Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux
[pandora-kernel.git] / drivers / video / fb_defio.c
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/vmalloc.h>
17 #include <linux/delay.h>
18 #include <linux/interrupt.h>
19 #include <linux/fb.h>
20 #include <linux/list.h>
21
22 /* to support deferred IO */
23 #include <linux/rmap.h>
24 #include <linux/pagemap.h>
25
26 struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs)
27 {
28         void *screen_base = (void __force *) info->screen_base;
29         struct page *page;
30
31         if (is_vmalloc_addr(screen_base + offs))
32                 page = vmalloc_to_page(screen_base + offs);
33         else
34                 page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT);
35
36         return page;
37 }
38
39 /* this is to find and return the vmalloc-ed fb pages */
40 static int fb_deferred_io_fault(struct vm_area_struct *vma,
41                                 struct vm_fault *vmf)
42 {
43         unsigned long offset;
44         struct page *page;
45         struct fb_info *info = vma->vm_private_data;
46
47         offset = vmf->pgoff << PAGE_SHIFT;
48         if (offset >= info->fix.smem_len)
49                 return VM_FAULT_SIGBUS;
50
51         page = fb_deferred_io_page(info, offset);
52         if (!page)
53                 return VM_FAULT_SIGBUS;
54
55         get_page(page);
56
57         if (vma->vm_file)
58                 page->mapping = vma->vm_file->f_mapping;
59         else
60                 printk(KERN_ERR "no mapping available\n");
61
62         BUG_ON(!page->mapping);
63         page->index = vmf->pgoff;
64
65         vmf->page = page;
66         return 0;
67 }
68
69 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync)
70 {
71         struct fb_info *info = file->private_data;
72         struct inode *inode = file->f_path.dentry->d_inode;
73         int err = filemap_write_and_wait_range(inode->i_mapping, start, end);
74         if (err)
75                 return err;
76
77         /* Skip if deferred io is compiled-in but disabled on this fbdev */
78         if (!info->fbdefio)
79                 return 0;
80
81         mutex_lock(&inode->i_mutex);
82         /* Kill off the delayed work */
83         cancel_delayed_work_sync(&info->deferred_work);
84
85         /* Run it immediately */
86         err = schedule_delayed_work(&info->deferred_work, 0);
87         mutex_unlock(&inode->i_mutex);
88         return err;
89 }
90 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
91
92 /* vm_ops->page_mkwrite handler */
93 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
94                                   struct vm_fault *vmf)
95 {
96         struct page *page = vmf->page;
97         struct fb_info *info = vma->vm_private_data;
98         struct fb_deferred_io *fbdefio = info->fbdefio;
99         struct page *cur;
100
101         /* this is a callback we get when userspace first tries to
102         write to the page. we schedule a workqueue. that workqueue
103         will eventually mkclean the touched pages and execute the
104         deferred framebuffer IO. then if userspace touches a page
105         again, we repeat the same scheme */
106
107         /* protect against the workqueue changing the page list */
108         mutex_lock(&fbdefio->lock);
109
110         /*
111          * We want the page to remain locked from ->page_mkwrite until
112          * the PTE is marked dirty to avoid page_mkclean() being called
113          * before the PTE is updated, which would leave the page ignored
114          * by defio.
115          * Do this by locking the page here and informing the caller
116          * about it with VM_FAULT_LOCKED.
117          */
118         lock_page(page);
119
120         /* we loop through the pagelist before adding in order
121         to keep the pagelist sorted */
122         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
123                 /* this check is to catch the case where a new
124                 process could start writing to the same page
125                 through a new pte. this new access can cause the
126                 mkwrite even when the original ps's pte is marked
127                 writable */
128                 if (unlikely(cur == page))
129                         goto page_already_added;
130                 else if (cur->index > page->index)
131                         break;
132         }
133
134         list_add_tail(&page->lru, &cur->lru);
135
136 page_already_added:
137         mutex_unlock(&fbdefio->lock);
138
139         /* come back after delay to process the deferred IO */
140         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
141         return VM_FAULT_LOCKED;
142 }
143
144 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
145         .fault          = fb_deferred_io_fault,
146         .page_mkwrite   = fb_deferred_io_mkwrite,
147 };
148
149 static int fb_deferred_io_set_page_dirty(struct page *page)
150 {
151         if (!PageDirty(page))
152                 SetPageDirty(page);
153         return 0;
154 }
155
156 static const struct address_space_operations fb_deferred_io_aops = {
157         .set_page_dirty = fb_deferred_io_set_page_dirty,
158 };
159
160 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
161 {
162         vma->vm_ops = &fb_deferred_io_vm_ops;
163         vma->vm_flags |= ( VM_RESERVED | VM_DONTEXPAND );
164         if (!(info->flags & FBINFO_VIRTFB))
165                 vma->vm_flags |= VM_IO;
166         vma->vm_private_data = info;
167         return 0;
168 }
169
170 /* workqueue callback */
171 static void fb_deferred_io_work(struct work_struct *work)
172 {
173         struct fb_info *info = container_of(work, struct fb_info,
174                                                 deferred_work.work);
175         struct list_head *node, *next;
176         struct page *cur;
177         struct fb_deferred_io *fbdefio = info->fbdefio;
178
179         /* here we mkclean the pages, then do all deferred IO */
180         mutex_lock(&fbdefio->lock);
181         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
182                 lock_page(cur);
183                 page_mkclean(cur);
184                 unlock_page(cur);
185         }
186
187         /* driver's callback with pagelist */
188         fbdefio->deferred_io(info, &fbdefio->pagelist);
189
190         /* clear the list */
191         list_for_each_safe(node, next, &fbdefio->pagelist) {
192                 list_del(node);
193         }
194         mutex_unlock(&fbdefio->lock);
195 }
196
197 void fb_deferred_io_init(struct fb_info *info)
198 {
199         struct fb_deferred_io *fbdefio = info->fbdefio;
200
201         BUG_ON(!fbdefio);
202         mutex_init(&fbdefio->lock);
203         info->fbops->fb_mmap = fb_deferred_io_mmap;
204         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
205         INIT_LIST_HEAD(&fbdefio->pagelist);
206         if (fbdefio->delay == 0) /* set a default of 1 s */
207                 fbdefio->delay = HZ;
208 }
209 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
210
211 void fb_deferred_io_open(struct fb_info *info,
212                          struct inode *inode,
213                          struct file *file)
214 {
215         file->f_mapping->a_ops = &fb_deferred_io_aops;
216 }
217 EXPORT_SYMBOL_GPL(fb_deferred_io_open);
218
219 void fb_deferred_io_cleanup(struct fb_info *info)
220 {
221         struct fb_deferred_io *fbdefio = info->fbdefio;
222         struct page *page;
223         int i;
224
225         BUG_ON(!fbdefio);
226         cancel_delayed_work(&info->deferred_work);
227         flush_scheduled_work();
228
229         /* clear out the mapping that we setup */
230         for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
231                 page = fb_deferred_io_page(info, i);
232                 page->mapping = NULL;
233         }
234
235         info->fbops->fb_mmap = NULL;
236         mutex_destroy(&fbdefio->lock);
237 }
238 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
239
240 MODULE_LICENSE("GPL");