| Message ID | 1398353407-2345-2-git-send-email-santosh.shilimkar@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Apr 24, 2014 at 10:30 AM, Santosh Shilimkar <santosh.shilimkar@ti.com> wrote: > On few architectures, there are few restrictions on DMAble area of system > RAM. That also means that devices needs to know about this restrictions so > that the dma_masks can be updated accordingly and dma address translation > helpers can add/subtract the dma offset. > > In most of cases DMA addresses can be performed using offset value of > Bus address space relatively to physical address space as following: > > PFN->DMA: __pfn_to_phys(pfn + [-]dma_pfn_offset) > DMA->PFN: __phys_to_pfn(dma_addr) + [-]dma_pfn_offset > > So we introduce per device dma_pfn_offset which can be popullated > by architecture init code while creating the devices. > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Russell King <linux@arm.linux.org.uk> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Olof Johansson <olof@lixom.net> > Cc: Grant Likely <grant.likely@linaro.org> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Linus Walleij <linus.walleij@linaro.org> > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Rob Herring <robh@kernel.org> Rob > --- > include/linux/device.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/device.h b/include/linux/device.h > index 233bbbe..85a52d6 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -691,6 +691,7 @@ struct acpi_dev_node { > * @coherent_dma_mask: Like dma_mask, but for alloc_coherent mapping as not all > * hardware supports 64-bit addresses for consistent allocations > * such descriptors. > + * @dma_pfn_offset: offset of DMA memory range relatively of RAM > * @dma_parms: A low level driver may set these to teach IOMMU code about > * segment limitations. > * @dma_pools: Dma pools (if dma'ble device). > @@ -756,6 +757,7 @@ struct device { > not all hardware supports > 64 bit addresses for consistent > allocations such descriptors. */ > + unsigned long dma_pfn_offset; > > struct device_dma_parameters *dma_parms; > > -- > 1.7.9.5 >
diff --git a/include/linux/device.h b/include/linux/device.h index 233bbbe..85a52d6 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -691,6 +691,7 @@ struct acpi_dev_node { * @coherent_dma_mask: Like dma_mask, but for alloc_coherent mapping as not all * hardware supports 64-bit addresses for consistent allocations * such descriptors. + * @dma_pfn_offset: offset of DMA memory range relatively of RAM * @dma_parms: A low level driver may set these to teach IOMMU code about * segment limitations. * @dma_pools: Dma pools (if dma'ble device). @@ -756,6 +757,7 @@ struct device { not all hardware supports 64 bit addresses for consistent allocations such descriptors. */ + unsigned long dma_pfn_offset; struct device_dma_parameters *dma_parms;