1 /*
2  * videobuf2-memops.c - generic memory handling routines for videobuf2
3  *
4  * Copyright (C) 2010 Samsung Electronics
5  *
6  * Author: Pawel Osciak <pawel@osciak.com>
7  *	   Marek Szyprowski <m.szyprowski@samsung.com>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation.
12  */
13 
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <linux/dma-mapping.h>
17 #include <linux/vmalloc.h>
18 #include <linux/mm.h>
19 #include <linux/sched.h>
20 #include <linux/file.h>
21 
22 #include <media/videobuf2-v4l2.h>
23 #include <media/videobuf2-memops.h>
24 
25 /**
26  * vb2_create_framevec() - map virtual addresses to pfns
27  * @start:	Virtual user address where we start mapping
28  * @length:	Length of a range to map
29  *
30  * This function allocates and fills in a vector with pfns corresponding to
31  * virtual address range passed in arguments. If pfns have corresponding pages,
32  * page references are also grabbed to pin pages in memory. The function
33  * returns pointer to the vector on success and error pointer in case of
34  * failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
35  */
36 struct frame_vector *vb2_create_framevec(unsigned long start,
37 					 unsigned long length)
38 {
39 	int ret;
40 	unsigned long first, last;
41 	unsigned long nr;
42 	struct frame_vector *vec;
43 	unsigned int flags = FOLL_FORCE | FOLL_WRITE;
44 
45 	first = start >> PAGE_SHIFT;
46 	last = (start + length - 1) >> PAGE_SHIFT;
47 	nr = last - first + 1;
48 	vec = frame_vector_create(nr);
49 	if (!vec)
50 		return ERR_PTR(-ENOMEM);
51 	ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
52 	if (ret < 0)
53 		goto out_destroy;
54 	/* We accept only complete set of PFNs */
55 	if (ret != nr) {
56 		ret = -EFAULT;
57 		goto out_release;
58 	}
59 	return vec;
60 out_release:
61 	put_vaddr_frames(vec);
62 out_destroy:
63 	frame_vector_destroy(vec);
64 	return ERR_PTR(ret);
65 }
66 EXPORT_SYMBOL(vb2_create_framevec);
67 
68 /**
69  * vb2_destroy_framevec() - release vector of mapped pfns
70  * @vec:	vector of pfns / pages to release
71  *
72  * This releases references to all pages in the vector @vec (if corresponding
73  * pfns are backed by pages) and frees the passed vector.
74  */
75 void vb2_destroy_framevec(struct frame_vector *vec)
76 {
77 	put_vaddr_frames(vec);
78 	frame_vector_destroy(vec);
79 }
80 EXPORT_SYMBOL(vb2_destroy_framevec);
81 
82 /**
83  * vb2_common_vm_open() - increase refcount of the vma
84  * @vma:	virtual memory region for the mapping
85  *
86  * This function adds another user to the provided vma. It expects
87  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
88  */
89 static void vb2_common_vm_open(struct vm_area_struct *vma)
90 {
91 	struct vb2_vmarea_handler *h = vma->vm_private_data;
92 
93 	pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
94 	       __func__, h, refcount_read(h->refcount), vma->vm_start,
95 	       vma->vm_end);
96 
97 	refcount_inc(h->refcount);
98 }
99 
100 /**
101  * vb2_common_vm_close() - decrease refcount of the vma
102  * @vma:	virtual memory region for the mapping
103  *
104  * This function releases the user from the provided vma. It expects
105  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
106  */
107 static void vb2_common_vm_close(struct vm_area_struct *vma)
108 {
109 	struct vb2_vmarea_handler *h = vma->vm_private_data;
110 
111 	pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
112 	       __func__, h, refcount_read(h->refcount), vma->vm_start,
113 	       vma->vm_end);
114 
115 	h->put(h->arg);
116 }
117 
118 /*
119  * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmapped
120  * video buffers
121  */
122 const struct vm_operations_struct vb2_common_vm_ops = {
123 	.open = vb2_common_vm_open,
124 	.close = vb2_common_vm_close,
125 };
126 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
127 
128 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
129 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
130 MODULE_LICENSE("GPL");
131