1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2011, 2012 Cavium, Inc.
6 #include <linux/device.h>
7 #include <linux/mdio-mux.h>
8 #include <linux/module.h>
9 #include <linux/of_mdio.h>
10 #include <linux/phy.h>
11 #include <linux/platform_device.h>
13 #define DRV_DESCRIPTION "MDIO bus multiplexer driver"
15 struct mdio_mux_child_bus;
17 struct mdio_mux_parent_bus {
18 struct mii_bus *mii_bus;
22 int (*switch_fn)(int current_child, int desired_child, void *data);
24 /* List of our children linked through their next fields. */
25 struct mdio_mux_child_bus *children;
28 struct mdio_mux_child_bus {
29 struct mii_bus *mii_bus;
30 struct mdio_mux_parent_bus *parent;
31 struct mdio_mux_child_bus *next;
36 * The parent bus' lock is used to order access to the switch_fn.
38 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
40 struct mdio_mux_child_bus *cb = bus->priv;
41 struct mdio_mux_parent_bus *pb = cb->parent;
44 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
45 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
49 pb->current_child = cb->bus_number;
51 r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
53 mutex_unlock(&pb->mii_bus->mdio_lock);
59 * The parent bus' lock is used to order access to the switch_fn.
61 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
64 struct mdio_mux_child_bus *cb = bus->priv;
65 struct mdio_mux_parent_bus *pb = cb->parent;
69 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
70 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
74 pb->current_child = cb->bus_number;
76 r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
78 mutex_unlock(&pb->mii_bus->mdio_lock);
83 static int parent_count;
85 static void mdio_mux_uninit_children(struct mdio_mux_parent_bus *pb)
87 struct mdio_mux_child_bus *cb = pb->children;
90 mdiobus_unregister(cb->mii_bus);
91 mdiobus_free(cb->mii_bus);
96 int mdio_mux_init(struct device *dev,
97 struct device_node *mux_node,
98 int (*switch_fn)(int cur, int desired, void *data),
101 struct mii_bus *mux_bus)
103 struct device_node *parent_bus_node;
104 struct device_node *child_bus_node;
106 struct mii_bus *parent_bus;
107 struct mdio_mux_parent_bus *pb;
108 struct mdio_mux_child_bus *cb;
114 parent_bus_node = of_parse_phandle(mux_node,
115 "mdio-parent-bus", 0);
117 if (!parent_bus_node)
120 parent_bus = of_mdio_find_bus(parent_bus_node);
122 ret_val = -EPROBE_DEFER;
126 parent_bus_node = NULL;
127 parent_bus = mux_bus;
128 get_device(&parent_bus->dev);
131 pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
137 pb->switch_data = data;
138 pb->switch_fn = switch_fn;
139 pb->current_child = -1;
140 pb->parent_id = parent_count++;
141 pb->mii_bus = parent_bus;
144 for_each_available_child_of_node(mux_node, child_bus_node) {
147 r = of_property_read_u32(child_bus_node, "reg", &v);
150 "Error: Failed to find reg for child %pOF\n",
155 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
163 cb->mii_bus = mdiobus_alloc();
168 cb->mii_bus->priv = cb;
170 cb->mii_bus->name = "mdio_mux";
171 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%s-%x.%x",
172 cb->mii_bus->name, pb->parent_id, v);
173 cb->mii_bus->parent = dev;
174 cb->mii_bus->read = mdio_mux_read;
175 cb->mii_bus->write = mdio_mux_write;
176 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
178 mdiobus_free(cb->mii_bus);
179 if (r == -EPROBE_DEFER) {
185 "Error: Failed to register MDIO bus for child %pOF\n",
188 cb->next = pb->children;
197 dev_err(dev, "Error: No acceptable child buses found\n");
200 mdio_mux_uninit_children(pb);
201 of_node_put(child_bus_node);
203 put_device(&parent_bus->dev);
205 of_node_put(parent_bus_node);
208 EXPORT_SYMBOL_GPL(mdio_mux_init);
210 void mdio_mux_uninit(void *mux_handle)
212 struct mdio_mux_parent_bus *pb = mux_handle;
214 mdio_mux_uninit_children(pb);
215 put_device(&pb->mii_bus->dev);
217 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
219 MODULE_DESCRIPTION(DRV_DESCRIPTION);
220 MODULE_AUTHOR("David Daney");
221 MODULE_LICENSE("GPL v2");