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_VERSION "1.0"
17 #define DRV_DESCRIPTION "MDIO bus multiplexer driver"
18
19 struct mdio_mux_child_bus;
20
21 struct mdio_mux_parent_bus {
22 struct mii_bus *mii_bus;
23 int current_child;
24 int parent_id;
25 void *switch_data;
26 int (*switch_fn)(int current_child, int desired_child, void *data);
27
28 /* List of our children linked through their next fields. */
29 struct mdio_mux_child_bus *children;
30 };
31
32 struct mdio_mux_child_bus {
33 struct mii_bus *mii_bus;
34 struct mdio_mux_parent_bus *parent;
35 struct mdio_mux_child_bus *next;
36 int bus_number;
37 };
38
39 /*
40 * The parent bus' lock is used to order access to the switch_fn.
41 */
mdio_mux_read(struct mii_bus * bus,int phy_id,int regnum)42 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
43 {
44 struct mdio_mux_child_bus *cb = bus->priv;
45 struct mdio_mux_parent_bus *pb = cb->parent;
46 int r;
47
48 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
49 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
50 if (r)
51 goto out;
52
53 pb->current_child = cb->bus_number;
54
55 r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
56 out:
57 mutex_unlock(&pb->mii_bus->mdio_lock);
58
59 return r;
60 }
61
62 /*
63 * The parent bus' lock is used to order access to the switch_fn.
64 */
mdio_mux_write(struct mii_bus * bus,int phy_id,int regnum,u16 val)65 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
66 int regnum, u16 val)
67 {
68 struct mdio_mux_child_bus *cb = bus->priv;
69 struct mdio_mux_parent_bus *pb = cb->parent;
70
71 int r;
72
73 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
74 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
75 if (r)
76 goto out;
77
78 pb->current_child = cb->bus_number;
79
80 r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
81 out:
82 mutex_unlock(&pb->mii_bus->mdio_lock);
83
84 return r;
85 }
86
87 static int parent_count;
88
mdio_mux_init(struct device * dev,int (* switch_fn)(int cur,int desired,void * data),void ** mux_handle,void * data,struct mii_bus * mux_bus)89 int mdio_mux_init(struct device *dev,
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 (!dev->of_node)
103 return -ENODEV;
104
105 if (!mux_bus) {
106 parent_bus_node = of_parse_phandle(dev->of_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 }
121
122 pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
123 if (pb == NULL) {
124 ret_val = -ENOMEM;
125 goto err_pb_kz;
126 }
127
128 pb->switch_data = data;
129 pb->switch_fn = switch_fn;
130 pb->current_child = -1;
131 pb->parent_id = parent_count++;
132 pb->mii_bus = parent_bus;
133
134 ret_val = -ENODEV;
135 for_each_available_child_of_node(dev->of_node, child_bus_node) {
136 u32 v;
137
138 r = of_property_read_u32(child_bus_node, "reg", &v);
139 if (r)
140 continue;
141
142 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
143 if (cb == NULL) {
144 dev_err(dev,
145 "Error: Failed to allocate memory for child\n");
146 ret_val = -ENOMEM;
147 of_node_put(child_bus_node);
148 break;
149 }
150 cb->bus_number = v;
151 cb->parent = pb;
152
153 cb->mii_bus = mdiobus_alloc();
154 if (!cb->mii_bus) {
155 ret_val = -ENOMEM;
156 devm_kfree(dev, cb);
157 of_node_put(child_bus_node);
158 break;
159 }
160 cb->mii_bus->priv = cb;
161
162 cb->mii_bus->name = "mdio_mux";
163 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
164 pb->parent_id, v);
165 cb->mii_bus->parent = dev;
166 cb->mii_bus->read = mdio_mux_read;
167 cb->mii_bus->write = mdio_mux_write;
168 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
169 if (r) {
170 mdiobus_free(cb->mii_bus);
171 devm_kfree(dev, cb);
172 } else {
173 cb->next = pb->children;
174 pb->children = cb;
175 }
176 }
177 if (pb->children) {
178 *mux_handle = pb;
179 dev_info(dev, "Version " DRV_VERSION "\n");
180 return 0;
181 }
182
183 devm_kfree(dev, pb);
184 err_pb_kz:
185 /* balance the reference of_mdio_find_bus() took */
186 if (!mux_bus)
187 put_device(&parent_bus->dev);
188 err_parent_bus:
189 of_node_put(parent_bus_node);
190 return ret_val;
191 }
192 EXPORT_SYMBOL_GPL(mdio_mux_init);
193
mdio_mux_uninit(void * mux_handle)194 void mdio_mux_uninit(void *mux_handle)
195 {
196 struct mdio_mux_parent_bus *pb = mux_handle;
197 struct mdio_mux_child_bus *cb = pb->children;
198
199 while (cb) {
200 mdiobus_unregister(cb->mii_bus);
201 mdiobus_free(cb->mii_bus);
202 cb = cb->next;
203 }
204
205 /* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
206 put_device(&pb->mii_bus->dev);
207 }
208 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
209
210 MODULE_DESCRIPTION(DRV_DESCRIPTION);
211 MODULE_VERSION(DRV_VERSION);
212 MODULE_AUTHOR("David Daney");
213 MODULE_LICENSE("GPL");
214