fbdev/amifb: Correct check for video memory size
[linux-2.6.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, int datasync)
70 {
71         struct fb_info *info = file->private_data;
72
73         /* Skip if deferred io is compiled-in but disabled on this fbdev */
74         if (!info->fbdefio)
75                 return 0;
76
77         /* Kill off the delayed work */
78         cancel_delayed_work_sync(&info->deferred_work);
79
80         /* Run it immediately */
81         return schedule_delayed_work(&info->deferred_work, 0);
82 }
83 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
84
85 /* vm_ops->page_mkwrite handler */
86 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
87                                   struct vm_fault *vmf)
88 {
89         struct page *page = vmf->page;
90         struct fb_info *info = vma->vm_private_data;
91         struct fb_deferred_io *fbdefio = info->fbdefio;
92         struct page *cur;
93
94         /* this is a callback we get when userspace first tries to
95         write to the page. we schedule a workqueue. that workqueue
96         will eventually mkclean the touched pages and execute the
97         deferred framebuffer IO. then if userspace touches a page
98         again, we repeat the same scheme */
99
100         /* protect against the workqueue changing the page list */
101         mutex_lock(&fbdefio->lock);
102
103         /*
104          * We want the page to remain locked from ->page_mkwrite until
105          * the PTE is marked dirty to avoid page_mkclean() being called
106          * before the PTE is updated, which would leave the page ignored
107          * by defio.
108          * Do this by locking the page here and informing the caller
109          * about it with VM_FAULT_LOCKED.
110          */
111         lock_page(page);
112
113         /* we loop through the pagelist before adding in order
114         to keep the pagelist sorted */
115         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
116                 /* this check is to catch the case where a new
117                 process could start writing to the same page
118                 through a new pte. this new access can cause the
119                 mkwrite even when the original ps's pte is marked
120                 writable */
121                 if (unlikely(cur == page))
122                         goto page_already_added;
123                 else if (cur->index > page->index)
124                         break;
125         }
126
127         list_add_tail(&page->lru, &cur->lru);
128
129 page_already_added:
130         mutex_unlock(&fbdefio->lock);
131
132         /* come back after delay to process the deferred IO */
133         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
134         return VM_FAULT_LOCKED;
135 }
136
137 static const struct vm_operations_struct fb_deferred_io_vm_ops = {
138         .fault          = fb_deferred_io_fault,
139         .page_mkwrite   = fb_deferred_io_mkwrite,
140 };
141
142 static int fb_deferred_io_set_page_dirty(struct page *page)
143 {
144         if (!PageDirty(page))
145                 SetPageDirty(page);
146         return 0;
147 }
148
149 static const struct address_space_operations fb_deferred_io_aops = {
150         .set_page_dirty = fb_deferred_io_set_page_dirty,
151 };
152
153 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
154 {
155         vma->vm_ops = &fb_deferred_io_vm_ops;
156         vma->vm_flags |= ( VM_RESERVED | VM_DONTEXPAND );
157         if (!(info->flags & FBINFO_VIRTFB))
158                 vma->vm_flags |= VM_IO;
159         vma->vm_private_data = info;
160         return 0;
161 }
162
163 /* workqueue callback */
164 static void fb_deferred_io_work(struct work_struct *work)
165 {
166         struct fb_info *info = container_of(work, struct fb_info,
167                                                 deferred_work.work);
168         struct list_head *node, *next;
169         struct page *cur;
170         struct fb_deferred_io *fbdefio = info->fbdefio;
171
172         /* here we mkclean the pages, then do all deferred IO */
173         mutex_lock(&fbdefio->lock);
174         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
175                 lock_page(cur);
176                 page_mkclean(cur);
177                 unlock_page(cur);
178         }
179
180         /* driver's callback with pagelist */
181         fbdefio->deferred_io(info, &fbdefio->pagelist);
182
183         /* clear the list */
184         list_for_each_safe(node, next, &fbdefio->pagelist) {
185                 list_del(node);
186         }
187         mutex_unlock(&fbdefio->lock);
188 }
189
190 void fb_deferred_io_init(struct fb_info *info)
191 {
192         struct fb_deferred_io *fbdefio = info->fbdefio;
193
194         BUG_ON(!fbdefio);
195         mutex_init(&fbdefio->lock);
196         info->fbops->fb_mmap = fb_deferred_io_mmap;
197         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
198         INIT_LIST_HEAD(&fbdefio->pagelist);
199         if (fbdefio->delay == 0) /* set a default of 1 s */
200                 fbdefio->delay = HZ;
201 }
202 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
203
204 void fb_deferred_io_open(struct fb_info *info,
205                          struct inode *inode,
206                          struct file *file)
207 {
208         file->f_mapping->a_ops = &fb_deferred_io_aops;
209 }
210 EXPORT_SYMBOL_GPL(fb_deferred_io_open);
211
212 void fb_deferred_io_cleanup(struct fb_info *info)
213 {
214         struct fb_deferred_io *fbdefio = info->fbdefio;
215         struct page *page;
216         int i;
217
218         BUG_ON(!fbdefio);
219         cancel_delayed_work(&info->deferred_work);
220         flush_scheduled_work();
221
222         /* clear out the mapping that we setup */
223         for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
224                 page = fb_deferred_io_page(info, i);
225                 page->mapping = NULL;
226         }
227
228         info->fbops->fb_mmap = NULL;
229         mutex_destroy(&fbdefio->lock);
230 }
231 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
232
233 MODULE_LICENSE("GPL");