nvlink: Associate and allocate NPUs using slots

Allocating BDFNs to NPU devices and associating NPU devices with PCI
devices of GPUs both rely on comparing PBCQ handles.  This will fail if a
system has multiple sets of GPUs behind a single PHB.

Rework this to instead use slot locations.  The following changes are
introduced:

 - Groups of NPU links that connect to the same GPU are presented in the
   slot table entries as st_npu_slot, using ST_LOC_NPU_GROUP

 - NPU links are created with the ibm,npu-group-id property replacing the
   ibm,pbcq property, which is used in BDFN allocation and GPU association

 - Slot comparison is handled slightly differently for NPU devices as the
   function of the BDFN is ignored, since the device number represents the
   physical GPU the link is connected to

 - BDFN allocation for NPU devices is now derived from the groups in the
   slot table.  For Garrison, the same BDFNs are generated as before.

 - Association with GPU PCI devices is performed by comparing the slot
   label.  This means for future machines with NPUs that slot labels
   are compulsory to have NVLink functionality working.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-By: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/npu.h b/include/npu.h
index 778c985..800515a 100644
--- a/include/npu.h
+++ b/include/npu.h
@@ -148,6 +148,9 @@ struct npu_dev {
 	uint32_t		procedure_status;
 
 	uint8_t			pe_num;
+
+	/* Used to associate the NPU device with GPU PCI devices */
+	const char		*slot_label;
 };
 
 /* NPU PHB descriptor */