[net-next PATCH v6 10/15] net: mdio: Add ACPI support code for mdio

[Calvin Johnson <calvin.johnson@oss.nxp.com>]

Define acpi_mdiobus_register() to Register mii_bus and create PHYs for
each ACPI child node.

Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
---

Changes in v6:
- use GENMASK() and ACPI_COMPANION_SET()
- some cleanup
- remove unwanted header inclusion

Changes in v5:
- add missing MODULE_LICENSE()
- replace fwnode_get_id() with OF and ACPI function calls

Changes in v4: None
Changes in v3: None
Changes in v2: None

 MAINTAINERS                  |  1 +
 drivers/net/mdio/Kconfig     |  7 +++++
 drivers/net/mdio/Makefile    |  1 +
 drivers/net/mdio/acpi_mdio.c | 51 ++++++++++++++++++++++++++++++++++++
 include/linux/acpi_mdio.h    | 25 ++++++++++++++++++
 5 files changed, 85 insertions(+)
 create mode 100644 drivers/net/mdio/acpi_mdio.c
 create mode 100644 include/linux/acpi_mdio.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 1a219335efe0..41d16d77b6cf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6680,6 +6680,7 @@ F:	Documentation/devicetree/bindings/net/mdio*
 F:	Documentation/devicetree/bindings/net/qca,ar803x.yaml
 F:	Documentation/networking/phy.rst
 F:	drivers/net/mdio/
+F:	drivers/net/mdio/acpi_mdio.c
 F:	drivers/net/mdio/of_mdio.c
 F:	drivers/net/pcs/
 F:	drivers/net/phy/
diff --git a/drivers/net/mdio/Kconfig b/drivers/net/mdio/Kconfig
index a10cc460d7cf..df6bb7837d6a 100644
--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -27,6 +27,13 @@ config OF_MDIO
 	help
 	  OpenFirmware MDIO bus (Ethernet PHY) accessors
 
+config ACPI_MDIO
+	def_tristate PHYLIB
+	depends on ACPI
+	depends on PHYLIB
+	help
+	  ACPI MDIO bus (Ethernet PHY) accessors
+
 if MDIO_BUS
 
 config MDIO_DEVRES
diff --git a/drivers/net/mdio/Makefile b/drivers/net/mdio/Makefile
index 5c498dde463f..2373ade8af13 100644
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -2,6 +2,7 @@
 # Makefile for Linux MDIO bus drivers
 
 obj-$(CONFIG_OF_MDIO)	+= of_mdio.o
+obj-$(CONFIG_ACPI_MDIO)	+= acpi_mdio.o
 
 obj-$(CONFIG_MDIO_ASPEED)		+= mdio-aspeed.o
 obj-$(CONFIG_MDIO_BCM_IPROC)		+= mdio-bcm-iproc.o
diff --git a/drivers/net/mdio/acpi_mdio.c b/drivers/net/mdio/acpi_mdio.c
new file mode 100644
index 000000000000..091c8272e596
--- /dev/null
+++ b/drivers/net/mdio/acpi_mdio.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ACPI helpers for the MDIO (Ethernet PHY) API
+ *
+ * This file provides helper functions for extracting PHY device information
+ * out of the ACPI ASL and using it to populate an mii_bus.
+ */
+
+#include <linux/acpi.h>
+#include <linux/acpi_mdio.h>
+
+MODULE_AUTHOR("Calvin Johnson <calvin.johnson@oss.nxp.com>");
+MODULE_LICENSE("GPL");
+
+/**
+ * acpi_mdiobus_register - Register mii_bus and create PHYs from the ACPI ASL.
+ * @mdio: pointer to mii_bus structure
+ * @fwnode: pointer to fwnode of MDIO bus.
+ *
+ * This function registers the mii_bus structure and registers a phy_device
+ * for each child node of @fwnode.
+ */
+int acpi_mdiobus_register(struct mii_bus *mdio, struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *child;
+	u32 addr;
+	int ret;
+
+	/* Mask out all PHYs from auto probing. */
+	mdio->phy_mask = GENMASK(31, 0);
+	ret = mdiobus_register(mdio);
+	if (ret)
+		return ret;
+
+	ACPI_COMPANION_SET(&mdio->dev, to_acpi_device_node(fwnode));
+
+	/* Loop over the child nodes and register a phy_device for each PHY */
+	fwnode_for_each_child_node(fwnode, child) {
+		ret = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), &addr);
+		if (ret || addr >= PHY_MAX_ADDR)
+			continue;
+
+		ret = fwnode_mdiobus_register_phy(mdio, child, addr);
+		if (ret == -ENODEV)
+			dev_err(&mdio->dev,
+				"MDIO device at address %d is missing.\n",
+				addr);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(acpi_mdiobus_register);
diff --git a/include/linux/acpi_mdio.h b/include/linux/acpi_mdio.h
new file mode 100644
index 000000000000..748d261fe2f9
--- /dev/null
+++ b/include/linux/acpi_mdio.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * ACPI helper for the MDIO (Ethernet PHY) API
+ */
+
+#ifndef __LINUX_ACPI_MDIO_H
+#define __LINUX_ACPI_MDIO_H
+
+#include <linux/phy.h>
+
+#if IS_ENABLED(CONFIG_ACPI_MDIO)
+int acpi_mdiobus_register(struct mii_bus *mdio, struct fwnode_handle *fwnode);
+#else /* CONFIG_ACPI_MDIO */
+static inline int acpi_mdiobus_register(struct mii_bus *mdio, struct fwnode_handle *fwnode)
+{
+	/*
+	 * Fall back to mdiobus_register() function to register a bus.
+	 * This way, we don't have to keep compat bits around in drivers.
+	 */
+
+	return mdiobus_register(mdio);
+}
+#endif
+
+#endif /* __LINUX_ACPI_MDIO_H */
-- 
2.17.1