Add poll() method

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1262 42af7a65-404d-4744-a932-0658087f49c3

drivers/dev_null.c

@@ -45,6 +45,7 @@
 
 #include <sys/types.h>
 #include <string.h>
+#include <poll.h>
 #include <errno.h>
 #include <nuttx/fs.h>
 
@@ -54,6 +55,9 @@
 
 static ssize_t devnull_read(FAR struct file *, FAR char *, size_t);
 static ssize_t devnull_write(FAR struct file *, FAR const char *, size_t);
+#ifndef CONFIG_DISABLE_POLL
+static int     devnull_poll(FAR struct file *filp, FAR struct pollfd *poll);
+#endif
 
 /****************************************************************************
  * Private Data
@@ -66,8 +70,10 @@ static struct file_operations devnull_fops =
   devnull_read,  /* read */
   devnull_write, /* write */
   0,             /* seek */
-  0,             /* ioctl */
-  0              /* poll */
+  0              /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , devnull_poll /* poll */
+#endif
 };
 
 /****************************************************************************
@@ -92,6 +98,25 @@ static ssize_t devnull_write(FAR struct file *filp, FAR const char *buffer, size
   return len; /* Say that everything was written */
 }
 
+/****************************************************************************
+ * Name: devnull_poll
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static int devnull_poll(FAR struct file *filp, FAR struct pollfd *fds)
+{
+  if (fds)
+    {
+      fds->revents |= (fds->events & (POLLIN|POLLOUT));
+      if (fds->revents != 0)
+        {
+          sem_post(fds->sem);
+        }
+    }
+  return OK;
+}
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/

drivers/dev_zero.c

@@ -45,6 +45,7 @@
 
 #include <sys/types.h>
 #include <string.h>
+#include <poll.h>
 #include <errno.h>
 #include <nuttx/fs.h>
 
@@ -54,6 +55,9 @@
 
 static ssize_t devzero_read(FAR struct file *, FAR char *, size_t);
 static ssize_t devzero_write(FAR struct file *, FAR const char *, size_t);
+#ifndef CONFIG_DISABLE_POLL
+static int     devzero_poll(FAR struct file *filp, FAR struct pollfd *fds);
+#endif
 
 /****************************************************************************
  * Private Data
@@ -66,25 +70,54 @@ static struct file_operations devzero_fops =
   devzero_read,  /* read */
   devzero_write, /* write */
   0,             /* seek */
-  0,             /* ioctl */
-  0              /* poll */
+  0              /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , devzero_poll /* poll */
+#endif
 };
 
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: devzero_read
+ ****************************************************************************/
+
 static ssize_t devzero_read(FAR struct file *filp, FAR char *buffer, size_t len)
 {
   memset(buffer, 0, len);
   return len;
 }
 
+/****************************************************************************
+ * Name: devzero_write
+ ****************************************************************************/
+
 static ssize_t devzero_write(FAR struct file *filp, FAR const char *buffer, size_t len)
 {
   return len;
 }
 
+/****************************************************************************
+ * Name: devzero_poll
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static int devzero_poll(FAR struct file *filp, FAR struct pollfd *fds)
+{
+  if (fds)
+    {
+      fds->revents |= (fds->events & (POLLIN|POLLOUT));
+      if (fds->revents != 0)
+        {
+          sem_post(fds->sem);
+        }
+    }
+  return OK;
+}
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/

drivers/fifo.c

@@ -74,8 +74,10 @@ static struct file_operations fifo_fops =
   pipecommon_read,  /* read */
   pipecommon_write, /* write */
   0,                /* seek */
-  0,                /* ioctl */
-  0                 /* poll */
+  0                 /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , pipecommon_poll /* poll */
+#endif
 };
 
 /****************************************************************************

drivers/pipe.c

@@ -82,8 +82,10 @@ static struct file_operations pipe_fops =
   pipecommon_read,   /* read */
   pipecommon_write,  /* write */
   0,                 /* seek */
-  0,                 /* ioctl */
-  0,                 /* pipe */
+  0                  /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , pipecommon_poll  /* poll */
+#endif
 };
 
 static sem_t  g_pipesem     = { 1 };

drivers/pipe_common.c

@@ -52,6 +52,8 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <assert.h>
+#include <debug.h>
+
 #include <nuttx/fs.h>
 
 #include "pipe_common.h"
@@ -96,6 +98,33 @@ static void pipecommon_semtake(sem_t *sem)
     }
 }
 
+/****************************************************************************
+ * Name: pipecommon_pollnotify
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static void pipecommon_pollnotify(FAR struct pipe_dev_s *dev, pollevent_t eventset)
+{
+  int i;
+
+  for (i = 0; i < CONFIG_DEV_PIPE_NPOLLWAITERS; i++)
+    {
+      struct pollfd *fds = dev->d_fds[i];
+      if (fds)
+        {
+          fds->revents |= (fds->events & eventset);
+          if (fds->revents != 0)
+            {
+              fvdbg("Report events: %02x\n", fds->revents);
+              sem_post(fds->sem);
+            }
+        }
+    }
+}
+#else
+#  define pipecommon_pollnotify(dev,event)
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -168,6 +197,10 @@ int pipecommon_open(FAR struct file *filep)
             }
         }
 
+      /* There is no, file-specific private data (at least not yet) */
+
+      filep->f_priv = NULL;
+
       /* Increment the reference count on the pipe instance */
 
       dev->d_refs++;
@@ -335,6 +368,7 @@ ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len)
       sem_post(&dev->d_bfsem);
       ret = sem_wait(&dev->d_rdsem);
       sched_unlock();
+
       if (ret < 0  || sem_wait(&dev->d_bfsem) < 0) 
         {
           return ERROR;
@@ -361,8 +395,12 @@ ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len)
       sem_post(&dev->d_wrsem);
     }
 
+  /* Notify all poll/select waiters that they can write to the FIFO */
+
+  pipecommon_pollnotify(dev, POLLOUT);
+
   sem_post(&dev->d_bfsem);
-  return nread;	    
+  return nread;
 }
 
 /****************************************************************************
@@ -426,6 +464,10 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer, size_t
                   sem_post(&dev->d_rdsem);
                 }
 
+              /* Notify all poll/select waiters that they can write to the FIFO */
+
+              pipecommon_pollnotify(dev, POLLIN);
+
               /* Return the number of bytes written */
 
               sem_post(&dev->d_bfsem);
@@ -470,4 +512,97 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer, size_t
     }
 }
 
+/****************************************************************************
+ * Name: pipecommon_poll
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+int pipecommon_poll(FAR struct file *filep, FAR struct pollfd *fds)
+{
+  struct inode      *inode    = filep->f_inode;
+  struct pipe_dev_s *dev      = inode->i_private;
+  pollevent_t        eventset;
+  pipe_ndx_t         nbytes;
+  int                i;
+
+  /* Some sanity checking */
+#if CONFIG_DEBUG
+  if (!dev)
+    {
+      return -ENODEV;
+    }
+#endif
+
+  /* Find an available slot for the poll structure reference */
+
+  pipecommon_semtake(&dev->d_bfsem);
+  for (i = 0; i < CONFIG_DEV_PIPE_NPOLLWAITERS; i++)
+    {
+      /* Find the slot with the value equal to filep->f_priv.  If there
+       * is not previously installed poll structure, then f_priv will
+       * be NULL and we will find the first unused slot.  If f_priv is
+       * is non-NULL, then we will find the slot that was used for the
+       * previous setup.
+       */
+
+      if (dev->d_fds[i] == filep->f_priv)
+        {
+          dev->d_fds[i] = fds;
+          break;
+        }
+    }
+
+  if (i >= CONFIG_DEV_PIPE_NPOLLWAITERS)
+    {
+      DEBUGASSERT(fds == NULL);
+      return -EBUSY;
+    }
+
+  /* Set or clear the poll event structure reference in the 'struct file'
+   * private data.
+   */
+
+  filep->f_priv = fds;
+
+  /* Check if we should immediately notify on any of the requested events */
+
+  if (fds)
+    {
+      /* Determine how many bytes are in the buffer */
+
+      if (dev->d_wrndx >= dev->d_rdndx)
+        {
+          nbytes = dev->d_wrndx - dev->d_rdndx;
+        }
+      else
+        {
+          nbytes = (CONFIG_DEV_PIPE_SIZE-1) + dev->d_wrndx - dev->d_rdndx;
+        }
+
+      /* Notify the POLLOUT event if the pipe is not full */
+
+      eventset = 0;
+      if (nbytes < (CONFIG_DEV_PIPE_SIZE-1))
+        {
+          eventset |= POLLOUT;
+        }
+
+      /* Notify the POLLIN event if the pipe is not empty */
+
+      if (nbytes > 0)
+        {
+          eventset |= POLLIN;
+        }
+
+      if (eventset)
+        {
+          pipecommon_pollnotify(dev, eventset);
+        }
+    }
+
+  sem_post(&dev->d_bfsem);
+  return OK;
+}
+#endif
+
 #endif /* CONFIG_DEV_PIPE_SIZE > 0 */

drivers/pipe_common.h

@@ -42,16 +42,24 @@
 
 #include <nuttx/config.h>
 #include <sys/types.h>
+#include <poll.h>
 
 #ifndef CONFIG_DEV_PIPE_SIZE
 #  define CONFIG_DEV_PIPE_SIZE 1024
 #endif
+
 #if CONFIG_DEV_PIPE_SIZE > 0
 
 /****************************************************************************
  * Definitions
  ****************************************************************************/
 
+/* Maximum number of threads than can be waiting for POLL events */
+
+#ifndef CONFIG_DEV_PIPE_NPOLLWAITERS
+#  define CONFIG_DEV_PIPE_NPOLLWAITERS 2
+#endif
+
 /* Maximum number of open's supported on pipe */
 
 #define CONFIG_DEV_PIPE_MAXUSER 255
@@ -70,6 +78,11 @@ typedef uint16 pipe_ndx_t;  /* 16-bit index */
 typedef ubyte pipe_ndx_t;   /*  8-bit index */
 #endif
 
+/* This structure represents the state of one pipe.  A reference to this
+ * structure is retained in the i_private field of the inode whenthe pipe/fifo
+ * device is registered.
+ */
+
 struct pipe_dev_s
 {
   sem_t      d_bfsem;       /* Used to serialize access to d_buffer and indices */
@@ -80,9 +93,21 @@ struct pipe_dev_s
   ubyte      d_refs;        /* References counts on pipe (limited to 255) */
   ubyte      d_nwriters;    /* Number of reference counts for write access */
   ubyte      d_pipeno;      /* Pipe minor number */
-  ubyte     *d_buffer;      /* Buffer alloated when device opend */
+  ubyte     *d_buffer;      /* Buffer allocated when device opened */
+
+  /* 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 *d_fds[CONFIG_DEV_PIPE_NPOLLWAITERS];
+#endif
 };
 
+/* 
+ */
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/
@@ -100,6 +125,9 @@ EXTERN int     pipecommon_open(FAR struct file *filep);
 EXTERN int     pipecommon_close(FAR struct file *filep);
 EXTERN ssize_t pipecommon_read(FAR struct file *, FAR char *, size_t);
 EXTERN ssize_t pipecommon_write(FAR struct file *, FAR const char *, size_t);
+#ifndef CONFIG_DISABLE_POLL
+EXTERN int     pipecommon_poll(FAR struct file *filep, FAR struct pollfd *fds);
+#endif
 
 #undef EXTERN
 #ifdef __cplusplus