[PATCH net-next v10 3/5] net: phy: micrel: Add loopback support

Gerhard Engleder
2025-03-12T20:30:26Z

The KSZ9031 PHYs requires full duplex for loopback mode. Add PHY
specific set_loopback() to ensure this.

Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
---
drivers/net/phy/micrel.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 289e1d56aa65..24882d30f685 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1032,6 +1032,29 @@ static int ksz9021_config_init(struct phy_device *phydev)
#define MII_KSZ9031RN_EDPD 0x23
#define MII_KSZ9031RN_EDPD_ENABLE BIT(0)

+static int ksz9031_set_loopback(struct phy_device *phydev, bool enable,
+ int speed)
+{
+ u16 ctl = BMCR_LOOPBACK;
+ int val;
+
+ if (!enable)
+ return genphy_loopback(phydev, enable, 0);
+
+ if (speed == SPEED_10 || speed == SPEED_100 || speed == SPEED_1000)
+ phydev->speed = speed;
+ else if (speed)
+ return -EINVAL;
+ phydev->duplex = DUPLEX_FULL;
+
+ ctl |= mii_bmcr_encode_fixed(phydev->speed, phydev->duplex);
+
+ phy_write(phydev, MII_BMCR, ctl);
+
+ return phy_read_poll_timeout(phydev, MII_BMSR, val, val & BMSR_LSTATUS,
+ 5000, 500000, true);
+}
+
static int ksz9031_of_load_skew_values(struct phy_device *phydev,
const struct device_node *of_node,
u16 reg, size_t field_sz,
@@ -5565,6 +5588,7 @@ static struct phy_driver ksphy_driver[] = {
.resume = kszphy_resume,
.cable_test_start = ksz9x31_cable_test_start,
.cable_test_get_status = ksz9x31_cable_test_get_status,
+ .set_loopback = ksz9031_set_loopback,
}, {
.phy_id = PHY_ID_LAN8814,
.phy_id_mask = MICREL_PHY_ID_MASK,
--
2.39.5