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
23/* to support deferred IO */
24#include <linux/rmap.h>
25#include <linux/pagemap.h>
26
27struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
28{
29 void *screen_base = (void __force *) info->screen_base;
30 struct page *page;
31
32 if (is_vmalloc_addr(screen_base + offs))
33 page = vmalloc_to_page(screen_base + offs);
34 else
35 page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
36
37 return page;
38}
39
40/* this is to find and return the vmalloc-ed fb pages */
41static int fb_deferred_io_fault(struct vm_area_struct *vma,
42 struct vm_fault *vmf)
43{
44 unsigned long offset;
45 struct page *page;
46 struct fb_info *info = vma->vm_private_data;
47
48 offset = vmf->pgoff << PAGE_SHIFT;
49 if (offset >= info->fix.smem_len)
50 return VM_FAULT_SIGBUS;
51
52 page = fb_deferred_io_page(info, offset);
53 if (!page)
54 return VM_FAULT_SIGBUS;
55
56 get_page(page);
57
58 if (vma->vm_file)
59 page->mapping = vma->vm_file->f_mapping;
60 else
61 printk(KERN_ERR "no mapping available\n");
62
63 BUG_ON(!page->mapping);
64 page->index = vmf->pgoff;
65
66 vmf->page = page;
67 return 0;
68}
69
70int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
71{
72 struct fb_info *info = file->private_data;
73
74 /* Skip if deferred io is compiled-in but disabled on this fbdev */
75 if (!info->fbdefio)
76 return 0;
77
78 /* Kill off the delayed work */
79 cancel_rearming_delayed_work(&info->deferred_work);
80
81 /* Run it immediately */
82 return schedule_delayed_work(&info->deferred_work, 0);
83}
84EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
85
86/* vm_ops->page_mkwrite handler */
87static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
88 struct vm_fault *vmf)
89{
90 struct page *page = vmf->page;
91 struct fb_info *info = vma->vm_private_data;
92 struct fb_deferred_io *fbdefio = info->fbdefio;
93 struct page *cur;
94
95 /* this is a callback we get when userspace first tries to
96 write to the page. we schedule a workqueue. that workqueue
97 will eventually mkclean the touched pages and execute the
98 deferred framebuffer IO. then if userspace touches a page
99 again, we repeat the same scheme */
100
101 /* protect against the workqueue changing the page list */
102 mutex_lock(&fbdefio->lock);
103
104 /* we loop through the pagelist before adding in order
105 to keep the pagelist sorted */
106 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
107 /* this check is to catch the case where a new
108 process could start writing to the same page
109 through a new pte. this new access can cause the
110 mkwrite even when the original ps's pte is marked
111 writable */
112 if (unlikely(cur == page))
113 goto page_already_added;
114 else if (cur->index > page->index)
115 break;
116 }
117
118 list_add_tail(&page->lru, &cur->lru);
119
120page_already_added:
121 mutex_unlock(&fbdefio->lock);
122
123 /* come back after delay to process the deferred IO */
124 schedule_delayed_work(&info->deferred_work, fbdefio->delay);
125 return 0;
126}
127
128static const struct vm_operations_struct fb_deferred_io_vm_ops = {
129 .fault = fb_deferred_io_fault,
130 .page_mkwrite = fb_deferred_io_mkwrite,
131};
132
133static int fb_deferred_io_set_page_dirty(struct page *page)
134{
135 if (!PageDirty(page))
136 SetPageDirty(page);
137 return 0;
138}
139
140static const struct address_space_operations fb_deferred_io_aops = {
141 .set_page_dirty = fb_deferred_io_set_page_dirty,
142};
143
144static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
145{
146 vma->vm_ops = &fb_deferred_io_vm_ops;
147 vma->vm_flags |= ( VM_RESERVED | VM_DONTEXPAND );
148 if (!(info->flags & FBINFO_VIRTFB))
149 vma->vm_flags |= VM_IO;
150 vma->vm_private_data = info;
151 return 0;
152}
153
154/* workqueue callback */
155static void fb_deferred_io_work(struct work_struct *work)
156{
157 struct fb_info *info = container_of(work, struct fb_info,
158 deferred_work.work);
159 struct list_head *node, *next;
160 struct page *cur;
161 struct fb_deferred_io *fbdefio = info->fbdefio;
162
163 /* here we mkclean the pages, then do all deferred IO */
164 mutex_lock(&fbdefio->lock);
165 list_for_each_entry(cur, &fbdefio->pagelist, lru) {
166 lock_page(cur);
167 page_mkclean(cur);
168 unlock_page(cur);
169 }
170
171 /* driver's callback with pagelist */
172 fbdefio->deferred_io(info, &fbdefio->pagelist);
173
174 /* clear the list */
175 list_for_each_safe(node, next, &fbdefio->pagelist) {
176 list_del(node);
177 }
178 mutex_unlock(&fbdefio->lock);
179}
180
181void fb_deferred_io_init(struct fb_info *info)
182{
183 struct fb_deferred_io *fbdefio = info->fbdefio;
184
185 BUG_ON(!fbdefio);
186 mutex_init(&fbdefio->lock);
187 info->fbops->fb_mmap = fb_deferred_io_mmap;
188 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
189 INIT_LIST_HEAD(&fbdefio->pagelist);
190 if (fbdefio->delay == 0) /* set a default of 1 s */
191 fbdefio->delay = HZ;
192}
193EXPORT_SYMBOL_GPL(fb_deferred_io_init);
194
195void fb_deferred_io_open(struct fb_info *info,
196 struct inode *inode,
197 struct file *file)
198{
199 file->f_mapping->a_ops = &fb_deferred_io_aops;
200}
201EXPORT_SYMBOL_GPL(fb_deferred_io_open);
202
203void fb_deferred_io_cleanup(struct fb_info *info)
204{
205 struct fb_deferred_io *fbdefio = info->fbdefio;
206 struct page *page;
207 int i;
208
209 BUG_ON(!fbdefio);
210 cancel_delayed_work(&info->deferred_work);
211 flush_scheduled_work();
212
213 /* clear out the mapping that we setup */
214 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
215 page = fb_deferred_io_page(info, i);
216 page->mapping = NULL;
217 }
218
219 info->fbops->fb_mmap = NULL;
220 mutex_destroy(&fbdefio->lock);
221}
222EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
223
224MODULE_LICENSE("GPL");