1// SPDX-License-Identifier: GPL-2.0+
  2/* MDIO bus multiplexer using kernel multiplexer subsystem
  3 *
  4 * Copyright 2019 NXP
  5 */
  6
  7#include <linux/platform_device.h>
  8#include <linux/mdio-mux.h>
  9#include <linux/module.h>
 10#include <linux/mux/consumer.h>
 11
 12struct mdio_mux_multiplexer_state {
 13	struct mux_control *muxc;
 14	bool do_deselect;
 15	void *mux_handle;
 16};
 17
 18/**
 19 * mdio_mux_multiplexer_switch_fn - This function is called by the mdio-mux
 20 *                                  layer when it thinks the mdio bus
 21 *                                  multiplexer needs to switch.
 22 * @current_child:  current value of the mux register.
 23 * @desired_child: value of the 'reg' property of the target child MDIO node.
 24 * @data: Private data used by this switch_fn passed to mdio_mux_init function
 25 *        via mdio_mux_init(.., .., .., .., data, ..).
 26 *
 27 * The first time this function is called, current_child == -1.
 28 * If current_child == desired_child, then the mux is already set to the
 29 * correct bus.
 30 */
 31static int mdio_mux_multiplexer_switch_fn(int current_child, int desired_child,
 32					  void *data)
 33{
 34	struct platform_device *pdev;
 35	struct mdio_mux_multiplexer_state *s;
 36	int ret = 0;
 37
 38	pdev = (struct platform_device *)data;
 39	s = platform_get_drvdata(pdev);
 40
 41	if (!(current_child ^ desired_child))
 42		return 0;
 43
 44	if (s->do_deselect)
 45		ret = mux_control_deselect(s->muxc);
 46	if (ret) {
 47		dev_err(&pdev->dev, "mux_control_deselect failed in %s: %d\n",
 48			__func__, ret);
 49		return ret;
 50	}
 51
 52	ret =  mux_control_select(s->muxc, desired_child);
 53	if (!ret) {
 54		dev_dbg(&pdev->dev, "%s %d -> %d\n", __func__, current_child,
 55			desired_child);
 56		s->do_deselect = true;
 57	} else {
 58		s->do_deselect = false;
 59	}
 60
 61	return ret;
 62}
 63
 64static int mdio_mux_multiplexer_probe(struct platform_device *pdev)
 65{
 66	struct device *dev = &pdev->dev;
 67	struct mdio_mux_multiplexer_state *s;
 68	int ret = 0;
 69
 70	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
 71	if (!s)
 72		return -ENOMEM;
 73
 74	s->muxc = devm_mux_control_get(dev, NULL);
 75	if (IS_ERR(s->muxc)) {
 76		ret = PTR_ERR(s->muxc);
 77		if (ret != -EPROBE_DEFER)
 78			dev_err(&pdev->dev, "Failed to get mux: %d\n", ret);
 79		return ret;
 80	}
 81
 82	platform_set_drvdata(pdev, s);
 83
 84	ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
 85			    mdio_mux_multiplexer_switch_fn, &s->mux_handle,
 86			    pdev, NULL);
 87
 88	return ret;
 89}
 90
 91static int mdio_mux_multiplexer_remove(struct platform_device *pdev)
 92{
 93	struct mdio_mux_multiplexer_state *s = platform_get_drvdata(pdev);
 94
 95	mdio_mux_uninit(s->mux_handle);
 96
 97	if (s->do_deselect)
 98		mux_control_deselect(s->muxc);
 99
100	return 0;
101}
102
103static const struct of_device_id mdio_mux_multiplexer_match[] = {
104	{ .compatible = "mdio-mux-multiplexer", },
105	{},
106};
107MODULE_DEVICE_TABLE(of, mdio_mux_multiplexer_match);
108
109static struct platform_driver mdio_mux_multiplexer_driver = {
110	.driver = {
111		.name		= "mdio-mux-multiplexer",
112		.of_match_table	= mdio_mux_multiplexer_match,
113	},
114	.probe		= mdio_mux_multiplexer_probe,
115	.remove		= mdio_mux_multiplexer_remove,
116};
117
118module_platform_driver(mdio_mux_multiplexer_driver);
119
120MODULE_DESCRIPTION("MDIO bus multiplexer using kernel multiplexer subsystem");
121MODULE_AUTHOR("Pankaj Bansal <pankaj.bansal@nxp.com>");
122MODULE_LICENSE("GPL");