Loading...
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 */
29struct 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
41static 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
59static 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 */
81static 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
89struct 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;
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}
146EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
147
148int 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}
160EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
161
162MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
163MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
164MODULE_LICENSE("GPL v2");
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#include <linux/of.h>
28
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;
35 void *mux_priv; /* the mux chip/device */
36 u32 chan_id; /* the channel id */
37
38 int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
39 int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
40};
41
42static int i2c_mux_master_xfer(struct i2c_adapter *adap,
43 struct i2c_msg msgs[], int num)
44{
45 struct i2c_mux_priv *priv = adap->algo_data;
46 struct i2c_adapter *parent = priv->parent;
47 int ret;
48
49 /* Switch to the right mux port and perform the transfer. */
50
51 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
52 if (ret >= 0)
53 ret = parent->algo->master_xfer(parent, msgs, num);
54 if (priv->deselect)
55 priv->deselect(parent, priv->mux_priv, priv->chan_id);
56
57 return ret;
58}
59
60static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
61 u16 addr, unsigned short flags,
62 char read_write, u8 command,
63 int size, union i2c_smbus_data *data)
64{
65 struct i2c_mux_priv *priv = adap->algo_data;
66 struct i2c_adapter *parent = priv->parent;
67 int ret;
68
69 /* Select the right mux port and perform the transfer. */
70
71 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
72 if (ret >= 0)
73 ret = parent->algo->smbus_xfer(parent, addr, flags,
74 read_write, command, size, data);
75 if (priv->deselect)
76 priv->deselect(parent, priv->mux_priv, priv->chan_id);
77
78 return ret;
79}
80
81/* Return the parent's functionality */
82static u32 i2c_mux_functionality(struct i2c_adapter *adap)
83{
84 struct i2c_mux_priv *priv = adap->algo_data;
85 struct i2c_adapter *parent = priv->parent;
86
87 return parent->algo->functionality(parent);
88}
89
90/* Return all parent classes, merged */
91static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
92{
93 unsigned int class = 0;
94
95 do {
96 class |= parent->class;
97 parent = i2c_parent_is_i2c_adapter(parent);
98 } while (parent);
99
100 return class;
101}
102
103struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
104 struct device *mux_dev,
105 void *mux_priv, u32 force_nr, u32 chan_id,
106 unsigned int class,
107 int (*select) (struct i2c_adapter *,
108 void *, u32),
109 int (*deselect) (struct i2c_adapter *,
110 void *, u32))
111{
112 struct i2c_mux_priv *priv;
113 int ret;
114
115 priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
116 if (!priv)
117 return NULL;
118
119 /* Set up private adapter data */
120 priv->parent = parent;
121 priv->mux_priv = mux_priv;
122 priv->chan_id = chan_id;
123 priv->select = select;
124 priv->deselect = deselect;
125
126 /* Need to do algo dynamically because we don't know ahead
127 * of time what sort of physical adapter we'll be dealing with.
128 */
129 if (parent->algo->master_xfer)
130 priv->algo.master_xfer = i2c_mux_master_xfer;
131 if (parent->algo->smbus_xfer)
132 priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
133 priv->algo.functionality = i2c_mux_functionality;
134
135 /* Now fill out new adapter structure */
136 snprintf(priv->adap.name, sizeof(priv->adap.name),
137 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
138 priv->adap.owner = THIS_MODULE;
139 priv->adap.algo = &priv->algo;
140 priv->adap.algo_data = priv;
141 priv->adap.dev.parent = &parent->dev;
142 priv->adap.retries = parent->retries;
143 priv->adap.timeout = parent->timeout;
144
145 /* Sanity check on class */
146 if (i2c_mux_parent_classes(parent) & class)
147 dev_err(&parent->dev,
148 "Segment %d behind mux can't share classes with ancestors\n",
149 chan_id);
150 else
151 priv->adap.class = class;
152
153 /*
154 * Try to populate the mux adapter's of_node, expands to
155 * nothing if !CONFIG_OF.
156 */
157 if (mux_dev->of_node) {
158 struct device_node *child;
159 u32 reg;
160
161 for_each_child_of_node(mux_dev->of_node, child) {
162 ret = of_property_read_u32(child, "reg", ®);
163 if (ret)
164 continue;
165 if (chan_id == reg) {
166 priv->adap.dev.of_node = child;
167 break;
168 }
169 }
170 }
171
172 if (force_nr) {
173 priv->adap.nr = force_nr;
174 ret = i2c_add_numbered_adapter(&priv->adap);
175 } else {
176 ret = i2c_add_adapter(&priv->adap);
177 }
178 if (ret < 0) {
179 dev_err(&parent->dev,
180 "failed to add mux-adapter (error=%d)\n",
181 ret);
182 kfree(priv);
183 return NULL;
184 }
185
186 dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
187 i2c_adapter_id(&priv->adap));
188
189 return &priv->adap;
190}
191EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
192
193void i2c_del_mux_adapter(struct i2c_adapter *adap)
194{
195 struct i2c_mux_priv *priv = adap->algo_data;
196
197 i2c_del_adapter(adap);
198 kfree(priv);
199}
200EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
201
202MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
203MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
204MODULE_LICENSE("GPL v2");