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