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nuttx/drivers/watchdog.c

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/****************************************************************************
* drivers/watchdog.c
*
* Copyright (C) 2012 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 <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <semaphore.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/fs/fs.h>
#include <nuttx/irq.h>
#include <nuttx/kmalloc.h>
#include <nuttx/watchdog.h>
#ifdef CONFIG_WATCHDOG
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Debug ********************************************************************/
/* Non-standard debug that may be enabled just for testing the watchdog driver */
#ifdef CONFIG_DEBUG_WATCHDOG
# define wddbg dbg
# define wdvdbg vdbg
# define wdlldbg lldbg
# define wdllvdbg llvdbg
#else
# define wddbg(x...)
# define wdvdbg(x...)
# define wdlldbg(x...)
# define wdllvdbg(x...)
#endif
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/* This structure describes the state of the upper half driver */
struct watchdog_upperhalf_s
{
uint8_t crefs; /* The number of times the device has been opened */
sem_t exclsem; /* Supports mutual exclusion */
FAR char *path; /* Registration path */
/* The contained lower-half driver */
FAR struct watchdog_lowerhalf_s *lower;
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int wdog_open(FAR struct file *filep);
static int wdog_close(FAR struct file *filep);
static ssize_t wdog_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t wdog_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int wdog_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_wdogops =
{
wdog_open, /* open */
wdog_close, /* close */
wdog_read, /* read */
wdog_write, /* write */
0, /* seek */
wdog_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, 0 /* poll */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/************************************************************************************
* Name: wdog_open
*
* Description:
* This function is called whenever the watchdog timer device is opened.
*
************************************************************************************/
static int wdog_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct watchdog_upperhalf_s *upper = inode->i_private;
uint8_t tmp;
int ret;
wdvdbg("crefs: %d\n", upper->crefs);
/* Get exclusive access to the device structures */
ret = sem_wait(&upper->exclsem);
if (ret < 0)
{
ret = -get_errno();
goto errout;
}
/* Increment the count of references to the device. If this the first
* time that the driver has been opened for this device, then initialize
* the device.
*/
tmp = upper->crefs + 1;
if (tmp == 0)
{
/* More than 255 opens; uint8_t overflows to zero */
ret = -EMFILE;
goto errout_with_sem;
}
/* Save the new open count */
upper->crefs = tmp;
ret = OK;
errout_with_sem:
sem_post(&upper->exclsem);
errout:
return ret;
}
/************************************************************************************
* Name: wdog_close
*
* Description:
* This function is called when the watchdog timer device is closed.
*
************************************************************************************/
static int wdog_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct watchdog_upperhalf_s *upper = inode->i_private;
int ret;
wdvdbg("crefs: %d\n", upper->crefs);
/* Get exclusive access to the device structures */
ret = sem_wait(&upper->exclsem);
if (ret < 0)
{
ret = -get_errno();
goto errout;
}
/* Decrement the references to the driver. If the reference count will
* decrement to 0, then uninitialize the driver.
*/
if (upper->crefs > 0)
{
upper->crefs--;
}
sem_post(&upper->exclsem);
ret = OK;
errout:
return ret;
}
/************************************************************************************
* Name: wdog_read
*
* Description:
* A dummy read method. This is provided only to satisfy the VFS layer.
*
************************************************************************************/
static ssize_t wdog_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
{
/* Return zero -- usually meaning end-of-file */
return 0;
}
/************************************************************************************
* Name: wdog_write
*
* Description:
* A dummy write method. This is provided only to satisfy the VFS layer.
*
************************************************************************************/
static ssize_t wdog_write(FAR struct file *filep, FAR const char *buffer, size_t buflen)
{
return 0;
}
/************************************************************************************
* Name: wdog_ioctl
*
* Description:
* The standard ioctl method. This is where ALL of the watchdog timer work is
* done.
*
************************************************************************************/
static int wdog_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct watchdog_upperhalf_s *upper = inode->i_private;
FAR struct watchdog_lowerhalf_s *lower = upper->lower;
int ret;
wdvdbg("cmd: %d arg: %ld\n", cmd, arg);
DEBUGASSERT(upper && lower);
/* Get exclusive access to the device structures */
ret = sem_wait(&upper->exclsem);
if (ret < 0)
{
return ret;
}
/* Handle built-in ioctl commands */
switch (cmd)
{
/* cmd: WDIOC_START
* Description: Start the watchdog timer
* Argument: Ignored
*/
case WDIOC_START:
{
/* Start the watchdog timer, resetting the time to the current timeout */
DEBUGASSERT(lower->ops->start); /* Required */
ret = lower->ops->start(lower);
}
break;
/* cmd: WDIOC_STOP
* Description: Stop the watchdog timer
* Argument: Ignored
*/
case WDIOC_STOP:
{
/* Stop the watchdog timer */
DEBUGASSERT(lower->ops->stop); /* Required */
ret = lower->ops->stop(lower);
}
break;
/* cmd: WDIOC_GETSTATUS
* Description: Get the status of the watchdog timer.
* Argument: A writeable pointer to struct watchdog_status_s.
*/
case WDIOC_GETSTATUS:
{
FAR struct watchdog_status_s *status;
/* Get the current watchdog timer status */
if (lower->ops->getstatus) /* Optional */
{
status = (FAR struct watchdog_status_s *)((uintptr_t)arg);
if (status)
{
ret = lower->ops->getstatus(lower, status);
}
else
{
ret = -EINVAL;
}
}
else
{
ret = -ENOSYS;
}
}
break;
/* cmd: WDIOC_SETTIMEOUT
* Description: Reset the watchdog timeout to this value
* Argument: A 32-bit timeout value in milliseconds.
*/
case WDIOC_SETTIMEOUT:
{
/* Set a new timeout value (and reset the watchdog timer) */
if (lower->ops->settimeout) /* Optional */
{
ret = lower->ops->settimeout(lower, (uint32_t)arg);
}
else
{
ret = -ENOSYS;
}
}
break;
/* cmd: WDIOC_CAPTURE
* Description: Do not reset. Instead, called this handler.
* Argument: A pointer to struct watchdog_capture_s.
*/
case WDIOC_CAPTURE:
{
FAR struct watchdog_capture_s *capture;
/* Don't reset on watchdog timer timeout; instead, call this user
* provider timeout handler. NOTE: Providing handler==NULL will
* restore the reset behavior.
*/
if (lower->ops->capture) /* Optional */
{
capture = (FAR struct watchdog_capture_s *)((uintptr_t)arg);
if (capture)
{
capture->oldhandler =
lower->ops->capture(lower, capture->newhandler);
ret = OK;
}
else
{
ret = -EINVAL;
}
}
else
{
ret = -ENOSYS;
}
}
break;
/* cmd: WDIOC_KEEPALIVE
* Description: Reset the watchdog timer ("ping", "pet the dog")
* Argument: Argument: Ignored
*/
case WDIOC_KEEPALIVE:
{
/* Reset the watchdog timer to the current timeout value, prevent any
* imminent watchdog timeouts. This is sometimes referred as
* "pinging" the watchdog timer or "petting the dog".
*/
if (lower->ops->keepalive) /* Optional */
{
ret = lower->ops->keepalive(lower);
}
else
{
ret = -ENOSYS;
}
}
break;
/* Any unrecognized IOCTL commands might be platform-specific ioctl commands */
default:
{
wdvdbg("Forwarding unrecognized cmd: %d arg: %ld\n", cmd, arg);
/* An ioctl commands that are not recognized by the "upper-half"
* driver are forwarded to the lower half driver through this
* method.
*/
if (lower->ops->ioctl) /* Optional */
{
ret = lower->ops->ioctl(lower, cmd, arg);
}
else
{
ret = -ENOSYS;
}
}
break;
}
sem_post(&upper->exclsem);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: watchdog_register
*
* Description:
* This function binds an instance of a "lower half" watchdog driver with the
* "upper half" watchdog device and registers that device so that can be used
* by application code.
*
* When this function is called, the "lower half" driver should be in the
* disabled state (as if the stop() method had already been called).
*
* Input parameters:
* dev path - The full path to the driver to be registers in the NuttX
* pseudo-filesystem. The recommended convention is to name all watchdog
* drivers as "/dev/watchdog0", "/dev/watchdog1", etc. where the driver
* path differs only in the "minor" number at the end of the device name.
* lower - A pointer to an instance of lower half watchdog driver. This
* instance is bound to the watchdog driver and must persists as long as
* the driver persists.
*
* Returned Value:
* On success, a non-NULL handle is returned to the caller. In the event
* of any failure, a NULL value is returned.
*
****************************************************************************/
FAR void *watchdog_register(FAR const char *path,
FAR struct watchdog_lowerhalf_s *lower)
{
FAR struct watchdog_upperhalf_s *upper;
int ret;
DEBUGASSERT(path && lower);
wdvdbg("Entry: path=%s\n", path);
/* Allocate the upper-half data structure */
upper = (FAR struct watchdog_upperhalf_s *)
kzalloc(sizeof(struct watchdog_upperhalf_s));
if (!upper)
{
wddbg("Upper half allocation failed\n");
goto errout;
}
/* Initialize the watchdog timer device structure (it was already zeroed
* by kzalloc()).
*/
sem_init(&upper->exclsem, 0, 1);
upper->lower = lower;
/* Copy the registration path */
upper->path = strdup(path);
if (!upper->path)
{
wddbg("Path allocation failed\n");
goto errout_with_upper;
}
/* Register the watchdog timer device */
ret = register_driver(path, &g_wdogops, 0666, upper);
if (ret < 0)
{
wddbg("register_driver failed: %d\n", ret);
goto errout_with_path;
}
return (FAR void *)upper;
errout_with_path:
kmm_free(upper->path);
errout_with_upper:
sem_destroy(&upper->exclsem);
kmm_free(upper);
errout:
return NULL;
}
/****************************************************************************
* Name: watchdog_unregister
*
* Description:
* This function can be called to disable and unregister the watchdog
* device driver.
*
* Input parameters:
* handle - This is the handle that was returned by watchdog_register()
*
* Returned Value:
* None
*
****************************************************************************/
void watchdog_unregister(FAR void *handle)
{
FAR struct watchdog_upperhalf_s *upper;
FAR struct watchdog_lowerhalf_s *lower;
/* Recover the pointer to the upper-half driver state */
upper = (FAR struct watchdog_upperhalf_s *)handle;
lower = upper->lower;
DEBUGASSERT(upper && lower);
wdvdbg("Unregistering: %s\n", upper->path);
/* Disable the watchdog timer */
DEBUGASSERT(lower->ops->stop); /* Required */
(void)lower->ops->stop(lower);
/* Unregister the watchdog timer device */
(void)unregister_driver(upper->path);
/* Then free all of the driver resources */
kmm_free(upper->path);
sem_destroy(&upper->exclsem);
kmm_free(upper);
}
#endif /* CONFIG_WATCHDOG */
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