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
19struct mdio_mux_child_bus;
20
21struct 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
32struct 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	int phy_irq[PHY_MAX_ADDR];
38};
39
40/*
41 * The parent bus' lock is used to order access to the switch_fn.
42 */
43static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
44{
45	struct mdio_mux_child_bus *cb = bus->priv;
46	struct mdio_mux_parent_bus *pb = cb->parent;
47	int r;
48
49	/* In theory multiple mdio_mux could be stacked, thus creating
50	 * more than a single level of nesting.  But in practice,
51	 * SINGLE_DEPTH_NESTING will cover the vast majority of use
52	 * cases.  We use it, instead of trying to handle the general
53	 * case.
54	 */
55	mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
56	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
57	if (r)
58		goto out;
59
60	pb->current_child = cb->bus_number;
61
62	r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
63out:
64	mutex_unlock(&pb->mii_bus->mdio_lock);
65
66	return r;
67}
68
69/*
70 * The parent bus' lock is used to order access to the switch_fn.
71 */
72static int mdio_mux_write(struct mii_bus *bus, int phy_id,
73			  int regnum, u16 val)
74{
75	struct mdio_mux_child_bus *cb = bus->priv;
76	struct mdio_mux_parent_bus *pb = cb->parent;
77
78	int r;
79
80	mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
81	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
82	if (r)
83		goto out;
84
85	pb->current_child = cb->bus_number;
86
87	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
88out:
89	mutex_unlock(&pb->mii_bus->mdio_lock);
90
91	return r;
92}
93
94static int parent_count;
95
96int mdio_mux_init(struct device *dev,
97		  int (*switch_fn)(int cur, int desired, void *data),
98		  void **mux_handle,
99		  void *data)
100{
101	struct device_node *parent_bus_node;
102	struct device_node *child_bus_node;
103	int r, ret_val;
104	struct mii_bus *parent_bus;
105	struct mdio_mux_parent_bus *pb;
106	struct mdio_mux_child_bus *cb;
107
108	if (!dev->of_node)
109		return -ENODEV;
110
111	parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
112
113	if (!parent_bus_node)
114		return -ENODEV;
115
116	parent_bus = of_mdio_find_bus(parent_bus_node);
117	if (parent_bus == NULL) {
118		ret_val = -EPROBE_DEFER;
119		goto err_parent_bus;
120	}
121
122	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
123	if (pb == NULL) {
124		ret_val = -ENOMEM;
125		goto err_parent_bus;
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			break;
148		}
149		cb->bus_number = v;
150		cb->parent = pb;
151		cb->mii_bus = mdiobus_alloc();
152		cb->mii_bus->priv = cb;
153
154		cb->mii_bus->irq = cb->phy_irq;
155		cb->mii_bus->name = "mdio_mux";
156		snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
157			 pb->parent_id, v);
158		cb->mii_bus->parent = dev;
159		cb->mii_bus->read = mdio_mux_read;
160		cb->mii_bus->write = mdio_mux_write;
161		r = of_mdiobus_register(cb->mii_bus, child_bus_node);
162		if (r) {
163			mdiobus_free(cb->mii_bus);
164			devm_kfree(dev, cb);
165		} else {
166			of_node_get(child_bus_node);
167			cb->next = pb->children;
168			pb->children = cb;
169		}
170	}
171	if (pb->children) {
172		*mux_handle = pb;
173		dev_info(dev, "Version " DRV_VERSION "\n");
174		return 0;
175	}
176err_parent_bus:
177	of_node_put(parent_bus_node);
178	return ret_val;
179}
180EXPORT_SYMBOL_GPL(mdio_mux_init);
181
182void mdio_mux_uninit(void *mux_handle)
183{
184	struct mdio_mux_parent_bus *pb = mux_handle;
185	struct mdio_mux_child_bus *cb = pb->children;
186
187	while (cb) {
188		mdiobus_unregister(cb->mii_bus);
189		mdiobus_free(cb->mii_bus);
190		cb = cb->next;
191	}
192}
193EXPORT_SYMBOL_GPL(mdio_mux_uninit);
194
195MODULE_DESCRIPTION(DRV_DESCRIPTION);
196MODULE_VERSION(DRV_VERSION);
197MODULE_AUTHOR("David Daney");
198MODULE_LICENSE("GPL");
199