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  */
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 	unsigned int flags = FOLL_FORCE;
46 
47 	if (write)
48 		flags |= FOLL_WRITE;
49 
50 	first = start >> PAGE_SHIFT;
51 	last = (start + length - 1) >> PAGE_SHIFT;
52 	nr = last - first + 1;
53 	vec = frame_vector_create(nr);
54 	if (!vec)
55 		return ERR_PTR(-ENOMEM);
56 	ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
57 	if (ret < 0)
58 		goto out_destroy;
59 	/* We accept only complete set of PFNs */
60 	if (ret != nr) {
61 		ret = -EFAULT;
62 		goto out_release;
63 	}
64 	return vec;
65 out_release:
66 	put_vaddr_frames(vec);
67 out_destroy:
68 	frame_vector_destroy(vec);
69 	return ERR_PTR(ret);
70 }
71 EXPORT_SYMBOL(vb2_create_framevec);
72 
73 /**
74  * vb2_destroy_framevec() - release vector of mapped pfns
75  * @vec:	vector of pfns / pages to release
76  *
77  * This releases references to all pages in the vector @vec (if corresponding
78  * pfns are backed by pages) and frees the passed vector.
79  */
80 void vb2_destroy_framevec(struct frame_vector *vec)
81 {
82 	put_vaddr_frames(vec);
83 	frame_vector_destroy(vec);
84 }
85 EXPORT_SYMBOL(vb2_destroy_framevec);
86 
87 /**
88  * vb2_common_vm_open() - increase refcount of the vma
89  * @vma:	virtual memory region for the mapping
90  *
91  * This function adds another user to the provided vma. It expects
92  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
93  */
94 static void vb2_common_vm_open(struct vm_area_struct *vma)
95 {
96 	struct vb2_vmarea_handler *h = vma->vm_private_data;
97 
98 	pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
99 	       __func__, h, refcount_read(h->refcount), vma->vm_start,
100 	       vma->vm_end);
101 
102 	refcount_inc(h->refcount);
103 }
104 
105 /**
106  * vb2_common_vm_close() - decrease refcount of the vma
107  * @vma:	virtual memory region for the mapping
108  *
109  * This function releases the user from the provided vma. It expects
110  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
111  */
112 static void vb2_common_vm_close(struct vm_area_struct *vma)
113 {
114 	struct vb2_vmarea_handler *h = vma->vm_private_data;
115 
116 	pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
117 	       __func__, h, refcount_read(h->refcount), vma->vm_start,
118 	       vma->vm_end);
119 
120 	h->put(h->arg);
121 }
122 
123 /*
124  * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmapped
125  * video buffers
126  */
127 const struct vm_operations_struct vb2_common_vm_ops = {
128 	.open = vb2_common_vm_open,
129 	.close = vb2_common_vm_close,
130 };
131 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
132 
133 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
134 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
135 MODULE_LICENSE("GPL");
136