| Submitter | Kumar Gala |
|---|---|
| Date | Oct. 12, 2011, 2:43 p.m. |
| Message ID | <1318430616-20351-1-git-send-email-galak@kernel.crashing.org> |
| Download | mbox | patch |
| Permalink | /patch/119224/ |
| State | Not Applicable |
| Delegated to: | Kumar Gala |
| Headers | show |
Comments
On Wed, Oct 12, 2011 at 09:43:36AM -0500, Kumar Gala wrote: > For some devices the default behavior of pgprot_noncached is not > the correct flags for the address space. For what devices? Can you give a real world usecase where this is needed? Thanks, Hans > 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 > >
On Oct 12, 2011, at 10:35 AM, Hans J. Koch wrote: > On Wed, Oct 12, 2011 at 09:43:36AM -0500, Kumar Gala wrote: >> For some devices the default behavior of pgprot_noncached is not >> the correct flags for the address space. > > For what devices? Can you give a real world usecase where this is needed? > > Thanks, > Hans In the Freescale Networking devices we have a coherent memory interface to our HW queuing system. In that case we want to change the pgprot() to be cache-able instead of non-cached. - k > >> 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 >> >>
On Wed, Oct 12, 2011 at 11:08:20AM -0500, Kumar Gala wrote: > > On Oct 12, 2011, at 10:35 AM, Hans J. Koch wrote: > > > On Wed, Oct 12, 2011 at 09:43:36AM -0500, Kumar Gala wrote: > >> For some devices the default behavior of pgprot_noncached is not > >> the correct flags for the address space. > > > > For what devices? Can you give a real world usecase where this is needed? > > > > Thanks, > > Hans > > In the Freescale Networking devices we have a coherent memory interface to our HW queuing system. In that case we want to change the pgprot() to be cache-able instead of non-cached. Could you please post the kernel part of that driver? Thanks, Hans
Patch
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
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(-)