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
  23 /* to support deferred IO */
  24 #include <linux/rmap.h>
  25 #include <linux/pagemap.h>
  26
  27 /* this is to find and return the vmalloc-ed fb pages */
  28 static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
  29                                         unsigned long vaddr, int *type)
  30 {
  31         unsigned long offset;
  32         struct page *page;
  33         struct fb_info *info = vma->vm_private_data;
  34         /* info->screen_base is in System RAM */
  35         void *screen_base = (void __force *) info->screen_base;
  36
  37         offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
  38         if (offset >= info->fix.smem_len)
  39                 return NOPAGE_SIGBUS;
  40
  41         page = vmalloc_to_page(screen_base + offset);
  42         if (!page)
  43                 return NOPAGE_OOM;
  44
  45         get_page(page);
  46         if (type)
  47                 *type = VM_FAULT_MINOR;
  48         return page;
  49 }
  50
  51 int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
  52 {
  53         struct fb_info *info = file->private_data;
  54
  55         /* Kill off the delayed work */
  56         cancel_rearming_delayed_work(&info->deferred_work);
  57
  58         /* Run it immediately */
  59         return schedule_delayed_work(&info->deferred_work, 0);
  60 }
  61 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
  62
  63 /* vm_ops->page_mkwrite handler */
  64 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
  65                                   struct page *page)
  66 {
  67         struct fb_info *info = vma->vm_private_data;
  68         struct fb_deferred_io *fbdefio = info->fbdefio;
  69
  70         /* this is a callback we get when userspace first tries to
  71         write to the page. we schedule a workqueue. that workqueue
  72         will eventually mkclean the touched pages and execute the
  73         deferred framebuffer IO. then if userspace touches a page
  74         again, we repeat the same scheme */
  75
  76         /* protect against the workqueue changing the page list */
  77         mutex_lock(&fbdefio->lock);
  78         list_add(&page->lru, &fbdefio->pagelist);
  79         mutex_unlock(&fbdefio->lock);
  80
  81         /* come back after delay to process the deferred IO */
  82         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
  83         return 0;
  84 }
  85
  86 static struct vm_operations_struct fb_deferred_io_vm_ops = {
  87         .nopage         = fb_deferred_io_nopage,
  88         .page_mkwrite   = fb_deferred_io_mkwrite,
  89 };
  90
  91 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
  92 {
  93         vma->vm_ops = &fb_deferred_io_vm_ops;
  94         vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
  95         vma->vm_private_data = info;
  96         return 0;
  97 }
  98
  99 /* workqueue callback */
 100 static void fb_deferred_io_work(struct work_struct *work)
 101 {
 102         struct fb_info *info = container_of(work, struct fb_info,
 103                                                 deferred_work.work);
 104         struct list_head *node, *next;
 105         struct page *cur;
 106         struct fb_deferred_io *fbdefio = info->fbdefio;
 107
 108         /* here we mkclean the pages, then do all deferred IO */
 109         mutex_lock(&fbdefio->lock);
 110         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 111                 lock_page(cur);
 112                 page_mkclean(cur);
 113                 unlock_page(cur);
 114         }
 115
 116         /* driver's callback with pagelist */
 117         fbdefio->deferred_io(info, &fbdefio->pagelist);
 118
 119         /* clear the list */
 120         list_for_each_safe(node, next, &fbdefio->pagelist) {
 121                 list_del(node);
 122         }
 123         mutex_unlock(&fbdefio->lock);
 124 }
 125
 126 void fb_deferred_io_init(struct fb_info *info)
 127 {
 128         struct fb_deferred_io *fbdefio = info->fbdefio;
 129
 130         BUG_ON(!fbdefio);
 131         mutex_init(&fbdefio->lock);
 132         info->fbops->fb_mmap = fb_deferred_io_mmap;
 133         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
 134         INIT_LIST_HEAD(&fbdefio->pagelist);
 135         if (fbdefio->delay == 0) /* set a default of 1 s */
 136                 fbdefio->delay = HZ;
 137 }
 138 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
 139
 140 void fb_deferred_io_cleanup(struct fb_info *info)
 141 {
 142         struct fb_deferred_io *fbdefio = info->fbdefio;
 143
 144         BUG_ON(!fbdefio);
 145         cancel_delayed_work(&info->deferred_work);
 146         flush_scheduled_work();
 147 }
 148 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
 149
 150 MODULE_LICENSE("GPL");