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Michael Lawnick08263742010-08-11 18:21:02 +02001/*
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>
David Daneybc454492012-04-12 14:14:23 -070027#include <linux/of.h>
28#include <linux/of_i2c.h>
Michael Lawnick08263742010-08-11 18:21:02 +020029
30/* multiplexer per channel data */
31struct i2c_mux_priv {
32 struct i2c_adapter adap;
33 struct i2c_algorithm algo;
34
35 struct i2c_adapter *parent;
David Daney5a3ecd52012-04-12 14:14:22 -070036 void *mux_priv; /* the mux chip/device */
Michael Lawnick08263742010-08-11 18:21:02 +020037 u32 chan_id; /* the channel id */
38
David Daney5a3ecd52012-04-12 14:14:22 -070039 int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
40 int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
Michael Lawnick08263742010-08-11 18:21:02 +020041};
42
43static 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
David Daney5a3ecd52012-04-12 14:14:22 -070052 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
Michael Lawnick08263742010-08-11 18:21:02 +020053 if (ret >= 0)
54 ret = parent->algo->master_xfer(parent, msgs, num);
55 if (priv->deselect)
David Daney5a3ecd52012-04-12 14:14:22 -070056 priv->deselect(parent, priv->mux_priv, priv->chan_id);
Michael Lawnick08263742010-08-11 18:21:02 +020057
58 return ret;
59}
60
61static 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
David Daney5a3ecd52012-04-12 14:14:22 -070072 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
Michael Lawnick08263742010-08-11 18:21:02 +020073 if (ret >= 0)
74 ret = parent->algo->smbus_xfer(parent, addr, flags,
75 read_write, command, size, data);
76 if (priv->deselect)
David Daney5a3ecd52012-04-12 14:14:22 -070077 priv->deselect(parent, priv->mux_priv, priv->chan_id);
Michael Lawnick08263742010-08-11 18:21:02 +020078
79 return ret;
80}
81
82/* Return the parent's functionality */
83static 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
Jean Delvareeee543e2012-10-05 22:23:51 +020091/* Return all parent classes, merged */
92static 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
Michael Lawnick08263742010-08-11 18:21:02 +0200104struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
David Daney5a3ecd52012-04-12 14:14:22 -0700105 struct device *mux_dev,
106 void *mux_priv, u32 force_nr, u32 chan_id,
Jean Delvareeee543e2012-10-05 22:23:51 +0200107 unsigned int class,
Michael Lawnick08263742010-08-11 18:21:02 +0200108 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;
David Daney5a3ecd52012-04-12 14:14:22 -0700122 priv->mux_priv = mux_priv;
Michael Lawnick08263742010-08-11 18:21:02 +0200123 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;
Michael Lawnick08263742010-08-11 18:21:02 +0200140 priv->adap.algo = &priv->algo;
141 priv->adap.algo_data = priv;
142 priv->adap.dev.parent = &parent->dev;
143
Jean Delvareeee543e2012-10-05 22:23:51 +0200144 /* 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
David Daneybc454492012-04-12 14:14:23 -0700152 /*
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", &reg);
162 if (ret)
163 continue;
164 if (chan_id == reg) {
165 priv->adap.dev.of_node = child;
166 break;
167 }
168 }
169 }
170
Michael Lawnick08263742010-08-11 18:21:02 +0200171 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
David Daneybc454492012-04-12 14:14:23 -0700188 of_i2c_register_devices(&priv->adap);
189
Michael Lawnick08263742010-08-11 18:21:02 +0200190 return &priv->adap;
191}
192EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
193
Lars-Peter Clausen51d95702013-03-09 08:16:49 +0000194void i2c_del_mux_adapter(struct i2c_adapter *adap)
Michael Lawnick08263742010-08-11 18:21:02 +0200195{
196 struct i2c_mux_priv *priv = adap->algo_data;
Michael Lawnick08263742010-08-11 18:21:02 +0200197
Lars-Peter Clausenbf51a8c2013-03-09 08:16:46 +0000198 i2c_del_adapter(adap);
Michael Lawnick08263742010-08-11 18:21:02 +0200199 kfree(priv);
Michael Lawnick08263742010-08-11 18:21:02 +0200200}
201EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
202
203MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
204MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
205MODULE_LICENSE("GPL v2");