[PATCH net-next 1/2] net: dsa: realtek: support reset controller

[Luiz Angelo Daros de Luca <luizluca@gmail.com>]

The 'reset-gpios' will not work when the switch reset is controlled by a
reset controller.

Although the reset is optional and the driver performs a soft reset
during setup, if the initial reset state was asserted, the driver will
not detect it.

This is an example of how to use the reset controller:

        switch {
                compatible = "realtek,rtl8366rb";

                resets = <&rst 8>;
                reset-names = "switch";

		...
	}

The reset controller will take precedence over the reset GPIO.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
---
 drivers/net/dsa/realtek/realtek-mdio.c | 36 +++++++++++++++++++++-----
 drivers/net/dsa/realtek/realtek-smi.c  | 34 +++++++++++++++++++-----
 drivers/net/dsa/realtek/realtek.h      |  6 +++++
 3 files changed, 63 insertions(+), 13 deletions(-)

diff --git a/drivers/net/dsa/realtek/realtek-mdio.c b/drivers/net/dsa/realtek/realtek-mdio.c
index 292e6d087e8b..600124c58c00 100644
--- a/drivers/net/dsa/realtek/realtek-mdio.c
+++ b/drivers/net/dsa/realtek/realtek-mdio.c
@@ -140,6 +140,23 @@ static const struct regmap_config realtek_mdio_nolock_regmap_config = {
 	.disable_locking = true,
 };
 
+static int realtek_mdio_hwreset(struct realtek_priv *priv, bool active)
+{
+#ifdef CONFIG_RESET_CONTROLLER
+	if (priv->reset_ctl) {
+		if (active)
+			return reset_control_assert(priv->reset_ctl);
+		else
+			return reset_control_deassert(priv->reset_ctl);
+	}
+#endif
+
+	if (priv->reset)
+		gpiod_set_value(priv->reset, active);
+
+	return 0;
+}
+
 static int realtek_mdio_probe(struct mdio_device *mdiodev)
 {
 	struct realtek_priv *priv;
@@ -194,20 +211,26 @@ static int realtek_mdio_probe(struct mdio_device *mdiodev)
 
 	dev_set_drvdata(dev, priv);
 
-	/* TODO: if power is software controlled, set up any regulators here */
 	priv->leds_disabled = of_property_read_bool(np, "realtek,disable-leds");
 
+#ifdef CONFIG_RESET_CONTROLLER
+	priv->reset_ctl = devm_reset_control_get(dev, "switch");
+	if (IS_ERR(priv->reset_ctl)) {
+		dev_err(dev, "failed to get switch reset control\n");
+		return PTR_ERR(priv->reset_ctl);
+	}
+#endif
+
 	priv->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
 	if (IS_ERR(priv->reset)) {
 		dev_err(dev, "failed to get RESET GPIO\n");
 		return PTR_ERR(priv->reset);
 	}
-
-	if (priv->reset) {
-		gpiod_set_value(priv->reset, 1);
+	if (priv->reset_ctl || priv->reset) {
+		realtek_mdio_hwreset(priv, 1);
 		dev_dbg(dev, "asserted RESET\n");
 		msleep(REALTEK_HW_STOP_DELAY);
-		gpiod_set_value(priv->reset, 0);
+		realtek_mdio_hwreset(priv, 0);
 		msleep(REALTEK_HW_START_DELAY);
 		dev_dbg(dev, "deasserted RESET\n");
 	}
@@ -246,8 +269,7 @@ static void realtek_mdio_remove(struct mdio_device *mdiodev)
 	dsa_unregister_switch(priv->ds);
 
 	/* leave the device reset asserted */
-	if (priv->reset)
-		gpiod_set_value(priv->reset, 1);
+	realtek_mdio_hwreset(priv, 1);
 }
 
 static void realtek_mdio_shutdown(struct mdio_device *mdiodev)
diff --git a/drivers/net/dsa/realtek/realtek-smi.c b/drivers/net/dsa/realtek/realtek-smi.c
index bfd11591faf4..751159d71223 100644
--- a/drivers/net/dsa/realtek/realtek-smi.c
+++ b/drivers/net/dsa/realtek/realtek-smi.c
@@ -408,6 +408,23 @@ static int realtek_smi_setup_mdio(struct dsa_switch *ds)
 	return ret;
 }
 
+static int realtek_smi_hwreset(struct realtek_priv *priv, bool active)
+{
+#ifdef CONFIG_RESET_CONTROLLER
+	if (priv->reset_ctl) {
+		if (active)
+			return reset_control_assert(priv->reset_ctl);
+		else
+			return reset_control_deassert(priv->reset_ctl);
+	}
+#endif
+
+	if (priv->reset)
+		gpiod_set_value(priv->reset, active);
+
+	return 0;
+}
+
 static int realtek_smi_probe(struct platform_device *pdev)
 {
 	const struct realtek_variant *var;
@@ -457,18 +474,24 @@ static int realtek_smi_probe(struct platform_device *pdev)
 	dev_set_drvdata(dev, priv);
 	spin_lock_init(&priv->lock);
 
-	/* TODO: if power is software controlled, set up any regulators here */
+#ifdef CONFIG_RESET_CONTROLLER
+	priv->reset_ctl = devm_reset_control_get(dev, "switch");
+	if (IS_ERR(priv->reset_ctl)) {
+		dev_err(dev, "failed to get switch reset control\n");
+		return PTR_ERR(priv->reset_ctl);
+	}
+#endif
 
 	priv->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
 	if (IS_ERR(priv->reset)) {
 		dev_err(dev, "failed to get RESET GPIO\n");
 		return PTR_ERR(priv->reset);
 	}
-	if (priv->reset) {
-		gpiod_set_value(priv->reset, 1);
+	if (priv->reset_ctl || priv->reset) {
+		realtek_smi_hwreset(priv, 1);
 		dev_dbg(dev, "asserted RESET\n");
 		msleep(REALTEK_HW_STOP_DELAY);
-		gpiod_set_value(priv->reset, 0);
+		realtek_smi_hwreset(priv, 0);
 		msleep(REALTEK_HW_START_DELAY);
 		dev_dbg(dev, "deasserted RESET\n");
 	}
@@ -518,8 +541,7 @@ static void realtek_smi_remove(struct platform_device *pdev)
 		of_node_put(priv->slave_mii_bus->dev.of_node);
 
 	/* leave the device reset asserted */
-	if (priv->reset)
-		gpiod_set_value(priv->reset, 1);
+	realtek_smi_hwreset(priv, 1);
 }
 
 static void realtek_smi_shutdown(struct platform_device *pdev)
diff --git a/drivers/net/dsa/realtek/realtek.h b/drivers/net/dsa/realtek/realtek.h
index 4fa7c6ba874a..ad61e5c13f96 100644
--- a/drivers/net/dsa/realtek/realtek.h
+++ b/drivers/net/dsa/realtek/realtek.h
@@ -12,6 +12,9 @@
 #include <linux/platform_device.h>
 #include <linux/gpio/consumer.h>
 #include <net/dsa.h>
+#ifdef CONFIG_RESET_CONTROLLER
+#include <linux/reset.h>
+#endif
 
 #define REALTEK_HW_STOP_DELAY		25	/* msecs */
 #define REALTEK_HW_START_DELAY		100	/* msecs */
@@ -48,6 +51,9 @@ struct rtl8366_vlan_4k {
 
 struct realtek_priv {
 	struct device		*dev;
+#ifdef CONFIG_RESET_CONTROLLER
+	struct reset_control    *reset_ctl;
+#endif
 	struct gpio_desc	*reset;
 	struct gpio_desc	*mdc;
 	struct gpio_desc	*mdio;
-- 
2.42.0