[PATCH net-next v8 3/3] net: stmmac: Add glue layer for Spacemit K3 SoC

Inochi Amaoto
2026-03-09T00:44:02Z

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