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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>
Michael Lawnick08263742010-08-11 18:21:02 +020028
29/* multiplexer per channel data */
30struct i2c_mux_priv {
31 struct i2c_adapter adap;
32 struct i2c_algorithm algo;
33
34 struct i2c_adapter *parent;
Wolfram Sang13377842015-04-23 10:29:09 +020035 struct device *mux_dev;
36 void *mux_priv;
37 u32 chan_id;
Michael Lawnick08263742010-08-11 18:21:02 +020038
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)
Alexander Sverdline766f332015-06-12 14:40:37 +020054 ret = __i2c_transfer(parent, msgs, num);
Michael Lawnick08263742010-08-11 18:21:02 +020055 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;
Gerlando Falautoc9449af2014-11-13 14:39:56 +0100114 char symlink_name[20];
Michael Lawnick08263742010-08-11 18:21:02 +0200115 int ret;
116
117 priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
118 if (!priv)
119 return NULL;
120
121 /* Set up private adapter data */
122 priv->parent = parent;
Wolfram Sang13377842015-04-23 10:29:09 +0200123 priv->mux_dev = mux_dev;
David Daney5a3ecd52012-04-12 14:14:22 -0700124 priv->mux_priv = mux_priv;
Michael Lawnick08263742010-08-11 18:21:02 +0200125 priv->chan_id = chan_id;
126 priv->select = select;
127 priv->deselect = deselect;
128
129 /* Need to do algo dynamically because we don't know ahead
130 * of time what sort of physical adapter we'll be dealing with.
131 */
132 if (parent->algo->master_xfer)
133 priv->algo.master_xfer = i2c_mux_master_xfer;
134 if (parent->algo->smbus_xfer)
135 priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
136 priv->algo.functionality = i2c_mux_functionality;
137
138 /* Now fill out new adapter structure */
139 snprintf(priv->adap.name, sizeof(priv->adap.name),
140 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
141 priv->adap.owner = THIS_MODULE;
Michael Lawnick08263742010-08-11 18:21:02 +0200142 priv->adap.algo = &priv->algo;
143 priv->adap.algo_data = priv;
144 priv->adap.dev.parent = &parent->dev;
Elie De Brauwer2212a852013-12-09 19:48:28 +0100145 priv->adap.retries = parent->retries;
146 priv->adap.timeout = parent->timeout;
Alexander Sverdlindc362d52015-06-12 14:41:16 +0200147 priv->adap.quirks = parent->quirks;
Michael Lawnick08263742010-08-11 18:21:02 +0200148
Jean Delvareeee543e2012-10-05 22:23:51 +0200149 /* Sanity check on class */
150 if (i2c_mux_parent_classes(parent) & class)
151 dev_err(&parent->dev,
152 "Segment %d behind mux can't share classes with ancestors\n",
153 chan_id);
154 else
155 priv->adap.class = class;
156
David Daneybc454492012-04-12 14:14:23 -0700157 /*
158 * Try to populate the mux adapter's of_node, expands to
159 * nothing if !CONFIG_OF.
160 */
161 if (mux_dev->of_node) {
162 struct device_node *child;
163 u32 reg;
164
165 for_each_child_of_node(mux_dev->of_node, child) {
166 ret = of_property_read_u32(child, "reg", &reg);
167 if (ret)
168 continue;
169 if (chan_id == reg) {
170 priv->adap.dev.of_node = child;
171 break;
172 }
173 }
174 }
175
Michael Lawnick08263742010-08-11 18:21:02 +0200176 if (force_nr) {
177 priv->adap.nr = force_nr;
178 ret = i2c_add_numbered_adapter(&priv->adap);
179 } else {
180 ret = i2c_add_adapter(&priv->adap);
181 }
182 if (ret < 0) {
183 dev_err(&parent->dev,
184 "failed to add mux-adapter (error=%d)\n",
185 ret);
186 kfree(priv);
187 return NULL;
188 }
189
Wolfram Sang51cf3b02014-11-13 14:39:55 +0100190 WARN(sysfs_create_link(&priv->adap.dev.kobj, &mux_dev->kobj, "mux_device"),
191 "can't create symlink to mux device\n");
192
Gerlando Falautoc9449af2014-11-13 14:39:56 +0100193 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
194 WARN(sysfs_create_link(&mux_dev->kobj, &priv->adap.dev.kobj, symlink_name),
195 "can't create symlink for channel %u\n", chan_id);
Michael Lawnick08263742010-08-11 18:21:02 +0200196 dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
197 i2c_adapter_id(&priv->adap));
198
Michael Lawnick08263742010-08-11 18:21:02 +0200199 return &priv->adap;
200}
201EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
202
Lars-Peter Clausen51d95702013-03-09 08:16:49 +0000203void i2c_del_mux_adapter(struct i2c_adapter *adap)
Michael Lawnick08263742010-08-11 18:21:02 +0200204{
205 struct i2c_mux_priv *priv = adap->algo_data;
Gerlando Falautoc9449af2014-11-13 14:39:56 +0100206 char symlink_name[20];
207
208 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", priv->chan_id);
Wolfram Sang13377842015-04-23 10:29:09 +0200209 sysfs_remove_link(&priv->mux_dev->kobj, symlink_name);
Michael Lawnick08263742010-08-11 18:21:02 +0200210
Wolfram Sang51cf3b02014-11-13 14:39:55 +0100211 sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
Lars-Peter Clausenbf51a8c2013-03-09 08:16:46 +0000212 i2c_del_adapter(adap);
Michael Lawnick08263742010-08-11 18:21:02 +0200213 kfree(priv);
Michael Lawnick08263742010-08-11 18:21:02 +0200214}
215EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
216
217MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
218MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
219MODULE_LICENSE("GPL v2");