Re: [Patch v15 4/5] dt-bindings: arm-smmu: Add bindings for qcom,smmu-v2
From: Vivek Gautam
Date: Wed Aug 29 2018 - 04:35:24 EST
Hi Rob,
On 8/29/2018 2:04 AM, Rob Herring wrote:
On Mon, Aug 27, 2018 at 04:25:50PM +0530, Vivek Gautam wrote:
Add bindings doc for Qcom's smmu-v2 implementation.
Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
Changes since v14:
- This is a new patch added in v15 after noticing the new
checkpatch warning for separate dt-bindings doc.
- This patch also addresses comments given by Rob and Robin to add
a list of valid values of '<soc>' in "qcom,<soc>-smmu-v2"
compatible string.
.../devicetree/bindings/iommu/arm,smmu.txt | 47 ++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
index 8a6ffce12af5..52198a539606 100644
--- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
+++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
@@ -17,10 +17,24 @@ conditions.
"arm,mmu-401"
"arm,mmu-500"
"cavium,smmu-v2"
+ "qcom,<soc>-smmu-v2", "qcom,smmu-v2"
The v2 in the compatible string is kind of redundant unless the SoC has
other SMMU types.
sdm845 has smmu-v2, and smmu-500 [1].
depending on the particular implementation and/or the
version of the architecture implemented.
+ A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
+ "qcom,<soc>-smmu-v2" represents a soc specific compatible
+ string that should be present along with the "qcom,smmu-v2"
+ to facilitate SoC specific clocks/power connections and to
+ address specific bug fixes.
+ '<soc>' string in "qcom,<soc>-smmu-v2" should be one of the
+ following:
+ msm8996 - for msm8996 Qcom SoC.
+ sdm845 - for sdm845 Qcom Soc.
Rather than all this prose, it would be simpler to just add 2 lines with
the full compatibles rather than <soc>. The <soc> thing is not going to
work when/if we move bindings to json-schema also.
then we keep adding
ÂÂÂÂÂÂÂÂ "qcom,msm8996-smmu-v2", "qcom,smmu-v2"
ÂÂÂÂÂÂÂÂ "qcom,msm8998-smmu-v2", "qcom,smmu-v2"
ÂÂÂÂÂÂÂÂ "qcom,sdm845-smmu-v2", "qcom,smmu-v2",
and from [1]
ÂÂÂÂÂÂÂÂ "qcom,sdm845-smmu-500", "arm,mmu-500", etc.
for each SoCs?
+
+ An example string would be -
+ "qcom,msm8996-smmu-v2", "qcom,smmu-v2".
+
- reg : Base address and size of the SMMU.
- #global-interrupts : The number of global interrupts exposed by the
@@ -71,6 +85,22 @@ conditions.
or using stream matching with #iommu-cells = <2>, and
may be ignored if present in such cases.
+- clock-names: List of the names of clocks input to the device. The
+ required list depends on particular implementation and
+ is as follows:
+ - for "qcom,smmu-v2":
+ - "bus": clock required for downstream bus access and
+ for the smmu ptw,
+ - "iface": clock required to access smmu's registers
+ through the TCU's programming interface.
+ - unspecified for other implementations.
+
+- clocks: Specifiers for all clocks listed in the clock-names property,
+ as per generic clock bindings.
+
+- power-domains: Specifiers for power domains required to be powered on for
+ the SMMU to operate, as per generic power domain bindings.
+
** Deprecated properties:
- mmu-masters (deprecated in favour of the generic "iommus" binding) :
@@ -137,3 +167,20 @@ conditions.
iommu-map = <0 &smmu3 0 0x400>;
...
};
+
+ /* Qcom's arm,smmu-v2 implementation */
+ smmu4: iommu {
Needs a unit-address.
I went in symmetry with another example in this file for 'smmu1'. I will
add the address here.
And if you would like, I can squash a change for 'smmu1' too in this
patch, although that will be trivial.
[1] https://patchwork.kernel.org/patch/10565291/
Best regards
Vivek
[snip]