fs/vfs: Add file descriptor based events support

fs/Kconfig

@@ -53,6 +53,34 @@ config PSEUDOFS_SOFTLINKS
 		to link a directory in the pseudo-file system, such as /bin, to
 		to a directory in a mounted volume, say /mnt/sdcard/bin.
 
+config EVENT_FD
+	bool "EventFD"
+	default n
+	---help---
+		Create a file descriptor for event notification
+
+if EVENT_FD
+
+config EVENT_FD_VFS_PATH
+    string "Path to eventfd storage"
+    default "/var/event"
+    ---help---
+        The path to where eventfd will exist in the VFS namespace.
+
+config EVENT_FD_POLL
+	bool "EventFD poll support"
+	default y
+	---help---
+		Poll support for file descriptor based events
+
+config EVENT_FD_NPOLLWAITERS
+	int "Number of eventFD poll waiters"
+	default 2
+	---help---
+		Maximum number of threads that can be waiting on poll()
+
+endif # EVENT_FD
+
 source fs/aio/Kconfig
 source fs/semaphore/Kconfig
 source fs/mqueue/Kconfig

fs/vfs/Make.defs

@@ -66,6 +66,12 @@ ifeq ($(CONFIG_NET_SENDFILE),y)
 CSRCS += fs_sendfile.c
 endif
 
+# Support for eventfd
+
+ifeq ($(CONFIG_EVENT_FD),y)
+CSRCS += fs_eventfd.c
+endif
+
 # Include vfs build support
 
 DEPPATH += --dep-path vfs

include/nuttx/fs/ioctl.h

@@ -121,6 +121,10 @@
 
 /* Terminal I/O IOCTL definitions are retained in tioctl.h */
 
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
 #include <nuttx/serial/tioctl.h>
 
 /* Watchdog driver ioctl commands *******************************************/
@@ -176,6 +180,10 @@
                                            *      int value.
                                            * OUT: Origin option.
                                            */
+#define FIOC_MINOR      _FIOC(0x000c)     /* IN:  None
+                                           * OUT: Integer that contains device
+                                           *      minor number
+                                           */
 
 /* NuttX file system ioctl definitions **************************************/
 
@@ -309,6 +317,7 @@
 #define _PWMIOC(nr)       _IOC(_PWMIOCBASE,nr)
 
 /* NuttX USB CDC/ACM serial driver ioctl definitions ************************/
+
 /* (see nuttx/usb/cdcacm.h) */
 
 #define _CAIOCVALID(c)    (_IOC_TYPE(c)==_CAIOCBASE)
@@ -322,6 +331,7 @@
 #define _BATIOC(nr)       _IOC(_BATIOCBASE,nr)
 
 /* NuttX Quadrature Encoder driver ioctl definitions ************************/
+
 /* (see nuttx/power/battery.h) */
 
 #define _QEIOCVALID(c)    (_IOC_TYPE(c)==_QEIOCBASE)
@@ -349,6 +359,7 @@
 #define _SLCDIOC(nr)      _IOC(_SLCDIOCBASE,nr)
 
 /* Wireless driver character driver ioctl definitions ***********************/
+
 /* (see nuttx/include/wireless/ioctl.h */
 
 #define _WLCIOCVALID(c)   (_IOC_TYPE(c)==_WLCIOCBASE)
@@ -368,7 +379,7 @@
 #define _TCIOCVALID(c)    (_IOC_TYPE(c)==_TCIOCBASE)
 #define _TCIOC(nr)        _IOC(_TCIOCBASE,nr)
 
-/* Joystick driver ioctl definitions ***************************************/
+/* Joystick driver ioctl definitions ****************************************/
 
 /* Discrete Joystick (see nuttx/include/input/djoystick.h */
 

include/sys/eventfd.h

@@ -0,0 +1,75 @@
+/****************************************************************************
+ * include/sys/eventfd.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_SYS_EVENTFD_H
+#define __INCLUDE_SYS_EVENTFD_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdint.h>
+#include <fcntl.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define EFD_NONBLOCK  O_NONBLOCK
+#define EFD_SEMAPHORE O_BINARY
+#define EFD_CLOEXEC   O_CLOEXEC
+
+/* Get device minor number */
+
+#define EFD_FIOC_MINOR FIOC_MINOR
+
+/****************************************************************************
+ * Public Type Declarations
+ ****************************************************************************/
+
+/* Type for event counter */
+
+typedef uint32_t eventfd_t;
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+int eventfd(unsigned int count, int flags);
+
+int eventfd_read(int fd, FAR eventfd_t *value);
+int eventfd_write(int fd, eventfd_t value);
+
+int eventfd_get_minor(int fd);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __INCLUDE_SYS_EVENTFD_H */

include/sys/syscall_lookup.h

@@ -208,6 +208,9 @@ SYSCALL_LOOKUP(pwrite,                     4)
   SYSCALL_LOOKUP(select,                   5)
   SYSCALL_LOOKUP(ppoll,                    4)
   SYSCALL_LOOKUP(pselect,                  6)
+#ifdef CONFIG_EVENT_FD
+  SYSCALL_LOOKUP(eventfd,                  2)
+#endif
 #ifdef CONFIG_NETDEV_IFINDEX
   SYSCALL_LOOKUP(if_indextoname,           2)
   SYSCALL_LOOKUP(if_nametoindex,           1)

libs/libc/Makefile

@@ -28,6 +28,7 @@ include dirent/Make.defs
 include dlfcn/Make.defs
 include endian/Make.defs
 include errno/Make.defs
+include eventfd/Make.defs
 include fixedmath/Make.defs
 include grp/Make.defs
 include hex2bin/Make.defs

libs/libc/eventfd/Make.defs

@@ -0,0 +1,27 @@
+############################################################################
+# libs/libc/eventfd/Make.defs
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+ifeq ($(CONFIG_EVENT_FD),y)
+CSRCS += lib_eventfd.c
+
+DEPPATH += --dep-path eventfd
+VPATH += :eventfd
+endif
+

libs/libc/eventfd/lib_eventfd.c

@@ -0,0 +1,57 @@
+/****************************************************************************
+ * libs/libc/lib_eventfd.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <sys/eventfd.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int eventfd_read(int fd, FAR eventfd_t *value)
+{
+  return read(fd, value, sizeof (eventfd_t)) != sizeof (eventfd_t) ? -1 : 0;
+}
+
+int eventfd_write(int fd, eventfd_t value)
+{
+  return write(fd, &value,
+      sizeof (eventfd_t)) != sizeof (eventfd_t) ? -1 : 0;
+}
+
+int eventfd_get_minor(int fd)
+{
+  int ret;
+  int minor;
+
+  ret = ioctl(fd, EFD_FIOC_MINOR, &minor);
+
+  if (ret < 0)
+    {
+      return ret;
+    }
+
+  return minor;
+}

syscall/syscall.csv

@@ -19,6 +19,7 @@
 "connect","sys/socket.h","defined(CONFIG_NET)","int","int","FAR const struct sockaddr *","socklen_t"
 "dup","unistd.h","","int","int"
 "dup2","unistd.h","","int","int","int"
+"eventfd","sys/eventfd.h","defined(CONFIG_EVENT_FD)","unsigned int","int"
 "exec","nuttx/binfmt/binfmt.h","!defined(CONFIG_BINFMT_DISABLE) && !defined(CONFIG_BUILD_KERNEL)","int","FAR const char *","FAR char * const *","FAR const struct symtab_s *","int"
 "execv","unistd.h","!defined(CONFIG_BINFMT_DISABLE) && defined(CONFIG_LIBC_EXECFUNCS)","int","FAR const char *","FAR char * const []|FAR char * const *"
 "exit","stdlib.h","","void","int"