1 /*
2  * General Purpose I2C multiplexer
3  *
4  * Copyright (C) 2017 Axentia Technologies AB
5  *
6  * Author: Peter Rosin <peda@axentia.se>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12 
13 #include <linux/i2c.h>
14 #include <linux/i2c-mux.h>
15 #include <linux/module.h>
16 #include <linux/mux/consumer.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 
20 struct mux {
21 	struct mux_control *control;
22 
23 	bool do_not_deselect;
24 };
25 
26 static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
27 {
28 	struct mux *mux = i2c_mux_priv(muxc);
29 	int ret;
30 
31 	ret = mux_control_select(mux->control, chan);
32 	mux->do_not_deselect = ret < 0;
33 
34 	return ret;
35 }
36 
37 static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
38 {
39 	struct mux *mux = i2c_mux_priv(muxc);
40 
41 	if (mux->do_not_deselect)
42 		return 0;
43 
44 	return mux_control_deselect(mux->control);
45 }
46 
47 static struct i2c_adapter *mux_parent_adapter(struct device *dev)
48 {
49 	struct device_node *np = dev->of_node;
50 	struct device_node *parent_np;
51 	struct i2c_adapter *parent;
52 
53 	parent_np = of_parse_phandle(np, "i2c-parent", 0);
54 	if (!parent_np) {
55 		dev_err(dev, "Cannot parse i2c-parent\n");
56 		return ERR_PTR(-ENODEV);
57 	}
58 	parent = of_find_i2c_adapter_by_node(parent_np);
59 	of_node_put(parent_np);
60 	if (!parent)
61 		return ERR_PTR(-EPROBE_DEFER);
62 
63 	return parent;
64 }
65 
66 static const struct of_device_id i2c_mux_of_match[] = {
67 	{ .compatible = "i2c-mux", },
68 	{},
69 };
70 MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
71 
72 static int i2c_mux_probe(struct platform_device *pdev)
73 {
74 	struct device *dev = &pdev->dev;
75 	struct device_node *np = dev->of_node;
76 	struct device_node *child;
77 	struct i2c_mux_core *muxc;
78 	struct mux *mux;
79 	struct i2c_adapter *parent;
80 	int children;
81 	int ret;
82 
83 	if (!np)
84 		return -ENODEV;
85 
86 	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
87 	if (!mux)
88 		return -ENOMEM;
89 
90 	mux->control = devm_mux_control_get(dev, NULL);
91 	if (IS_ERR(mux->control)) {
92 		if (PTR_ERR(mux->control) != -EPROBE_DEFER)
93 			dev_err(dev, "failed to get control-mux\n");
94 		return PTR_ERR(mux->control);
95 	}
96 
97 	parent = mux_parent_adapter(dev);
98 	if (IS_ERR(parent)) {
99 		if (PTR_ERR(parent) != -EPROBE_DEFER)
100 			dev_err(dev, "failed to get i2c-parent adapter\n");
101 		return PTR_ERR(parent);
102 	}
103 
104 	children = of_get_child_count(np);
105 
106 	muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
107 			     i2c_mux_select, i2c_mux_deselect);
108 	if (!muxc) {
109 		ret = -ENOMEM;
110 		goto err_parent;
111 	}
112 	muxc->priv = mux;
113 
114 	platform_set_drvdata(pdev, muxc);
115 
116 	muxc->mux_locked = of_property_read_bool(np, "mux-locked");
117 
118 	for_each_child_of_node(np, child) {
119 		u32 chan;
120 
121 		ret = of_property_read_u32(child, "reg", &chan);
122 		if (ret < 0) {
123 			dev_err(dev, "no reg property for node '%pOFn'\n",
124 				child);
125 			goto err_children;
126 		}
127 
128 		if (chan >= mux_control_states(mux->control)) {
129 			dev_err(dev, "invalid reg %u\n", chan);
130 			ret = -EINVAL;
131 			goto err_children;
132 		}
133 
134 		ret = i2c_mux_add_adapter(muxc, 0, chan, 0);
135 		if (ret)
136 			goto err_children;
137 	}
138 
139 	dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
140 
141 	return 0;
142 
143 err_children:
144 	i2c_mux_del_adapters(muxc);
145 err_parent:
146 	i2c_put_adapter(parent);
147 
148 	return ret;
149 }
150 
151 static int i2c_mux_remove(struct platform_device *pdev)
152 {
153 	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
154 
155 	i2c_mux_del_adapters(muxc);
156 	i2c_put_adapter(muxc->parent);
157 
158 	return 0;
159 }
160 
161 static struct platform_driver i2c_mux_driver = {
162 	.probe	= i2c_mux_probe,
163 	.remove	= i2c_mux_remove,
164 	.driver	= {
165 		.name	= "i2c-mux-gpmux",
166 		.of_match_table = i2c_mux_of_match,
167 	},
168 };
169 module_platform_driver(i2c_mux_driver);
170 
171 MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
172 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
173 MODULE_LICENSE("GPL v2");
174