/**************************************************************************** * drivers/rwbuffer.c * * Copyright (C) 2009, 2011 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #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 bool 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(LPWORK, &rwb->work, rwb_wrtimeout, (FAR void *)rwb, ticks); } /**************************************************************************** * Name: rwb_wrcanceltimeout ****************************************************************************/ static inline void rwb_wrcanceltimeout(struct rwbuffer_s *rwb) { (void)work_cancel(LPWORK, &rwb->work); } /**************************************************************************** * Name: rwb_writebuffer ****************************************************************************/ #ifdef CONFIG_FS_WRITEBUFFER static ssize_t rwb_writebuffer(FAR struct rwbuffer_s *rwb, off_t startblock, uint32_t nblocks, FAR const uint8_t *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, uint8_t **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 */ uint8_t *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_t 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 = kmalloc(allocsize); if (!rwb->wrbuffer) { fdbg("Write buffer kmalloc(%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 = kmalloc(allocsize); if (!rwb->rhbuffer) { fdbg("Read-ahead buffer kmalloc(%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) { kfree(rwb->wrbuffer); } #endif #ifdef CONFIG_FS_READAHEAD sem_destroy(&rwb->rhsem); if (rwb->rhbuffer) { kfree(rwb->rhbuffer); } #endif } /**************************************************************************** * Name: rwb_read ****************************************************************************/ int rwb_read(FAR struct rwbuffer_s *rwb, off_t startblock, uint32_t nblocks, FAR uint8_t *rdbuffer) { uint32_t 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 uint8_t *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 * * Description: * 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 */