LXR linux/drivers/video/fb

   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/vmalloc.h>
  17#include <linux/delay.h>
  18#include <linux/interrupt.h>
  19#include <linux/fb.h>
  20#include <linux/list.h>
  21
  22/* to support deferred IO */
  23#include <linux/rmap.h>
  24#include <linux/pagemap.h>
  25
  26struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
  27{
  28        void *screen_base = (void __force *) info->screen_base;
  29        struct page *page;
  30
  31        if (is_vmalloc_addr(screen_base + offs))
  32                page = vmalloc_to_page(screen_base + offs);
  33        else
  34                page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
  35
  36        return page;
  37}
  38
  39/* this is to find and return the vmalloc-ed fb pages */
  40static int fb_deferred_io_fault(struct vm_area_struct *vma,
  41                                struct vm_fault *vmf)
  42{
  43        unsigned long offset;
  44        struct page *page;
  45        struct fb_info *info = vma->vm_private_data;
  46
  47        offset = vmf->pgoff << PAGE_SHIFT;
  48        if (offset >= info->fix.smem_len)
  49                return VM_FAULT_SIGBUS;
  50
  51        page = fb_deferred_io_page(info, offset);
  52        if (!page)
  53                return VM_FAULT_SIGBUS;
  54
  55        get_page(page);
  56
  57        if (vma->vm_file)
  58                page->mapping = vma->vm_file->f_mapping;
  59        else
  60                printk(KERN_ERR "no mapping available\n");
  61
  62        BUG_ON(!page->mapping);
  63        page->index = vmf->pgoff;
  64
  65        vmf->page = page;
  66        return 0;
  67}
  68
  69int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
  70{
  71        struct fb_info *info = file->private_data;
  72
  73        /* Skip if deferred io is compiled-in but disabled on this fbdev */
  74        if (!info->fbdefio)
  75                return 0;
  76
  77        /* Kill off the delayed work */
  78        cancel_rearming_delayed_work(&info->deferred_work);
  79
  80        /* Run it immediately */
  81        return schedule_delayed_work(&info->deferred_work, 0);
  82}
  83EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
  84
  85/* vm_ops->page_mkwrite handler */
  86static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
  87                                  struct vm_fault *vmf)
  88{
  89        struct page *page = vmf->page;
  90        struct fb_info *info = vma->vm_private_data;
  91        struct fb_deferred_io *fbdefio = info->fbdefio;
  92        struct page *cur;
  93
  94        /* this is a callback we get when userspace first tries to
  95        write to the page. we schedule a workqueue. that workqueue
  96        will eventually mkclean the touched pages and execute the
  97        deferred framebuffer IO. then if userspace touches a page
  98        again, we repeat the same scheme */
  99
 100        /* protect against the workqueue changing the page list */
 101        mutex_lock(&fbdefio->lock);
 102
 103        /* we loop through the pagelist before adding in order
 104        to keep the pagelist sorted */
 105        list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 106                /* this check is to catch the case where a new
 107                process could start writing to the same page
 108                through a new pte. this new access can cause the
 109                mkwrite even when the original ps's pte is marked
 110                writable */
 111                if (unlikely(cur == page))
 112                        goto page_already_added;
 113                else if (cur->index > page->index)
 114                        break;
 115        }
 116
 117        list_add_tail(&page->lru, &cur->lru);
 118
 119page_already_added:
 120        mutex_unlock(&fbdefio->lock);
 121
 122        /* come back after delay to process the deferred IO */
 123        schedule_delayed_work(&info->deferred_work, fbdefio->delay);
 124        return 0;
 125}
 126
 127static const struct vm_operations_struct fb_deferred_io_vm_ops = {
 128        .fault          = fb_deferred_io_fault,
 129        .page_mkwrite   = fb_deferred_io_mkwrite,
 130};
 131
 132static int fb_deferred_io_set_page_dirty(struct page *page)
 133{
 134        if (!PageDirty(page))
 135                SetPageDirty(page);
 136        return 0;
 137}
 138
 139static const struct address_space_operations fb_deferred_io_aops = {
 140        .set_page_dirty = fb_deferred_io_set_page_dirty,
 141};
 142
 143static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
 144{
 145        vma->vm_ops = &fb_deferred_io_vm_ops;
 146        vma->vm_flags |= ( VM_RESERVED | VM_DONTEXPAND );
 147        if (!(info->flags & FBINFO_VIRTFB))
 148                vma->vm_flags |= VM_IO;
 149        vma->vm_private_data = info;
 150        return 0;
 151}
 152
 153/* workqueue callback */
 154static void fb_deferred_io_work(struct work_struct *work)
 155{
 156        struct fb_info *info = container_of(work, struct fb_info,
 157                                                deferred_work.work);
 158        struct list_head *node, *next;
 159        struct page *cur;
 160        struct fb_deferred_io *fbdefio = info->fbdefio;
 161
 162        /* here we mkclean the pages, then do all deferred IO */
 163        mutex_lock(&fbdefio->lock);
 164        list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 165                lock_page(cur);
 166                page_mkclean(cur);
 167                unlock_page(cur);
 168        }
 169
 170        /* driver's callback with pagelist */
 171        fbdefio->deferred_io(info, &fbdefio->pagelist);
 172
 173        /* clear the list */
 174        list_for_each_safe(node, next, &fbdefio->pagelist) {
 175                list_del(node);
 176        }
 177        mutex_unlock(&fbdefio->lock);
 178}
 179
 180void fb_deferred_io_init(struct fb_info *info)
 181{
 182        struct fb_deferred_io *fbdefio = info->fbdefio;
 183
 184        BUG_ON(!fbdefio);
 185        mutex_init(&fbdefio->lock);
 186        info->fbops->fb_mmap = fb_deferred_io_mmap;
 187        INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
 188        INIT_LIST_HEAD(&fbdefio->pagelist);
 189        if (fbdefio->delay == 0) /* set a default of 1 s */
 190                fbdefio->delay = HZ;
 191}
 192EXPORT_SYMBOL_GPL(fb_deferred_io_init);
 193
 194void fb_deferred_io_open(struct fb_info *info,
 195                         struct inode *inode,
 196                         struct file *file)
 197{
 198        file->f_mapping->a_ops = &fb_deferred_io_aops;
 199}
 200EXPORT_SYMBOL_GPL(fb_deferred_io_open);
 201
 202void fb_deferred_io_cleanup(struct fb_info *info)
 203{
 204        struct fb_deferred_io *fbdefio = info->fbdefio;
 205        struct page *page;
 206        int i;
 207
 208        BUG_ON(!fbdefio);
 209        cancel_delayed_work(&info->deferred_work);
 210        flush_scheduled_work();
 211
 212        /* clear out the mapping that we setup */
 213        for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
 214                page = fb_deferred_io_page(info, i);
 215                page->mapping = NULL;
 216        }
 217
 218        info->fbops->fb_mmap = NULL;
 219        mutex_destroy(&fbdefio->lock);
 220}
 221EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
 222
 223MODULE_LICENSE("GPL");
 224