backports: add vm_iomap_memory()

This adds vm_iomap_memory() from:
commit b4cbb197c7e7a68dbad0d491242e3ca67420c13e
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue Apr 16 13:45:37 2013 -0700

    vm: add vm_iomap_memory() helper function

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>

diff --git a/backport/backport-include/linux/mm.h b/backport/backport-include/linux/mm.h
index 9ba1f00fbe7c7acf2eeb48a28e8da2754013076a..8671d299920484a466505f61c2303a42285db138 100644 (file)
--- a/backport/backport-include/linux/mm.h
+++ b/backport/backport-include/linux/mm.h
@@ -20,4 +20,9 @@
 #define VM_DONTDUMP    VM_NODUMP
 #endif
 
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,8,0))
+#define vm_iomap_memory LINUX_BACKPORT(vm_iomap_memory)
+int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
+#endif
+
 #endif /* __BACKPORT_MM_H */

diff --git a/backport/compat/compat-3.8.c b/backport/compat/compat-3.8.c
index 9f5df7d4a5fde3c5951e594efea0e0883cd14944..5b1ead9501c32e22a706bb2f18ae3890f781c967 100644 (file)
--- a/backport/compat/compat-3.8.c
+++ b/backport/compat/compat-3.8.c
@@ -363,3 +363,58 @@ bool hid_ignore(struct hid_device *hdev)
        return !!hid_match_id(hdev, hid_ignore_list);
 }
 EXPORT_SYMBOL_GPL(hid_ignore);
+
+/**
+ * Backport this:
+ * commit b4cbb197c7e7a68dbad0d491242e3ca67420c13e
+ * Author: Linus Torvalds <torvalds@linux-foundation.org>
+ * Date:   Tue Apr 16 13:45:37 2013 -0700
+ *
+ *     vm: add vm_iomap_memory() helper function
+ */
+/**
+ * vm_iomap_memory - remap memory to userspace
+ * @vma: user vma to map to
+ * @start: start of area
+ * @len: size of area
+ *
+ * This is a simplified io_remap_pfn_range() for common driver use. The
+ * driver just needs to give us the physical memory range to be mapped,
+ * we'll figure out the rest from the vma information.
+ *
+ * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
+ * whatever write-combining details or similar.
+ */
+int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
+{
+       unsigned long vm_len, pfn, pages;
+
+       /* Check that the physical memory area passed in looks valid */
+       if (start + len < start)
+               return -EINVAL;
+       /*
+        * You *really* shouldn't map things that aren't page-aligned,
+        * but we've historically allowed it because IO memory might
+        * just have smaller alignment.
+        */
+       len += start & ~PAGE_MASK;
+       pfn = start >> PAGE_SHIFT;
+       pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
+       if (pfn + pages < pfn)
+               return -EINVAL;
+
+       /* We start the mapping 'vm_pgoff' pages into the area */
+       if (vma->vm_pgoff > pages)
+               return -EINVAL;
+       pfn += vma->vm_pgoff;
+       pages -= vma->vm_pgoff;
+
+       /* Can we fit all of the mapping? */
+       vm_len = vma->vm_end - vma->vm_start;
+       if (vm_len >> PAGE_SHIFT > pages)
+               return -EINVAL;
+
+       /* Ok, let it rip */
+       return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_iomap_memory);