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0826374b ML |
1 | /* |
2 | * Multiplexed I2C bus driver. | |
3 | * | |
4 | * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it> | |
5 | * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it> | |
6 | * Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com> | |
7 | * | |
8 | * Simplifies access to complex multiplexed I2C bus topologies, by presenting | |
9 | * each multiplexed bus segment as an additional I2C adapter. | |
10 | * Supports multi-level mux'ing (mux behind a mux). | |
11 | * | |
12 | * Based on: | |
13 | * i2c-virt.c from Kumar Gala <galak@kernel.crashing.org> | |
14 | * i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc. | |
15 | * i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com> | |
16 | * | |
17 | * This file is licensed under the terms of the GNU General Public | |
18 | * License version 2. This program is licensed "as is" without any | |
19 | * warranty of any kind, whether express or implied. | |
20 | */ | |
21 | ||
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/slab.h> | |
25 | #include <linux/i2c.h> | |
26 | #include <linux/i2c-mux.h> | |
bc45449b DD |
27 | #include <linux/of.h> |
28 | #include <linux/of_i2c.h> | |
0826374b ML |
29 | |
30 | /* multiplexer per channel data */ | |
31 | struct i2c_mux_priv { | |
32 | struct i2c_adapter adap; | |
33 | struct i2c_algorithm algo; | |
34 | ||
35 | struct i2c_adapter *parent; | |
5a3ecd5f | 36 | void *mux_priv; /* the mux chip/device */ |
0826374b ML |
37 | u32 chan_id; /* the channel id */ |
38 | ||
5a3ecd5f DD |
39 | int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id); |
40 | int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id); | |
0826374b ML |
41 | }; |
42 | ||
43 | static int i2c_mux_master_xfer(struct i2c_adapter *adap, | |
44 | struct i2c_msg msgs[], int num) | |
45 | { | |
46 | struct i2c_mux_priv *priv = adap->algo_data; | |
47 | struct i2c_adapter *parent = priv->parent; | |
48 | int ret; | |
49 | ||
50 | /* Switch to the right mux port and perform the transfer. */ | |
51 | ||
5a3ecd5f | 52 | ret = priv->select(parent, priv->mux_priv, priv->chan_id); |
0826374b ML |
53 | if (ret >= 0) |
54 | ret = parent->algo->master_xfer(parent, msgs, num); | |
55 | if (priv->deselect) | |
5a3ecd5f | 56 | priv->deselect(parent, priv->mux_priv, priv->chan_id); |
0826374b ML |
57 | |
58 | return ret; | |
59 | } | |
60 | ||
61 | static int i2c_mux_smbus_xfer(struct i2c_adapter *adap, | |
62 | u16 addr, unsigned short flags, | |
63 | char read_write, u8 command, | |
64 | int size, union i2c_smbus_data *data) | |
65 | { | |
66 | struct i2c_mux_priv *priv = adap->algo_data; | |
67 | struct i2c_adapter *parent = priv->parent; | |
68 | int ret; | |
69 | ||
70 | /* Select the right mux port and perform the transfer. */ | |
71 | ||
5a3ecd5f | 72 | ret = priv->select(parent, priv->mux_priv, priv->chan_id); |
0826374b ML |
73 | if (ret >= 0) |
74 | ret = parent->algo->smbus_xfer(parent, addr, flags, | |
75 | read_write, command, size, data); | |
76 | if (priv->deselect) | |
5a3ecd5f | 77 | priv->deselect(parent, priv->mux_priv, priv->chan_id); |
0826374b ML |
78 | |
79 | return ret; | |
80 | } | |
81 | ||
82 | /* Return the parent's functionality */ | |
83 | static u32 i2c_mux_functionality(struct i2c_adapter *adap) | |
84 | { | |
85 | struct i2c_mux_priv *priv = adap->algo_data; | |
86 | struct i2c_adapter *parent = priv->parent; | |
87 | ||
88 | return parent->algo->functionality(parent); | |
89 | } | |
90 | ||
eee543e8 JD |
91 | /* Return all parent classes, merged */ |
92 | static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent) | |
93 | { | |
94 | unsigned int class = 0; | |
95 | ||
96 | do { | |
97 | class |= parent->class; | |
98 | parent = i2c_parent_is_i2c_adapter(parent); | |
99 | } while (parent); | |
100 | ||
101 | return class; | |
102 | } | |
103 | ||
0826374b | 104 | struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, |
5a3ecd5f DD |
105 | struct device *mux_dev, |
106 | void *mux_priv, u32 force_nr, u32 chan_id, | |
eee543e8 | 107 | unsigned int class, |
0826374b ML |
108 | int (*select) (struct i2c_adapter *, |
109 | void *, u32), | |
110 | int (*deselect) (struct i2c_adapter *, | |
111 | void *, u32)) | |
112 | { | |
113 | struct i2c_mux_priv *priv; | |
114 | int ret; | |
115 | ||
116 | priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL); | |
117 | if (!priv) | |
118 | return NULL; | |
119 | ||
120 | /* Set up private adapter data */ | |
121 | priv->parent = parent; | |
5a3ecd5f | 122 | priv->mux_priv = mux_priv; |
0826374b ML |
123 | priv->chan_id = chan_id; |
124 | priv->select = select; | |
125 | priv->deselect = deselect; | |
126 | ||
127 | /* Need to do algo dynamically because we don't know ahead | |
128 | * of time what sort of physical adapter we'll be dealing with. | |
129 | */ | |
130 | if (parent->algo->master_xfer) | |
131 | priv->algo.master_xfer = i2c_mux_master_xfer; | |
132 | if (parent->algo->smbus_xfer) | |
133 | priv->algo.smbus_xfer = i2c_mux_smbus_xfer; | |
134 | priv->algo.functionality = i2c_mux_functionality; | |
135 | ||
136 | /* Now fill out new adapter structure */ | |
137 | snprintf(priv->adap.name, sizeof(priv->adap.name), | |
138 | "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id); | |
139 | priv->adap.owner = THIS_MODULE; | |
0826374b ML |
140 | priv->adap.algo = &priv->algo; |
141 | priv->adap.algo_data = priv; | |
142 | priv->adap.dev.parent = &parent->dev; | |
143 | ||
eee543e8 JD |
144 | /* Sanity check on class */ |
145 | if (i2c_mux_parent_classes(parent) & class) | |
146 | dev_err(&parent->dev, | |
147 | "Segment %d behind mux can't share classes with ancestors\n", | |
148 | chan_id); | |
149 | else | |
150 | priv->adap.class = class; | |
151 | ||
bc45449b DD |
152 | /* |
153 | * Try to populate the mux adapter's of_node, expands to | |
154 | * nothing if !CONFIG_OF. | |
155 | */ | |
156 | if (mux_dev->of_node) { | |
157 | struct device_node *child; | |
158 | u32 reg; | |
159 | ||
160 | for_each_child_of_node(mux_dev->of_node, child) { | |
161 | ret = of_property_read_u32(child, "reg", ®); | |
162 | if (ret) | |
163 | continue; | |
164 | if (chan_id == reg) { | |
165 | priv->adap.dev.of_node = child; | |
166 | break; | |
167 | } | |
168 | } | |
169 | } | |
170 | ||
0826374b ML |
171 | if (force_nr) { |
172 | priv->adap.nr = force_nr; | |
173 | ret = i2c_add_numbered_adapter(&priv->adap); | |
174 | } else { | |
175 | ret = i2c_add_adapter(&priv->adap); | |
176 | } | |
177 | if (ret < 0) { | |
178 | dev_err(&parent->dev, | |
179 | "failed to add mux-adapter (error=%d)\n", | |
180 | ret); | |
181 | kfree(priv); | |
182 | return NULL; | |
183 | } | |
184 | ||
185 | dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", | |
186 | i2c_adapter_id(&priv->adap)); | |
187 | ||
bc45449b DD |
188 | of_i2c_register_devices(&priv->adap); |
189 | ||
0826374b ML |
190 | return &priv->adap; |
191 | } | |
192 | EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); | |
193 | ||
51d95709 | 194 | void i2c_del_mux_adapter(struct i2c_adapter *adap) |
0826374b ML |
195 | { |
196 | struct i2c_mux_priv *priv = adap->algo_data; | |
0826374b | 197 | |
bf51a8c5 | 198 | i2c_del_adapter(adap); |
0826374b | 199 | kfree(priv); |
0826374b ML |
200 | } |
201 | EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); | |
202 | ||
203 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); | |
204 | MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); | |
205 | MODULE_LICENSE("GPL v2"); |