2016-03-17 21:45:35 +01:00
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/****************************************************************************
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* drivers/syslog/note_driver.c
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*
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* Copyright (C) 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <sched.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/sched_note.h>
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#include <nuttx/fs/fs.h>
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#if defined(CONFIG_SCHED_INSTRUMENTATION_BUFFER) && \
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defined(CONFIG_DRIVER_NOTE)
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static ssize_t note_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations note_fops =
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{
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2019-05-22 02:57:54 +02:00
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NULL, /* open */
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NULL, /* close */
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2016-03-17 21:45:35 +01:00
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note_read, /* read */
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2019-05-22 02:57:54 +02:00
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NULL, /* write */
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NULL, /* seek */
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NULL, /* ioctl */
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NULL /* poll */
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2016-03-17 21:45:35 +01:00
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, 0 /* unlink */
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2017-06-28 21:17:17 +02:00
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#endif
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2016-03-17 21:45:35 +01:00
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: note_read
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****************************************************************************/
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static ssize_t note_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen)
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{
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ssize_t notelen;
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ssize_t retlen ;
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DEBUGASSERT(filep != 0 && buffer != NULL && buflen > 0);
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/* Then loop, adding as many notes as possible to the user buffer. */
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retlen = 0;
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sched_lock();
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do
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{
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/* Get the next note (removing it from the buffer) */
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notelen = sched_note_get((FAR uint8_t *)buffer, buflen);
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if (notelen < 0)
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{
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/* We were unable to read the next note, probably because it will
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* not fit into the user buffer.
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*/
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if (retlen == 0)
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{
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/* If nothing was read then report the error. Otherwise,
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* just silently drop the note.
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*/
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retlen = notelen;
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}
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break;
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}
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/* Update pointers from the note that was transferred */
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retlen += notelen;
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buffer += notelen;
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buflen -= notelen;
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/* Will the next note fit? There is a race here and even if the next
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* note will fit, it may fail still when sched_note_get() is called.
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*
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* It won't fit (or an error occurred). Return what we have without
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* trying to get the next note (which would cause it to be deleted).
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*/
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notelen = sched_note_size();
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}
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while (notelen > 0 && notelen <= buflen);
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sched_unlock();
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return retlen;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: note_register
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*
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* Description:
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* Register a serial driver at /dev/note that can be used by an
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2019-09-16 15:48:48 +02:00
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* application to read data from the circular note buffer.
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2016-03-17 21:45:35 +01:00
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*
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* Input Parameters:
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* None.
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*
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* Returned Value:
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* Zero is returned if the circular buffer is empty. Otherwise, a negated
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* errno value is returned.
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*
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****************************************************************************/
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int note_register(void)
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{
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return register_driver("/dev/note", ¬e_fops, 0666, NULL);
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}
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2019-05-22 02:57:54 +02:00
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#endif /* CONFIG_SCHED_INSTRUMENTATION_BUFFER && CONFIG_DRIVER_NOTE */
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