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_uninit_children(struct mdio_mux_parent_bus * pb)85 static 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 
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)96 int 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, "%s-%x.%x",
172 			 cb->mii_bus->name, 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 
199 err_loop:
200 	mdio_mux_uninit_children(pb);
201 	of_node_put(child_bus_node);
202 err_pb_kz:
203 	put_device(&parent_bus->dev);
204 err_parent_bus:
205 	of_node_put(parent_bus_node);
206 	return ret_val;
207 }
208 EXPORT_SYMBOL_GPL(mdio_mux_init);
209 
mdio_mux_uninit(void * mux_handle)210 void mdio_mux_uninit(void *mux_handle)
211 {
212 	struct mdio_mux_parent_bus *pb = mux_handle;
213 
214 	mdio_mux_uninit_children(pb);
215 	put_device(&pb->mii_bus->dev);
216 }
217 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
218 
219 MODULE_DESCRIPTION(DRV_DESCRIPTION);
220 MODULE_AUTHOR("David Daney");
221 MODULE_LICENSE("GPL v2");
222