Merge branch 'net-phy-dp83822-add-support-for-changing-the-transmit-amplitude-voltage'

Dimitri Fedrau via says:

====================
net: phy: dp83822: Add support for changing the transmit amplitude voltage

Add support for changing the transmit amplitude voltage in 100BASE-TX mode.
Add support for configuration via DT.

v4: https://lore.kernel.org/20250211-dp83822-tx-swing-v4-0-1e8ebd71ad54@liebherr.com
v3: https://lore.kernel.org/20250204-dp83822-tx-swing-v3-0-9798e96500d9@liebherr.com
v2: https://lore.kernel.org/20250120-dp83822-tx-swing-v2-0-07c99dc42627@liebherr.com
v1: https://lore.kernel.org/20250113-dp83822-tx-swing-v1-0-7ed5a9d80010@liebherr.com
====================

Link: https://patch.msgid.link/20250214-dp83822-tx-swing-v5-0-02ca72620599@liebherr.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 83 insertions, 18 deletions

diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
index 2c71454ae8e3..824bbe4333b7 100644
--- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
@@ -232,6 +232,12 @@ properties:
       PHY's that have configurable TX internal delays. If this property is
       present then the PHY applies the TX delay.
 
+  tx-amplitude-100base-tx-percent:
+    description:
+      Transmit amplitude gain applied for 100BASE-TX. 100% matches 2V
+      peak-to-peak specified in ANSI X3.263. When omitted, the PHYs default
+      will be left as is.
+
   leds:
     type: object
 
diff --git a/drivers/net/phy/dp83822.c b/drivers/net/phy/dp83822.c
index 6599feca1967..3662f3905d5a 100644
--- a/drivers/net/phy/dp83822.c
+++ b/drivers/net/phy/dp83822.c
@@ -31,6 +31,7 @@
 #define MII_DP83822_RCSR	0x17
 #define MII_DP83822_RESET_CTRL	0x1f
 #define MII_DP83822_MLEDCR	0x25
+#define MII_DP83822_LDCTRL	0x403
 #define MII_DP83822_LEDCFG1	0x460
 #define MII_DP83822_IOCTRL1	0x462
 #define MII_DP83822_IOCTRL2	0x463
@@ -123,6 +124,9 @@
 #define DP83822_IOCTRL1_GPIO1_CTRL		GENMASK(2, 0)
 #define DP83822_IOCTRL1_GPIO1_CTRL_LED_1	BIT(0)
 
+/* LDCTRL bits */
+#define DP83822_100BASE_TX_LINE_DRIVER_SWING	GENMASK(7, 4)
+
 /* IOCTRL2 bits */
 #define DP83822_IOCTRL2_GPIO2_CLK_SRC		GENMASK(6, 4)
 #define DP83822_IOCTRL2_GPIO2_CTRL		GENMASK(2, 0)
@@ -197,6 +201,7 @@ struct dp83822_private {
 	bool set_gpio2_clk_out;
 	u32 gpio2_clk_out;
 	bool led_pin_enable[DP83822_MAX_LED_PINS];
+	int tx_amplitude_100base_tx_index;
 };
 
 static int dp83822_config_wol(struct phy_device *phydev,
@@ -522,6 +527,12 @@ static int dp83822_config_init(struct phy_device *phydev)
 			       FIELD_PREP(DP83822_IOCTRL2_GPIO2_CLK_SRC,
 					  dp83822->gpio2_clk_out));
 
+	if (dp83822->tx_amplitude_100base_tx_index >= 0)
+		phy_modify_mmd(phydev, MDIO_MMD_VEND2, MII_DP83822_LDCTRL,
+			       DP83822_100BASE_TX_LINE_DRIVER_SWING,
+			       FIELD_PREP(DP83822_100BASE_TX_LINE_DRIVER_SWING,
+					  dp83822->tx_amplitude_100base_tx_index));
+
 	err = dp83822_config_init_leds(phydev);
 	if (err)
 		return err;
@@ -720,6 +731,11 @@ static int dp83822_phy_reset(struct phy_device *phydev)
 }
 
 #ifdef CONFIG_OF_MDIO
+static const u32 tx_amplitude_100base_tx_gain[] = {
+	80, 82, 83, 85, 87, 88, 90, 92,
+	93, 95, 97, 98, 100, 102, 103, 105,
+};
+
 static int dp83822_of_init_leds(struct phy_device *phydev)
 {
 	struct device_node *node = phydev->mdio.dev.of_node;
@@ -780,6 +796,8 @@ static int dp83822_of_init(struct phy_device *phydev)
 	struct dp83822_private *dp83822 = phydev->priv;
 	struct device *dev = &phydev->mdio.dev;
 	const char *of_val;
+	int i, ret;
+	u32 val;
 
 	/* Signal detection for the PHY is only enabled if the FX_EN and the
 	 * SD_EN pins are strapped. Signal detection can only enabled if FX_EN
@@ -815,6 +833,26 @@ static int dp83822_of_init(struct phy_device *phydev)
 		dp83822->set_gpio2_clk_out = true;
 	}
 
+	dp83822->tx_amplitude_100base_tx_index = -1;
+	ret = phy_get_tx_amplitude_gain(phydev, dev,
+					ETHTOOL_LINK_MODE_100baseT_Full_BIT,
+					&val);
+	if (!ret) {
+		for (i = 0; i < ARRAY_SIZE(tx_amplitude_100base_tx_gain); i++) {
+			if (tx_amplitude_100base_tx_gain[i] == val) {
+				dp83822->tx_amplitude_100base_tx_index = i;
+				break;
+			}
+		}
+
+		if (dp83822->tx_amplitude_100base_tx_index < 0) {
+			phydev_err(phydev,
+				   "Invalid value for tx-amplitude-100base-tx-percent property (%u)\n",
+				   val);
+			return -EINVAL;
+		}
+	}
+
 	return dp83822_of_init_leds(phydev);
 }
 
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 35ec99b4dc51..0d56e7c7f98c 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -3096,19 +3096,12 @@ void phy_get_pause(struct phy_device *phydev, bool *tx_pause, bool *rx_pause)
 EXPORT_SYMBOL(phy_get_pause);
 
 #if IS_ENABLED(CONFIG_OF_MDIO)
-static int phy_get_int_delay_property(struct device *dev, const char *name)
+static int phy_get_u32_property(struct device *dev, const char *name, u32 *val)
 {
-	s32 int_delay;
-	int ret;
-
-	ret = device_property_read_u32(dev, name, &int_delay);
-	if (ret)
-		return ret;
-
-	return int_delay;
+	return device_property_read_u32(dev, name, val);
 }
 #else
-static int phy_get_int_delay_property(struct device *dev, const char *name)
+static int phy_get_u32_property(struct device *dev, const char *name, u32 *val)
 {
 	return -EINVAL;
 }
@@ -3133,12 +3126,12 @@ static int phy_get_int_delay_property(struct device *dev, const char *name)
 s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 			   const int *delay_values, int size, bool is_rx)
 {
-	s32 delay;
-	int i;
+	int i, ret;
+	u32 delay;
 
 	if (is_rx) {
-		delay = phy_get_int_delay_property(dev, "rx-internal-delay-ps");
-		if (delay < 0 && size == 0) {
+		ret = phy_get_u32_property(dev, "rx-internal-delay-ps", &delay);
+		if (ret < 0 && size == 0) {
 			if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
 			    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID)
 				return 1;
@@ -3147,8 +3140,8 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 		}
 
 	} else {
-		delay = phy_get_int_delay_property(dev, "tx-internal-delay-ps");
-		if (delay < 0 && size == 0) {
+		ret = phy_get_u32_property(dev, "tx-internal-delay-ps", &delay);
+		if (ret < 0 && size == 0) {
 			if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
 			    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
 				return 1;
@@ -3157,8 +3150,8 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 		}
 	}
 
-	if (delay < 0)
-		return delay;
+	if (ret < 0)
+		return ret;
 
 	if (size == 0)
 		return delay;
@@ -3193,6 +3186,30 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 }
 EXPORT_SYMBOL(phy_get_internal_delay);
 
+/**
+ * phy_get_tx_amplitude_gain - stores tx amplitude gain in @val
+ * @phydev: phy_device struct
+ * @dev: pointer to the devices device struct
+ * @linkmode: linkmode for which the tx amplitude gain should be retrieved
+ * @val: tx amplitude gain
+ *
+ * Returns: 0 on success, < 0 on failure
+ */
+int phy_get_tx_amplitude_gain(struct phy_device *phydev, struct device *dev,
+			      enum ethtool_link_mode_bit_indices linkmode,
+			      u32 *val)
+{
+	switch (linkmode) {
+	case ETHTOOL_LINK_MODE_100baseT_Full_BIT:
+		return phy_get_u32_property(dev,
+					    "tx-amplitude-100base-tx-percent",
+					    val);
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL_GPL(phy_get_tx_amplitude_gain);
+
 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 3665cdd610a3..70c632799082 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -2097,6 +2097,10 @@ void phy_get_pause(struct phy_device *phydev, bool *tx_pause, bool *rx_pause);
 s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 			   const int *delay_values, int size, bool is_rx);
 
+int phy_get_tx_amplitude_gain(struct phy_device *phydev, struct device *dev,
+			      enum ethtool_link_mode_bit_indices linkmode,
+			      u32 *val);
+
 void phy_resolve_pause(unsigned long *local_adv, unsigned long *partner_adv,
 		       bool *tx_pause, bool *rx_pause);