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
27 /* this is to find and return the vmalloc-ed fb pages */
28 static int fb_deferred_io_fault(struct vm_area_struct *vma,
29 struct vm_fault *vmf)
30 {
31 unsigned long offset;
32 struct page *page;
33 struct fb_info *info = vma->vm_private_data;
34 /* info->screen_base is virtual memory */
35 void *screen_base = (void __force *) info->screen_base;
36
37 offset = vmf->pgoff << PAGE_SHIFT;
38 if (offset >= info->fix.smem_len)
39 return VM_FAULT_SIGBUS;
40
41 page = vmalloc_to_page(screen_base + offset);
42 if (!page)
43 return VM_FAULT_SIGBUS;
44
45 get_page(page);
46
47 if (vma->vm_file)
48 page->mapping = vma->vm_file->f_mapping;
49 else
50 printk(KERN_ERR "no mapping available\n");
51
52 BUG_ON(!page->mapping);
53 page->index = vmf->pgoff;
54
55 vmf->page = page;
56 return 0;
57 }
58
59 int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
60 {
61 struct fb_info *info = file->private_data;
62
63 /* Kill off the delayed work */
64 cancel_rearming_delayed_work(&info->deferred_work);
65
66 /* Run it immediately */
67 return schedule_delayed_work(&info->deferred_work, 0);
68 }
69 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
70
71 /* vm_ops->page_mkwrite handler */
72 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
73 struct page *page)
74 {
75 struct fb_info *info = vma->vm_private_data;
76 struct fb_deferred_io *fbdefio = info->fbdefio;
77
78 /* this is a callback we get when userspace first tries to
79 write to the page. we schedule a workqueue. that workqueue
80 will eventually mkclean the touched pages and execute the
81 deferred framebuffer IO. then if userspace touches a page
82 again, we repeat the same scheme */
83
84 /* protect against the workqueue changing the page list */
85 mutex_lock(&fbdefio->lock);
86 list_add(&page->lru, &fbdefio->pagelist);
87 mutex_unlock(&fbdefio->lock);
88
89 /* come back after delay to process the deferred IO */
90 schedule_delayed_work(&info->deferred_work, fbdefio->delay);
91 return 0;
92 }
93
94 static struct vm_operations_struct fb_deferred_io_vm_ops = {
95 .fault = fb_deferred_io_fault,
96 .page_mkwrite = fb_deferred_io_mkwrite,
97 };
98
99 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
100 {
101 vma->vm_ops = &fb_deferred_io_vm_ops;
102 vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
103 vma->vm_private_data = info;
104 return 0;
105 }
106
107 /* workqueue callback */
108 static void fb_deferred_io_work(struct work_struct *work)
109 {
110 struct fb_info *info = container_of(work, struct fb_info,
111 deferred_work.work);
112 struct list_head *node, *next;
113 struct page *cur;
114 struct fb_deferred_io *fbdefio = info->fbdefio;
115
116 /* here we mkclean the pages, then do all deferred IO */
117 mutex_lock(&fbdefio->lock);
118 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
119 lock_page(cur);
120 page_mkclean(cur);
121 unlock_page(cur);
122 }
123
124 /* driver's callback with pagelist */
125 fbdefio->deferred_io(info, &fbdefio->pagelist);
126
127 /* clear the list */
128 list_for_each_safe(node, next, &fbdefio->pagelist) {
129 list_del(node);
130 }
131 mutex_unlock(&fbdefio->lock);
132 }
133
134 void fb_deferred_io_init(struct fb_info *info)
135 {
136 struct fb_deferred_io *fbdefio = info->fbdefio;
137
138 BUG_ON(!fbdefio);
139 mutex_init(&fbdefio->lock);
140 info->fbops->fb_mmap = fb_deferred_io_mmap;
141 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
142 INIT_LIST_HEAD(&fbdefio->pagelist);
143 if (fbdefio->delay == 0) /* set a default of 1 s */
144 fbdefio->delay = HZ;
145 }
146 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
147
148 void fb_deferred_io_cleanup(struct fb_info *info)
149 {
150 void *screen_base = (void __force *) info->screen_base;
151 struct fb_deferred_io *fbdefio = info->fbdefio;
152 struct page *page;
153 int i;
154
155 BUG_ON(!fbdefio);
156 cancel_delayed_work(&info->deferred_work);
157 flush_scheduled_work();
158
159 /* clear out the mapping that we setup */
160 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
161 page = vmalloc_to_page(screen_base + i);
162 page->mapping = NULL;
163 }
164 }
165 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
166
167 MODULE_LICENSE("GPL");
168
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