[net-next PATCH v12 10/13] net: mdio: Add Airoha AN8855 Switch MDIO Passtrough

[Christian Marangi <ansuelsmth@gmail.com>]

Add Airoha AN8855 Switch driver to register a MDIO passtrough as switch
address is shared with the internal PHYs and require additional page
handling.

This requires the upper Switch MFD to be probed and init to actually
work.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 MAINTAINERS                    |  1 +
 drivers/net/mdio/Kconfig       | 10 +++++++
 drivers/net/mdio/Makefile      |  1 +
 drivers/net/mdio/mdio-an8855.c | 48 ++++++++++++++++++++++++++++++++++
 4 files changed, 60 insertions(+)
 create mode 100644 drivers/net/mdio/mdio-an8855.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5844addbda2b..8c83c446a69d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -731,6 +731,7 @@ F:	Documentation/devicetree/bindings/net/airoha,an8855-phy.yaml
 F:	Documentation/devicetree/bindings/net/dsa/airoha,an8855-switch.yaml
 F:	Documentation/devicetree/bindings/nvmem/airoha,an8855-efuse.yaml
 F:	drivers/mfd/airoha-an8855.c
+F:	drivers/net/mdio/mdio-an8855.c
 
 AIROHA ETHERNET DRIVER
 M:	Lorenzo Bianconi <lorenzo@kernel.org>
diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
index 4a7a303be2f7..e31a37064934 100644
--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -61,6 +61,16 @@ config MDIO_XGENE
 	  This module provides a driver for the MDIO busses found in the
 	  APM X-Gene SoC's.
 
+config MDIO_AN8855
+	tristate "Airoha AN8855 Switch MDIO bus controller"
+	depends on MFD_AIROHA_AN8855
+	depends on OF_MDIO
+	select MDIO_REGMAP
+	help
+	  This module provides a driver for the Airoha AN8855 Switch
+	  that requires a MDIO passtrough as switch address is shared
+	  with the internal PHYs and requires additional page handling.
+
 config MDIO_ASPEED
 	tristate "ASPEED MDIO bus controller"
 	depends on ARCH_ASPEED || COMPILE_TEST
diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
index 1015f0db4531..546c4e55b475 100644
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_ACPI_MDIO)		+= acpi_mdio.o
 obj-$(CONFIG_FWNODE_MDIO)	+= fwnode_mdio.o
 obj-$(CONFIG_OF_MDIO)		+= of_mdio.o
 
+obj-$(CONFIG_MDIO_AN8855)		+= mdio-an8855.o
 obj-$(CONFIG_MDIO_ASPEED)		+= mdio-aspeed.o
 obj-$(CONFIG_MDIO_BCM_IPROC)		+= mdio-bcm-iproc.o
 obj-$(CONFIG_MDIO_BCM_UNIMAC)		+= mdio-bcm-unimac.o
diff --git a/drivers/net/mdio/mdio-an8855.c b/drivers/net/mdio/mdio-an8855.c
new file mode 100644
index 000000000000..d45f71c4b0b1
--- /dev/null
+++ b/drivers/net/mdio/mdio-an8855.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * MDIO passthrough driver for Airoha AN8855 Switch
+ */
+
+#include <linux/mdio/mdio-regmap.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+static int an8855_mdio_probe(struct platform_device *pdev)
+{
+	struct mdio_regmap_config mrc = { };
+	struct device *dev = &pdev->dev;
+	struct mii_bus *bus;
+
+	mrc.regmap = dev_get_regmap(dev->parent, "phy");
+	mrc.parent = dev;
+	mrc.valid_addr_mask = GENMASK(31, 0);
+	mrc.autoscan = true;
+	mrc.np = dev->of_node;
+	snprintf(mrc.name, MII_BUS_ID_SIZE, KBUILD_MODNAME);
+
+	bus = devm_mdio_regmap_register(dev, &mrc);
+	if (IS_ERR(bus))
+		return dev_err_probe(dev, PTR_ERR(bus), "failed to register MDIO bus\n");
+
+	return 0;
+}
+
+static const struct of_device_id an8855_mdio_of_match[] = {
+	{ .compatible = "airoha,an8855-mdio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, an8855_mdio_of_match);
+
+static struct platform_driver an8855_mdio_driver = {
+	.probe	= an8855_mdio_probe,
+	.driver = {
+		.name = "an8855-mdio",
+		.of_match_table = an8855_mdio_of_match,
+	},
+};
+module_platform_driver(an8855_mdio_driver);
+
+MODULE_AUTHOR("Christian Marangi <ansuelsmth@gmail.com>");
+MODULE_DESCRIPTION("Driver for AN8855 MDIO passthrough");
+MODULE_LICENSE("GPL");
-- 
2.48.1