1 files changed, 58 insertions, 0 deletions
diff --git a/drivers/net/mdio/acpi_mdio.c b/drivers/net/mdio/acpi_mdio.c
new file mode 100644
index 000000000000..d77c987fda9c
--- /dev/null
+++ b/drivers/net/mdio/acpi_mdio.c
@@ -0,0 +1,58 @@
+// 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>
+#include <linux/bits.h>
+#include <linux/dev_printk.h>
+#include <linux/fwnode_mdio.h>
+#include <linux/module.h>
+#include <linux/types.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 fwnode is expected to represent
+ * an ACPI device object corresponding to the MDIO bus and its children are
+ * expected to correspond to the PHY devices on that 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);