Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt b/Documentation/devicetree/bindings/net/mdio-mux.txt
new file mode 100644
index 0000000..a908312
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/mdio-mux.txt

@@ -0,0 +1,132 @@
+Common MDIO bus multiplexer/switch properties.
+
+An MDIO bus multiplexer/switch will have several child busses that are
+numbered uniquely in a device dependent manner.  The nodes for an MDIO
+bus multiplexer/switch will have one child node for each child bus.
+
+Required properties:
+- parent-bus : phandle to the parent MDIO bus.

+
+Optional properties:
+- Other properties specific to the multiplexer/switch hardware.
+
+Required properties for child nodes:
+- #address-cells = <1>;
+- #size-cells = <0>;
+- cell-index : The sub-bus number.

+
+
+Example :

diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
new file mode 100644
index 0000000..f9c5826
--- /dev/null
+++ b/drivers/net/phy/mdio-mux.c

@@ -0,0 +1,182 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011 Cavium Networks
+ */
+
+#include <linux/platform_device.h>
+#include <linux/of_mdio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/gfp.h>
+#include <linux/phy.h>
+#include <linux/mdio-mux.h>
+
+#define DRV_VERSION "1.0"
+#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
+
+struct mdio_mux_parent_bus {
+	struct mii_bus *mii_bus;
+	int current_child;
+	int parent_id;
+	void *switch_data;
+	int (*switch_fn)(int current_child, int desired_child, void *data);
+};
+
+struct mdio_mux_child_bus {
+	struct mii_bus *mii_bus;
+	struct mdio_mux_parent_bus *parent;
+	int bus_number;
+	int phy_irq[PHY_MAX_ADDR];
+};
+
+/*
+ * The parent bus' lock is used to order access to the switch_fn.
+ */
+static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
+{
+	struct mdio_mux_child_bus *cb = bus->priv;
+	struct mdio_mux_parent_bus *pb = cb->parent;
+	int r;
+
+	mutex_lock(&pb->mii_bus->mdio_lock);
+	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
+	if (r)
+		goto out;
+
+	pb->current_child = cb->bus_number;
+
+	r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
+out:
+	mutex_unlock(&pb->mii_bus->mdio_lock);
+
+	return r;
+}
+
+/*
+ * The parent bus' lock is used to order access to the switch_fn.
+ */
+static int mdio_mux_write(struct mii_bus *bus, int phy_id,
+			  int regnum, u16 val)
+{
+	struct mdio_mux_child_bus *cb = bus->priv;
+	struct mdio_mux_parent_bus *pb = cb->parent;
+
+	int r;
+
+	mutex_lock(&pb->mii_bus->mdio_lock);
+	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
+	if (r)
+		goto out;
+
+	pb->current_child = cb->bus_number;
+
+	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
+out:
+	mutex_unlock(&pb->mii_bus->mdio_lock);
+
+	return r;
+}
+
+static int parent_count;
+
+int mdio_mux_probe(struct platform_device *pdev,
+		   int (*switch_fn)(int cur, int desired, void *data),
+		   void *data)
+{
+	struct device_node *parent_bus_node;
+	struct device_node *child_bus_node;
+	int r, n, ret_val;
+	struct mii_bus *parent_bus;
+	struct mdio_mux_parent_bus *pb;
+	struct mdio_mux_child_bus *cb;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	parent_bus_node = of_parse_phandle(pdev->dev.of_node, "parent-bus", 0);
+
+	if (!parent_bus_node)
+		return -ENODEV;
+
+	parent_bus = of_mdio_find_bus(parent_bus_node);

+
+	pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
+	if (pb == NULL) {
+		ret_val = -ENOMEM;
+		goto err_parent_bus;
+	}
+
+	pb->switch_data = data;
+	pb->switch_fn = switch_fn;
+	pb->current_child = -1;
+	pb->parent_id = parent_count++;
+	pb->mii_bus = parent_bus;
+
+	n = 0;
+	for_each_child_of_node(pdev->dev.of_node, child_bus_node) {
+		u32 v;
+
+		r = of_property_read_u32(child_bus_node, "cell-index", &v);
+		if (r == 0) {
+			cb = devm_kzalloc(&pdev->dev, sizeof(*cb), GFP_KERNEL);
+			if (cb == NULL)
+				break;
+			cb->bus_number = v;
+			cb->parent = pb;
+			cb->mii_bus = mdiobus_alloc();
+			cb->mii_bus->priv = cb;
+
+			cb->mii_bus->irq = cb->phy_irq;
+			cb->mii_bus->name = "mdio_mux";
+			snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
+				 pb->parent_id, v);
+			cb->mii_bus->parent = &pdev->dev;
+			cb->mii_bus->read = mdio_mux_read;
+			cb->mii_bus->write = mdio_mux_write;
+			r = of_mdiobus_register(cb->mii_bus, child_bus_node);
+			if (r) {
+				of_node_put(child_bus_node);
+				devm_kfree(&pdev->dev, cb);
+			} else {
+				n++;
+			}
+
+		} else {
+			of_node_put(child_bus_node);
+		}
+	}
+	if (n) {
+		dev_info(&pdev->dev, "Version " DRV_VERSION "\n");
+		return 0;
+	}
+	ret_val = -ENOMEM;
+	devm_kfree(&pdev->dev, pb);
+err_parent_bus:
+	of_node_put(parent_bus_node);
+	return ret_val;
+}
+EXPORT_SYMBOL(mdio_mux_probe);
+
+static int __devexit mdio_mux_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static int __init mdio_mux_mod_init(void)
+{
+	return 0;
+}
+module_init(mdio_mux_mod_init);
+
+static void __exit mdio_mux_mod_exit(void)
+{
+}
+module_exit(mdio_mux_mod_exit);
+
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("David Daney");
+MODULE_LICENSE("GPL");