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, 8 insertions, 0 deletions

diff --git a/platforms/astbmc/astbmc.h b/platforms/astbmc/astbmc.h
index 23c31c7..322282e 100644
--- a/platforms/astbmc/astbmc.h
+++ b/platforms/astbmc/astbmc.h
@@ -20,6 +20,13 @@
 
 #define ST_LOC_PHB(chip_id, phb_idx)    ((chip_id) << 16 | (phb_idx))
 #define ST_LOC_DEVFN(dev, fn)	        ((dev) << 3 | (fn))
+/*
+ * NPU groups are used to allocate device numbers.  There is a 1 to 1
+ * correlation between a NPU group and a physical GPU.  Links within a group
+ * are allocated as functions within a device, so groups must be numbered
+ * sequentially starting at 0.
+ */
+#define ST_LOC_NPU_GROUP(group_id)	(group_id << 3)
 
 struct slot_table_entry {
 	enum slot_table_etype {
@@ -27,6 +34,7 @@ struct slot_table_entry {
 		st_phb,
 		st_pluggable_slot,
 		st_builtin_dev,
+		st_npu_slot
 	} etype;
 	uint32_t location;
 	const char *name;