Add an example to test MTD R/W buffering

7 files changed, 672 insertions, 2 deletions

diff --git a/apps/examples/Kconfig b/apps/examples/Kconfig
index bd602bbcc..3c1639923 100644
--- a/apps/examples/Kconfig
+++ b/apps/examples/Kconfig
@@ -26,6 +26,7 @@ source "$APPSDIR/examples/mm/Kconfig"
 source "$APPSDIR/examples/modbus/Kconfig"
 source "$APPSDIR/examples/mount/Kconfig"
 source "$APPSDIR/examples/mtdpart/Kconfig"
+source "$APPSDIR/examples/mtdrwb/Kconfig"
 source "$APPSDIR/examples/netpkt/Kconfig"
 source "$APPSDIR/examples/nettest/Kconfig"
 source "$APPSDIR/examples/nrf24l01_term/Kconfig"
diff --git a/apps/examples/Makefile b/apps/examples/Makefile
index f251518aa..815b410a3 100644
--- a/apps/examples/Makefile
+++ b/apps/examples/Makefile
@@ -39,7 +39,7 @@
 
 SUBDIRS  = adc buttons can cc3000 cpuhog cxxtest dhcpd discover elf
 SUBDIRS += flash_test ftpc ftpd hello helloxx hidkbd igmp i2schar json
-SUBDIRS += keypadtest lcdrw mm modbus mount mtdpart netpkt nettest
+SUBDIRS += keypadtest lcdrw mm modbus mount mtdpart mtdrwb netpkt nettest
 SUBDIRS += nrf24l01_term nsh null nx nxterm nxffs nxflat nxhello nximage
 SUBDIRS += nxlines nxtext ostest pashello pipe poll posix_spawn pwm qencoder
 SUBDIRS += random relays rgmp romfs sendmail serialblaster serloop serialrx
@@ -54,7 +54,7 @@ CNTXTDIRS = pwm
 
 ifeq ($(CONFIG_NSH_BUILTIN_APPS),y)
 CNTXTDIRS += adc can cc3000 cpuhog cxxtest dhcpd discover flash_test ftpd
-CNTXTDIRS += hello helloxx i2schar json keypadtestmodbus lcdrw mtdpart
+CNTXTDIRS += hello helloxx i2schar json keypadtestmodbus lcdrw mtdpart mtdrwb
 CNTXTDIRS += netpkt nettest nx nxhello nximage nxlines nxtext nrf24l01_term
 CNTXTDIRS += ostest random relays qencoder serialblasterslcd serialrx
 CNTXTDIRS += smart_test tcpecho telnetd tiff touchscreen usbterm watchdog
diff --git a/apps/examples/README.txt b/apps/examples/README.txt
index 09c155efc..a1d754ae1 100644
--- a/apps/examples/README.txt
+++ b/apps/examples/README.txt
@@ -661,6 +661,30 @@ examples/mtdpart
   * CONFIG_EXAMPLES_MTDPART_NEBLOCKS - This value gives the nubmer of erase
     blocks in MTD RAM device.
 
+examples/mtdrwb
+^^^^^^^^^^^^^^^^
+
+  This examples provides a simple test of MTD Read-Ahead/Write buffering
+  logic.
+
+  * CONFIG_EXAMPLES_MTDRWB - Enables the MTD R/W buffering test example
+  * CONFIG_EXAMPLES_MTDRWB_ARCHINIT - The default is to use the RAM MTD
+    device at drivers/mtd/rammtd.c. But an architecture-specific MTD driver
+    can be used instead by defining CONFIG_EXAMPLES_MTDRWB_ARCHINIT.  In
+    this case, the initialization logic will call mtdrwb_archinitialize()
+    to obtain the MTD driver instance.
+
+  When CONFIG_EXAMPLES_MTDRWB_ARCHINIT is not defined, this test will use
+  the RAM MTD device at drivers/mtd/rammtd.c to simulate FLASH. The size of
+  the allocated RAM drive will be: CONFIG_EXMPLES_RAMMTD_ERASESIZE *
+  CONFIG_EXAMPLES_MTDRWB_NEBLOCKS
+
+  * CONFIG_EXAMPLES_MTDRWB_ERASESIZE - This value gives the size of one
+    erase block in the MTD RAM device. This must exactly match the default
+    configuration in drivers/mtd/rammtd.c!
+  * CONFIG_EXAMPLES_MTDRWB_NEBLOCKS - This value gives the nubmer of erase
+    blocks in MTD RAM device.
+
 examples/netpkt
 ^^^^^^^^^^^^^^^
 
diff --git a/apps/examples/mtdrwb/.gitignore b/apps/examples/mtdrwb/.gitignore
new file mode 100644
index 000000000..fa1ec7579
--- /dev/null
+++ b/apps/examples/mtdrwb/.gitignore
@@ -0,0 +1,11 @@
+/Make.dep
+/.depend
+/.built
+/*.asm
+/*.obj
+/*.rel
+/*.lst
+/*.sym
+/*.adb
+/*.lib
+/*.src
diff --git a/apps/examples/mtdrwb/Kconfig b/apps/examples/mtdrwb/Kconfig
new file mode 100644
index 000000000..8512f458e
--- /dev/null
+++ b/apps/examples/mtdrwb/Kconfig
@@ -0,0 +1,67 @@
+#
+# For a description of the syntax of this configuration file,
+# see misc/tools/kconfig-language.txt.
+#
+
+config EXAMPLES_MTDRWB
+	bool "MTD R/W buffer test"
+	default n
+	depends on (MTD_WRBUFFER || MTD_READAHEAD) && !BUILD_PROTECTED && !BUILD_KERNEL
+	---help---
+		Enable the MTD R/W buffer test example.
+
+		NOTE: This example uses some internal NuttX interfaces and, hence,
+		is not available in the kernel build.
+
+if EXAMPLES_MTDRWB
+
+config EXAMPLES_MTDRWB_PROGNAME
+	string "Program name"
+	default "mtdrwb"
+	depends on BUILD_KERNEL
+	---help---
+		This is the name of the program that will be use when the NSH ELF
+		program is installed.
+
+config EXAMPLES_MTDRWB_ARCHINIT
+	bool "Architecture-specific initialization"
+	default n
+	---help---
+		The default is to use the RAM MTD device at drivers/mtd/rammtd.c.
+		But an architecture-specific MTD driver can be used instead by
+		defining EXAMPLES_MTDRWB_ARCHINIT.  In this case, the
+		initialization logic will call mtdrwb_archinitialize() to obtain
+		the MTD driver instance.
+
+if !EXAMPLES_MTDRWB_ARCHINIT
+
+config EXAMPLES_MTDRWB_ERASESIZE
+	int "Size of one erase blocks (simulated)"
+	default 4096
+	depends on !EXAMPLES_MTDRWB_ARCHINIT
+	---help---
+		When EXAMPLES_MTDRWB_ARCHINIT is not defined, this test will use
+		the RAM MTD device at drivers/mtd/rammtd.c to simulate FLASH.  In
+		this case, this value must be provided to give the size of one erase
+		simulated erase blocks one MTD RAM device.
+
+		The size of the allocated RAM drive will be:
+
+			EXAMPLES_MTDRWB_ERASESIZE * EXAMPLES_MTDRWB_NEBLOCKS
+
+config EXAMPLES_MTDRWB_NEBLOCKS
+	int "Number of erase blocks (simulated)"
+	default 32
+	depends on !EXAMPLES_MTDRWB_ARCHINIT
+	---help---
+		When EXAMPLES_MTDRWB_ARCHINIT is not defined, this test will use
+		the RAM MTD device at drivers/mtd/rammtd.c to simulate FLASH.  In
+		this case, this value must be provided to give the number of erase
+		blocks in MTD RAM device.
+
+		The size of the allocated RAM drive will be:
+
+			EXAMPLES_MTDRWB_ERASESIZE * EXAMPLES_MTDRWB_NEBLOCKS
+
+endif # EXAMPLES_MTDRWB_ARCHINIT
+endif # EXAMPLES_MTDRWB
diff --git a/apps/examples/mtdrwb/Makefile b/apps/examples/mtdrwb/Makefile
new file mode 100755
index 000000000..48a292296
--- /dev/null
+++ b/apps/examples/mtdrwb/Makefile
@@ -0,0 +1,124 @@
+############################################################################
+# apps/examplex/mtdrwb/Makefile
+#
+#   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# 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.
+#
+############################################################################
+
+-include $(TOPDIR)/.config
+-include $(TOPDIR)/Make.defs
+include $(APPDIR)/Make.defs
+
+# Hello, World! Example
+
+ASRCS =
+CSRCS =
+MAINSRC = mtdrwb_main.c
+
+AOBJS = $(ASRCS:.S=$(OBJEXT))
+COBJS = $(CSRCS:.c=$(OBJEXT))
+MAINOBJ = $(MAINSRC:.c=$(OBJEXT))
+
+SRCS = $(ASRCS) $(CSRCS) $(MAINSRC)
+OBJS = $(AOBJS) $(COBJS)
+
+ifneq ($(CONFIG_BUILD_KERNEL),y)
+  OBJS += $(MAINOBJ)
+endif
+
+ifeq ($(CONFIG_WINDOWS_NATIVE),y)
+  BIN = ..\..\libapps$(LIBEXT)
+else
+ifeq ($(WINTOOL),y)
+  BIN = ..\\..\\libapps$(LIBEXT)
+else
+  BIN = ../../libapps$(LIBEXT)
+endif
+endif
+
+ifeq ($(WINTOOL),y)
+  INSTALL_DIR = "${shell cygpath -w $(BIN_DIR)}"
+else
+  INSTALL_DIR = $(BIN_DIR)
+endif
+
+CONFIG_EXAMPLES_MTDRWB_PROGNAME ?= mtdrwb$(EXEEXT)
+PROGNAME = $(CONFIG_XYZ_PROGNAME)
+
+ROOTDEPPATH = --dep-path .
+
+# Common build
+
+VPATH =
+
+all: .built
+.PHONY: clean depend distclean
+
+$(AOBJS): %$(OBJEXT): %.S
+	$(call ASSEMBLE, $<, $@)
+
+$(COBJS) $(MAINOBJ): %$(OBJEXT): %.c
+	$(call COMPILE, $<, $@)
+
+.built: $(OBJS)
+	$(call ARCHIVE, $(BIN), $(OBJS))
+	@touch .built
+
+ifeq ($(CONFIG_BUILD_KERNEL),y)
+$(BIN_DIR)$(DELIM)$(PROGNAME): $(OBJS) $(MAINOBJ)
+	@echo "LD: $(PROGNAME)"
+	$(Q) $(LD) $(LDELFFLAGS) $(LDLIBPATH) -o $(INSTALL_DIR)$(DELIM)$(PROGNAME) $(ARCHCRT0OBJ) $(MAINOBJ) $(LDLIBS)
+	$(Q) $(NM) -u  $(INSTALL_DIR)$(DELIM)$(PROGNAME)
+
+install: $(BIN_DIR)$(DELIM)$(PROGNAME)
+
+else
+install:
+
+endif
+
+context:
+
+.depend: Makefile $(SRCS)
+	@$(MKDEP) $(ROOTDEPPATH) "$(CC)" -- $(CFLAGS) -- $(SRCS) >Make.dep
+	@touch $@
+
+depend: .depend
+
+clean:
+	$(call DELFILE, .built)
+	$(call CLEAN)
+
+distclean: clean
+	$(call DELFILE, Make.dep)
+	$(call DELFILE, .depend)
+
+-include Make.dep
diff --git a/apps/examples/mtdrwb/mtdrwb_main.c b/apps/examples/mtdrwb/mtdrwb_main.c
new file mode 100644
index 000000000..73b097303
--- /dev/null
+++ b/apps/examples/mtdrwb/mtdrwb_main.c
@@ -0,0 +1,443 @@
+/****************************************************************************
+ * examplex/mtdrwb/mtdrwb_main.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/mtd/mtd.h>
+#include <nuttx/fs/fs.h>
+#include <nuttx/fs/ioctl.h>
+
+#ifdef CONFIG_EXAMPLES_MTDRWB
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************/
+
+#if !defined(CONFIG_MTD_WRBUFFER) && !defined(CONFIG_MTD_READAHEAD)
+#  error CONFIG_MTD_WRBUFFER or CONFIG_MTD_READAHEAD must be selected
+#endif
+
+/* The default is to use the RAM MTD device at drivers/mtd/rammtd.c.  But
+ * an architecture-specific MTD driver can be used instead by defining
+ * CONFIG_EXAMPLES_MTDRWB_ARCHINIT.  In this case, the initialization logic
+ * will call mtdrwb_archinitialize() to obtain the MTD driver instance.
+ */
+
+#ifndef CONFIG_EXAMPLES_MTDRWB_ARCHINIT
+
+/* Make sure that the RAM MTD driver is enabled */
+
+#  ifndef CONFIG_RAMMTD
+#    error "CONFIG_RAMMTD is required without CONFIG_EXAMPLES_MTDRWB_ARCHINIT"
+#  endif
+
+/* This must exactly match the default configuration in drivers/mtd/rammtd.c */
+
+#  ifndef CONFIG_RAMMTD_ERASESIZE
+#    define CONFIG_RAMMTD_ERASESIZE 4096
+#  endif
+
+/* Given the ERASESIZE, CONFIG_EXAMPLES_MTDRWB_NEBLOCKS will determine the
+ * size of the RAM allocation needed.
+ */
+
+#  ifndef CONFIG_EXAMPLES_MTDRWB_NEBLOCKS
+#    define CONFIG_EXAMPLES_MTDRWB_NEBLOCKS (32)
+#  endif
+
+#  undef MTDRWB_BUFSIZE
+#  define MTDRWB_BUFSIZE \
+    (CONFIG_RAMMTD_ERASESIZE * CONFIG_EXAMPLES_MTDRWB_NEBLOCKS)
+
+#endif
+
+/* Debug ********************************************************************/
+#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_FS)
+#  define message    syslog
+#  define msgflush()
+#else
+#  define message    printf
+#  define msgflush() fflush(stdout);
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct mtdweb_filedesc_s
+{
+  FAR char *name;
+  bool deleted;
+  size_t len;
+  uint32_t crc;
+};
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+/* Pre-allocated simulated flash */
+
+#ifndef CONFIG_EXAMPLES_MTDRWB_ARCHINIT
+static uint8_t g_simflash[MTDRWB_BUFSIZE];
+#endif
+
+/****************************************************************************
+ * External Functions
+ ****************************************************************************/
+
+#ifdef CONFIG_EXAMPLES_MTDRWB_ARCHINIT
+extern FAR struct mtd_dev_s *mtdrwb_archinitialize(void);
+#endif
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: mtdrwb_main
+ ****************************************************************************/
+
+#ifdef CONFIG_BUILD_KERNEL
+int main(int argc, FAR char *argv[])
+#else
+int mtdrwb_main(int argc, char *argv[])
+#endif
+{
+  FAR struct mtd_dev_s *mtdraw;
+  FAR struct mtd_dev_s *mtdrwb;
+  FAR struct mtd_geometry_s geo;
+  FAR uint32_t *buffer;
+  ssize_t nbytes;
+  off_t nblocks;
+  off_t offset;
+  off_t check;
+  off_t sectoff;
+  off_t seekpos;
+  unsigned int blkpererase;
+  int fd;
+  int i;
+  int j;
+  int k;
+  int ret;
+
+  /* Create and initialize a RAM MTD FLASH driver instance */
+
+#ifdef CONFIG_EXAMPLES_MTDRWB_ARCHINIT
+  mtdraw = mtdrwb_archinitialize();
+#else
+  mtdraw = rammtd_initialize(g_simflash, MTDRWB_BUFSIZE);
+#endif
+  if (!mtdraw)
+    {
+      message("ERROR: Failed to create RAM MTD instance\n");
+      msgflush();
+      exit(1);
+    }
+
+  /* Perform the IOCTL to erase the entire FLASH part */
+
+  ret = mtdraw->ioctl(mtdraw, MTDIOC_BULKERASE, 0);
+  if (ret < 0)
+    {
+      message("ERROR: MTDIOC_BULKERASE ioctl failed: %d\n", ret);
+    }
+
+  /* Initialize to support buffering on the MTD device */
+
+  mtdrwb = mtd_rwb_initialize(mtdraw);
+  if (!mtdrwb)
+    {
+      message("ERROR: Failed to create RAM MTD R/W buffering\n");
+      msgflush();
+      exit(2);
+    }
+
+  /* Initialize to provide an FTL block driver on the MTD FLASH interface.
+   *
+   * NOTE:  We could just skip all of this FTL and BCH stuff.  We could
+   * instead just use the MTD drivers bwrite and bread to perform this
+   * test.  Creating the character drivers, however, makes this test more
+   * interesting.
+   */
+
+  ret = ftl_initialize(0, mtdrwb);
+  if (ret < 0)
+    {
+      message("ERROR: ftl_initialize /dev/mtdblock0 failed: %d\n", ret);
+      msgflush();
+      exit(3);
+    }
+
+  /* Now create a character device on the block device */
+
+  ret = bchdev_register("/dev/mtdblock0", "/dev/mtd0", false);
+  if (ret < 0)
+    {
+      message("ERROR: bchdev_register /dev/mtd0 failed: %d\n", ret);
+      msgflush();
+      exit(4);
+    }
+
+  /* Get the geometry of the FLASH device */
+
+  ret = mtdrwb->ioctl(mtdrwb, MTDIOC_GEOMETRY, (unsigned long)((uintptr_t)&geo));
+  if (ret < 0)
+    {
+      fdbg("ERROR: mtdrwb->ioctl failed: %d\n", ret);
+      exit(5);
+    }
+
+  message("Flash Geometry:\n");
+  message("  blocksize:      %lu\n", (unsigned long)geo.blocksize);
+  message("  erasesize:      %lu\n", (unsigned long)geo.erasesize);
+  message("  neraseblocks:   %lu\n", (unsigned long)geo.neraseblocks);
+
+  /* Allocate a buffer */
+
+  buffer = (FAR uint32_t *)malloc(geo.blocksize);
+  if (!buffer)
+    {
+      message("ERROR: failed to allocate a sector buffer\n");
+      msgflush();
+      exit(6);
+    }
+
+  /* Open the MTD FLASH character driver for writing */
+
+  fd = open("/dev/mtd0", O_WRONLY);
+  if (fd < 0)
+    {
+      message("ERROR: open /dev/mtd0 failed: %d\n", errno);
+      msgflush();
+      exit(7);
+    }
+
+  /* Now write the offset into every block */
+
+  message("Initializing media:\n");
+
+  offset = 0;
+  for (i = 0; i < geo.neraseblocks; i++)
+    {
+      for (j = 0; j < blkpererase; j++)
+        {
+          /* Fill the block with the offset */
+
+          for (k = 0; k < geo.blocksize / sizeof(uint32_t); k++)
+            {
+              buffer[k] = offset;
+              offset += 4;
+            }
+
+          /* And write it using the character driver */
+
+          nbytes = write(fd, buffer, geo.blocksize);
+          if (nbytes < 0)
+            {
+              message("ERROR: write to /dev/mtd0 failed: %d\n", errno);
+              msgflush();
+              exit(8);
+            }
+        }
+    }
+
+  close(fd);
+
+  /* Open the MTD character driver for writing */
+
+  fd = open("/dev/mtd0", O_RDWR);
+  if (fd < 0)
+    {
+      message("ERROR: open /dev/mtd0 failed: %d\n", errno);
+      msgflush();
+      exit(9);
+    }
+
+  /* Now verify the offset in every block */
+
+  check = offset;
+  sectoff = 0;
+
+  for (j = 0; j < nblocks; j++)
+    {
+#if 0 /* Too much */
+      message("  block=%u offset=%lu\n", j, (unsigned long) check);
+#endif
+      /* Seek to the next read position */
+
+      seekpos = lseek(fd, sectoff, SEEK_SET);
+      if (seekpos != sectoff)
+        {
+          message("ERROR: lseek to offset %ld failed: %d\n",
+                   (unsigned long)sectoff, errno);
+          msgflush();
+          exit(10);
+        }
+
+      /* Read the next block into memory */
+
+      nbytes = read(fd, buffer, geo.blocksize);
+      if (nbytes < 0)
+        {
+          message("ERROR: read from /dev/mtd0 failed: %d\n", errno);
+          msgflush();
+          exit(11);
+        }
+      else if (nbytes == 0)
+        {
+          message("ERROR: Unexpected end-of file in /dev/mtd0\n");
+          msgflush();
+          exit(12);
+        }
+      else if (nbytes != geo.blocksize)
+        {
+          message("ERROR: Unexpected read size from /dev/mtd0 : %ld\n",
+                  (unsigned long)nbytes);
+          msgflush();
+          exit(13);
+        }
+
+      /* Since we forced the size of the partition to be an even number
+       * of erase blocks, we do not expect to encounter the end of file
+       * indication.
+       */
+
+     else if (nbytes == 0)
+        {
+          message("ERROR: Unexpected end of file on /dev/mtd0\n");
+          msgflush();
+          exit(14);
+        }
+
+     /* This is not expected at all */
+
+     else if (nbytes != geo.blocksize)
+       {
+          message("ERROR: Short read from /dev/mtd0 failed: %lu\n",
+                  (unsigned long)nbytes);
+          msgflush();
+          exit(15);
+        }
+
+      /* Verify the offsets in the block */
+
+      for (k = 0; k < geo.blocksize / sizeof(uint32_t); k++)
+        {
+          if (buffer[k] != check)
+            {
+              message("ERROR: Bad offset %lu, expected %lu\n",
+                      (long)buffer[k], (long)check);
+              msgflush();
+              exit(16);
+            }
+
+          /* Invert the value to indicate that we have verified
+           * this value.
+           */
+
+          buffer[k] = ~check;
+          check += sizeof(uint32_t);
+        }
+
+      /* Seek to the next write position */
+
+      seekpos = lseek(fd, sectoff, SEEK_SET);
+      if (seekpos != sectoff)
+        {
+          message("ERROR: lseek to offset %ld failed: %d\n",
+                  (unsigned long)sectoff, errno);
+          msgflush();
+          exit(17);
+        }
+
+      /* Now write the block back to FLASH with the modified value */
+
+      nbytes = write(fd, buffer, geo.blocksize);
+      if (nbytes < 0)
+        {
+          message("ERROR: write to /dev/mtd0 failed: %d\n", errno);
+          msgflush();
+          exit(18);
+        }
+      else if (nbytes != geo.blocksize)
+        {
+          message("ERROR: Unexpected write size to /dev/mtd0 : %ld\n",
+                  (unsigned long)nbytes);
+          msgflush();
+          exit(19);
+        }
+
+      /* Get the offset to the next block */
+
+      sectoff += geo.blocksize;
+    }
+
+  /* Try reading one more time.  We should get the end of file */
+
+  nbytes = read(fd, buffer, geo.blocksize);
+  if (nbytes != 0)
+    {
+      message("ERROR: Expected end-of-file from /dev/mtd0 failed: %d %d\n",
+              nbytes, errno);
+      msgflush();
+      exit(20);
+    }
+
+  close(fd);
+
+  /* And exit without bothering to clean up */
+
+  message("PASS: Everything looks good\n");
+  msgflush();
+  return 0;
+}
+
+#endif /* CONFIG_EXAMPLES_MTDRWB */