dsa: mv88x6xxx: Add debugfs interface for statistics

Allow the contents of the statistics counters to be shown in debugfs.
This is particularly useful for the cpu and dsa ports, which cannot be
seen using ethtools -S.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx.c

@@ -1730,6 +1730,62 @@ static const struct file_operations mv88e6xxx_atu_fops = {
 	.owner  = THIS_MODULE,
 };
 
+static void mv88e6xxx_stats_show_header(struct seq_file *s,
+					struct mv88e6xxx_priv_state *ps)
+{
+	int port;
+
+	seq_puts(s, "      Statistic       ");
+	for (port = 0 ; port < ps->num_ports; port++)
+		seq_printf(s, "Port %2d  ", port);
+	seq_puts(s, "\n");
+}
+
+static int mv88e6xxx_stats_show(struct seq_file *s, void *p)
+{
+	struct dsa_switch *ds = s->private;
+	struct mv88e6xxx_priv_state *ps = ds_to_priv(ds);
+	struct mv88e6xxx_hw_stat *stats = mv88e6xxx_hw_stats;
+	int port, stat, max_stats;
+	uint64_t value;
+
+	if (have_sw_in_discards(ds))
+		max_stats = ARRAY_SIZE(mv88e6xxx_hw_stats);
+	else
+		max_stats = ARRAY_SIZE(mv88e6xxx_hw_stats) - 3;
+
+	mv88e6xxx_stats_show_header(s, ps);
+
+	mutex_lock(&ps->smi_mutex);
+
+	for (stat = 0; stat < max_stats; stat++) {
+		seq_printf(s, "%19s: ", stats[stat].string);
+		for (port = 0 ; port < ps->num_ports; port++) {
+			_mv88e6xxx_stats_snapshot(ds, port);
+			value = _mv88e6xxx_get_ethtool_stat(ds, stat, stats,
+							    port);
+			seq_printf(s, "%8llu ", value);
+		}
+		seq_puts(s, "\n");
+	}
+	mutex_unlock(&ps->smi_mutex);
+
+	return 0;
+}
+
+static int mv88e6xxx_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mv88e6xxx_stats_show, inode->i_private);
+}
+
+static const struct file_operations mv88e6xxx_stats_fops = {
+	.open   = mv88e6xxx_stats_open,
+	.read   = seq_read,
+	.llseek = no_llseek,
+	.release = single_release,
+	.owner  = THIS_MODULE,
+};
+
 int mv88e6xxx_setup_common(struct dsa_switch *ds)
 {
 	struct mv88e6xxx_priv_state *ps = ds_to_priv(ds);
@@ -1753,6 +1809,9 @@ int mv88e6xxx_setup_common(struct dsa_switch *ds)
 	debugfs_create_file("atu", S_IRUGO, ps->dbgfs, ds,
 			    &mv88e6xxx_atu_fops);
 
+	debugfs_create_file("stats", S_IRUGO, ps->dbgfs, ds,
+			    &mv88e6xxx_stats_fops);
+
 	return 0;
 }