NTB: Alter Scratchpads API to support multi-ports devices

Even though there is no any real NTB hardware, which would have both more
than two ports and Scratchpad registers, it is logically correct to have
Scratchpad API accepting a peer port index as well. Intel/AMD drivers utilize
Primary and Secondary topology to split Scratchpad between connected root
devices. Since port-index API introduced, Intel/AMD NTB hardware drivers can
use device port to determine which Scratchpad registers actually belong to
local and peer devices. The same approach can be used if some potential
hardware in future will be multi-port and have some set of Scratchpads.
Here are the brief of changes in the API:
 ntb_spad_count() - return number of Scratchpads per each port
 ntb_peer_spad_addr(pidx, sidx) - address of Scratchpad register of the
peer device with pidx-index
 ntb_peer_spad_read(pidx, sidx) - read specified Scratchpad register of the
peer with pidx-index
 ntb_peer_spad_write(pidx, sidx) - write data to Scratchpad register of the
peer with pidx-index

Since there is hardware which doesn't support Scratchpad registers, the
corresponding API methods are now made optional.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

3 files changed, 28 insertions, 7 deletions

diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 7f89cceaf350..42756a98a728 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -518,9 +518,9 @@ static void perf_link_work(struct work_struct *work)
 	if (max_mw_size && size > max_mw_size)
 		size = max_mw_size;
 
-	ntb_peer_spad_write(ndev, MW_SZ_HIGH, upper_32_bits(size));
-	ntb_peer_spad_write(ndev, MW_SZ_LOW, lower_32_bits(size));
-	ntb_peer_spad_write(ndev, VERSION, PERF_VERSION);
+	ntb_peer_spad_write(ndev, PIDX, MW_SZ_HIGH, upper_32_bits(size));
+	ntb_peer_spad_write(ndev, PIDX, MW_SZ_LOW, lower_32_bits(size));
+	ntb_peer_spad_write(ndev, PIDX, VERSION, PERF_VERSION);
 
 	/* now read what peer wrote */
 	val = ntb_spad_read(ndev, VERSION);
diff --git a/drivers/ntb/test/ntb_pingpong.c b/drivers/ntb/test/ntb_pingpong.c
index 12f8b40cb11a..938a18bcfc3f 100644
--- a/drivers/ntb/test/ntb_pingpong.c
+++ b/drivers/ntb/test/ntb_pingpong.c
@@ -138,7 +138,7 @@ static void pp_ping(unsigned long ctx)
 			"Ping bits %#llx read %#x write %#x\n",
 			db_bits, spad_rd, spad_wr);
 
-		ntb_peer_spad_write(pp->ntb, 0, spad_wr);
+		ntb_peer_spad_write(pp->ntb, PIDX, 0, spad_wr);
 		ntb_peer_db_set(pp->ntb, db_bits);
 		ntb_db_clear_mask(pp->ntb, db_mask);
 
@@ -225,6 +225,12 @@ static int pp_probe(struct ntb_client *client,
 		}
 	}
 
+	if (ntb_spad_count(ntb) < 1) {
+		dev_dbg(&ntb->dev, "no enough scratchpads\n");
+		rc = -EINVAL;
+		goto err_pp;
+	}
+
 	if (ntb_spad_is_unsafe(ntb)) {
 		dev_dbg(&ntb->dev, "scratchpad is unsafe\n");
 		if (!unsafe) {
diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
index cb692473d457..f002bf48a08d 100644
--- a/drivers/ntb/test/ntb_tool.c
+++ b/drivers/ntb/test/ntb_tool.c
@@ -462,13 +462,22 @@ static TOOL_FOPS_RDWR(tool_spad_fops,
 		      tool_spad_read,
 		      tool_spad_write);
 
+static u32 ntb_tool_peer_spad_read(struct ntb_dev *ntb, int sidx)
+{
+	return ntb_peer_spad_read(ntb, PIDX, sidx);
+}
+
 static ssize_t tool_peer_spad_read(struct file *filep, char __user *ubuf,
 				   size_t size, loff_t *offp)
 {
 	struct tool_ctx *tc = filep->private_data;
 
-	return tool_spadfn_read(tc, ubuf, size, offp,
-				tc->ntb->ops->peer_spad_read);
+	return tool_spadfn_read(tc, ubuf, size, offp, ntb_tool_peer_spad_read);
+}
+
+static int ntb_tool_peer_spad_write(struct ntb_dev *ntb, int sidx, u32 val)
+{
+	return ntb_peer_spad_write(ntb, PIDX, sidx, val);
 }
 
 static ssize_t tool_peer_spad_write(struct file *filep, const char __user *ubuf,
@@ -477,7 +486,7 @@ static ssize_t tool_peer_spad_write(struct file *filep, const char __user *ubuf,
 	struct tool_ctx *tc = filep->private_data;
 
 	return tool_spadfn_write(tc, ubuf, size, offp,
-				 tc->ntb->ops->peer_spad_write);
+				 ntb_tool_peer_spad_write);
 }
 
 static TOOL_FOPS_RDWR(tool_peer_spad_fops,
@@ -926,6 +935,12 @@ static int tool_probe(struct ntb_client *self, struct ntb_dev *ntb)
 		goto err_tc;
 	}
 
+	if (ntb_spad_count(ntb) < 1) {
+		dev_dbg(&ntb->dev, "no enough scratchpads\n");
+		rc = -EINVAL;
+		goto err_tc;
+	}
+
 	if (ntb_db_is_unsafe(ntb))
 		dev_dbg(&ntb->dev, "doorbell is unsafe\n");