| Message ID | 1401981720-6946-1-git-send-email-santosh.shilimkar@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 05, 2014 at 11:22:00AM -0400, Santosh Shilimkar wrote: > Recently we introduced the generic device tree infrastructure for couple of DMA > bus parameter, dma-ranges and dma-coherent. Update the documentation so that > its useful for future users. > > The "dma-ranges" property is intended to be used for describing the > configuration of DMA bus RAM addresses and its offset w.r.t CPU addresses. > > The "dma-coherent" property is intended to be used for identifying devices > supported coherent DMA operations. > > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Grant Likely <grant.likely@linaro.org> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Pawel Moll <pawel.moll@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Ian Campbell <ijc+devicetree@hellion.org.uk> > Cc: Shawn Guo <shawn.guo@freescale.com> > Cc: Kumar Gala <galak@codeaurora.org> > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Thanks for the documentation. I think it's definitely useful for future users of the binding. Acked-by: Shawn Guo <shawn.guo@freescale.com>
On Thu, Jun 5, 2014 at 12:22 PM, Santosh Shilimkar <santosh.shilimkar@ti.com> wrote: > Recently we introduced the generic device tree infrastructure for couple of DMA > bus parameter, dma-ranges and dma-coherent. Update the documentation so that > its useful for future users. > > The "dma-ranges" property is intended to be used for describing the > configuration of DMA bus RAM addresses and its offset w.r.t CPU addresses. > > The "dma-coherent" property is intended to be used for identifying devices > supported coherent DMA operations. > > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Grant Likely <grant.likely@linaro.org> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Pawel Moll <pawel.moll@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Ian Campbell <ijc+devicetree@hellion.org.uk> > Cc: Shawn Guo <shawn.guo@freescale.com> > Cc: Kumar Gala <galak@codeaurora.org> > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> > --- > Documentation/devicetree/booting-without-of.txt | 60 +++++++++++++++++++++++ > 1 file changed, 60 insertions(+) > > diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt > index 1f013bd..f0120c1 100644 > --- a/Documentation/devicetree/booting-without-of.txt > +++ b/Documentation/devicetree/booting-without-of.txt > @@ -51,6 +51,8 @@ Table of Contents > > VIII - Specifying device power management information (sleep property) > > + VIV - Specifying dma bus information "9" in Roman numeral is "IX"
On Sunday 08 June 2014 10:13 PM, Fabio Estevam wrote: > On Thu, Jun 5, 2014 at 12:22 PM, Santosh Shilimkar > <santosh.shilimkar@ti.com> wrote: >> Recently we introduced the generic device tree infrastructure for couple of DMA >> bus parameter, dma-ranges and dma-coherent. Update the documentation so that >> its useful for future users. >> >> The "dma-ranges" property is intended to be used for describing the >> configuration of DMA bus RAM addresses and its offset w.r.t CPU addresses. >> >> The "dma-coherent" property is intended to be used for identifying devices >> supported coherent DMA operations. >> >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: Grant Likely <grant.likely@linaro.org> >> Cc: Rob Herring <robh+dt@kernel.org> >> Cc: Pawel Moll <pawel.moll@arm.com> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: Ian Campbell <ijc+devicetree@hellion.org.uk> >> Cc: Shawn Guo <shawn.guo@freescale.com> >> Cc: Kumar Gala <galak@codeaurora.org> >> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> >> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> >> --- >> Documentation/devicetree/booting-without-of.txt | 60 +++++++++++++++++++++++ >> 1 file changed, 60 insertions(+) >> >> diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt >> index 1f013bd..f0120c1 100644 >> --- a/Documentation/devicetree/booting-without-of.txt >> +++ b/Documentation/devicetree/booting-without-of.txt >> @@ -51,6 +51,8 @@ Table of Contents >> >> VIII - Specifying device power management information (sleep property) >> >> + VIV - Specifying dma bus information > > "9" in Roman numeral is "IX" > Yeah.. Not sure what I was thinking... Regards, Santosh
diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt index 1f013bd..f0120c1 100644 --- a/Documentation/devicetree/booting-without-of.txt +++ b/Documentation/devicetree/booting-without-of.txt @@ -51,6 +51,8 @@ Table of Contents VIII - Specifying device power management information (sleep property) + VIV - Specifying dma bus information + Appendix A - Sample SOC node for MPC8540 @@ -1332,6 +1334,64 @@ reasonably grouped in this manner, then create a virtual sleep controller (similar to an interrupt nexus, except that defining a standardized sleep-map should wait until its necessity is demonstrated). +VIV - Specifying dma bus information + +Some devices may have DMA memory range shifted relatively to the beginning of +RAM, or even placed outside of kernel RAM. For example, the Keystone 2 SoC +worked in LPAE mode with 4G memory has: +- RAM range: [0x8 0000 0000, 0x8 FFFF FFFF] +- DMA range: [ 0x8000 0000, 0xFFFF FFFF] +and DMA range is aliased into first 2G of RAM in HW. + +In such cases, DMA addresses translation should be performed between CPU phys +and DMA addresses. The "dma-ranges" property is intended to be used +for describing the configuration of such system in DT. + +In addition, each DMA master device on the DMA bus may or may not support +coherent DMA operations. The "dma-coherent" property is intended to be used +for identifying devices supported coherent DMA operations in DT. + +* DMA Bus master +Optional property: +- dma-ranges: <prop-encoded-array> encoded as arbitrary number of triplets of + (child-bus-address, parent-bus-address, length). Each triplet specified + describes a contiguous DMA address range. + The dma-ranges property is used to describe the direct memory access (DMA) + structure of a memory-mapped bus whose device tree parent can be accessed + from DMA operations originating from the bus. It provides a means of + defining a mapping or translation between the physical address space of + the bus and the physical address space of the parent of the bus. + (for more information see ePAPR specification) + +* DMA Bus child +Optional property: +- dma-ranges: <empty> value. if present - It means that DMA addresses + translation has to be enabled for this device. +- dma-coherent: Present if dma operations are coherent + +Example: +soc { + compatible = "ti,keystone","simple-bus"; + ranges = <0x0 0x0 0x0 0xc0000000>; + dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>; + + [...] + + usb: usb@2680000 { + compatible = "ti,keystone-dwc3"; + + [...] + + dma-coherent; + dma-ranges; + + dwc3@2690000 { + compatible = "synopsys,dwc3"; + [...] + }; + }; +}; + Appendix A - Sample SOC node for MPC8540 ========================================