Re: [RFC PATCH v1 2/2] perf/smmuv3: To support the dts to get options

On Tue, Jul 07, 2020 at 05:01:14PM +0200, Jean-Philippe Brucker wrote:

Hi,

On Mon, Jul 06, 2020 at 04:03:34PM +0100, Robin Murphy wrote:

quoted

On 2020-07-06 12:22, Jay Chen wrote:

quoted

For the smmuv3 pmu for support the dts to get the
options

Signed-off-by: Jay Chen <redacted>

[...]

quoted

quoted

+static const struct of_device_id smmu_pmu_of_match[] = {
+	{ .compatible = "arm-smmu-v3-pmcg", },

Please define the DT binding first. IIRC Jean-Philippe wrote some patches a
while back that never got posted, but I suppose it should be YAML now...

Yes, I've never followed through with that because it only supported the
RevC FastModel with non-default model parameters. I attached the binding I
currently have, converted to YAML.

Thanks,
Jean

quoted

From b117e5b4ce96a5a8327333ab408cf61200850d4f Mon Sep 17 00:00:00 2001

From: Jean-Philippe Brucker <redacted>
Date: Tue, 7 Jul 2020 16:55:16 +0200
Subject: [PATCH] dt-bindings: Add SMMUv3 PMCG binding

Add binding for the SMMUv3 PMU. Each node represents a PMCG, and is placed
as a sibling node of the SMMU. As PMCGs are mainly implementation
defined there is no 1-1 relation between SMMU and PMCG. The SMMU could
have PMU counters for the TCU and each TBU, or a single PMCG.

TODO: although the Linux implementation doesn't need them, it'd be nice
to have links from the PMCG node to its associated SMMU. IORT does offer
this (Node reference) and perhaps it could later help users figure out
which PMCG is which on systems with dozens of SMMU.

Is the PMCG really a separate block or a new node is just convenient to 
instantiate a driver?

Dual license new bindings.

+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iommu/arm,smmu-v3-pmcg.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ARM SMMUv3 Performance Monitor Counter Group
+
+maintainers:
+  - Will Deacon [off-list ref]
+  - Robin Murphy [off-list ref]
+
+description: |+
+  An SMMUv3 may have several Performance Monitor Counter Group (PMCG).
+  They are standalone performance monitoring units that support both
+  architected and IMPLEMENTATION DEFINED event counters.
+
+properties:
+  $nodename:
+    pattern: "^smmu-pmcg@[0-9a-f]*"

Should be generic:

pmu@...

(or whatever we've used for PMUs).

+  compatible:
+    const: arm,smmu-v3-pmcg

This is correct, but doesn't match the driver.

+
+  reg:
+    minItems: 1
+    maxItems: 2

More than 1 entry needs a description of what each one is.

A variable number of 'reg' entries generally implies more than 1 
compatible unless the 2nd entry is optional.

+
+  interrupts:
+    maxItems: 1
+
+  msi-parent: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |+
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    tcu: smmu-pmcg@2b420000 {

Drop unused labels.

+            compatible = "arm,smmu-v3-pmcg";
+            reg = <0 0x2b420000 0 0x1000>,
+                  <0 0x2b430000 0 0x1000>;
+            interrupts = <GIC_SPI 80 IRQ_TYPE_EDGE_RISING>;
+            msi-parent = <&its 0xff0000>;
+    };
+
+    tbu0: smmu-pmcg@2b440000 {
+            compatible = "arm,smmu-v3-pmcg";
+            reg = <0 0x2b440000 0 0x1000>,
+                  <0 0x2b450000 0 0x1000>;
+            interrupts = <GIC_SPI 81 IRQ_TYPE_EDGE_RISING>;
+            msi-parent = <&its 0xff0000>;
+    };
-- 
2.27.0

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