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
i2c_mux_select(struct i2c_mux_core * muxc,u32 chan)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
i2c_mux_deselect(struct i2c_mux_core * muxc,u32 chan)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
mux_parent_adapter(struct device * dev)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
i2c_mux_probe(struct platform_device * pdev)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 '%s'\n",
124 child->name);
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
i2c_mux_remove(struct platform_device * pdev)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
