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");