net: phy: adin: add support for clock output

The ADIN1300 supports generating certain clocks on its GP_CLK pin, as
well as providing the reference clock on CLK25_REF.

Add support for selecting the clock via device-tree properties.

Technically the phy also supports a recovered 125MHz clock for
synchronous ethernet. SyncE should be configured dynamically at
runtime, however Linux does not currently have a toggle for this,
so support is explicitly omitted.
Co-developed-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Signed-off-by: Josua Mayer<josua@solid-run.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/adin.c

@@ -99,6 +99,15 @@
 #define ADIN1300_GE_SOFT_RESET_REG		0xff0c
 #define   ADIN1300_GE_SOFT_RESET		BIT(0)
 
+#define ADIN1300_GE_CLK_CFG_REG			0xff1f
+#define   ADIN1300_GE_CLK_CFG_MASK		GENMASK(5, 0)
+#define   ADIN1300_GE_CLK_CFG_RCVR_125		BIT(5)
+#define   ADIN1300_GE_CLK_CFG_FREE_125		BIT(4)
+#define   ADIN1300_GE_CLK_CFG_REF_EN		BIT(3)
+#define   ADIN1300_GE_CLK_CFG_HRT_RCVR		BIT(2)
+#define   ADIN1300_GE_CLK_CFG_HRT_FREE		BIT(1)
+#define   ADIN1300_GE_CLK_CFG_25		BIT(0)
+
 #define ADIN1300_GE_RGMII_CFG_REG		0xff23
 #define   ADIN1300_GE_RGMII_RX_MSK		GENMASK(8, 6)
 #define   ADIN1300_GE_RGMII_RX_SEL(x)		\
@@ -433,6 +442,33 @@ static int adin_set_tunable(struct phy_device *phydev,
 	}
 }
 
+static int adin_config_clk_out(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	const char *val = NULL;
+	u8 sel = 0;
+
+	device_property_read_string(dev, "adi,phy-output-clock", &val);
+	if (!val) {
+		/* property not present, do not enable GP_CLK pin */
+	} else if (strcmp(val, "25mhz-reference") == 0) {
+		sel |= ADIN1300_GE_CLK_CFG_25;
+	} else if (strcmp(val, "125mhz-free-running") == 0) {
+		sel |= ADIN1300_GE_CLK_CFG_FREE_125;
+	} else if (strcmp(val, "adaptive-free-running") == 0) {
+		sel |= ADIN1300_GE_CLK_CFG_HRT_FREE;
+	} else {
+		phydev_err(phydev, "invalid adi,phy-output-clock\n");
+		return -EINVAL;
+	}
+
+	if (device_property_read_bool(dev, "adi,phy-output-reference-clock"))
+		sel |= ADIN1300_GE_CLK_CFG_REF_EN;
+
+	return phy_modify_mmd(phydev, MDIO_MMD_VEND1, ADIN1300_GE_CLK_CFG_REG,
+			      ADIN1300_GE_CLK_CFG_MASK, sel);
+}
+
 static int adin_config_init(struct phy_device *phydev)
 {
 	int rc;
@@ -455,6 +491,10 @@ static int adin_config_init(struct phy_device *phydev)
 	if (rc < 0)
 		return rc;
 
+	rc = adin_config_clk_out(phydev);
+	if (rc < 0)
+		return rc;
+
 	phydev_dbg(phydev, "PHY is using mode '%s'\n",
 		   phy_modes(phydev->interface));