[PATCH net-next 2/2] net: mdio-mux: Add MDIO mux driver for Sophgo CV1800 SoCs

[Inochi Amaoto]

Add device driver for the mux driver for Sophgo CV18XX/SG200X
series SoCs.

Signed-off-by: Inochi Amaoto <inochiama at gmail.com>
---
 drivers/net/mdio/Kconfig            |  10 +++
 drivers/net/mdio/Makefile           |   1 +
 drivers/net/mdio/mdio-mux-cv1800b.c | 119 ++++++++++++++++++++++++++++
 3 files changed, 130 insertions(+)
 create mode 100644 drivers/net/mdio/mdio-mux-cv1800b.c

diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
index 7db40aaa079d..fe553016b77d 100644
--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -278,5 +278,15 @@ config MDIO_BUS_MUX_MMIOREG
 
 	  Currently, only 8/16/32 bits registers are supported.
 
+config MDIO_BUS_MUX_SOPHGO_CV1800B
+	tristate "Sophgo CV1800 MDIO multiplexer driver"
+	depends on ARCH_SOPHGO || COMPILE_TEST
+	depends on OF_MDIO && HAS_IOMEM
+	select MDIO_BUS_MUX
+	default m if ARCH_SOPHGO
+	help
+	  This module provides a driver for the MDIO multiplexer/glue of
+	  the Sophgo CV1800 series SoC. The multiplexer connects either
+	  the external or the internal MDIO bus to the parent bus.
 
 endif
diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
index c23778e73890..a67be2abc343 100644
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_MDIO_BUS_MUX_MESON_G12A)	+= mdio-mux-meson-g12a.o
 obj-$(CONFIG_MDIO_BUS_MUX_MESON_GXL)	+= mdio-mux-meson-gxl.o
 obj-$(CONFIG_MDIO_BUS_MUX_MMIOREG) 	+= mdio-mux-mmioreg.o
 obj-$(CONFIG_MDIO_BUS_MUX_MULTIPLEXER) 	+= mdio-mux-multiplexer.o
+obj-$(CONFIG_MDIO_BUS_MUX_SOPHGO_CV1800B) += mdio-mux-cv1800b.o
diff --git a/drivers/net/mdio/mdio-mux-cv1800b.c b/drivers/net/mdio/mdio-mux-cv1800b.c
new file mode 100644
index 000000000000..6c69e83c3dcd
--- /dev/null
+++ b/drivers/net/mdio/mdio-mux-cv1800b.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sophgo CV1800 MDIO multiplexer driver
+ *
+ * Copyright (C) 2025 Inochi Amaoto <inochiama at gmail.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/mdio-mux.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define EPHY_PAGE_SELECT		0x07c
+#define EPHY_CTRL			0x800
+#define EPHY_REG_SELECT			0x804
+
+#define EPHY_PAGE_SELECT_SRC		GENMASK(12, 8)
+
+#define EPHY_CTRL_ANALOG_SHUTDOWN	BIT(0)
+#define EPHY_CTRL_USE_EXTPHY		BIT(7)
+#define EPHY_CTRL_PHYMODE		BIT(8)
+#define EPHY_CTRL_PHYMODE_SMI_RMII	1
+#define EPHY_CTRL_EXTPHY_ID		GENMASK(15, 11)
+
+#define EPHY_REG_SELECT_MDIO		0
+#define EPHY_REG_SELECT_APB		1
+
+#define CV1800B_MDIO_INTERNAL_ID	1
+#define CV1800B_MDIO_EXTERNAL_ID	0
+
+struct cv1800b_mdio_mux {
+	void __iomem *regs;
+	void *mux_handle;
+};
+
+static int cv1800b_enable_mdio(struct cv1800b_mdio_mux *mdmux, bool internal_phy)
+{
+	u32 val;
+
+	val = readl(mdmux->regs + EPHY_CTRL);
+
+	if (internal_phy)
+		val &= ~EPHY_CTRL_USE_EXTPHY;
+	else
+		val |= EPHY_CTRL_USE_EXTPHY;
+
+	writel(val, mdmux->regs + EPHY_CTRL);
+
+	writel(EPHY_REG_SELECT_MDIO, mdmux->regs + EPHY_REG_SELECT);
+
+	return 0;
+}
+
+static int cv1800b_mdio_switch_fn(int current_child, int desired_child,
+				  void *data)
+{
+	struct cv1800b_mdio_mux *mdmux = dev_get_drvdata(data);
+
+	if (current_child == desired_child)
+		return 0;
+
+	switch (desired_child) {
+	case CV1800B_MDIO_EXTERNAL_ID:
+		return cv1800b_enable_mdio(mdmux, false);
+	case CV1800B_MDIO_INTERNAL_ID:
+		return cv1800b_enable_mdio(mdmux, true);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int cv1800b_mdio_mux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cv1800b_mdio_mux *mdmux;
+
+	mdmux = devm_kzalloc(dev, sizeof(*mdmux), GFP_KERNEL);
+	if (!mdmux)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, mdmux);
+
+	mdmux->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(mdmux->regs))
+		return PTR_ERR(mdmux->regs);
+
+	return mdio_mux_init(dev, dev->of_node, cv1800b_mdio_switch_fn,
+			     &mdmux->mux_handle, dev, NULL);
+}
+
+static void cv1800b_mdio_mux_remove(struct platform_device *pdev)
+{
+	struct cv1800b_mdio_mux *mdmux = platform_get_drvdata(pdev);
+
+	mdio_mux_uninit(mdmux->mux_handle);
+}
+
+static const struct of_device_id cv1800b_mdio_mux_match[] = {
+	{ .compatible = "sophgo,cv1800b-mdio-mux", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, cv1800b_mdio_mux_match);
+
+static struct platform_driver cv1800b_mdio_mux_driver = {
+	.probe		= cv1800b_mdio_mux_probe,
+	.remove		= cv1800b_mdio_mux_remove,
+	.driver		= {
+		.name	= "cv1800b-mdio-mux",
+		.of_match_table = cv1800b_mdio_mux_match,
+	},
+};
+module_platform_driver(cv1800b_mdio_mux_driver);
+
+MODULE_DESCRIPTION("Sophgo CV1800 MDIO multiplexer driver");
+MODULE_AUTHOR("Inochi Amaoto <inochiama at gmail.com>");
+MODULE_LICENSE("GPL");
-- 
2.49.0