1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * General Purpose I2C multiplexer
4 *
5 * Copyright (C) 2017 Axentia Technologies AB
6 *
7 * Author: Peter Rosin <peda@axentia.se>
8 */
9
10#include <linux/i2c.h>
11#include <linux/i2c-mux.h>
12#include <linux/module.h>
13#include <linux/mux/consumer.h>
14#include <linux/of.h>
15#include <linux/platform_device.h>
16
17struct mux {
18	struct mux_control *control;
19
20	bool do_not_deselect;
21};
22
23static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
24{
25	struct mux *mux = i2c_mux_priv(muxc);
26	int ret;
27
28	ret = mux_control_select(mux->control, chan);
29	mux->do_not_deselect = ret < 0;
30
31	return ret;
32}
33
34static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
35{
36	struct mux *mux = i2c_mux_priv(muxc);
37
38	if (mux->do_not_deselect)
39		return 0;
40
41	return mux_control_deselect(mux->control);
42}
43
44static struct i2c_adapter *mux_parent_adapter(struct device *dev)
45{
46	struct device_node *np = dev->of_node;
47	struct device_node *parent_np;
48	struct i2c_adapter *parent;
49
50	parent_np = of_parse_phandle(np, "i2c-parent", 0);
51	if (!parent_np) {
52		dev_err(dev, "Cannot parse i2c-parent\n");
53		return ERR_PTR(-ENODEV);
54	}
55	parent = of_get_i2c_adapter_by_node(parent_np);
56	of_node_put(parent_np);
57	if (!parent)
58		return ERR_PTR(-EPROBE_DEFER);
59
60	return parent;
61}
62
63static const struct of_device_id i2c_mux_of_match[] = {
64	{ .compatible = "i2c-mux", },
65	{},
66};
67MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
68
69static int i2c_mux_probe(struct platform_device *pdev)
70{
71	struct device *dev = &pdev->dev;
72	struct device_node *np = dev->of_node;
73	struct device_node *child;
74	struct i2c_mux_core *muxc;
75	struct mux *mux;
76	struct i2c_adapter *parent;
77	int children;
78	int ret;
79
80	if (!np)
81		return -ENODEV;
82
83	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
84	if (!mux)
85		return -ENOMEM;
86
87	mux->control = devm_mux_control_get(dev, NULL);
88	if (IS_ERR(mux->control))
89		return dev_err_probe(dev, PTR_ERR(mux->control),
90				     "failed to get control-mux\n");
91
92	parent = mux_parent_adapter(dev);
93	if (IS_ERR(parent))
94		return dev_err_probe(dev, PTR_ERR(parent),
95				     "failed to get i2c-parent adapter\n");
96
97	children = of_get_child_count(np);
98
99	muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
100			     i2c_mux_select, i2c_mux_deselect);
101	if (!muxc) {
102		ret = -ENOMEM;
103		goto err_parent;
104	}
105	muxc->priv = mux;
106
107	platform_set_drvdata(pdev, muxc);
108
109	muxc->mux_locked = of_property_read_bool(np, "mux-locked");
110
111	for_each_child_of_node(np, child) {
112		u32 chan;
113
114		ret = of_property_read_u32(child, "reg", &chan);
115		if (ret < 0) {
116			dev_err(dev, "no reg property for node '%pOFn'\n",
117				child);
118			goto err_children;
119		}
120
121		if (chan >= mux_control_states(mux->control)) {
122			dev_err(dev, "invalid reg %u\n", chan);
123			ret = -EINVAL;
124			goto err_children;
125		}
126
127		ret = i2c_mux_add_adapter(muxc, 0, chan, 0);
128		if (ret)
129			goto err_children;
130	}
131
132	dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
133
134	return 0;
135
136err_children:
137	of_node_put(child);
138	i2c_mux_del_adapters(muxc);
139err_parent:
140	i2c_put_adapter(parent);
141
142	return ret;
143}
144
145static void i2c_mux_remove(struct platform_device *pdev)
146{
147	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
148
149	i2c_mux_del_adapters(muxc);
150	i2c_put_adapter(muxc->parent);
151}
152
153static struct platform_driver i2c_mux_driver = {
154	.probe	= i2c_mux_probe,
155	.remove_new = i2c_mux_remove,
156	.driver	= {
157		.name	= "i2c-mux-gpmux",
158		.of_match_table = i2c_mux_of_match,
159	},
160};
161module_platform_driver(i2c_mux_driver);
162
163MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
164MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
165MODULE_LICENSE("GPL v2");
166