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net: phy: micrel: expose KSZ87xx low-loss cable tunables

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Add support for the KSZ87xx low-loss cable PHY tunables in the Micrel
PHY driver by implementing get_tunable and set_tunable callbacks.

These callbacks expose vendor-specific PHY tunables used to control the
KSZ87xx embedded PHY receiver behavior when operating with short or
low-loss Ethernet cables. The tunables provide:

- a boolean short-cable preset applying known good settings;
- an integer LPF bandwidth control;
- an integer DSP EQ initial value control.

The Micrel PHY driver forwards these tunables via standard phy_read() /
phy_write() operations, which are virtualized by the KSZ8 DSA driver and
translated into the appropriate indirect switch register accesses.

Reviewed-by: Marek Vasut <marex@nabladev.com>
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Fidelio Lawson <fidelio.lawson@exotec.com>
Link: https://patch.msgid.link/20260609-ksz87xx_errata_low_loss_connections-v10-3-9ba4418cf3db@exotec.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Fidelio Lawson
2026-06-09 18:19:57 +02:00
committed by Jakub Kicinski
parent 13655144dd
commit a1ee1b9beb
1 changed files with 61 additions and 0 deletions
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61
drivers/net/phy/micrel.c
View File

@@ -287,6 +287,12 @@
/* PHY Control 2 / PHY Control (if no PHY Control 1) */
#define MII_KSZPHY_CTRL_2 0x1f
#define MII_KSZPHY_CTRL MII_KSZPHY_CTRL_2
/* Vendor-specific Clause 22 register, virtualized by KSZ87xx embedded PHYs DSA driver */
#define MII_KSZ87XX_SHORT_CABLE 0x1a
#define MII_KSZ87XX_LPF_BW 0x1b
#define MII_KSZ87XX_EQ_INIT 0x1c
/* bitmap of PHY register to set interrupt mode */
#define KSZ8081_CTRL2_HP_MDIX BIT(15)
#define KSZ8081_CTRL2_MDI_MDI_X_SELECT BIT(14)
@@ -940,6 +946,59 @@ static int ksz8795_match_phy_device(struct phy_device *phydev,
return ksz8051_ksz8795_match_phy_device(phydev, false);
}
static int ksz8795_get_tunable(struct phy_device *phydev,
struct ethtool_tunable *tuna, void *data)
{
int ret;
switch (tuna->id) {
case ETHTOOL_PHY_SHORT_CABLE_PRESET:
ret = phy_read(phydev, MII_KSZ87XX_SHORT_CABLE);
if (ret < 0)
return ret;
*(u8 *)data = ret;
return 0;
case ETHTOOL_PHY_LPF_BW:
ret = phy_read(phydev, MII_KSZ87XX_LPF_BW);
if (ret < 0)
return ret;
*(u32 *)data = ret & 0xff;
return 0;
case ETHTOOL_PHY_DSP_EQ_INIT_VALUE:
ret = phy_read(phydev, MII_KSZ87XX_EQ_INIT);
if (ret < 0)
return ret;
*(u32 *)data = ret & 0xff;
return 0;
default:
return -EOPNOTSUPP;
}
}
static int ksz8795_set_tunable(struct phy_device *phydev,
struct ethtool_tunable *tuna, const void *data)
{
u32 val;
switch (tuna->id) {
case ETHTOOL_PHY_SHORT_CABLE_PRESET:
return phy_write(phydev, MII_KSZ87XX_SHORT_CABLE,
*(const u8 *)data);
case ETHTOOL_PHY_LPF_BW:
val = *(const u32 *)data;
if (val > 0xff)
return -EINVAL;
return phy_write(phydev, MII_KSZ87XX_LPF_BW, (u8)val);
case ETHTOOL_PHY_DSP_EQ_INIT_VALUE:
val = *(const u32 *)data;
if (val > 0xff)
return -EINVAL;
return phy_write(phydev, MII_KSZ87XX_EQ_INIT, (u8)val);
default:
return -EOPNOTSUPP;
}
}
static int ksz9021_load_values_from_of(struct phy_device *phydev,
const struct device_node *of_node,
u16 reg,
@@ -6961,6 +7020,8 @@ static struct phy_driver ksphy_driver[] = {
/* PHY_BASIC_FEATURES */
.config_init = kszphy_config_init,
.match_phy_device = ksz8795_match_phy_device,
.get_tunable = ksz8795_get_tunable,
.set_tunable = ksz8795_set_tunable,
.suspend = genphy_suspend,
.resume = genphy_resume,
}, {