From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- drivers/media/v4l2-core/videobuf2-memops.c | 187 +++++++++++++++++++++++++++++ 1 file changed, 187 insertions(+) create mode 100644 drivers/media/v4l2-core/videobuf2-memops.c (limited to 'drivers/media/v4l2-core/videobuf2-memops.c') diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c new file mode 100644 index 000000000..81c1ad8b2 --- /dev/null +++ b/drivers/media/v4l2-core/videobuf2-memops.c @@ -0,0 +1,187 @@ +/* + * videobuf2-memops.c - generic memory handling routines for videobuf2 + * + * Copyright (C) 2010 Samsung Electronics + * + * Author: Pawel Osciak + * Marek Szyprowski + * + * 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 +#include +#include +#include +#include +#include +#include + +#include +#include + +/** + * 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 "); +MODULE_LICENSE("GPL"); -- cgit v1.2.3-54-g00ecf