nuttx/drivers/sensors/usensor.c

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/****************************************************************************
* drivers/sensors/usensor.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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/fs/fs.h>
#include <nuttx/list.h>
#include <nuttx/kmalloc.h>
#include <nuttx/semaphore.h>
#include <nuttx/sensors/sensor.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define USENSOR_PATH "/dev/usensor"
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int usensor_open(FAR struct file *filep);
static int usensor_close(FAR struct file *filep);
static ssize_t usensor_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t usensor_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int usensor_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure describes context of usensor */
struct usensor_context_s
{
sem_t exclsem; /* Manages exclusive access to file operations */
struct list_node list; /* List of node registered */
};
/* This structure describes lowerhalf driver for an usensor registered */
struct usensor_lowerhalf_s
{
struct list_node node; /* node in all usensor list */
struct sensor_lowerhalf_s driver; /* The lowerhalf driver of user sensor */
char path[1]; /* The path of usensor character device */
};
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_usensor_fops =
{
usensor_open, /* open */
usensor_close, /* close */
usensor_read, /* read */
usensor_write, /* write */
NULL, /* seek */
usensor_ioctl, /* ioctl */
NULL, /* poll */
};
static const struct sensor_ops_s g_usensor_ops =
{
};
/****************************************************************************
* Private Functions
****************************************************************************/
static int usensor_register(FAR struct usensor_context_s *usensor,
FAR const struct sensor_reginfo_s *info)
{
FAR struct usensor_lowerhalf_s *lower;
int ret;
lower = kmm_zalloc(sizeof(*lower) + strlen(info->path));
if (!lower)
{
return -ENOMEM;
}
lower->driver.buffer_number = info->nqueue;
lower->driver.ops = &g_usensor_ops;
strcpy(lower->path, info->path);
ret = sensor_custom_register(&lower->driver, lower->path, info->esize);
if (ret < 0)
{
goto errout_with_lower;
}
ret = nxsem_wait(&usensor->exclsem);
if (ret < 0)
{
goto errout_with_register;
}
list_add_tail(&usensor->list, &lower->node);
nxsem_post(&usensor->exclsem);
return ret;
errout_with_register:
sensor_custom_unregister(&lower->driver, info->path);
errout_with_lower:
kmm_free(lower);
return ret;
}
static int usensor_unregister(FAR struct usensor_context_s *usensor,
FAR const char *path)
{
FAR struct usensor_lowerhalf_s *lower;
int ret;
ret = nxsem_wait(&usensor->exclsem);
if (ret < 0)
{
return ret;
}
list_for_every_entry(&usensor->list, lower, struct usensor_lowerhalf_s,
node)
{
if (strcmp(path, lower->path) == 0)
{
list_delete(&lower->node);
nxsem_post(&usensor->exclsem);
sensor_custom_unregister(&lower->driver, path);
kmm_free(lower);
return 0;
}
}
nxsem_post(&usensor->exclsem);
return -ENOENT;
}
static int usensor_open(FAR struct file *filep)
{
return 0;
}
static int usensor_close(FAR struct file *filep)
{
return 0;
}
static ssize_t usensor_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
return buflen;
}
static ssize_t usensor_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
return buflen;
}
static int usensor_ioctl(FAR struct file *filep, int cmd,
unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct usensor_context_s *usensor = inode->i_private;
int ret = -ENOTTY;
if (cmd == SNIOC_REGISTER)
{
FAR const struct sensor_reginfo_s *info;
info = (FAR const struct sensor_reginfo_s *)(uintptr_t)arg;
ret = usensor_register(usensor, info);
}
else if (cmd == SNIOC_UNREGISTER)
{
FAR const char *path;
path = (FAR const char *)(uintptr_t)arg;
ret = usensor_unregister(usensor, path);
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: usensor_initialize
*
* Description:
* This function registers usensor character node "/dev/usensor", so that
* application can register user sensor by this node. The node will
* manager all user sensors in this character dirver.
****************************************************************************/
int usensor_initialize(void)
{
FAR struct usensor_context_s *usensor;
int ret;
usensor = kmm_zalloc(sizeof(*usensor));
if (!usensor)
{
return -ENOMEM;
}
nxsem_init(&usensor->exclsem, 0, 1);
list_initialize(&usensor->list);
ret = register_driver(USENSOR_PATH, &g_usensor_fops, 0666, usensor);
if (ret < 0)
{
goto errout_with_sem;
}
return ret;
errout_with_sem:
nxsem_destroy(&usensor->exclsem);
kmm_free(usensor);
return ret;
}