xref: /openbmc/linux/drivers/net/mdio/mdio-mux.c (revision 1f9f2143)
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 
mdio_mux_read_c45(struct mii_bus * bus,int phy_id,int dev_addr,int regnum)58 static int mdio_mux_read_c45(struct mii_bus *bus, int phy_id, int dev_addr,
59 			     int regnum)
60 {
61 	struct mdio_mux_child_bus *cb = bus->priv;
62 	struct mdio_mux_parent_bus *pb = cb->parent;
63 	int r;
64 
65 	mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
66 	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
67 	if (r)
68 		goto out;
69 
70 	pb->current_child = cb->bus_number;
71 
72 	r = pb->mii_bus->read_c45(pb->mii_bus, phy_id, dev_addr, regnum);
73 out:
74 	mutex_unlock(&pb->mii_bus->mdio_lock);
75 
76 	return r;
77 }
78 
79 /*
80  * The parent bus' lock is used to order access to the switch_fn.
81  */
mdio_mux_write(struct mii_bus * bus,int phy_id,int regnum,u16 val)82 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
83 			  int regnum, u16 val)
84 {
85 	struct mdio_mux_child_bus *cb = bus->priv;
86 	struct mdio_mux_parent_bus *pb = cb->parent;
87 
88 	int r;
89 
90 	mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
91 	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
92 	if (r)
93 		goto out;
94 
95 	pb->current_child = cb->bus_number;
96 
97 	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
98 out:
99 	mutex_unlock(&pb->mii_bus->mdio_lock);
100 
101 	return r;
102 }
103 
mdio_mux_write_c45(struct mii_bus * bus,int phy_id,int dev_addr,int regnum,u16 val)104 static int mdio_mux_write_c45(struct mii_bus *bus, int phy_id, int dev_addr,
105 			      int regnum, u16 val)
106 {
107 	struct mdio_mux_child_bus *cb = bus->priv;
108 	struct mdio_mux_parent_bus *pb = cb->parent;
109 
110 	int r;
111 
112 	mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
113 	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
114 	if (r)
115 		goto out;
116 
117 	pb->current_child = cb->bus_number;
118 
119 	r = pb->mii_bus->write_c45(pb->mii_bus, phy_id, dev_addr, regnum, val);
120 out:
121 	mutex_unlock(&pb->mii_bus->mdio_lock);
122 
123 	return r;
124 }
125 
126 static int parent_count;
127 
mdio_mux_uninit_children(struct mdio_mux_parent_bus * pb)128 static void mdio_mux_uninit_children(struct mdio_mux_parent_bus *pb)
129 {
130 	struct mdio_mux_child_bus *cb = pb->children;
131 
132 	while (cb) {
133 		mdiobus_unregister(cb->mii_bus);
134 		mdiobus_free(cb->mii_bus);
135 		cb = cb->next;
136 	}
137 }
138 
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)139 int mdio_mux_init(struct device *dev,
140 		  struct device_node *mux_node,
141 		  int (*switch_fn)(int cur, int desired, void *data),
142 		  void **mux_handle,
143 		  void *data,
144 		  struct mii_bus *mux_bus)
145 {
146 	struct device_node *parent_bus_node;
147 	struct device_node *child_bus_node;
148 	int r, ret_val;
149 	struct mii_bus *parent_bus;
150 	struct mdio_mux_parent_bus *pb;
151 	struct mdio_mux_child_bus *cb;
152 
153 	if (!mux_node)
154 		return -ENODEV;
155 
156 	if (!mux_bus) {
157 		parent_bus_node = of_parse_phandle(mux_node,
158 						   "mdio-parent-bus", 0);
159 
160 		if (!parent_bus_node)
161 			return -ENODEV;
162 
163 		parent_bus = of_mdio_find_bus(parent_bus_node);
164 		if (!parent_bus) {
165 			ret_val = -EPROBE_DEFER;
166 			goto err_parent_bus;
167 		}
168 	} else {
169 		parent_bus_node = NULL;
170 		parent_bus = mux_bus;
171 		get_device(&parent_bus->dev);
172 	}
173 
174 	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
175 	if (!pb) {
176 		ret_val = -ENOMEM;
177 		goto err_pb_kz;
178 	}
179 
180 	pb->switch_data = data;
181 	pb->switch_fn = switch_fn;
182 	pb->current_child = -1;
183 	pb->parent_id = parent_count++;
184 	pb->mii_bus = parent_bus;
185 
186 	ret_val = -ENODEV;
187 	for_each_available_child_of_node(mux_node, child_bus_node) {
188 		int v;
189 
190 		r = of_property_read_u32(child_bus_node, "reg", &v);
191 		if (r) {
192 			dev_err(dev,
193 				"Error: Failed to find reg for child %pOF\n",
194 				child_bus_node);
195 			continue;
196 		}
197 
198 		cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
199 		if (!cb) {
200 			ret_val = -ENOMEM;
201 			goto err_loop;
202 		}
203 		cb->bus_number = v;
204 		cb->parent = pb;
205 
206 		cb->mii_bus = mdiobus_alloc();
207 		if (!cb->mii_bus) {
208 			ret_val = -ENOMEM;
209 			goto err_loop;
210 		}
211 		cb->mii_bus->priv = cb;
212 
213 		cb->mii_bus->name = "mdio_mux";
214 		snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%s-%x.%x",
215 			 cb->mii_bus->name, pb->parent_id, v);
216 		cb->mii_bus->parent = dev;
217 		cb->mii_bus->read = mdio_mux_read;
218 		cb->mii_bus->write = mdio_mux_write;
219 		if (parent_bus->read_c45)
220 			cb->mii_bus->read_c45 = mdio_mux_read_c45;
221 		if (parent_bus->write_c45)
222 			cb->mii_bus->write_c45 = mdio_mux_write_c45;
223 		r = of_mdiobus_register(cb->mii_bus, child_bus_node);
224 		if (r) {
225 			mdiobus_free(cb->mii_bus);
226 			if (r == -EPROBE_DEFER) {
227 				ret_val = r;
228 				goto err_loop;
229 			}
230 			devm_kfree(dev, cb);
231 			dev_err(dev,
232 				"Error: Failed to register MDIO bus for child %pOF\n",
233 				child_bus_node);
234 		} else {
235 			cb->next = pb->children;
236 			pb->children = cb;
237 		}
238 	}
239 	if (pb->children) {
240 		*mux_handle = pb;
241 		return 0;
242 	}
243 
244 	dev_err(dev, "Error: No acceptable child buses found\n");
245 
246 err_loop:
247 	mdio_mux_uninit_children(pb);
248 	of_node_put(child_bus_node);
249 err_pb_kz:
250 	put_device(&parent_bus->dev);
251 err_parent_bus:
252 	of_node_put(parent_bus_node);
253 	return ret_val;
254 }
255 EXPORT_SYMBOL_GPL(mdio_mux_init);
256 
mdio_mux_uninit(void * mux_handle)257 void mdio_mux_uninit(void *mux_handle)
258 {
259 	struct mdio_mux_parent_bus *pb = mux_handle;
260 
261 	mdio_mux_uninit_children(pb);
262 	put_device(&pb->mii_bus->dev);
263 }
264 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
265 
266 MODULE_DESCRIPTION(DRV_DESCRIPTION);
267 MODULE_AUTHOR("David Daney");
268 MODULE_LICENSE("GPL v2");
269