[PATCH net-next] net: dsa: mt7530: Add debugfs support

[Lorenzo Bianconi <lorenzo@kernel.org>]

Introduce debugfs support for mt7530 dsa switch.
Add the capability to read or write device registers through debugfs:

$echo 0x7ffc > regidx
$cat regval
0x75300000

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/dsa/mt7530-mmio.c | 12 +++++++++-
 drivers/net/dsa/mt7530.c      | 41 +++++++++++++++++++++++++++++++++++
 drivers/net/dsa/mt7530.h      |  5 +++++
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mt7530-mmio.c b/drivers/net/dsa/mt7530-mmio.c
index b74a230a3f13..cedb046ea2a3 100644
--- a/drivers/net/dsa/mt7530-mmio.c
+++ b/drivers/net/dsa/mt7530-mmio.c
@@ -60,7 +60,17 @@ mt7988_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->regmap))
 		return PTR_ERR(priv->regmap);
 
-	return dsa_register_switch(priv->ds);
+	ret = dsa_register_switch(priv->ds);
+	if (ret)
+		return ret;
+
+	ret = mt7530_register_debugfs(priv);
+	if (ret) {
+		dsa_unregister_switch(priv->ds);
+		return ret;
+	}
+
+	return 0;
 }
 
 static void mt7988_remove(struct platform_device *pdev)
diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 598434d8d6e4..18cb42a771e8 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -3,6 +3,7 @@
  * Mediatek MT7530 DSA Switch driver
  * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com>
  */
+#include <linux/debugfs.h>
 #include <linux/etherdevice.h>
 #include <linux/if_bridge.h>
 #include <linux/iopoll.h>
@@ -271,6 +272,28 @@ mt7530_clear(struct mt7530_priv *priv, u32 reg, u32 val)
 	mt7530_rmw(priv, reg, val, 0);
 }
 
+static int
+mt7530_reg_set(void *data, u64 val)
+{
+	struct mt7530_priv *priv = data;
+
+	mt7530_write(priv, priv->debugfs_reg, val);
+
+	return 0;
+}
+
+static int
+mt7530_reg_get(void *data, u64 *val)
+{
+	struct mt7530_priv *priv = data;
+
+	*val = mt7530_read(priv, priv->debugfs_reg);
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops, mt7530_reg_get, mt7530_reg_set, "0x%08llx\n");
+
 static int
 mt7530_fdb_cmd(struct mt7530_priv *priv, enum mt7530_fdb_cmd cmd, u32 *rsp)
 {
@@ -3218,6 +3241,22 @@ const struct mt753x_info mt753x_table[] = {
 };
 EXPORT_SYMBOL_GPL(mt753x_table);
 
+int
+mt7530_register_debugfs(struct mt7530_priv *priv)
+{
+	priv->debugfs_dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
+	if (IS_ERR(priv->debugfs_dir))
+		return PTR_ERR(priv->debugfs_dir);
+
+	debugfs_create_u32("regidx", 0600, priv->debugfs_dir,
+			   &priv->debugfs_reg);
+	debugfs_create_file_unsafe("regval", 0600, priv->debugfs_dir, priv,
+				   &fops);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mt7530_register_debugfs);
+
 int
 mt7530_probe_common(struct mt7530_priv *priv)
 {
@@ -3252,6 +3291,8 @@ EXPORT_SYMBOL_GPL(mt7530_probe_common);
 void
 mt7530_remove_common(struct mt7530_priv *priv)
 {
+	debugfs_remove(priv->debugfs_dir);
+
 	if (priv->irq)
 		mt7530_free_irq(priv);
 
diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h
index 2ea4e24628c6..b7568c1c6d5e 100644
--- a/drivers/net/dsa/mt7530.h
+++ b/drivers/net/dsa/mt7530.h
@@ -798,6 +798,8 @@ struct mt753x_info {
  * @create_sgmii:	Pointer to function creating SGMII PCS instance(s)
  * @active_cpu_ports:	Holding the active CPU ports
  * @mdiodev:		The pointer to the MDIO device structure
+ * @debugfs_dir:	Debugfs entry point
+ * @debugfs_reg:	Selected register to read or write through debugfs
  */
 struct mt7530_priv {
 	struct device		*dev;
@@ -825,6 +827,8 @@ struct mt7530_priv {
 	int (*create_sgmii)(struct mt7530_priv *priv);
 	u8 active_cpu_ports;
 	struct mdio_device *mdiodev;
+	struct dentry *debugfs_dir;
+	u32 debugfs_reg;
 };
 
 struct mt7530_hw_vlan_entry {
@@ -861,6 +865,7 @@ static inline void INIT_MT7530_DUMMY_POLL(struct mt7530_dummy_poll *p,
 	p->reg = reg;
 }
 
+int mt7530_register_debugfs(struct mt7530_priv *priv);
 int mt7530_probe_common(struct mt7530_priv *priv);
 void mt7530_remove_common(struct mt7530_priv *priv);
 
-- 
2.45.1