1 /*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2011, 2012 Cavium, Inc.
7 */
8
9 #include <linux/platform_device.h>
10 #include <linux/mdio-mux.h>
11 #include <linux/of_mdio.h>
12 #include <linux/device.h>
13 #include <linux/module.h>
14 #include <linux/phy.h>
15
16 #define DRV_DESCRIPTION "MDIO bus multiplexer driver"
17
18 struct mdio_mux_child_bus;
19
20 struct mdio_mux_parent_bus {
21 struct mii_bus *mii_bus;
22 int current_child;
23 int parent_id;
24 void *switch_data;
25 int (*switch_fn)(int current_child, int desired_child, void *data);
26
27 /* List of our children linked through their next fields. */
28 struct mdio_mux_child_bus *children;
29 };
30
31 struct mdio_mux_child_bus {
32 struct mii_bus *mii_bus;
33 struct mdio_mux_parent_bus *parent;
34 struct mdio_mux_child_bus *next;
35 int bus_number;
36 };
37
38 /*
39 * The parent bus' lock is used to order access to the switch_fn.
40 */
mdio_mux_read(struct mii_bus * bus,int phy_id,int regnum)41 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
42 {
43 struct mdio_mux_child_bus *cb = bus->priv;
44 struct mdio_mux_parent_bus *pb = cb->parent;
45 int r;
46
47 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
48 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
49 if (r)
50 goto out;
51
52 pb->current_child = cb->bus_number;
53
54 r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
55 out:
56 mutex_unlock(&pb->mii_bus->mdio_lock);
57
58 return r;
59 }
60
61 /*
62 * The parent bus' lock is used to order access to the switch_fn.
63 */
mdio_mux_write(struct mii_bus * bus,int phy_id,int regnum,u16 val)64 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
65 int regnum, u16 val)
66 {
67 struct mdio_mux_child_bus *cb = bus->priv;
68 struct mdio_mux_parent_bus *pb = cb->parent;
69
70 int r;
71
72 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
73 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
74 if (r)
75 goto out;
76
77 pb->current_child = cb->bus_number;
78
79 r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
80 out:
81 mutex_unlock(&pb->mii_bus->mdio_lock);
82
83 return r;
84 }
85
86 static int parent_count;
87
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)88 int mdio_mux_init(struct device *dev,
89 struct device_node *mux_node,
90 int (*switch_fn)(int cur, int desired, void *data),
91 void **mux_handle,
92 void *data,
93 struct mii_bus *mux_bus)
94 {
95 struct device_node *parent_bus_node;
96 struct device_node *child_bus_node;
97 int r, ret_val;
98 struct mii_bus *parent_bus;
99 struct mdio_mux_parent_bus *pb;
100 struct mdio_mux_child_bus *cb;
101
102 if (!mux_node)
103 return -ENODEV;
104
105 if (!mux_bus) {
106 parent_bus_node = of_parse_phandle(mux_node,
107 "mdio-parent-bus", 0);
108
109 if (!parent_bus_node)
110 return -ENODEV;
111
112 parent_bus = of_mdio_find_bus(parent_bus_node);
113 if (!parent_bus) {
114 ret_val = -EPROBE_DEFER;
115 goto err_parent_bus;
116 }
117 } else {
118 parent_bus_node = NULL;
119 parent_bus = mux_bus;
120 get_device(&parent_bus->dev);
121 }
122
123 pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
124 if (!pb) {
125 ret_val = -ENOMEM;
126 goto err_pb_kz;
127 }
128
129 pb->switch_data = data;
130 pb->switch_fn = switch_fn;
131 pb->current_child = -1;
132 pb->parent_id = parent_count++;
133 pb->mii_bus = parent_bus;
134
135 ret_val = -ENODEV;
136 for_each_available_child_of_node(mux_node, child_bus_node) {
137 int v;
138
139 r = of_property_read_u32(child_bus_node, "reg", &v);
140 if (r) {
141 dev_err(dev,
142 "Error: Failed to find reg for child %pOF\n",
143 child_bus_node);
144 continue;
145 }
146
147 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
148 if (!cb) {
149 ret_val = -ENOMEM;
150 continue;
151 }
152 cb->bus_number = v;
153 cb->parent = pb;
154
155 cb->mii_bus = mdiobus_alloc();
156 if (!cb->mii_bus) {
157 ret_val = -ENOMEM;
158 devm_kfree(dev, cb);
159 continue;
160 }
161 cb->mii_bus->priv = cb;
162
163 cb->mii_bus->name = "mdio_mux";
164 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
165 pb->parent_id, v);
166 cb->mii_bus->parent = dev;
167 cb->mii_bus->read = mdio_mux_read;
168 cb->mii_bus->write = mdio_mux_write;
169 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
170 if (r) {
171 dev_err(dev,
172 "Error: Failed to register MDIO bus for child %pOF\n",
173 child_bus_node);
174 mdiobus_free(cb->mii_bus);
175 devm_kfree(dev, cb);
176 } else {
177 cb->next = pb->children;
178 pb->children = cb;
179 }
180 }
181 if (pb->children) {
182 *mux_handle = pb;
183 return 0;
184 }
185
186 dev_err(dev, "Error: No acceptable child buses found\n");
187 devm_kfree(dev, pb);
188 err_pb_kz:
189 put_device(&parent_bus->dev);
190 err_parent_bus:
191 of_node_put(parent_bus_node);
192 return ret_val;
193 }
194 EXPORT_SYMBOL_GPL(mdio_mux_init);
195
mdio_mux_uninit(void * mux_handle)196 void mdio_mux_uninit(void *mux_handle)
197 {
198 struct mdio_mux_parent_bus *pb = mux_handle;
199 struct mdio_mux_child_bus *cb = pb->children;
200
201 while (cb) {
202 mdiobus_unregister(cb->mii_bus);
203 mdiobus_free(cb->mii_bus);
204 cb = cb->next;
205 }
206
207 put_device(&pb->mii_bus->dev);
208 }
209 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
210
211 MODULE_DESCRIPTION(DRV_DESCRIPTION);
212 MODULE_AUTHOR("David Daney");
213 MODULE_LICENSE("GPL");
214