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From:   Etienne Carriere <etienne.carriere@linaro.org>
To:     linux-kernel@vger.kernel.org
Cc:     linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        robh+dt@kernel.org, Etienne Carriere <etienne.carriere@linaro.org>
Subject: [RFC PATCH 2/2] dt-bindings: arm: Add secure-resets binding description
Date:   Thu, 23 Apr 2020 08:48:08 +0200
Message-Id: <20200423064808.10468-3-etienne.carriere@linaro.org>
In-Reply-To: <20200423064808.10468-1-etienne.carriere@linaro.org>
References: <20200423064808.10468-1-etienne.carriere@linaro.org>
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Describe how resets property can leverage secure- property prefix
for reset controller assigned to secure or non-secure world.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
---
 .../devicetree/bindings/arm/secure.txt         | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/secure.txt b/Documentation/devicetree/bindings/arm/secure.txt
index 9bc94921f2a6..f0aa6a5fb436 100644
--- a/Documentation/devicetree/bindings/arm/secure.txt
+++ b/Documentation/devicetree/bindings/arm/secure.txt
@@ -72,6 +72,24 @@ Valid Secure world properties
   clocks = <&scmi_clk 2>;	/* NS relies on SCMI resources */
   secure-clocks= <&clk 5>;	/* S accesses the SoC reset interfaces */
 
+- secure-resets : specifies the Phandle list secure world shall use
+  for the related reset controller(s) whereas property "resets" specifies
+  the reset controller Phandle list non-secure shall use. This
+  configuration can apply for example when a hardware reset controller can
+  only be accessed by secure world and this one opens a software service,
+  as a SCMI reset domain, for non-secure world to access the resource when
+  platform assigns the reset control to non-secure world, i.e.:
+
+  resets = <&scmi_rst 0>, <&scmi_rst 1>;
+  secure-resets = <&rst 5>, <&rst 7>;
+  reset-names = "int", "ext";
+
+  Such device description relaxes constraints on device tree modifications
+  when one, a user or a bootloader, needs to assign a resource to secure
+  or non-secure worlds. Indeed, this allows only "status" and "secure-status"
+  to be set while the rest of the device description in the node remains
+  unchanged.
+
 The secure-chosen node
 ----------------------
 
-- 
2.17.1