netdev - [PATCH RFC net-next v6 04/15] net: phy: Add helper for mapping RGMII link speed to clock rate

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Message-Id: <20241124-upstream_s32cc_gmac-v6-4-dc5718ccf001@oss.nxp.com>
Date: Sun, 24 Nov 2024 23:42:35 +0100
From: Jan Petrous via B4 Relay <devnull+jan.petrous.oss.nxp.com@...nel.org>
To: Maxime Coquelin <mcoquelin.stm32@...il.com>, 
 Alexandre Torgue <alexandre.torgue@...s.st.com>, 
 Jose Abreu <joabreu@...opsys.com>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Vinod Koul <vkoul@...nel.org>, 
 Richard Cochran <richardcochran@...il.com>, Andrew Lunn <andrew@...n.ch>, 
 Heiner Kallweit <hkallweit1@...il.com>, 
 Russell King <linux@...linux.org.uk>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, Emil Renner Berthing <kernel@...il.dk>, 
 Minda Chen <minda.chen@...rfivetech.com>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Iyappan Subramanian <iyappan@...amperecomputing.com>, 
 Keyur Chudgar <keyur@...amperecomputing.com>, 
 Quan Nguyen <quan@...amperecomputing.com>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Giuseppe Cavallaro <peppe.cavallaro@...com>, 
 Andrew Lunn <andrew+netdev@...n.ch>
Cc: linux-stm32@...md-mailman.stormreply.com, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 netdev@...r.kernel.org, linux-arm-msm@...r.kernel.org, imx@...ts.linux.dev, 
 devicetree@...r.kernel.org, NXP S32 Linux Team <s32@....com>, 
 "Jan Petrous (OSS)" <jan.petrous@....nxp.com>, 
 "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Subject: [PATCH RFC net-next v6 04/15] net: phy: Add helper for mapping
 RGMII link speed to clock rate

From: "Jan Petrous (OSS)" <jan.petrous@....nxp.com>

The RGMII interface supports three data rates: 10/100 Mbps
and 1 Gbps. These speeds correspond to clock frequencies
of 2.5/25 MHz and 125 MHz, respectively.

Many Ethernet drivers, including glues in stmmac, follow
a similar pattern of converting RGMII speed to clock frequency.

To simplify code, define the helper rgmii_clock(speed)
to convert connection speed to clock frequency.

Suggested-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Reviewed-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
Signed-off-by: Jan Petrous (OSS) <jan.petrous@....nxp.com>
---
 include/linux/phy.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 77c6d6451638..9d0717ccd5c0 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -298,6 +298,29 @@ static inline const char *phy_modes(phy_interface_t interface)
 	}
 }

+/**
+ * rgmii_clock - map link speed to the clock rate
+ * @speed: link speed value
+ *
+ * Description: maps RGMII supported link speeds
+ * into the clock rates.
+ *
+ * Returns: clock rate or negative errno
+ */
+static inline long rgmii_clock(int speed)
+{
+	switch (speed) {
+	case SPEED_10:
+		return 2500000;
+	case SPEED_100:
+		return 25000000;
+	case SPEED_1000:
+		return 125000000;
+	default:
+		return -EINVAL;
+	}
+}
+
 #define PHY_INIT_TIMEOUT	100000
 #define PHY_FORCE_TIMEOUT	10

-- 
2.47.0