1 files changed, 347 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
new file mode 100644
index 000000000..49883c801
--- /dev/null
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -0,0 +1,347 @@
+/*
+ *  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;
+}
+
+static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info *info,
+								 unsigned long offset,
+								 struct page *page)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct list_head *pos = &fbdefio->pagereflist;
+	unsigned long pgoff = offset >> PAGE_SHIFT;
+	struct fb_deferred_io_pageref *pageref, *cur;
+
+	if (WARN_ON_ONCE(pgoff >= info->npagerefs))
+		return NULL; /* incorrect allocation size */
+
+	/* 1:1 mapping between pageref and page offset */
+	pageref = &info->pagerefs[pgoff];
+
+	/*
+	 * 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 a call to .page_mkwrite even if the original process'
+	 * PTE is marked writable.
+	 */
+	if (!list_empty(&pageref->list))
+		goto pageref_already_added;
+
+	pageref->page = page;
+	pageref->offset = pgoff << PAGE_SHIFT;
+
+	if (unlikely(fbdefio->sort_pagereflist)) {
+		/*
+		 * We loop through the list of pagerefs before adding in
+		 * order to keep the pagerefs sorted. This has significant
+		 * overhead of O(n^2) with n being the number of written
+		 * pages. If possible, drivers should try to work with
+		 * unsorted page lists instead.
+		 */
+		list_for_each_entry(cur, &fbdefio->pagereflist, list) {
+			if (cur->offset > pageref->offset)
+				break;
+		}
+		pos = &cur->list;
+	}
+
+	list_add_tail(&pageref->list, pos);
+
+pageref_already_added:
+	return pageref;
+}
+
+static void fb_deferred_io_pageref_put(struct fb_deferred_io_pageref *pageref,
+				       struct fb_info *info)
+{
+	list_del_init(&pageref->list);
+}
+
+/* this is to find and return the vmalloc-ed fb pages */
+static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
+{
+	unsigned long offset;
+	struct page *page;
+	struct fb_info *info = vmf->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 (vmf->vma->vm_file)
+		page->mapping = vmf->vma->vm_file->f_mapping;
+	else
+		printk(KERN_ERR "no mapping available\n");
+
+	BUG_ON(!page->mapping);
+	page->index = vmf->pgoff; /* for page_mkclean() */
+
+	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 = file_write_and_wait_range(file, start, end);
+	if (err)
+		return err;
+
+	/* Skip if deferred io is compiled-in but disabled on this fbdev */
+	if (!info->fbdefio)
+		return 0;
+
+	inode_lock(inode);
+	flush_delayed_work(&info->deferred_work);
+	inode_unlock(inode);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
+
+/*
+ * Adds a page to the dirty list. Call this from struct
+ * vm_operations_struct.page_mkwrite.
+ */
+static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset,
+					    struct page *page)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_pageref *pageref;
+	vm_fault_t ret;
+
+	/* 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->pagereflist))
+		fbdefio->first_io(info);
+
+	pageref = fb_deferred_io_pageref_get(info, offset, page);
+	if (WARN_ON_ONCE(!pageref)) {
+		ret = VM_FAULT_OOM;
+		goto err_mutex_unlock;
+	}
+
+	/*
+	 * 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(pageref->page);
+
+	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;
+
+err_mutex_unlock:
+	mutex_unlock(&fbdefio->lock);
+	return ret;
+}
+
+/*
+ * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O
+ * @fb_info: The fbdev info structure
+ * @vmf: The VM fault
+ *
+ * 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.
+ *
+ * Returns:
+ * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise.
+ */
+static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf)
+{
+	unsigned long offset = vmf->address - vmf->vma->vm_start;
+	struct page *page = vmf->page;
+
+	file_update_time(vmf->vma->vm_file);
+
+	return fb_deferred_io_track_page(info, offset, page);
+}
+
+/* vm_ops->page_mkwrite handler */
+static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
+{
+	struct fb_info *info = vmf->vma->vm_private_data;
+
+	return fb_deferred_io_page_mkwrite(info, vmf);
+}
+
+static const struct vm_operations_struct fb_deferred_io_vm_ops = {
+	.fault		= fb_deferred_io_fault,
+	.page_mkwrite	= fb_deferred_io_mkwrite,
+};
+
+static const struct address_space_operations fb_deferred_io_aops = {
+	.dirty_folio	= noop_dirty_folio,
+};
+
+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;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_mmap);
+
+/* 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 fb_deferred_io_pageref *pageref, *next;
+	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(pageref, &fbdefio->pagereflist, list) {
+		struct page *cur = pageref->page;
+		lock_page(cur);
+		page_mkclean(cur);
+		unlock_page(cur);
+	}
+
+	/* driver's callback with pagereflist */
+	fbdefio->deferred_io(info, &fbdefio->pagereflist);
+
+	/* clear the list */
+	list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list)
+		fb_deferred_io_pageref_put(pageref, info);
+
+	mutex_unlock(&fbdefio->lock);
+}
+
+int fb_deferred_io_init(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_pageref *pagerefs;
+	unsigned long npagerefs, i;
+	int ret;
+
+	BUG_ON(!fbdefio);
+
+	if (WARN_ON(!info->fix.smem_len))
+		return -EINVAL;
+
+	mutex_init(&fbdefio->lock);
+	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
+	INIT_LIST_HEAD(&fbdefio->pagereflist);
+	if (fbdefio->delay == 0) /* set a default of 1 s */
+		fbdefio->delay = HZ;
+
+	npagerefs = DIV_ROUND_UP(info->fix.smem_len, PAGE_SIZE);
+
+	/* alloc a page ref for each page of the display memory */
+	pagerefs = kvcalloc(npagerefs, sizeof(*pagerefs), GFP_KERNEL);
+	if (!pagerefs) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	for (i = 0; i < npagerefs; ++i)
+		INIT_LIST_HEAD(&pagerefs[i].list);
+	info->npagerefs = npagerefs;
+	info->pagerefs = pagerefs;
+
+	return 0;
+
+err:
+	mutex_destroy(&fbdefio->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_init);
+
+void fb_deferred_io_open(struct fb_info *info,
+			 struct inode *inode,
+			 struct file *file)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	file->f_mapping->a_ops = &fb_deferred_io_aops;
+	fbdefio->open_count++;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_open);
+
+static void fb_deferred_io_lastclose(struct fb_info *info)
+{
+	struct page *page;
+	int i;
+
+	flush_delayed_work(&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;
+	}
+}
+
+void fb_deferred_io_release(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	if (!--fbdefio->open_count)
+		fb_deferred_io_lastclose(info);
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_release);
+
+void fb_deferred_io_cleanup(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	fb_deferred_io_lastclose(info);
+
+	kvfree(info->pagerefs);
+	mutex_destroy(&fbdefio->lock);
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);