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_device.h>
15 #include <linux/platform_device.h>
16 
17 struct mux {
18 	struct mux_control *control;
19 
20 	bool do_not_deselect;
21 };
22 
23 static 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 
34 static 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 
44 static 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_find_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 
63 static const struct of_device_id i2c_mux_of_match[] = {
64 	{ .compatible = "i2c-mux", },
65 	{},
66 };
67 MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
68 
69 static 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 
136 err_children:
137 	i2c_mux_del_adapters(muxc);
138 err_parent:
139 	i2c_put_adapter(parent);
140 
141 	return ret;
142 }
143 
144 static int i2c_mux_remove(struct platform_device *pdev)
145 {
146 	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
147 
148 	i2c_mux_del_adapters(muxc);
149 	i2c_put_adapter(muxc->parent);
150 
151 	return 0;
152 }
153 
154 static struct platform_driver i2c_mux_driver = {
155 	.probe	= i2c_mux_probe,
156 	.remove	= i2c_mux_remove,
157 	.driver	= {
158 		.name	= "i2c-mux-gpmux",
159 		.of_match_table = i2c_mux_of_match,
160 	},
161 };
162 module_platform_driver(i2c_mux_driver);
163 
164 MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
165 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
166 MODULE_LICENSE("GPL v2");
167