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