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 vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
44 struct fb_info *info = vmf->vma->vm_private_data;
46 offset = vmf->pgoff << PAGE_SHIFT;
47 if (offset >= info->fix.smem_len)
48 return VM_FAULT_SIGBUS;
50 page = fb_deferred_io_page(info, offset);
52 return VM_FAULT_SIGBUS;
55 page->index = vmf->pgoff;
61 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
63 struct fb_info *info = file->private_data;
64 struct inode *inode = file_inode(file);
65 int err = file_write_and_wait_range(file, start, end);
69 /* Skip if deferred io is compiled-in but disabled on this fbdev */
74 /* Kill off the delayed work */
75 cancel_delayed_work_sync(&info->deferred_work);
77 /* Run it immediately */
78 schedule_delayed_work(&info->deferred_work, 0);
83 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
85 /* vm_ops->page_mkwrite handler */
86 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)
88 struct page *page = vmf->page;
89 struct fb_info *info = vmf->vma->vm_private_data;
90 struct fb_deferred_io *fbdefio = info->fbdefio;
93 /* this is a callback we get when userspace first tries to
94 write to the page. we schedule a workqueue. that workqueue
95 will eventually mkclean the touched pages and execute the
96 deferred framebuffer IO. then if userspace touches a page
97 again, we repeat the same scheme */
99 file_update_time(vmf->vma->vm_file);
101 /* protect against the workqueue changing the page list */
102 mutex_lock(&fbdefio->lock);
104 /* first write in this cycle, notify the driver */
105 if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
106 fbdefio->first_io(info);
109 * We want the page to remain locked from ->page_mkwrite until
110 * the PTE is marked dirty to avoid page_mkclean() being called
111 * before the PTE is updated, which would leave the page ignored
113 * Do this by locking the page here and informing the caller
114 * about it with VM_FAULT_LOCKED.
118 /* we loop through the pagelist before adding in order
119 to keep the pagelist sorted */
120 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
121 /* this check is to catch the case where a new
122 process could start writing to the same page
123 through a new pte. this new access can cause the
124 mkwrite even when the original ps's pte is marked
126 if (unlikely(cur == page))
127 goto page_already_added;
128 else if (cur->index > page->index)
132 list_add_tail(&page->lru, &cur->lru);
135 mutex_unlock(&fbdefio->lock);
137 /* come back after delay to process the deferred IO */
138 schedule_delayed_work(&info->deferred_work, fbdefio->delay);
139 return VM_FAULT_LOCKED;
142 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
143 .fault = fb_deferred_io_fault,
144 .page_mkwrite = fb_deferred_io_mkwrite,
147 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
149 vma->vm_ops = &fb_deferred_io_vm_ops;
150 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
151 if (!(info->flags & FBINFO_VIRTFB))
152 vma->vm_flags |= VM_IO;
153 vma->vm_private_data = info;
157 /* workqueue callback */
158 static void fb_deferred_io_work(struct work_struct *work)
160 struct fb_info *info = container_of(work, struct fb_info,
162 struct list_head *node, *next;
164 struct fb_deferred_io *fbdefio = info->fbdefio;
166 /* here we mkclean the pages, then do all deferred IO */
167 mutex_lock(&fbdefio->lock);
168 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
174 /* driver's callback with pagelist */
175 fbdefio->deferred_io(info, &fbdefio->pagelist);
178 list_for_each_safe(node, next, &fbdefio->pagelist) {
181 mutex_unlock(&fbdefio->lock);
184 void fb_deferred_io_init(struct fb_info *info)
186 struct fb_deferred_io *fbdefio = info->fbdefio;
189 mutex_init(&fbdefio->lock);
190 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
191 INIT_LIST_HEAD(&fbdefio->pagelist);
192 if (fbdefio->delay == 0) /* set a default of 1 s */
195 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
197 void fb_deferred_io_cleanup(struct fb_info *info)
199 struct fb_deferred_io *fbdefio = info->fbdefio;
202 cancel_delayed_work_sync(&info->deferred_work);
203 mutex_destroy(&fbdefio->lock);
205 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);