Add a RAM-based logging device

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4379 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 590 insertions, 0 deletions

diff --git a/nuttx/drivers/ramlog.c b/nuttx/drivers/ramlog.c
new file mode 100644
index 000000000..79f57636c
--- /dev/null
+++ b/nuttx/drivers/ramlog.c
@@ -0,0 +1,590 @@
+/****************************************************************************
+ * drivers/ramlog.c
+ *
+ *   Copyright (C) 2012 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 <sys/types.h>
+#include <sys/ioctl.h>
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <string.h>
+#include <poll.h>
+#include <errno.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/fs.h>
+#include <nuttx/kmalloc.h>
+#include <nuttx/fs.h>
+#include <nuttx/arch.h>
+//#include <nuttx/ramlog.h>
+
+#include <arch/irq.h>
+
+#ifdef CONFIG_RAMLOG
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+/* Configuration ************************************************************/
+/* CONFIG_RAMLOG - Enables the RAM logging feature
+ * CONFIG_RAMLOG_CONSOLE - Use the RAM logging device as a system console.
+ * CONFIG_RAMLOG_SYSLOG - Use the RAM logging device for the syslogging
+ *   interface.  This should have:
+ *   CONFIG_SYSLOG=ramlog
+ * CONFIG_RAMLOG_NPOLLWAITERS - The number of threads than can be waiting
+ *   for this driver on poll().  Default: 4
+ */
+
+#ifndef CONFIG_RAMLOG_NPOLLWAITERS
+#  define CONFIG_RAMLOG_NPOLLWAITERS 4
+#endif
+
+#ifndef CONFIG_SYSLOG
+#  undef CONFIG_RAMLOG_SYSLOG
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct ramlog_dev_s
+{
+  volatile uint8_t  rl_nwaiters;     /* Number of threads waiting for data */
+  volatile uint16_t rl_head;         /* The head index (where data is added) */
+  volatile uint16_t rl_tail;         /* The tail index (where data is remove) */
+  sem_t             rl_exclsem;      /* Enforces mutually exclusive access */
+  sem_t             rl_waitsem;      /* Used to wait for data */
+  size_t            rl_bufsize;      /* Size of the RAM buffer */
+  FAR char         *rl_buffer;       /* Circular RAM buffer */
+
+  /* The following is a list if poll structures of threads waiting for
+   * driver events. The 'struct pollfd' reference for each open is also
+   * retained in the f_priv field of the 'struct file'.
+   */
+
+#ifndef CONFIG_DISABLE_POLL
+  struct pollfd *rl_fds[CONFIG_RAMLOG_NPOLLWAITERS];
+#endif
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static ssize_t ramlog_read(FAR struct file *, FAR char *, size_t);
+static ssize_t ramlog_write(FAR struct file *, FAR const char *, size_t);
+#ifndef CONFIG_DISABLE_POLL
+static int     ramlog_poll(FAR struct file *filep, FAR struct pollfd *fds,
+                           bool setup);
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct file_operations g_ramlogfops =
+{
+  0,             /* open */
+  0,             /* close */
+  ramlog_read,   /* read */
+  ramlog_write,  /* write */
+  0,             /* seek */
+  0              /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , ramlog_poll  /* poll */
+#endif
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: ramlog_pollnotify
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static void ramlog_pollnotify(FAR struct ramlog_dev_s *priv, pollevent_t eventset)
+{
+  FAR struct pollfd *fds;
+  irqstate_t flags;
+  int i;
+
+  /* This function may be called from an interrupt handler */
+
+  for (i = 0; i < CONFIG_RAMLOG_NPOLLWAITERS; i++)
+    {
+      flags = irqsave();
+      fds = priv->rl_fds[i];
+      if (fds)
+        {
+          fds->revents |= (fds->events & eventset);
+          if (fds->revents != 0)
+            {
+              sem_post(fds->sem);
+            }
+        }
+      irqrestore(flags);
+    }
+}
+#else
+#  define ramlog_pollnotify(priv,event)
+#endif
+
+/****************************************************************************
+ * Name: ramlog_read
+ ****************************************************************************/
+
+static ssize_t ramlog_read(FAR struct file *filep, FAR char *buffer, size_t len)
+{
+  struct inode *inode  = filep->f_inode;
+  struct ramlog_dev_s *priv;
+  ssize_t nread;
+  char ch;
+  int ret;
+
+  /* Some sanity checking */
+
+  DEBUGASSERT(inode && inode->i_private);
+  priv = inode->i_private;
+
+  /* If the circular buffer is empty, then wait for something to be written
+   * to it.  This function may NOT be called from an interrupt handler.
+   */
+
+  DEBUGASSERT(!up_interrupt_context());
+
+  /* Get exclusive access to the rl_tail index */
+
+  ret = sem_wait(&priv->rl_exclsem);
+  if (ret < 0)
+    {
+      return ret;
+    }
+
+  /* Loop until something is read */
+
+  for (nread = 0; nread < len; )
+    {
+      /* Get the next byte from the buffer */
+
+      if (priv->rl_head == priv->rl_tail)
+        {
+          /* The circular buffer is empty.  Did we read anything? */
+
+          if (nread > 0)
+            {
+              /* Yes.. re-enable interrupts and the break out to return what
+               * we have.
+               */
+
+              break;
+            }
+
+          /* If the driver was opened with O_NONBLOCK option, then don't wait.
+           * Re-enable interrupts and return EGAIN.
+           */
+
+          if (filep->f_oflags & O_NONBLOCK)
+            {
+              nread = -EAGAIN;
+              break;
+            }
+
+          /* Otherwise, wait for something to be written to the circular
+           * buffer. Increment the number of waiters so that the ramlog_write()
+           * will not that it needs to post the semaphore to wake us up.
+           */
+
+          sched_lock();
+          priv->rl_nwaiters++;
+          sem_post(&priv->rl_exclsem);
+
+          /* We may now be pre-empted!  But that should be okay because we
+           * have already incremented nwaiters.  Pre-emptions is disabled
+           * but will be re-enabled while we are waiting.
+           */
+
+          ret = sem_wait(&priv->rl_waitsem);
+
+          /* Interrupts will be disabled when we return.  So the decrementing
+           * rl_nwaiters here is safe.
+           */
+
+          priv->rl_nwaiters--;
+          sched_unlock();
+
+          /* Did we successfully get the rl_waitsem? */
+
+          if (ret >= 0)
+            {
+              /* Yes... then retake the mutual exclusion semaphore */
+
+              ret = sem_wait(&priv->rl_exclsem);
+            }
+
+          /* Was the semaphore wait successful? Did we successful re-take the
+           * mutual exclusion semaphore?
+           */
+
+          if (ret < 0) 
+            {
+              /* No.. One of the two sem_wait's failed. */
+
+              int errval = errno;
+
+              /* Were we awakened by a signal?  Did we read anything before
+               * we received the signal?
+               */
+
+              if (errval != EINTR || nread >= 0)
+                {
+                  /* Yes.. return the error. */
+
+                  nread = -errval;
+                }
+
+              /* Break out to return what we have.  Note, we can't exactly
+               * "break" out because whichever error occurred, we do not hold
+               * the exclusion semaphore.
+               */
+
+              goto errout_without_sem;
+            }
+        }
+      else
+        {
+          /* The circular buffer is not empty, get the next byte from the
+           * tail index.
+           */
+
+          ch = priv->rl_buffer[priv->rl_tail];
+
+          /* Increment the tail index and re-enable interrupts */
+
+          if (++priv->rl_tail >= priv->rl_bufsize)
+            {
+              priv->rl_tail = 0;
+            }
+
+          /* Add the character to the user buffer */
+
+          buffer[nread] = ch;
+          nread++;
+        }
+    }
+
+  /* Relinquish the mutual exclusion semaphore */
+
+  sem_post(&priv->rl_exclsem);
+
+  /* Notify all poll/select waiters that they can write to the FIFO */
+
+errout_without_sem:
+  if (nread > 0)
+    {
+      ramlog_pollnotify(priv, POLLOUT);
+    }
+  return nread;
+}
+
+/****************************************************************************
+ * Name: ramlog_write
+ ****************************************************************************/
+
+static ssize_t ramlog_write(FAR struct file *filep, FAR const char *buffer, size_t len)
+{
+  struct inode *inode = filep->f_inode;
+  struct ramlog_dev_s *priv;
+  irqstate_t flags;
+  ssize_t nwritten;
+  int nexthead;
+  int i;
+
+  /* Some sanity checking */
+
+  DEBUGASSERT(inode && inode->i_private);
+  priv = inode->i_private;
+
+ /* Loop until all of the bytes have been written.  This function may be
+  * called from an interrupt handler!  Semaphores cannot be used!
+  *
+  * The write logic only needs to modify the rl_head index.  Therefore,
+  * there is a difference in the way that rl_head and rl_tail are protected:
+  * rl_tail is protected with a semaphore; rl_tail is protected by disabling
+  * interrupts.
+  */
+
+  for (nwritten = 0; nwritten < len; nwritten++)
+    {
+      /* Disable interrupts (in case we are NOT called from interrupt handler) */
+
+      flags = irqsave();
+
+      /* Calculate the write index AFTER the next byte is written */
+
+      nexthead = priv->rl_head + 1;
+      if (nexthead >= priv->rl_bufsize)
+        {
+          nexthead = 0;
+        }
+
+      /* Would the next write overflow the circular buffer? */
+
+      if (nexthead == priv->rl_tail)
+        {
+          /* Yes... then break out of the loop to return the number of bytes
+           * written.  The data to be written is dropped on the floor.
+           */
+
+          return nwritten;
+        }
+
+      /* No... copy the byte and re-enable interrupts */
+
+      priv->rl_buffer[priv->rl_head] = buffer[nwritten];
+      priv->rl_head = nexthead;
+      irqrestore(flags);
+    }
+
+  /* Was anything written? */
+
+  if (nwritten > 0)
+    {
+      /* Are there threads waiting for read data? */
+
+      flags = irqsave();
+      for (i = 0; i < priv->rl_nwaiters; i++)
+        {
+          /* Yes.. Notify all of the waiting readers that more data is available */
+
+          sem_post(&priv->rl_waitsem);
+        }
+
+      /* Notify all poll/select waiters that they can write to the FIFO */
+
+      ramlog_pollnotify(priv, POLLIN);
+    }
+ 
+  /* Return the number of bytes written */
+
+  return nwritten;
+}
+
+/****************************************************************************
+ * Name: ramlog_poll
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+int ramlog_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup)
+{
+  FAR struct inode *inode = filep->f_inode;
+  FAR struct ramlog_dev_s *priv;
+  pollevent_t eventset;
+  int ndx;
+  int ret;
+  int i;
+
+  /* Some sanity checking */
+
+  DEBUGASSERT(inode && inode->i_private);
+  priv = inode->i_private;
+
+  /* Get exclusive access to the poll structures */
+
+  ret = sem_wait(&priv->rl_exclsem);
+  if (ret < 0)
+    {
+      int errval = errno;
+      return -errval;
+    }
+
+  /* Are we setting up the poll?  Or tearing it down? */
+
+  if (setup)
+    {
+      /* This is a request to set up the poll.  Find an available
+       * slot for the poll structure reference
+       */
+
+      for (i = 0; i < CONFIG_RAMLOG_NPOLLWAITERS; i++)
+        {
+          /* Find an available slot */
+
+          if (!priv->rl_fds[i])
+            {
+              /* Bind the poll structure and this slot */
+
+              priv->rl_fds[i] = fds;
+              fds->priv       = &priv->rl_fds[i];
+              break;
+            }
+        }
+
+      if (i >= CONFIG_RAMLOG_NPOLLWAITERS)
+        {
+          fds->priv    = NULL;
+          ret          = -EBUSY;
+          goto errout;
+        }
+
+      /* Should immediately notify on any of the requested events?
+       * First, check if the xmit buffer is full.
+       */
+
+      eventset = 0;
+
+      ndx = priv->rl_head + 1;
+      if (ndx >= priv->rl_bufsize)
+        {
+          ndx = 0;
+        }
+  
+      if (ndx != priv->rl_tail)
+       {
+         eventset |= POLLOUT;
+       }
+
+      /* Check if the receive buffer is empty */
+
+      if (priv->rl_head != priv->rl_tail)
+       {
+         eventset |= POLLIN;
+       }
+
+      if (eventset)
+        {
+          ramlog_pollnotify(priv, eventset);
+        }
+
+    }
+  else if (fds->priv)
+    {
+      /* This is a request to tear down the poll. */
+
+      struct pollfd **slot = (struct pollfd **)fds->priv;
+
+#ifdef CONFIG_DEBUG
+      if (!slot)
+        {
+          ret = -EIO;
+          goto errout;
+        }
+#endif
+
+      /* Remove all memory of the poll setup */
+
+      *slot      = NULL;
+      fds->priv  = NULL;
+    }
+
+errout:
+  sem_post(&priv->rl_exclsem);
+  return ret;
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: ramlog_register
+ *
+ * Description:
+ *   Create the RAM logging device and register it at the specified path.
+ *   Mostly likely this path will be /dev/console
+ *
+ ****************************************************************************/
+
+int ramlog_register(FAR const char *devpath, FAR char *buffer, size_t buflen)
+{
+  FAR struct ramlog_dev_s *priv;
+  int ret = -ENOMEM;
+
+  /* Sanity checking */
+
+  DEBUGASSERT(devpath && buffer && buflen > 1);
+
+  /* Allocate a RAM logging device structure */
+
+  priv = (struct ramlog_dev_s *)kzalloc(sizeof(struct ramlog_dev_s));
+  if (priv)
+    {
+      /* Initialize the non-zero values in the RAM logging device structure */
+
+      sem_init(&priv->rl_exclsem, 0, 1);
+      sem_init(&priv->rl_waitsem, 0, 0);
+      priv->rl_bufsize = buflen;
+      priv->rl_buffer  = buffer;
+
+      /* Register the character driver */
+
+      ret = register_driver(devpath, &g_ramlogfops, 0666, priv);
+      if (ret < 0)
+        {
+          kfree(priv);
+        }
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: ramlog
+ *
+ * Description:
+ *   This is the low-level system logging interface.  The debugging/syslogging
+ *   interfaces are lib_rawprintf() and lib_lowprinf().  The difference is
+ *   the lib_rawprintf() writes to fd=1 (stdout) and lib_lowprintf() uses
+ *   a lower level interface that works from interrupt handlers.  This
+ *   function is a a low-level interface used to implement lib_lowprintf()
+ *   when CONFIG_RAMLOG_SYSLOG=y and CONFIG_SYSLOG=ramlog
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_RAMLOG_SYSLOG
+#  warning "Missing logic"
+#endif
+
+#endif /* CONFIG_RAMLOG */