1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2011, 2012 Cavium, Inc.
  4 */
  5
  6#include <linux/platform_device.h>
  7#include <linux/mdio-mux.h>
  8#include <linux/of_mdio.h>
  9#include <linux/device.h>
 10#include <linux/module.h>
 11#include <linux/phy.h>
 12
 13#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
 14
 15struct mdio_mux_child_bus;
 16
 17struct 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
 28struct 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 */
 38static 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);
 52out:
 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 */
 61static 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);
 77out:
 78	mutex_unlock(&pb->mii_bus->mdio_lock);
 79
 80	return r;
 81}
 82
 83static int parent_count;
 84
 85int mdio_mux_init(struct device *dev,
 86		  struct device_node *mux_node,
 87		  int (*switch_fn)(int cur, int desired, void *data),
 88		  void **mux_handle,
 89		  void *data,
 90		  struct mii_bus *mux_bus)
 91{
 92	struct device_node *parent_bus_node;
 93	struct device_node *child_bus_node;
 94	int r, ret_val;
 95	struct mii_bus *parent_bus;
 96	struct mdio_mux_parent_bus *pb;
 97	struct mdio_mux_child_bus *cb;
 98
 99	if (!mux_node)
100		return -ENODEV;
101
102	if (!mux_bus) {
103		parent_bus_node = of_parse_phandle(mux_node,
104						   "mdio-parent-bus", 0);
105
106		if (!parent_bus_node)
107			return -ENODEV;
108
109		parent_bus = of_mdio_find_bus(parent_bus_node);
110		if (!parent_bus) {
111			ret_val = -EPROBE_DEFER;
112			goto err_parent_bus;
113		}
114	} else {
115		parent_bus_node = NULL;
116		parent_bus = mux_bus;
117		get_device(&parent_bus->dev);
118	}
119
120	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
121	if (!pb) {
122		ret_val = -ENOMEM;
123		goto err_pb_kz;
124	}
125
126	pb->switch_data = data;
127	pb->switch_fn = switch_fn;
128	pb->current_child = -1;
129	pb->parent_id = parent_count++;
130	pb->mii_bus = parent_bus;
131
132	ret_val = -ENODEV;
133	for_each_available_child_of_node(mux_node, child_bus_node) {
134		int v;
135
136		r = of_property_read_u32(child_bus_node, "reg", &v);
137		if (r) {
138			dev_err(dev,
139				"Error: Failed to find reg for child %pOF\n",
140				child_bus_node);
141			continue;
142		}
143
144		cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
145		if (!cb) {
146			ret_val = -ENOMEM;
147			continue;
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			devm_kfree(dev, cb);
156			continue;
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			dev_err(dev,
169				"Error: Failed to register MDIO bus for child %pOF\n",
170				child_bus_node);
171			mdiobus_free(cb->mii_bus);
172			devm_kfree(dev, cb);
173		} else {
174			cb->next = pb->children;
175			pb->children = cb;
176		}
177	}
178	if (pb->children) {
179		*mux_handle = pb;
180		return 0;
181	}
182
183	dev_err(dev, "Error: No acceptable child buses found\n");
184	devm_kfree(dev, pb);
185err_pb_kz:
186	put_device(&parent_bus->dev);
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	put_device(&pb->mii_bus->dev);
205}
206EXPORT_SYMBOL_GPL(mdio_mux_uninit);
207
208MODULE_DESCRIPTION(DRV_DESCRIPTION);
209MODULE_AUTHOR("David Daney");
210MODULE_LICENSE("GPL v2");