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incubator-nuttx/drivers/timers/timer.c

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/****************************************************************************
* drivers/timers/timer.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 <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/lib/lib.h>
#include <nuttx/signal.h>
#include <nuttx/fs/fs.h>
#include <nuttx/mutex.h>
#include <nuttx/timers/timer.h>
#ifdef CONFIG_TIMER
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/* This structure describes the state of the upper half driver */
struct timer_upperhalf_s
{
mutex_t lock; /* Supports mutual exclusion */
uint8_t crefs; /* The number of times the device has been opened */
FAR char *path; /* Registration path */
/* The contained signal info */
struct timer_notify_s notify;
struct sigwork_s work;
/* The contained lower-half driver */
FAR struct timer_lowerhalf_s *lower;
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static bool timer_notifier(FAR uint32_t *next_interval_us, FAR void *arg);
static int timer_open(FAR struct file *filep);
static int timer_close(FAR struct file *filep);
static ssize_t timer_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t timer_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int timer_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_timerops =
{
timer_open, /* open */
timer_close, /* close */
timer_read, /* read */
timer_write, /* write */
NULL, /* seek */
timer_ioctl, /* ioctl */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: timer_notifier
*
* Description:
* Notify the application via a signal when the timer interrupt occurs
*
* REVISIT: This function prototype is insufficient to support signaling
*
****************************************************************************/
static bool timer_notifier(FAR uint32_t *next_interval_us, FAR void *arg)
{
FAR struct timer_upperhalf_s *upper = (FAR struct timer_upperhalf_s *)arg;
FAR struct timer_notify_s *notify = &upper->notify;
DEBUGASSERT(upper != NULL);
/* Signal the waiter.. if there is one */
nxsig_notification(notify->pid, &notify->event, SI_QUEUE, &upper->work);
return notify->periodic;
}
/****************************************************************************
* Name: timer_open
*
* Description:
* This function is called whenever the timer device is opened.
*
****************************************************************************/
static int timer_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct timer_upperhalf_s *upper = inode->i_private;
uint8_t tmp;
int ret;
tmrinfo("crefs: %d\n", upper->crefs);
/* Get exclusive access to the device structures */
ret = nxmutex_lock(&upper->lock);
if (ret < 0)
{
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_lock;
}
/* Save the new open count */
upper->crefs = tmp;
ret = OK;
errout_with_lock:
nxmutex_unlock(&upper->lock);
errout:
return ret;
}
/****************************************************************************
* Name: timer_close
*
* Description:
* This function is called when the timer device is closed.
*
****************************************************************************/
static int timer_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct timer_upperhalf_s *upper = inode->i_private;
int ret;
tmrinfo("crefs: %d\n", upper->crefs);
/* Get exclusive access to the device structures */
ret = nxmutex_lock(&upper->lock);
if (ret < 0)
{
return ret;
}
/* Decrement the references to the driver. If the reference count will
* decrement to 0, then uninitialize the driver.
*/
if (upper->crefs > 0)
{
upper->crefs--;
}
nxmutex_unlock(&upper->lock);
return OK;
}
/****************************************************************************
* Name: timer_read
*
* Description:
* A dummy read method. This is provided only to satisfy the VFS layer.
*
****************************************************************************/
static ssize_t timer_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
/* Return zero -- usually meaning end-of-file */
return 0;
}
/****************************************************************************
* Name: timer_write
*
* Description:
* A dummy write method. This is provided only to satisfy the VFS layer.
*
****************************************************************************/
static ssize_t timer_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
return 0;
}
/****************************************************************************
* Name: timer_ioctl
*
* Description:
* The standard ioctl method. This is where ALL of the timer work is
* done.
*
****************************************************************************/
static int timer_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct timer_upperhalf_s *upper;
FAR struct timer_lowerhalf_s *lower;
int ret;
tmrinfo("cmd: %d arg: %ld\n", cmd, arg);
upper = inode->i_private;
DEBUGASSERT(upper != NULL);
lower = upper->lower;
DEBUGASSERT(lower != NULL);
/* Get exclusive access to the device structures */
ret = nxmutex_lock(&upper->lock);
if (ret < 0)
{
return ret;
}
/* Handle built-in ioctl commands */
switch (cmd)
{
/* cmd: TCIOC_START
* Description: Start the timer
* Argument: Ignored
*/
case TCIOC_START:
{
/* Start the timer, resetting the time to the current timeout */
ret = TIMER_START(lower);
}
break;
/* cmd: TCIOC_STOP
* Description: Stop the timer
* Argument: Ignored
*/
case TCIOC_STOP:
{
/* Stop the timer */
ret = TIMER_STOP(lower);
nxsig_cancel_notification(&upper->work);
}
break;
/* cmd: TCIOC_GETSTATUS
* Description: Get the status of the timer.
* Argument: A writeable pointer to struct timer_status_s.
*/
case TCIOC_GETSTATUS:
{
FAR struct timer_status_s *status;
/* Get the current timer status */
status = (FAR struct timer_status_s *)((uintptr_t)arg);
if (status)
{
ret = TIMER_GETSTATUS(lower, status);
}
else
{
ret = -EINVAL;
}
}
break;
/* cmd: TCIOC_SETTIMEOUT
* Description: Reset the timeout to this value
* Argument: A 32-bit timeout value in microseconds.
*
* TODO: pass pointer to uint64 ns? Need to determine if these timers
* are 16 or 32 bit...
*/
case TCIOC_SETTIMEOUT:
{
/* Set a new timeout value (and reset the timer) */
ret = TIMER_SETTIMEOUT(lower, (uint32_t)arg);
}
break;
/* cmd: TCIOC_NOTIFICATION
* Description: Notify application via a signal when the timer expires.
* Argument: signal information
*/
case TCIOC_NOTIFICATION:
{
FAR struct timer_notify_s *notify =
(FAR struct timer_notify_s *)((uintptr_t)arg);
if (notify != NULL)
{
memcpy(&upper->notify, notify, sizeof(*notify));
ret = timer_setcallback((FAR void *)upper, timer_notifier,
(FAR void *)upper);
}
else
{
ret = -EINVAL;
}
}
break;
/* cmd: TCIOC_MAXTIMEOUT
* Description: Get the maximum supported timeout value
* Argument: A 32-bit timeout value in microseconds.
*/
case TCIOC_MAXTIMEOUT:
{
/* Get the maximum supported timeout value */
ret = TIMER_MAXTIMEOUT(lower, (FAR uint32_t *)arg);
}
break;
/* Any unrecognized IOCTL commands might be platform-specific ioctl
* commands
*/
default:
{
tmrinfo("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.
*/
ret = TIMER_IOCTL(lower, cmd, arg);
}
break;
}
nxmutex_unlock(&upper->lock);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: timer_register
*
* Description:
* This function binds an instance of a "lower half" timer driver with the
* "upper half" timer 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 timer
* drivers as "/dev/tc0", "/dev/tc1", 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 timer driver. This
* instance is bound to the timer 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 *timer_register(FAR const char *path,
FAR struct timer_lowerhalf_s *lower)
{
FAR struct timer_upperhalf_s *upper;
int ret;
DEBUGASSERT(path && lower);
tmrinfo("Entry: path=%s\n", path);
/* Allocate the upper-half data structure */
upper = (FAR struct timer_upperhalf_s *)
kmm_zalloc(sizeof(struct timer_upperhalf_s));
if (!upper)
{
tmrerr("ERROR: Upper half allocation failed\n");
goto errout;
}
/* Initialize the timer device structure (it was already zeroed
* by kmm_zalloc()).
*/
upper->lower = lower;
nxmutex_init(&upper->lock);
/* Copy the registration path */
upper->path = strdup(path);
if (!upper->path)
{
tmrerr("ERROR: Path allocation failed\n");
goto errout_with_upper;
}
/* Register the timer device */
ret = register_driver(path, &g_timerops, 0666, upper);
if (ret < 0)
{
tmrerr("ERROR: register_driver failed: %d\n", ret);
goto errout_with_path;
}
return (FAR void *)upper;
errout_with_path:
lib_free(upper->path);
errout_with_upper:
nxmutex_destroy(&upper->lock);
kmm_free(upper);
errout:
return NULL;
}
/****************************************************************************
* Name: timer_unregister
*
* Description:
* This function can be called to disable and unregister the timer
* device driver.
*
* Input Parameters:
* handle - This is the handle that was returned by timer_register()
*
* Returned Value:
* None
*
****************************************************************************/
void timer_unregister(FAR void *handle)
{
FAR struct timer_upperhalf_s *upper;
FAR struct timer_lowerhalf_s *lower;
/* Recover the pointer to the upper-half driver state */
upper = (FAR struct timer_upperhalf_s *)handle;
DEBUGASSERT(upper != NULL && upper->lower != NULL);
lower = upper->lower;
tmrinfo("Unregistering: %s\n", upper->path);
/* Disable the timer */
TIMER_STOP(lower);
nxsig_cancel_notification(&upper->work);
/* Unregister the timer device */
unregister_driver(upper->path);
/* Then free all of the driver resources */
nxmutex_destroy(&upper->lock);
lib_free(upper->path);
kmm_free(upper);
}
/****************************************************************************
* Name: timer_setcallback
*
* Description:
* This function can be called to add a callback into driver-related code
* to handle timer expirations. This is a strictly OS internal interface
* and may NOT be used by application code.
*
* Input Parameters:
* handle - This is the handle that was returned by timer_register()
* callback - The new timer interrupt callback
* arg - Argument to be provided with the callback
*
* Returned Value:
* Zero (OK), if the callback was successfully set, or -ENOSYS if the lower
* half driver does not support the operation.
*
****************************************************************************/
int timer_setcallback(FAR void *handle, tccb_t callback, FAR void *arg)
{
FAR struct timer_upperhalf_s *upper;
FAR struct timer_lowerhalf_s *lower;
/* Recover the pointer to the upper-half driver state */
upper = (FAR struct timer_upperhalf_s *)handle;
DEBUGASSERT(upper != NULL && upper->lower != NULL);
lower = upper->lower;
DEBUGASSERT(lower->ops != NULL);
/* Check if the lower half driver supports the setcallback method */
if (lower->ops->setcallback != NULL) /* Optional */
{
/* Yes.. Defer the handler attachment to the lower half driver */
lower->ops->setcallback(lower, callback, arg);
return OK;
}
return -ENOSYS;
}
#endif /* CONFIG_TIMER */
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