linux-kernel - [PATCH net-next 05/11] net: dsa: rzn1-a5psw: Add support for optional reset control

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Message-ID: <20251121113553.2955854-6-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Fri, 21 Nov 2025 11:35:31 +0000
From: Prabhakar <prabhakar.csengg@...il.com>
To: Clément Léger <clement.leger@...tlin.com>,
	Andrew Lunn <andrew@...n.ch>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Simon Horman <horms@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Russell King <linux@...linux.org.uk>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>
Cc: linux-renesas-soc@...r.kernel.org,
	netdev@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Prabhakar <prabhakar.csengg@...il.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH net-next 05/11] net: dsa: rzn1-a5psw: Add support for optional reset control

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Add support for an optional reset control to the RZN1 A5PSW driver.
Obtain the reset line using
devm_reset_control_get_optional_exclusive_deasserted() during probe
to ensure that the Ethernet switch (ETHSW) block is properly released
from reset before initialization.

This change prepares the driver for use on Renesas RZ/T2H and RZ/N2H
SoCs, where the ETHSW IP block is connected to a dedicated reset line
that must be controlled by software.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
 drivers/net/dsa/rzn1_a5psw.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/dsa/rzn1_a5psw.c b/drivers/net/dsa/rzn1_a5psw.c
index 1635255f58e4..7b84585a5415 100644
--- a/drivers/net/dsa/rzn1_a5psw.c
+++ b/drivers/net/dsa/rzn1_a5psw.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_mdio.h>
+#include <linux/reset.h>
 #include <net/dsa.h>
 
 #include "rzn1_a5psw.h"
@@ -1205,6 +1206,7 @@ static int a5psw_pcs_get(struct a5psw *a5psw)
 static int a5psw_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct reset_control *reset;
 	struct device_node *mdio;
 	struct dsa_switch *ds;
 	struct a5psw *a5psw;
@@ -1241,6 +1243,12 @@ static int a5psw_probe(struct platform_device *pdev)
 		goto free_pcs;
 	}
 
+	reset = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
+	if (IS_ERR(reset)) {
+		ret = PTR_ERR(reset);
+		goto free_pcs;
+	}
+
 	mdio = of_get_available_child_by_name(dev->of_node, "mdio");
 	if (mdio) {
 		ret = a5psw_probe_mdio(a5psw, mdio);
-- 
2.52.0