2 * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
4 * Copyright (C) 2010 Samsung Electronics
6 * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation.
13 #include <linux/module.h>
15 #include <linux/scatterlist.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/vmalloc.h>
20 #include <media/videobuf2-core.h>
21 #include <media/videobuf2-memops.h>
22 #include <media/videobuf2-dma-sg.h>
25 module_param(debug, int, 0644);
27 #define dprintk(level, fmt, arg...) \
30 printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg); \
33 struct vb2_dma_sg_buf {
38 struct vb2_dma_sg_desc sg_desc;
40 struct vb2_vmarea_handler handler;
43 static void vb2_dma_sg_put(void *buf_priv);
45 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
47 struct vb2_dma_sg_buf *buf;
50 buf = kzalloc(sizeof *buf, GFP_KERNEL);
57 buf->sg_desc.size = size;
58 buf->sg_desc.num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
60 buf->sg_desc.sglist = vzalloc(buf->sg_desc.num_pages *
61 sizeof(*buf->sg_desc.sglist));
62 if (!buf->sg_desc.sglist)
63 goto fail_sglist_alloc;
64 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
66 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
69 goto fail_pages_array_alloc;
71 for (i = 0; i < buf->sg_desc.num_pages; ++i) {
72 buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO |
73 __GFP_NOWARN | gfp_flags);
74 if (NULL == buf->pages[i])
75 goto fail_pages_alloc;
76 sg_set_page(&buf->sg_desc.sglist[i],
77 buf->pages[i], PAGE_SIZE, 0);
80 buf->handler.refcount = &buf->refcount;
81 buf->handler.put = vb2_dma_sg_put;
82 buf->handler.arg = buf;
84 atomic_inc(&buf->refcount);
86 dprintk(1, "%s: Allocated buffer of %d pages\n",
87 __func__, buf->sg_desc.num_pages);
92 __free_page(buf->pages[i]);
95 fail_pages_array_alloc:
96 vfree(buf->sg_desc.sglist);
103 static void vb2_dma_sg_put(void *buf_priv)
105 struct vb2_dma_sg_buf *buf = buf_priv;
106 int i = buf->sg_desc.num_pages;
108 if (atomic_dec_and_test(&buf->refcount)) {
109 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
110 buf->sg_desc.num_pages);
112 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
113 vfree(buf->sg_desc.sglist);
115 __free_page(buf->pages[i]);
121 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
122 unsigned long size, int write)
124 struct vb2_dma_sg_buf *buf;
125 unsigned long first, last;
126 int num_pages_from_user, i;
128 buf = kzalloc(sizeof *buf, GFP_KERNEL);
134 buf->offset = vaddr & ~PAGE_MASK;
135 buf->sg_desc.size = size;
137 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
138 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
139 buf->sg_desc.num_pages = last - first + 1;
141 buf->sg_desc.sglist = vzalloc(
142 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
143 if (!buf->sg_desc.sglist)
144 goto userptr_fail_sglist_alloc;
146 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
148 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
151 goto userptr_fail_pages_array_alloc;
153 num_pages_from_user = get_user_pages(current, current->mm,
155 buf->sg_desc.num_pages,
161 if (num_pages_from_user != buf->sg_desc.num_pages)
162 goto userptr_fail_get_user_pages;
164 sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
165 PAGE_SIZE - buf->offset, buf->offset);
166 size -= PAGE_SIZE - buf->offset;
167 for (i = 1; i < buf->sg_desc.num_pages; ++i) {
168 sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
169 min_t(size_t, PAGE_SIZE, size), 0);
170 size -= min_t(size_t, PAGE_SIZE, size);
174 userptr_fail_get_user_pages:
175 dprintk(1, "get_user_pages requested/got: %d/%d]\n",
176 num_pages_from_user, buf->sg_desc.num_pages);
177 while (--num_pages_from_user >= 0)
178 put_page(buf->pages[num_pages_from_user]);
181 userptr_fail_pages_array_alloc:
182 vfree(buf->sg_desc.sglist);
184 userptr_fail_sglist_alloc:
190 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
193 static void vb2_dma_sg_put_userptr(void *buf_priv)
195 struct vb2_dma_sg_buf *buf = buf_priv;
196 int i = buf->sg_desc.num_pages;
198 dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
199 __func__, buf->sg_desc.num_pages);
201 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
204 set_page_dirty_lock(buf->pages[i]);
205 put_page(buf->pages[i]);
207 vfree(buf->sg_desc.sglist);
212 static void *vb2_dma_sg_vaddr(void *buf_priv)
214 struct vb2_dma_sg_buf *buf = buf_priv;
219 buf->vaddr = vm_map_ram(buf->pages,
220 buf->sg_desc.num_pages,
224 /* add offset in case userptr is not page-aligned */
225 return buf->vaddr + buf->offset;
228 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
230 struct vb2_dma_sg_buf *buf = buf_priv;
232 return atomic_read(&buf->refcount);
235 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
237 struct vb2_dma_sg_buf *buf = buf_priv;
238 unsigned long uaddr = vma->vm_start;
239 unsigned long usize = vma->vm_end - vma->vm_start;
243 printk(KERN_ERR "No memory to map\n");
250 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
252 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
262 * Use common vm_area operations to track buffer refcount.
264 vma->vm_private_data = &buf->handler;
265 vma->vm_ops = &vb2_common_vm_ops;
267 vma->vm_ops->open(vma);
272 static void *vb2_dma_sg_cookie(void *buf_priv)
274 struct vb2_dma_sg_buf *buf = buf_priv;
276 return &buf->sg_desc;
279 const struct vb2_mem_ops vb2_dma_sg_memops = {
280 .alloc = vb2_dma_sg_alloc,
281 .put = vb2_dma_sg_put,
282 .get_userptr = vb2_dma_sg_get_userptr,
283 .put_userptr = vb2_dma_sg_put_userptr,
284 .vaddr = vb2_dma_sg_vaddr,
285 .mmap = vb2_dma_sg_mmap,
286 .num_users = vb2_dma_sg_num_users,
287 .cookie = vb2_dma_sg_cookie,
289 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
291 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
292 MODULE_AUTHOR("Andrzej Pietrasiewicz");
293 MODULE_LICENSE("GPL");