Rearchitecting of some MTD, partition, SMART interfaces, and FLASH drivers to: Better use the byte write capbility when available and to use smaller erase sectors for the erase sector size when available).

5 files changed, 391 insertions, 345 deletions

diff --git a/nuttx/drivers/mtd/Kconfig b/nuttx/drivers/mtd/Kconfig
index 310f494d8..4754fbeb7 100644
--- a/nuttx/drivers/mtd/Kconfig
+++ b/nuttx/drivers/mtd/Kconfig
@@ -64,13 +64,6 @@ config RAMMTD_FLASHSIM
 		RAMMTD_FLASHSIM will add some extra logic to improve the level of
 		FLASH simulation.
 
-config RAMMTD_SMART
-	bool "SMART block driver support in the RAM MTD driver"
-	default n
-	---help---
-		Builds in additional ioctl and interface code to support the
-		SMART block driver / filesystem.
-
 endif
 
 config MTD_AT24XX
@@ -139,30 +132,14 @@ config M25P_MEMORY_TYPE
 	---help---
 		The memory type for M25 "P" series is 0x20, but the driver also supports "F" series
 		devices, such as the EON EN25F80 part which adds a 4K sector erase capability.  The
-		ID for "F" series parts from EON is 0x31.
-
-config M25P_SUBSECTOR_ERASE
-	bool "Sub-Sector Erase"
-	default n
-	---help---
-		Some devices (such as the EON EN25F80) support a smaller erase block
-		size (4K vs 64K).  This option enables support for sub-sector erase.
-		The SMART file system can take advantage of this option if it is enabled.
-
-config M25P_BYTEWRITE
-	bool "Enable ByteWrite ioctl support"
-	default n
-	---help---
-		The M25P series of devices allow writing to a page with less than a full-page
-		size of data.  In this case, only the written bytes are updated without affecting
-		the other bytes in the page.  The SMART FS requires this option for proper operation.
+		memory type for "F" series parts from EON is 0x31.  The 4K sector erase size will
+		automatically be enabled when filessytems that can use it are enabled, such as SMART.
 
 endif
 
 config MTD_SMART
 	bool "Sector Mapped Allocation for Really Tiny (SMART) Flash support"
 	default y
-	select M25P_BYTEWRITE
 	---help---
 		The MP25x series of Flash devices are typically very small and have a very large
 		erase block size.  This causes issues with the standard Flash Translation Layer
diff --git a/nuttx/drivers/mtd/m25px.c b/nuttx/drivers/mtd/m25px.c
index bfe21a7dd..17f7a0672 100644
--- a/nuttx/drivers/mtd/m25px.c
+++ b/nuttx/drivers/mtd/m25px.c
@@ -3,7 +3,7 @@
  * Driver for SPI-based M25P1 (128Kbit),  M25P64 (32Mbit), M25P64 (64Mbit), and
  * M25P128 (128Mbit) FLASH (and compatible).
  *
- *   Copyright (C) 2009-2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009-2011, 2013 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -114,6 +114,7 @@
 #define M25P_EN25F80_PAGE_SHIFT   8     /* Page size 1 << 8 = 256 */
 #define M25P_EN25F80_NPAGES       4096
 #define M25P_EN25F80_SUBSECT_SHIFT 12   /* Sub-Sector size 1 << 12 = 4,096 */
+#define M25P_EN25F80_NSUBSECTORS  256
 
 /*  M25P32 capacity is 4,194,304 bytes:
  *  (64 sectors) * (65,536 bytes per sector)
@@ -203,7 +204,7 @@ struct m25p_dev_s
   uint8_t  pageshift;        /* 8 */
   uint16_t nsectors;         /* 128 or 64 */
   uint32_t npages;           /* 32,768 or 65,536 */
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
+#ifdef CONFIG_MTD_SMART
   uint8_t  subsectorshift;   /* 0, 12 or 13 (4K or 8K) */
 #endif
 };
@@ -219,13 +220,10 @@ static inline void m25p_unlock(FAR struct spi_dev_s *dev);
 static inline int m25p_readid(struct m25p_dev_s *priv);
 static void m25p_waitwritecomplete(struct m25p_dev_s *priv);
 static void m25p_writeenable(struct m25p_dev_s *priv);
-static inline void m25p_sectorerase(struct m25p_dev_s *priv, off_t offset);
+static inline void m25p_sectorerase(struct m25p_dev_s *priv, off_t offset, uint8_t type);
 static inline int  m25p_bulkerase(struct m25p_dev_s *priv);
 static inline void m25p_pagewrite(struct m25p_dev_s *priv, FAR const uint8_t *buffer,
                                   off_t offset);
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
-static inline void m25p_subsectorerase(struct m25p_dev_s *priv, off_t offset);
-#endif
 
 /* MTD driver methods */
 
@@ -236,6 +234,10 @@ static ssize_t m25p_bwrite(FAR struct mtd_dev_s *dev, off_t startblock,
                            size_t nblocks, FAR const uint8_t *buf);
 static ssize_t m25p_read(FAR struct mtd_dev_s *dev, off_t offset, size_t nbytes,
                          FAR uint8_t *buffer);
+#ifdef CONFIG_MTD_BYTE_WRITE
+static ssize_t m25p_write(FAR struct mtd_dev_s *dev, off_t offset, size_t nbytes,
+                         FAR const uint8_t *buffer);
+#endif
 static int m25p_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg);
 
 /************************************************************************************
@@ -320,7 +322,7 @@ static inline int m25p_readid(struct m25p_dev_s *priv)
     {
       /* Okay.. is it a FLASH capacity that we understand? */
 
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
+#ifdef CONFIG_MTD_SMART
       priv->subsectorshift = 0;
 #endif
 
@@ -338,11 +340,11 @@ static inline int m25p_readid(struct m25p_dev_s *priv)
         {
            /* Save the FLASH geometry */
 
-           priv->sectorshift    = M25P_EN25F80_SECTOR_SHIFT;
-           priv->nsectors       = M25P_EN25F80_NSECTORS;
            priv->pageshift      = M25P_EN25F80_PAGE_SHIFT;
            priv->npages         = M25P_EN25F80_NPAGES;
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
+           priv->sectorshift    = M25P_EN25F80_SECTOR_SHIFT;
+           priv->nsectors       = M25P_EN25F80_NSECTORS;
+#ifdef CONFIG_MTD_SMART
            priv->subsectorshift = M25P_EN25F80_SUBSECT_SHIFT;
 #endif
            return OK;
@@ -480,9 +482,20 @@ static void m25p_writeenable(struct m25p_dev_s *priv)
  * Name:  m25p_sectorerase
  ************************************************************************************/
 
-static inline void m25p_sectorerase(struct m25p_dev_s *priv, off_t sector)
+static void m25p_sectorerase(struct m25p_dev_s *priv, off_t sector, uint8_t type)
 {
-  off_t offset = sector << priv->sectorshift;
+  off_t offset;
+
+#ifdef CONFIG_MTD_SMART
+  if (priv->subsectorshift > 0)
+    {
+      offset = sector << priv->subsectorshift;
+    }
+  else
+#endif
+    {
+      offset = sector << priv->sectorshift;
+    }
 
   fvdbg("sector: %08lx\n", (long)sector);
 
@@ -502,55 +515,11 @@ static inline void m25p_sectorerase(struct m25p_dev_s *priv, off_t sector)
 
   SPI_SELECT(priv->dev, SPIDEV_FLASH, true);
 
-  /* Send the "Sector Erase (SE)" instruction */
-
-  (void)SPI_SEND(priv->dev, M25P_SE);
-
-  /* Send the sector offset high byte first.  For all of the supported
-   * parts, the sector number is completely contained in the first byte
-   * and the values used in the following two bytes don't really matter.
-   */
-
-  (void)SPI_SEND(priv->dev, (offset >> 16) & 0xff);
-  (void)SPI_SEND(priv->dev, (offset >> 8) & 0xff);
-  (void)SPI_SEND(priv->dev, offset & 0xff);
-
-  /* Deselect the FLASH */
-
-  SPI_SELECT(priv->dev, SPIDEV_FLASH, false);
-  fvdbg("Erased\n");
-}
-
-/************************************************************************************
- * Name:  m25p_subsectorerase
- ************************************************************************************/
-
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
-static inline void m25p_subsectorerase(struct m25p_dev_s *priv, off_t subsector)
-{
-  off_t offset = subsector << priv->subsectorshift;
-
-  fvdbg("subsector: %9lx\n", (long)subsector);
-
-  /* Wait for any preceding write to complete.  We could simplify things by
-   * perform this wait at the end of each write operation (rather than at
-   * the beginning of ALL operations), but have the wait first will slightly
-   * improve performance.
+  /* Send the "Sector Erase (SE)" or Sub-Sector Erase (SSE) instruction
+   * that was passed in as the erase type.
    */
 
-  m25p_waitwritecomplete(priv);
-
-  /* Send write enable instruction */
-
-  m25p_writeenable(priv);
-
-  /* Select this FLASH part */
-
-  SPI_SELECT(priv->dev, SPIDEV_FLASH, true);
-
-  /* Send the "Sub-Sector Erase (SSE)" instruction */
-
-  (void)SPI_SEND(priv->dev, M25P_SSE);
+  (void)SPI_SEND(priv->dev, type);
 
   /* Send the sector offset high byte first.  For all of the supported
    * parts, the sector number is completely contained in the first byte
@@ -566,7 +535,6 @@ static inline void m25p_subsectorerase(struct m25p_dev_s *priv, off_t subsector)
   SPI_SELECT(priv->dev, SPIDEV_FLASH, false);
   fvdbg("Erased\n");
 }
-#endif
 
 /************************************************************************************
  * Name:  m25p_bulkerase
@@ -654,7 +622,7 @@ static inline void m25p_pagewrite(struct m25p_dev_s *priv, FAR const uint8_t *bu
  * Name:  m25p_bytewrite
  ************************************************************************************/
 
-#ifdef CONFIG_M25P_BYTEWRITE
+#ifdef CONFIG_MTD_BYTE_WRITE
 static inline void m25p_bytewrite(struct m25p_dev_s *priv, FAR const uint8_t *buffer,
                                   off_t offset, uint16_t count)
 {
@@ -711,13 +679,55 @@ static int m25p_erase(FAR struct mtd_dev_s *dev, off_t startblock, size_t nblock
   /* Lock access to the SPI bus until we complete the erase */
 
   m25p_lock(priv->dev);
-  while (blocksleft-- > 0)
+  while (blocksleft > 0)
     {
-      /* Erase each sector */
+#ifdef CONFIG_MTD_SMART
+      size_t sectorboundry;
+      size_t blkper;
+
+      /* If we have a smaller erase size, then we will find as many full
+       * sector erase blocks as possible to speed up the process instead of
+       * erasing everything in smaller chunks.
+       */
+
+      if (priv->subsectorshift > 0)
+        {
+          blkper = 1 << (priv->sectorshift - priv->subsectorshift);
+          sectorboundry = (startblock + blkper - 1) / blkper;
+          sectorboundry *= blkper;
 
-      m25p_sectorerase(priv, startblock);
+          /* If we are on a sector boundry and have at least a full sector
+           * of blocks left to erase, then we can do a full sector erase.
+           */
+
+          if (startblock == sectorboundry && blocksleft >= blkper)
+            {
+              /* Do a full sector erase */
+
+              m25p_sectorerase(priv, startblock / blkper, M25P_SE);
+              startblock += blkper;
+              blocksleft -= blkper;
+              continue;
+            }
+          else
+            {
+              /* Just do a sub-sector erase */
+
+              m25p_sectorerase(priv, startblock, M25P_SSE);
+              startblock++;
+              blocksleft--;
+              continue;
+            }
+        }
+#endif
+
+      /* Not using sub-sector erase.  Erase each full sector */
+
+      m25p_sectorerase(priv, startblock, M25P_SE);
       startblock++;
+      blocksleft--;
     }
+
   m25p_unlock(priv->dev);
   return (int)nblocks;
 }
@@ -741,6 +751,7 @@ static ssize_t m25p_bread(FAR struct mtd_dev_s *dev, off_t startblock, size_t nb
     {
         return nbytes >> priv->pageshift;
     }
+
   return (int)nbytes;
 }
 
@@ -766,8 +777,8 @@ static ssize_t m25p_bwrite(FAR struct mtd_dev_s *dev, off_t startblock, size_t n
       buffer += pagesize;
       startblock++;
    }
-  m25p_unlock(priv->dev);
 
+  m25p_unlock(priv->dev);
   return nblocks;
 }
 
@@ -818,6 +829,78 @@ static ssize_t m25p_read(FAR struct mtd_dev_s *dev, off_t offset, size_t nbytes,
 }
 
 /************************************************************************************
+ * Name: m25p_write
+ ************************************************************************************/
+
+#ifdef CONFIG_MTD_BYTE_WRITE
+static ssize_t m25p_write(FAR struct mtd_dev_s *dev, off_t offset, size_t nbytes,
+                         FAR const uint8_t *buffer)
+{
+  FAR struct m25p_dev_s *priv = (FAR struct m25p_dev_s *)dev;
+  int    startpage;
+  int    endpage;
+  int    count;
+  int    index;
+  int    pagesize;
+  int    bytestowrite;
+
+  fvdbg("offset: %08lx nbytes: %d\n", (long)offset, (int)nbytes);
+
+  /* We must test if the offset + count crosses one or more pages
+   * and perform individual writes.  The devices can only write in
+   * page increments.
+   */
+
+  startpage = offset / (1 << priv->pageshift);
+  endpage = (offset + nbytes) / (1 << priv->pageshift);
+
+  if (startpage == endpage)
+    {
+      /* All bytes within one programmable page.  Just do the write. */
+
+      m25p_bytewrite(priv, buffer, offset, nbytes);
+    }
+  else
+    {
+      /* Write the 1st partial-page */
+
+      count = nbytes;
+      pagesize = (1 << priv->pageshift);
+      bytestowrite = pagesize - (offset & (pagesize-1));
+      m25p_bytewrite(priv, buffer, offset, bytestowrite);
+
+      /* Update offset and count */
+
+      offset += bytestowrite;
+      count -=  bytestowrite;
+      index = bytestowrite;
+
+      /* Write full pages */
+
+      while (count >= pagesize)
+        {
+          m25p_bytewrite(priv, &buffer[index], offset, pagesize);
+
+          /* Update offset and count */
+
+          offset += pagesize;
+          count -= pagesize;
+          index += pagesize;
+        }
+
+      /* Now write any partial page at the end */
+
+      if (count > 0)
+        {
+          m25p_bytewrite(priv, &buffer[index], offset, count);
+        }
+    }
+
+  return nbytes;
+}
+#endif /* CONFIG_MTD_BYTE_WRITE */
+
+/************************************************************************************
  * Name: m25p_ioctl
  ************************************************************************************/
 
@@ -844,15 +927,22 @@ static int m25p_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg)
                * appear so.
                */
 
-              geo->blocksize     = (1 << priv->pageshift);
-              geo->erasesize     = (1 << priv->sectorshift);
-              geo->neraseblocks  = priv->nsectors;
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
-              geo->subsectorsize = (1 << priv->subsectorshift);
-              geo->nsubsectors   = priv->nsectors * (1 << (priv->sectorshift -
-                                   priv->subsectorshift));
+              geo->blocksize = (1 << priv->pageshift);
+#ifdef CONFIG_MTD_SMART
+              if (priv->subsectorshift > 0)
+                {
+                  geo->erasesize    = (1 << priv->subsectorshift);
+                  geo->neraseblocks = priv->nsectors * (1 << (priv->sectorshift -
+                              priv->subsectorshift));
+                }
+              else
 #endif
-              ret                = OK;
+                {
+                  geo->erasesize    = (1 << priv->sectorshift);
+                  geo->neraseblocks = priv->nsectors;
+                }
+
+              ret = OK;
 
               fvdbg("blocksize: %d erasesize: %d neraseblocks: %d\n",
                     geo->blocksize, geo->erasesize, geo->neraseblocks);
@@ -870,97 +960,6 @@ static int m25p_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg)
         }
         break;
 
-#ifdef CONFIG_FS_SMARTFS
-      case MTDIOC_GETCAPS:
-        {
-          ret = 0;
-#ifdef CONFIG_M25P_BYTEWRITE
-          ret |= MTDIOC_CAPS_BYTEWRITE;
-#endif
-
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
-          ret |= MTDIOC_CAPS_SECTERASE;
-#endif
-          break;
-        }
-#endif /* CONFIG_FS_SMARTFS */
-
-#ifdef CONFIG_M25P_SUBSECTOR_ERASE
-      case MTDIOC_SECTERASE:
-        {
-          m25p_subsectorerase(priv, (off_t) arg);
-          ret = OK;
-          break;
-        }
-#endif
-
-#ifdef CONFIG_M25P_BYTEWRITE
-      case MTDIOC_BYTEWRITE:
-        {
-          struct mtd_byte_write_s *bytewrite = (struct mtd_byte_write_s *) arg;
-          int    startpage;
-          int    endpage;
-          int    count;
-          int    index;
-          int    pagesize;
-          int    bytestowrite;
-          size_t offset;
-
-          /* We must test if the offset + count crosses one or more pages
-           * and perform individual writes.  The devices can only write in
-           * page increments.
-           */
-
-          startpage = bytewrite->offset / (1 << priv->pageshift);
-          endpage = (bytewrite->offset + bytewrite->count) / (1 << priv->pageshift);
-
-          if (startpage == endpage)
-            {
-              m25p_bytewrite(priv, bytewrite->buffer, bytewrite->offset,
-                             bytewrite->count);
-            }
-          else
-            {
-              /* Write the 1st partial-page */
-
-              count = bytewrite->count;
-              pagesize = (1 << priv->pageshift);
-              offset = bytewrite->offset;
-              bytestowrite = pagesize - (bytewrite->offset & (pagesize-1));
-              m25p_bytewrite(priv, bytewrite->buffer, offset, bytestowrite);
-
-              /* Update offset and count */
-
-              offset += bytestowrite;
-              count -=  bytestowrite;
-              index = bytestowrite;
-
-              /* Write full pages */
-
-              while (count >= pagesize)
-                {
-                  m25p_bytewrite(priv, &bytewrite->buffer[index], offset, pagesize);
-
-                  /* Update offset and count */
-
-                  offset += pagesize;
-                  count -= pagesize;
-                  index += pagesize;
-                }
-
-              /* Now write any partial page at the end */
-
-              if (count > 0)
-                {
-                  m25p_bytewrite(priv, &bytewrite->buffer[index], offset, count);
-                }
-            }
-
-          ret = OK;
-          break;
-        }
-#endif
-
       case MTDIOC_XIPBASE:
       default:
         ret = -ENOTTY; /* Bad command */
@@ -1010,6 +1009,9 @@ FAR struct mtd_dev_s *m25p_initialize(FAR struct spi_dev_s *dev)
       priv->mtd.bread  = m25p_bread;
       priv->mtd.bwrite = m25p_bwrite;
       priv->mtd.read   = m25p_read;
+#ifdef CONFIG_MTD_BYTE_WRITE
+      priv->mtd.write  = m25p_write;
+#endif
       priv->mtd.ioctl  = m25p_ioctl;
       priv->dev        = dev;
 
diff --git a/nuttx/drivers/mtd/mtd_partition.c b/nuttx/drivers/mtd/mtd_partition.c
index 1bff0af9c..699a2fa5a 100644
--- a/nuttx/drivers/mtd/mtd_partition.c
+++ b/nuttx/drivers/mtd/mtd_partition.c
@@ -137,7 +137,7 @@ static bool part_bytecheck(FAR struct mtd_partition_s *priv, off_t byoff)
 
   erasesize = priv->blocksize * priv->blkpererase;
   readend   = (byoff + erasesize - 1) / erasesize;
-  return readend <  priv->neraseblocks;
+  return readend <= priv->neraseblocks;
 }
 
 /****************************************************************************
@@ -410,6 +410,12 @@ static int part_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg)
  *   sector count (where the size of a sector is provided the by parent MTD
  *   driver).
  *
+ *   NOTE: Since there may be a number of MTD partition drivers operating on
+ *   the same, underlying FLASH driver, that FLASH driver must be capable
+ *   of enforcing mutually exclusive access to the FLASH device.  Without
+ *   partitions, that mutual exclusion would be provided by the file system
+ *   above the FLASH driver.
+ *
  ****************************************************************************/
 
 FAR struct mtd_dev_s *mtd_partition(FAR struct mtd_dev_s *mtd, off_t firstblock,
@@ -483,6 +489,9 @@ FAR struct mtd_dev_s *mtd_partition(FAR struct mtd_dev_s *mtd, off_t firstblock,
   part->child.bwrite = part_bwrite;
   part->child.read   = mtd->read ? part_read : NULL;
   part->child.ioctl  = part_ioctl;
+#ifdef CONFIG_MTD_BYTE_WRITE
+  part->child.write  = mtd->write ? part_write : NULL;
+#endif
 
   part->parent       = mtd;
   part->firstblock   = erasestart * blkpererase;
diff --git a/nuttx/drivers/mtd/rammtd.c b/nuttx/drivers/mtd/rammtd.c
index 461cd7d99..137f91f73 100644
--- a/nuttx/drivers/mtd/rammtd.c
+++ b/nuttx/drivers/mtd/rammtd.c
@@ -228,7 +228,7 @@ static int ram_erase(FAR struct mtd_dev_s *dev, off_t startblock, size_t nblocks
  * Name: ram_readbytes
  ****************************************************************************/
 
-#ifdef CONFIG_RAMMTD_SMART
+#ifdef CONFIG_MTD_SMART
 static ssize_t ram_read_bytes(FAR struct mtd_dev_s *dev, off_t offset,
         size_t nbytes, FAR uint8_t *buf)
 {
@@ -329,6 +329,34 @@ static ssize_t ram_bwrite(FAR struct mtd_dev_s *dev, off_t startblock,
 }
 
 /****************************************************************************
+ * Name: ram_bytewrite
+ ****************************************************************************/
+
+#ifdef CONFIG_MTD_BYTE_WRITE
+static ssize_t ram_bytewrite(FAR struct mtd_dev_s *dev, off_t offset,
+                          size_t nbytes, FAR const uint8_t *buf)
+{
+  FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
+  off_t maxaddr;
+
+  DEBUGASSERT(dev && buf);
+
+  /* Don't let the write exceed the size of the ram buffer */
+
+  maxaddr = priv->nblocks * CONFIG_RAMMTD_ERASESIZE;
+  if (offset + nbytes > maxaddr)
+    {
+      return 0;
+    }
+
+  /* Then write the data to RAM */
+
+  ram_write(&priv->start[offset], buf, nbytes);
+  return nbytes;
+}
+#endif
+
+/****************************************************************************
  * Name: ram_ioctl
  ****************************************************************************/
 
@@ -380,24 +408,6 @@ static int ram_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg)
         }
         break;
 
-#ifdef CONFIG_RAMMTD_SMART
-      case MTDIOC_GETCAPS:
-        {
-          ret = MTDIOC_CAPS_BYTEWRITE;
-          break;
-        }
-
-      case MTDIOC_BYTEWRITE:
-        {
-          struct mtd_byte_write_s *bytewrite = (struct mtd_byte_write_s *) arg;
-
-          ram_write(&priv->start[bytewrite->offset], bytewrite->buffer,
-                  bytewrite->count);
-          ret = OK;
-          break;
-        }
-#endif
-
       default:
         ret = -ENOTTY; /* Bad command */
         break;
@@ -454,9 +464,14 @@ FAR struct mtd_dev_s *rammtd_initialize(FAR uint8_t *start, size_t size)
   priv->mtd.bwrite = ram_bwrite;
   priv->mtd.ioctl  = ram_ioctl;
   priv->mtd.erase  = ram_erase;
+#ifdef CONFIG_MTD_BYTE_WRITE
+  priv->mtd.write  = ram_bytewrite;
+#endif
 
-#ifdef CONFIG_RAMMTD_SMART
+#ifdef CONFIG_MTD_SMART
   priv->mtd.read   = ram_read_bytes;
+#else
+  priv->mtd.read   = NULL;
 #endif
 
   priv->start      = start;
diff --git a/nuttx/drivers/mtd/smart.c b/nuttx/drivers/mtd/smart.c
index 9de557b5f..35a367e5b 100644
--- a/nuttx/drivers/mtd/smart.c
+++ b/nuttx/drivers/mtd/smart.c
@@ -97,7 +97,7 @@
 
 #define SMART_FMT_VERSION           1
 
-#define SMART_FIRST_ALLOC_SECTOR    16      /* First logical sector number we will
+#define SMART_FIRST_ALLOC_SECTOR    12      /* First logical sector number we will
                                              * use for assignment of requested Alloc
                                              * sectors.  All enries below this are
                                              * reserved (some for root dir entries,
@@ -134,6 +134,7 @@ struct smart_struct_s
   FAR uint8_t          *releasecount;     /* Count of released sectors per erase block */
   FAR uint8_t          *freecount;        /* Count of free sectors per erase block */
   FAR char             *rwbuffer;         /* Our sector read/write buffer */
+  const FAR char       *partname;         /* Optional partition name */
   uint8_t               formatversion;    /* Format version on the device */
   uint8_t               formatstatus;     /* Indicates the status of the device format */
   uint8_t               namesize;         /* Length of filenames on this device */
@@ -471,49 +472,21 @@ static int smart_setsectorsize(struct smart_struct_s *dev, uint16_t size)
 {
   uint32_t  erasesize;
   uint32_t  totalsectors;
-  int       ret;
 
-  /* Check if the device supports sub-sector erase regions. If it does, then
-   * use the sub-sector erase size instead of the larger erase size to
-   * provide finer granularity.
-   */
+  /* Validate the size isn't zero so we don't divide by zero below */
 
-#ifdef CONFIG_MTD_SUBSECTOR_ERASE
-  ret = MTD_IOCTL(dev->mtd, MTDIOC_GETCAPS, 0);
-  if (ret >= 0)
+  if (size == 0)
     {
-      /* The block device supports the GETCAPS ioctl. Now check if sub-sector
-       * erase is supported.
-       */
-
-      if (!(ret & MTDIOC_CAPS_SECTERASE))
-        {
-          /* Ensure the subsector size is zero */
-          dev->geo.subsectorsize = 0;
-          dev->geo.nsubsectors = 0;
-        }
+      size = CONFIG_MTD_SMART_SECTOR_SIZE;
     }
 
-  /* Now calculate the variables */
-
-  if (dev->geo.subsectorsize != 0)
-    {
-      /* Use the sub-sector erase size */
-
-      erasesize = dev->geo.subsectorsize;
-      dev->neraseblocks = dev->geo.nsubsectors;
-    }
-  else
-#endif /* CONFIG_MTD_SUBSECTOR_ERASE */
-    {
-      erasesize = dev->geo.erasesize;
-      dev->neraseblocks = dev->geo.neraseblocks;
-    }
+  erasesize = dev->geo.erasesize;
+  dev->neraseblocks = dev->geo.neraseblocks;
 
   /* Most FLASH devices have erase size of 64K, but geo.erasesize is only
    * 16 bits, so it will be zero
    */
- 
+
   if (erasesize == 0)
     {
       erasesize = 65536;
@@ -569,6 +542,74 @@ static int smart_setsectorsize(struct smart_struct_s *dev, uint16_t size)
 }
 
 /****************************************************************************
+ * Name: smart_bytewrite
+ *
+ * Description: Writes a non-page size count of bytes to the underlying
+ *              MTD device.  If the MTD driver supports a direct impl of
+ *              write, then it uses it, otherwise it does a read-modify-write
+ *              and depends on the architecture of the flash to only program
+ *              bits that acutally changed.
+ *
+ ****************************************************************************/
+
+static ssize_t smart_bytewrite(struct smart_struct_s *dev, size_t offset,
+        int nbytes, const uint8_t *buffer)
+{
+  ssize_t       ret;
+
+#ifdef CONFIG_MTD_BYTE_WRITE
+  /* Check if the underlying MTD device supports write */
+
+  if (dev->mtd->write != NULL)
+    {
+      /* Use the MTD's write method to write individual bytes */
+
+      ret = dev->mtd->write(dev->mtd, offset, nbytes, buffer);
+    }
+  else
+#endif
+    {
+      /* Perform block-based read-modify-write */
+
+      uint16_t  startblock;
+      uint16_t  nblocks;
+
+      /* First calculate the start block and number of blocks affected */
+
+      startblock = offset / dev->geo.blocksize;
+      nblocks = (nbytes + dev->geo.blocksize-1) / dev->geo.blocksize;
+      DEBUGASSERT(nblocks <= dev->mtdBlksPerSector);
+
+      /* Do a block read */
+
+      ret = MTD_BREAD(dev->mtd, startblock, nblocks, (uint8_t *) dev->rwbuffer);
+      if (ret < 0)
+        {
+          fdbg("Error %d reading from device\n", -ret);
+          goto errout;
+        }
+
+      /* Modify the data */
+
+      memcpy(&dev->rwbuffer[offset - startblock * dev->geo.blocksize], buffer, nbytes);
+
+      /* Write the data back to the device */
+
+      ret = MTD_BWRITE(dev->mtd, startblock, nblocks, (uint8_t *) dev->rwbuffer);
+      if (ret < 0)
+        {
+          fdbg("Error %d writing to device\n", -ret);
+          goto errout;
+        }
+    }
+
+  ret = nbytes;
+
+errout:
+  return ret;
+}
+
+/****************************************************************************
  * Name: smart_scan
  *
  * Description: Performs a scan of the MTD device searching for format
@@ -581,17 +622,17 @@ static int smart_scan(struct smart_struct_s *dev)
 {
   int       sector;
   int       ret;
-  int       x;
+  int       offset;
   uint16_t  totalsectors;
   uint16_t  sectorsize;
   uint16_t  logicalsector;
   uint16_t  seq1;
   uint16_t  seq2;
-  char      devname[18];
   size_t    readaddress;
   struct    smart_sect_header_s header;
-  struct    mtd_byte_write_s bytewrite;
 #ifdef CONFIG_SMARTFS_MULTI_ROOT_DIRS
+  int       x;
+  char      devname[22];
   struct    smart_multiroot_device_s *rootdirdev;
 #endif
 
@@ -675,7 +716,7 @@ static int smart_scan(struct smart_struct_s *dev)
         }
 #endif
 
-      /* Test if this sector has been commited */
+      /* Test if this sector has been committed */
 
       if ((header.status & SMART_STATUS_COMMITTED) ==
               (CONFIG_SMARTFS_ERASEDSTATE & SMART_STATUS_COMMITTED))
@@ -763,7 +804,16 @@ static int smart_scan(struct smart_struct_s *dev)
 
           for (x = 1; x < dev->rootdirentries; x++)
             {
-              snprintf(devname, 18, "/dev/smart%dd%d", dev->minor, x + 1);
+              if (dev->partname != NULL)
+                {
+                  snprintf(dev->rwbuffer, sizeof(devname), "/dev/smart%d%s%d",
+                          dev->minor, dev->partname, x+1);
+                }
+              else
+                {
+                  snprintf(devname, sizeof(devname), "/dev/smart%dd%d", dev->minor,
+                           x + 1);
+                }
 
               /* Inode private data is a reference to a struct containing
                * the SMART device structure and the root directory number.
@@ -792,9 +842,9 @@ static int smart_scan(struct smart_struct_s *dev)
 
       /* Test for duplicate logical sectors on the device */
 
-      if (dev->sMap[logicalsector] != -1)
+      if (dev->sMap[logicalsector] != 0xFFFF)
         {
-          /* TODO: Uh-oh, we found more than 1 physical sector claiming to be
+          /* Uh-oh, we found more than 1 physical sector claiming to be
            * the * same logical sector.  Use the sequence number information
            * to resolve who wins.
            */
@@ -853,10 +903,13 @@ static int smart_scan(struct smart_struct_s *dev)
 #else
           header.status |= SMART_STATUS_RELEASED;
 #endif
-          bytewrite.offset = readaddress + offsetof(struct smart_sect_header_s, status);
-          bytewrite.count = 1;
-          bytewrite.buffer = &header.status;
-          ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
+          offset = readaddress + offsetof(struct smart_sect_header_s, status);
+          ret = smart_bytewrite(dev, offset, 1, &header.status);
+          if (ret < 0)
+            {
+              fdbg("Error %d releasing duplicate sector\n", -ret);
+              goto err_out;
+            }
         }
 
       /* Update the logical to physical sector map */
@@ -886,9 +939,11 @@ err_out:
 
 #ifdef CONFIG_SMARTFS_MULTI_ROOT_DIRS
 static inline int smart_getformat(struct smart_struct_s *dev,
-        struct smart_format_s *fmt, uint8_t rootdirnum)
+                                  struct smart_format_s *fmt,
+                                  uint8_t rootdirnum)
 #else
-static inline int smart_getformat(struct smart_struct_s *dev, struct smart_format_s *fmt)
+static inline int smart_getformat(struct smart_struct_s *dev,
+                                  struct smart_format_s *fmt)
 #endif
 {
   int ret;
@@ -914,8 +969,6 @@ static inline int smart_getformat(struct smart_struct_s *dev, struct smart_forma
         }
     }
 
-  /* TODO: Determine if the underlying MTD device supports bytewrite */
-
   /* Now fill in the structure */
 
   if (dev->formatstatus == SMART_FMT_STAT_FORMATTED)
@@ -978,7 +1031,7 @@ static inline int smart_llformat(struct smart_struct_s *dev, unsigned long arg)
   /* Erase the MTD device */
 
   ret = MTD_IOCTL(dev->mtd, MTDIOC_BULKERASE, 0);
-  if (ret != OK)
+  if (ret < 0)
     {
       return ret;
     }
@@ -1180,8 +1233,9 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
   bool      collect = TRUE;
   int       x;
   int       ret;
+  size_t    offset;
   struct    smart_sect_header_s *header;
-  struct    mtd_byte_write_s bytewrite;
+  uint8_t   newstatus;
 
   while (collect)
     {
@@ -1196,8 +1250,6 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
         {
           releasedsectors += dev->releasecount[x];
           if (dev->releasecount[x] > releasemax)
-//          if (dev->releasecount[x] > releasemax &&
-//              dev->freecount[x] < (dev->sectorsPerBlk >> 1))
             {
               releasemax = dev->releasecount[x];
               collectblock = x;
@@ -1205,7 +1257,8 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
         }
 
       /* Test if the released sectors count is greater than the
-       * free sectors.  If it is, then we will do garbage collection */
+       * free sectors.  If it is, then we will do garbage collection.
+       */
 
       if (releasedsectors > dev->freesectors)
         collect = TRUE;
@@ -1238,7 +1291,8 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
 
           /* Perform collection on block with the most released sectors.
            * First mark the block as having no free sectors so we don't
-           * try to move sectors into the block we are trying to erase. */
+           * try to move sectors into the block we are trying to erase.
+           */
 
           dev->freecount[collectblock] = 0;
 
@@ -1267,7 +1321,8 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
                    (CONFIG_SMARTFS_ERASEDSTATE & SMART_STATUS_RELEASED)))
                 {
                   /* This sector doesn't have live data (free or released).
-                   * just continue to the next sector and don't move it. */
+                   * just continue to the next sector and don't move it.
+                   */
 
                   continue;
                 }
@@ -1304,27 +1359,35 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
 
               /* Commit the sector */
 
-              bytewrite.offset = newsector * dev->mtdBlksPerSector * dev->geo.blocksize +
+              offset = newsector * dev->mtdBlksPerSector * dev->geo.blocksize +
                   offsetof(struct smart_sect_header_s, status);
 #if CONFIG_SMARTFS_ERASEDSTATE == 0xFF
-              header->status &= ~SMART_STATUS_COMMITTED;
+              newstatus = header->status & ~SMART_STATUS_COMMITTED;
 #else
-              header->status |= SMART_STATUS_COMMITTED;
+              newstatus = header->status | SMART_STATUS_COMMITTED;
 #endif
-              bytewrite.count = 1;
-              bytewrite.buffer = &header->status;
-              ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
+              ret = smart_bytewrite(dev, offset, 1, &newstatus);
+              if (ret < 0)
+                {
+                  fdbg("Error %d committing new sector %d\n" -ret, newsector);
+                  goto errout;
+                }
 
               /* Release the old physical sector */
 
 #if CONFIG_SMARTFS_ERASEDSTATE == 0xFF
-              header->status &= ~SMART_STATUS_RELEASED;
+              newstatus = header->status & ~SMART_STATUS_RELEASED;
 #else
-              header->status |= SMART_STATUS_RELEASED;
+              newstatus = header->status | SMART_STATUS_RELEASED;
 #endif
-              bytewrite.offset = x * dev->mtdBlksPerSector * dev->geo.blocksize +
+              offset = x * dev->mtdBlksPerSector * dev->geo.blocksize +
                   offsetof(struct smart_sect_header_s, status);
-              ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
+              ret = smart_bytewrite(dev, offset, 1, &newstatus);
+              if (ret < 0)
+                {
+                  fdbg("Error %d releasing old sector %d\n" -ret, x);
+                  goto errout;
+                }
 
               /* Update the variables */
 
@@ -1334,17 +1397,7 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
 
           /* Now erase the erase block */
 
-#ifdef CONFIG_MTD_SUBSECTOR_ERASE
-          if (dev->geo.subsectorsize != 0)
-            {
-              /* Perform a sub-sector erase */
-              MTD_IOCTL(dev->mtd, MTDIOC_SECTERASE, collectblock);
-            }
-          else
-#endif
-            {
-              MTD_ERASE(dev->mtd, collectblock, 1);
-            }
+          MTD_ERASE(dev->mtd, collectblock, 1);
 
           dev->freesectors += dev->releasecount[collectblock];
           dev->freecount[collectblock] = dev->sectorsPerBlk;
@@ -1357,18 +1410,19 @@ static int smart_garbagecollect(struct smart_struct_s *dev)
               /* Set the sector size in the 1st header */
 
               uint8_t sectsize = dev->sectorsize >> 7;
-              header = (struct smart_sect_header_s *) dev->rwbuffer;
 #if ( CONFIG_SMARTFS_ERASEDSTATE == 0xFF )
-              header->status = (uint8_t) ~SMART_STATUS_SIZEBITS | sectsize;
+              newstatus = (uint8_t) ~SMART_STATUS_SIZEBITS | sectsize;
 #else
-              header->status = (uint8_t) sectsize;
+              newstatus = (uint8_t) sectsize;
 #endif
               /* Write the sector size to the device */
 
-              bytewrite.offset = offsetof(struct smart_sect_header_s, status);
-              bytewrite.count = 1;
-              bytewrite.buffer = &header->status;
-              MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
+              offset = offsetof(struct smart_sect_header_s, status);
+              ret = smart_bytewrite(dev, offset, 1, &newstatus);
+              if (ret < 0)
+                {
+                  fdbg("Error %d setting sector 0 size\n", -ret);
+                }
             }
 
           /* Update the block aging information in the format signature sector */
@@ -1402,15 +1456,15 @@ errout:
 #ifdef CONFIG_FS_WRITABLE
 static inline int smart_writesector(struct smart_struct_s *dev, unsigned long arg)
 {
-  int ret;
-  uint16_t x;
-  bool needsrelocate = FALSE;
-  uint16_t mtdblock;
-  uint16_t physsector;
-  struct smart_read_write_s *req;
-  struct smart_sect_header_s *header;
-  struct mtd_byte_write_s bytewrite;
-  uint8_t byte;
+  int       ret;
+  uint16_t  x;
+  bool      needsrelocate = FALSE;
+  uint16_t  mtdblock;
+  uint16_t  physsector;
+  struct    smart_read_write_s *req;
+  struct    smart_sect_header_s *header;
+  size_t    offset;
+  uint8_t   byte;
 
   fvdbg("Entry\n");
   req = (struct smart_read_write_s *) arg;
@@ -1515,16 +1569,14 @@ static inline int smart_writesector(struct smart_struct_s *dev, unsigned long ar
       /* Commit the new physical sector */
 
 #if CONFIG_SMARTFS_ERASEDSTATE == 0xFF
-      header->status &= ~SMART_STATUS_COMMITTED;
+      byte = header->status & ~SMART_STATUS_COMMITTED;
 #else
-      header->status |= SMART_STATUS_COMMITTED;
+      byte = header->status | SMART_STATUS_COMMITTED;
 #endif
-      bytewrite.offset = physsector * dev->mtdBlksPerSector *
-          dev->geo.blocksize + offsetof(struct smart_sect_header_s, status);
-      bytewrite.count = 1;
-      bytewrite.buffer = (uint8_t *) &header->status;
-      ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
-      if (ret != OK)
+      offset = physsector * dev->mtdBlksPerSector * dev->geo.blocksize +
+          offsetof(struct smart_sect_header_s, status);
+      ret = smart_bytewrite(dev, offset, 1, &byte);
+      if (ret != 1)
         {
           fvdbg("Error committing physical sector %d\n", physsector);
           ret = -EIO;
@@ -1534,13 +1586,13 @@ static inline int smart_writesector(struct smart_struct_s *dev, unsigned long ar
       /* Release the old physical sector */
 
 #if CONFIG_SMARTFS_ERASEDSTATE == 0xFF
-      header->status &= ~SMART_STATUS_RELEASED;
+      byte = header->status & ~SMART_STATUS_RELEASED;
 #else
-      header->status |= SMART_STATUS_RELEASED;
+      byte = header->status | SMART_STATUS_RELEASED;
 #endif
-      bytewrite.offset = mtdblock * dev->geo.blocksize +
+      offset = mtdblock * dev->geo.blocksize +
           offsetof(struct smart_sect_header_s, status);
-      ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
+      ret = smart_bytewrite(dev, offset, 1, &byte);
 
       /* Update releasecount for released sector and freecount for the
        * newly allocated physical sector. */
@@ -1564,11 +1616,9 @@ static inline int smart_writesector(struct smart_struct_s *dev, unsigned long ar
       /* Not relocated.  Just write the portion of the sector that needs
        * to be written. */
 
-      bytewrite.offset = mtdblock * dev->geo.blocksize +
+      offset = mtdblock * dev->geo.blocksize +
           sizeof(struct smart_sect_header_s) + req->offset;
-      bytewrite.count = req->count;
-      bytewrite.buffer = req->buffer;
-      ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
+      ret = smart_bytewrite(dev, offset, req->count, req->buffer);
     }
 
   ret = OK;
@@ -1743,9 +1793,8 @@ static inline int smart_allocsector(struct smart_struct_s *dev, unsigned long re
        * rescan and try again to "self heal" in case of a
        * bug in our code? */
 
-      fdbg("Couldn't find free sector when I expected too\n");
-
-      /* Unlock the mutex if we add one */
+      fdbg("No free logical sector numbers!  Free sectors = %d\n",
+              dev->freesectors);
 
       return -EIO;
     }
@@ -1827,7 +1876,7 @@ static inline int smart_freesector(struct smart_struct_s *dev, unsigned long
   uint16_t  physsector;
   uint16_t  block;
   struct    smart_sect_header_s  header;
-  struct    mtd_byte_write_s bytewrite;
+  size_t    offset;
 
   /* Check if the logical sector is within bounds */
 
@@ -1875,11 +1924,9 @@ static inline int smart_freesector(struct smart_struct_s *dev, unsigned long
 
   /* Write the status back to the device */
 
-  bytewrite.offset = readaddr + offsetof(struct smart_sect_header_s, status);
-  bytewrite.count = 1;
-  bytewrite.buffer = &header.status;
-  ret = MTD_IOCTL(dev->mtd, MTDIOC_BYTEWRITE, (unsigned long) &bytewrite);
-  if (ret != OK)
+  offset = readaddr + offsetof(struct smart_sect_header_s, status);
+  ret = smart_bytewrite(dev, offset, 1, &header.status);
+  if (ret != 1)
     {
       fdbg("Error updating physicl sector %d status\n", physsector);
       goto errout;
@@ -1900,15 +1947,7 @@ static inline int smart_freesector(struct smart_struct_s *dev, unsigned long
     {
       /* Erase the block */
 
-#ifdef CONFIG_MTD_SUBSECTOR_ERASE
-      if (dev->geo.subsectorsize != 0)
-        {
-          /* Perform a sub-sector erase */
-          MTD_IOCTL(dev->mtd, MTDIOC_SECTERASE, block);
-        }
-      else
-#endif
-        MTD_ERASE(dev->mtd, block, 1);
+      MTD_ERASE(dev->mtd, block, 1);
 
       dev->freesectors += dev->releasecount[block];
       dev->releasecount[block] = 0;
@@ -2050,7 +2089,7 @@ ok_out:
  *
  ****************************************************************************/
 
-int smart_initialize(int minor, FAR struct mtd_dev_s *mtd)
+int smart_initialize(int minor, FAR struct mtd_dev_s *mtd, const char *partname)
 {
   struct smart_struct_s *dev;
   int ret = -ENOMEM;
@@ -2084,10 +2123,6 @@ int smart_initialize(int minor, FAR struct mtd_dev_s *mtd)
 
       /* Set these to zero in case the device doesn't support them */
 
-#ifdef CONFIG_MTD_SUBSECTOR_ERASE
-      dev->geo.subsectorsize= 0;
-      dev->geo.nsubsectors  = 0;
-#endif
       ret = MTD_IOCTL(mtd, MTDIOC_GEOMETRY, (unsigned long)((uintptr_t)&dev->geo));
       if (ret < 0)
         {
@@ -2123,6 +2158,7 @@ int smart_initialize(int minor, FAR struct mtd_dev_s *mtd)
 
       dev->formatstatus = SMART_FMT_STAT_UNKNOWN;
       dev->namesize = CONFIG_SMARTFS_MAXNAMLEN;
+      dev->partname = partname;
 #ifdef CONFIG_SMARTFS_MULTI_ROOT_DIRS
       dev->minor = minor;
 #endif
@@ -2130,7 +2166,10 @@ int smart_initialize(int minor, FAR struct mtd_dev_s *mtd)
       /* Create a MTD block device name */
 
 #ifdef CONFIG_SMARTFS_MULTI_ROOT_DIRS
-      snprintf(dev->rwbuffer, 18, "/dev/smart%dd1", minor);
+      if (partname != NULL)
+        snprintf(dev->rwbuffer, 18, "/dev/smart%d%sd1", minor, partname);
+      else
+        snprintf(dev->rwbuffer, 18, "/dev/smart%dd1", minor);
 
       /* Inode private data is a reference to a struct containing
        * the SMART device structure and the root directory number.
@@ -2154,7 +2193,10 @@ int smart_initialize(int minor, FAR struct mtd_dev_s *mtd)
       ret = register_blockdriver(dev->rwbuffer, &g_bops, 0, rootdirdev);
 
 #else
-      snprintf(dev->rwbuffer, 18, "/dev/smart%d", minor);
+      if (partname != NULL)
+        snprintf(dev->rwbuffer, 18, "/dev/smart%d%s", minor, partname);
+      else
+        snprintf(dev->rwbuffer, 18, "/dev/smart%d", minor);
 
       /* Inode private data is a reference to the SMART device structure */
 
@@ -2167,6 +2209,7 @@ int smart_initialize(int minor, FAR struct mtd_dev_s *mtd)
           kfree(dev->sMap);
           kfree(dev->rwbuffer);
           kfree(dev);
+          goto errout;
         }
 
       /* Do a scan of the device */