For some devices, the default behavior of pgprot_noncached() is not
appropriate for all of its mappable regions. This provides a means for
the kernel side of the UIO driver to override the flags without having
to implement its own full mmap callback.
Signed-off-by: Kumar Gala <ga...@kernel.crashing.org>
Signed-off-by: Geoff Thorpe <ge...@geoffthorpe.net>
---
drivers/uio/uio.c | 6 +++++-
include/linux/uio_driver.h | 3 +++
2 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index dc27d89..0aebe27 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -655,7 +655,11 @@ 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->set_pgprot)
+ vma->vm_page_prot = idev->info->set_pgprot(idev->info, mi,
+ 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 fd99ff9..edfe7c8 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -80,6 +80,7 @@ struct uio_device;
* @open: open operation for this uio device
* @release: release operation for this uio device
* @irqcontrol: disable/enable irqs when 0/1 is written to
/dev/uioX
+ * @set_pgprot: allow driver to override default(noncached)
pgprot
*/
struct uio_info {
struct uio_device *uio_dev;
@@ -95,6 +96,8 @@ struct uio_info {
int (*open)(struct uio_info *info, struct inode *inode);
int (*release)(struct uio_info *info, struct inode *inode);
int (*irqcontrol)(struct uio_info *info, s32 irq_on);
+ pgprot_t (*set_pgprot)(struct uio_info *uio, unsigned int mem_idx,
+ pgprot_t prot);
};
extern int __must_check
--
1.7.3.4
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