dt-bindings: arm: fsl: Add msi-map device-tree binding for fsl-mc bus

The existing bindings cannot be used to specify the relationship
between fsl-mc devices and GIC ITSes.
Add a generic binding for mapping fsl-mc devices to GIC ITSes, using
msi-map property.
In addition, deprecate msi-parent property which no longer makes sense
now that we support translating the MSIs.

Signed-off-by: Laurentiu Tudor <[e-mail]>
Signed-off-by: Diana Craciun <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Cc: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Catalin Marinas <[e-mail]>

Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt

···
 For arm-smmu binding, see:
 Documentation/devicetree/bindings/iommu/arm,smmu.yaml.
 
+The MSI writes are accompanied by sideband data which is derived from the ICID.
+The msi-map property is used to associate the devices with both the ITS
+controller and the sideband data which accompanies the writes.
+
+For generic MSI bindings, see
+Documentation/devicetree/bindings/interrupt-controller/msi.txt.
+
+For GICv3 and GIC ITS bindings, see:
+Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.yaml.
+
 Required properties:
 
     - compatible
···
                        -the second region is the MC control registers. This
                         region may not be present in some scenarios, such
                         as in the device tree presented to a virtual machine.
-
-    - msi-parent
-        Value type: <phandle>
-        Definition: Must be present and point to the MSI controller node
-                    handling message interrupts for the MC.
 
     - ranges
         Value type: <prop-encoded-array>
···
   associated with the listed IOMMU, with the iommu-specifier
   (i - icid-base + iommu-base).
 
+- msi-map: Maps an ICID to a GIC ITS and associated msi-specifier
+  data.
+
+  The property is an arbitrary number of tuples of
+  (icid-base,gic-its,msi-base,length).
+
+  Any ICID in the interval [icid-base, icid-base + length) is
+  associated with the listed GIC ITS, with the msi-specifier
+  (i - icid-base + msi-base).
+
+Deprecated properties:
+
+    - msi-parent
+        Value type: <phandle>
+        Definition: Describes the MSI controller node handling message
+                    interrupts for the MC. When there is no translation
+                    between the ICID and deviceID this property can be used
+                    to describe the MSI controller used by the devices on the
+                    mc-bus.
+                    The use of this property for mc-bus is deprecated. Please
+                    use msi-map.
+
 Example:
 
         smmu: iommu@5000000 {
···
                ...
         };
 
+        gic: interrupt-controller@6000000 {
+               compatible = "arm,gic-v3";
+               ...
+        }
+        its: gic-its@6020000 {
+               compatible = "arm,gic-v3-its";
+               msi-controller;
+               ...
+        };
+
         fsl_mc: fsl-mc@80c000000 {
                 compatible = "fsl,qoriq-mc";
                 reg = <0x00000008 0x0c000000 0 0x40>,    /* MC portal base */
                       <0x00000000 0x08340000 0 0x40000>; /* MC control reg */
-                msi-parent = <&its>;
                 /* define map for ICIDs 23-64 */
                 iommu-map = <23 &smmu 23 41>;
+                /* define msi map for ICIDs 23-64 */
+                msi-map = <23 &its 23 41>;
                 #address-cells = <3>;
                 #size-cells = <1>;