linux-kernel - [PATCH v2 4/7] net: phy: add helper for mapping RGMII link speed to clock rate

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Message-ID:
 <AM9PR04MB85062E3A66BA92EF8D996513E2832@AM9PR04MB8506.eurprd04.prod.outlook.com>
Date: Sun, 18 Aug 2024 21:50:46 +0000
From: "Jan Petrous (OSS)" <jan.petrous@....nxp.com>
To: "Jan Petrous (OSS)" <jan.petrous@....nxp.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>, Alexandre Torgue <alexandre.torgue@...s.st.com>, Jose
 Abreu <joabreu@...opsys.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Vinod Koul <vkoul@...nel.org>, Andrew Lunn <andrew@...n.ch>, Heiner Kallweit
	<hkallweit1@...il.com>, Russell King <linux@...linux.org.uk>, Richard Cochran
	<richardcochran@...il.com>, Giuseppe Cavallaro <peppe.cavallaro@...com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-stm32@...md-mailman.stormreply.com"
	<linux-stm32@...md-mailman.stormreply.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-arm-msm@...r.kernel.org"
	<linux-arm-msm@...r.kernel.org>, dl-S32 <S32@....com>
Subject: [PATCH v2 4/7] net: phy: add helper for mapping RGMII link speed to
 clock rate

The helper rgmii_clock() implemented Russel's hint during stmmac
glue driver review:

---
We seem to have multiple cases of very similar logic in lots of stmmac
platform drivers, and I think it's about time we said no more to this.
So, what I think we should do is as follows:

add the following helper - either in stmmac, or more generically
(phylib? - in which case its name will need changing.)

static long stmmac_get_rgmii_clock(int speed)
{
	switch (speed) {
	case SPEED_10:
		return 2500000;

	case SPEED_100:
		return 25000000;

	case SPEED_1000:
		return 125000000;

	default:
		return -ENVAL;
	}
}

Then, this can become:

	long tx_clk_rate;

	...

	tx_clk_rate = stmmac_get_rgmii_clock(speed);
	if (tx_clk_rate < 0) {
		dev_err(gmac->dev, "Unsupported/Invalid speed: %d\n", speed);
		return;
	}

	ret = clk_set_rate(gmac->tx_clk, tx_clk_rate);
---

Signed-off-by: Jan Petrous (OSS) <jan.petrous@....nxp.com>
---
 include/linux/phy.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 6b7d40d49129..bb797364d91c 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -298,6 +298,27 @@ static inline const char *phy_modes(phy_interface_t interface)
 	}
 }
 
+/**
+ * rgmi_clock - map link speed to the clock rate
+ * @speed: link speed value
+ *
+ * Description: maps RGMII supported link speeds
+ * into the clock rates.
+ */
+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
 
-- 
2.46.0