nuttx/drivers/power/battery_gauge.c

/****************************************************************************
 * drivers/power/battery_gauge_gauge.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/* Upper-half, character driver for battery fuel gauge. */

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdbool.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/fs/fs.h>
#include <nuttx/power/battery_gauge.h>
#include <nuttx/power/battery_ioctl.h>

/* This driver requires:
 *
 * CONFIG_BATTERY_GAUGE - Upper half battery driver support
 */

#if defined(CONFIG_BATTERY_GAUGE)

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/* Character driver methods */

static int     bat_gauge_open(FAR struct file *filep);
static int     bat_gauge_close(FAR struct file *filep);
static ssize_t bat_gauge_read(FAR struct file *filep,
                              FAR char *buffer,
                              size_t buflen);
static ssize_t bat_gauge_write(FAR struct file *filep,
                               FAR const char *buffer,
                               size_t buflen);
static int     bat_gauge_ioctl(FAR struct file *filep, int cmd,
                               unsigned long arg);

/****************************************************************************
 * Private Data
 ****************************************************************************/

static const struct file_operations g_batteryops =
{
  bat_gauge_open,
  bat_gauge_close,
  bat_gauge_read,
  bat_gauge_write,
  NULL,
  bat_gauge_ioctl,
  NULL
};

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: bat_gauge_open
 *
 * Description:
 *   This function is called whenever the battery device is opened.
 *
 ****************************************************************************/

static int bat_gauge_open(FAR struct file *filep)
{
  return OK;
}

/****************************************************************************
 * Name: bat_gauge_close
 *
 * Description:
 *   This routine is called when the battery device is closed.
 *
 ****************************************************************************/

static int bat_gauge_close(FAR struct file *filep)
{
  return OK;
}

/****************************************************************************
 * Name: bat_gauge_read
 ****************************************************************************/

static ssize_t bat_gauge_read(FAR struct file *filep, FAR char *buffer,
                              size_t buflen)
{
  /* Return nothing read */

  return 0;
}

/****************************************************************************
 * Name: bat_gauge_write
 ****************************************************************************/

static ssize_t bat_gauge_write(FAR struct file *filep,
                               FAR const char *buffer,
                               size_t buflen)
{
  /* Return nothing written */

  return 0;
}

/****************************************************************************
 * Name: bat_gauge_ioctl
 ****************************************************************************/

static int bat_gauge_ioctl(FAR struct file *filep,
                           int cmd,
                           unsigned long arg)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct battery_gauge_dev_s *dev  = inode->i_private;
  int ret;

  /* Enforce mutually exclusive access to the battery driver */

  ret = nxsem_wait(&dev->batsem);
  if (ret < 0)
    {
      return ret; /* Probably -EINTR */
    }

  /* Procss the IOCTL command */

  ret = -EINVAL;  /* Assume a bad argument */
  switch (cmd)
    {
      case BATIOC_STATE:
        {
          FAR int *ptr = (FAR int *)((uintptr_t)arg);
          if (ptr)
            {
              ret = dev->ops->state(dev, ptr);
            }
        }
        break;

      case BATIOC_ONLINE:
        {
          FAR bool *ptr = (FAR bool *)((uintptr_t)arg);
          if (ptr)
            {
              ret = dev->ops->online(dev, ptr);
            }
        }
        break;

      case BATIOC_VOLTAGE:
        {
          FAR b16_t *ptr = (FAR b16_t *)((uintptr_t)arg);
          if (ptr)
            {
              ret = dev->ops->voltage(dev, ptr);
            }
        }
        break;

      case BATIOC_CAPACITY:
        {
          FAR b16_t *ptr = (FAR b16_t *)((uintptr_t)arg);
          if (ptr)
            {
              ret = dev->ops->capacity(dev, ptr);
            }
        }
        break;

      default:
        _err("ERROR: Unrecognized cmd: %d\n", cmd);
        ret = -ENOTTY;
        break;
    }

  nxsem_post(&dev->batsem);
  return ret;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: battery_gauge_register
 *
 * Description:
 *   Register a lower half battery driver with the common, upper-half
 *   battery driver.
 *
 * Input Parameters:
 *   devpath - The location in the pseudo-filesystem to create the driver.
 *     Recommended standard is "/dev/bat0", "/dev/bat1", etc.
 *   dev - An instance of the battery state structure .
 *
 * Returned Value:
 *    Zero on success or a negated errno value on failure.
 *
 ****************************************************************************/

int battery_gauge_register(FAR const char *devpath,
                           FAR struct battery_gauge_dev_s *dev)
{
  int ret;

  /* Initialize the semaphore */

  nxsem_init(&dev->batsem, 0, 1);

  /* Register the character driver */

  ret = register_driver(devpath, &g_batteryops, 0555, dev);
  if (ret < 0)
    {
      _err("ERROR: Failed to register driver: %d\n", ret);
    }

  return ret;
}
#endif /* CONFIG_BATTERY_GAUGE */