linux-kernel - [PATCH net-next 1/3] net: phy: add phy_reset_after_power

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Date:   Tue, 14 Dec 2021 13:16:36 +0100
From:   Philippe Schenker <philippe.schenker@...adex.com>
To:     netdev@...r.kernel.org, Joakim Zhang <qiangqing.zhang@....com>,
        "David S . Miller" <davem@...emloft.net>,
        Russell King <linux@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Fabio Estevam <festevam@...il.com>,
        Fugang Duan <fugang.duan@....com>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 1/3] net: phy: add phy_reset_after_power_on() function

Some PHY requires a reset after being powered on (e.g. KSZ9131), add a
new function and related PHY_RST_AFTER_POWER_ON phy flag to be called
after the PHY regulator is enabled.

Signed-off-by: Philippe Schenker <philippe.schenker@...adex.com>
---

 drivers/net/phy/phy_device.c | 24 ++++++++++++++++++++++++
 include/linux/phy.h          |  2 ++
 2 files changed, 26 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 74d8e1dc125f..bad836a7ee01 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1878,6 +1878,30 @@ int phy_reset_after_clk_enable(struct phy_device *phydev)
 }
 EXPORT_SYMBOL(phy_reset_after_clk_enable);
 
+/**
+ * phy_reset_after_power_on - perform a PHY reset if needed
+ * @phydev: target phy_device struct
+ *
+ * Description: Some PHYs or hardware design, need a reset after power was
+ *   enabled and rely on that software reset. This function evaluates the flags
+ *   and perform the reset if it's needed.
+ *   Returns < 0 on error, 0 if the phy wasn't reset and 1 if the phy was reset.
+ */
+int phy_reset_after_power_on(struct phy_device *phydev)
+{
+	if (!phydev || !phydev->drv)
+		return -ENODEV;
+
+	if (phydev->drv->flags & PHY_RST_AFTER_POWER_ON) {
+		phy_device_reset(phydev, 1);
+		phy_device_reset(phydev, 0);
+		return 1;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(phy_reset_after_power_on);
+
 /* Generic PHY support and helper functions */
 
 /**
diff --git a/include/linux/phy.h b/include/linux/phy.h
index cbf03a5f9cf5..0d88cdc97dbd 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -80,6 +80,7 @@ extern const int phy_10gbit_features_array[1];
 #define PHY_IS_INTERNAL		0x00000001
 #define PHY_RST_AFTER_CLK_EN	0x00000002
 #define PHY_POLL_CABLE_TEST	0x00000004
+#define PHY_RST_AFTER_POWER_ON	0x00000008
 #define MDIO_DEVICE_IS_PHY	0x80000000
 
 /**
@@ -1499,6 +1500,7 @@ int phy_speed_up(struct phy_device *phydev);
 
 int phy_restart_aneg(struct phy_device *phydev);
 int phy_reset_after_clk_enable(struct phy_device *phydev);
+int phy_reset_after_power_on(struct phy_device *phydev);
 
 #if IS_ENABLED(CONFIG_PHYLIB)
 int phy_start_cable_test(struct phy_device *phydev,
-- 
2.34.1