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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2011, 2012 Cavium, Inc.
*/
#include <linux/platform_device.h>
#include <linux/mdio-mux.h>
#include <linux/of_mdio.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/phy.h>
#define DRV_VERSION "1.0"
#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;
int phy_irq[PHY_MAX_ADDR];
};
/*
* 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;
/* In theory multiple mdio_mux could be stacked, thus creating
* more than a single level of nesting. But in practice,
* SINGLE_DEPTH_NESTING will cover the vast majority of use
* cases. We use it, instead of trying to handle the general
* case.
*/
mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
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, SINGLE_DEPTH_NESTING);
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;
int mdio_mux_init(struct device *dev,
int (*switch_fn)(int cur, int desired, void *data),
void **mux_handle,
void *data)
{
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 (!dev->of_node)
return -ENODEV;
parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
if (!parent_bus_node)
return -ENODEV;
pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
if (pb == NULL) {
ret_val = -ENOMEM;
goto err_parent_bus;
}
parent_bus = of_mdio_find_bus(parent_bus_node);
if (parent_bus == NULL) {
ret_val = -EPROBE_DEFER;
goto err_parent_bus;
}
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(dev->of_node, child_bus_node) {
u32 v;
r = of_property_read_u32(child_bus_node, "reg", &v);
if (r)
continue;
cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
if (cb == NULL) {
dev_err(dev,
"Error: Failed to allocate memory for child\n");
ret_val = -ENOMEM;
break;
}
cb->bus_number = v;
cb->parent = pb;
cb->mii_bus = mdiobus_alloc();
cb->mii_bus->priv = cb;
cb->mii_bus->irq = cb->phy_irq;
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);
devm_kfree(dev, cb);
} else {
of_node_get(child_bus_node);
cb->next = pb->children;
pb->children = cb;
}
}
if (pb->children) {
*mux_handle = pb;
dev_info(dev, "Version " DRV_VERSION "\n");
return 0;
}
/* balance the reference of_mdio_find_bus() took */
put_device(&pb->mii_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;
struct mdio_mux_child_bus *cb = pb->children;
while (cb) {
mdiobus_unregister(cb->mii_bus);
mdiobus_free(cb->mii_bus);
cb = cb->next;
}
/* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
put_device(&pb->mii_bus->dev);
}
EXPORT_SYMBOL_GPL(mdio_mux_uninit);
MODULE_DESCRIPTION(DRV_DESCRIPTION);
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("David Daney");
MODULE_LICENSE("GPL");
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