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 */
 37struct 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;
 61out_release:
 62	put_vaddr_frames(vec);
 63out_destroy:
 64	frame_vector_destroy(vec);
 65	return ERR_PTR(ret);
 66}
 67EXPORT_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 */
 76void vb2_destroy_framevec(struct frame_vector *vec)
 77{
 78	put_vaddr_frames(vec);
 79	frame_vector_destroy(vec);
 80}
 81EXPORT_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 */
 90static 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 */
108static 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 */
123const struct vm_operations_struct vb2_common_vm_ops = {
124	.open = vb2_common_vm_open,
125	.close = vb2_common_vm_close,
126};
127EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
128
129MODULE_DESCRIPTION("common memory handling routines for videobuf2");
130MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
131MODULE_LICENSE("GPL");