fbdev: mm: Deferred IO support
This implements deferred IO support in fbdev. Deferred IO is a way to delay
and repurpose IO. This implementation is done using mm's page_mkwrite and
page_mkclean hooks in order to detect, delay and then rewrite IO. This
functionality is used by hecubafb.
[adaplas]
This is useful for graphics hardware with no directly addressable/mappable
framebuffer. Implementing this will allow the "framebuffer" to be accesible
from user space via mmap().
Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/fb.h b/include/linux/fb.h
index be913ec..8a8255b 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -561,6 +561,16 @@
void (*readio) (struct fb_info *info, void *dst, void __iomem *src, unsigned int size);
};
+#ifdef CONFIG_FB_DEFERRED_IO
+struct fb_deferred_io {
+ /* delay between mkwrite and deferred handler */
+ unsigned long delay;
+ struct mutex lock; /* mutex that protects the page list */
+ struct list_head pagelist; /* list of touched pages */
+ /* callback */
+ void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);
+};
+#endif
/*
* Frame buffer operations
@@ -778,6 +788,10 @@
struct mutex bl_curve_mutex;
u8 bl_curve[FB_BACKLIGHT_LEVELS];
#endif
+#ifdef CONFIG_FB_DEFERRED_IO
+ struct delayed_work deferred_work;
+ struct fb_deferred_io *fbdefio;
+#endif
struct fb_ops *fbops;
struct device *device; /* This is the parent */
@@ -913,6 +927,12 @@
}
}
+#ifdef CONFIG_FB_DEFERRED_IO
+/* drivers/video/fb_defio.c */
+extern void fb_deferred_io_init(struct fb_info *info);
+extern void fb_deferred_io_cleanup(struct fb_info *info);
+#endif
+
/* drivers/video/fbsysfs.c */
extern struct fb_info *framebuffer_alloc(size_t size, struct device *dev);
extern void framebuffer_release(struct fb_info *info);