[media] media: vb2: support userptr for PFN mappings

Some video devices need to use contiguous memory which is
not backed by pages as it happens with vmalloc. This patch
provides USERPTR handling for those devices.
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/videobuf2-vmalloc.c

@@ -10,6 +10,7 @@
  * the Free Software Foundation.
  */
 
+#include <linux/io.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
@@ -22,6 +23,7 @@
 struct vb2_vmalloc_buf {
 	void				*vaddr;
 	struct page			**pages;
+	struct vm_area_struct		*vma;
 	int				write;
 	unsigned long			size;
 	unsigned int			n_pages;
@@ -71,6 +73,8 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	struct vb2_vmalloc_buf *buf;
 	unsigned long first, last;
 	int n_pages, offset;
+	struct vm_area_struct *vma;
+	dma_addr_t physp;
 
 	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 	if (!buf)
@@ -80,23 +84,37 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	offset = vaddr & ~PAGE_MASK;
 	buf->size = size;
 
+
+	vma = find_vma(current->mm, vaddr);
+	if (vma && (vma->vm_flags & VM_PFNMAP) && (vma->vm_pgoff)) {
+		if (vb2_get_contig_userptr(vaddr, size, &vma, &physp))
+			goto fail_pages_array_alloc;
+		buf->vma = vma;
+		buf->vaddr = ioremap_nocache(physp, size);
+		if (!buf->vaddr)
+			goto fail_pages_array_alloc;
+	} else {
 		first = vaddr >> PAGE_SHIFT;
 		last  = (vaddr + size - 1) >> PAGE_SHIFT;
 		buf->n_pages = last - first + 1;
-	buf->pages = kzalloc(buf->n_pages * sizeof(struct page *), GFP_KERNEL);
+		buf->pages = kzalloc(buf->n_pages * sizeof(struct page *),
+				     GFP_KERNEL);
 		if (!buf->pages)
 			goto fail_pages_array_alloc;
 
 		/* current->mm->mmap_sem is taken by videobuf2 core */
-	n_pages = get_user_pages(current, current->mm, vaddr & PAGE_MASK,
-				 buf->n_pages, write, 1, /* force */
+		n_pages = get_user_pages(current, current->mm,
+					 vaddr & PAGE_MASK, buf->n_pages,
+					 write, 1, /* force */
 					 buf->pages, NULL);
 		if (n_pages != buf->n_pages)
 			goto fail_get_user_pages;
 
-	buf->vaddr = vm_map_ram(buf->pages, buf->n_pages, -1, PAGE_KERNEL);
+		buf->vaddr = vm_map_ram(buf->pages, buf->n_pages, -1,
+					PAGE_KERNEL);
 		if (!buf->vaddr)
 			goto fail_get_user_pages;
+	}
 
 	buf->vaddr += offset;
 	return buf;
@@ -120,6 +138,7 @@ static void vb2_vmalloc_put_userptr(void *buf_priv)
 	unsigned long vaddr = (unsigned long)buf->vaddr & PAGE_MASK;
 	unsigned int i;
 
+	if (buf->pages) {
 		if (vaddr)
 			vm_unmap_ram((void *)vaddr, buf->n_pages);
 		for (i = 0; i < buf->n_pages; ++i) {
@@ -128,6 +147,11 @@ static void vb2_vmalloc_put_userptr(void *buf_priv)
 			put_page(buf->pages[i]);
 		}
 		kfree(buf->pages);
+	} else {
+		if (buf->vma)
+			vb2_put_vma(buf->vma);
+		iounmap(buf->vaddr);
+	}
 	kfree(buf);
 }