/*
* Simple memory-mapped device MDIO MUX driver
*
* Author: Timur Tabi <timur@freescale.com>
*
* Copyright 2012 Freescale Semiconductor, Inc.
*
* This file is licensed under the terms of the GNU General Public License
* version 2. This program is licensed "as is" without any warranty of any
* kind, whether express or implied.
*/
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/of_address.h>
#include <linux/of_mdio.h>
#include <linux/module.h>
#include <linux/phy.h>
#include <linux/mdio-mux.h>
struct mdio_mux_mmioreg_state {
void *mux_handle;
phys_addr_t phys;
uint8_t mask;
};
/*
* MDIO multiplexing switch function
*
* This function is called by the mdio-mux layer when it thinks the mdio bus
* multiplexer needs to switch.
*
* 'current_child' is the current value of the mux register (masked via
* s->mask).
*
* 'desired_child' is the value of the 'reg' property of the target child MDIO
* node.
*
* The first time this function is called, current_child == -1.
*
* If current_child == desired_child, then the mux is already set to the
* correct bus.
*/
static int mdio_mux_mmioreg_switch_fn(int current_child, int desired_child,
void *data)
{
struct mdio_mux_mmioreg_state *s = data;
if (current_child ^ desired_child) {
void __iomem *p = ioremap(s->phys, 1);
uint8_t x, y;
if (!p)
return -ENOMEM;
x = ioread8(p);
y = (x & ~s->mask) | desired_child;
if (x != y) {
iowrite8((x & ~s->mask) | desired_child, p);
pr_debug("%s: %02x -> %02x\n", __func__, x, y);
}
iounmap(p);
}
return 0;
}
static int mdio_mux_mmioreg_probe(struct platform_device *pdev)
{
struct device_node *np2, *np = pdev->dev.of_node;
struct mdio_mux_mmioreg_state *s;
struct resource res;
const __be32 *iprop;
int len, ret;
dev_dbg(&pdev->dev, "probing node %s\n", np->full_name);
s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
ret = of_address_to_resource(np, 0, &res);
if (ret) {
dev_err(&pdev->dev, "could not obtain memory map for node %s\n",
np->full_name);
return ret;
}
s->phys = res.start;
if (resource_size(&res) != sizeof(uint8_t)) {
dev_err(&pdev->dev, "only 8-bit registers are supported\n");
return -EINVAL;
}
iprop = of_get_property(np, "mux-mask", &len);
if (!iprop || len != sizeof(uint32_t)) {
dev_err(&pdev->dev, "missing or invalid mux-mask property\n");
return -ENODEV;
}
if (be32_to_cpup(iprop) > 255) {
dev_err(&pdev->dev, "only 8-bit registers are supported\n");
return -EINVAL;
}
s->mask = be32_to_cpup(iprop);
/*
* Verify that the 'reg' property of each child MDIO bus does not
* set any bits outside of the 'mask'.
*/
for_each_available_child_of_node(np, np2) {
iprop = of_get_property(np2, "reg", &len);
if (!iprop || len != sizeof(uint32_t)) {
dev_err(&pdev->dev, "mdio-mux child node %s is "
"missing a 'reg' property\n", np2->full_name);
return -ENODEV;
}
if (be32_to_cpup(iprop) & ~s->mask) {
dev_err(&pdev->dev, "mdio-mux child node %s has "
"a 'reg' value with unmasked bits\n",
np2->full_name);
return -ENODEV;
}
}
ret = mdio_mux_init(&pdev->dev, mdio_mux_mmioreg_switch_fn,
&s->mux_handle, s);
if (ret) {
dev_err(&pdev->dev, "failed to register mdio-mux bus %s\n",
np->full_name);
return ret;
}
pdev->dev.platform_data = s;
return 0;
}
static int mdio_mux_mmioreg_remove(struct platform_device *pdev)
{
struct mdio_mux_mmioreg_state *s = dev_get_platdata(&pdev->dev);
mdio_mux_uninit(s->mux_handle);
return 0;
}
static struct of_device_id mdio_mux_mmioreg_match[] = {
{
.compatible = "mdio-mux-mmioreg",
},
{},
};
MODULE_DEVICE_TABLE(of, mdio_mux_mmioreg_match);
static struct platform_driver mdio_mux_mmioreg_driver = {
.driver = {
.name = "mdio-mux-mmioreg",
.of_match_table = mdio_mux_mmioreg_match,
},
.probe = mdio_mux_mmioreg_probe,
.remove = mdio_mux_mmioreg_remove,
};
module_platform_driver(mdio_mux_mmioreg_driver);
MODULE_AUTHOR("Timur Tabi <timur@freescale.com>");
MODULE_DESCRIPTION("Memory-mapped device MDIO MUX driver");
MODULE_LICENSE("GPL v2");
