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/*
* 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/slab.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>
/* 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;
/* info->screen_base is virtual memory */
void *screen_base = (void __force *) info->screen_base;
offset = vmf->pgoff << PAGE_SHIFT;
if (offset >= info->fix.smem_len)
return VM_FAULT_SIGBUS;
page = vmalloc_to_page(screen_base + 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, struct dentry *dentry, int datasync)
{
struct fb_info *info = file->private_data;
/* Kill off the delayed work */
cancel_rearming_delayed_work(&info->deferred_work);
/* Run it immediately */
return schedule_delayed_work(&info->deferred_work, 0);
}
EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
/* vm_ops->page_mkwrite handler */
static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
struct page *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 */
/* protect against the workqueue changing the page list */
mutex_lock(&fbdefio->lock);
/* 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 0;
}
static 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_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
vma->vm_ops = &fb_deferred_io_vm_ops;
vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
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_cleanup(struct fb_info *info)
{
void *screen_base = (void __force *) info->screen_base;
struct fb_deferred_io *fbdefio = info->fbdefio;
struct page *page;
int i;
BUG_ON(!fbdefio);
cancel_delayed_work(&info->deferred_work);
flush_scheduled_work();
/* clear out the mapping that we setup */
for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
page = vmalloc_to_page(screen_base + i);
page->mapping = NULL;
}
}
EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
MODULE_LICENSE("GPL");
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