| /* |
| * videobuf2-memops.c - generic memory handling routines for videobuf2 |
| * |
| * Copyright (C) 2010 Samsung Electronics |
| * |
| * Author: Pawel Osciak <pawel@osciak.com> |
| * Marek Szyprowski <m.szyprowski@samsung.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation. |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <linux/dma-mapping.h> |
| #include <linux/vmalloc.h> |
| #include <linux/mm.h> |
| #include <linux/sched.h> |
| #include <linux/file.h> |
| |
| #include <media/videobuf2-core.h> |
| #include <media/videobuf2-memops.h> |
| |
| /** |
| * vb2_get_vma() - acquire and lock the virtual memory area |
| * @vma: given virtual memory area |
| * |
| * This function attempts to acquire an area mapped in the userspace for |
| * the duration of a hardware operation. The area is "locked" by performing |
| * the same set of operation that are done when process calls fork() and |
| * memory areas are duplicated. |
| * |
| * Returns a copy of a virtual memory region on success or NULL. |
| */ |
| struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma) |
| { |
| struct vm_area_struct *vma_copy; |
| |
| vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL); |
| if (vma_copy == NULL) |
| return NULL; |
| |
| if (vma->vm_ops && vma->vm_ops->open) |
| vma->vm_ops->open(vma); |
| |
| if (vma->vm_file) |
| get_file(vma->vm_file); |
| |
| memcpy(vma_copy, vma, sizeof(*vma)); |
| |
| vma_copy->vm_mm = NULL; |
| vma_copy->vm_next = NULL; |
| vma_copy->vm_prev = NULL; |
| |
| return vma_copy; |
| } |
| EXPORT_SYMBOL_GPL(vb2_get_vma); |
| |
| /** |
| * vb2_put_userptr() - release a userspace virtual memory area |
| * @vma: virtual memory region associated with the area to be released |
| * |
| * This function releases the previously acquired memory area after a hardware |
| * operation. |
| */ |
| void vb2_put_vma(struct vm_area_struct *vma) |
| { |
| if (!vma) |
| return; |
| |
| if (vma->vm_ops && vma->vm_ops->close) |
| vma->vm_ops->close(vma); |
| |
| if (vma->vm_file) |
| fput(vma->vm_file); |
| |
| kfree(vma); |
| } |
| EXPORT_SYMBOL_GPL(vb2_put_vma); |
| |
| /** |
| * vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory |
| * @vaddr: starting virtual address of the area to be verified |
| * @size: size of the area |
| * @res_paddr: will return physical address for the given vaddr |
| * @res_vma: will return locked copy of struct vm_area for the given area |
| * |
| * This function will go through memory area of size @size mapped at @vaddr and |
| * verify that the underlying physical pages are contiguous. If they are |
| * contiguous the virtual memory area is locked and a @res_vma is filled with |
| * the copy and @res_pa set to the physical address of the buffer. |
| * |
| * Returns 0 on success. |
| */ |
| int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size, |
| struct vm_area_struct **res_vma, dma_addr_t *res_pa) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| unsigned long offset, start, end; |
| unsigned long this_pfn, prev_pfn; |
| dma_addr_t pa = 0; |
| |
| start = vaddr; |
| offset = start & ~PAGE_MASK; |
| end = start + size; |
| |
| vma = find_vma(mm, start); |
| |
| if (vma == NULL || vma->vm_end < end) |
| return -EFAULT; |
| |
| for (prev_pfn = 0; start < end; start += PAGE_SIZE) { |
| int ret = follow_pfn(vma, start, &this_pfn); |
| if (ret) |
| return ret; |
| |
| if (prev_pfn == 0) |
| pa = this_pfn << PAGE_SHIFT; |
| else if (this_pfn != prev_pfn + 1) |
| return -EFAULT; |
| |
| prev_pfn = this_pfn; |
| } |
| |
| /* |
| * Memory is contigous, lock vma and return to the caller |
| */ |
| *res_vma = vb2_get_vma(vma); |
| if (*res_vma == NULL) |
| return -ENOMEM; |
| |
| *res_pa = pa + offset; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(vb2_get_contig_userptr); |
| |
| /** |
| * vb2_common_vm_open() - increase refcount of the vma |
| * @vma: virtual memory region for the mapping |
| * |
| * This function adds another user to the provided vma. It expects |
| * struct vb2_vmarea_handler pointer in vma->vm_private_data. |
| */ |
| static void vb2_common_vm_open(struct vm_area_struct *vma) |
| { |
| struct vb2_vmarea_handler *h = vma->vm_private_data; |
| |
| pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n", |
| __func__, h, atomic_read(h->refcount), vma->vm_start, |
| vma->vm_end); |
| |
| atomic_inc(h->refcount); |
| } |
| |
| /** |
| * vb2_common_vm_close() - decrease refcount of the vma |
| * @vma: virtual memory region for the mapping |
| * |
| * This function releases the user from the provided vma. It expects |
| * struct vb2_vmarea_handler pointer in vma->vm_private_data. |
| */ |
| static void vb2_common_vm_close(struct vm_area_struct *vma) |
| { |
| struct vb2_vmarea_handler *h = vma->vm_private_data; |
| |
| pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n", |
| __func__, h, atomic_read(h->refcount), vma->vm_start, |
| vma->vm_end); |
| |
| h->put(h->arg); |
| } |
| |
| /** |
| * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped |
| * video buffers |
| */ |
| const struct vm_operations_struct vb2_common_vm_ops = { |
| .open = vb2_common_vm_open, |
| .close = vb2_common_vm_close, |
| }; |
| EXPORT_SYMBOL_GPL(vb2_common_vm_ops); |
| |
| MODULE_DESCRIPTION("common memory handling routines for videobuf2"); |
| MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>"); |
| MODULE_LICENSE("GPL"); |