ntb_tool: Add link status and files to debugfs

In order to more successfully script with ntb_tool it's useful to
have a link file to check the link status so that the script
doesn't use the other files until the link is up.

This commit adds a 'link' file to the debugfs directory which reads
boolean (Y or N) depending on the link status. Writing to the file
change the link state using ntb_link_enable or ntb_link_disable.

A 'link_event' file is also provided so an application can block until
the link changes to the desired state. If the user writes a 1, it will
block until the link is up. If the user writes a 0, it will block until
the link is down.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

drivers/ntb/test/ntb_tool.c

@@ -59,6 +59,12 @@
  *
  * Eg: check if clearing the doorbell mask generates an interrupt.
  *
+ * # Check the link status
+ * root@self# cat $DBG_DIR/link
+ *
+ * # Block until the link is up
+ * root@self# echo Y > $DBG_DIR/link_event
+ *
  * # Set the doorbell mask
  * root@self# echo 's 1' > $DBG_DIR/mask
  *
@@ -131,6 +137,7 @@ struct tool_mw {
 struct tool_ctx {
 	struct ntb_dev *ntb;
 	struct dentry *dbgfs;
+	wait_queue_head_t link_wq;
 	int mw_count;
 	struct tool_mw mws[MAX_MWS];
 };
@@ -159,6 +166,7 @@ static void tool_link_event(void *ctx)
 	dev_dbg(&tc->ntb->dev, "link is %s speed %d width %d\n",
 		up ? "up" : "down", speed, width);
 
+	wake_up(&tc->link_wq);
 }
 
 static void tool_db_event(void *ctx, int vec)
@@ -473,6 +481,83 @@ static TOOL_FOPS_RDWR(tool_peer_spad_fops,
 		      tool_peer_spad_read,
 		      tool_peer_spad_write);
 
+static ssize_t tool_link_read(struct file *filep, char __user *ubuf,
+			      size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+	char buf[3];
+
+	buf[0] = ntb_link_is_up(tc->ntb, NULL, NULL) ? 'Y' : 'N';
+	buf[1] = '\n';
+	buf[2] = '\0';
+
+	return simple_read_from_buffer(ubuf, size, offp, buf, 2);
+}
+
+static ssize_t tool_link_write(struct file *filep, const char __user *ubuf,
+			       size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+	char buf[32];
+	size_t buf_size;
+	bool val;
+	int rc;
+
+	buf_size = min(size, (sizeof(buf) - 1));
+	if (copy_from_user(buf, ubuf, buf_size))
+		return -EFAULT;
+
+	buf[buf_size] = '\0';
+
+	rc = strtobool(buf, &val);
+	if (rc)
+		return rc;
+
+	if (val)
+		rc = ntb_link_enable(tc->ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
+	else
+		rc = ntb_link_disable(tc->ntb);
+
+	if (rc)
+		return rc;
+
+	return size;
+}
+
+static TOOL_FOPS_RDWR(tool_link_fops,
+		      tool_link_read,
+		      tool_link_write);
+
+static ssize_t tool_link_event_write(struct file *filep,
+				     const char __user *ubuf,
+				     size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+	char buf[32];
+	size_t buf_size;
+	bool val;
+	int rc;
+
+	buf_size = min(size, (sizeof(buf) - 1));
+	if (copy_from_user(buf, ubuf, buf_size))
+		return -EFAULT;
+
+	buf[buf_size] = '\0';
+
+	rc = strtobool(buf, &val);
+	if (rc)
+		return rc;
+
+	if (wait_event_interruptible(tc->link_wq,
+		ntb_link_is_up(tc->ntb, NULL, NULL) == val))
+		return -ERESTART;
+
+	return size;
+}
+
+static TOOL_FOPS_RDWR(tool_link_event_fops,
+		      NULL,
+		      tool_link_event_write);
 
 static ssize_t tool_mw_read(struct file *filep, char __user *ubuf,
 			    size_t size, loff_t *offp)
@@ -803,6 +888,12 @@ static void tool_setup_dbgfs(struct tool_ctx *tc)
 	debugfs_create_file("peer_spad", S_IRUSR | S_IWUSR, tc->dbgfs,
 			    tc, &tool_peer_spad_fops);
 
+	debugfs_create_file("link", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_link_fops);
+
+	debugfs_create_file("link_event", S_IWUSR, tc->dbgfs,
+			    tc, &tool_link_event_fops);
+
 	for (i = 0; i < tc->mw_count; i++) {
 		char buf[30];
 
@@ -835,6 +926,7 @@ static int tool_probe(struct ntb_client *self, struct ntb_dev *ntb)
 	}
 
 	tc->ntb = ntb;
+	init_waitqueue_head(&tc->link_wq);
 
 	tc->mw_count = min(ntb_mw_count(tc->ntb), MAX_MWS);
 	for (i = 0; i < tc->mw_count; i++) {