Re: [PATCH v2 03/17] dt-bindings: soc/microchip: make systemcontroller a mfd

On Tuesday, December 21st, 2021 at 17:55, Rob Herring [off-list ref] wrote:

On Fri, Dec 17, 2021 at 09:33:11AM +0000, conor.dooley@microchip.com wrote:

quoted

From: Conor Dooley <conor.dooley@microchip.com>

Make the system controller on the Polarfire SoC
a "simple,mfd" so that the services can be child
nodes of the system controller node.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
 .../microchip,mpfs-sys-controller.yaml        | 33 +++++++++++++++++--
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-sys-controller.yaml b/>Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-sys-controller.yaml
index f699772fedf3..014cb44b8f31 100644
--- a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-sys-controller.yaml
+++ b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-sys-controller.yaml

@@ -13,13 +13,34 @@ description: |
   The PolarFire SoC system controller is communicated with via a mailbox.
   This document describes the bindings for the client portion of that mailbox.

-
 properties:
   mboxes:
     maxItems: 1

   compatible:
-    const: microchip,mpfs-sys-controller
+    items:
+      - const: microchip,mpfs-sys-controller
+      - const: simple-mfd

'simple-mfd' means there is zero dependency on the parent for the child
nodes. Isn't 'mboxes' a dependency?

I suppose it is. I was going off what had been done for the bcm2835
firmware for the rpi its also a mailbox providing "services".
(arm/bcm/raspberrypi,bcm2835-firmware.yaml)

quoted

+
+  hwrandom:
+    type: object
+
+    properties:
+      compatible:
+        const: microchip,mpfs-rng
+
+    required:
+      - compatible
+
+  sysserv:
+    type: object
+
+    properties:
+      compatible:
+        const: microchip,mpfs-generic-service
+
+    required:
+      - compatible

There's not really any need to have child nodes which have no resources.
The driver for microchip,mpfs-sys-controller can create child devices.

I am assuming by this you mean say, take a list of boolean properties and
convert those into child devices? There's a fairly decent number of services
provided by the system controller and these children just represent the
subset that we've implemented so far.

Conor

Rob