--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff