[Skiboot] [PATCH v8 10/10] doc/device-tree: Add OpenCAPI device tree bindings

[Andrew Donnellan]

Suggested-by: Stewart Smith <stewart at linux.vnet.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

---

v7->v8:

  - Add some extra commentary and link to the new PCI device tree
    documentation (Stewart)
---
 doc/device-tree/opencapi.rst | 69 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 69 insertions(+)
 create mode 100644 doc/device-tree/opencapi.rst

diff --git a/doc/device-tree/opencapi.rst b/doc/device-tree/opencapi.rst
new file mode 100644
index 000000000000..b24b29cf8cc7
--- /dev/null
+++ b/doc/device-tree/opencapi.rst
@@ -0,0 +1,69 @@
+.. _device-tree/opencapi:
+
+=============================
+OpenCAPI Device Tree Bindings
+=============================
+
+NPU bindings
+------------
+
+The NPU nodes are similar to those in :doc:`nvlink`.
+
+We distinguish between OpenCAPI and NVLink links using the
+`ibm.npu-link-opencapi` compatible string. NPUs with a mixture of
+OpenCAPI and NVLink links are currently unsupported.
+
+.. code-block:: dts
+
+  xscom at 603fc00000000 {
+    npu at 5011000 {
+      compatible = "ibm,power9-npu";
+      phandle = <0xe6>;
+      ibm,phb-index = <0x7>;
+      reg = <0x5011000 0x2c>;
+      ibm,npu-index = <0x0>;
+      ibm,npu-links = <0x2>; /* Number of links wired up to this npu. */
+
+      link at 2 {
+        compatible = "ibm,npu-link-opencapi";
+        ibm,npu-group-id = <0x1>;
+	ibm,npu-lane-mask = <0xf1e000>; /* Mask specifying which IBM PHY lanes
+	                                 * are used for this link. 24-bit,
+	                                 * lane 0 is most significant bit */
+        ibm,npu-phy = <0x80000000 0x9010c3f>; /* SCOM address of the IBM PHY
+	                                       * controlling this link. */
+	ibm,npu-link-index = <0x2>; /* Hardware link index.
+                                     * Used to calculate various address offsets. */
+	phandle = <0xe7>;
+      };
+
+      link at 3 {
+        compatible = "ibm,npu-link-opencapi";
+	ibm,npu-group-id = <0x2>;
+	ibm,npu-lane-mask = <0x78f>;
+	ibm,npu-phy = <0x80000000 0x9010c3f>;
+	ibm,npu-link-index = <0x3>;
+	phandle = <0xe8>;
+      };
+    };
+  };
+
+PCI device bindings
+-------------------
+
+The PCI devices mostly look like regular PCI devices (see :doc:`pci`),
+but have a few additional fields to allow the devices to be associated
+with the relevant NPU. These fields are presently not consumed by
+anything but may be used in future.
+
+.. code-block:: dts
+
+  pciex at 600e800000000 {
+    /* OpenCAPI specific properties */
+    compatible = "ibm,power9-npu-opencapi-pciex", "ibm,ioda2-npu2-opencapi-phb";
+    ibm,npcq = <0xe6>; /* phandle to the NPU node */
+    ibm,npu-index = <0x0>;
+    ibm,links = <0x1>;
+    /* Generic PCI fields here */
+  }
+
-- 
git-series 0.9.1