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/mdio-mux.h>
8#include <linux/module.h>
9#include <linux/mux/consumer.h>
10#include <linux/platform_device.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(mux: 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(mux: s->muxc, state: 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(dev: &pdev->dev, size: sizeof(*s), GFP_KERNEL);
71 if (!s)
72 return -ENOMEM;
73
74 s->muxc = devm_mux_control_get(dev, NULL);
75 if (IS_ERR(ptr: s->muxc))
76 return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: s->muxc),
77 fmt: "Failed to get mux\n");
78
79 platform_set_drvdata(pdev, data: s);
80
81 ret = mdio_mux_init(dev: &pdev->dev, mux_node: pdev->dev.of_node,
82 switch_fn: mdio_mux_multiplexer_switch_fn, mux_handle: &s->mux_handle,
83 data: pdev, NULL);
84
85 return ret;
86}
87
88static void mdio_mux_multiplexer_remove(struct platform_device *pdev)
89{
90 struct mdio_mux_multiplexer_state *s = platform_get_drvdata(pdev);
91
92 mdio_mux_uninit(mux_handle: s->mux_handle);
93
94 if (s->do_deselect)
95 mux_control_deselect(mux: s->muxc);
96}
97
98static const struct of_device_id mdio_mux_multiplexer_match[] = {
99 { .compatible = "mdio-mux-multiplexer", },
100 {},
101};
102MODULE_DEVICE_TABLE(of, mdio_mux_multiplexer_match);
103
104static struct platform_driver mdio_mux_multiplexer_driver = {
105 .driver = {
106 .name = "mdio-mux-multiplexer",
107 .of_match_table = mdio_mux_multiplexer_match,
108 },
109 .probe = mdio_mux_multiplexer_probe,
110 .remove_new = mdio_mux_multiplexer_remove,
111};
112
113module_platform_driver(mdio_mux_multiplexer_driver);
114
115MODULE_DESCRIPTION("MDIO bus multiplexer using kernel multiplexer subsystem");
116MODULE_AUTHOR("Pankaj Bansal <pankaj.bansal@nxp.com>");
117MODULE_LICENSE("GPL");
118

source code of linux/drivers/net/mdio/mdio-mux-multiplexer.c