2 * Multiplexed I2C bus driver.
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>
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).
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>
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.
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>
28 #include <linux/of_i2c.h>
30 /* multiplexer per channel data */
32 struct i2c_adapter adap
;
33 struct i2c_algorithm algo
;
35 struct i2c_adapter
*parent
;
36 void *mux_priv
; /* the mux chip/device */
37 u32 chan_id
; /* the channel id */
39 int (*select
)(struct i2c_adapter
*, void *mux_priv
, u32 chan_id
);
40 int (*deselect
)(struct i2c_adapter
*, void *mux_priv
, u32 chan_id
);
43 static int i2c_mux_master_xfer(struct i2c_adapter
*adap
,
44 struct i2c_msg msgs
[], int num
)
46 struct i2c_mux_priv
*priv
= adap
->algo_data
;
47 struct i2c_adapter
*parent
= priv
->parent
;
50 /* Switch to the right mux port and perform the transfer. */
52 ret
= priv
->select(parent
, priv
->mux_priv
, priv
->chan_id
);
54 ret
= parent
->algo
->master_xfer(parent
, msgs
, num
);
56 priv
->deselect(parent
, priv
->mux_priv
, priv
->chan_id
);
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
)
66 struct i2c_mux_priv
*priv
= adap
->algo_data
;
67 struct i2c_adapter
*parent
= priv
->parent
;
70 /* Select the right mux port and perform the transfer. */
72 ret
= priv
->select(parent
, priv
->mux_priv
, priv
->chan_id
);
74 ret
= parent
->algo
->smbus_xfer(parent
, addr
, flags
,
75 read_write
, command
, size
, data
);
77 priv
->deselect(parent
, priv
->mux_priv
, priv
->chan_id
);
82 /* Return the parent's functionality */
83 static u32
i2c_mux_functionality(struct i2c_adapter
*adap
)
85 struct i2c_mux_priv
*priv
= adap
->algo_data
;
86 struct i2c_adapter
*parent
= priv
->parent
;
88 return parent
->algo
->functionality(parent
);
91 struct i2c_adapter
*i2c_add_mux_adapter(struct i2c_adapter
*parent
,
92 struct device
*mux_dev
,
93 void *mux_priv
, u32 force_nr
, u32 chan_id
,
94 int (*select
) (struct i2c_adapter
*,
96 int (*deselect
) (struct i2c_adapter
*,
99 struct i2c_mux_priv
*priv
;
102 priv
= kzalloc(sizeof(struct i2c_mux_priv
), GFP_KERNEL
);
106 /* Set up private adapter data */
107 priv
->parent
= parent
;
108 priv
->mux_priv
= mux_priv
;
109 priv
->chan_id
= chan_id
;
110 priv
->select
= select
;
111 priv
->deselect
= deselect
;
113 /* Need to do algo dynamically because we don't know ahead
114 * of time what sort of physical adapter we'll be dealing with.
116 if (parent
->algo
->master_xfer
)
117 priv
->algo
.master_xfer
= i2c_mux_master_xfer
;
118 if (parent
->algo
->smbus_xfer
)
119 priv
->algo
.smbus_xfer
= i2c_mux_smbus_xfer
;
120 priv
->algo
.functionality
= i2c_mux_functionality
;
122 /* Now fill out new adapter structure */
123 snprintf(priv
->adap
.name
, sizeof(priv
->adap
.name
),
124 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent
), chan_id
);
125 priv
->adap
.owner
= THIS_MODULE
;
126 priv
->adap
.algo
= &priv
->algo
;
127 priv
->adap
.algo_data
= priv
;
128 priv
->adap
.dev
.parent
= &parent
->dev
;
131 * Try to populate the mux adapter's of_node, expands to
132 * nothing if !CONFIG_OF.
134 if (mux_dev
->of_node
) {
135 struct device_node
*child
;
138 for_each_child_of_node(mux_dev
->of_node
, child
) {
139 ret
= of_property_read_u32(child
, "reg", ®
);
142 if (chan_id
== reg
) {
143 priv
->adap
.dev
.of_node
= child
;
150 priv
->adap
.nr
= force_nr
;
151 ret
= i2c_add_numbered_adapter(&priv
->adap
);
153 ret
= i2c_add_adapter(&priv
->adap
);
156 dev_err(&parent
->dev
,
157 "failed to add mux-adapter (error=%d)\n",
163 dev_info(&parent
->dev
, "Added multiplexed i2c bus %d\n",
164 i2c_adapter_id(&priv
->adap
));
166 of_i2c_register_devices(&priv
->adap
);
170 EXPORT_SYMBOL_GPL(i2c_add_mux_adapter
);
172 int i2c_del_mux_adapter(struct i2c_adapter
*adap
)
174 struct i2c_mux_priv
*priv
= adap
->algo_data
;
177 ret
= i2c_del_adapter(adap
);
184 EXPORT_SYMBOL_GPL(i2c_del_mux_adapter
);
186 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
187 MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
188 MODULE_LICENSE("GPL v2");