On Fri, Feb 22, 2019 at 10:43 PM Rob Herring [off-list ref] wrote:

On Thu, Feb 21, 2019 at 04:47:24PM +0800, Pi-Hsun Shih wrote:

quoted

From: Erin Lo <redacted>

Add a DT binding documentation of SCP for the
MT8183 SoC from Mediatek.

Signed-off-by: Erin Lo <redacted>
---
Changes from v4:
 - Add detail of more properties.
 - Document the usage of mtk,rpmsg-name in subnode from the new design.

Changes from v3:
 - No change.

Changes from v2:
 - No change. I realized that for this patch series, there's no need to
   add anything under the mt8183-scp node (neither the mt8183-rpmsg or
   the cros-ec-rpmsg) for them to work, since mt8183-rpmsg is added
   directly as a rproc_subdev by code, and cros-ec-rpmsg is dynamically
   created by SCP name service.

Changes from v1:
 - No change.
---
 .../bindings/remoteproc/mtk,scp.txt           | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/remoteproc/mtk,scp.txt

diff --git a/Documentation/devicetree/bindings/remoteproc/mtk,scp.txt b/Documentation/devicetree/bindings/remoteproc/mtk,scp.txt
new file mode 100644
index 00000000000000..8cf8b0e0d98a4c
--- /dev/null
+++ b/Documentation/devicetree/bindings/remoteproc/mtk,scp.txt

@@ -0,0 +1,37 @@
+Mediatek SCP Bindings
+----------------------------------------
+
+This binding provides support for ARM Cortex M4 Co-processor found on some
+Mediatek SoCs.
+
+Required properties:
+- compatible         Should be "mediatek,mt8183-scp"
+- reg                        Should contain the address ranges for the two memory
+                     regions, SRAM and CFG.
+- reg-names          Contains the corresponding names for the two memory
+                     regions. These should be named "sram" & "cfg".
+- clocks             Clock for co-processor (See: ../clock/clock-bindings.txt)
+- clock-names                Contains the corresponding name for the clock. This
+                     should be named "main".
+
+Subnodes
+--------
+
+When CONFIG_RPMSG_MTK_SCP is enabled, subnodes of the SCP represent rpmsg

Bindings can't depend on kernel config options.

What's the recommendation here if the subnode only has effect when the
config is enabled? Should I just skip the sentence "When ... is
enabled"?

quoted

+devices. The names of the devices are not important. The properties of these
+nodes are defined by the individual bindings for the rpmsg devices - but must
+contain the following property:
+
+- mtk,rpmsg-name     Contains the name for the rpmsg device. Used to match
+                     the subnode to rpmsg device announced by SCP.

I don't think this belongs in DT, but without some examples I'm not
really sure.

This is similar to the qcom,smd-channels property in
Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt, a example DT
for this:

scp {
        compatible = "mediatek,mt8183-scp";
        ...
        cros_ec {
                compatible = "google,cros-ec-rpmsg";
                mtk,rpmsg-name = "cros-ec-rpmsg";

                cros_ec_codec {
                        compatible = "google,cros-ec-codec";
                        ...
                };
        };
};

quoted

+
+Example:
+
+     scp: scp@10500000 {
+             compatible = "mediatek,mt8183-scp";
+             reg = <0 0x10500000 0 0x80000>,
+                   <0 0x105c0000 0 0x5000>;
+             reg-names = "sram", "cfg";
+             clocks = <&infracfg CLK_INFRA_SCPSYS>;
+             clock-names = "main";
+     };
--
2.21.0.rc0.258.g878e2cd30e-goog

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