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// SPDX-License-Identifier: GPL-2.0+
/* MDIO bus multiplexer using kernel multiplexer subsystem
*
* Copyright 2019 NXP
*/
#include <linux/platform_device.h>
#include <linux/mdio-mux.h>
#include <linux/module.h>
#include <linux/mux/consumer.h>
struct mdio_mux_multiplexer_state {
struct mux_control *muxc;
bool do_deselect;
void *mux_handle;
};
/**
* mdio_mux_multiplexer_switch_fn - This function is called by the mdio-mux
* layer when it thinks the mdio bus
* multiplexer needs to switch.
* @current_child: current value of the mux register.
* @desired_child: value of the 'reg' property of the target child MDIO node.
* @data: Private data used by this switch_fn passed to mdio_mux_init function
* via mdio_mux_init(.., .., .., .., data, ..).
*
* 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_multiplexer_switch_fn(int current_child, int desired_child,
void *data)
{
struct platform_device *pdev;
struct mdio_mux_multiplexer_state *s;
int ret = 0;
pdev = (struct platform_device *)data;
s = platform_get_drvdata(pdev);
if (!(current_child ^ desired_child))
return 0;
if (s->do_deselect)
ret = mux_control_deselect(s->muxc);
if (ret) {
dev_err(&pdev->dev, "mux_control_deselect failed in %s: %d\n",
__func__, ret);
return ret;
}
ret = mux_control_select(s->muxc, desired_child);
if (!ret) {
dev_dbg(&pdev->dev, "%s %d -> %d\n", __func__, current_child,
desired_child);
s->do_deselect = true;
} else {
s->do_deselect = false;
}
return ret;
}
static int mdio_mux_multiplexer_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct mdio_mux_multiplexer_state *s;
int ret = 0;
s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
s->muxc = devm_mux_control_get(dev, NULL);
if (IS_ERR(s->muxc)) {
ret = PTR_ERR(s->muxc);
if (ret != -EPROBE_DEFER)
dev_err(&pdev->dev, "Failed to get mux: %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, s);
ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
mdio_mux_multiplexer_switch_fn, &s->mux_handle,
pdev, NULL);
return ret;
}
static int mdio_mux_multiplexer_remove(struct platform_device *pdev)
{
struct mdio_mux_multiplexer_state *s = platform_get_drvdata(pdev);
mdio_mux_uninit(s->mux_handle);
if (s->do_deselect)
mux_control_deselect(s->muxc);
return 0;
}
static const struct of_device_id mdio_mux_multiplexer_match[] = {
{ .compatible = "mdio-mux-multiplexer", },
{},
};
MODULE_DEVICE_TABLE(of, mdio_mux_multiplexer_match);
static struct platform_driver mdio_mux_multiplexer_driver = {
.driver = {
.name = "mdio-mux-multiplexer",
.of_match_table = mdio_mux_multiplexer_match,
},
.probe = mdio_mux_multiplexer_probe,
.remove = mdio_mux_multiplexer_remove,
};
module_platform_driver(mdio_mux_multiplexer_driver);
MODULE_DESCRIPTION("MDIO bus multiplexer using kernel multiplexer subsystem");
MODULE_AUTHOR("Pankaj Bansal <pankaj.bansal@nxp.com>");
MODULE_LICENSE("GPL");
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