netdev - [PATCH v2 4/5] net: mdio: ipq4019: support MDIO clock frequency divider

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Date: Tue, 12 Dec 2023 19:51:49 +0800
From: Luo Jie <quic_luoj@...cinc.com>
To: <agross@...nel.org>, <andersson@...nel.org>, <konrad.dybcio@...aro.org>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <andrew@...n.ch>, <hkallweit1@...il.com>, <linux@...linux.org.uk>,
        <robert.marko@...tura.hr>
CC: <linux-arm-msm@...r.kernel.org>, <netdev@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_srichara@...cinc.com>
Subject: [PATCH v2 4/5] net: mdio: ipq4019: support MDIO clock frequency divider

The MDIO clock frequency can be divided according to the
MDIO control register value.

The MDIO system clock is fixed to 100MHZ, the working
frequency is 100MHZ/(divider + 1), the divider value
is from the bit[7:0] of control register 0x40.

Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
---
 drivers/net/mdio/mdio-ipq4019.c | 45 +++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/net/mdio/mdio-ipq4019.c b/drivers/net/mdio/mdio-ipq4019.c
index 8d3c6bae379f..2c724d3cd513 100644
--- a/drivers/net/mdio/mdio-ipq4019.c
+++ b/drivers/net/mdio/mdio-ipq4019.c
@@ -29,6 +29,9 @@
 /* 0 = Clause 22, 1 = Clause 45 */
 #define MDIO_MODE_C45				BIT(8)
 
+/* MDC frequency is SYS_CLK/(MDIO_CLK_DIV + 1), SYS_CLK is 100MHz */
+#define MDIO_CLK_DIV_MASK			GENMASK(7, 0)
+
 #define IPQ4019_MDIO_TIMEOUT	10000
 #define IPQ4019_MDIO_SLEEP		10
 
@@ -77,6 +80,7 @@ struct ipq4019_mdio_data {
 	void __iomem *cmn_membase;
 	void __iomem *eth_ldo_rdy[ETH_LDO_RDY_CNT];
 	struct clk *clk[MDIO_CLK_CNT];
+	int clk_div;
 };
 
 static const char *const mdio_clk_name[] = {
@@ -110,6 +114,7 @@ static int ipq4019_mdio_read_c45(struct mii_bus *bus, int mii_id, int mmd,
 	data = readl(priv->membase + MDIO_MODE_REG);
 
 	data |= MDIO_MODE_C45;
+	data |= FIELD_PREP(MDIO_CLK_DIV_MASK, priv->clk_div);
 
 	writel(data, priv->membase + MDIO_MODE_REG);
 
@@ -151,6 +156,7 @@ static int ipq4019_mdio_read_c22(struct mii_bus *bus, int mii_id, int regnum)
 	data = readl(priv->membase + MDIO_MODE_REG);
 
 	data &= ~MDIO_MODE_C45;
+	data |= FIELD_PREP(MDIO_CLK_DIV_MASK, priv->clk_div);
 
 	writel(data, priv->membase + MDIO_MODE_REG);
 
@@ -183,6 +189,7 @@ static int ipq4019_mdio_write_c45(struct mii_bus *bus, int mii_id, int mmd,
 	data = readl(priv->membase + MDIO_MODE_REG);
 
 	data |= MDIO_MODE_C45;
+	data |= FIELD_PREP(MDIO_CLK_DIV_MASK, priv->clk_div);
 
 	writel(data, priv->membase + MDIO_MODE_REG);
 
@@ -226,6 +233,7 @@ static int ipq4019_mdio_write_c22(struct mii_bus *bus, int mii_id, int regnum,
 	data = readl(priv->membase + MDIO_MODE_REG);
 
 	data &= ~MDIO_MODE_C45;
+	data |= FIELD_PREP(MDIO_CLK_DIV_MASK, priv->clk_div);
 
 	writel(data, priv->membase + MDIO_MODE_REG);
 
@@ -397,6 +405,39 @@ static int ipq_mdio_reset(struct mii_bus *bus)
 	return ret;
 }
 
+static int ipq_mdio_clk_set(struct platform_device *pdev, int *clk_div)
+{
+	int freq;
+
+	/* Keep the MDIO clock divider as the hardware default value 0xff if
+	 * the MDIO property "clock-frequency" is not specified.
+	 */
+	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency", &freq)) {
+		*clk_div = 0xff;
+		return 0;
+	}
+
+	/* MDC frequency is SYS_CLK/(MDIO_CLK_DIV + 1), SYS_CLK is fixed
+	 * to 100MHz, the MDIO_CLK_DIV can be only configured the valid
+	 * values, other values cause malfunction.
+	 */
+	switch (freq) {
+	case 12500000:
+	case 6250000:
+	case 3125000:
+	case 1562500:
+	case 781250:
+	case 390625:
+		*clk_div = DIV_ROUND_UP(IPQ_MDIO_CLK_RATE, freq) - 1;
+		break;
+	default:
+		dev_err(&pdev->dev, "Invalid clock frequency %dHZ\n", freq);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int ipq4019_mdio_probe(struct platform_device *pdev)
 {
 	struct ipq4019_mdio_data *priv;
@@ -459,6 +500,10 @@ static int ipq4019_mdio_probe(struct platform_device *pdev)
 			return PTR_ERR(priv->clk[index]);
 	}
 
+	ret = ipq_mdio_clk_set(pdev, &priv->clk_div);
+	if (ret)
+		return ret;
+
 	bus->name = "ipq4019_mdio";
 	bus->read = ipq4019_mdio_read_c22;
 	bus->write = ipq4019_mdio_write_c22;
-- 
2.42.0