nuttx/drivers/note/noteram_driver.c

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/****************************************************************************
* drivers/note/noteram_driver.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 <sched.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <nuttx/spinlock.h>
#include <nuttx/sched.h>
#include <nuttx/sched_note.h>
#include <nuttx/note/note_driver.h>
#include <nuttx/note/noteram_driver.h>
#include <nuttx/fs/fs.h>
/****************************************************************************
* Private Types
****************************************************************************/
struct noteram_info_s
{
unsigned int ni_overwrite;
volatile unsigned int ni_head;
volatile unsigned int ni_tail;
volatile unsigned int ni_read;
uint8_t ni_buffer[CONFIG_DRIVER_NOTERAM_BUFSIZE];
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int noteram_open(FAR struct file *filep);
static ssize_t noteram_read(FAR struct file *filep,
FAR char *buffer, size_t buflen);
static int noteram_ioctl(struct file *filep, int cmd, unsigned long arg);
static void noteram_add(FAR struct note_driver_s *drv,
FAR const void *note, size_t len);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_noteram_fops =
{
noteram_open, /* open */
NULL, /* close */
noteram_read, /* read */
NULL, /* write */
NULL, /* seek */
noteram_ioctl, /* ioctl */
NULL /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL /* unlink */
#endif
};
static struct noteram_info_s g_noteram_info =
{
#ifdef CONFIG_DRIVER_NOTERAM_DEFAULT_NOOVERWRITE
NOTERAM_MODE_OVERWRITE_DISABLE
#else
NOTERAM_MODE_OVERWRITE_ENABLE
#endif
};
static const struct note_driver_ops_s g_noteram_ops =
{
noteram_add
};
#ifdef CONFIG_SMP
static volatile spinlock_t g_noteram_lock;
#endif
/****************************************************************************
* Public Data
****************************************************************************/
struct note_driver_s g_noteram_driver =
{
&g_noteram_ops,
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: noteram_buffer_clear
*
* Description:
* Clear all contents of the circular buffer.
*
* Input Parameters:
* None.
*
* Returned Value:
* None.
*
****************************************************************************/
static void noteram_buffer_clear(void)
{
irqstate_t flags;
flags = enter_critical_section();
g_noteram_info.ni_tail = g_noteram_info.ni_head;
g_noteram_info.ni_read = g_noteram_info.ni_head;
if (g_noteram_info.ni_overwrite == NOTERAM_MODE_OVERWRITE_OVERFLOW)
{
g_noteram_info.ni_overwrite = NOTERAM_MODE_OVERWRITE_DISABLE;
}
leave_critical_section(flags);
}
/****************************************************************************
* Name: noteram_next
*
* Description:
* Return the circular buffer index at offset from the specified index
* value, handling wraparound
*
* Input Parameters:
* ndx - Old circular buffer index
*
* Returned Value:
* New circular buffer index
*
****************************************************************************/
static inline unsigned int noteram_next(unsigned int ndx,
unsigned int offset)
{
ndx += offset;
if (ndx >= CONFIG_DRIVER_NOTERAM_BUFSIZE)
{
ndx -= CONFIG_DRIVER_NOTERAM_BUFSIZE;
}
return ndx;
}
/****************************************************************************
* Name: noteram_length
*
* Description:
* Length of data currently in circular buffer.
*
* Input Parameters:
* None
*
* Returned Value:
* Length of data currently in circular buffer.
*
****************************************************************************/
static unsigned int noteram_length(void)
{
unsigned int head = g_noteram_info.ni_head;
unsigned int tail = g_noteram_info.ni_tail;
if (tail > head)
{
head += CONFIG_DRIVER_NOTERAM_BUFSIZE;
}
return head - tail;
}
/****************************************************************************
* Name: noteram_unread_length
*
* Description:
* Length of unread data currently in circular buffer.
*
* Input Parameters:
* None
*
* Returned Value:
* Length of unread data currently in circular buffer.
*
****************************************************************************/
static unsigned int noteram_unread_length(void)
{
unsigned int head = g_noteram_info.ni_head;
unsigned int read = g_noteram_info.ni_read;
if (read > head)
{
head += CONFIG_DRIVER_NOTERAM_BUFSIZE;
}
return head - read;
}
/****************************************************************************
* Name: noteram_remove
*
* Description:
* Remove the variable length note from the tail of the circular buffer
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
* Assumptions:
* We are within a critical section.
*
****************************************************************************/
static void noteram_remove(void)
{
unsigned int tail;
unsigned int length;
/* Get the tail index of the circular buffer */
tail = g_noteram_info.ni_tail;
DEBUGASSERT(tail < CONFIG_DRIVER_NOTERAM_BUFSIZE);
/* Get the length of the note at the tail index */
length = g_noteram_info.ni_buffer[tail];
DEBUGASSERT(length <= noteram_length());
/* Increment the tail index to remove the entire note from the circular
* buffer.
*/
if (g_noteram_info.ni_read == g_noteram_info.ni_tail)
{
/* The read index also needs increment. */
g_noteram_info.ni_read = noteram_next(tail, length);
}
g_noteram_info.ni_tail = noteram_next(tail, length);
}
/****************************************************************************
* Name: noteram_get
*
* Description:
* Get the next note from the read index of the circular buffer.
*
* Input Parameters:
* buffer - Location to return the next note
* buflen - The length of the user provided buffer.
*
* Returned Value:
* On success, the positive, non-zero length of the return note is
* provided. Zero is returned only if the circular buffer is empty. A
* negated errno value is returned in the event of any failure.
*
****************************************************************************/
static ssize_t noteram_get(FAR uint8_t *buffer, size_t buflen)
{
FAR struct note_common_s *note;
irqstate_t flags;
unsigned int remaining;
unsigned int read;
ssize_t notelen;
size_t circlen;
DEBUGASSERT(buffer != NULL);
flags = enter_critical_section();
/* Verify that the circular buffer is not empty */
circlen = noteram_unread_length();
if (circlen <= 0)
{
notelen = 0;
goto errout_with_csection;
}
/* Get the read index of the circular buffer */
read = g_noteram_info.ni_read;
DEBUGASSERT(read < CONFIG_DRIVER_NOTERAM_BUFSIZE);
/* Get the length of the note at the read index */
note = (FAR struct note_common_s *)&g_noteram_info.ni_buffer[read];
notelen = note->nc_length;
DEBUGASSERT(notelen <= circlen);
/* Is the user buffer large enough to hold the note? */
if (buflen < notelen)
{
/* Skip the large note so that we do not get constipated. */
g_noteram_info.ni_read = noteram_next(read, notelen);
/* and return an error */
notelen = -EFBIG;
goto errout_with_csection;
}
/* Loop until the note has been transferred to the user buffer */
remaining = (unsigned int)notelen;
while (remaining > 0)
{
/* Copy the next byte at the read index */
*buffer++ = g_noteram_info.ni_buffer[read];
/* Adjust indices and counts */
read = noteram_next(read, 1);
remaining--;
}
g_noteram_info.ni_read = read;
errout_with_csection:
leave_critical_section(flags);
return notelen;
}
/****************************************************************************
* Name: noteram_size
*
* Description:
* Return the size of the next note at the read index of the circular
* buffer.
*
* Input Parameters:
* None.
*
* Returned Value:
* Zero is returned if the circular buffer is empty. Otherwise, the size
* of the next note is returned.
*
****************************************************************************/
static ssize_t noteram_size(void)
{
FAR struct note_common_s *note;
irqstate_t flags;
unsigned int read;
ssize_t notelen;
size_t circlen;
flags = enter_critical_section();
/* Verify that the circular buffer is not empty */
circlen = noteram_unread_length();
if (circlen <= 0)
{
notelen = 0;
goto errout_with_csection;
}
/* Get the read index of the circular buffer */
read = g_noteram_info.ni_read;
DEBUGASSERT(read < CONFIG_DRIVER_NOTERAM_BUFSIZE);
/* Get the length of the note at the read index */
note = (FAR struct note_common_s *)&g_noteram_info.ni_buffer[read];
notelen = note->nc_length;
DEBUGASSERT(notelen <= circlen);
errout_with_csection:
leave_critical_section(flags);
return notelen;
}
/****************************************************************************
* Name: noteram_open
****************************************************************************/
static int noteram_open(FAR struct file *filep)
{
/* Reset the read index of the circular buffer */
g_noteram_info.ni_read = g_noteram_info.ni_tail;
return OK;
}
/****************************************************************************
* Name: noteram_read
****************************************************************************/
static ssize_t noteram_read(FAR struct file *filep,
FAR char *buffer, size_t buflen)
{
ssize_t notelen;
ssize_t retlen ;
DEBUGASSERT(filep != 0 && buffer != NULL && buflen > 0);
/* Then loop, adding as many notes as possible to the user buffer. */
retlen = 0;
sched_lock();
do
{
/* Get the next note (removing it from the buffer) */
notelen = noteram_get((FAR uint8_t *)buffer, buflen);
if (notelen < 0)
{
/* We were unable to read the next note, probably because it will
* not fit into the user buffer.
*/
if (retlen == 0)
{
/* If nothing was read then report the error. Otherwise,
* just silently drop the note.
*/
retlen = notelen;
}
break;
}
/* Update pointers from the note that was transferred */
retlen += notelen;
buffer += notelen;
buflen -= notelen;
/* Will the next note fit? There is a race here and even if the next
* note will fit, it may fail still when noteram_get() is called.
*
* It won't fit (or an error occurred). Return what we have without
* trying to get the next note (which would cause it to be deleted).
*/
notelen = noteram_size();
}
while (notelen > 0 && notelen <= buflen);
sched_unlock();
return retlen;
}
/****************************************************************************
* Name: noteram_ioctl
****************************************************************************/
static int noteram_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
int ret = -ENOSYS;
/* Handle the ioctl commands */
switch (cmd)
{
/* NOTERAM_CLEAR
* - Clear all contents of the circular buffer
* Argument: Ignored
*/
case NOTERAM_CLEAR:
noteram_buffer_clear();
ret = OK;
break;
/* NOTERAM_GETMODE
* - Get overwrite mode
* Argument: A writable pointer to unsigned int
*/
case NOTERAM_GETMODE:
if (arg == 0)
{
ret = -EINVAL;
}
else
{
*(unsigned int *)arg = g_noteram_info.ni_overwrite;
ret = OK;
}
break;
/* NOTERAM_SETMODE
* - Set overwrite mode
* Argument: A read-only pointer to unsigned int
*/
case NOTERAM_SETMODE:
if (arg == 0)
{
ret = -EINVAL;
}
else
{
g_noteram_info.ni_overwrite = *(unsigned int *)arg;
ret = OK;
}
break;
#ifdef NOTERAM_GETTASKNAME
/* NOTERAM_GETTASKNAME
* - Get task name string
* Argument: A writable pointer to struct note_get_taskname_s
* Result: If -ESRCH, the corresponding task name doesn't
* exist.
*/
case NOTERAM_GETTASKNAME:
{
FAR struct noteram_get_taskname_s *param;
if (arg == 0)
{
ret = -EINVAL;
break;
}
param = (FAR struct noteram_get_taskname_s *)arg;
ret = note_get_taskname(param->pid, param->taskname);
}
break;
#endif
default:
break;
}
return ret;
}
/****************************************************************************
* Name: noteram_add
*
* Description:
* Add the variable length note to the transport layer
*
* Input Parameters:
* note - The note buffer
* notelen - The buffer length
*
* Returned Value:
* None
*
* Assumptions:
* We are within a critical section.
*
****************************************************************************/
static void noteram_add(FAR struct note_driver_s *drv,
FAR const void *note, size_t notelen)
{
FAR const char *buf = note;
unsigned int head;
unsigned int next;
irqstate_t flags;
flags = up_irq_save();
#ifdef CONFIG_SMP
spin_lock_wo_note(&g_noteram_lock);
#endif
if (g_noteram_info.ni_overwrite == NOTERAM_MODE_OVERWRITE_OVERFLOW)
{
#ifdef CONFIG_SMP
spin_unlock_wo_note(&g_noteram_lock);
#endif
up_irq_restore(flags);
return;
}
/* Get the index to the head of the circular buffer */
DEBUGASSERT(note != NULL && notelen < CONFIG_DRIVER_NOTERAM_BUFSIZE);
head = g_noteram_info.ni_head;
/* Loop until all bytes have been transferred to the circular buffer */
while (notelen > 0)
{
/* Get the next head index. Would it collide with the current tail
* index?
*/
next = noteram_next(head, 1);
if (next == g_noteram_info.ni_tail)
{
if (g_noteram_info.ni_overwrite == NOTERAM_MODE_OVERWRITE_DISABLE)
{
/* Stop recording if not in overwrite mode */
g_noteram_info.ni_overwrite = NOTERAM_MODE_OVERWRITE_OVERFLOW;
#ifdef CONFIG_SMP
spin_unlock_wo_note(&g_noteram_lock);
#endif
up_irq_restore(flags);
return;
}
/* Yes, then remove the note at the tail index */
noteram_remove();
}
/* Save the next byte at the head index */
g_noteram_info.ni_buffer[head] = *buf++;
head = next;
notelen--;
}
g_noteram_info.ni_head = head;
#ifdef CONFIG_SMP
spin_unlock_wo_note(&g_noteram_lock);
#endif
up_irq_restore(flags);
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: noteram_register
*
* Description:
* Register a serial driver at /dev/note/ram that can be used by an
* application to read data from the circular note buffer.
*
* Input Parameters:
* None.
*
* Returned Value:
* Zero on succress. A negated errno value is returned on a failure.
*
****************************************************************************/
int noteram_register(void)
{
return register_driver("/dev/note/ram", &g_noteram_fops, 0666, NULL);
}