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incubator-nuttx/drivers/i2c/i2c_driver.c

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/****************************************************************************
* drivers/i2c/i2c_driver.c
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 NuttX 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 OWNER 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 <sys/types.h>
#include <stdbool.h>
#include <stdio.h>
#include <semaphore.h>
#include <string.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/i2c/i2c_master.h>
#ifdef CONFIG_I2C_DRIVER
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Device naming ************************************************************/
#define DEVNAME_FMT "/dev/i2c%d"
#define DEVNAME_FMTLEN (8 + 3 + 1)
/****************************************************************************
* Private Types
****************************************************************************/
/* Driver state structure */
struct i2c_driver_s
{
FAR struct i2c_master_s *i2c; /* Contained I2C lower half driver */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
sem_t exclsem; /* Mutual exclusion */
int16_t crefs; /* Number of open references */
bool unlinked; /* True, driver has been unlinked */
#endif
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int i2cdrvr_open(FAR struct file *filep);
static int i2cdrvr_close(FAR struct file *filep);
static ssize_t i2cdrvr_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t i2cdrvr_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int i2cdrvr_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int i2cdrvr_unlink(FAR struct inode *inode);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations i2cdrvr_fops =
{
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
i2cdrvr_open, /* open */
i2cdrvr_close, /* close */
#else
0, /* open */
0, /* close */
#endif
i2cdrvr_read, /* read */
i2cdrvr_write, /* write */
0, /* seek */
i2cdrvr_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, 0 /* poll */
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, i2cdrvr_unlink /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: i2cdrvr_open
****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int i2cdrvr_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct i2c_driver_s *priv;
int ret;
/* Get our private data structure */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
priv = (FAR struct i2c_driver_s *)inode->i_private;
DEBUGASSERT(priv);
/* Get exclusive access to the I2C driver state structure */
ret = sem_wait(&priv->exclsem);
if (ret < 0)
{
int errcode = errno;
DEBUGASSERT(errcode < 0);
return -errcode;
}
/* Increment the count of open references on the RTC driver */
priv->crefs++;
DEBUGASSERT(priv->crefs > 0);
sem_post(&priv->exclsem);
return OK;
}
#endif
/****************************************************************************
* Name: i2cdrvr_close
****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int i2cdrvr_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct i2c_driver_s *priv;
int ret;
/* Get our private data structure */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
priv = (FAR struct i2c_driver_s *)inode->i_private;
DEBUGASSERT(priv);
/* Get exclusive access to the I2C driver state structure */
ret = sem_wait(&priv->exclsem);
if (ret < 0)
{
int errcode = errno;
DEBUGASSERT(errcode < 0);
return -errcode;
}
/* Decrement the count of open references on the RTC driver */
DEBUGASSERT(priv->crefs > 0);
priv->crefs--;
/* If the count has decremented to zero and the driver has been unlinked,
* then commit Hara-Kiri now.
*/
if (priv->crefs <= 0 && priv->unlinked)
{
sem_destroy(&priv->exclsem);
kmm_free(priv);
return OK;
}
sem_post(&priv->exclsem);
return OK;
}
#endif
/****************************************************************************
* Name: i2cdrvr_read
****************************************************************************/
static ssize_t i2cdrvr_read(FAR struct file *filep, FAR char *buffer,
size_t len)
{
return 0; /* Return EOF */
}
/****************************************************************************
* Name: i2cdrvr_write
****************************************************************************/
static ssize_t i2cdrvr_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
return len; /* Say that everything was written */
}
/****************************************************************************
* Name: i2cdrvr_ioctl
****************************************************************************/
static int i2cdrvr_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct i2c_driver_s *priv;
FAR struct i2c_transfer_s *transfer;
int ret;
i2cinfo("cmd=%d arg=%lu\n", cmd, arg);
/* Get our private data structure */
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
priv = (FAR struct i2c_driver_s *)inode->i_private;
DEBUGASSERT(priv);
/* Get exclusive access to the I2C driver state structure */
ret = sem_wait(&priv->exclsem);
if (ret < 0)
{
int errcode = errno;
DEBUGASSERT(errcode < 0);
return -errcode;
}
/* Process the IOCTL command */
switch (cmd)
{
/* Command: I2CIOC_TRANSFER
* Description: Perform an I2C transfer
* Argument: A reference to an instance of struct i2c_transfer_s.
* Dependencies: CONFIG_I2C_DRIVER
*/
case I2CIOC_TRANSFER:
{
/* Get the reference to the i2c_transfer_s structure */
transfer = (FAR struct i2c_transfer_s *)((uintptr_t)arg);
DEBUGASSERT(transfer != NULL);
/* Perform the transfer */
ret = I2C_TRANSFER(priv->i2c, transfer->msgv, transfer->msgc);
}
break;
#ifdef CONFIG_I2C_RESET
/* Command: I2CIOC_RESET
* Description: Perform an I2C bus reset in an attempt to break loose
* stuck I2C devices.
* Argument: None
* Dependencies: CONFIG_I2C_DRIVER && CONFIG_I2C_RESET
*/
case I2CIOC_RESET:
{
ret = I2C_RESET(priv->i2c);
}
break;
#endif
default:
ret = -ENOTTY;
break;
}
sem_post(&priv->exclsem);
return ret;
}
/****************************************************************************
* Name: i2cdrvr_unlink
****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int i2cdrvr_unlink(FAR struct inode *inode)
{
FAR struct i2c_driver_s *priv;
int ret;
/* Get our private data structure */
DEBUGASSERT(inode != NULL && inode->i_private != NULL);
priv = (FAR struct i2c_driver_s *)inode->i_private;
/* Get exclusive access to the I2C driver state structure */
ret = sem_wait(&priv->exclsem);
if (ret < 0)
{
int errcode = errno;
DEBUGASSERT(errcode < 0);
return -errcode;
}
/* Are there open references to the driver data structure? */
if (priv->crefs <= 0)
{
sem_destroy(&priv->exclsem);
kmm_free(priv);
return OK;
}
/* No... just mark the driver as unlinked and free the resouces when the
* last client closes their reference to the driver.
*/
priv->unlinked = true;
sem_post(&priv->exclsem);
return ret;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: i2c_register
*
* Description:
* Create and register the I2C character driver.
*
* The I2C character driver is a simple character driver that supports I2C
* transfers. The intent of this driver is to support I2C testing. It is
* not suitable for use in any real driver application.
*
* Input Parameters:
* i2c - An instance of the lower half I2C driver
* bus - The I2C bus number. This will be used as the I2C device minor
* number. The I2C character device will be registered as /dev/i2cN
* where N is the minor number
*
* Returned Value:
* OK if the driver was successfully register; A negated errno value is
* returned on any failure.
*
****************************************************************************/
int i2c_register(FAR struct i2c_master_s *i2c, int bus)
{
FAR struct i2c_driver_s *priv;
char devname[DEVNAME_FMTLEN];
int ret;
/* Sanity check */
DEBUGASSERT(i2c != NULL && (unsigned)bus < 1000);
/* Allocate a I2C character device structure */
priv = (FAR struct i2c_driver_s *)kmm_zalloc(sizeof(struct i2c_driver_s));
if (priv)
{
/* Initialize the I2C character device structure */
priv->i2c = i2c;
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
sem_init(&priv->exclsem, 0, 1);
#endif
/* Create the character device name */
snprintf(devname, DEVNAME_FMTLEN, DEVNAME_FMT, bus);
ret = register_driver(devname, &i2cdrvr_fops, 0666, priv);
if (ret < 0)
{
/* Free the device structure if we failed to create the character
* device.
*/
kmm_free(priv);
}
/* Return the result of the registration */
return OK;
}
return -ENOMEM;
}
#endif /* CONFIG_I2C_DRIVER */
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