[PATCH net-next] net: phy: motorcomm: Add cable test support for internal YT861x PHYs

[PATCH net-next] net: phy: motorcomm: Add cable test support for internal YT861x PHYs

[David Yang]

The YT921x switches integrate GbE PHYs of the YT861x family (PHY ID
0x01e04281) on the switch-internal MDIO bus exposed by the yt921x DSA
driver. Without a specific driver they bind to the generic PHY driver
and lack the cable diagnostic facility. Add a driver entry for them
with cable test support.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/phy/motorcomm.c | 119 +++++++++++++++++++++++++++++++++++-
 1 file changed, 117 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
index 90a4f86f2758..ef15fef304aa 100644
--- a/drivers/net/phy/motorcomm.c
+++ b/drivers/net/phy/motorcomm.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
- * Motorcomm 8511/8521/8522/8531/8531S/8821 PHY driver.
+ * Motorcomm 8511/8521/8522/8531/8531S/861x/8821 PHY driver.
  *
  * Author: Peter Geis <pgwipeout@gmail.com>
  * Author: Frank <Frank.Sae@motor-comm.com>
@@ -8,6 +8,7 @@
 
 #include <linux/clk.h>
 #include <linux/etherdevice.h>
+#include <linux/ethtool_netlink.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/phy.h>
@@ -18,7 +19,9 @@
 #define PHY_ID_YT8522		0x4f51e928
 #define PHY_ID_YT8531		0x4f51e91b
 #define PHY_ID_YT8531S		0x4f51e91a
+#define PHY_ID_INT861X		0x01e04281
 #define PHY_ID_YT8821		0x4f51ea19
+
 /* YT8521/YT8531S/YT8821 Register Overview
  *	UTP Register space	|	FIBER Register space
  *  ------------------------------------------------------------
@@ -298,6 +301,19 @@
 #define YT8531_SCR_CLK_SRC_REF_25M		4
 #define YT8531_SCR_CLK_SRC_SSC_25M		5
 
+/* TDR (cable diagnostic) test control */
+#define YT861X_TDR_CTRL_REG			0x80
+#define YT861X_TDR_CTRL_START			BIT(0)
+
+#define YT861X_TDR_STATUS_REG			0x84
+#define YT861X_TDR_STATUS_BUSY			BIT(15)
+#define YT861X_TDR_STATUS_PAIR_OK		0
+#define YT861X_TDR_STATUS_PAIR_UNKNOWN		1
+#define YT861X_TDR_STATUS_PAIR_SHORT		2
+#define YT861X_TDR_STATUS_PAIR_OPEN		3
+
+#define YT861X_TDR_PAIR_LENGTH_REG(n)		(0x87 + (n))	/* in cm */
+
 #define YT8821_SDS_EXT_CSR_CTRL_REG			0x23
 #define YT8821_SDS_EXT_CSR_VCO_LDO_EN			BIT(15)
 #define YT8821_SDS_EXT_CSR_VCO_BIAS_LPF_EN		BIT(8)
@@ -2538,6 +2554,95 @@ static int yt8521_get_features(struct phy_device *phydev)
 	return ret;
 }
 
+/**
+ * yt861x_cable_test_start() - start a cable diagnostic (TDR) test
+ * @phydev: a pointer to a &struct phy_device
+ *
+ * Returns: 0 or negative errno code
+ */
+static int yt861x_cable_test_start(struct phy_device *phydev)
+{
+	int ret;
+
+	/* auto sleep would abort the TDR test */
+	ret = ytphy_modify_ext_with_lock(phydev,
+					 YT8521_EXTREG_SLEEP_CONTROL1_REG,
+					 YT8521_ESC1R_SLEEP_SW, 0);
+	if (ret)
+		return ret;
+
+	return ytphy_write_ext_with_lock(phydev, YT861X_TDR_CTRL_REG,
+					 YT861X_TDR_CTRL_START);
+}
+
+/**
+ * yt861x_cable_test_get_status() - report cable diagnostic test results
+ * @phydev: a pointer to a &struct phy_device
+ * @finished: set to true when the test is complete
+ *
+ * Returns: 0 or negative errno code
+ */
+static int yt861x_cable_test_get_status(struct phy_device *phydev,
+					bool *finished)
+{
+	int ret;
+
+	*finished = false;
+
+	ret = ytphy_read_ext_with_lock(phydev, YT861X_TDR_STATUS_REG);
+	if (ret < 0)
+		return ret;
+
+	if (ret & YT861X_TDR_STATUS_BUSY)
+		return 0;
+
+	for (int pair = ETHTOOL_A_CABLE_PAIR_A; pair <= ETHTOOL_A_CABLE_PAIR_D;
+	     pair++) {
+		u8 code;
+
+		switch ((ret >> (2 * pair)) & 0x3) {
+		case YT861X_TDR_STATUS_PAIR_OK:
+			code = ETHTOOL_A_CABLE_RESULT_CODE_OK;
+			break;
+		case YT861X_TDR_STATUS_PAIR_SHORT:
+			code = ETHTOOL_A_CABLE_RESULT_CODE_SAME_SHORT;
+			break;
+		case YT861X_TDR_STATUS_PAIR_OPEN:
+			code = ETHTOOL_A_CABLE_RESULT_CODE_OPEN;
+			break;
+		default:
+			code = ETHTOOL_A_CABLE_RESULT_CODE_UNSPEC;
+		}
+
+		ethnl_cable_test_result(phydev, pair, code);
+
+		if (code != ETHTOOL_A_CABLE_RESULT_CODE_OK &&
+		    code != ETHTOOL_A_CABLE_RESULT_CODE_UNSPEC) {
+			ret = ytphy_read_ext_with_lock(phydev,
+						       YT861X_TDR_PAIR_LENGTH_REG(pair));
+			if (ret >= 0)
+				ethnl_cable_test_fault_length(phydev, pair,
+							      ret);
+		}
+	}
+
+	/* restore auto sleep and restart the PHY to resume the link */
+	ret = ytphy_modify_ext_with_lock(phydev,
+					 YT8521_EXTREG_SLEEP_CONTROL1_REG,
+					 YT8521_ESC1R_SLEEP_SW,
+					 YT8521_ESC1R_SLEEP_SW);
+	if (ret)
+		return ret;
+
+	ret = genphy_soft_reset(phydev);
+	if (ret)
+		return ret;
+
+	*finished = true;
+
+	return 0;
+}
+
 /**
  * yt8821_get_features - read mmd register to get 2.5G capability
  * @phydev: target phy_device struct
@@ -3173,6 +3278,15 @@ static struct phy_driver motorcomm_phy_drvs[] = {
 		.suspend	= yt8521_suspend,
 		.resume		= yt8521_resume,
 	},
+	{
+		PHY_ID_MATCH_EXACT(PHY_ID_INT861X),
+		.name			= "Internal YT861x Gigabit Ethernet",
+		.soft_reset		= genphy_soft_reset,
+		.suspend		= genphy_suspend,
+		.resume			= genphy_resume,
+		.cable_test_start	= yt861x_cable_test_start,
+		.cable_test_get_status	= yt861x_cable_test_get_status,
+	},
 	{
 		PHY_ID_MATCH_EXACT(PHY_ID_YT8821),
 		.name			= "YT8821 2.5Gbps PHY",
@@ -3194,7 +3308,7 @@ static struct phy_driver motorcomm_phy_drvs[] = {
 
 module_phy_driver(motorcomm_phy_drvs);
 
-MODULE_DESCRIPTION("Motorcomm 8511/8521/8531/8531S/8821 PHY driver");
+MODULE_DESCRIPTION("Motorcomm 8511/8521/8531/8531S/861x/8821 PHY driver");
 MODULE_AUTHOR("Peter Geis");
 MODULE_AUTHOR("Frank");
 MODULE_LICENSE("GPL");
@@ -3205,6 +3319,7 @@ static const struct mdio_device_id __maybe_unused motorcomm_tbl[] = {
 	{ PHY_ID_MATCH_EXACT(PHY_ID_YT8522) },
 	{ PHY_ID_MATCH_EXACT(PHY_ID_YT8531) },
 	{ PHY_ID_MATCH_EXACT(PHY_ID_YT8531S) },
+	{ PHY_ID_MATCH_EXACT(PHY_ID_INT861X) },
 	{ PHY_ID_MATCH_EXACT(PHY_ID_YT8821) },
 	{ /* sentinel */ }
 };
-- 
2.53.0

Re: [PATCH net-next] net: phy: motorcomm: Add cable test support for internal YT861x PHYs

[Andrew Lunn]

On Mon, Oct 05, 2026 at 02:42:43AM +0800, David Yang wrote:
> The YT921x switches integrate GbE PHYs of the YT861x family (PHY ID
> 0x01e04281) on the switch-internal MDIO bus exposed by the yt921x DSA
> driver. Without a specific driver they bind to the generic PHY driver
> and lack the cable diagnostic facility. Add a driver entry for them
> with cable test support.

Since this does two different things, it should be two patches.

Does the cable test code apply to other devices this driver drive?

> @@ -18,7 +19,9 @@
>  #define PHY_ID_YT8522		0x4f51e928
>  #define PHY_ID_YT8531		0x4f51e91b
>  #define PHY_ID_YT8531S		0x4f51e91a
> +#define PHY_ID_INT861X		0x01e04281

Is this the ID of the switch itself? It does not match the pattern.

>  #define PHY_ID_YT8821		0x4f51ea19

	Andrew

Re: [PATCH net-next] net: phy: motorcomm: Add cable test support for internal YT861x PHYs

[David Yang]

On Mon, Oct 5, 2026 at 4:17 AM Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Mon, Oct 05, 2026 at 02:42:43AM +0800, David Yang wrote:
> > The YT921x switches integrate GbE PHYs of the YT861x family (PHY ID
> > 0x01e04281) on the switch-internal MDIO bus exposed by the yt921x DSA
> > driver. Without a specific driver they bind to the generic PHY driver
> > and lack the cable diagnostic facility. Add a driver entry for them
> > with cable test support.
>
> Since this does two different things, it should be two patches.
>
> Does the cable test code apply to other devices this driver drive?

I don't have other devices to test with.

> > @@ -18,7 +19,9 @@
> >  #define PHY_ID_YT8522                0x4f51e928
> >  #define PHY_ID_YT8531                0x4f51e91b
> >  #define PHY_ID_YT8531S               0x4f51e91a
> > +#define PHY_ID_INT861X               0x01e04281
>
> Is this the ID of the switch itself? It does not match the pattern.

It's live captured from the system. By the way the serdes PCS does
show something matching the pattern 0x4f51e899.

> >  #define PHY_ID_YT8821                0x4f51ea19
>
>         Andrew