Squashed commit of the following:

drivers/video/fb.c:  Framebuffer driver is code complete but as of yet untested.
    drivers/video/fb.c:  Add framebuffer character device.  This is basically only the framework for the driver; a lot of logic is still missing.

drivers/video/Kconfig

@@ -3,6 +3,10 @@
 # see the file kconfig-language.txt in the NuttX tools repository.
 #
 
+config VIDEO_FB
+	bool "Framebuffer character driver"
+	default n
+
 config VIDEO_OV2640
 	bool "OV2640 camera chip"
 	default n

drivers/video/Make.defs

@@ -1,7 +1,7 @@
 ############################################################################
 # drivers/ov2640/Make.defs
 #
-#   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2013, 2017 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -37,6 +37,10 @@
 
 ifeq ($(CONFIG_VIDEO_DEVICES),y)
 
+ifeq ($(CONFIG_VIDEO_FB),y)
+  CSRCS += fb.c
+endif
+
 # These video drivers depend on I2C support
 
 ifeq ($(CONFIG_I2C),y)

include/nuttx/fs/ioctl.h

@@ -90,6 +90,7 @@
 #define _USBCBASE       (0x2500) /* USB-C controller ioctl commands */
 #define _MAC802154BASE  (0x2600) /* 802.15.4 MAC ioctl commands */
 #define _PWRBASE        (0x2700) /* Power-related ioctl commands */
+#define _FBIOCBASE      (0x2800) /* Frame buffer character driver ioctl commands */
 
 /* boardctl() commands share the same number space */
 
@@ -431,9 +432,14 @@
 
 /* Power-Related IOCTLs *****************************************************/
 
-#define _PWRIOCVALID(c)   (_IOC_TYPE(c)==_SMPS_BASE)
+#define _PWRIOCVALID(c)   (_IOC_TYPE(c)==_PWRBASE)
 #define _PWRIOC(nr)       _IOC(_PWRBASE,nr)
 
+/* Frame buffer character drivers *******************************************/
+
+#define _FBIOCVALID(c)   (_IOC_TYPE(c)==_FBIOCBASE)
+#define _FBIOC(nr)       _IOC(_FBIOCBASE,nr)
+
 /* boardctl() command definitions *******************************************/
 
 #define _BOARDIOCVALID(c) (_IOC_TYPE(c)==_BOARDBASE)

include/nuttx/video/fb.h

@@ -42,6 +42,7 @@
 
 #include <nuttx/config.h>
 #include <stdint.h>
+#include <nuttx/fs/ioctl.h>
 
 /****************************************************************************
  * Pre-processor definitions
@@ -190,6 +191,27 @@
 #define FB_CUR_XOR         0x10        /* Use XOR vs COPY ROP on image */
 #endif
 
+/* FB character driver IOCTL commands ***************************************/
+
+/* ioctls */
+
+#define FBIOGET_VIDEOINFO  _FBIOC(0x0001)  /* Get color plane info */
+                                           /* Argument: writable struct fb_videoinfo_s */
+#define FBIOGET_PLANEINFO  _FBIOC(0x0002)  /* Get video plane info */
+                                           /* Argument: writable struct fb_planeinfo_s */
+#ifdef CONFIG_FB_CMAP
+#  define FBIOGET_CMAP     _FBIOC(0x0003)  /* Get RGB color mapping */
+                                           /* Argument: writable struct fb_cmap_s */
+#  define FBIOPUT_CMAP     _FBIOC(0x0004)  /* Put RGB color mapping */
+                                           /* Argument: read-only struct fb_cmap_s */
+#endif
+#ifdef CONFIG_FB_HWCURSOR
+#  define FBIOGET_CURSOR   _FBIOC(0x0005)  /* Get cursor attributes */
+                                           /* Argument: writable struct fb_cursorattrib_s */
+#  define FBIOPUT_CURSOR   _FBIOC(0x0006)  /* Set cursor attibutes */
+                                           /* Argument: read-only struct fb_setcursor_s */
+#endif
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -307,8 +329,8 @@ struct fb_setcursor_s
 };
 #endif
 
-/* The framebuffer "driver" under NuttX is not a driver at all, but simply
- * a driver "object" that is accessed through the following vtable:
+/* The framebuffer "object" is accessed through within the OS via
+ * the following vtable:
  */
 
 struct fb_vtable_s
@@ -322,22 +344,22 @@ struct fb_vtable_s
   int (*getplaneinfo)(FAR struct fb_vtable_s *vtable, int planeno,
                       FAR struct fb_planeinfo_s *pinfo);
 
+#ifdef CONFIG_FB_CMAP
   /* The following are provided only if the video hardware supports RGB
    * color mapping
    */
 
-#ifdef CONFIG_FB_CMAP
   int (*getcmap)(FAR struct fb_vtable_s *vtable,
                  FAR struct fb_cmap_s *cmap);
   int (*putcmap)(FAR struct fb_vtable_s *vtable,
                  FAR const struct fb_cmap_s *cmap);
 #endif
 
+#ifdef CONFIG_FB_HWCURSOR
   /* The following are provided only if the video hardware supports a
    * hardware cursor.
    */
 
-#ifdef CONFIG_FB_HWCURSOR
   int (*getcursor)(FAR struct fb_vtable_s *vtable,
                    FAR struct fb_cursorattrib_s *attrib);
   int (*setcursor)(FAR struct fb_vtable_s *vtable,