netdev - [net-next,PATCH 3/3] net: phy: realtek: Add property to enable SSC

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251130005843.234656-3-marek.vasut@mailbox.org>
Date: Sun, 30 Nov 2025 01:58:34 +0100
From: Marek Vasut <marek.vasut@...lbox.org>
To: netdev@...r.kernel.org
Cc: Marek Vasut <marek.vasut@...lbox.org>,
	"David S. Miller" <davem@...emloft.net>,
	Aleksander Jan Bajkowski <olek2@...pl>,
	Andrew Lunn <andrew@...n.ch>,
	Conor Dooley <conor+dt@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Michael Klein <michael@...sekall.de>,
	Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Russell King <linux@...linux.org.uk>,
	Vladimir Oltean <vladimir.oltean@....com>,
	devicetree@...r.kernel.org
Subject: [net-next,PATCH 3/3] net: phy: realtek: Add property to enable SSC

Add support for spread spectrum clocking (SSC) on RTL8211F(D)(I)-CG,
RTL8211FS(I)(-VS)-CG, RTL8211FG(I)(-VS)-CG PHYs. The implementation
follows EMI improvement application note Rev. 1.2 for these PHYs.

The current implementation enables SSC for both RXC and SYSCLK clock
signals. Introduce new DT property 'realtek,ssc-enable' to enable the
SSC mode.

Signed-off-by: Marek Vasut <marek.vasut@...lbox.org>
---
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Aleksander Jan Bajkowski <olek2@...pl>
Cc: Andrew Lunn <andrew@...n.ch>
Cc: Conor Dooley <conor+dt@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Florian Fainelli <f.fainelli@...il.com>
Cc: Heiner Kallweit <hkallweit1@...il.com>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Krzysztof Kozlowski <krzk+dt@...nel.org>
Cc: Michael Klein <michael@...sekall.de>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: Rob Herring <robh@...nel.org>
Cc: Russell King <linux@...linux.org.uk>
Cc: Vladimir Oltean <vladimir.oltean@....com>
Cc: devicetree@...r.kernel.org
Cc: netdev@...r.kernel.org
---
 drivers/net/phy/realtek/realtek_main.c | 47 ++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/net/phy/realtek/realtek_main.c b/drivers/net/phy/realtek/realtek_main.c
index 67ecf3d4af2b1..b1b48936d6422 100644
--- a/drivers/net/phy/realtek/realtek_main.c
+++ b/drivers/net/phy/realtek/realtek_main.c
@@ -74,11 +74,17 @@
 
 #define RTL8211F_PHYCR2				0x19
 #define RTL8211F_CLKOUT_EN			BIT(0)
+#define RTL8211F_SYSCLK_SSC_EN			BIT(3)
 #define RTL8211F_PHYCR2_PHY_EEE_ENABLE		BIT(5)
 
 #define RTL8211F_INSR_PAGE			0xa43
 #define RTL8211F_INSR				0x1d
 
+/* RTL8211F SSC settings */
+#define RTL8211F_SSC_PAGE			0xc44
+#define RTL8211F_SSC_RXC			0x13
+#define RTL8211F_SSC_SYSCLK			0x17
+
 /* RTL8211F LED configuration */
 #define RTL8211F_LEDCR_PAGE			0xd04
 #define RTL8211F_LEDCR				0x10
@@ -203,6 +209,7 @@ MODULE_LICENSE("GPL");
 struct rtl821x_priv {
 	bool enable_aldps;
 	bool disable_clk_out;
+	bool enable_ssc;
 	struct clk *clk;
 	/* rtl8211f */
 	u16 iner;
@@ -266,6 +273,8 @@ static int rtl821x_probe(struct phy_device *phydev)
 						   "realtek,aldps-enable");
 	priv->disable_clk_out = of_property_read_bool(dev->of_node,
 						      "realtek,clkout-disable");
+	priv->enable_ssc = of_property_read_bool(dev->of_node,
+						 "realtek,ssc-enable");
 
 	phydev->priv = priv;
 
@@ -700,6 +709,37 @@ static int rtl8211f_config_phy_eee(struct phy_device *phydev)
 				RTL8211F_PHYCR2_PHY_EEE_ENABLE, 0);
 }
 
+static int rtl8211f_config_ssc(struct phy_device *phydev)
+{
+	struct rtl821x_priv *priv = phydev->priv;
+	struct device *dev = &phydev->mdio.dev;
+	int ret;
+
+	/* The value is preserved if the device tree property is absent */
+	if (!priv->enable_ssc)
+		return 0;
+
+	/* RTL8211FVD has no PHYCR2 register */
+	if (phydev->drv->phy_id == RTL_8211FVD_PHYID)
+		return 0;
+
+	ret = phy_write_paged(phydev, RTL8211F_SSC_PAGE, RTL8211F_SSC_RXC, 0x5f00);
+	if (ret < 0) {
+		dev_err(dev, "RXC SCC configuration failed: %pe\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	ret = phy_write_paged(phydev, RTL8211F_SSC_PAGE, RTL8211F_SSC_SYSCLK, 0x4f00);
+	if (ret < 0) {
+		dev_err(dev, "SYSCLK SCC configuration failed: %pe\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	/* Enable SSC */
+	return phy_modify_paged(phydev, RTL8211F_PHYCR_PAGE, RTL8211F_PHYCR2,
+				RTL8211F_SYSCLK_SSC_EN, RTL8211F_SYSCLK_SSC_EN);
+}
+
 static int rtl8211f_config_init(struct phy_device *phydev)
 {
 	struct device *dev = &phydev->mdio.dev;
@@ -723,6 +763,13 @@ static int rtl8211f_config_init(struct phy_device *phydev)
 		return ret;
 	}
 
+	ret = rtl8211f_config_ssc(phydev);
+	if (ret) {
+		dev_err(dev, "SSC mode configuration failed: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
 	return rtl8211f_config_phy_eee(phydev);
 }
 
-- 
2.51.0