Re: [PATCH V4 5/6] iommu/arm-smmu: Add support for MMU40x/500 clocks

[Vivek Gautam]

Hi Rob,


On 07/10/2017 09:07 AM, Rob Herring wrote:
> On Thu, Jul 06, 2017 at 03:07:04PM +0530, Vivek Gautam wrote:
> > From: Sricharan R<sricharan@xxxxxxxxxxxxxx>
> >
> > The MMU400x/500 is the implementation of the SMMUv2
> > arch specification. It is split in to two blocks
> > TBU, TCU. TBU caches the page table, instantiated
> > for each master locally, clocked by the TBUn_clk.
> > TCU manages the address translation with PTW and has
> > the programming interface as well, clocked using the
> > TCU_CLK. The TBU can also be sharing the same clock
> > domain as TCU, in which case both are clocked using
> > the TCU_CLK.
> No TBU clock below. When is it shared or not? If that's an integration
> option then the binding should always have a TBU clock with the same
> parent as the TCU_CLK.

Right. This is something that the ARM spec also says.
The TBU clock can either be in the same clock and power domain as
the TCU clock, or in a separate.

As you said, we should have the TBU clock as well, and based on the
integration the TBU clock can either have same parent as TCU or
different.

I will change these bindings to include the TBU clock as well.


Best Regards
Vivek

> > This defines the clock bindings for the same and adds
> > the clock names to compatible data.
> >
> > Signed-off-by: Sricharan R<sricharan@xxxxxxxxxxxxxx>
> > [vivek: clock rework and cleanup]
> > Signed-off-by: Vivek Gautam<vivek.gautam@xxxxxxxxxxxxxx>
> > ---
> >   .../devicetree/bindings/iommu/arm,smmu.txt         | 24 ++++++++++++++++++++++
> >   drivers/iommu/arm-smmu.c                           | 12 ++++++++++-
> >   2 files changed, 35 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > index 8a6ffce12af5..00331752d355 100644
> > --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > @@ -71,6 +71,26 @@ conditions.
> >                     or using stream matching with #iommu-cells = <2>, and
> >                     may be ignored if present in such cases.
> >   
> > +- clock-names:    Should be "tcu" and "iface" for "arm,mmu-400",
> > +                  "arm,mmu-401" and "arm,mmu-500"
> > +
> > +                  "tcu" clock is required for smmu's register access using the
> > +                  programming interface and ptw for downstream bus access. This
> > +                  clock is also used for access to the TBU connected to the
> > +                  master locally. Sometimes however, TBU is clocked along with
> > +                  the master.
> > +
> > +                  "iface" clock is required to access the TCU's programming
> > +                  interface, apart from the "tcu" clock.
> > +
> > +- clocks:         Phandles for respective clocks described by clock-names.
> > +
> > +- power-domains:  Phandles to SMMU's power domain specifier. This is
> > +                  required even if SMMU belongs to the master's power
> > +                  domain, as the SMMU will have to be enabled and
> > +                  accessed before master gets enabled and linked to its
> > +                  SMMU.
> > +
> >   ** Deprecated properties:
> >   
> >   - mmu-masters (deprecated in favour of the generic "iommus" binding) :
> > @@ -95,6 +115,10 @@ conditions.
> >                                <0 36 4>,
> >                                <0 37 4>;
> >                   #iommu-cells = <1>;
> > +                clocks = <&gcc GCC_SMMU_CFG_CLK>,
> > +                         <&gcc GCC_APSS_TCU_CLK>;
> > +
> > +		clock-names = "iface", "tcu";
> >           };
> >   
> >           /* device with two stream IDs, 0 and 7 */
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> > index 75567d9698ab..7bb09280fa11 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -1947,9 +1947,19 @@ struct arm_smmu_match_data {
> >   ARM_SMMU_MATCH_DATA(smmu_generic_v1, ARM_SMMU_V1, GENERIC_SMMU);
> >   ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU);
> >   ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> > -ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> >   ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
> >   
> > +static const char * const arm_mmu500_clks[] = {
> > +	"tcu", "iface",
> > +};
> > +
> > +static const struct arm_smmu_match_data arm_mmu500 = {
> > +	.version = ARM_SMMU_V2,
> > +	.model = ARM_MMU500,
> > +	.clks = arm_mmu500_clks,
> > +	.num_clks = ARRAY_SIZE(arm_mmu500_clks),
> > +};
> > +
> >   static const struct of_device_id arm_smmu_of_match[] = {
> >   	{ .compatible = "arm,smmu-v1", .data = &smmu_generic_v1 },
> >   	{ .compatible = "arm,smmu-v2", .data = &smmu_generic_v2 },
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project
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