[media] v4l: videobuf2: add generic memory handling routines
Marek Szyprowski [Thu, 9 Dec 2010 13:20:47 +0000 (10:20 -0300)]
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>

drivers/media/video/Kconfig
drivers/media/video/Makefile
drivers/media/video/videobuf2-memops.c [new file with mode: 0644]
include/media/videobuf2-memops.h [new file with mode: 0644]

index a4a6aa7..aae5005 100644 (file)
@@ -47,6 +47,9 @@ config V4L2_MEM2MEM_DEV
 config VIDEOBUF2_CORE
        tristate
 
+config VIDEOBUF2_MEMOPS
+       tristate
+
 #
 # Multimedia Video device configuration
 #
index 6a1feba..fca0444 100644 (file)
@@ -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 (file)
index 0000000..053c157
--- /dev/null
@@ -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 (file)
index 0000000..fee1703
--- /dev/null
@@ -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