1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2011, 2012 Cavium, Inc.
4 */
5
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>
12
13#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
14
15struct mdio_mux_child_bus;
16
17struct mdio_mux_parent_bus {
18	struct mii_bus *mii_bus;
19	int current_child;
20	int parent_id;
21	void *switch_data;
22	int (*switch_fn)(int current_child, int desired_child, void *data);
23
24	/* List of our children linked through their next fields. */
25	struct mdio_mux_child_bus *children;
26};
27
28struct mdio_mux_child_bus {
29	struct mii_bus *mii_bus;
30	struct mdio_mux_parent_bus *parent;
31	struct mdio_mux_child_bus *next;
32	int bus_number;
33};
34
35/*
36 * The parent bus' lock is used to order access to the switch_fn.
37 */
38static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
39{
40	struct mdio_mux_child_bus *cb = bus->priv;
41	struct mdio_mux_parent_bus *pb = cb->parent;
42	int r;
43
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);
46	if (r)
47		goto out;
48
49	pb->current_child = cb->bus_number;
50
51	r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
52out:
53	mutex_unlock(&pb->mii_bus->mdio_lock);
54
55	return r;
56}
57
58/*
59 * The parent bus' lock is used to order access to the switch_fn.
60 */
61static int mdio_mux_write(struct mii_bus *bus, int phy_id,
62			  int regnum, u16 val)
63{
64	struct mdio_mux_child_bus *cb = bus->priv;
65	struct mdio_mux_parent_bus *pb = cb->parent;
66
67	int r;
68
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);
71	if (r)
72		goto out;
73
74	pb->current_child = cb->bus_number;
75
76	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
77out:
78	mutex_unlock(&pb->mii_bus->mdio_lock);
79
80	return r;
81}
82
83static int parent_count;
84
85static void mdio_mux_uninit_children(struct mdio_mux_parent_bus *pb)
86{
87	struct mdio_mux_child_bus *cb = pb->children;
88
89	while (cb) {
90		mdiobus_unregister(cb->mii_bus);
91		mdiobus_free(cb->mii_bus);
92		cb = cb->next;
93	}
94}
95
96int mdio_mux_init(struct device *dev,
97		  struct device_node *mux_node,
98		  int (*switch_fn)(int cur, int desired, void *data),
99		  void **mux_handle,
100		  void *data,
101		  struct mii_bus *mux_bus)
102{
103	struct device_node *parent_bus_node;
104	struct device_node *child_bus_node;
105	int r, ret_val;
106	struct mii_bus *parent_bus;
107	struct mdio_mux_parent_bus *pb;
108	struct mdio_mux_child_bus *cb;
109
110	if (!mux_node)
111		return -ENODEV;
112
113	if (!mux_bus) {
114		parent_bus_node = of_parse_phandle(mux_node,
115						   "mdio-parent-bus", 0);
116
117		if (!parent_bus_node)
118			return -ENODEV;
119
120		parent_bus = of_mdio_find_bus(parent_bus_node);
121		if (!parent_bus) {
122			ret_val = -EPROBE_DEFER;
123			goto err_parent_bus;
124		}
125	} else {
126		parent_bus_node = NULL;
127		parent_bus = mux_bus;
128		get_device(&parent_bus->dev);
129	}
130
131	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
132	if (!pb) {
133		ret_val = -ENOMEM;
134		goto err_pb_kz;
135	}
136
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;
142
143	ret_val = -ENODEV;
144	for_each_available_child_of_node(mux_node, child_bus_node) {
145		int v;
146
147		r = of_property_read_u32(child_bus_node, "reg", &v);
148		if (r) {
149			dev_err(dev,
150				"Error: Failed to find reg for child %pOF\n",
151				child_bus_node);
152			continue;
153		}
154
155		cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
156		if (!cb) {
157			ret_val = -ENOMEM;
158			goto err_loop;
159		}
160		cb->bus_number = v;
161		cb->parent = pb;
162
163		cb->mii_bus = mdiobus_alloc();
164		if (!cb->mii_bus) {
165			ret_val = -ENOMEM;
166			goto err_loop;
167		}
168		cb->mii_bus->priv = cb;
169
170		cb->mii_bus->name = "mdio_mux";
171		snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
172			 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);
177		if (r) {
178			mdiobus_free(cb->mii_bus);
179			if (r == -EPROBE_DEFER) {
180				ret_val = r;
181				goto err_loop;
182			}
183			devm_kfree(dev, cb);
184			dev_err(dev,
185				"Error: Failed to register MDIO bus for child %pOF\n",
186				child_bus_node);
187		} else {
188			cb->next = pb->children;
189			pb->children = cb;
190		}
191	}
192	if (pb->children) {
193		*mux_handle = pb;
194		return 0;
195	}
196
197	dev_err(dev, "Error: No acceptable child buses found\n");
198	devm_kfree(dev, pb);
199
200err_loop:
201	mdio_mux_uninit_children(pb);
202	of_node_put(child_bus_node);
203err_pb_kz:
204	put_device(&parent_bus->dev);
205err_parent_bus:
206	of_node_put(parent_bus_node);
207	return ret_val;
208}
209EXPORT_SYMBOL_GPL(mdio_mux_init);
210
211void mdio_mux_uninit(void *mux_handle)
212{
213	struct mdio_mux_parent_bus *pb = mux_handle;
214
215	mdio_mux_uninit_children(pb);
216	put_device(&pb->mii_bus->dev);
217}
218EXPORT_SYMBOL_GPL(mdio_mux_uninit);
219
220MODULE_DESCRIPTION(DRV_DESCRIPTION);
221MODULE_AUTHOR("David Daney");
222MODULE_LICENSE("GPL v2");
223