0) {
+		LOG_ERR("Signal path reset failed.");
+		return -EIO;
+	}
+
+	k_sleep(K_MSEC(100));
+
+	if (cfg->smplrt_div > 255 || cfg->smplrt_div < 4) {
+		LOG_ERR("Not supported sample rate divider");
+		return -ENOTSUP;
+	}
+
+	/* Sample Rate = Gyroscope Output Rate / (1 + smplrt_div)
+	 * (RM-MPU-6000A-00 rev 4.2 page 12 of 46)
+	 */
+	if (i2c_reg_write_byte_dt(&cfg->i2c, MPU6050_REG_SAMPLE_RATE_DIVIDER, cfg->smplrt_div) <
+	    0) {
+		LOG_ERR("Sample rate divider configuration failed.");
 		return -EIO;
 	}
 
@@ -233,21 +300,26 @@ int mpu6050_init(const struct device *dev)
 	}
 #endif
 
+	/* wake up chip */
+	if (i2c_reg_update_byte_dt(&cfg->i2c, MPU6050_REG_PWR_MGMT1, MPU6050_SLEEP_EN, 0) < 0) {
+		LOG_ERR("Failed to wake up chip.");
+		return -EIO;
+	}
+
 	return 0;
 }
 
-#define MPU6050_DEFINE(inst)									\
-	static struct mpu6050_data mpu6050_data_##inst;						\
-												\
-	static const struct mpu6050_config mpu6050_config_##inst = {				\
-		.i2c = I2C_DT_SPEC_INST_GET(inst),						\
-		IF_ENABLED(CONFIG_MPU6050_TRIGGER,						\
-			   (.int_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, int_gpios, { 0 }),))	\
-	};											\
-												\
-	SENSOR_DEVICE_DT_INST_DEFINE(inst, mpu6050_init, NULL,					\
-			      &mpu6050_data_##inst, &mpu6050_config_##inst,			\
-			      POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY,				\
-			      &mpu6050_driver_api);						\
+#define MPU6050_DEFINE(inst)                                                                       \
+	static struct mpu6050_data mpu6050_data_##inst;                                            \
+                                                                                                   \
+	static const struct mpu6050_config mpu6050_config_##inst = {                               \
+		.i2c = I2C_DT_SPEC_INST_GET(inst),                                                 \
+		.int_gpio = GPIO_DT_SPEC_INST_GET(inst, int_gpios),                                \
+		.smplrt_div = DT_INST_PROP(inst, smplrt_div),                                      \
+	};                                                                                         \
+                                                                                                   \
+	SENSOR_DEVICE_DT_INST_DEFINE(inst, mpu6050_init, NULL, &mpu6050_data_##inst,               \
+				     &mpu6050_config_##inst, POST_KERNEL,                          \
+				     CONFIG_SENSOR_INIT_PRIORITY, &mpu6050_driver_api);
 
 DT_INST_FOREACH_STATUS_OKAY(MPU6050_DEFINE)

drivers/sensor/tdk/mpu6050/mpu6050.h

@@ -20,6 +20,9 @@
 #define MPU9250_CHIP_ID			0x71
 #define MPU6880_CHIP_ID			0x19
 
+/* Sample Rate Divider Register */
+#define MPU6050_REG_SAMPLE_RATE_DIVIDER 0x19
+
 #define MPU6050_REG_GYRO_CFG		0x1B
 #define MPU6050_GYRO_FS_SHIFT		3
 
@@ -31,8 +34,20 @@
 
 #define MPU6050_REG_DATA_START		0x3B
 
-#define MPU6050_REG_PWR_MGMT1		0x6B
-#define MPU6050_SLEEP_EN		BIT(6)
+/* Signal Path Reset Register */
+#define MPU6050_REG_SIGNAL_PATH_RESET 0x68
+#define MPU6050_TEMP_RESET            BIT(0)
+#define MPU6050_ACCEL_RESET           BIT(1)
+#define MPU6050_GYRO_RESET            BIT(2)
+
+/* User Control Register */
+#define MPU6050_REG_USER_CTRL  0x6A
+#define MPU6050_SIG_COND_RESET BIT(0)
+
+#define MPU6050_REG_PWR_MGMT1     0x6B
+#define MPU6050_SLEEP_EN          BIT(6)
+#define MPU6050_DEVICE_RESET      BIT(7)
+#define MPU6050_PWR_MGMT1_RST_VAL 0x40
 
 /* measured in degrees/sec x10 to avoid floating point */
 static const uint16_t mpu6050_gyro_sensitivity_x10[] = {
@@ -80,9 +95,8 @@ struct mpu6050_data {
 
 struct mpu6050_config {
 	struct i2c_dt_spec i2c;
-#ifdef CONFIG_MPU6050_TRIGGER
 	struct gpio_dt_spec int_gpio;
-#endif /* CONFIG_MPU6050_TRIGGER */
+	int smplrt_div;
 };
 
 #ifdef CONFIG_MPU6050_TRIGGER

dts/bindings/sensor/invensense,mpu6050.yaml

@@ -16,3 +16,14 @@ properties:
       The INT signal default configuration is active-high.  The
       property value should ensure the flags properly describe the
       signal that is presented to the driver.
+
+  smplrt-div:
+    type: int
+    default: 7
+    description: |
+      Sensor Data Sample Rate Divider.
+      Sensor data Sample Rate = 8000Hz / (1 + Sample Rate Divider).
+      While using I2C minimal Data Sample Rate Divider is 4, which results in
+      1600Hz Sensor Data Sample Rate. Sample Rates higher than this are not
+      recommended while using I2C.
+      Valid range: 4 - 255