[PATCH 5/9] net: mdio: ipq4019: support MDIO clock frequency divider

[Luo Jie <quic_luoj@xxxxxxxxxxx>]

The MDIO clock frequency can be divided according to the
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@xxxxxxxxxxx>
---
 drivers/net/mdio/mdio-ipq4019.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/mdio/mdio-ipq4019.c b/drivers/net/mdio/mdio-ipq4019.c
index ca9cda98d1f8..44a8a866f8ee 100644
--- a/drivers/net/mdio/mdio-ipq4019.c
+++ b/drivers/net/mdio/mdio-ipq4019.c
@@ -30,6 +30,9 @@
 /* 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
 
@@ -65,6 +68,7 @@ struct ipq4019_mdio_data {
 	void __iomem *eth_ldo_rdy[ETH_LDO_RDY_CNT];
 	struct clk *clk[MDIO_CLK_CNT];
 	struct gpio_descs *reset_gpios;
+	int clk_div;
 };
 
 const char *const mdio_clk_name[] = {
@@ -98,6 +102,7 @@ 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);
 
@@ -139,6 +144,7 @@ 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);
 
@@ -171,6 +177,7 @@ 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);
 
@@ -214,6 +221,7 @@ 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);
 
@@ -431,6 +439,9 @@ static int ipq4019_mdio_probe(struct platform_device *pdev)
 		return dev_err_probe(&pdev->dev, PTR_ERR(priv->reset_gpios),
 				     "mii_bus %s couldn't get reset GPIO\n", bus->id);
 
+	/* MDIO default frequency is 6.25MHz */
+	priv->clk_div = 0xf;
+
 	bus->name = "ipq4019_mdio";
 	bus->read = ipq4019_mdio_read_c22;
 	bus->write = ipq4019_mdio_write_c22;
-- 
2.42.0