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