diff --git a/drivers/iio/accel/adxl345.h b/drivers/iio/accel/adxl345.h
index 3d5c8719d..9c73474c6 100644
--- a/drivers/iio/accel/adxl345.h
+++ b/drivers/iio/accel/adxl345.h
@@ -9,37 +9,103 @@
 #define _ADXL345_H_
 
 #define ADXL345_REG_DEVID		0x00
+#define ADXL345_REG_THRESH_TAP	0x1D
 #define ADXL345_REG_OFSX		0x1E
 #define ADXL345_REG_OFSY		0x1F
 #define ADXL345_REG_OFSZ		0x20
 #define ADXL345_REG_OFS_AXIS(index)	(ADXL345_REG_OFSX + (index))
+
+/* Tap duration */
+#define ADXL345_REG_DUR		0x21
+/* Tap latency */
+#define ADXL345_REG_LATENT		0x22
+/* Tap window */
+#define ADXL345_REG_WINDOW		0x23
+/* Activity threshold */
+#define ADXL345_REG_THRESH_ACT		0x24
+/* Inactivity threshold */
+#define ADXL345_REG_THRESH_INACT	0x25
+/* Inactivity time */
+#define ADXL345_REG_TIME_INACT	0x26
+/* Axis enable control for activity and inactivity detection */
+#define ADXL345_REG_ACT_INACT_CTRL	0x27
+/* Free-fall threshold */
+#define ADXL345_REG_THRESH_FF		0x28
+/* Free-fall time */
+#define ADXL345_REG_TIME_FF		0x29
+/* Axis control for single tap or double tap */
+#define ADXL345_REG_TAP_AXIS		0x2A
+/* Source of single tap or double tap */
+#define ADXL345_REG_ACT_TAP_STATUS	0x2B
+/* Data rate and power mode control */
 #define ADXL345_REG_BW_RATE		0x2C
 #define ADXL345_REG_POWER_CTL		0x2D
+#define ADXL345_REG_INT_ENABLE		0x2E
+#define ADXL345_REG_INT_MAP		0x2F
+#define ADXL345_REG_INT_SOURCE		0x30
 #define ADXL345_REG_DATA_FORMAT		0x31
-#define ADXL345_REG_DATAX0		0x32
-#define ADXL345_REG_DATAY0		0x34
-#define ADXL345_REG_DATAZ0		0x36
-#define ADXL345_REG_DATA_AXIS(index)	\
-	(ADXL345_REG_DATAX0 + (index) * sizeof(__le16))
+#define ADXL345_REG_XYZ_BASE		0x32
+#define ADXL345_REG_DATA_AXIS(index)				\
+	(ADXL345_REG_XYZ_BASE + (index) * sizeof(__le16))
+
+#define ADXL345_REG_FIFO_CTL		0x38
+#define ADXL345_REG_FIFO_STATUS		0x39
+
+#define ADXL345_DEVID			0xE5
 
+#define ADXL345_FIFO_CTL_SAMPLES(x)	FIELD_PREP(GENMASK(4, 0), x)
+/* 0: INT1, 1: INT2 */
+#define ADXL345_FIFO_CTL_TRIGGER(x)	FIELD_PREP(BIT(5), x)
+#define ADXL345_FIFO_CTL_MODE(x)	FIELD_PREP(GENMASK(7, 6), x)
+
+#define ADXL345_INT_DATA_READY		BIT(7)
+#define ADXL345_INT_SINGLE_TAP		BIT(6)
+#define ADXL345_INT_DOUBLE_TAP		BIT(5)
+#define ADXL345_INT_ACTIVITY		BIT(4)
+#define ADXL345_INT_INACTIVITY		BIT(3)
+#define ADXL345_INT_FREE_FALL		BIT(2)
+#define ADXL345_INT_WATERMARK		BIT(1)
+#define ADXL345_INT_OVERRUN		BIT(0)
+
+#define ADXL345_S_TAP_MSK	ADXL345_INT_SINGLE_TAP
+#define ADXL345_D_TAP_MSK	ADXL345_INT_DOUBLE_TAP
+
+/*
+ * BW_RATE bits - Bandwidth and output data rate. The default value is
+ * 0x0A, which translates to a 100 Hz output data rate
+ */
 #define ADXL345_BW_RATE			GENMASK(3, 0)
+#define ADXL345_BW_LOW_POWER	BIT(4)
 #define ADXL345_BASE_RATE_NANO_HZ	97656250LL
 
-#define ADXL345_POWER_CTL_MEASURE	BIT(3)
 #define ADXL345_POWER_CTL_STANDBY	0x00
+#define ADXL345_POWER_CTL_WAKEUP	GENMASK(1, 0)
+#define ADXL345_POWER_CTL_SLEEP	BIT(2)
+#define ADXL345_POWER_CTL_MEASURE	BIT(3)
+#define ADXL345_POWER_CTL_AUTO_SLEEP	BIT(4)
+#define ADXL345_POWER_CTL_LINK	BIT(5)
 
-#define ADXL345_DATA_FORMAT_RANGE	GENMASK(1, 0)	/* Set the g range */
-#define ADXL345_DATA_FORMAT_JUSTIFY	BIT(2)	/* Left-justified (MSB) mode */
-#define ADXL345_DATA_FORMAT_FULL_RES	BIT(3)	/* Up to 13-bits resolution */
-#define ADXL345_DATA_FORMAT_SPI_3WIRE	BIT(6)	/* 3-wire SPI mode */
-#define ADXL345_DATA_FORMAT_SELF_TEST	BIT(7)	/* Enable a self test */
-
+/* Set the g range */
+#define ADXL345_DATA_FORMAT_RANGE	GENMASK(1, 0)
+/* Data is left justified */
+#define ADXL345_DATA_FORMAT_JUSTIFY	BIT(2)
+/* Up to 13-bits resolution */
+#define ADXL345_DATA_FORMAT_FULL_RES	BIT(3)
+#define ADXL345_DATA_FORMAT_SPI_3WIRE	BIT(6)
+#define ADXL345_DATA_FORMAT_SELF_TEST	BIT(7)
 #define ADXL345_DATA_FORMAT_2G		0
 #define ADXL345_DATA_FORMAT_4G		1
 #define ADXL345_DATA_FORMAT_8G		2
 #define ADXL345_DATA_FORMAT_16G		3
 
-#define ADXL345_DEVID			0xE5
+/*
+ * FIFO stores a maximum of 32 entries, which equates to a maximum of 33 entries
+ * available at any given time because an additional entry is available at the
+ * output filter of the device.
+ *
+ * (see datasheet FIFO_STATUS description on "Entries Bits")
+ */
+#define ADXL345_FIFO_SIZE  33
 
 /*
  * In full-resolution mode, scale factor is maintained at ~4 mg/LSB
