[media] v4l: videobuf2: add generic memory handling routines

Add generic memory handling routines for userspace pointer handling,
contiguous memory verification and mapping.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

4 files changed, 281 insertions, 0 deletions

diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index a4a6aa703c26..aae5005cf86d 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -47,6 +47,9 @@ config V4L2_MEM2MEM_DEV
 config VIDEOBUF2_CORE
         tristate
 
+config VIDEOBUF2_MEMOPS
+        tristate
+
 #
 # Multimedia Video device configuration
 #
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 6a1feba87869..fca0444b66b1 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -112,6 +112,7 @@ obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
 obj-$(CONFIG_VIDEO_BTCX)  += btcx-risc.o
 
 obj-$(CONFIG_VIDEOBUF2_CORE)            += videobuf2-core.o
+obj-$(CONFIG_VIDEOBUF2_MEMOPS)          += videobuf2-memops.o
 
 obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
 
diff --git a/drivers/media/video/videobuf2-memops.c b/drivers/media/video/videobuf2-memops.c
new file mode 100644
index 000000000000..053c15794b8d
--- /dev/null
+++ b/drivers/media/video/videobuf2-memops.c
@@ -0,0 +1,232 @@
+/*
+ * videobuf2-memops.c - generic memory handling routines for videobuf2
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Pawel Osciak <p.osciak@samsung.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 <linux/slab.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;
+}
+
+/**
+ * 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_file)
+                fput(vma->vm_file);
+
+        if (vma->vm_ops && vma->vm_ops->close)
+                vma->vm_ops->close(vma);
+
+        kfree(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;
+        int ret = -EFAULT;
+
+        start = vaddr;
+        offset = start & ~PAGE_MASK;
+        end = start + size;
+
+        down_read(&mm->mmap_sem);
+        vma = find_vma(mm, start);
+
+        if (vma == NULL || vma->vm_end < end)
+                goto done;
+
+        for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
+                ret = follow_pfn(vma, start, &this_pfn);
+                if (ret)
+                        goto done;
+
+                if (prev_pfn == 0)
+                        pa = this_pfn << PAGE_SHIFT;
+                else if (this_pfn != prev_pfn + 1) {
+                        ret = -EFAULT;
+                        goto done;
+                }
+                prev_pfn = this_pfn;
+        }
+
+        /*
+         * Memory is contigous, lock vma and return to the caller
+         */
+        *res_vma = vb2_get_vma(vma);
+        if (*res_vma == NULL) {
+                ret = -ENOMEM;
+                goto done;
+        }
+        *res_pa = pa + offset;
+        ret = 0;
+
+done:
+        up_read(&mm->mmap_sem);
+        return ret;
+}
+
+/**
+ * vb2_mmap_pfn_range() - map physical pages to userspace
+ * @vma:        virtual memory region for the mapping
+ * @paddr:      starting physical address of the memory to be mapped
+ * @size:       size of the memory to be mapped
+ * @vm_ops:     vm operations to be assigned to the created area
+ * @priv:       private data to be associated with the area
+ *
+ * Returns 0 on success.
+ */
+int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
+                                unsigned long size,
+                                const struct vm_operations_struct *vm_ops,
+                                void *priv)
+{
+        int ret;
+
+        size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
+
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+        ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
+                                size, vma->vm_page_prot);
+        if (ret) {
+                printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
+                return ret;
+        }
+
+        vma->vm_flags           |= VM_DONTEXPAND | VM_RESERVED;
+        vma->vm_private_data    = priv;
+        vma->vm_ops             = vm_ops;
+
+        vma->vm_ops->open(vma);
+
+        printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
+                        __func__, paddr, vma->vm_start, size);
+
+        return 0;
+}
+
+/**
+ * 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;
+
+        printk(KERN_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;
+
+        printk(KERN_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");
diff --git a/include/media/videobuf2-memops.h b/include/media/videobuf2-memops.h
new file mode 100644
index 000000000000..fee17033a728
--- /dev/null
+++ b/include/media/videobuf2-memops.h
@@ -0,0 +1,45 @@
+/*
+ * videobuf2-memops.h - generic memory handling routines for videobuf2
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Pawel Osciak <p.osciak@samsung.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.
+ */
+
+#ifndef _MEDIA_VIDEOBUF2_MEMOPS_H
+#define _MEDIA_VIDEOBUF2_MEMOPS_H
+
+#include <media/videobuf2-core.h>
+
+/**
+ * vb2_vmarea_handler - common vma refcount tracking handler
+ * @refcount:   pointer to refcount entry in the buffer
+ * @put:        callback to function that decreases buffer refcount
+ * @arg:        argument for @put callback
+ */
+struct vb2_vmarea_handler {
+        atomic_t                *refcount;
+        void                    (*put)(void *arg);
+        void                    *arg;
+};
+
+extern const struct vm_operations_struct vb2_common_vm_ops;
+
+int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
+                           struct vm_area_struct **res_vma, dma_addr_t *res_pa);
+
+int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
+                                unsigned long size,
+                                const struct vm_operations_struct *vm_ops,
+                                void *priv);
+
+struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma);
+void vb2_put_vma(struct vm_area_struct *vma);
+
+
+#endif