[PATCH net-next v3] net: phy: motorcomm: enable the reference clock for YT8521 and YT8531

[PATCH net-next v3] net: phy: motorcomm: enable the reference clock for YT8521 and YT8531

[Jiaxing Hu]

These PHYs need a 25 MHz reference. On boards without a local crystal
it is fed from the SoC and described as a clock on the PHY node. Get and
enable it in probe, in both yt8521_probe and yt8531_probe, so the PHY is
clocked before its registers are accessed. The clock is optional, so
crystal-clocked boards are unaffected.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Gavin Gao <attinagaoxu@gmail.com>
Signed-off-by: Jiaxing Hu <gahing@gahingwoo.com>
---

Changes in v3:
- Open-code the clock enable in yt8521_probe and yt8531_probe instead of
  a helper; the block is short and self-explanatory inline (Alexey
  Charkov). No functional change, so Andrew's Reviewed-by and Gavin's
  Tested-by are carried over.

Changes in v2:
- Also enable the reference clock for the YT8521, not only the YT8531.

v1: https://lore.kernel.org/all/20260719034555.3623003-1-gahing@gahingwoo.com/
v2: https://lore.kernel.org/all/20260727205602.1188008-1-gahing@gahingwoo.com/

The DTS that consumes the clock (rk3576-armsom-cm5) goes to the rockchip
tree separately; the clock is optional so this patch stands alone. Tested
on an ArmSoM CM5-IO (YT8531) and a PicoCOM RK3576 board (YT8521).
 drivers/net/phy/motorcomm.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
index 708491bc1..bb2e9f4f5 100644
--- a/drivers/net/phy/motorcomm.c
+++ b/drivers/net/phy/motorcomm.c
@@ -6,6 +6,7 @@
  * Author: Frank <Frank.Sae@motor-comm.com>
  */
 
+#include <linux/clk.h>
 #include <linux/etherdevice.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -1053,6 +1054,7 @@ static int yt8521_probe(struct phy_device *phydev)
 {
 	struct device *dev = &phydev->mdio.dev;
 	struct yt8521_priv *priv;
+	struct clk *clk;
 	int chip_config;
 	u16 mask, val;
 	u32 freq;
@@ -1064,6 +1066,12 @@ static int yt8521_probe(struct phy_device *phydev)
 
 	phydev->priv = priv;
 
+	/* A crystal-less PHY is fed its 25 MHz reference from the SoC. */
+	clk = devm_clk_get_optional_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "failed to get and enable the reference clock\n");
+
 	chip_config = ytphy_read_ext_with_lock(phydev, YT8521_CHIP_CONFIG_REG);
 	if (chip_config < 0)
 		return chip_config;
@@ -1169,9 +1177,16 @@ static int yt8521_probe(struct phy_device *phydev)
 static int yt8531_probe(struct phy_device *phydev)
 {
 	struct device *dev = &phydev->mdio.dev;
+	struct clk *clk;
 	u16 mask, val;
 	u32 freq;
 
+	/* A crystal-less PHY is fed its 25 MHz reference from the SoC. */
+	clk = devm_clk_get_optional_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "failed to get and enable the reference clock\n");
+
 	if (device_property_read_u32(dev, "motorcomm,clk-out-frequency-hz", &freq))
 		freq = YTPHY_DTS_OUTPUT_CLK_DIS;
 
-- 
2.43.0