drivers/video/fb_defio.c

   1 /*
   2  *  linux/drivers/video/fb_defio.c
   3  *
   4  *  Copyright (C) 2006 Jaya Kumar
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file COPYING in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/errno.h>
  14 #include <linux/string.h>
  15 #include <linux/mm.h>
  16 #include <linux/slab.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/delay.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/fb.h>
  21 #include <linux/list.h>
  22 #include <asm/uaccess.h>
  23
  24 /* to support deferred IO */
  25 #include <linux/rmap.h>
  26 #include <linux/pagemap.h>
  27
  28 /* this is to find and return the vmalloc-ed fb pages */
  29 static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
  30                                         unsigned long vaddr, int *type)
  31 {
  32         unsigned long offset;
  33         struct page *page;
  34         struct fb_info *info = vma->vm_private_data;
  35
  36         offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
  37         if (offset >= info->fix.smem_len)
  38                 return NOPAGE_SIGBUS;
  39
  40         page = vmalloc_to_page(info->screen_base + offset);
  41         if (!page)
  42                 return NOPAGE_OOM;
  43
  44         get_page(page);
  45         if (type)
  46                 *type = VM_FAULT_MINOR;
  47         return page;
  48 }
  49
  50 /* vm_ops->page_mkwrite handler */
  51 int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
  52                                         struct page *page)
  53 {
  54         struct fb_info *info = vma->vm_private_data;
  55         struct fb_deferred_io *fbdefio = info->fbdefio;
  56
  57         /* this is a callback we get when userspace first tries to
  58         write to the page. we schedule a workqueue. that workqueue
  59         will eventually mkclean the touched pages and execute the
  60         deferred framebuffer IO. then if userspace touches a page
  61         again, we repeat the same scheme */
  62
  63         /* protect against the workqueue changing the page list */
  64         mutex_lock(&fbdefio->lock);
  65         list_add(&page->lru, &fbdefio->pagelist);
  66         mutex_unlock(&fbdefio->lock);
  67
  68         /* come back after delay to process the deferred IO */
  69         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
  70         return 0;
  71 }
  72
  73 static struct vm_operations_struct fb_deferred_io_vm_ops = {
  74         .nopage         = fb_deferred_io_nopage,
  75         .page_mkwrite   = fb_deferred_io_mkwrite,
  76 };
  77
  78 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
  79 {
  80         vma->vm_ops = &fb_deferred_io_vm_ops;
  81         vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
  82         vma->vm_private_data = info;
  83         return 0;
  84 }
  85
  86 /* workqueue callback */
  87 static void fb_deferred_io_work(struct work_struct *work)
  88 {
  89         struct fb_info *info = container_of(work, struct fb_info,
  90                                                 deferred_work.work);
  91         struct list_head *node, *next;
  92         struct page *cur;
  93         struct fb_deferred_io *fbdefio = info->fbdefio;
  94
  95         /* here we mkclean the pages, then do all deferred IO */
  96         mutex_lock(&fbdefio->lock);
  97         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
  98                 lock_page(cur);
  99                 page_mkclean(cur);
 100                 unlock_page(cur);
 101         }
 102
 103         /* driver's callback with pagelist */
 104         fbdefio->deferred_io(info, &fbdefio->pagelist);
 105
 106         /* clear the list */
 107         list_for_each_safe(node, next, &fbdefio->pagelist) {
 108                 list_del(node);
 109         }
 110         mutex_unlock(&fbdefio->lock);
 111 }
 112
 113 void fb_deferred_io_init(struct fb_info *info)
 114 {
 115         struct fb_deferred_io *fbdefio = info->fbdefio;
 116
 117         BUG_ON(!fbdefio);
 118         mutex_init(&fbdefio->lock);
 119         info->fbops->fb_mmap = fb_deferred_io_mmap;
 120         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
 121         INIT_LIST_HEAD(&fbdefio->pagelist);
 122         if (fbdefio->delay == 0) /* set a default of 1 s */
 123                 fbdefio->delay = HZ;
 124 }
 125 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
 126
 127 void fb_deferred_io_cleanup(struct fb_info *info)
 128 {
 129         struct fb_deferred_io *fbdefio = info->fbdefio;
 130
 131         BUG_ON(!fbdefio);
 132         cancel_delayed_work(&info->deferred_work);
 133         flush_scheduled_work();
 134 }
 135 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
 136
 137 MODULE_LICENSE("GPL");