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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2011, 2012 Cavium, Inc.
*/
#include <linux/device.h>
#include <linux/mdio-mux.h>
#include <linux/module.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
struct mdio_mux_child_bus;
struct mdio_mux_parent_bus {
struct mii_bus *mii_bus;
int current_child;
int parent_id;
void *switch_data;
int (*switch_fn)(int current_child, int desired_child, void *data);
/* List of our children linked through their next fields. */
struct mdio_mux_child_bus *children;
};
struct mdio_mux_child_bus {
struct mii_bus *mii_bus;
struct mdio_mux_parent_bus *parent;
struct mdio_mux_child_bus *next;
int bus_number;
};
/*
* The parent bus' lock is used to order access to the switch_fn.
*/
static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
{
struct mdio_mux_child_bus *cb = bus->priv;
struct mdio_mux_parent_bus *pb = cb->parent;
int r;
mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
if (r)
goto out;
pb->current_child = cb->bus_number;
r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
out:
mutex_unlock(&pb->mii_bus->mdio_lock);
return r;
}
/*
* The parent bus' lock is used to order access to the switch_fn.
*/
static int mdio_mux_write(struct mii_bus *bus, int phy_id,
int regnum, u16 val)
{
struct mdio_mux_child_bus *cb = bus->priv;
struct mdio_mux_parent_bus *pb = cb->parent;
int r;
mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
if (r)
goto out;
pb->current_child = cb->bus_number;
r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
out:
mutex_unlock(&pb->mii_bus->mdio_lock);
return r;
}
static int parent_count;
static void mdio_mux_uninit_children(struct mdio_mux_parent_bus *pb)
{
struct mdio_mux_child_bus *cb = pb->children;
while (cb) {
mdiobus_unregister(cb->mii_bus);
mdiobus_free(cb->mii_bus);
cb = cb->next;
}
}
int mdio_mux_init(struct device *dev,
struct device_node *mux_node,
int (*switch_fn)(int cur, int desired, void *data),
void **mux_handle,
void *data,
struct mii_bus *mux_bus)
{
struct device_node *parent_bus_node;
struct device_node *child_bus_node;
int r, ret_val;
struct mii_bus *parent_bus;
struct mdio_mux_parent_bus *pb;
struct mdio_mux_child_bus *cb;
if (!mux_node)
return -ENODEV;
if (!mux_bus) {
parent_bus_node = of_parse_phandle(mux_node,
"mdio-parent-bus", 0);
if (!parent_bus_node)
return -ENODEV;
parent_bus = of_mdio_find_bus(parent_bus_node);
if (!parent_bus) {
ret_val = -EPROBE_DEFER;
goto err_parent_bus;
}
} else {
parent_bus_node = NULL;
parent_bus = mux_bus;
get_device(&parent_bus->dev);
}
pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
if (!pb) {
ret_val = -ENOMEM;
goto err_pb_kz;
}
pb->switch_data = data;
pb->switch_fn = switch_fn;
pb->current_child = -1;
pb->parent_id = parent_count++;
pb->mii_bus = parent_bus;
ret_val = -ENODEV;
for_each_available_child_of_node(mux_node, child_bus_node) {
int v;
r = of_property_read_u32(child_bus_node, "reg", &v);
if (r) {
dev_err(dev,
"Error: Failed to find reg for child %pOF\n",
child_bus_node);
continue;
}
cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
if (!cb) {
ret_val = -ENOMEM;
goto err_loop;
}
cb->bus_number = v;
cb->parent = pb;
cb->mii_bus = mdiobus_alloc();
if (!cb->mii_bus) {
ret_val = -ENOMEM;
goto err_loop;
}
cb->mii_bus->priv = cb;
cb->mii_bus->name = "mdio_mux";
snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
pb->parent_id, v);
cb->mii_bus->parent = dev;
cb->mii_bus->read = mdio_mux_read;
cb->mii_bus->write = mdio_mux_write;
r = of_mdiobus_register(cb->mii_bus, child_bus_node);
if (r) {
mdiobus_free(cb->mii_bus);
if (r == -EPROBE_DEFER) {
ret_val = r;
goto err_loop;
}
devm_kfree(dev, cb);
dev_err(dev,
"Error: Failed to register MDIO bus for child %pOF\n",
child_bus_node);
} else {
cb->next = pb->children;
pb->children = cb;
}
}
if (pb->children) {
*mux_handle = pb;
return 0;
}
dev_err(dev, "Error: No acceptable child buses found\n");
devm_kfree(dev, pb);
err_loop:
mdio_mux_uninit_children(pb);
of_node_put(child_bus_node);
err_pb_kz:
put_device(&parent_bus->dev);
err_parent_bus:
of_node_put(parent_bus_node);
return ret_val;
}
EXPORT_SYMBOL_GPL(mdio_mux_init);
void mdio_mux_uninit(void *mux_handle)
{
struct mdio_mux_parent_bus *pb = mux_handle;
mdio_mux_uninit_children(pb);
put_device(&pb->mii_bus->dev);
}
EXPORT_SYMBOL_GPL(mdio_mux_uninit);
MODULE_DESCRIPTION(DRV_DESCRIPTION);
MODULE_AUTHOR("David Daney");
MODULE_LICENSE("GPL v2");
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