ntb_transport: Check the number of spads the hardware supports

I'm working on hardware that currently has a limited number of
scratchpad registers and ntb_ndev fails with no clue as to why. I
feel it is better to fail early and provide a reasonable error message
then to fail later on.

The same is done to ntb_perf, but it doesn't currently require enough
spads to actually fail. I've also removed the unused SPAD_MSG and
SPAD_ACK enums so that MAX_SPAD accurately reflects the number of
spads used.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

2 files changed, 13 insertions, 4 deletions

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 6db8c8528f26..d5c5894f252e 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1060,6 +1060,13 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
         int node;
         int rc, i;
 
+        mw_count = ntb_mw_count(ndev);
+        if (ntb_spad_count(ndev) < (NUM_MWS + 1 + mw_count * 2)) {
+                dev_err(&ndev->dev, "Not enough scratch pad registers for %s",
+                        NTB_TRANSPORT_NAME);
+                return -EIO;
+        }
+
         if (ntb_db_is_unsafe(ndev))
                 dev_dbg(&ndev->dev,
                         "doorbell is unsafe, proceed anyway...\n");
@@ -1075,8 +1082,6 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
 
         nt->ndev = ndev;
 
-        mw_count = ntb_mw_count(ndev);
-
         nt->mw_count = mw_count;
 
         nt->mw_vec = kzalloc_node(mw_count * sizeof(*nt->mw_vec),
diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 30635c89320c..4368519da102 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -143,8 +143,6 @@ enum {
         VERSION = 0,
         MW_SZ_HIGH,
         MW_SZ_LOW,
-        SPAD_MSG,
-        SPAD_ACK,
         MAX_SPAD
 };
 
@@ -696,6 +694,12 @@ static int perf_probe(struct ntb_client *client, struct ntb_dev *ntb)
         int node;
         int rc = 0;
 
+        if (ntb_spad_count(ntb) < MAX_SPAD) {
+                dev_err(&ntb->dev, "Not enough scratch pad registers for %s",
+                        DRIVER_NAME);
+                return -EIO;
+        }
+
         node = dev_to_node(&pdev->dev);
 
         perf = kzalloc_node(sizeof(*perf), GFP_KERNEL, node);