Merge branch 'net-mdio-add-amlogic-gxl-mdio-mux-support'

Jerome Brunet says:

====================
net: mdio: add amlogic gxl mdio mux support

Add support for the MDIO multiplexer found in the Amlogic GXL SoC family.
This multiplexer allows to choose between the external (SoC pins) MDIO bus,
or the internal one leading to the integrated 10/100M PHY.

This multiplexer has been handled with the mdio-mux-mmioreg generic driver
so far. When it was added, it was thought the logic was handled by a
single register.

It turns out more than a single register need to be properly set.
As long as the device is using the Amlogic vendor bootloader, or upstream
u-boot with net support, it is working fine since the kernel is inheriting
the bootloader settings. Without net support in the bootloader, this glue
comes unset in the kernel and only the external path may operate properly.

With this driver (and the associated change in
arch/arm64/boot/dts/amlogic/meson-gxl.dtsi), the kernel no longer relies
on the bootloader to set things up, fixing the problem.
====================

Link: https://lore.kernel.org/r/20230130151616.375168-1-jbrunet@baylibre.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 240 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/net/amlogic,gxl-mdio-mux.yaml b/Documentation/devicetree/bindings/net/amlogic,gxl-mdio-mux.yaml
new file mode 100644
index 000000000000..27ae004dbea0
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/amlogic,gxl-mdio-mux.yaml
@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/amlogic,gxl-mdio-mux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Amlogic GXL MDIO bus multiplexer
+
+maintainers:
+  - Jerome Brunet <jbrunet@baylibre.com>
+
+description:
+  This is a special case of a MDIO bus multiplexer. It allows to choose between
+  the internal mdio bus leading to the embedded 10/100 PHY or the external
+  MDIO bus on the Amlogic GXL SoC family.
+
+allOf:
+  - $ref: mdio-mux.yaml#
+
+properties:
+  compatible:
+    const: amlogic,gxl-mdio-mux
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: ref
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    eth_phy_mux: mdio@558 {
+      compatible = "amlogic,gxl-mdio-mux";
+      reg = <0x558 0xc>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+      clocks = <&refclk>;
+      clock-names = "ref";
+      mdio-parent-bus = <&mdio0>;
+
+      external_mdio: mdio@0 {
+        reg = <0x0>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+      };
+
+      internal_mdio: mdio@1 {
+        reg = <0x1>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+      };
+    };
diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
index bfa16826a6e1..90309980686e 100644
--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -215,6 +215,17 @@ config MDIO_BUS_MUX_MESON_G12A
 	  the amlogic g12a SoC. The multiplexers connects either the external
 	  or the internal MDIO bus to the parent bus.
 
+config MDIO_BUS_MUX_MESON_GXL
+	tristate "Amlogic GXL based MDIO bus multiplexer"
+	depends on ARCH_MESON || COMPILE_TEST
+	depends on OF_MDIO && HAS_IOMEM && COMMON_CLK
+	select MDIO_BUS_MUX
+	default m if ARCH_MESON
+	help
+	  This module provides a driver for the MDIO multiplexer/glue of
+	  the amlogic GXL SoC. The multiplexer connects either the external
+	  or the internal MDIO bus to the parent bus.
+
 config MDIO_BUS_MUX_BCM6368
 	tristate "Broadcom BCM6368 MDIO bus multiplexers"
 	depends on OF && OF_MDIO && (BMIPS_GENERIC || COMPILE_TEST)
diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
index 15f8dc4042ce..7d4cb4c11e4e 100644
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -28,5 +28,6 @@ obj-$(CONFIG_MDIO_BUS_MUX_BCM6368)	+= mdio-mux-bcm6368.o
 obj-$(CONFIG_MDIO_BUS_MUX_BCM_IPROC)	+= mdio-mux-bcm-iproc.o
 obj-$(CONFIG_MDIO_BUS_MUX_GPIO)		+= mdio-mux-gpio.o
 obj-$(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
diff --git a/drivers/net/mdio/mdio-mux-meson-gxl.c b/drivers/net/mdio/mdio-mux-meson-gxl.c
new file mode 100644
index 000000000000..76188575ca1f
--- /dev/null
+++ b/drivers/net/mdio/mdio-mux-meson-gxl.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Baylibre, SAS.
+ * Author: Jerome Brunet <jbrunet@baylibre.com>
+ */
+
+#include <linux/bitfield.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 ETH_REG2		0x0
+#define  REG2_PHYID		GENMASK(21, 0)
+#define   EPHY_GXL_ID		0x110181
+#define  REG2_LEDACT		GENMASK(23, 22)
+#define  REG2_LEDLINK		GENMASK(25, 24)
+#define  REG2_DIV4SEL		BIT(27)
+#define  REG2_ADCBYPASS		BIT(30)
+#define  REG2_CLKINSEL		BIT(31)
+#define ETH_REG3		0x4
+#define  REG3_ENH		BIT(3)
+#define  REG3_CFGMODE		GENMASK(6, 4)
+#define  REG3_AUTOMDIX		BIT(7)
+#define  REG3_PHYADDR		GENMASK(12, 8)
+#define  REG3_PWRUPRST		BIT(21)
+#define  REG3_PWRDOWN		BIT(22)
+#define  REG3_LEDPOL		BIT(23)
+#define  REG3_PHYMDI		BIT(26)
+#define  REG3_CLKINEN		BIT(29)
+#define  REG3_PHYIP		BIT(30)
+#define  REG3_PHYEN		BIT(31)
+#define ETH_REG4		0x8
+#define  REG4_PWRUPRSTSIG	BIT(0)
+
+#define MESON_GXL_MDIO_EXTERNAL_ID 0
+#define MESON_GXL_MDIO_INTERNAL_ID 1
+
+struct gxl_mdio_mux {
+	void __iomem *regs;
+	void *mux_handle;
+};
+
+static void gxl_enable_internal_mdio(struct gxl_mdio_mux *priv)
+{
+	u32 val;
+
+	/* Setup the internal phy */
+	val = (REG3_ENH |
+	       FIELD_PREP(REG3_CFGMODE, 0x7) |
+	       REG3_AUTOMDIX |
+	       FIELD_PREP(REG3_PHYADDR, 8) |
+	       REG3_LEDPOL |
+	       REG3_PHYMDI |
+	       REG3_CLKINEN |
+	       REG3_PHYIP);
+
+	writel(REG4_PWRUPRSTSIG, priv->regs + ETH_REG4);
+	writel(val, priv->regs + ETH_REG3);
+	mdelay(10);
+
+	/* NOTE: The HW kept the phy id configurable at runtime.
+	 * The id below is arbitrary. It is the one used in the vendor code.
+	 * The only constraint is that it must match the one in
+	 * drivers/net/phy/meson-gxl.c to properly match the PHY.
+	 */
+	writel(FIELD_PREP(REG2_PHYID, EPHY_GXL_ID),
+	       priv->regs + ETH_REG2);
+
+	/* Enable the internal phy */
+	val |= REG3_PHYEN;
+	writel(val, priv->regs + ETH_REG3);
+	writel(0, priv->regs + ETH_REG4);
+
+	/* The phy needs a bit of time to power up */
+	mdelay(10);
+}
+
+static void gxl_enable_external_mdio(struct gxl_mdio_mux *priv)
+{
+	/* Reset the mdio bus mux to the external phy */
+	writel(0, priv->regs + ETH_REG3);
+}
+
+static int gxl_mdio_switch_fn(int current_child, int desired_child,
+			      void *data)
+{
+	struct gxl_mdio_mux *priv = dev_get_drvdata(data);
+
+	if (current_child == desired_child)
+		return 0;
+
+	switch (desired_child) {
+	case MESON_GXL_MDIO_EXTERNAL_ID:
+		gxl_enable_external_mdio(priv);
+		break;
+	case MESON_GXL_MDIO_INTERNAL_ID:
+		gxl_enable_internal_mdio(priv);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id gxl_mdio_mux_match[] = {
+	{ .compatible = "amlogic,gxl-mdio-mux", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, gxl_mdio_mux_match);
+
+static int gxl_mdio_mux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gxl_mdio_mux *priv;
+	struct clk *rclk;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, priv);
+
+	priv->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	rclk = devm_clk_get_enabled(dev, "ref");
+	if (IS_ERR(rclk))
+		return dev_err_probe(dev, PTR_ERR(rclk),
+				     "failed to get reference clock\n");
+
+	ret = mdio_mux_init(dev, dev->of_node, gxl_mdio_switch_fn,
+			    &priv->mux_handle, dev, NULL);
+	if (ret)
+		dev_err_probe(dev, ret, "mdio multiplexer init failed\n");
+
+	return ret;
+}
+
+static int gxl_mdio_mux_remove(struct platform_device *pdev)
+{
+	struct gxl_mdio_mux *priv = platform_get_drvdata(pdev);
+
+	mdio_mux_uninit(priv->mux_handle);
+
+	return 0;
+}
+
+static struct platform_driver gxl_mdio_mux_driver = {
+	.probe		= gxl_mdio_mux_probe,
+	.remove		= gxl_mdio_mux_remove,
+	.driver		= {
+		.name	= "gxl-mdio-mux",
+		.of_match_table = gxl_mdio_mux_match,
+	},
+};
+module_platform_driver(gxl_mdio_mux_driver);
+
+MODULE_DESCRIPTION("Amlogic GXL MDIO multiplexer driver");
+MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
+MODULE_LICENSE("GPL");