/**************************************************************************** * fs/vfs/fs_timerfd.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 #include #include #include #include #include #include #include #include #include #include #include #include "clock/clock.h" #include "inode/inode.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #ifndef CONFIG_TIMER_FD_VFS_PATH #define CONFIG_TIMER_FD_VFS_PATH "/var/timer" #endif #ifndef CONFIG_TIMER_FD_NPOLLWAITERS /* Maximum number of threads than can be waiting for POLL events */ #define CONFIG_TIMER_FD_NPOLLWAITERS 2 #endif #define TIMER_FD_WORK LPWORK /**************************************************************************** * Private Types ****************************************************************************/ typedef struct timerfd_waiter_sem_s { sem_t sem; struct timerfd_waiter_sem_s *next; } timerfd_waiter_sem_t; /* This structure describes the internal state of the driver */ struct timerfd_priv_s { sem_t exclsem; /* Enforces device exclusive access */ timerfd_waiter_sem_t *rdsems; /* List of blocking readers */ int clock; /* Clock to use as the timing base */ int delay; /* If non-zero, used to reset repetitive * timers */ struct wdog_s wdog; /* The watchdog that provides the timing */ struct work_s work; /* For deferred timeout operations */ timerfd_t counter; /* timerfd counter */ spinlock_t lock; /* timerfd counter specific lock */ unsigned int minor; /* timerfd minor number */ uint8_t crefs; /* References counts on timerfd (max: 255) */ /* The following is a list if poll structures of threads waiting for * driver events. */ #ifdef CONFIG_TIMER_FD_POLL FAR struct pollfd *fds[CONFIG_TIMER_FD_NPOLLWAITERS]; #endif }; /**************************************************************************** * Private Function Prototypes ****************************************************************************/ static int timerfd_open(FAR struct file *filep); static int timerfd_close(FAR struct file *filep); static ssize_t timerfd_read(FAR struct file *filep, FAR char *buffer, size_t len); #ifdef CONFIG_TIMER_FD_POLL static int timerfd_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup); static void timerfd_pollnotify(FAR struct timerfd_priv_s *dev, pollevent_t eventset); #endif static int timerfd_blocking_io(FAR struct timerfd_priv_s *dev, timerfd_waiter_sem_t *sem, FAR timerfd_waiter_sem_t **slist); static unsigned int timerfd_get_unique_minor(void); static void timerfd_release_minor(unsigned int minor); static FAR struct timerfd_priv_s *timerfd_allocdev(void); static void timerfd_destroy(FAR struct timerfd_priv_s *dev); static void timerfd_timeout_work(FAR void *arg); static void timerfd_timeout(wdparm_t idev); /**************************************************************************** * Private Data ****************************************************************************/ static const struct file_operations g_timerfd_fops = { timerfd_open, /* open */ timerfd_close, /* close */ timerfd_read, /* read */ NULL, /* write */ NULL, /* seek */ NULL, /* ioctl */ #ifdef CONFIG_TIMER_FD_POLL timerfd_poll /* poll */ #else NULL /* poll */ #endif #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS , NULL /* unlink */ #endif }; /**************************************************************************** * Private Functions ****************************************************************************/ static FAR struct timerfd_priv_s *timerfd_allocdev(void) { FAR struct timerfd_priv_s *dev; dev = (FAR struct timerfd_priv_s *) kmm_zalloc(sizeof(struct timerfd_priv_s)); if (dev) { /* Initialize the private structure */ nxsem_init(&dev->exclsem, 0, 0); } return dev; } static void timerfd_destroy(FAR struct timerfd_priv_s *dev) { wd_cancel(&dev->wdog); work_cancel(TIMER_FD_WORK, &dev->work); nxsem_destroy(&dev->exclsem); kmm_free(dev); } static timerfd_t timerfd_get_counter(FAR struct timerfd_priv_s *dev) { timerfd_t counter; irqstate_t intflags; intflags = spin_lock_irqsave(&dev->lock); counter = dev->counter; spin_unlock_irqrestore(&dev->lock, intflags); return counter; } #ifdef CONFIG_TIMER_FD_POLL static void timerfd_pollnotify(FAR struct timerfd_priv_s *dev, pollevent_t eventset) { FAR struct pollfd *fds; int i; for (i = 0; i < CONFIG_TIMER_FD_NPOLLWAITERS; i++) { fds = dev->fds[i]; if (fds) { fds->revents |= eventset & fds->events; if (fds->revents != 0) { nxsem_post(fds->sem); } } } } #endif static unsigned int timerfd_get_unique_minor(void) { static unsigned int minor; return minor++; } static void timerfd_release_minor(unsigned int minor) { } static int timerfd_open(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct timerfd_priv_s *priv = inode->i_private; int ret; /* Get exclusive access to the device structures */ ret = nxsem_wait(&priv->exclsem); if (ret < 0) { return ret; } finfo("crefs: %d <%s>\n", priv->crefs, inode->i_name); if (priv->crefs >= 255) { /* More than 255 opens; uint8_t would overflow to zero */ ret = -EMFILE; } else { /* Save the new open count on success */ priv->crefs += 1; ret = OK; } nxsem_post(&priv->exclsem); return ret; } static int timerfd_close(FAR struct file *filep) { int ret; FAR struct inode *inode = filep->f_inode; FAR struct timerfd_priv_s *priv = inode->i_private; /* devpath: TIMER_FD_VFS_PATH + /tfd (4) + %u (10) + null char (1) */ char devpath[sizeof(CONFIG_TIMER_FD_VFS_PATH) + 4 + 10 + 1]; /* Get exclusive access to the device structures */ ret = nxsem_wait(&priv->exclsem); if (ret < 0) { return ret; } finfo("crefs: %d <%s>\n", priv->crefs, inode->i_name); /* Decrement the references to the driver. If the reference count will * decrement to 0, then uninitialize the driver. */ if (priv->crefs > 1) { /* Just decrement the reference count and release the semaphore */ priv->crefs--; nxsem_post(&priv->exclsem); return OK; } /* Re-create the path to the driver. */ finfo("destroy\n"); sprintf(devpath, CONFIG_TIMER_FD_VFS_PATH "/tfd%u", priv->minor); /* Will be unregistered later after close is done */ unregister_driver(devpath); DEBUGASSERT(priv->exclsem.semcount == 0); timerfd_release_minor(priv->minor); timerfd_destroy(priv); return OK; } static int timerfd_blocking_io(FAR struct timerfd_priv_s *dev, timerfd_waiter_sem_t *sem, FAR timerfd_waiter_sem_t **slist) { int ret; sem->next = *slist; *slist = sem; nxsem_post(&dev->exclsem); /* Wait for timerfd to notify */ ret = nxsem_wait(&sem->sem); if (ret < 0) { /* Interrupted wait, unregister semaphore * TODO ensure that exclsem wait does not fail (ECANCELED) */ nxsem_wait_uninterruptible(&dev->exclsem); timerfd_waiter_sem_t *cur_sem = *slist; if (cur_sem == sem) { *slist = sem->next; } else { while (cur_sem) { if (cur_sem->next == sem) { cur_sem->next = sem->next; break; } } } nxsem_post(&dev->exclsem); return ret; } return nxsem_wait(&dev->exclsem); } static ssize_t timerfd_read(FAR struct file *filep, FAR char *buffer, size_t len) { FAR struct inode *inode = filep->f_inode; FAR struct timerfd_priv_s *dev = inode->i_private; irqstate_t intflags; ssize_t ret; if (len < sizeof(timerfd_t) || buffer == NULL) { return -EINVAL; } ret = nxsem_wait(&dev->exclsem); if (ret < 0) { return ret; } /* Wait for an incoming event */ if (timerfd_get_counter(dev) == 0) { if (filep->f_oflags & O_NONBLOCK) { nxsem_post(&dev->exclsem); return -EAGAIN; } timerfd_waiter_sem_t sem; nxsem_init(&sem.sem, 0, 0); nxsem_set_protocol(&sem.sem, SEM_PRIO_NONE); do { ret = timerfd_blocking_io(dev, &sem, &dev->rdsems); if (ret < 0) { nxsem_destroy(&sem.sem); return ret; } } while (timerfd_get_counter(dev) == 0); nxsem_destroy(&sem.sem); } /* Device ready for read. Ensure that interrupts are disabled and we * do not lose counts if expiration occurs after read, but before setting * counter to zero */ intflags = spin_lock_irqsave(&dev->lock); *(FAR timerfd_t *)buffer = dev->counter; dev->counter = 0; spin_unlock_irqrestore(&dev->lock, intflags); nxsem_post(&dev->exclsem); return sizeof(timerfd_t); } #ifdef CONFIG_TIMER_FD_POLL static int timerfd_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup) { FAR struct inode *inode = filep->f_inode; FAR struct timerfd_priv_s *dev = inode->i_private; int ret; int i; ret = nxsem_wait(&dev->exclsem); if (ret < 0) { return ret; } ret = OK; if (!setup) { /* This is a request to tear down the poll. */ FAR struct pollfd **slot = (FAR struct pollfd **)fds->priv; /* Remove all memory of the poll setup */ *slot = NULL; fds->priv = NULL; goto out; } /* This is a request to set up the poll. Find an available * slot for the poll structure reference */ for (i = 0; i < CONFIG_TIMER_FD_NPOLLWAITERS; i++) { /* Find an available slot */ if (!dev->fds[i]) { /* Bind the poll structure and this slot */ dev->fds[i] = fds; fds->priv = &dev->fds[i]; break; } } if (i >= CONFIG_TIMER_FD_NPOLLWAITERS) { fds->priv = NULL; ret = -EBUSY; goto out; } /* Notify the POLLIN event if the counter is not zero */ if (timerfd_get_counter(dev) > 0) { timerfd_pollnotify(dev, POLLIN); } out: nxsem_post(&dev->exclsem); return ret; } #endif static void timerfd_timeout_work(FAR void *arg) { FAR struct timerfd_priv_s *dev = (FAR struct timerfd_priv_s *)arg; int ret; ret = nxsem_wait_uninterruptible(&dev->exclsem); if (ret < 0) { wd_cancel(&dev->wdog); return; } #ifdef CONFIG_TIMER_FD_POLL /* Notify all poll/select waiters */ timerfd_pollnotify(dev, POLLIN); #endif /* Notify all of the waiting readers */ timerfd_waiter_sem_t *cur_sem = dev->rdsems; while (cur_sem != NULL) { nxsem_post(&cur_sem->sem); cur_sem = cur_sem->next; } dev->rdsems = NULL; nxsem_post(&dev->exclsem); } static void timerfd_timeout(wdparm_t idev) { FAR struct timerfd_priv_s *dev = (FAR struct timerfd_priv_s *)idev; irqstate_t intflags; /* Disable interrupts to ensure that expiration counter is accessed * atomically */ intflags = spin_lock_irqsave(&dev->lock); /* Increment timer expiration counter */ dev->counter++; work_queue(TIMER_FD_WORK, &dev->work, timerfd_timeout_work, dev, 0); /* If this is a repetitive timer, then restart the watchdog */ if (dev->delay) { wd_start(&dev->wdog, dev->delay, timerfd_timeout, idev); } spin_unlock_irqrestore(&dev->lock, intflags); } /**************************************************************************** * Public Functions ****************************************************************************/ int timerfd_create(int clockid, int flags) { FAR struct timerfd_priv_s *new_dev; int new_fd; int ret; /* Sanity checks. */ if (clockid != CLOCK_REALTIME #ifdef CONFIG_CLOCK_MONOTONIC && clockid != CLOCK_MONOTONIC && clockid != CLOCK_BOOTTIME #endif /* CONFIG_CLOCK_MONOTONIC */ ) { ret = -EINVAL; goto errout; } /* devpath: TIMER_FD_VFS_PATH + /tfd (4) + %u (10) + null char (1) */ char devpath[sizeof(CONFIG_TIMER_FD_VFS_PATH) + 4 + 10 + 1]; /* Allocate instance data for this driver */ new_dev = timerfd_allocdev(); if (new_dev == NULL) { /* Failed to allocate new device */ ret = -ENOMEM; goto errout; } /* Initialize the timer instance */ new_dev->clock = clockid; new_dev->crefs = 1; new_dev->delay = 0; new_dev->counter = 0; /* Request a unique minor device number */ new_dev->minor = timerfd_get_unique_minor(); /* Get device path */ sprintf(devpath, CONFIG_TIMER_FD_VFS_PATH "/tfd%u", new_dev->minor); /* Register the driver */ ret = register_driver(devpath, &g_timerfd_fops, 0444, new_dev); if (ret < 0) { ferr("Failed to register new device %s: %d\n", devpath, ret); ret = -ENODEV; goto errout_release_minor; } /* Device is ready for use */ nxsem_post(&new_dev->exclsem); /* Try open new device */ new_fd = nx_open(devpath, O_RDONLY | (flags & (TFD_NONBLOCK | TFD_CLOEXEC))); if (new_fd < 0) { ret = new_fd; goto errout_unregister_driver; } return new_fd; errout_unregister_driver: unregister_driver(devpath); errout_release_minor: timerfd_release_minor(new_dev->minor); timerfd_destroy(new_dev); errout: set_errno(-ret); return ERROR; } int timerfd_settime(int fd, int flags, FAR const struct itimerspec *new_value, FAR struct itimerspec *old_value) { FAR struct file *filep; FAR struct timerfd_priv_s *dev; irqstate_t intflags; sclock_t delay; int ret; /* Some sanity checks */ if (!new_value) { ret = -EFAULT; goto errout; } if (flags && (flags & TFD_TIMER_ABSTIME) == 0) { ret = -EINVAL; goto errout; } /* Get file pointer by file descriptor */ ret = fs_getfilep(fd, &filep); if (ret < 0) { goto errout; } /* Check fd come from us */ if (!filep->f_inode || filep->f_inode->u.i_ops != &g_timerfd_fops) { ret = -EINVAL; goto errout; } dev = (FAR struct timerfd_priv_s *)filep->f_inode->i_private; if (old_value) { /* Get the number of ticks before the underlying watchdog expires */ delay = wd_gettime(&dev->wdog); /* Convert that to a struct timespec and return it */ clock_ticks2time(delay, &old_value->it_value); clock_ticks2time(dev->delay, &old_value->it_interval); } /* Disable interrupts here to ensure that expiration counter is accessed * atomicaly and timeout work is canceled with the same sequence */ intflags = spin_lock_irqsave(&dev->lock); /* Disarm the timer (in case the timer was already armed when * timerfd_settime() is called). */ wd_cancel(&dev->wdog); /* Cancel notification work */ work_cancel(TIMER_FD_WORK, &dev->work); /* Clear expiration counter */ dev->counter = 0; /* If the it_value member of value is zero, the timer will not be * re-armed */ if (new_value->it_value.tv_sec <= 0 && new_value->it_value.tv_nsec <= 0) { spin_unlock_irqrestore(NULL, intflags); return OK; } /* Setup up any repetitive timer */ if (new_value->it_interval.tv_sec > 0 || new_value->it_interval.tv_nsec > 0) { clock_time2ticks(&new_value->it_interval, &delay); /* REVISIT: Should delay be sclock_t? */ dev->delay = (int)delay; } else { dev->delay = 0; } /* We need to disable timer interrupts through the following section so * that the system timer is stable. */ /* Check if abstime is selected */ if ((flags & TFD_TIMER_ABSTIME) != 0) { /* Calculate a delay corresponding to the absolute time in 'value' */ clock_abstime2ticks(dev->clock, &new_value->it_value, &delay); } else { /* Calculate a delay assuming that 'value' holds the relative time * to wait. We have internal knowledge that clock_time2ticks always * returns success. */ clock_time2ticks(&new_value->it_value, &delay); } /* If the time is in the past or now, then set up the next interval * instead (assuming a repetitive timer). */ if (delay <= 0) { delay = dev->delay; } /* Then start the watchdog */ if (delay > 0) { ret = wd_start(&dev->wdog, delay, timerfd_timeout, (wdparm_t)dev); if (ret < 0) { spin_unlock_irqrestore(&dev->lock, intflags); goto errout; } } spin_unlock_irqrestore(&dev->lock, intflags); return OK; errout: set_errno(-ret); return ERROR; } int timerfd_gettime(int fd, FAR struct itimerspec *curr_value) { FAR struct file *filep; FAR struct timerfd_priv_s *dev; sclock_t ticks; int ret; /* Some sanity checks */ if (!curr_value) { ret = -EFAULT; goto errout; } /* Get file pointer by file descriptor */ ret = fs_getfilep(fd, &filep); if (ret < 0) { goto errout; } /* Check fd come from us */ if (!filep->f_inode || filep->f_inode->u.i_ops != &g_timerfd_fops) { ret = -EINVAL; goto errout; } dev = (FAR struct timerfd_priv_s *)filep->f_inode->i_private; /* Get the number of ticks before the underlying watchdog expires */ ticks = wd_gettime(&dev->wdog); /* Convert that to a struct timespec and return it */ clock_ticks2time(ticks, &curr_value->it_value); clock_ticks2time(dev->delay, &curr_value->it_interval); return OK; errout: set_errno(-ret); return ERROR; }