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

Luo Jie
2023-12-12T11:52:39Z

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@quicinc.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