The ethernet controller on Spacemit K3 SoC is Synopsys DesignWare
MAC (version 5.40a), with the following special points:
1. The rate of the tx clock line is auto changed when the mac speed
   rate is changed, and no need for changing the input tx clock.
2. This controller require a extra syscon device to configure the
   interface type, enable wake up interrupt and delay configuration
   if needed.

Add Spacemit dwmac driver support on the Spacemit K3 SoC.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/Kconfig   |  12 +
 drivers/net/ethernet/stmicro/stmmac/Makefile  |   1 +
 .../ethernet/stmicro/stmmac/dwmac-spacemit.c  | 227 ++++++++++++++++++
 3 files changed, 240 insertions(+)
 create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c

diff --git a/drivers/net/ethernet/stmicro/stmmac/Kconfig b/drivers/net/ethernet/stmicro/stmmac/Kconfig
index 07088d03dbab..d3a6ab7383fc 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Kconfig
+++ b/drivers/net/ethernet/stmicro/stmmac/Kconfig
@@ -216,6 +216,18 @@ config DWMAC_SOPHGO
 	  for the stmmac device driver. This driver is used for the
 	  ethernet controllers on various Sophgo SoCs.
 
+config DWMAC_SPACEMIT
+	tristate "Spacemit dwmac support"
+	depends on OF && (ARCH_SPACEMIT || COMPILE_TEST)
+	select MFD_SYSCON
+	default m if ARCH_SPACEMIT
+	help
+	  Support for ethernet controllers on Spacemit RISC-V SoCs
+
+	  This selects the Spacemit platform specific glue layer support
+	  for the stmmac device driver. This driver is used for the
+	  Spacemit K3 ethernet controllers.
+
 config DWMAC_STARFIVE
 	tristate "StarFive dwmac support"
 	depends on OF && (ARCH_STARFIVE || COMPILE_TEST)
diff --git a/drivers/net/ethernet/stmicro/stmmac/Makefile b/drivers/net/ethernet/stmicro/stmmac/Makefile
index c9263987ef8d..945c5354eced 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Makefile
+++ b/drivers/net/ethernet/stmicro/stmmac/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_DWMAC_RZN1)	+= dwmac-rzn1.o
 obj-$(CONFIG_DWMAC_S32)		+= dwmac-s32.o
 obj-$(CONFIG_DWMAC_SOCFPGA)	+= dwmac-altr-socfpga.o
 obj-$(CONFIG_DWMAC_SOPHGO)	+= dwmac-sophgo.o
+obj-$(CONFIG_DWMAC_SPACEMIT)	+= dwmac-spacemit.o
 obj-$(CONFIG_DWMAC_STARFIVE)	+= dwmac-starfive.o
 obj-$(CONFIG_DWMAC_STI)		+= dwmac-sti.o
 obj-$(CONFIG_DWMAC_STM32)	+= dwmac-stm32.o
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c
new file mode 100644
index 000000000000..f6379ae6e858
--- /dev/null
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Spacemit DWMAC platform driver
+ *
+ * Copyright (C) 2026 Inochi Amaoto <inochiama@gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/math.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#include "stmmac_platform.h"
+
+/* ctrl register bits */
+#define CTRL_PHY_INTF_RGMII		BIT(3)
+#define CTRL_PHY_INTF_MII		BIT(4)
+#define CTRL_WAKE_IRQ_EN		BIT(9)
+#define CTRL_PHY_IRQ_EN			BIT(12)
+
+/* dline register bits */
+#define RGMII_RX_DLINE_EN		BIT(0)
+#define RGMII_RX_DLINE_STEP		GENMASK(5, 4)
+#define RGMII_RX_DLINE_CODE		GENMASK(15, 8)
+#define RGMII_TX_DLINE_EN		BIT(16)
+#define RGMII_TX_DLINE_STEP		GENMASK(21, 20)
+#define RGMII_TX_DLINE_CODE		GENMASK(31, 24)
+
+#define MAX_DLINE_DELAY_CODE		0xff
+#define MAX_WORKED_DELAY		2800
+/* Note: the delay step value is at 0.1ps */
+#define K3_DELAY_STEP			367
+
+struct spacmit_dwmac {
+	struct regmap *apmu;
+	unsigned int ctrl_offset;
+	unsigned int dline_offset;
+};
+
+static int spacemit_dwmac_set_delay(struct spacmit_dwmac *dwmac,
+				    unsigned int tx_code, unsigned int rx_code)
+{
+	unsigned int mask, val;
+
+	mask = RGMII_TX_DLINE_STEP | RGMII_TX_DLINE_CODE | RGMII_TX_DLINE_EN |
+	       RGMII_RX_DLINE_STEP | RGMII_RX_DLINE_CODE | RGMII_RX_DLINE_EN;
+
+	/*
+	 * Since the delay step provided by config 0 is small enough, and
+	 * it can cover the range of the valid delay, so there is no needed
+	 * to use other step config.
+	 */
+	val = FIELD_PREP(RGMII_TX_DLINE_STEP, 0) |
+	      FIELD_PREP(RGMII_TX_DLINE_CODE, tx_code) | RGMII_TX_DLINE_EN |
+	      FIELD_PREP(RGMII_RX_DLINE_STEP, 0) |
+	      FIELD_PREP(RGMII_RX_DLINE_CODE, rx_code) | RGMII_RX_DLINE_EN;
+
+	return regmap_update_bits(dwmac->apmu, dwmac->dline_offset,
+				  mask, val);
+}
+
+static int spacemit_dwmac_detected_delay_value(unsigned int delay)
+{
+	if (delay == 0)
+		return 0;
+
+	if (delay > MAX_WORKED_DELAY)
+		return -EINVAL;
+
+	/*
+	 * Note K3 require a specific factor for calculate
+	 * the delay, in this scenario it is 0.9. So the
+	 * formula is code * step / 10 * 0.9
+	 */
+	return DIV_ROUND_CLOSEST(delay * 10 * 10, K3_DELAY_STEP * 9);
+}
+
+static int spacemit_dwmac_fix_delay(struct spacmit_dwmac *dwmac,
+				    unsigned int tx_delay,
+				    unsigned int rx_delay)
+{
+	int rx_code;
+	int tx_code;
+
+	rx_code = spacemit_dwmac_detected_delay_value(rx_delay);
+	if (rx_code < 0)
+		return rx_code;
+
+	tx_code = spacemit_dwmac_detected_delay_value(tx_delay);
+	if (tx_code < 0)
+		return tx_code;
+
+	return spacemit_dwmac_set_delay(dwmac, tx_code, rx_code);
+}
+
+static int spacemit_dwmac_update_irq_config(struct spacmit_dwmac *dwmac,
+					    struct stmmac_resources *stmmac_res)
+{
+	unsigned int mask = CTRL_WAKE_IRQ_EN;
+	unsigned int val = stmmac_res->wol_irq >= 0 ? CTRL_WAKE_IRQ_EN : 0;
+
+	return regmap_update_bits(dwmac->apmu, dwmac->ctrl_offset,
+				  mask, val);
+}
+
+static void spacemit_get_interfaces(struct stmmac_priv *priv, void *bsp_priv,
+				    unsigned long *interfaces)
+{
+	__set_bit(PHY_INTERFACE_MODE_MII, interfaces);
+	__set_bit(PHY_INTERFACE_MODE_RMII, interfaces);
+	phy_interface_set_rgmii(interfaces);
+}
+
+static int spacemit_set_phy_intf_sel(void *bsp_priv, u8 phy_intf_sel)
+{
+	struct spacmit_dwmac *dwmac = bsp_priv;
+	unsigned int mask = CTRL_PHY_INTF_MII | CTRL_PHY_INTF_RGMII;
+	unsigned int val = 0;
+
+	switch (phy_intf_sel) {
+	case PHY_INTF_SEL_GMII_MII:
+		val = CTRL_PHY_INTF_MII;
+		break;
+
+	case PHY_INTF_SEL_RMII:
+		break;
+
+	case PHY_INTF_SEL_RGMII:
+		val = CTRL_PHY_INTF_RGMII;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return regmap_update_bits(dwmac->apmu, dwmac->ctrl_offset,
+				  mask, val);
+}
+
+static int spacemit_dwmac_probe(struct platform_device *pdev)
+{
+	struct plat_stmmacenet_data *plat_dat;
+	struct stmmac_resources stmmac_res;
+	struct device *dev = &pdev->dev;
+	struct spacmit_dwmac *dwmac;
+	unsigned int offset[2];
+	struct regmap *apmu;
+	struct clk *clk_tx;
+	u32 rx_delay = 0;
+	u32 tx_delay = 0;
+	int ret;
+
+	ret = stmmac_get_platform_resources(pdev, &stmmac_res);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to get platform resources\n");
+
+	dwmac = devm_kzalloc(&pdev->dev, sizeof(*dwmac), GFP_KERNEL);
+	if (!dwmac)
+		return -ENOMEM;
+
+	plat_dat = devm_stmmac_probe_config_dt(pdev, stmmac_res.mac);
+	if (IS_ERR(plat_dat))
+		return dev_err_probe(dev, PTR_ERR(plat_dat),
+				     "failed to parse DT parameters\n");
+
+	clk_tx = devm_clk_get_enabled(&pdev->dev, "tx");
+	if (IS_ERR(clk_tx))
+		return dev_err_probe(&pdev->dev, PTR_ERR(clk_tx),
+				     "failed to get tx clock\n");
+
+	apmu = syscon_regmap_lookup_by_phandle_args(pdev->dev.of_node,
+						    "spacemit,apmu", 2,
+						    offset);
+	if (IS_ERR(apmu))
+		return dev_err_probe(dev, PTR_ERR(apmu),
+				"Failed to get apmu regmap\n");
+
+	dwmac->apmu = apmu;
+	dwmac->ctrl_offset = offset[0];
+	dwmac->dline_offset = offset[1];
+
+	ret = spacemit_dwmac_update_irq_config(dwmac, &stmmac_res);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to configure irq config\n");
+
+	of_property_read_u32(pdev->dev.of_node, "tx-internal-delay-ps",
+			     &tx_delay);
+	of_property_read_u32(pdev->dev.of_node, "rx-internal-delay-ps",
+			     &rx_delay);
+
+	plat_dat->get_interfaces = spacemit_get_interfaces;
+	plat_dat->set_phy_intf_sel = spacemit_set_phy_intf_sel;
+	plat_dat->bsp_priv = dwmac;
+
+	ret = spacemit_dwmac_fix_delay(dwmac, tx_delay, rx_delay);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to configure delay\n");
+
+	return stmmac_dvr_probe(dev, plat_dat, &stmmac_res);
+}
+
+static const struct of_device_id spacemit_dwmac_match[] = {
+	{ .compatible = "spacemit,k3-dwmac" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, spacemit_dwmac_match);
+
+static struct platform_driver spacemit_dwmac_driver = {
+	.probe  = spacemit_dwmac_probe,
+	.remove = stmmac_pltfr_remove,
+	.driver = {
+		.name = "spacemit-dwmac",
+		.pm = &stmmac_pltfr_pm_ops,
+		.of_match_table = spacemit_dwmac_match,
+	},
+};
+module_platform_driver(spacemit_dwmac_driver);
+
+MODULE_AUTHOR("Inochi Amaoto <inochiama@gmail.com>");
+MODULE_DESCRIPTION("Spacemit DWMAC platform driver");
+MODULE_LICENSE("GPL");
-- 
2.53.0

>  drivers/net/ethernet/stmicro/stmmac/Kconfig   |  12 +
>  drivers/net/ethernet/stmicro/stmmac/Makefile  |   1 +
>  .../ethernet/stmicro/stmmac/dwmac-spacemit.c  | 227 ++++++++++++++++++

One last point, please add another patch which adds a MAINTAINERS entry
for this file, so you can be Cc'd with future stmmac developments.

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

On Mon, Mar 09, 2026 at 11:59:17AM +0000, Russell King (Oracle) wrote:
> >  drivers/net/ethernet/stmicro/stmmac/Kconfig   |  12 +
> >  drivers/net/ethernet/stmicro/stmmac/Makefile  |   1 +
> >  .../ethernet/stmicro/stmmac/dwmac-spacemit.c  | 227 ++++++++++++++++++
> 
> One last point, please add another patch which adds a MAINTAINERS entry
> for this file, so you can be Cc'd with future stmmac developments.
> 
> Thanks.
> 

OK, I will add a MAINTAINERS entry for both this file and
binding file.

Regards,
Inochi

On Mon, Mar 09, 2026 at 08:42:44AM +0800, Inochi Amaoto wrote:
> +static int spacemit_dwmac_update_irq_config(struct spacmit_dwmac *dwmac,
> +					    struct stmmac_resources *stmmac_res)
> +{
> +	unsigned int mask = CTRL_WAKE_IRQ_EN;
> +	unsigned int val = stmmac_res->wol_irq >= 0 ? CTRL_WAKE_IRQ_EN : 0;

This looks like the last thing I can spot that needs to be addressed.
netdev wants to see "reverse christmas tree" local variable
declarations.

Please reverse the order of these two declarations to achieve that.

With that fixed:

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Thanks!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

On Mon, Mar 09, 2026 at 11:57:51AM +0000, Russell King (Oracle) wrote:
> On Mon, Mar 09, 2026 at 08:42:44AM +0800, Inochi Amaoto wrote:
> > +static int spacemit_dwmac_update_irq_config(struct spacmit_dwmac *dwmac,
> > +					    struct stmmac_resources *stmmac_res)
> > +{
> > +	unsigned int mask = CTRL_WAKE_IRQ_EN;
> > +	unsigned int val = stmmac_res->wol_irq >= 0 ? CTRL_WAKE_IRQ_EN : 0;
> 
> This looks like the last thing I can spot that needs to be addressed.
> netdev wants to see "reverse christmas tree" local variable
> declarations.
> 
> Please reverse the order of these two declarations to achieve that.
> 
> With that fixed:
> 
> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> 
> Thanks!
> 

Great, after some lookup, I find the variables in function 
spacemit_set_phy_intf_sel() are also needed to reversed.
I will also fix this in the next version.

Regards,
Inochi