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};
 38
 39/*
 40 * The parent bus' lock is used to order access to the switch_fn.
 41 */
 42static 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	/* In theory multiple mdio_mux could be stacked, thus creating
 49	 * more than a single level of nesting.  But in practice,
 50	 * SINGLE_DEPTH_NESTING will cover the vast majority of use
 51	 * cases.  We use it, instead of trying to handle the general
 52	 * case.
 53	 */
 54	mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
 55	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
 56	if (r)
 57		goto out;
 58
 59	pb->current_child = cb->bus_number;
 60
 61	r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
 62out:
 63	mutex_unlock(&pb->mii_bus->mdio_lock);
 64
 65	return r;
 66}
 67
 68/*
 69 * The parent bus' lock is used to order access to the switch_fn.
 70 */
 71static int mdio_mux_write(struct mii_bus *bus, int phy_id,
 72			  int regnum, u16 val)
 73{
 74	struct mdio_mux_child_bus *cb = bus->priv;
 75	struct mdio_mux_parent_bus *pb = cb->parent;
 76
 77	int r;
 78
 79	mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
 80	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
 81	if (r)
 82		goto out;
 83
 84	pb->current_child = cb->bus_number;
 85
 86	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
 87out:
 88	mutex_unlock(&pb->mii_bus->mdio_lock);
 89
 90	return r;
 91}
 92
 93static int parent_count;
 94
 95int mdio_mux_init(struct device *dev,
 96		  int (*switch_fn)(int cur, int desired, void *data),
 97		  void **mux_handle,
 98		  void *data)
 99{
100	struct device_node *parent_bus_node;
101	struct device_node *child_bus_node;
102	int r, ret_val;
103	struct mii_bus *parent_bus;
104	struct mdio_mux_parent_bus *pb;
105	struct mdio_mux_child_bus *cb;
106
107	if (!dev->of_node)
108		return -ENODEV;
109
110	parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
111
112	if (!parent_bus_node)
113		return -ENODEV;
114
115	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
116	if (pb == NULL) {
117		ret_val = -ENOMEM;
118		goto err_parent_bus;
119	}
120
121	parent_bus = of_mdio_find_bus(parent_bus_node);
122	if (parent_bus == NULL) {
123		ret_val = -EPROBE_DEFER;
124		goto err_parent_bus;
125	}
126
127	pb->switch_data = data;
128	pb->switch_fn = switch_fn;
129	pb->current_child = -1;
130	pb->parent_id = parent_count++;
131	pb->mii_bus = parent_bus;
132
133	ret_val = -ENODEV;
134	for_each_available_child_of_node(dev->of_node, child_bus_node) {
135		u32 v;
136
137		r = of_property_read_u32(child_bus_node, "reg", &v);
138		if (r)
139			continue;
140
141		cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
142		if (cb == NULL) {
143			dev_err(dev,
144				"Error: Failed to allocate memory for child\n");
145			ret_val = -ENOMEM;
146			of_node_put(child_bus_node);
147			break;
148		}
149		cb->bus_number = v;
150		cb->parent = pb;
151
152		cb->mii_bus = mdiobus_alloc();
153		if (!cb->mii_bus) {
154			ret_val = -ENOMEM;
155			of_node_put(child_bus_node);
156			break;
157		}
158		cb->mii_bus->priv = cb;
159
160		cb->mii_bus->name = "mdio_mux";
161		snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
162			 pb->parent_id, v);
163		cb->mii_bus->parent = dev;
164		cb->mii_bus->read = mdio_mux_read;
165		cb->mii_bus->write = mdio_mux_write;
166		r = of_mdiobus_register(cb->mii_bus, child_bus_node);
167		if (r) {
168			mdiobus_free(cb->mii_bus);
169			devm_kfree(dev, cb);
170		} else {
171			of_node_get(child_bus_node);
172			cb->next = pb->children;
173			pb->children = cb;
174		}
175	}
176	if (pb->children) {
177		*mux_handle = pb;
178		dev_info(dev, "Version " DRV_VERSION "\n");
179		return 0;
180	}
181
182	/* balance the reference of_mdio_find_bus() took */
183	put_device(&pb->mii_bus->dev);
184
185err_parent_bus:
186	of_node_put(parent_bus_node);
187	return ret_val;
188}
189EXPORT_SYMBOL_GPL(mdio_mux_init);
190
191void mdio_mux_uninit(void *mux_handle)
192{
193	struct mdio_mux_parent_bus *pb = mux_handle;
194	struct mdio_mux_child_bus *cb = pb->children;
195
196	while (cb) {
197		mdiobus_unregister(cb->mii_bus);
198		mdiobus_free(cb->mii_bus);
199		cb = cb->next;
200	}
201
202	/* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
203	put_device(&pb->mii_bus->dev);
204}
205EXPORT_SYMBOL_GPL(mdio_mux_uninit);
206
207MODULE_DESCRIPTION(DRV_DESCRIPTION);
208MODULE_VERSION(DRV_VERSION);
209MODULE_AUTHOR("David Daney");
210MODULE_LICENSE("GPL");