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	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);
 56out:
 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 */
 65static 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);
 81out:
 82	mutex_unlock(&pb->mii_bus->mdio_lock);
 83
 84	return r;
 85}
 86
 87static int parent_count;
 88
 89int 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_parent_bus;
126	}
127
128
129	pb->switch_data = data;
130	pb->switch_fn = switch_fn;
131	pb->current_child = -1;
132	pb->parent_id = parent_count++;
133	pb->mii_bus = parent_bus;
134
135	ret_val = -ENODEV;
136	for_each_available_child_of_node(dev->of_node, child_bus_node) {
137		u32 v;
138
139		r = of_property_read_u32(child_bus_node, "reg", &v);
140		if (r)
141			continue;
142
143		cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
144		if (cb == NULL) {
145			dev_err(dev,
146				"Error: Failed to allocate memory for child\n");
147			ret_val = -ENOMEM;
148			of_node_put(child_bus_node);
149			break;
150		}
151		cb->bus_number = v;
152		cb->parent = pb;
153
154		cb->mii_bus = mdiobus_alloc();
155		if (!cb->mii_bus) {
156			ret_val = -ENOMEM;
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			of_node_get(child_bus_node);
174			cb->next = pb->children;
175			pb->children = cb;
176		}
177	}
178	if (pb->children) {
179		*mux_handle = pb;
180		dev_info(dev, "Version " DRV_VERSION "\n");
181		return 0;
182	}
183
184	/* balance the reference of_mdio_find_bus() took */
185	put_device(&pb->mii_bus->dev);
186
187err_parent_bus:
188	of_node_put(parent_bus_node);
189	return ret_val;
190}
191EXPORT_SYMBOL_GPL(mdio_mux_init);
192
193void mdio_mux_uninit(void *mux_handle)
194{
195	struct mdio_mux_parent_bus *pb = mux_handle;
196	struct mdio_mux_child_bus *cb = pb->children;
197
198	while (cb) {
199		mdiobus_unregister(cb->mii_bus);
200		mdiobus_free(cb->mii_bus);
201		cb = cb->next;
202	}
203
204	/* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
205	put_device(&pb->mii_bus->dev);
206}
207EXPORT_SYMBOL_GPL(mdio_mux_uninit);
208
209MODULE_DESCRIPTION(DRV_DESCRIPTION);
210MODULE_VERSION(DRV_VERSION);
211MODULE_AUTHOR("David Daney");
212MODULE_LICENSE("GPL");