[PATCH] UIO: Allow a UIO driver to override the default pgprot when we mmap

Kumar Gala
2011-10-12T14:43:48Z

For some devices the default behavior of pgprot_noncached is not
the correct flags for the address space. Provide a means for the
kernel side UIO driver to override the flags without having to
implement its own full mmap callback.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
---
drivers/uio/uio.c | 6 +++++-
include/linux/uio_driver.h | 2 ++
2 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index d2efe82..88f4444 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -656,7 +656,11 @@ static int uio_mmap_physical(struct vm_area_struct *vma)

vma->vm_flags |= VM_IO | VM_RESERVED;

- vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ if (idev->info->mem[mi].set_pgprot)
+ vma->vm_page_prot =
+ idev->info->mem[mi].set_pgprot(vma->vm_page_prot);
+ else
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

return remap_pfn_range(vma,
vma->vm_start,
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 665517c..4c618cd 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -28,6 +28,7 @@ struct uio_map;
* @memtype: type of memory addr points to
* @internal_addr: ioremap-ped version of addr, for driver internal use
* @map: for use by the UIO core only.
+ * @set_pgprot: allow driver to override default(noncached) pgprot
*/
struct uio_mem {
const char *name;
@@ -36,6 +37,7 @@ struct uio_mem {
int memtype;
void __iomem *internal_addr;
struct uio_map *map;
+ pgprot_t (*set_pgprot)(pgprot_t prot);
};

#define MAX_UIO_MAPS 5
--
1.7.3.4