tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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#include <asm/uaccess.h>
23
24/* to support deferred IO */
25#include <linux/rmap.h>
26#include <linux/pagemap.h>
27
28/* this is to find and return the vmalloc-ed fb pages */
29static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
30 unsigned long vaddr, int *type)
31{
32 unsigned long offset;
33 struct page *page;
34 struct fb_info *info = vma->vm_private_data;
35 /* info->screen_base is in System RAM */
36 void *screen_base = (void __force *) info->screen_base;
37
38 offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
39 if (offset >= info->fix.smem_len)
40 return NOPAGE_SIGBUS;
41
42 page = vmalloc_to_page(screen_base + offset);
43 if (!page)
44 return NOPAGE_OOM;
45
46 get_page(page);
47 if (type)
48 *type = VM_FAULT_MINOR;
49 return page;
50}
51
52int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
53{
54 struct fb_info *info = file->private_data;
55
56 /* Kill off the delayed work */
57 cancel_rearming_delayed_work(&info->deferred_work);
58
59 /* Run it immediately */
60 return schedule_delayed_work(&info->deferred_work, 0);
61}
62EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
63
64/* vm_ops->page_mkwrite handler */
65static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
66 struct page *page)
67{
68 struct fb_info *info = vma->vm_private_data;
69 struct fb_deferred_io *fbdefio = info->fbdefio;
70
71 /* this is a callback we get when userspace first tries to
72 write to the page. we schedule a workqueue. that workqueue
73 will eventually mkclean the touched pages and execute the
74 deferred framebuffer IO. then if userspace touches a page
75 again, we repeat the same scheme */
76
77 /* protect against the workqueue changing the page list */
78 mutex_lock(&fbdefio->lock);
79 list_add(&page->lru, &fbdefio->pagelist);
80 mutex_unlock(&fbdefio->lock);
81
82 /* come back after delay to process the deferred IO */
83 schedule_delayed_work(&info->deferred_work, fbdefio->delay);
84 return 0;
85}
86
87static struct vm_operations_struct fb_deferred_io_vm_ops = {
88 .nopage = fb_deferred_io_nopage,
89 .page_mkwrite = fb_deferred_io_mkwrite,
90};
91
92static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
93{
94 vma->vm_ops = &fb_deferred_io_vm_ops;
95 vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
96 vma->vm_private_data = info;
97 return 0;
98}
99
100/* workqueue callback */
101static void fb_deferred_io_work(struct work_struct *work)
102{
103 struct fb_info *info = container_of(work, struct fb_info,
104 deferred_work.work);
105 struct list_head *node, *next;
106 struct page *cur;
107 struct fb_deferred_io *fbdefio = info->fbdefio;
108
109 /* here we mkclean the pages, then do all deferred IO */
110 mutex_lock(&fbdefio->lock);
111 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
112 lock_page(cur);
113 page_mkclean(cur);
114 unlock_page(cur);
115 }
116
117 /* driver's callback with pagelist */
118 fbdefio->deferred_io(info, &fbdefio->pagelist);
119
120 /* clear the list */
121 list_for_each_safe(node, next, &fbdefio->pagelist) {
122 list_del(node);
123 }
124 mutex_unlock(&fbdefio->lock);
125}
126
127void fb_deferred_io_init(struct fb_info *info)
128{
129 struct fb_deferred_io *fbdefio = info->fbdefio;
130
131 BUG_ON(!fbdefio);
132 mutex_init(&fbdefio->lock);
133 info->fbops->fb_mmap = fb_deferred_io_mmap;
134 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
135 INIT_LIST_HEAD(&fbdefio->pagelist);
136 if (fbdefio->delay == 0) /* set a default of 1 s */
137 fbdefio->delay = HZ;
138}
139EXPORT_SYMBOL_GPL(fb_deferred_io_init);
140
141void fb_deferred_io_cleanup(struct fb_info *info)
142{
143 struct fb_deferred_io *fbdefio = info->fbdefio;
144
145 BUG_ON(!fbdefio);
146 cancel_delayed_work(&info->deferred_work);
147 flush_scheduled_work();
148}
149EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
150
151MODULE_LICENSE("GPL");