KXJT9 Accelerometer driver from the Motorola Moto Z MDK

drivers/sensors/Kconfig

@@ -25,6 +25,19 @@ config BMP180
 	---help---
 		Enable driver support for the Bosch BMP180 barometer sensor.
 
+config SENSOR_KXTJ9
+	bool "Kionix KXTJ9 Accelerometer support"
+	default n
+	select I2C
+
+if SENSOR_KXTJ9
+
+config SENSOR_KXTJ9_I2C_BUS_SPEED
+	int "Kionix KXTJ9 Bus Speed in Hz"
+	default 400000
+
+endif # SENSOR_KXTJ9
+
 config LIS331DL
 	bool "ST LIS331DL device support"
 	default n

drivers/sensors/Make.defs

@@ -49,6 +49,10 @@ ifeq ($(CONFIG_AS5048B),y)
   CSRCS += as5048b.c
 endif
 
+ifeq ($(CONFIG_SENSOR_KXTJ9),y)
+  CSRCS += kxjt9.c
+endif
+
 ifeq ($(CONFIG_LIS331DL),y)
   CSRCS += lis331dl.c
 endif

drivers/sensors/kxjt9.c

+/****************************************************************************
+ * drivers/sensors/kxjt9.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * This driver derives from the Motorola Moto Z MDK:
+ *
+ *   Copyright (c) 2016 Motorola Mobility, LLC.
+ *   All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <semaphore.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/fs/fs.h>
+#include <nuttx/i2c/i2c_master.h>
+#include <nuttx/sensors/kxjt9.h>
+
+#if defined(CONFIG_I2C) && defined(CONFIG_SENSOR_KXTJ9)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Configuration ************************************************************/
+
+#ifndef CONFIG_SENSOR_KXTJ9_I2C_BUS_SPEED
+#  define CONFIG_SENSOR_KXTJ9_I2C_BUS_SPEED 400000
+#endif
+
+/* Register Definitions *****************************************************/
+
+/* Output registers */
+
+#define XOUT_L          0x06
+#define WHO_AM_I        0x0f
+#define DCST_RESP       0x0c
+
+/* Control registers */
+
+#define INT_REL         0x1a
+#define CTRL_REG1       0x1b
+#define INT_CTRL1       0x1e
+#define DATA_CTRL       0x21
+#define CTRL_REG2       0x1d
+
+/* Control register 1 bits */
+
+#define PC1_OFF         0x7f
+#define PC1_ON          (1 << 7)
+
+/* CTRL_REG1: set resolution, g-range, data ready enable */
+/* Output resolution: 8-bit valid or 12-bit valid */
+
+#define RES_8BIT        0
+#define RES_12BIT       (1 << 6)
+
+/* Data ready funtion enable bit: set during probe if using irq mode */
+
+#define DRDYE           (1 << 5)
+
+/* Output g-range: +/-2g, 4g, or 8g */
+
+#define KXTJ9_G_2G      0
+#define KXTJ9_G_4G      (1 << 3)
+#define KXTJ9_G_8G      (1 << 4)
+
+/* Interrupt control register 1 bits */
+/* Set these during probe if using irq mode */
+
+#define KXTJ9_IEL       (1 << 3)
+#define KXTJ9_IEA       (1 << 4)
+#define KXTJ9_IEN       (1 << 5)
+
+#define KXTJ9_SRST      0x80
+#define WHO_AM_I_KXCJ9  0x0a
+
+#define KXTJ9_CTRL1_CONFIG  (RES_12BIT | KXTJ9_G_2G | DRDYE)
+
+/* Misc. driver defitions ***************************************************/
+
+#define ACCEL_NUM_RETRIES   5
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/* This structure describes the state of one KXTJ9 device */
+
+struct kxjt9_dev_s
+{
+  FAR struct i2c_master_s *i2c;
+  sem_t exclsem;
+  bool enable;
+  bool power_enabled;
+  uint8_t address;
+  uint8_t shift;
+  uint8_t ctrl_reg1;
+  uint8_t data_ctrl;
+  uint8_t int_ctrl;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* I2C helpers */
+
+static int     kxtj9_reg_read(FAR struct kxjt9_dev_s *priv, uint8_t regaddr,
+                 FAR uint8_t *regval, unsigned int len);
+static int     kxtj9_reg_write(FAR struct kxjt9_dev_s *priv,
+                 uint8_t regaddr,  uint8_t regval);
+
+/* KXTJ9 helpers */
+
+static int     kxtj9_configure(FAR struct kxjt9_dev_s *priv, uint8_t odr);
+static int     kxtj9_enable(FAR struct kxjt9_dev_s *priv, bool on);
+static int     kxtj9_read_sensor_data(FAR struct kxjt9_dev_s *priv,
+                 FAR struct kxtj9_sensor_data *sensor_data);
+static void    kxtj9_soft_reset(FAR struct kxjt9_dev_s *priv);
+static void    kxtj9_set_mode_standby(FAR struct kxjt9_dev_s *priv);
+
+/* Character driver methods */
+
+static int     kxjt9_open(FAR struct file *filep);
+static int     kxjt9_close(FAR struct file *filep);
+static ssize_t kxjt9_read(FAR struct file *filep, FAR char *buffer,
+                 size_t buflen);
+static ssize_t kxjt9_write(FAR struct file *filep, FAR const char *buffer,
+                 size_t buflen);
+static int     kxjt9_ioctl(FAR struct file *filep, int cmd,
+                 unsigned long arg);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct file_operations g_fops =
+{
+  kxjt9_open,
+  kxjt9_close,
+  kxjt9_read,
+  kxjt9_write,
+  NULL,
+  kxjt9_ioctl,
+#ifndef CONFIG_DISABLE_POLL
+  NULL,
+#endif
+#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
+  NULL,
+#endif
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: kxtj9_reg_read
+ *
+ * Description:
+ *   Read from an 8-bit register.
+ *
+ ****************************************************************************/
+
+static int kxtj9_reg_read(FAR struct kxjt9_dev_s *priv, uint8_t regaddr,
+                          FAR uint8_t *regval, unsigned int len)
+{
+  struct i2c_msg_s msg[2];
+  uint8_t buf[1];
+  int retries = ACCEL_NUM_RETRIES;
+  int ret;
+
+  do
+    {
+      /* Format two messages: The first is a write containing the register
+       * address
+       */
+
+      buf[0]           = regaddr;
+
+      msg[0].frequency = CONFIG_SENSOR_KXTJ9_I2C_BUS_SPEED,
+      msg[0].addr      = priv->address;
+      msg[0].flags     = 0;
+      msg[0].buffer    = buf;
+      msg[0].length    = 1;
+
+      /* The second is a read with a restart containing the register data */
+
+      msg[1].frequency = CONFIG_SENSOR_KXTJ9_I2C_BUS_SPEED,
+      msg[1].addr      = priv->address;
+      msg[1].flags     = I2C_M_READ;
+      msg[1].buffer    = regval;
+      msg[1].length    = len;
+
+      /* Then perform the transfer. */
+
+      ret = I2C_TRANSFER(priv->i2c, msg, 2);
+    }
+  while (ret < 0 && retries-- > 0);
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: kxjt9_modifyreg8
+ *
+ * Description:
+ *   Modify an 8-bit register.
+ *
+ ****************************************************************************/
+
+static int kxtj9_reg_write(FAR struct kxjt9_dev_s *priv, uint8_t regaddr,
+                           uint8_t regval)
+{
+  struct i2c_msg_s msg;
+  uint8_t buf[2];
+  int ret;
+  int retries = ACCEL_NUM_RETRIES;
+
+  do
+    {
+      /* Setup for the transfer */
+
+      buf[0]        = regaddr;
+      buf[1]        = regval;
+
+      msg.frequency = CONFIG_SENSOR_KXTJ9_I2C_BUS_SPEED,
+      msg.addr      = priv->address;
+      msg.flags     = 0;
+      msg.buffer    = buf;
+      msg.length    = 2;
+
+      /* Then perform the transfer. */
+
+      ret = I2C_TRANSFER(priv->i2c, &msg, 1);
+    }
+  while (ret < 0 && retries-- > 0);
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: kxtj9_soft_reset
+ *
+ * Description:
+ *   Configure the KXTJ9 device.  Handler the SNIOC_CONFIGURE IOCTL command.
+ *
+ ****************************************************************************/
+
+static void kxtj9_soft_reset(FAR struct kxjt9_dev_s *priv)
+{
+  uint8_t wbuf[1];
+
+  /* Set accel into standby and known state by disabling PC1 */
+
+  wbuf[0] = KXTJ9_CTRL1_CONFIG;
+  kxtj9_reg_write(priv, CTRL_REG1, wbuf[0]);
+
+  /* Send the reset command */
+
+  kxtj9_reg_read(priv, CTRL_REG2, &wbuf[0], 1);
+
+  wbuf[0] |= KXTJ9_SRST;
+  kxtj9_reg_write(priv, CTRL_REG2, wbuf[0]);
+
+  /* Delay 10ms for the accel parts to re-initialize */
+
+  usleep(10000);
+}
+
+/****************************************************************************
+ * Name: kxtj9_set_mode_standby
+ *
+ * Description:
+ *   Configure the KXTJ9 device.  Handler the SNIOC_CONFIGURE IOCTL command.
+ *
+ ****************************************************************************/
+
+static void kxtj9_set_mode_standby(FAR struct kxjt9_dev_s *priv)
+{
+  uint8_t wbuf[1];
+
+  /* Set Accel into standby and known state by disabling PC1 */
+
+  wbuf[0] = KXTJ9_CTRL1_CONFIG;
+  kxtj9_reg_write(priv, CTRL_REG1, wbuf[0]);
+
+  /* Clear interrupts */
+
+  wbuf[0] = 0;
+  kxtj9_reg_write(priv, INT_CTRL1, wbuf[0]);
+}
+
+/****************************************************************************
+ * Name: kxtj9_configure
+ *
+ * Description:
+ *   Configure the KXTJ9 device.  Handler the SNIOC_CONFIGURE IOCTL command.
+ *
+ ****************************************************************************/
+
+static int kxtj9_configure(FAR struct kxjt9_dev_s *priv, uint8_t odr)
+{
+  uint8_t wbuf[0];
+  int ret;
+
+  do
+    {
+      ret = sem_wait(&priv->exclsem);
+    }
+  while (ret < 0 && errno == EINTR);
+
+  kxtj9_soft_reset(priv);
+  kxtj9_set_mode_standby(priv);
+
+  /* Read WHO_AM_I register, should return 0x0a */
+
+  kxtj9_reg_read(priv, WHO_AM_I, &wbuf[0], 1);
+  if (wbuf[0] != WHO_AM_I_KXCJ9)
+    {
+      snerr("ERROR: Not KXCJ9 chipset, WHO_AM_I register is 0x%2x.\n",
+            wbuf[0]);
+    }
+
+  /* Ensure that PC1 is cleared before updating control registers */
+
+  kxtj9_reg_write(priv, CTRL_REG1, 0);
+
+  /* 12Bit Res and -2G~+2G range */
+
+  priv->ctrl_reg1 = KXTJ9_CTRL1_CONFIG;
+  kxtj9_reg_write(priv, CTRL_REG1, priv->ctrl_reg1);
+
+  priv->data_ctrl = odr;
+  kxtj9_reg_write(priv, DATA_CTRL, priv->data_ctrl);
+
+  /* In irq mode, populate INT_CTRL */
+
+  priv->int_ctrl = KXTJ9_IEN | KXTJ9_IEA | KXTJ9_IEL;
+  kxtj9_reg_write(priv, INT_CTRL1, priv->int_ctrl);
+
+  sem_post(&priv->exclsem);
+  return 0;
+}
+
+/****************************************************************************
+ * Name: kxtj9_enable
+ *
+ * Description:
+ *   Enable or disable the KXTJ9 device.  Handler the SNIOC_ENABLE and
+ *   SNIOC_DISABLE IOCTL commands.
+ *
+ ****************************************************************************/
+
+static int kxtj9_enable(FAR struct kxjt9_dev_s *priv, bool on)
+{
+  uint8_t wbuf[1];
+  int ret;
+
+  do
+    {
+      ret = sem_wait(&priv->exclsem);
+    }
+  while (ret < 0 && errno == EINTR);
+
+  if (!on && priv->power_enabled)
+    {
+      priv->ctrl_reg1 &= PC1_OFF;
+      kxtj9_reg_write(priv, CTRL_REG1, priv->ctrl_reg1);
+
+      priv->power_enabled = false;
+      sninfo("KXTJ9 in disabled mode\n");
+    }
+  else if (on && !priv->power_enabled)
+    {
+      /* Turn on outputs */
+
+      priv->ctrl_reg1 |= PC1_ON;
+      kxtj9_reg_write(priv, CTRL_REG1, priv->ctrl_reg1);
+
+      /* Clear initial interrupt if in irq mode */
+
+      kxtj9_reg_read(priv, INT_REL, wbuf, 1);
+      priv->power_enabled = true;
+      sninfo("KXTJ9 in operating mode\n");
+    }
+
+  sem_post(&priv->exclsem);
+  return OK;
+}
+
+/****************************************************************************
+ * Name: kxtj9_read_sensor_data
+ *
+ * Description:
+ *   Read sensor data.  This supports the standard driver read() method.
+ *
+ ****************************************************************************/
+
+static int kxtj9_read_sensor_data(FAR struct kxjt9_dev_s *priv,
+                                  FAR struct kxtj9_sensor_data *sensor_data)
+{
+  int16_t acc_data[3];
+  uint8_t data;
+  int ret;
+
+  do
+    {
+      ret = sem_wait(&priv->exclsem);
+    }
+  while (ret < 0 && errno == EINTR);
+
+  kxtj9_reg_read(priv, XOUT_L, (uint8_t *)acc_data, 6);
+
+  /* 12 bit resolution, get rid of the lowest 4 bits */
+
+  sensor_data->x = acc_data[0] >> 4;
+  sensor_data->y = acc_data[1] >> 4;
+  sensor_data->z = acc_data[2] >> 4;
+
+  /* Read INT_REL to clear interrupt status */
+
+  kxtj9_reg_read(priv, INT_REL, &data, 1);
+  sem_post(&priv->exclsem);
+  return OK;
+}
+
+/****************************************************************************
+ * Name: kxjt9_open
+ *
+ * Description:
+ *   This method is called when the device is opened.
+ *
+ ****************************************************************************/
+
+static int kxjt9_open(FAR struct file *filep)
+{
+  return OK;
+}
+
+/****************************************************************************
+ * Name: kxjt9_close
+ *
+ * Description:
+ *   This method is called when the device is closed.
+ *
+ ****************************************************************************/
+
+static int kxjt9_close(FAR struct file *filep)
+{
+  return OK;
+}
+
+/****************************************************************************
+ * Name: kxjt9_read
+ *
+ * Description:
+ *   The standard read method.
+ *
+ ****************************************************************************/
+
+static ssize_t kxjt9_read(FAR struct file *filep, FAR char *buffer,
+                            size_t buflen)
+{
+  FAR struct inode *inode;
+  FAR struct kxjt9_dev_s *priv;
+  int ret;
+
+  /* If the provided buffer is not large enough to return a sample, then
+   * return an error.
+   */
+
+  if (buflen < sizeof(struct kxtj9_sensor_data))
+    {
+      snerr("ERROR: Bufer too small %lu < %u\n",
+            buflen, sizeof(struct kxtj9_sensor_data));
+      return (ssize_t)-EINVAL;
+    }
+
+  DEBUGASSERT(filep != NULL && filep->f_inode != NULL && buffer != NULL);
+  inode = filep->f_inode;
+
+  priv = (FAR struct kxjt9_dev_s *)inode->i_private;
+  DEBUGASSERT(priv != NULL  && priv->i2c != NULL);
+
+  /* Get the sample data */
+
+  ret = kxtj9_read_sensor_data(priv, (FAR struct kxtj9_sensor_data *)buffer);
+  if (ret < 0)
+    {
+      snerr("ERROR: kxtj9_read_sensor_data failed: %d\n", ret);
+      return (ssize_t)ret;
+    }
+
+  return sizeof(struct kxtj9_sensor_data);
+}
+
+/****************************************************************************
+ * Name: kxjt9_write
+ *
+ * Description:
+ *   A dummy write method.
+ *
+ ****************************************************************************/
+
+static ssize_t kxjt9_write(FAR struct file *filep, FAR const char *buffer,
+                             size_t buflen)
+{
+  return -ENOSYS;
+}
+
+/****************************************************************************
+ * Name: kxjt9_ioctl
+ *
+ * Description:
+ *   The standard ioctl method.
+ *
+ ****************************************************************************/
+
+static int kxjt9_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
+{
+  FAR struct inode         *inode;
+  FAR struct kxjt9_dev_s *priv;
+  int                       ret;
+
+  /* Sanity check */
+
+  DEBUGASSERT(filep != NULL);
+  inode = filep->f_inode;
+
+  DEBUGASSERT(inode != NULL);
+  priv = (FAR struct kxjt9_dev_s *)inode->i_private;
+
+  DEBUGASSERT(priv != NULL);
+
+  /* Handle ioctl commands */
+
+  switch (cmd)
+    {
+      /* Start converting. Arg: None. */
+
+      case SNIOC_ENABLE:
+        ret = kxtj9_enable(priv, true);
+        break;
+
+      /* Stop converting. Arg: None. */
+
+      case SNIOC_DISABLE:
+        ret = kxtj9_enable(priv, false);
+        break;
+
+      /* Configure the KXTJ9. Arg: enum kxtj9_odr_e value. */
+
+      case SNIOC_CONFIGURE:
+        {
+          DEBUGASSERT(arg < UINT8_MAX);
+          ret = kxtj9_configure(priv, (uint8_t)arg);
+          sninfo("SNIOC_CONFIGURE: ODR=%u ret=%d\n",
+                 (unsigned int)arg, ret);
+        }
+        break;
+
+      /* Unrecognized commands */
+
+      default:
+        snerr("ERROR: Unrecognized cmd: %d arg: %lu\n", cmd, arg);
+        ret = -ENOTTY;
+        break;
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: kxjt9_register
+ *
+ * Description:
+ *   Register the KXJT9 accelerometer device as 'devpath'.
+ *
+ * Input Parameters:
+ *   devpath - The full path to the driver to register, e.g., "/dev/accel0".
+ *   i2c     - An I2C driver instance.
+ *   addr    - The I2C address of the KXJT9 accelerometer, gyroscope or
+ *             magnetometer.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int kxjt9_register(FAR const char *devpath, FAR struct i2c_master_s *i2c,
+                   uint8_t address)
+{
+  FAR struct kxjt9_dev_s *priv;
+  int ret;
+
+  /* Sanity check */
+
+  DEBUGASSERT(devpath != NULL && i2c != NULL);
+
+  /* Initialize the device's structure */
+
+  priv = (FAR struct kxjt9_dev_s *)kmm_zalloc(sizeof(struct kxjt9_dev_s));
+  if (priv == NULL)
+    {
+      snerr("ERROR: Failed to allocate driver instance\n");
+      return -ENOMEM;
+    }
+
+  priv->i2c     = i2c;
+  priv->address = address;
+  sem_init(&priv->exclsem, 0, 1);
+
+  /* Register the character driver */
+
+  ret = register_driver(devpath, &g_fops, 0666, priv);
+  if (ret < 0)
+    {
+      snerr("ERROR: Failed to register driver: %d\n", ret);
+      kmm_free(priv);
+      return ret;
+    }
+
+  return OK;
+}
+
+#endif /* CONFIG_I2C && CONFIG_SENSOR_KXTJ9 */

include/nuttx/sensors/kxjt9.h

+/****************************************************************************
+ * include/nuttx/sensors/kxjt9.h
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * This driver derives from the Motorola Moto Z MDK:
+ *
+ *   Copyright (c) 2016 Motorola Mobility, LLC.
+ *   All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_NUTTX_SENSORS_KXJT9_H
+#define __INCLUDE_NUTTX_SENSORS_KXJT9_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <stdint.h>
+#include <nuttx/fs/ioctl.h>
+
+#if defined(CONFIG_I2C) && defined(CONFIG_SENSOR_KXTJ9)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* IOCTL Commands ***********************************************************/
+
+#define SNIOC_ENABLE      _SNIOC(0x0001) /* Arg: None */
+#define SNIOC_DISABLE     _SNIOC(0x0002) /* Arg: None */
+#define SNIOC_CONFIGURE   _SNIOC(0x0003) /* Arg: enum kxtj9_odr_e value */
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* Data control register bits */
+
+enum kxtj9_odr_e
+{
+  ODR0_781F  = 8,
+  ODR1_563F  = 9,
+  ODR3_125F  = 10,
+  ODR6_25F   = 11,
+  ODR12_5F   = 0,
+  ODR25F     = 1,
+  ODR50F     = 2,
+  ODR100F    = 3,
+  ODR200F    = 4,
+  ODR400F    = 5,
+  ODR800F    = 6
+};
+
+/* Data returned by reading from the KXTJ9 is returned in this format.
+ * In order for the read to be successful, a buffer of size >= sizeof(struct
+ * kxtj9_sensor_data) must be provided with the read.
+ */
+
+struct kxtj9_sensor_data
+{
+  uint16_t x;
+  uint16_t y;
+  uint16_t z;
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/****************************************************************************
+ * Name: kxjt9_register
+ *
+ * Description:
+ *   Register the KXJT9 accelerometer device as 'devpath'.
+ *
+ * Input Parameters:
+ *   devpath - The full path to the driver to register, e.g., "/dev/accel0".
+ *   i2c     - An I2C driver instance.
+ *   addr    - The I2C address of the KXJT9 accelerometer, gyroscope or
+ *             magnetometer.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+struct i2c_master_s;
+int kxjt9_register(FAR const char *devpath, FAR struct i2c_master_s *i2c,
+                   uint8_t address);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_I2C && CONFIG_SENSOR_KXTJ9 */
+#endif /* __INCLUDE_NUTTX_SENSORS_KXJT9_H */