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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#include <linux/of_i2c.h>
29
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;
36 void *mux_priv; /* the mux chip/device */
37 u32 chan_id; /* the channel id */
38
39 int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
40 int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
41};
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
52 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
53 if (ret >= 0)
54 ret = parent->algo->master_xfer(parent, msgs, num);
55 if (priv->deselect)
56 priv->deselect(parent, priv->mux_priv, priv->chan_id);
57
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
72 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
73 if (ret >= 0)
74 ret = parent->algo->smbus_xfer(parent, addr, flags,
75 read_write, command, size, data);
76 if (priv->deselect)
77 priv->deselect(parent, priv->mux_priv, priv->chan_id);
78
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
91struct 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 *,
95 void *, u32),
96 int (*deselect) (struct i2c_adapter *,
97 void *, u32))
98{
99 struct i2c_mux_priv *priv;
100 int ret;
101
102 priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
103 if (!priv)
104 return NULL;
105
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;
112
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.
115 */
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;
121
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;
129
130 /*
131 * Try to populate the mux adapter's of_node, expands to
132 * nothing if !CONFIG_OF.
133 */
134 if (mux_dev->of_node) {
135 struct device_node *child;
136 u32 reg;
137
138 for_each_child_of_node(mux_dev->of_node, child) {
139 ret = of_property_read_u32(child, "reg", ®);
140 if (ret)
141 continue;
142 if (chan_id == reg) {
143 priv->adap.dev.of_node = child;
144 break;
145 }
146 }
147 }
148
149 if (force_nr) {
150 priv->adap.nr = force_nr;
151 ret = i2c_add_numbered_adapter(&priv->adap);
152 } else {
153 ret = i2c_add_adapter(&priv->adap);
154 }
155 if (ret < 0) {
156 dev_err(&parent->dev,
157 "failed to add mux-adapter (error=%d)\n",
158 ret);
159 kfree(priv);
160 return NULL;
161 }
162
163 dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
164 i2c_adapter_id(&priv->adap));
165
166 of_i2c_register_devices(&priv->adap);
167
168 return &priv->adap;
169}
170EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
171
172int i2c_del_mux_adapter(struct i2c_adapter *adap)
173{
174 struct i2c_mux_priv *priv = adap->algo_data;
175 int ret;
176
177 ret = i2c_del_adapter(adap);
178 if (ret < 0)
179 return ret;
180 kfree(priv);
181
182 return 0;
183}
184EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
185
186MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
187MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
188MODULE_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");