Marek Szyprowski | 004cc37 | 2010-12-09 10:20:47 -0300 | [diff] [blame^] | 1 | /* |
| 2 | * videobuf2-memops.c - generic memory handling routines for videobuf2 |
| 3 | * |
| 4 | * Copyright (C) 2010 Samsung Electronics |
| 5 | * |
| 6 | * Author: Pawel Osciak <p.osciak@samsung.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 | #include <linux/slab.h> |
| 22 | |
| 23 | #include <media/videobuf2-core.h> |
| 24 | #include <media/videobuf2-memops.h> |
| 25 | |
| 26 | /** |
| 27 | * vb2_get_vma() - acquire and lock the virtual memory area |
| 28 | * @vma: given virtual memory area |
| 29 | * |
| 30 | * This function attempts to acquire an area mapped in the userspace for |
| 31 | * the duration of a hardware operation. The area is "locked" by performing |
| 32 | * the same set of operation that are done when process calls fork() and |
| 33 | * memory areas are duplicated. |
| 34 | * |
| 35 | * Returns a copy of a virtual memory region on success or NULL. |
| 36 | */ |
| 37 | struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma) |
| 38 | { |
| 39 | struct vm_area_struct *vma_copy; |
| 40 | |
| 41 | vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL); |
| 42 | if (vma_copy == NULL) |
| 43 | return NULL; |
| 44 | |
| 45 | if (vma->vm_ops && vma->vm_ops->open) |
| 46 | vma->vm_ops->open(vma); |
| 47 | |
| 48 | if (vma->vm_file) |
| 49 | get_file(vma->vm_file); |
| 50 | |
| 51 | memcpy(vma_copy, vma, sizeof(*vma)); |
| 52 | |
| 53 | vma_copy->vm_mm = NULL; |
| 54 | vma_copy->vm_next = NULL; |
| 55 | vma_copy->vm_prev = NULL; |
| 56 | |
| 57 | return vma_copy; |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * vb2_put_userptr() - release a userspace virtual memory area |
| 62 | * @vma: virtual memory region associated with the area to be released |
| 63 | * |
| 64 | * This function releases the previously acquired memory area after a hardware |
| 65 | * operation. |
| 66 | */ |
| 67 | void vb2_put_vma(struct vm_area_struct *vma) |
| 68 | { |
| 69 | if (!vma) |
| 70 | return; |
| 71 | |
| 72 | if (vma->vm_file) |
| 73 | fput(vma->vm_file); |
| 74 | |
| 75 | if (vma->vm_ops && vma->vm_ops->close) |
| 76 | vma->vm_ops->close(vma); |
| 77 | |
| 78 | kfree(vma); |
| 79 | } |
| 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 | */ |
| 95 | int 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 | int ret = -EFAULT; |
| 104 | |
| 105 | start = vaddr; |
| 106 | offset = start & ~PAGE_MASK; |
| 107 | end = start + size; |
| 108 | |
| 109 | down_read(&mm->mmap_sem); |
| 110 | vma = find_vma(mm, start); |
| 111 | |
| 112 | if (vma == NULL || vma->vm_end < end) |
| 113 | goto done; |
| 114 | |
| 115 | for (prev_pfn = 0; start < end; start += PAGE_SIZE) { |
| 116 | ret = follow_pfn(vma, start, &this_pfn); |
| 117 | if (ret) |
| 118 | goto done; |
| 119 | |
| 120 | if (prev_pfn == 0) |
| 121 | pa = this_pfn << PAGE_SHIFT; |
| 122 | else if (this_pfn != prev_pfn + 1) { |
| 123 | ret = -EFAULT; |
| 124 | goto done; |
| 125 | } |
| 126 | prev_pfn = this_pfn; |
| 127 | } |
| 128 | |
| 129 | /* |
| 130 | * Memory is contigous, lock vma and return to the caller |
| 131 | */ |
| 132 | *res_vma = vb2_get_vma(vma); |
| 133 | if (*res_vma == NULL) { |
| 134 | ret = -ENOMEM; |
| 135 | goto done; |
| 136 | } |
| 137 | *res_pa = pa + offset; |
| 138 | ret = 0; |
| 139 | |
| 140 | done: |
| 141 | up_read(&mm->mmap_sem); |
| 142 | return ret; |
| 143 | } |
| 144 | |
| 145 | /** |
| 146 | * vb2_mmap_pfn_range() - map physical pages to userspace |
| 147 | * @vma: virtual memory region for the mapping |
| 148 | * @paddr: starting physical address of the memory to be mapped |
| 149 | * @size: size of the memory to be mapped |
| 150 | * @vm_ops: vm operations to be assigned to the created area |
| 151 | * @priv: private data to be associated with the area |
| 152 | * |
| 153 | * Returns 0 on success. |
| 154 | */ |
| 155 | int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr, |
| 156 | unsigned long size, |
| 157 | const struct vm_operations_struct *vm_ops, |
| 158 | void *priv) |
| 159 | { |
| 160 | int ret; |
| 161 | |
| 162 | size = min_t(unsigned long, vma->vm_end - vma->vm_start, size); |
| 163 | |
| 164 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
| 165 | ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT, |
| 166 | size, vma->vm_page_prot); |
| 167 | if (ret) { |
| 168 | printk(KERN_ERR "Remapping memory failed, error: %d\n", ret); |
| 169 | return ret; |
| 170 | } |
| 171 | |
| 172 | vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED; |
| 173 | vma->vm_private_data = priv; |
| 174 | vma->vm_ops = vm_ops; |
| 175 | |
| 176 | vma->vm_ops->open(vma); |
| 177 | |
| 178 | printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n", |
| 179 | __func__, paddr, vma->vm_start, size); |
| 180 | |
| 181 | return 0; |
| 182 | } |
| 183 | |
| 184 | /** |
| 185 | * vb2_common_vm_open() - increase refcount of the vma |
| 186 | * @vma: virtual memory region for the mapping |
| 187 | * |
| 188 | * This function adds another user to the provided vma. It expects |
| 189 | * struct vb2_vmarea_handler pointer in vma->vm_private_data. |
| 190 | */ |
| 191 | static void vb2_common_vm_open(struct vm_area_struct *vma) |
| 192 | { |
| 193 | struct vb2_vmarea_handler *h = vma->vm_private_data; |
| 194 | |
| 195 | printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n", |
| 196 | __func__, h, atomic_read(h->refcount), vma->vm_start, |
| 197 | vma->vm_end); |
| 198 | |
| 199 | atomic_inc(h->refcount); |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * vb2_common_vm_close() - decrease refcount of the vma |
| 204 | * @vma: virtual memory region for the mapping |
| 205 | * |
| 206 | * This function releases the user from the provided vma. It expects |
| 207 | * struct vb2_vmarea_handler pointer in vma->vm_private_data. |
| 208 | */ |
| 209 | static void vb2_common_vm_close(struct vm_area_struct *vma) |
| 210 | { |
| 211 | struct vb2_vmarea_handler *h = vma->vm_private_data; |
| 212 | |
| 213 | printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n", |
| 214 | __func__, h, atomic_read(h->refcount), vma->vm_start, |
| 215 | vma->vm_end); |
| 216 | |
| 217 | h->put(h->arg); |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped |
| 222 | * video buffers |
| 223 | */ |
| 224 | const struct vm_operations_struct vb2_common_vm_ops = { |
| 225 | .open = vb2_common_vm_open, |
| 226 | .close = vb2_common_vm_close, |
| 227 | }; |
| 228 | EXPORT_SYMBOL_GPL(vb2_common_vm_ops); |
| 229 | |
| 230 | MODULE_DESCRIPTION("common memory handling routines for videobuf2"); |
| 231 | MODULE_AUTHOR("Pawel Osciak"); |
| 232 | MODULE_LICENSE("GPL"); |