[2/2] net: mdio: Add BCM6368 MDIO mux bus controller

diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
index a10cc460d7cf..d06e06f5e31a 100644
--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -200,6 +200,17 @@  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_BCM6368
+	tristate "Broadcom BCM6368 MDIO bus multiplexers"
+	depends on OF && OF_MDIO && (BMIPS_GENERIC || COMPILE_TEST)
+	select MDIO_BUS_MUX
+	default BMIPS_GENERIC
+	help
+	  This module provides a driver for MDIO bus multiplexers found in
+	  BCM6368 based Broadcom SoCs. This multiplexer connects one of several
+	  child MDIO bus to a parent bus. Buses could be internal as well as
+	  external and selection logic lies inside the same multiplexer.
+
 config MDIO_BUS_MUX_BCM_IPROC
 	tristate "Broadcom iProc based MDIO bus multiplexers"
 	depends on OF && OF_MDIO && (ARCH_BCM_IPROC || COMPILE_TEST)
diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
index 5c498dde463f..c3ec0ef989df 100644
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -22,6 +22,7 @@  obj-$(CONFIG_MDIO_THUNDER)		+= mdio-thunder.o
 obj-$(CONFIG_MDIO_XGENE)		+= mdio-xgene.o
 
 obj-$(CONFIG_MDIO_BUS_MUX)		+= mdio-mux.o
+obj-$(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
diff --git a/drivers/net/mdio/mdio-mux-bcm6368.c b/drivers/net/mdio/mdio-mux-bcm6368.c
new file mode 100644
index 000000000000..79ab2e2af5b9
--- /dev/null
+++ b/drivers/net/mdio/mdio-mux-bcm6368.c
@@ -0,0 +1,179 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Broadcom BCM6368 mdiomux bus controller driver
+ *
+ * Copyright (C) 2021 Álvaro Fernández Rojas <noltari@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mdio-mux.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+
+#define MDIOC_REG		0x0
+#define MDIOC_EXT_MASK		BIT(16)
+#define MDIOC_REG_SHIFT		20
+#define MDIOC_PHYID_SHIFT	25
+#define MDIOC_RD_MASK		BIT(30)
+#define MDIOC_WR_MASK		BIT(31)
+
+#define MDIOD_REG		0x4
+
+struct bcm6368_mdiomux_desc {
+	void *mux_handle;
+	void __iomem *base;
+	struct device *dev;
+	struct mii_bus *mii_bus;
+	int ext_phy;
+};
+
+static int bcm6368_mdiomux_read(struct mii_bus *bus, int phy_id, int loc)
+{
+	struct bcm6368_mdiomux_desc *md = bus->priv;
+	uint32_t reg;
+	int ret;
+
+	__raw_writel(0, md->base + MDIOC_REG);
+
+	reg = MDIOC_RD_MASK |
+	      (phy_id << MDIOC_PHYID_SHIFT) |
+	      (loc << MDIOC_REG_SHIFT);
+	if (md->ext_phy)
+		reg |= MDIOC_EXT_MASK;
+
+	__raw_writel(reg, md->base + MDIOC_REG);
+	udelay(50);
+	ret = __raw_readw(md->base + MDIOD_REG);
+
+	return ret;
+}
+
+static int bcm6368_mdiomux_write(struct mii_bus *bus, int phy_id, int loc,
+				 uint16_t val)
+{
+	struct bcm6368_mdiomux_desc *md = bus->priv;
+	uint32_t reg;
+
+	__raw_writel(0, md->base + MDIOC_REG);
+
+	reg = MDIOC_WR_MASK |
+	      (phy_id << MDIOC_PHYID_SHIFT) |
+	      (loc << MDIOC_REG_SHIFT);
+	if (md->ext_phy)
+		reg |= MDIOC_EXT_MASK;
+	reg |= val;
+
+	__raw_writel(reg, md->base + MDIOC_REG);
+	udelay(50);
+
+	return 0;
+}
+
+static int bcm6368_mdiomux_switch_fn(int current_child, int desired_child,
+				     void *data)
+{
+	struct bcm6368_mdiomux_desc *md = data;
+
+	md->ext_phy = desired_child;
+
+	return 0;
+}
+
+static int bcm6368_mdiomux_probe(struct platform_device *pdev)
+{
+	struct bcm6368_mdiomux_desc *md;
+	struct mii_bus *bus;
+	struct resource *res;
+	int rc;
+
+	md = devm_kzalloc(&pdev->dev, sizeof(*md), GFP_KERNEL);
+	if (!md)
+		return -ENOMEM;
+	md->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	/* Just ioremap, as this MDIO block is usually integrated into an
+	 * Ethernet MAC controller register range
+	 */
+	md->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!md->base) {
+		dev_err(&pdev->dev, "failed to ioremap register\n");
+		return -ENOMEM;
+	}
+
+	md->mii_bus = devm_mdiobus_alloc(&pdev->dev);
+	if (!md->mii_bus) {
+		dev_err(&pdev->dev, "mdiomux bus alloc failed\n");
+		return ENOMEM;
+	}
+
+	bus = md->mii_bus;
+	bus->priv = md;
+	bus->name = "BCM6368 MDIO mux bus";
+	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);
+	bus->parent = &pdev->dev;
+	bus->read = bcm6368_mdiomux_read;
+	bus->write = bcm6368_mdiomux_write;
+	bus->phy_mask = 0x3f;
+	bus->dev.of_node = pdev->dev.of_node;
+
+	rc = mdiobus_register(bus);
+	if (rc) {
+		dev_err(&pdev->dev, "mdiomux registration failed\n");
+		return rc;
+	}
+
+	platform_set_drvdata(pdev, md);
+
+	rc = mdio_mux_init(md->dev, md->dev->of_node,
+			   bcm6368_mdiomux_switch_fn, &md->mux_handle, md,
+			   md->mii_bus);
+	if (rc) {
+		dev_info(md->dev, "mdiomux initialization failed\n");
+		goto out_register;
+	}
+
+	dev_info(&pdev->dev, "Broadcom BCM6368 MDIO mux bus\n");
+
+	return 0;
+
+out_register:
+	mdiobus_unregister(bus);
+	return rc;
+}
+
+static int bcm6368_mdiomux_remove(struct platform_device *pdev)
+{
+	struct bcm6368_mdiomux_desc *md = platform_get_drvdata(pdev);
+
+	mdio_mux_uninit(md->mux_handle);
+	mdiobus_unregister(md->mii_bus);
+
+	return 0;
+}
+
+static const struct of_device_id bcm6368_mdiomux_ids[] = {
+	{ .compatible = "brcm,bcm6368-mdio-mux", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, bcm6368_mdiomux_ids);
+
+static struct platform_driver bcm6368_mdiomux_driver = {
+	.driver = {
+		.name = "bcm6368-mdio-mux",
+		.of_match_table = bcm6368_mdiomux_ids,
+	},
+	.probe	= bcm6368_mdiomux_probe,
+	.remove	= bcm6368_mdiomux_remove,
+};
+module_platform_driver(bcm6368_mdiomux_driver);