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
15 struct mdio_mux_child_bus;
16
17 struct 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
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;
32 int bus_number;
33 };
34
35 /*
36 * The parent bus' lock is used to order access to the switch_fn.
37 */
mdio_mux_read(struct mii_bus * bus,int phy_id,int regnum)38 static 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);
52 out:
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 */
mdio_mux_write(struct mii_bus * bus,int phy_id,int regnum,u16 val)61 static 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);
77 out:
78 mutex_unlock(&pb->mii_bus->mdio_lock);
79
80 return r;
81 }
82
83 static int parent_count;
84
mdio_mux_init(struct device * dev,struct device_node * mux_node,int (* switch_fn)(int cur,int desired,void * data),void ** mux_handle,void * data,struct mii_bus * mux_bus)85 int mdio_mux_init(struct device *dev,
86 struct device_node *mux_node,
87 int (*switch_fn)(int cur, int desired, void *data),
88 void **mux_handle,
89 void *data,
90 struct mii_bus *mux_bus)
91 {
92 struct device_node *parent_bus_node;
93 struct device_node *child_bus_node;
94 int r, ret_val;
95 struct mii_bus *parent_bus;
96 struct mdio_mux_parent_bus *pb;
97 struct mdio_mux_child_bus *cb;
98
99 if (!mux_node)
100 return -ENODEV;
101
102 if (!mux_bus) {
103 parent_bus_node = of_parse_phandle(mux_node,
104 "mdio-parent-bus", 0);
105
106 if (!parent_bus_node)
107 return -ENODEV;
108
109 parent_bus = of_mdio_find_bus(parent_bus_node);
110 if (!parent_bus) {
111 ret_val = -EPROBE_DEFER;
112 goto err_parent_bus;
113 }
114 } else {
115 parent_bus_node = NULL;
116 parent_bus = mux_bus;
117 get_device(&parent_bus->dev);
118 }
119
120 pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
121 if (!pb) {
122 ret_val = -ENOMEM;
123 goto err_pb_kz;
124 }
125
126 pb->switch_data = data;
127 pb->switch_fn = switch_fn;
128 pb->current_child = -1;
129 pb->parent_id = parent_count++;
130 pb->mii_bus = parent_bus;
131
132 ret_val = -ENODEV;
133 for_each_available_child_of_node(mux_node, child_bus_node) {
134 int v;
135
136 r = of_property_read_u32(child_bus_node, "reg", &v);
137 if (r) {
138 dev_err(dev,
139 "Error: Failed to find reg for child %pOF\n",
140 child_bus_node);
141 continue;
142 }
143
144 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
145 if (!cb) {
146 ret_val = -ENOMEM;
147 continue;
148 }
149 cb->bus_number = v;
150 cb->parent = pb;
151
152 cb->mii_bus = mdiobus_alloc();
153 if (!cb->mii_bus) {
154 ret_val = -ENOMEM;
155 devm_kfree(dev, cb);
156 continue;
157 }
158 cb->mii_bus->priv = cb;
159
160 cb->mii_bus->name = "mdio_mux";
161 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
162 pb->parent_id, v);
163 cb->mii_bus->parent = dev;
164 cb->mii_bus->read = mdio_mux_read;
165 cb->mii_bus->write = mdio_mux_write;
166 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
167 if (r) {
168 dev_err(dev,
169 "Error: Failed to register MDIO bus for child %pOF\n",
170 child_bus_node);
171 mdiobus_free(cb->mii_bus);
172 devm_kfree(dev, cb);
173 } else {
174 cb->next = pb->children;
175 pb->children = cb;
176 }
177 }
178 if (pb->children) {
179 *mux_handle = pb;
180 return 0;
181 }
182
183 dev_err(dev, "Error: No acceptable child buses found\n");
184 devm_kfree(dev, pb);
185 err_pb_kz:
186 put_device(&parent_bus->dev);
187 err_parent_bus:
188 of_node_put(parent_bus_node);
189 return ret_val;
190 }
191 EXPORT_SYMBOL_GPL(mdio_mux_init);
192
mdio_mux_uninit(void * mux_handle)193 void mdio_mux_uninit(void *mux_handle)
194 {
195 struct mdio_mux_parent_bus *pb = mux_handle;
196 struct mdio_mux_child_bus *cb = pb->children;
197
198 while (cb) {
199 mdiobus_unregister(cb->mii_bus);
200 mdiobus_free(cb->mii_bus);
201 cb = cb->next;
202 }
203
204 put_device(&pb->mii_bus->dev);
205 }
206 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
207
208 MODULE_DESCRIPTION(DRV_DESCRIPTION);
209 MODULE_AUTHOR("David Daney");
210 MODULE_LICENSE("GPL v2");
211