On Fri, Oct 28, 2011 at 10:50:29AM -0500, Kumar Gala wrote:
> 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.
Thanks for also providing an example driver showing the use of this.
You should also post this driver in a mainline-ready version, I'm a bit
uncomfortable with adding a new function pointer without having any users.
And since you change uio_driver.h you should also update documentation
accordingly (Documentation/DocBook/uio-howto.tmpl).
Otherwise, I have no general objections.
Thanks,
Hans
>
> 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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