1 files changed, 245 insertions, 0 deletions
diff --git a/drivers/video/fbdev/fb_defio.c b/drivers/video/fbdev/fb_defio.c
new file mode 100644
index 0000000..900aa4e
--- /dev/null
+++ b/drivers/video/fbdev/fb_defio.c
@@ -0,0 +1,245 @@
+/*
+ *  linux/drivers/video/fb_defio.c
+ *
+ *  Copyright (C) 2006 Jaya Kumar
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/fb.h>
+#include <linux/list.h>
+
+/* to support deferred IO */
+#include <linux/rmap.h>
+#include <linux/pagemap.h>
+
+static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
+{
+	void *screen_base = (void __force *) info->screen_base;
+	struct page *page;
+
+	if (is_vmalloc_addr(screen_base + offs))
+		page = vmalloc_to_page(screen_base + offs);
+	else
+		page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
+
+	return page;
+}
+
+/* this is to find and return the vmalloc-ed fb pages */
+static int fb_deferred_io_fault(struct vm_area_struct *vma,
+				struct vm_fault *vmf)
+{
+	unsigned long offset;
+	struct page *page;
+	struct fb_info *info = vma->vm_private_data;
+
+	offset = vmf->pgoff << PAGE_SHIFT;
+	if (offset >= info->fix.smem_len)
+		return VM_FAULT_SIGBUS;
+
+	page = fb_deferred_io_page(info, offset);
+	if (!page)
+		return VM_FAULT_SIGBUS;
+
+	get_page(page);
+
+	if (vma->vm_file)
+		page->mapping = vma->vm_file->f_mapping;
+	else
+		printk(KERN_ERR "no mapping available\n");
+
+	BUG_ON(!page->mapping);
+	page->index = vmf->pgoff;
+
+	vmf->page = page;
+	return 0;
+}
+
+int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct fb_info *info = file->private_data;
+	struct inode *inode = file_inode(file);
+	int err = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (err)
+		return err;
+
+	/* Skip if deferred io is compiled-in but disabled on this fbdev */
+	if (!info->fbdefio)
+		return 0;
+
+	mutex_lock(&inode->i_mutex);
+	/* Kill off the delayed work */
+	cancel_delayed_work_sync(&info->deferred_work);
+
+	/* Run it immediately */
+	err = schedule_delayed_work(&info->deferred_work, 0);
+	mutex_unlock(&inode->i_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
+
+/* vm_ops->page_mkwrite handler */
+static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
+				  struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct fb_info *info = vma->vm_private_data;
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct page *cur;
+
+	/* this is a callback we get when userspace first tries to
+	write to the page. we schedule a workqueue. that workqueue
+	will eventually mkclean the touched pages and execute the
+	deferred framebuffer IO. then if userspace touches a page
+	again, we repeat the same scheme */
+
+	file_update_time(vma->vm_file);
+
+	/* protect against the workqueue changing the page list */
+	mutex_lock(&fbdefio->lock);
+
+	/* first write in this cycle, notify the driver */
+	if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
+		fbdefio->first_io(info);
+
+	/*
+	 * We want the page to remain locked from ->page_mkwrite until
+	 * the PTE is marked dirty to avoid page_mkclean() being called
+	 * before the PTE is updated, which would leave the page ignored
+	 * by defio.
+	 * Do this by locking the page here and informing the caller
+	 * about it with VM_FAULT_LOCKED.
+	 */
+	lock_page(page);
+
+	/* we loop through the pagelist before adding in order
+	to keep the pagelist sorted */
+	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
+		/* this check is to catch the case where a new
+		process could start writing to the same page
+		through a new pte. this new access can cause the
+		mkwrite even when the original ps's pte is marked
+		writable */
+		if (unlikely(cur == page))
+			goto page_already_added;
+		else if (cur->index > page->index)
+			break;
+	}
+
+	list_add_tail(&page->lru, &cur->lru);
+
+page_already_added:
+	mutex_unlock(&fbdefio->lock);
+
+	/* come back after delay to process the deferred IO */
+	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
+	return VM_FAULT_LOCKED;
+}
+
+static const struct vm_operations_struct fb_deferred_io_vm_ops = {
+	.fault		= fb_deferred_io_fault,
+	.page_mkwrite	= fb_deferred_io_mkwrite,
+};
+
+static int fb_deferred_io_set_page_dirty(struct page *page)
+{
+	if (!PageDirty(page))
+		SetPageDirty(page);
+	return 0;
+}
+
+static const struct address_space_operations fb_deferred_io_aops = {
+	.set_page_dirty = fb_deferred_io_set_page_dirty,
+};
+
+static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &fb_deferred_io_vm_ops;
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	if (!(info->flags & FBINFO_VIRTFB))
+		vma->vm_flags |= VM_IO;
+	vma->vm_private_data = info;
+	return 0;
+}
+
+/* workqueue callback */
+static void fb_deferred_io_work(struct work_struct *work)
+{
+	struct fb_info *info = container_of(work, struct fb_info,
+						deferred_work.work);
+	struct list_head *node, *next;
+	struct page *cur;
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	/* here we mkclean the pages, then do all deferred IO */
+	mutex_lock(&fbdefio->lock);
+	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
+		lock_page(cur);
+		page_mkclean(cur);
+		unlock_page(cur);
+	}
+
+	/* driver's callback with pagelist */
+	fbdefio->deferred_io(info, &fbdefio->pagelist);
+
+	/* clear the list */
+	list_for_each_safe(node, next, &fbdefio->pagelist) {
+		list_del(node);
+	}
+	mutex_unlock(&fbdefio->lock);
+}
+
+void fb_deferred_io_init(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	BUG_ON(!fbdefio);
+	mutex_init(&fbdefio->lock);
+	info->fbops->fb_mmap = fb_deferred_io_mmap;
+	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
+	INIT_LIST_HEAD(&fbdefio->pagelist);
+	if (fbdefio->delay == 0) /* set a default of 1 s */
+		fbdefio->delay = HZ;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_init);
+
+void fb_deferred_io_open(struct fb_info *info,
+			 struct inode *inode,
+			 struct file *file)
+{
+	file->f_mapping->a_ops = &fb_deferred_io_aops;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_open);
+
+void fb_deferred_io_cleanup(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct page *page;
+	int i;
+
+	BUG_ON(!fbdefio);
+	cancel_delayed_work_sync(&info->deferred_work);
+
+	/* clear out the mapping that we setup */
+	for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
+		page = fb_deferred_io_page(info, i);
+		page->mapping = NULL;
+	}
+
+	info->fbops->fb_mmap = NULL;
+	mutex_destroy(&fbdefio->lock);
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
+
+MODULE_LICENSE("GPL");