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 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 */ 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 */ 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 */ 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