net: phy: Add helper for getting MAC termination resistance

Add helper which returns the MAC termination resistance value. Modifying
the resistance to an appropriate value can reduce signal reflections and
therefore improve signal quality.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
Link: https://patch.msgid.link/20250416-dp83822-mac-impedance-v3-3-028ac426cddb@liebherr.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index cc6c209fe702293c25e619899a699a53638f0f66..f85c172c446c56e1da1d13baa18c581f2213dcc5 100644 (file)
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2975,6 +2975,21 @@ int phy_get_tx_amplitude_gain(struct phy_device *phydev, struct device *dev,
 }
 EXPORT_SYMBOL_GPL(phy_get_tx_amplitude_gain);
 
+/**
+ * phy_get_mac_termination - stores MAC termination in @val
+ * @phydev: phy_device struct
+ * @dev: pointer to the devices device struct
+ * @val: MAC termination
+ *
+ * Returns: 0 on success, < 0 on failure
+ */
+int phy_get_mac_termination(struct phy_device *phydev, struct device *dev,
+                           u32 *val)
+{
+       return phy_get_u32_property(dev, "mac-termination-ohms", val);
+}
+EXPORT_SYMBOL_GPL(phy_get_mac_termination);
+
 static int phy_led_set_brightness(struct led_classdev *led_cdev,
                                  enum led_brightness value)
 {

diff --git a/include/linux/phy.h b/include/linux/phy.h
index fb755358d965b728d502bfc1c0d6e5a6b779f1ef..066a28a4b64b25a7c6033a3bb1e3bc48b20c96dc 100644 (file)
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -2040,6 +2040,9 @@ int phy_get_tx_amplitude_gain(struct phy_device *phydev, struct device *dev,
                              enum ethtool_link_mode_bit_indices linkmode,
                              u32 *val);
 
+int phy_get_mac_termination(struct phy_device *phydev, struct device *dev,
+                           u32 *val);
+
 void phy_resolve_pause(unsigned long *local_adv, unsigned long *partner_adv,
                       bool *tx_pause, bool *rx_pause);