On 07/23/2015 09:52 AM, Mark Rutland wrote:
[...]
+MSI clients
+===========
+
+MSI clients are devices which generate MSIs. For each MSI they wish to
+generate, the doorbell and payload may be configured, though sideband
+information may not be configurable.
+
+Required properties:
+--------------------
+
+- msi-parent: A list of phandle + msi-specifier pairs, one for each MSI
+ controller which the device is capable of using.
+
We say here that "msi-parent" consists of pairs ...
+ This property is unordered, and MSIs may be allocated from any combination of
+ MSI controllers listed in the msi-parent property.
+
+ If a device has restrictions on the allocation of MSIs, these restrictions
+ must be described with additional properties.
+
+ When #msi-cells is non-zero, busses with an msi-parent will require
+ additional properties to describe the relationship between devices on the bus
+ and the set of MSIs they can potentially generate.
+
+
+Example
+=======
+
+/ {
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ msi_a: msi-controller@a {
+ reg = <0xa 0xf00>;
+ compatible = "vendor-a,some-controller";
+ msi-controller;
+ /* No sideband data, so #msi-cells omitted */
+ };
+
+ msi_b: msi-controller@b {
+ reg = <0xb 0xf00>;
+ compatible = "vendor-b,another-controller";
+ msi-controller;
+ /* Each device has some unique ID */
+ #msi-cells = <1>;
+ };
+
+ msi_c: msi-controller@c {
+ reg = <0xb 0xf00>;
+ compatible = "vendor-b,another-controller";
+ msi-controller;
+ /* Each device has some unique ID */
+ #msi-cells = <1>;
+ };
+
+ dev@0 {
+ reg = <0x0 0xf00>;
+ compatible = "vendor-c,some-device";
+
+ /* Can only generate MSIs to msi_a */
+ msi-parent = <&msi_a>;
My device-tree syntax foo is a little rusty, but doesn't "msi-parent"
need a pair of elements? This has only the phandle.
+ };
+
+ dev@1 {
+ reg = <0x1 0xf00>;
+ compatible = "vendor-c,some-device";
+
+ /*
+ * Can generate MSIs to either A or B.
+ */
+ msi-parent = <&msi_a>, <&msi_b 0x17>;
... same here, ...
+ };
+
+ dev@2 {
+ reg = <0x2 0xf00>;
+ compatible = "vendor-c,some-device";
+ /*
+ * Has different IDs at each MSI controller.
+ * Can generate MSIs to all of the MSI controllers.
+ */
+ msi-parent = <&msi_a>, <&msi_b 0x17>, <&msi_c 0x53>;
... and here
+ };
+};
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