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incubator-nuttx/drivers/rwbuffer.c

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/****************************************************************************
* drivers/rwbuffer.c
*
* Copyright (C) 2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 <stdlib.h>
#include <string.h>
#include <time.h>
#include <assert.h>
#include <semaphore.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/wqueue.h>
#include <nuttx/rwbuffer.h>
#if defined(CONFIG_FS_WRITEBUFFER) || defined(CONFIG_FS_READAHEAD)
/****************************************************************************
* Preprocessor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#ifndef CONFIG_SCHED_WORKQUEUE
# error "Worker thread support is required (CONFIG_SCHED_WORKQUEUE)"
#endif
#ifndef CONFIG_FS_WRDELAY
# define CONFIG_FS_WRDELAY 350
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: rwb_semtake
****************************************************************************/
static void rwb_semtake(sem_t *sem)
{
/* Take the semaphore (perhaps waiting) */
while (sem_wait(sem) != 0)
{
/* The only case that an error should occr here is if
* the wait was awakened by a signal.
*/
ASSERT(errno == EINTR);
}
}
/****************************************************************************
* Name: rwb_semgive
****************************************************************************/
#define rwb_semgive(s) sem_post(s)
/****************************************************************************
* Name: rwb_overlap
****************************************************************************/
static inline boolean rwb_overlap(off_t blockstart1, size_t nblocks1,
off_t blockstart2, size_t nblocks2)
{
off_t blockend1 = blockstart1 + nblocks1;
off_t blockend2 = blockstart2 + nblocks2;
/* If the buffer 1 is wholly outside of buffer 2, return false */
if ((blockend1 < blockstart2) || /* Wholly "below" */
(blockstart1 > blockend2)) /* Wholly "above" */
{
return FALSE;
}
else
{
return TRUE;
}
}
/****************************************************************************
* Name: rwb_resetwrbuffer
****************************************************************************/
#ifdef CONFIG_FS_WRITEBUFFER
static inline void rwb_resetwrbuffer(struct rwbuffer_s *rwb)
{
/* We assume that the caller holds the wrsem */
rwb->wrnblocks = 0;
rwb->wrblockstart = (off_t)-1;
rwb->wrexpectedblock = (off_t)-1;
}
#endif
/****************************************************************************
* Name: rwb_wrflush
****************************************************************************/
#ifdef CONFIG_FS_WRITEBUFFER
static void rwb_wrflush(struct rwbuffer_s *rwb)
{
int ret;
fvdbg("Timeout!\n");
rwb_semtake(&rwb->wrsem);
if (rwb->wrnblocks)
{
fvdbg("Flushing: blockstart=0x%08lx nblocks=%d from buffer=%p\n",
(long)rwb->wrblockstart, rwb->wrnblocks, rwb->wrbuffer);
/* Flush cache. On success, the flush method will return the number
* of blocks written. Anything other than the number requested is
* an error.
*/
ret = rwb->wrflush(rwb->dev, rwb->wrbuffer, rwb->wrblockstart, rwb->wrnblocks);
if (ret != rwb->wrnblocks)
{
fdbg("ERROR: Error flushing write buffer: %d\n", ret);
}
rwb_resetwrbuffer(rwb);
}
rwb_semgive(&rwb->wrsem);
}
#endif
/****************************************************************************
* Name: rwb_wrtimeout
****************************************************************************/
static void rwb_wrtimeout(FAR void *arg)
{
/* The following assumes that the size of a pointer is 4-bytes or less */
FAR struct rwbuffer_s *rwb = (struct rwbuffer_s *)arg;
DEBUGASSERT(rwb != NULL);
/* If a timeout elpases with with write buffer activity, this watchdog
* handler function will be evoked on the thread of execution of the
* worker thread.
*/
rwb_wrflush(rwb);
}
/****************************************************************************
* Name: rwb_wrstarttimeout
****************************************************************************/
static void rwb_wrstarttimeout(FAR struct rwbuffer_s *rwb)
{
/* CONFIG_FS_WRDELAY provides the delay period in milliseconds. CLK_TCK
* provides the clock tick of the system (frequency in Hz).
*/
int ticks = (CONFIG_FS_WRDELAY + CLK_TCK/2) / CLK_TCK;
(void)work_queue(&rwb->work, rwb_wrtimeout, (FAR void *)rwb, ticks);
}
/****************************************************************************
* Name: rwb_wrcanceltimeout
****************************************************************************/
static inline void rwb_wrcanceltimeout(struct rwbuffer_s *rwb)
{
(void)work_cancel(&rwb->work);
}
/****************************************************************************
* Name: rwb_writebuffer
****************************************************************************/
#ifdef CONFIG_FS_WRITEBUFFER
static ssize_t rwb_writebuffer(FAR struct rwbuffer_s *rwb,
off_t startblock, uint32 nblocks,
FAR const ubyte *wrbuffer)
{
int ret;
/* Write writebuffer Logic */
rwb_wrcanceltimeout(rwb);
/* First: Should we flush out our cache? We would do that if (1) we already
* buffering blocks and the next block writing is not in the same sequence,
* or (2) the number of blocks would exceed our allocated buffer capacity
*/
if (((startblock != rwb->wrexpectedblock) && (rwb->wrnblocks)) ||
((rwb->wrnblocks + nblocks) > rwb->wrmaxblocks))
{
fvdbg("writebuffer miss, expected: %08x, given: %08x\n",
rwb->wrexpectedblock, startblock);
/* Flush the write buffer */
ret = rwb->wrflush(rwb, rwb->wrbuffer, rwb->wrblockstart, rwb->wrnblocks);
if (ret < 0)
{
fdbg("ERROR: Error writing multiple from cache: %d\n", -ret);
return ret;
}
rwb_resetwrbuffer(rwb);
}
/* writebuffer is empty? Then initialize it */
if (!rwb->wrnblocks)
{
fvdbg("Fresh cache starting at block: 0x%08x\n", startblock);
rwb->wrblockstart = startblock;
}
/* Add data to cache */
fvdbg("writebuffer: copying %d bytes from %p to %p\n",
nblocks * wrb->blocksize, wrbuffer,
&rwb->wrbuffer[rwb->wrnblocks * rwb->blocksize]);
memcpy(&rwb->wrbuffer[rwb->wrnblocks * rwb->blocksize],
wrbuffer, nblocks * rwb->blocksize);
rwb->wrnblocks += nblocks;
rwb->wrexpectedblock = rwb->wrblockstart + rwb->wrnblocks;
rwb_wrstarttimeout(rwb);
return nblocks;
}
#endif
/****************************************************************************
* Name: rwb_resetrhbuffer
****************************************************************************/
#ifdef CONFIG_FS_READAHEAD
static inline void rwb_resetrhbuffer(struct rwbuffer_s *rwb)
{
/* We assume that the caller holds the readAheadBufferSemphore */
rwb->rhnblocks = 0;
rwb->rhblockstart = (off_t)-1;
}
#endif
/****************************************************************************
* Name: rwb_bufferread
****************************************************************************/
#ifdef CONFIG_FS_READAHEAD
static inline void
rwb_bufferread(struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, ubyte **rdbuffer)
{
/* We assume that (1) the caller holds the readAheadBufferSemphore, and (2)
* that the caller already knows that all of the blocks are in the
* read-ahead buffer.
*/
/* Convert the units from blocks to bytes */
off_t blockoffset = startblock - rwb->rhblockstart;
off_t byteoffset = rwb->blocksize * blockoffset;
size_t nbytes = rwb->blocksize * nblocks;
/* Get the byte address in the read-ahead buffer */
ubyte *rhbuffer = rwb->rhbuffer + byteoffset;
/* Copy the data from the read-ahead buffer into the IO buffer */
memcpy(*rdbuffer, rhbuffer, nbytes);
/* Update the caller's copy for the next address */
*rdbuffer += nbytes;
}
#endif
/****************************************************************************
* Name: rwb_rhreload
****************************************************************************/
#ifdef CONFIG_FS_READAHEAD
static int rwb_rhreload(struct rwbuffer_s *rwb, off_t startblock)
{
/* Get the block number +1 of the last block that will fit in the
* read-ahead buffer
*/
off_t endblock = startblock + rwb->rhmaxblocks;
size_t nblocks;
int ret;
/* Reset the read buffer */
rwb_resetrhbuffer(rwb);
/* Make sure that we don't read past the end of the device */
if (endblock > rwb->nblocks)
{
endblock = rwb->nblocks;
}
nblocks = endblock - startblock;
/* Now perform the read */
ret = rwb->rhreload(rwb->dev, rwb->rhbuffer, startblock, nblocks);
if (ret == nblocks)
{
/* Update information about what is in the read-ahead buffer */
rwb->rhnblocks = nblocks;
rwb->rhblockstart = startblock;
/* The return value is not the number of blocks we asked to be loaded. */
return nblocks;
}
return -EIO;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: rwb_initialize
****************************************************************************/
int rwb_initialize(FAR struct rwbuffer_s *rwb)
{
uint32 allocsize;
/* Sanity checking */
DEBUGASSERT(rwb != NULL);
DEBUGASSERT(rwb->blocksize > 0);
DEBUGASSERT(rwb->nblocks > 0);
DEBUGASSERT(rwb->dev != NULL);
/* Setup so that rwb_uninitialize can handle a failure */
#ifdef CONFIG_FS_WRITEBUFFER
DEBUGASSERT(rwb->wrflush!= NULL);
rwb->wrbuffer = NULL;
#endif
#ifdef CONFIG_FS_READAHEAD
DEBUGASSERT(rwb->rhreload != NULL);
rwb->rhbuffer = NULL;
#endif
#ifdef CONFIG_FS_WRITEBUFFER
fvdbg("Initialize the write buffer\n");
/* Initialize the write buffer access semaphore */
sem_init(&rwb->wrsem, 0, 1);
/* Initialize write buffer parameters */
rwb_resetwrbuffer(rwb);
/* Allocate the write buffer */
rwb->wrbuffer = NULL;
if (rwb->wrmaxblocks > 0)
{
allocsize = rwb->wrmaxblocks * rwb->blocksize;
rwb->wrbuffer = malloc(allocsize);
if (!rwb->wrbuffer)
{
fdbg("Write buffer malloc(%d) failed\n", allocsizee);
return -ENOMEM;
}
}
fvdbg("Write buffer size: %d bytes\n", allocsize);
#endif /* CONFIG_FS_WRITEBUFFER */
#ifdef CONFIG_FS_READAHEAD
fvdbg("Initialize the read-ahead buffer\n");
/* Initialize the read-ahead buffer access semaphore */
sem_init(&rwb->rhsem, 0, 1);
/* Initialize read-ahead buffer parameters */
rwb_resetrhbuffer(rwb);
/* Allocate the read-ahead buffer */
rwb->rhbuffer = NULL;
if (rwb->rhmaxblocks > 0)
{
allocsize = rwb->rhmaxblocks * rwb->blocksize;
rwb->rhbuffer = malloc(allocsize);
if (!rwb->rhbuffer)
{
fdbg("Read-ahead buffer malloc(%d) failed\n", allocsize);
return -ENOMEM;
}
}
fvdbg("Read-ahead buffer size: %d bytes\n", allocsize);
#endif /* CONFIG_FS_READAHEAD */
return 0;
}
/****************************************************************************
* Name: rwb_uninitialize
****************************************************************************/
void rwb_uninitialize(FAR struct rwbuffer_s *rwb)
{
#ifdef CONFIG_FS_WRITEBUFFER
rwb_wrcanceltimeout(rwb);
sem_destroy(&rwb->wrsem);
if (rwb->wrbuffer)
{
free(rwb->wrbuffer);
}
#endif
#ifdef CONFIG_FS_READAHEAD
sem_destroy(&rwb->rhsem);
if (rwb->rhbuffer)
{
free(rwb->rhbuffer);
}
#endif
}
/****************************************************************************
* Name: rwb_read
****************************************************************************/
int rwb_read(FAR struct rwbuffer_s *rwb, off_t startblock, uint32 nblocks,
FAR ubyte *rdbuffer)
{
uint32 remaining;
fvdbg("startblock=%ld nblocks=%ld rdbuffer=%p\n",
(long)startblock, (long)nblocks, rdbuffer);
#ifdef CONFIG_FS_WRITEBUFFER
/* If the new read data overlaps any part of the write buffer, then
* flush the write data onto the physical media before reading. We
* could attempt some more exotic handling -- but this simple logic
* is well-suited for simple streaming applications.
*/
if (rwb->wrmaxblocks > 0)
{
/* If the write buffer overlaps the block(s) requested, then flush the
* write buffer.
*/
rwb_semtake(&rwb->wrsem);
if (rwb_overlap(rwb->wrblockstart, rwb->wrnblocks, startblock, nblocks))
{
rwb_wrflush(rwb);
}
rwb_semgive(&rwb->wrsem);
}
#endif
#ifdef CONFIG_FS_READAHEAD
/* Loop until we have read all of the requested blocks */
rwb_semtake(&rwb->rhsem);
for (remaining = nblocks; remaining > 0;)
{
/* Is there anything in the read-ahead buffer? */
if (rwb->rhnblocks > 0)
{
off_t startblock = startblock;
size_t nbufblocks = 0;
off_t bufferend;
/* Loop for each block we find in the read-head buffer. Count the
* number of buffers that we can read from read-ahead buffer.
*/
bufferend = rwb->rhblockstart + rwb->rhnblocks;
while ((startblock >= rwb->rhblockstart) &&
(startblock < bufferend) &&
(remaining > 0))
{
/* This is one more that we will read from the read ahead buffer */
nbufblocks++;
/* And one less that we will read from the media */
startblock++;
remaining--;
}
/* Then read the data from the read-ahead buffer */
rwb_bufferread(rwb, startblock, nbufblocks, &rdbuffer);
}
/* If we did not get all of the data from the buffer, then we have to refill
* the buffer and try again.
*/
if (remaining > 0)
{
int ret = rwb_rhreload(rwb, startblock);
if (ret < 0)
{
fdbg("ERROR: Failed to fill the read-ahead buffer: %d\n", -ret);
return ret;
}
}
}
/* On success, return the number of blocks that we were requested to read.
* This is for compatibility with the normal return of a block driver read
* method
*/
rwb_semgive(&rwb->rhsem);
return 0;
#else
return rwb->rhreload(rwb->dev, startblock, nblocks, rdbuffer);
#endif
}
/****************************************************************************
* Name: rwb_write
****************************************************************************/
int rwb_write(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR const ubyte *wrbuffer)
{
int ret;
#ifdef CONFIG_FS_READAHEAD
/* If the new write data overlaps any part of the read buffer, then
* flush the data from the read buffer. We could attempt some more
* exotic handling -- but this simple logic is well-suited for simple
* streaming applications.
*/
rwb_semtake(&rwb->rhsem);
if (rwb_overlap(rwb->rhblockstart, rwb->rhnblocks, startblock, nblocks))
{
rwb_resetrhbuffer(rwb);
}
rwb_give(&rwb->rhsem);
#endif
#ifdef CONFIG_FS_WRITEBUFFER
fvdbg("startblock=%d wrbuffer=%p\n", startblock, wrbuffer);
/* Use the block cache unless the buffer size is bigger than block cache */
if (nblocks > rwb->wrmaxblocks)
{
/* First flush the cache */
rwb_semtake(&rwb->wrsem);
rwb_wrflush(rwb);
rwb_semgive(&rwb->wrsem);
/* Then transfer the data directly to the media */
ret = rwb->wrflush(rwb->dev, startblock, nblocks, wrbuffer);
}
else
{
/* Buffer the data in the write buffer */
ret = rwb_writebuffer(rwb, startblock, nblocks, wrbuffer);
}
/* On success, return the number of blocks that we were requested to write.
* This is for compatibility with the normal return of a block driver write
* method
*/
return ret;
#else
return rwb->wrflush(rwb->dev, startblock, nblocks, wrbuffer);
#endif
}
/****************************************************************************
* Name: rwb_mediaremoved
****************************************************************************/
/* The following function is called when media is removed */
int rwb_mediaremoved(FAR struct rwbuffer_s *rwb)
{
#ifdef CONFIG_FS_WRITEBUFFER
rwb_semtake(&rwb->wrsem);
rwb_resetwrbuffer(rwb);
rwb_semgive(&rwb->wrsem);
#endif
#ifdef CONFIG_FS_READAHEAD
rwb_semtake(&rwb->rhsem);
rwb_resetrhbuffer(rwb);
rwb_semgive(&rwb->rhsem);
#endif
return 0;
}
#endif /* CONFIG_FS_WRITEBUFFER || CONFIG_FS_READAHEAD */
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