2 * linux/drivers/video/fb_defio.c
4 * Copyright (C) 2006 Jaya Kumar
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
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/errno.h>
14 #include <linux/string.h>
16 #include <linux/vmalloc.h>
17 #include <linux/delay.h>
18 #include <linux/interrupt.h>
20 #include <linux/list.h>
22 /* to support deferred IO */
23 #include <linux/rmap.h>
24 #include <linux/pagemap.h>
26 static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
28 void *screen_base = (void __force *) info->screen_base;
31 if (is_vmalloc_addr(screen_base + offs))
32 page = vmalloc_to_page(screen_base + offs);
34 page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
39 /* this is to find and return the vmalloc-ed fb pages */
40 static int fb_deferred_io_fault(struct vm_area_struct *vma,
45 struct fb_info *info = vma->vm_private_data;
47 offset = vmf->pgoff << PAGE_SHIFT;
48 if (offset >= info->fix.smem_len)
49 return VM_FAULT_SIGBUS;
51 page = fb_deferred_io_page(info, offset);
53 return VM_FAULT_SIGBUS;
58 page->mapping = vma->vm_file->f_mapping;
60 printk(KERN_ERR "no mapping available\n");
62 BUG_ON(!page->mapping);
63 page->index = vmf->pgoff;
69 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
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);
77 /* Skip if deferred io is compiled-in but disabled on this fbdev */
82 /* Kill off the delayed work */
83 cancel_delayed_work_sync(&info->deferred_work);
85 /* Run it immediately */
86 schedule_delayed_work(&info->deferred_work, 0);
91 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
93 /* vm_ops->page_mkwrite handler */
94 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
97 struct page *page = vmf->page;
98 struct fb_info *info = vma->vm_private_data;
99 struct fb_deferred_io *fbdefio = info->fbdefio;
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 */
108 file_update_time(vma->vm_file);
110 /* protect against the workqueue changing the page list */
111 mutex_lock(&fbdefio->lock);
113 /* first write in this cycle, notify the driver */
114 if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
115 fbdefio->first_io(info);
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
122 * Do this by locking the page here and informing the caller
123 * about it with VM_FAULT_LOCKED.
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
135 if (unlikely(cur == page))
136 goto page_already_added;
137 else if (cur->index > page->index)
141 list_add_tail(&page->lru, &cur->lru);
144 mutex_unlock(&fbdefio->lock);
146 /* come back after delay to process the deferred IO */
147 schedule_delayed_work(&info->deferred_work, fbdefio->delay);
148 return VM_FAULT_LOCKED;
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,
156 static int fb_deferred_io_set_page_dirty(struct page *page)
158 if (!PageDirty(page))
163 static const struct address_space_operations fb_deferred_io_aops = {
164 .set_page_dirty = fb_deferred_io_set_page_dirty,
167 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
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;
176 EXPORT_SYMBOL(fb_deferred_io_mmap);
178 /* workqueue callback */
179 static void fb_deferred_io_work(struct work_struct *work)
181 struct fb_info *info = container_of(work, struct fb_info,
183 struct list_head *node, *next;
185 struct fb_deferred_io *fbdefio = info->fbdefio;
187 /* here we mkclean the pages, then do all deferred IO */
188 mutex_lock(&fbdefio->lock);
189 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
195 /* driver's callback with pagelist */
196 fbdefio->deferred_io(info, &fbdefio->pagelist);
199 list_for_each_safe(node, next, &fbdefio->pagelist) {
202 mutex_unlock(&fbdefio->lock);
205 void fb_deferred_io_init(struct fb_info *info)
207 struct fb_deferred_io *fbdefio = info->fbdefio;
210 mutex_init(&fbdefio->lock);
211 info->fbops->fb_mmap = fb_deferred_io_mmap;
212 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
213 INIT_LIST_HEAD(&fbdefio->pagelist);
214 if (fbdefio->delay == 0) /* set a default of 1 s */
217 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
219 void fb_deferred_io_open(struct fb_info *info,
223 file->f_mapping->a_ops = &fb_deferred_io_aops;
225 EXPORT_SYMBOL_GPL(fb_deferred_io_open);
227 void fb_deferred_io_cleanup(struct fb_info *info)
229 struct fb_deferred_io *fbdefio = info->fbdefio;
234 cancel_delayed_work_sync(&info->deferred_work);
236 /* clear out the mapping that we setup */
237 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
238 page = fb_deferred_io_page(info, i);
239 page->mapping = NULL;
242 info->fbops->fb_mmap = NULL;
243 mutex_destroy(&fbdefio->lock);
245 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);