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| author | Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com> | 2026-06-08 22:44:24 +0200 |
|---|---|---|
| committer | Lee Jones <lee@kernel.org> | 2026-07-30 14:32:31 +0100 |
| commit | 39268dbd7bc7feecb684b7f84eb20efaf2241ff1 (patch) | |
| tree | 2de63f095d55dba7fc5e15aab3b54c02f5d8d76a | |
| parent | f1f3afd19fca9e7f43cbcc1efaf60c365226c1ca (diff) | |
| download | linux-39268dbd7bc7feecb684b7f84eb20efaf2241ff1.tar.gz linux-39268dbd7bc7feecb684b7f84eb20efaf2241ff1.zip | |
dt-bindings: mfd: syscon: Disallow simple-bus with syscon
"syscon" is a system controller with registers having their own
functions, thus not really a trivial MMIO simple bus. "simple-bus" on
the other hand is just a bus on which multiple devices sit and the
"simple" means no functions are allowed here.
Combination of both "syscon" and "simple-bus" is abuse of DT for easier
instantiating of Linux device drivers so add a schema to disallow that.
Unfortunately there are a few old cases of that patterns, so add
exceptions:
1. "cznic,turris1x-cpld" and "img,pistachio-cr-periph" are already used
in upstream DTS.
2. TI has several DTSI with a child of SCM device (e.g. "ti,am3-scm")
using "syscon" and "simple-bus" but without a dedicated compatible
documented anywhere. Add new compatibles for such cases.
Additionally, add comments around code enforcing two or three
compatibles: it is similar safeguard detecting incorrect bindings.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260608-n-dt-bindings-simple-bus-syscon-v3-1-4eba9ec1212a@oss.qualcomm.com
Signed-off-by: Lee Jones <lee@kernel.org>
| -rw-r--r-- | Documentation/devicetree/bindings/mfd/syscon-common.yaml | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mfd/syscon-common.yaml b/Documentation/devicetree/bindings/mfd/syscon-common.yaml index 14a08e7bc8bd..2d5eef5add54 100644 --- a/Documentation/devicetree/bindings/mfd/syscon-common.yaml +++ b/Documentation/devicetree/bindings/mfd/syscon-common.yaml @@ -32,6 +32,7 @@ properties: compatible: contains: const: syscon + # Always require a specific compatible for syscon minItems: 2 maxItems: 5 # Should be enough @@ -52,11 +53,44 @@ allOf: contains: const: simple-mfd then: + # Always require a specific compatible for syscon with simple-mfd properties: compatible: minItems: 3 maxItems: 5 + - if: + properties: + compatible: + contains: + const: simple-bus + then: + # simple-bus conflicts with syscon - if a device is a system controller + # with miscellaneous registers, then it has at least one dedicated + # function thus it is not a simple bus. Allow existing exceptions. + if: + properties: + compatible: + not: + contains: + # This list CANNOT grow + enum: + - cznic,turris1x-cpld + - img,pistachio-cr-periph + - ti,am3352-scm-conf + - ti,am4372-scm-conf + - ti,dm814-scm-conf + - ti,dm8168-scm-conf + - ti,dra7-scm-conf + - ti,omap2-scm-conf + - ti,omap3-scm-conf + - ti,omap4-sysc-padconf-global + - ti,omap5-scm-wkup-conf + - ti,omap5-sysc-padconf-global + then: + required: + - incorrect-usage-of-simple-bus-and-syscon + additionalProperties: true examples: |