hw/npu2: Fix OpenCAPI PE assignment

When we support mixing NVLink and OpenCAPI devices on the same NPU, we're
going to have to share the same range of 16 PE numbers between NVLink and
OpenCAPI PHBs.

For OpenCAPI devices, PE assignment is only significant for determining
which System Interrupt Log register is used for a particular brick - unlike
NVLink, it doesn't play any role in determining how links are fenced.

Split the PE range into a lower half which is used for NVLink, and an upper
half that is used for OpenCAPI, with a fixed PE number assigned per brick.

As the PE assignment for OpenCAPI devices is fixed, set the PE once
during device init and then ignore calls to the set_pe() operation.

Suggested-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/include/npu2.h b/include/npu2.h
index a2bcc450..86a449eb 100644
--- a/include/npu2.h
+++ b/include/npu2.h
@@ -46,9 +46,24 @@
 					  dev->npu->chip_id, dev->brick_index, ## a)
 
 
-/* Number of PEs supported */
-#define NPU2_MAX_PE_NUM		16
-#define NPU2_RESERVED_PE_NUM	15
+/*
+ * Number of PEs supported
+ *
+ * The NPU supports PE numbers from 0-15. At present, we only assign a maximum
+ * of 1 PE per brick.
+ *
+ * NVLink devices are currently exposed to Linux underneath a single virtual
+ * PHB. Therefore, we give NVLink half the available PEs, which is enough for
+ * 6 bricks plus 1 reserved PE.
+ *
+ * For OpenCAPI, the BDF-to-PE registers are used exclusively for mapping
+ * bricks to System Interrupt Log registers (the BDF component of those
+ * registers is ignored). Currently, we allocate a fixed PE based on the brick
+ * index in the upper half of the PE namespace.
+ */
+#define NPU2_MAX_PE_NUM		8
+#define NPU2_RESERVED_PE_NUM	7
+#define NPU2_OCAPI_PE(ndev) ((ndev)->brick_index + NPU2_MAX_PE_NUM)
 
 #define NPU2_LINKS_PER_CHIP 6