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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> | |
27 | ||
28 | /* multiplexer per channel data */ | |
29 | struct i2c_mux_priv { | |
30 | struct i2c_adapter adap; | |
31 | struct i2c_algorithm algo; | |
32 | ||
33 | struct i2c_adapter *parent; | |
34 | void *mux_dev; /* the mux chip/device */ | |
35 | u32 chan_id; /* the channel id */ | |
36 | ||
37 | int (*select)(struct i2c_adapter *, void *mux_dev, u32 chan_id); | |
38 | int (*deselect)(struct i2c_adapter *, void *mux_dev, u32 chan_id); | |
39 | }; | |
40 | ||
41 | static int i2c_mux_master_xfer(struct i2c_adapter *adap, | |
42 | struct i2c_msg msgs[], int num) | |
43 | { | |
44 | struct i2c_mux_priv *priv = adap->algo_data; | |
45 | struct i2c_adapter *parent = priv->parent; | |
46 | int ret; | |
47 | ||
48 | /* Switch to the right mux port and perform the transfer. */ | |
49 | ||
50 | ret = priv->select(parent, priv->mux_dev, priv->chan_id); | |
51 | if (ret >= 0) | |
52 | ret = parent->algo->master_xfer(parent, msgs, num); | |
53 | if (priv->deselect) | |
54 | priv->deselect(parent, priv->mux_dev, priv->chan_id); | |
55 | ||
56 | return ret; | |
57 | } | |
58 | ||
59 | static int i2c_mux_smbus_xfer(struct i2c_adapter *adap, | |
60 | u16 addr, unsigned short flags, | |
61 | char read_write, u8 command, | |
62 | int size, union i2c_smbus_data *data) | |
63 | { | |
64 | struct i2c_mux_priv *priv = adap->algo_data; | |
65 | struct i2c_adapter *parent = priv->parent; | |
66 | int ret; | |
67 | ||
68 | /* Select the right mux port and perform the transfer. */ | |
69 | ||
70 | ret = priv->select(parent, priv->mux_dev, priv->chan_id); | |
71 | if (ret >= 0) | |
72 | ret = parent->algo->smbus_xfer(parent, addr, flags, | |
73 | read_write, command, size, data); | |
74 | if (priv->deselect) | |
75 | priv->deselect(parent, priv->mux_dev, priv->chan_id); | |
76 | ||
77 | return ret; | |
78 | } | |
79 | ||
80 | /* Return the parent's functionality */ | |
81 | static u32 i2c_mux_functionality(struct i2c_adapter *adap) | |
82 | { | |
83 | struct i2c_mux_priv *priv = adap->algo_data; | |
84 | struct i2c_adapter *parent = priv->parent; | |
85 | ||
86 | return parent->algo->functionality(parent); | |
87 | } | |
88 | ||
89 | struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, | |
90 | void *mux_dev, u32 force_nr, u32 chan_id, | |
91 | int (*select) (struct i2c_adapter *, | |
92 | void *, u32), | |
93 | int (*deselect) (struct i2c_adapter *, | |
94 | void *, u32)) | |
95 | { | |
96 | struct i2c_mux_priv *priv; | |
97 | int ret; | |
98 | ||
99 | priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL); | |
100 | if (!priv) | |
101 | return NULL; | |
102 | ||
103 | /* Set up private adapter data */ | |
104 | priv->parent = parent; | |
105 | priv->mux_dev = mux_dev; | |
106 | priv->chan_id = chan_id; | |
107 | priv->select = select; | |
108 | priv->deselect = deselect; | |
109 | ||
110 | /* Need to do algo dynamically because we don't know ahead | |
111 | * of time what sort of physical adapter we'll be dealing with. | |
112 | */ | |
113 | if (parent->algo->master_xfer) | |
114 | priv->algo.master_xfer = i2c_mux_master_xfer; | |
115 | if (parent->algo->smbus_xfer) | |
116 | priv->algo.smbus_xfer = i2c_mux_smbus_xfer; | |
117 | priv->algo.functionality = i2c_mux_functionality; | |
118 | ||
119 | /* Now fill out new adapter structure */ | |
120 | snprintf(priv->adap.name, sizeof(priv->adap.name), | |
121 | "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id); | |
122 | priv->adap.owner = THIS_MODULE; | |
0826374b ML |
123 | priv->adap.algo = &priv->algo; |
124 | priv->adap.algo_data = priv; | |
125 | priv->adap.dev.parent = &parent->dev; | |
126 | ||
127 | if (force_nr) { | |
128 | priv->adap.nr = force_nr; | |
129 | ret = i2c_add_numbered_adapter(&priv->adap); | |
130 | } else { | |
131 | ret = i2c_add_adapter(&priv->adap); | |
132 | } | |
133 | if (ret < 0) { | |
134 | dev_err(&parent->dev, | |
135 | "failed to add mux-adapter (error=%d)\n", | |
136 | ret); | |
137 | kfree(priv); | |
138 | return NULL; | |
139 | } | |
140 | ||
141 | dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", | |
142 | i2c_adapter_id(&priv->adap)); | |
143 | ||
144 | return &priv->adap; | |
145 | } | |
146 | EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); | |
147 | ||
148 | int i2c_del_mux_adapter(struct i2c_adapter *adap) | |
149 | { | |
150 | struct i2c_mux_priv *priv = adap->algo_data; | |
151 | int ret; | |
152 | ||
153 | ret = i2c_del_adapter(adap); | |
154 | if (ret < 0) | |
155 | return ret; | |
156 | kfree(priv); | |
157 | ||
158 | return 0; | |
159 | } | |
160 | EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); | |
161 | ||
162 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); | |
163 | MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); | |
164 | MODULE_LICENSE("GPL v2"); |