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
26static 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 */
40static 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
69int 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_inode(file);
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	schedule_delayed_work(&info->deferred_work, 0);
87	mutex_unlock(&inode->i_mutex);
88
89	return 0;
90}
91EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
92
93/* vm_ops->page_mkwrite handler */
94static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
95				  struct vm_fault *vmf)
96{
97	struct page *page = vmf->page;
98	struct fb_info *info = vma->vm_private_data;
99	struct fb_deferred_io *fbdefio = info->fbdefio;
100	struct page *cur;
101
102	/* this is a callback we get when userspace first tries to
103	write to the page. we schedule a workqueue. that workqueue
104	will eventually mkclean the touched pages and execute the
105	deferred framebuffer IO. then if userspace touches a page
106	again, we repeat the same scheme */
107
108	file_update_time(vma->vm_file);
109
110	/* protect against the workqueue changing the page list */
111	mutex_lock(&fbdefio->lock);
112
113	/* first write in this cycle, notify the driver */
114	if (fbdefio->first_io && list_empty(&fbdefio->pagelist))
115		fbdefio->first_io(info);
116
117	/*
118	 * We want the page to remain locked from ->page_mkwrite until
119	 * the PTE is marked dirty to avoid page_mkclean() being called
120	 * before the PTE is updated, which would leave the page ignored
121	 * by defio.
122	 * Do this by locking the page here and informing the caller
123	 * about it with VM_FAULT_LOCKED.
124	 */
125	lock_page(page);
126
127	/* we loop through the pagelist before adding in order
128	to keep the pagelist sorted */
129	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
130		/* this check is to catch the case where a new
131		process could start writing to the same page
132		through a new pte. this new access can cause the
133		mkwrite even when the original ps's pte is marked
134		writable */
135		if (unlikely(cur == page))
136			goto page_already_added;
137		else if (cur->index > page->index)
138			break;
139	}
140
141	list_add_tail(&page->lru, &cur->lru);
142
143page_already_added:
144	mutex_unlock(&fbdefio->lock);
145
146	/* come back after delay to process the deferred IO */
147	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
148	return VM_FAULT_LOCKED;
149}
150
151static const struct vm_operations_struct fb_deferred_io_vm_ops = {
152	.fault		= fb_deferred_io_fault,
153	.page_mkwrite	= fb_deferred_io_mkwrite,
154};
155
156static int fb_deferred_io_set_page_dirty(struct page *page)
157{
158	if (!PageDirty(page))
159		SetPageDirty(page);
160	return 0;
161}
162
163static const struct address_space_operations fb_deferred_io_aops = {
164	.set_page_dirty = fb_deferred_io_set_page_dirty,
165};
166
167static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
168{
169	vma->vm_ops = &fb_deferred_io_vm_ops;
170	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
171	if (!(info->flags & FBINFO_VIRTFB))
172		vma->vm_flags |= VM_IO;
173	vma->vm_private_data = info;
174	return 0;
175}
176
177/* workqueue callback */
178static void fb_deferred_io_work(struct work_struct *work)
179{
180	struct fb_info *info = container_of(work, struct fb_info,
181						deferred_work.work);
182	struct list_head *node, *next;
183	struct page *cur;
184	struct fb_deferred_io *fbdefio = info->fbdefio;
185
186	/* here we mkclean the pages, then do all deferred IO */
187	mutex_lock(&fbdefio->lock);
188	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
189		lock_page(cur);
190		page_mkclean(cur);
191		unlock_page(cur);
192	}
193
194	/* driver's callback with pagelist */
195	fbdefio->deferred_io(info, &fbdefio->pagelist);
196
197	/* clear the list */
198	list_for_each_safe(node, next, &fbdefio->pagelist) {
199		list_del(node);
200	}
201	mutex_unlock(&fbdefio->lock);
202}
203
204void fb_deferred_io_init(struct fb_info *info)
205{
206	struct fb_deferred_io *fbdefio = info->fbdefio;
207
208	BUG_ON(!fbdefio);
209	mutex_init(&fbdefio->lock);
210	info->fbops->fb_mmap = fb_deferred_io_mmap;
211	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
212	INIT_LIST_HEAD(&fbdefio->pagelist);
213	if (fbdefio->delay == 0) /* set a default of 1 s */
214		fbdefio->delay = HZ;
215}
216EXPORT_SYMBOL_GPL(fb_deferred_io_init);
217
218void fb_deferred_io_open(struct fb_info *info,
219			 struct inode *inode,
220			 struct file *file)
221{
222	file->f_mapping->a_ops = &fb_deferred_io_aops;
223}
224EXPORT_SYMBOL_GPL(fb_deferred_io_open);
225
226void fb_deferred_io_cleanup(struct fb_info *info)
227{
228	struct fb_deferred_io *fbdefio = info->fbdefio;
229	struct page *page;
230	int i;
231
232	BUG_ON(!fbdefio);
233	cancel_delayed_work_sync(&info->deferred_work);
234
235	/* clear out the mapping that we setup */
236	for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
237		page = fb_deferred_io_page(info, i);
238		page->mapping = NULL;
239	}
240
241	info->fbops->fb_mmap = NULL;
242	mutex_destroy(&fbdefio->lock);
243}
244EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
245
246MODULE_LICENSE("GPL");
247