ntb_hw_switchtec: Allow using Switchtec NTB in multi-partition setups

Allow using Switchtec NTB in setups that have more than two partitions.
Note: this does not enable having multi-host communication, it only
allows for a single NTB link between two hosts in a network that might
have more than two.

Use following logic to determine the NT peer partition:

1) If there are 2 partitions, and the target vector is set in
   the Switchtec configuration, use the partition specified in target
   vector.
2) If there are 2 partitions and target vector is unset
   use the only other partition as specified in the NT EP map.
3) If there are more than 2 partitions and target vector is set
   use the other partition specified in target vector.
4) If there are more than 2 partitions and target vector is unset,
   this is invalid and report an error.

Signed-off-by: Kelvin Cao <kelvin.cao@microsemi.com>
[logang@deltatee.com: commit message fleshed out]
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/switchtec.h b/include/linux/switchtec.h
index 09d73d0d1aa8..d4a7c18b42cf 100644
--- a/include/linux/switchtec.h
+++ b/include/linux/switchtec.h
@@ -168,6 +168,14 @@ struct ntb_info_regs {
 	u16 reserved1;
 	u64 ep_map;
 	u16 requester_id;
+	u16 reserved2;
+	u32 reserved3[4];
+	struct nt_partition_info {
+		u32 xlink_enabled;
+		u32 target_part_low;
+		u32 target_part_high;
+		u32 reserved;
+	} ntp_info[48];
 } __packed;
 
 struct part_cfg_regs {