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
  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  */
  36 struct 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  */
  66 void vb2_put_vma(struct vm_area_struct *vma)
  67 {
  68         if (!vma)
  69                 return;
  70
  71         if (vma->vm_file)
  72                 fput(vma->vm_file);
  73
  74         if (vma->vm_ops && vma->vm_ops->close)
  75                 vma->vm_ops->close(vma);
  76
  77         kfree(vma);
  78 }
  79 EXPORT_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  */
  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 EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
 145
 146 /**
 147  * vb2_mmap_pfn_range() - map physical pages to userspace
 148  * @vma:        virtual memory region for the mapping
 149  * @paddr:      starting physical address of the memory to be mapped
 150  * @size:       size of the memory to be mapped
 151  * @vm_ops:     vm operations to be assigned to the created area
 152  * @priv:       private data to be associated with the area
 153  *
 154  * Returns 0 on success.
 155  */
 156 int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
 157                                 unsigned long size,
 158                                 const struct vm_operations_struct *vm_ops,
 159                                 void *priv)
 160 {
 161         int ret;
 162
 163         size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
 164
 165         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 166         ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
 167                                 size, vma->vm_page_prot);
 168         if (ret) {
 169                 printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
 170                 return ret;
 171         }
 172
 173         vma->vm_flags           |= VM_DONTEXPAND | VM_RESERVED;
 174         vma->vm_private_data    = priv;
 175         vma->vm_ops             = vm_ops;
 176
 177         vma->vm_ops->open(vma);
 178
 179         pr_debug("%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
 180                         __func__, paddr, vma->vm_start, size);
 181
 182         return 0;
 183 }
 184 EXPORT_SYMBOL_GPL(vb2_mmap_pfn_range);
 185
 186 /**
 187  * vb2_common_vm_open() - increase refcount of the vma
 188  * @vma:        virtual memory region for the mapping
 189  *
 190  * This function adds another user to the provided vma. It expects
 191  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
 192  */
 193 static void vb2_common_vm_open(struct vm_area_struct *vma)
 194 {
 195         struct vb2_vmarea_handler *h = vma->vm_private_data;
 196
 197         pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
 198                __func__, h, atomic_read(h->refcount), vma->vm_start,
 199                vma->vm_end);
 200
 201         atomic_inc(h->refcount);
 202 }
 203
 204 /**
 205  * vb2_common_vm_close() - decrease refcount of the vma
 206  * @vma:        virtual memory region for the mapping
 207  *
 208  * This function releases the user from the provided vma. It expects
 209  * struct vb2_vmarea_handler pointer in vma->vm_private_data.
 210  */
 211 static void vb2_common_vm_close(struct vm_area_struct *vma)
 212 {
 213         struct vb2_vmarea_handler *h = vma->vm_private_data;
 214
 215         pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
 216                __func__, h, atomic_read(h->refcount), vma->vm_start,
 217                vma->vm_end);
 218
 219         h->put(h->arg);
 220 }
 221
 222 /**
 223  * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
 224  * video buffers
 225  */
 226 const struct vm_operations_struct vb2_common_vm_ops = {
 227         .open = vb2_common_vm_open,
 228         .close = vb2_common_vm_close,
 229 };
 230 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
 231
 232 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
 233 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 234 MODULE_LICENSE("GPL");