drivers/video/fbdev/core/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/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
  26 static struct 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 */
  40 static 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
  69 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  70 {
  71         struct fb_info *info = file->private_data;
  72         struct inode *inode = file_inode(file);
  73         int err = filemap_write_and_wait_range(inode->i_mapping, start, end);
  74         if (err)
  75                 return err;
  76
  77         /* Skip if deferred io is compiled-in but disabled on this fbdev */
  78         if (!info->fbdefio)
  79                 return 0;
  80
  81         mutex_lock(&inode->i_mutex);
  82         /* Kill off the delayed work */
  83         cancel_delayed_work_sync(&info->deferred_work);
  84
  85         /* Run it immediately */
  86         schedule_delayed_work(&info->deferred_work, 0);
  87         mutex_unlock(&inode->i_mutex);
  88
  89         return 0;
  90 }
  91 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
  92
  93 /* vm_ops->page_mkwrite handler */
  94 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
  95                                   struct vm_fault *vmf)
  96 {
  97         struct page *page = vmf->page;
  98         struct fb_info *info = vma->vm_private_data;
  99         struct fb_deferred_io *fbdefio = info->fbdefio;
 100         struct page *cur;
 101
 102         /* this is a callback we get when userspace first tries to
 103         write to the page. we schedule a workqueue. that workqueue
 104         will eventually mkclean the touched pages and execute the
 105         deferred framebuffer IO. then if userspace touches a page
 106         again, we repeat the same scheme */
 107
 108         file_update_time(vma->vm_file);
 109
 110         /* protect against the workqueue changing the page list */
 111         mutex_lock(&fbdefio->lock);
 112
 113         /* first write in this cycle, notify the driver */
 114         if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
 115                 fbdefio->first_io(info);
 116
 117         /*
 118          * We want the page to remain locked from ->page_mkwrite until
 119          * the PTE is marked dirty to avoid page_mkclean() being called
 120          * before the PTE is updated, which would leave the page ignored
 121          * by defio.
 122          * Do this by locking the page here and informing the caller
 123          * about it with VM_FAULT_LOCKED.
 124          */
 125         lock_page(page);
 126
 127         /* we loop through the pagelist before adding in order
 128         to keep the pagelist sorted */
 129         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 130                 /* this check is to catch the case where a new
 131                 process could start writing to the same page
 132                 through a new pte. this new access can cause the
 133                 mkwrite even when the original ps's pte is marked
 134                 writable */
 135                 if (unlikely(cur == page))
 136                         goto page_already_added;
 137                 else if (cur->index > page->index)
 138                         break;
 139         }
 140
 141         list_add_tail(&page->lru, &cur->lru);
 142
 143 page_already_added:
 144         mutex_unlock(&fbdefio->lock);
 145
 146         /* come back after delay to process the deferred IO */
 147         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
 148         return VM_FAULT_LOCKED;
 149 }
 150
 151 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
 152         .fault          = fb_deferred_io_fault,
 153         .page_mkwrite   = fb_deferred_io_mkwrite,
 154 };
 155
 156 static int fb_deferred_io_set_page_dirty(struct page *page)
 157 {
 158         if (!PageDirty(page))
 159                 SetPageDirty(page);
 160         return 0;
 161 }
 162
 163 static const struct address_space_operations fb_deferred_io_aops = {
 164         .set_page_dirty = fb_deferred_io_set_page_dirty,
 165 };
 166
 167 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
 168 {
 169         vma->vm_ops = &fb_deferred_io_vm_ops;
 170         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 171         if (!(info->flags & FBINFO_VIRTFB))
 172                 vma->vm_flags |= VM_IO;
 173         vma->vm_private_data = info;
 174         return 0;
 175 }
 176
 177 /* workqueue callback */
 178 static void fb_deferred_io_work(struct work_struct *work)
 179 {
 180         struct fb_info *info = container_of(work, struct fb_info,
 181                                                 deferred_work.work);
 182         struct list_head *node, *next;
 183         struct page *cur;
 184         struct fb_deferred_io *fbdefio = info->fbdefio;
 185
 186         /* here we mkclean the pages, then do all deferred IO */
 187         mutex_lock(&fbdefio->lock);
 188         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 189                 lock_page(cur);
 190                 page_mkclean(cur);
 191                 unlock_page(cur);
 192         }
 193
 194         /* driver's callback with pagelist */
 195         fbdefio->deferred_io(info, &fbdefio->pagelist);
 196
 197         /* clear the list */
 198         list_for_each_safe(node, next, &fbdefio->pagelist) {
 199                 list_del(node);
 200         }
 201         mutex_unlock(&fbdefio->lock);
 202 }
 203
 204 void fb_deferred_io_init(struct fb_info *info)
 205 {
 206         struct fb_deferred_io *fbdefio = info->fbdefio;
 207
 208         BUG_ON(!fbdefio);
 209         mutex_init(&fbdefio->lock);
 210         info->fbops->fb_mmap = fb_deferred_io_mmap;
 211         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
 212         INIT_LIST_HEAD(&fbdefio->pagelist);
 213         if (fbdefio->delay == 0) /* set a default of 1 s */
 214                 fbdefio->delay = HZ;
 215 }
 216 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
 217
 218 void fb_deferred_io_open(struct fb_info *info,
 219                          struct inode *inode,
 220                          struct file *file)
 221 {
 222         file->f_mapping->a_ops = &fb_deferred_io_aops;
 223 }
 224 EXPORT_SYMBOL_GPL(fb_deferred_io_open);
 225
 226 void fb_deferred_io_cleanup(struct fb_info *info)
 227 {
 228         struct fb_deferred_io *fbdefio = info->fbdefio;
 229         struct page *page;
 230         int i;
 231
 232         BUG_ON(!fbdefio);
 233         cancel_delayed_work_sync(&info->deferred_work);
 234
 235         /* clear out the mapping that we setup */
 236         for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
 237                 page = fb_deferred_io_page(info, i);
 238                 page->mapping = NULL;
 239         }
 240
 241         info->fbops->fb_mmap = NULL;
 242         mutex_destroy(&fbdefio->lock);
 243 }
 244 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
 245
 246 MODULE_LICENSE("GPL");