[RFC net-next 5/5] 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.

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-common.c | 53 +++++++++++++++++++++---
 drivers/net/dsa/realtek/realtek-common.h |  3 ++
 drivers/net/dsa/realtek/realtek.h        |  2 +
 3 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/realtek/realtek-common.c b/drivers/net/dsa/realtek/realtek-common.c
index e383db21c776..1450e5c206c3 100644
--- a/drivers/net/dsa/realtek/realtek-common.c
+++ b/drivers/net/dsa/realtek/realtek-common.c
@@ -163,17 +163,25 @@ struct realtek_priv *realtek_common_probe(struct device *dev,
 	priv->leds_disabled = of_property_read_bool(np, "realtek,disable-leds");
 
 	/* TODO: if power is software controlled, set up any regulators here */
+	priv->reset_ctl = devm_reset_control_get_optional(dev, NULL);
+	if (IS_ERR(priv->reset_ctl)) {
+		ret = PTR_ERR(priv->reset_ctl);
+		dev_err_probe(dev, ret, "failed to get reset control\n");
+		goto err_variant_put;
+	}
+
 	priv->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
 	if (IS_ERR(priv->reset)) {
 		ret = PTR_ERR(priv->reset);
 		dev_err(dev, "failed to get RESET GPIO\n");
 		goto err_variant_put;
 	}
-	if (priv->reset) {
-		gpiod_set_value(priv->reset, 1);
+
+	if (priv->reset_ctl || priv->reset) {
+		realtek_reset_assert(priv);
 		dev_dbg(dev, "asserted RESET\n");
 		msleep(REALTEK_HW_STOP_DELAY);
-		gpiod_set_value(priv->reset, 0);
+		realtek_reset_deassert(priv);
 		msleep(REALTEK_HW_START_DELAY);
 		dev_dbg(dev, "deasserted RESET\n");
 	}
@@ -208,11 +216,46 @@ void realtek_common_remove(struct realtek_priv *priv)
 	realtek_variant_put(priv->variant);
 
 	/* leave the device reset asserted */
-	if (priv->reset)
-		gpiod_set_value(priv->reset, 1);
+	realtek_reset_assert(priv);
 }
 EXPORT_SYMBOL(realtek_common_remove);
 
+void realtek_reset_assert(struct realtek_priv *priv)
+{
+	int ret;
+
+	if (priv->reset_ctl) {
+		ret = reset_control_assert(priv->reset_ctl);
+		if (!ret)
+			return;
+
+		dev_warn(priv->dev,
+			 "Failed to assert the switch reset control: %pe\n",
+			 ERR_PTR(ret));
+	}
+
+	if (priv->reset)
+		gpiod_set_value(priv->reset, true);
+}
+
+void realtek_reset_deassert(struct realtek_priv *priv)
+{
+	int ret;
+
+	if (priv->reset_ctl) {
+		ret = reset_control_deassert(priv->reset_ctl);
+		if (!ret)
+			return;
+
+		dev_warn(priv->dev,
+			 "Failed to deassert the switch reset control: %pe\n",
+			 ERR_PTR(ret));
+	}
+
+	if (priv->reset)
+		gpiod_set_value(priv->reset, false);
+}
+
 const struct of_device_id realtek_common_of_match[] = {
 #if IS_ENABLED(CONFIG_NET_DSA_REALTEK_RTL8366RB)
 	{ .compatible = "realtek,rtl8366rb", .data = REALTEK_RTL8366RB_MODNAME, },
diff --git a/drivers/net/dsa/realtek/realtek-common.h b/drivers/net/dsa/realtek/realtek-common.h
index 089fda2d4fa9..603b4f9891d3 100644
--- a/drivers/net/dsa/realtek/realtek-common.h
+++ b/drivers/net/dsa/realtek/realtek-common.h
@@ -16,4 +16,7 @@ const struct realtek_variant *realtek_variant_get(
 		const struct of_device_id *match);
 void realtek_variant_put(const struct realtek_variant *var);
 
+void realtek_reset_assert(struct realtek_priv *priv);
+void realtek_reset_deassert(struct realtek_priv *priv);
+
 #endif
diff --git a/drivers/net/dsa/realtek/realtek.h b/drivers/net/dsa/realtek/realtek.h
index f9bd6678e3bd..86f33327155b 100644
--- a/drivers/net/dsa/realtek/realtek.h
+++ b/drivers/net/dsa/realtek/realtek.h
@@ -12,6 +12,7 @@
 #include <linux/platform_device.h>
 #include <linux/gpio/consumer.h>
 #include <net/dsa.h>
+#include <linux/reset.h>
 
 #define REALTEK_HW_STOP_DELAY		25	/* msecs */
 #define REALTEK_HW_START_DELAY		100	/* msecs */
@@ -80,6 +81,7 @@ struct rtl8366_vlan_4k {
 
 struct realtek_priv {
 	struct device		*dev;
+	struct reset_control    *reset_ctl;
 	struct gpio_desc	*reset;
 	struct gpio_desc	*mdc;
 	struct gpio_desc	*mdio;
-- 
2.42.1