From ac68902259dcb908cf7bc5935c256c34c4eab4db Mon Sep 17 00:00:00 2001
From: Heinrich Toews <ht@twx-software.de>
Date: Thu, 27 Nov 2025 16:06:06 +0100
Subject: [PATCH] net: dsa: microchip: ksz_common: add single led mode support
 for ksz9477

Signed-off-by: Heinrich Toews <ht@twx-software.de>
---
 drivers/net/dsa/microchip/ksz_common.c | 41 ++++++++++++++++++++++++++
 drivers/net/dsa/microchip/ksz_common.h |  4 +++
 2 files changed, 45 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 7d382ec38356..2d0a8d9e4cc1 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -447,6 +447,9 @@ static const u16 ksz9477_regs[] = {
 	[S_MULTICAST_CTRL]		= 0x0331,
 	[P_XMII_CTRL_0]			= 0x0300,
 	[P_XMII_CTRL_1]			= 0x0301,
+	[P_PHY_MMD_SETUP]		= 0x011A,
+	[P_PHY_MMD_DATA]		= 0x011C,
+	[P_PHY_DIGITAL_DEBUG_3]		= 0x013C,
 };
 
 static const u32 ksz9477_masks[] = {
@@ -2955,6 +2958,39 @@ static void ksz_set_gbit(struct ksz_device *dev, int port, bool gbit)
 	ksz_pwrite8(dev, port, regs[P_XMII_CTRL_1], data8);
 }
 
+static void ksz_enable_single_led_mode(struct ksz_device *dev, int port)
+{
+	const u16 *regs = dev->info->regs;
+	u16 data16;
+
+	dev_info(dev->dev, "port-%d: enable single-led mode.\n", port);
+
+	/* Set up register address for MMD */
+	data16 = 0x0002;
+	ksz_pwrite16(dev, port, regs[P_PHY_MMD_SETUP], data16);
+
+	/* Select Register 00h of MMD */
+	data16 = 0x0000;
+	ksz_pwrite16(dev, port, regs[P_PHY_MMD_DATA], data16);
+
+	/* Select register data for MMD */
+	data16 = 0x4002;
+	ksz_pwrite16(dev, port, regs[P_PHY_MMD_SETUP], data16);
+
+	/* Write value 0010h to MMD */
+	data16 = 0x0011;
+	ksz_pwrite16(dev, port, regs[P_PHY_MMD_DATA], data16);
+
+	/* Due to Errata Module 19 this workaround is needed to
+	 * enable single-led mode. It has also to be a 32bit
+	 * write.
+	 */
+	dev_info(dev->dev, "port-%d: applying errata (Module 19) " \
+		 "workaround.\n", port);
+	data16 = 0xfa00;
+	ksz_pwrite16(dev, port, regs[P_PHY_DIGITAL_DEBUG_3], data16);
+}
+
 static void ksz_set_100_10mbit(struct ksz_device *dev, int port, int speed)
 {
 	const u8 *bitval = dev->info->xmii_ctrl0;
@@ -3020,6 +3056,9 @@ static void ksz9477_phylink_mac_link_up(struct ksz_device *dev, int port,
 {
 	struct ksz_port *p;
 
+	if (dev->single_led_mode && port != dev->cpu_port)
+		ksz_enable_single_led_mode(dev, port);
+
 	p = &dev->ports[port];
 
 	/* Internal PHYs */
@@ -3744,6 +3783,8 @@ int ksz_switch_register(struct ksz_device *dev)
 		ret = of_property_read_u8(dev->dev->of_node, "microchip,led-mode", &dev->led_mode);
 		if (ret)
 			dev->led_mode = 0;
+		dev->single_led_mode = of_property_read_bool(dev->dev->of_node,
+								  "microchip,single-led-mode");
 	}
 
 	ret = dsa_register_switch(dev->ds);
diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 25391fa8a087..813f37fc9fb3 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -150,6 +150,7 @@ struct ksz_device {
 	struct gpio_desc *reset_gpio;	/* Optional reset GPIO */
 	bool disable_internal_ldo;	/* Disable internal 1.8V LDO */
 	u8 led_mode;
+	bool single_led_mode;		/* Enable Single LED Mode */
 	/* chip specific data */
 	u32 chip_id;
 	u8 chip_rev;
@@ -232,6 +233,9 @@ enum ksz_regs {
 	S_MULTICAST_CTRL,
 	P_XMII_CTRL_0,
 	P_XMII_CTRL_1,
+	P_PHY_MMD_SETUP,
+	P_PHY_MMD_DATA,
+	P_PHY_DIGITAL_DEBUG_3,
 };
 
 enum ksz_masks {