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-core.h> 23#include <media/videobuf2-memops.h> 24 25/** 26 * vb2_get_vma() - acquire and lock the virtual memory area 27 * @vma: given virtual memory area 28 * 29 * This function attempts to acquire an area mapped in the userspace for 30 * the duration of a hardware operation. The area is "locked" by performing 31 * the same set of operation that are done when process calls fork() and 32 * memory areas are duplicated. 33 * 34 * Returns a copy of a virtual memory region on success or NULL. 35 */ 36struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma) 37{ 38 struct vm_area_struct *vma_copy; 39 40 vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL); 41 if (vma_copy == NULL) 42 return NULL; 43 44 if (vma->vm_ops && vma->vm_ops->open) 45 vma->vm_ops->open(vma); 46 47 if (vma->vm_file) 48 get_file(vma->vm_file); 49 50 memcpy(vma_copy, vma, sizeof(*vma)); 51 52 vma_copy->vm_mm = NULL; 53 vma_copy->vm_next = NULL; 54 vma_copy->vm_prev = NULL; 55 56 return vma_copy; 57} 58 59/** 60 * vb2_put_userptr() - release a userspace virtual memory area 61 * @vma: virtual memory region associated with the area to be released 62 * 63 * This function releases the previously acquired memory area after a hardware 64 * operation. 65 */ 66void vb2_put_vma(struct vm_area_struct *vma) 67{ 68 if (!vma) 69 return; 70 71 if (vma->vm_ops && vma->vm_ops->close) 72 vma->vm_ops->close(vma); 73 74 if (vma->vm_file) 75 fput(vma->vm_file); 76 77 kfree(vma); 78} 79EXPORT_SYMBOL_GPL(vb2_put_vma); 80 81/** 82 * vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory 83 * @vaddr: starting virtual address of the area to be verified 84 * @size: size of the area 85 * @res_paddr: will return physical address for the given vaddr 86 * @res_vma: will return locked copy of struct vm_area for the given area 87 * 88 * This function will go through memory area of size @size mapped at @vaddr and 89 * verify that the underlying physical pages are contiguous. If they are 90 * contiguous the virtual memory area is locked and a @res_vma is filled with 91 * the copy and @res_pa set to the physical address of the buffer. 92 * 93 * Returns 0 on success. 94 */ 95int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size, 96 struct vm_area_struct **res_vma, dma_addr_t *res_pa) 97{ 98 struct mm_struct *mm = current->mm; 99 struct vm_area_struct *vma; 100 unsigned long offset, start, end; 101 unsigned long this_pfn, prev_pfn; 102 dma_addr_t pa = 0; 103 104 start = vaddr; 105 offset = start & ~PAGE_MASK; 106 end = start + size; 107 108 vma = find_vma(mm, start); 109 110 if (vma == NULL || vma->vm_end < end) 111 return -EFAULT; 112 113 for (prev_pfn = 0; start < end; start += PAGE_SIZE) { 114 int ret = follow_pfn(vma, start, &this_pfn); 115 if (ret) 116 return ret; 117 118 if (prev_pfn == 0) 119 pa = this_pfn << PAGE_SHIFT; 120 else if (this_pfn != prev_pfn + 1) 121 return -EFAULT; 122 123 prev_pfn = this_pfn; 124 } 125 126 /* 127 * Memory is contigous, lock vma and return to the caller 128 */ 129 *res_vma = vb2_get_vma(vma); 130 if (*res_vma == NULL) 131 return -ENOMEM; 132 133 *res_pa = pa + offset; 134 return 0; 135} 136EXPORT_SYMBOL_GPL(vb2_get_contig_userptr); 137 138/** 139 * vb2_mmap_pfn_range() - map physical pages to userspace 140 * @vma: virtual memory region for the mapping 141 * @paddr: starting physical address of the memory to be mapped 142 * @size: size of the memory to be mapped 143 * @vm_ops: vm operations to be assigned to the created area 144 * @priv: private data to be associated with the area 145 * 146 * Returns 0 on success. 147 */ 148int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr, 149 unsigned long size, 150 const struct vm_operations_struct *vm_ops, 151 void *priv) 152{ 153 int ret; 154 155 size = min_t(unsigned long, vma->vm_end - vma->vm_start, size); 156 157 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 158 ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT, 159 size, vma->vm_page_prot); 160 if (ret) { 161 printk(KERN_ERR "Remapping memory failed, error: %d\n", ret); 162 return ret; 163 } 164 165 vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED; 166 vma->vm_private_data = priv; 167 vma->vm_ops = vm_ops; 168 169 vma->vm_ops->open(vma); 170 171 pr_debug("%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n", 172 __func__, paddr, vma->vm_start, size); 173 174 return 0; 175} 176EXPORT_SYMBOL_GPL(vb2_mmap_pfn_range); 177 178/** 179 * vb2_common_vm_open() - increase refcount of the vma 180 * @vma: virtual memory region for the mapping 181 * 182 * This function adds another user to the provided vma. It expects 183 * struct vb2_vmarea_handler pointer in vma->vm_private_data. 184 */ 185static void vb2_common_vm_open(struct vm_area_struct *vma) 186{ 187 struct vb2_vmarea_handler *h = vma->vm_private_data; 188 189 pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n", 190 __func__, h, atomic_read(h->refcount), vma->vm_start, 191 vma->vm_end); 192 193 atomic_inc(h->refcount); 194} 195 196/** 197 * vb2_common_vm_close() - decrease refcount of the vma 198 * @vma: virtual memory region for the mapping 199 * 200 * This function releases the user from the provided vma. It expects 201 * struct vb2_vmarea_handler pointer in vma->vm_private_data. 202 */ 203static void vb2_common_vm_close(struct vm_area_struct *vma) 204{ 205 struct vb2_vmarea_handler *h = vma->vm_private_data; 206 207 pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n", 208 __func__, h, atomic_read(h->refcount), vma->vm_start, 209 vma->vm_end); 210 211 h->put(h->arg); 212} 213 214/** 215 * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped 216 * video buffers 217 */ 218const struct vm_operations_struct vb2_common_vm_ops = { 219 .open = vb2_common_vm_open, 220 .close = vb2_common_vm_close, 221}; 222EXPORT_SYMBOL_GPL(vb2_common_vm_ops); 223 224MODULE_DESCRIPTION("common memory handling routines for videobuf2"); 225MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>"); 226MODULE_LICENSE("GPL"); 227