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  * @write:	Should we map for writing into the area
30  *
31  * This function allocates and fills in a vector with pfns corresponding to
32  * virtual address range passed in arguments. If pfns have corresponding pages,
33  * page references are also grabbed to pin pages in memory. The function
34  * returns pointer to the vector on success and error pointer in case of
35  * failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
36  */
vb2_create_framevec(unsigned long start,unsigned long length,bool write)37 struct frame_vector *vb2_create_framevec(unsigned long start,
38 					 unsigned long length,
39 					 bool write)
40 {
41 	int ret;
42 	unsigned long first, last;
43 	unsigned long nr;
44 	struct frame_vector *vec;
45 
46 	first = start >> PAGE_SHIFT;
47 	last = (start + length - 1) >> PAGE_SHIFT;
48 	nr = last - first + 1;
49 	vec = frame_vector_create(nr);
50 	if (!vec)
51 		return ERR_PTR(-ENOMEM);
52 	ret = get_vaddr_frames(start & PAGE_MASK, nr, write, vec);
53 	if (ret < 0)
54 		goto out_destroy;
55 	/* We accept only complete set of PFNs */
56 	if (ret != nr) {
57 		ret = -EFAULT;
58 		goto out_release;
59 	}
60 	return vec;
61 out_release:
62 	put_vaddr_frames(vec);
63 out_destroy:
64 	frame_vector_destroy(vec);
65 	return ERR_PTR(ret);
66 }
67 EXPORT_SYMBOL(vb2_create_framevec);
68 
69 /**
70  * vb2_destroy_framevec() - release vector of mapped pfns
71  * @vec:	vector of pfns / pages to release
72  *
73  * This releases references to all pages in the vector @vec (if corresponding
74  * pfns are backed by pages) and frees the passed vector.
75  */
vb2_destroy_framevec(struct frame_vector * vec)76 void vb2_destroy_framevec(struct frame_vector *vec)
77 {
78 	put_vaddr_frames(vec);
79 	frame_vector_destroy(vec);
80 }
81 EXPORT_SYMBOL(vb2_destroy_framevec);
82 
83 /**
84  * vb2_common_vm_open() - increase refcount of the vma
85  * @vma:	virtual memory region for the mapping
86  *
87  * This function adds another user to the provided vma. It expects
88  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
89  */
vb2_common_vm_open(struct vm_area_struct * vma)90 static void vb2_common_vm_open(struct vm_area_struct *vma)
91 {
92 	struct vb2_vmarea_handler *h = vma->vm_private_data;
93 
94 	pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
95 	       __func__, h, refcount_read(h->refcount), vma->vm_start,
96 	       vma->vm_end);
97 
98 	refcount_inc(h->refcount);
99 }
100 
101 /**
102  * vb2_common_vm_close() - decrease refcount of the vma
103  * @vma:	virtual memory region for the mapping
104  *
105  * This function releases the user from the provided vma. It expects
106  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
107  */
vb2_common_vm_close(struct vm_area_struct * vma)108 static void vb2_common_vm_close(struct vm_area_struct *vma)
109 {
110 	struct vb2_vmarea_handler *h = vma->vm_private_data;
111 
112 	pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
113 	       __func__, h, refcount_read(h->refcount), vma->vm_start,
114 	       vma->vm_end);
115 
116 	h->put(h->arg);
117 }
118 
119 /*
120  * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmapped
121  * video buffers
122  */
123 const struct vm_operations_struct vb2_common_vm_ops = {
124 	.open = vb2_common_vm_open,
125 	.close = vb2_common_vm_close,
126 };
127 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
128 
129 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
130 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
131 MODULE_LICENSE("GPL");
132