drivers/media/video/videobuf2-memops.c

   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 #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 EXPORT_SYMBOL_GPL(vb2_put_vma);
  81
  82 /**
  83  * vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory
  84  * @vaddr:      starting virtual address of the area to be verified
  85  * @size:       size of the area
  86  * @res_paddr:  will return physical address for the given vaddr
  87  * @res_vma:    will return locked copy of struct vm_area for the given area
  88  *
  89  * This function will go through memory area of size @size mapped at @vaddr and
  90  * verify that the underlying physical pages are contiguous. If they are
  91  * contiguous the virtual memory area is locked and a @res_vma is filled with
  92  * the copy and @res_pa set to the physical address of the buffer.
  93  *
  94  * Returns 0 on success.
  95  */
  96 int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
  97                            struct vm_area_struct **res_vma, dma_addr_t *res_pa)
  98 {
  99         struct mm_struct *mm = current->mm;
 100         struct vm_area_struct *vma;
 101         unsigned long offset, start, end;
 102         unsigned long this_pfn, prev_pfn;
 103         dma_addr_t pa = 0;
 104         int ret = -EFAULT;
 105
 106         start = vaddr;
 107         offset = start & ~PAGE_MASK;
 108         end = start + size;
 109
 110         down_read(&mm->mmap_sem);
 111         vma = find_vma(mm, start);
 112
 113         if (vma == NULL || vma->vm_end < end)
 114                 goto done;
 115
 116         for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
 117                 ret = follow_pfn(vma, start, &this_pfn);
 118                 if (ret)
 119                         goto done;
 120
 121                 if (prev_pfn == 0)
 122                         pa = this_pfn << PAGE_SHIFT;
 123                 else if (this_pfn != prev_pfn + 1) {
 124                         ret = -EFAULT;
 125                         goto done;
 126                 }
 127                 prev_pfn = this_pfn;
 128         }
 129
 130         /*
 131          * Memory is contigous, lock vma and return to the caller
 132          */
 133         *res_vma = vb2_get_vma(vma);
 134         if (*res_vma == NULL) {
 135                 ret = -ENOMEM;
 136                 goto done;
 137         }
 138         *res_pa = pa + offset;
 139         ret = 0;
 140
 141 done:
 142         up_read(&mm->mmap_sem);
 143         return ret;
 144 }
 145 EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
 146
 147 /**
 148  * vb2_mmap_pfn_range() - map physical pages to userspace
 149  * @vma:        virtual memory region for the mapping
 150  * @paddr:      starting physical address of the memory to be mapped
 151  * @size:       size of the memory to be mapped
 152  * @vm_ops:     vm operations to be assigned to the created area
 153  * @priv:       private data to be associated with the area
 154  *
 155  * Returns 0 on success.
 156  */
 157 int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
 158                                 unsigned long size,
 159                                 const struct vm_operations_struct *vm_ops,
 160                                 void *priv)
 161 {
 162         int ret;
 163
 164         size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
 165
 166         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 167         ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
 168                                 size, vma->vm_page_prot);
 169         if (ret) {
 170                 printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
 171                 return ret;
 172         }
 173
 174         vma->vm_flags           |= VM_DONTEXPAND | VM_RESERVED;
 175         vma->vm_private_data    = priv;
 176         vma->vm_ops             = vm_ops;
 177
 178         vma->vm_ops->open(vma);
 179
 180         printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
 181                         __func__, paddr, vma->vm_start, size);
 182
 183         return 0;
 184 }
 185 EXPORT_SYMBOL_GPL(vb2_mmap_pfn_range);
 186
 187 /**
 188  * vb2_common_vm_open() - increase refcount of the vma
 189  * @vma:        virtual memory region for the mapping
 190  *
 191  * This function adds another user to the provided vma. It expects
 192  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
 193  */
 194 static void vb2_common_vm_open(struct vm_area_struct *vma)
 195 {
 196         struct vb2_vmarea_handler *h = vma->vm_private_data;
 197
 198         printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n",
 199                __func__, h, atomic_read(h->refcount), vma->vm_start,
 200                vma->vm_end);
 201
 202         atomic_inc(h->refcount);
 203 }
 204
 205 /**
 206  * vb2_common_vm_close() - decrease refcount of the vma
 207  * @vma:        virtual memory region for the mapping
 208  *
 209  * This function releases the user from the provided vma. It expects
 210  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
 211  */
 212 static void vb2_common_vm_close(struct vm_area_struct *vma)
 213 {
 214         struct vb2_vmarea_handler *h = vma->vm_private_data;
 215
 216         printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n",
 217                __func__, h, atomic_read(h->refcount), vma->vm_start,
 218                vma->vm_end);
 219
 220         h->put(h->arg);
 221 }
 222
 223 /**
 224  * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
 225  * video buffers
 226  */
 227 const struct vm_operations_struct vb2_common_vm_ops = {
 228         .open = vb2_common_vm_open,
 229         .close = vb2_common_vm_close,
 230 };
 231 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
 232
 233 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
 234 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 235 MODULE_LICENSE("GPL");