1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2011, 2012 Cavium, Inc.
  4 */
  5
  6#include <linux/device.h>
  7#include <linux/mdio-mux.h>
  8#include <linux/module.h>
  9#include <linux/of_mdio.h>
 10#include <linux/phy.h>
 11#include <linux/platform_device.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
 85static void mdio_mux_uninit_children(struct mdio_mux_parent_bus *pb)
 86{
 87	struct mdio_mux_child_bus *cb = pb->children;
 88
 89	while (cb) {
 90		mdiobus_unregister(cb->mii_bus);
 91		mdiobus_free(cb->mii_bus);
 92		cb = cb->next;
 93	}
 94}
 95
 96int mdio_mux_init(struct device *dev,
 97		  struct device_node *mux_node,
 98		  int (*switch_fn)(int cur, int desired, void *data),
 99		  void **mux_handle,
100		  void *data,
101		  struct mii_bus *mux_bus)
102{
103	struct device_node *parent_bus_node;
104	struct device_node *child_bus_node;
105	int r, ret_val;
106	struct mii_bus *parent_bus;
107	struct mdio_mux_parent_bus *pb;
108	struct mdio_mux_child_bus *cb;
109
110	if (!mux_node)
111		return -ENODEV;
112
113	if (!mux_bus) {
114		parent_bus_node = of_parse_phandle(mux_node,
115						   "mdio-parent-bus", 0);
116
117		if (!parent_bus_node)
118			return -ENODEV;
119
120		parent_bus = of_mdio_find_bus(parent_bus_node);
121		if (!parent_bus) {
122			ret_val = -EPROBE_DEFER;
123			goto err_parent_bus;
124		}
125	} else {
126		parent_bus_node = NULL;
127		parent_bus = mux_bus;
128		get_device(&parent_bus->dev);
129	}
130
131	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
132	if (!pb) {
133		ret_val = -ENOMEM;
134		goto err_pb_kz;
135	}
136
137	pb->switch_data = data;
138	pb->switch_fn = switch_fn;
139	pb->current_child = -1;
140	pb->parent_id = parent_count++;
141	pb->mii_bus = parent_bus;
142
143	ret_val = -ENODEV;
144	for_each_available_child_of_node(mux_node, child_bus_node) {
145		int v;
146
147		r = of_property_read_u32(child_bus_node, "reg", &v);
148		if (r) {
149			dev_err(dev,
150				"Error: Failed to find reg for child %pOF\n",
151				child_bus_node);
152			continue;
153		}
154
155		cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
156		if (!cb) {
157			ret_val = -ENOMEM;
158			goto err_loop;
159		}
160		cb->bus_number = v;
161		cb->parent = pb;
162
163		cb->mii_bus = mdiobus_alloc();
164		if (!cb->mii_bus) {
165			ret_val = -ENOMEM;
166			goto err_loop;
167		}
168		cb->mii_bus->priv = cb;
169
170		cb->mii_bus->name = "mdio_mux";
171		snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
172			 pb->parent_id, v);
173		cb->mii_bus->parent = dev;
174		cb->mii_bus->read = mdio_mux_read;
175		cb->mii_bus->write = mdio_mux_write;
176		r = of_mdiobus_register(cb->mii_bus, child_bus_node);
177		if (r) {
178			mdiobus_free(cb->mii_bus);
179			if (r == -EPROBE_DEFER) {
180				ret_val = r;
181				goto err_loop;
182			}
183			devm_kfree(dev, cb);
184			dev_err(dev,
185				"Error: Failed to register MDIO bus for child %pOF\n",
186				child_bus_node);
187		} else {
188			cb->next = pb->children;
189			pb->children = cb;
190		}
191	}
192	if (pb->children) {
193		*mux_handle = pb;
194		return 0;
195	}
196
197	dev_err(dev, "Error: No acceptable child buses found\n");
198
199err_loop:
200	mdio_mux_uninit_children(pb);
201	of_node_put(child_bus_node);
202err_pb_kz:
203	put_device(&parent_bus->dev);
204err_parent_bus:
205	of_node_put(parent_bus_node);
206	return ret_val;
207}
208EXPORT_SYMBOL_GPL(mdio_mux_init);
209
210void mdio_mux_uninit(void *mux_handle)
211{
212	struct mdio_mux_parent_bus *pb = mux_handle;
213
214	mdio_mux_uninit_children(pb);
215	put_device(&pb->mii_bus->dev);
216}
217EXPORT_SYMBOL_GPL(mdio_mux_uninit);
218
219MODULE_DESCRIPTION(DRV_DESCRIPTION);
220MODULE_AUTHOR("David Daney");
221MODULE_LICENSE("GPL v2");