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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/acpi.h>
23#include <linux/i2c.h>
24#include <linux/i2c-mux.h>
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/of.h>
28#include <linux/slab.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 struct device *mux_dev;
37 void *mux_priv;
38 u32 chan_id;
39
40 int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
41 int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
42};
43
44static int i2c_mux_master_xfer(struct i2c_adapter *adap,
45 struct i2c_msg msgs[], int num)
46{
47 struct i2c_mux_priv *priv = adap->algo_data;
48 struct i2c_adapter *parent = priv->parent;
49 int ret;
50
51 /* Switch to the right mux port and perform the transfer. */
52
53 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
54 if (ret >= 0)
55 ret = __i2c_transfer(parent, msgs, num);
56 if (priv->deselect)
57 priv->deselect(parent, priv->mux_priv, priv->chan_id);
58
59 return ret;
60}
61
62static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
63 u16 addr, unsigned short flags,
64 char read_write, u8 command,
65 int size, union i2c_smbus_data *data)
66{
67 struct i2c_mux_priv *priv = adap->algo_data;
68 struct i2c_adapter *parent = priv->parent;
69 int ret;
70
71 /* Select the right mux port and perform the transfer. */
72
73 ret = priv->select(parent, priv->mux_priv, priv->chan_id);
74 if (ret >= 0)
75 ret = parent->algo->smbus_xfer(parent, addr, flags,
76 read_write, command, size, data);
77 if (priv->deselect)
78 priv->deselect(parent, priv->mux_priv, priv->chan_id);
79
80 return ret;
81}
82
83/* Return the parent's functionality */
84static u32 i2c_mux_functionality(struct i2c_adapter *adap)
85{
86 struct i2c_mux_priv *priv = adap->algo_data;
87 struct i2c_adapter *parent = priv->parent;
88
89 return parent->algo->functionality(parent);
90}
91
92/* Return all parent classes, merged */
93static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
94{
95 unsigned int class = 0;
96
97 do {
98 class |= parent->class;
99 parent = i2c_parent_is_i2c_adapter(parent);
100 } while (parent);
101
102 return class;
103}
104
105struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
106 struct device *mux_dev,
107 void *mux_priv, u32 force_nr, u32 chan_id,
108 unsigned int class,
109 int (*select) (struct i2c_adapter *,
110 void *, u32),
111 int (*deselect) (struct i2c_adapter *,
112 void *, u32))
113{
114 struct i2c_mux_priv *priv;
115 char symlink_name[20];
116 int ret;
117
118 priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
119 if (!priv)
120 return NULL;
121
122 /* Set up private adapter data */
123 priv->parent = parent;
124 priv->mux_dev = mux_dev;
125 priv->mux_priv = mux_priv;
126 priv->chan_id = chan_id;
127 priv->select = select;
128 priv->deselect = deselect;
129
130 /* Need to do algo dynamically because we don't know ahead
131 * of time what sort of physical adapter we'll be dealing with.
132 */
133 if (parent->algo->master_xfer)
134 priv->algo.master_xfer = i2c_mux_master_xfer;
135 if (parent->algo->smbus_xfer)
136 priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
137 priv->algo.functionality = i2c_mux_functionality;
138
139 /* Now fill out new adapter structure */
140 snprintf(priv->adap.name, sizeof(priv->adap.name),
141 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
142 priv->adap.owner = THIS_MODULE;
143 priv->adap.algo = &priv->algo;
144 priv->adap.algo_data = priv;
145 priv->adap.dev.parent = &parent->dev;
146 priv->adap.retries = parent->retries;
147 priv->adap.timeout = parent->timeout;
148 priv->adap.quirks = parent->quirks;
149
150 /* Sanity check on class */
151 if (i2c_mux_parent_classes(parent) & class)
152 dev_err(&parent->dev,
153 "Segment %d behind mux can't share classes with ancestors\n",
154 chan_id);
155 else
156 priv->adap.class = class;
157
158 /*
159 * Try to populate the mux adapter's of_node, expands to
160 * nothing if !CONFIG_OF.
161 */
162 if (mux_dev->of_node) {
163 struct device_node *child;
164 u32 reg;
165
166 for_each_child_of_node(mux_dev->of_node, child) {
167 ret = of_property_read_u32(child, "reg", ®);
168 if (ret)
169 continue;
170 if (chan_id == reg) {
171 priv->adap.dev.of_node = child;
172 break;
173 }
174 }
175 }
176
177 /*
178 * Associate the mux channel with an ACPI node.
179 */
180 if (has_acpi_companion(mux_dev))
181 acpi_preset_companion(&priv->adap.dev, ACPI_COMPANION(mux_dev),
182 chan_id);
183
184 if (force_nr) {
185 priv->adap.nr = force_nr;
186 ret = i2c_add_numbered_adapter(&priv->adap);
187 } else {
188 ret = i2c_add_adapter(&priv->adap);
189 }
190 if (ret < 0) {
191 dev_err(&parent->dev,
192 "failed to add mux-adapter (error=%d)\n",
193 ret);
194 kfree(priv);
195 return NULL;
196 }
197
198 WARN(sysfs_create_link(&priv->adap.dev.kobj, &mux_dev->kobj, "mux_device"),
199 "can't create symlink to mux device\n");
200
201 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
202 WARN(sysfs_create_link(&mux_dev->kobj, &priv->adap.dev.kobj, symlink_name),
203 "can't create symlink for channel %u\n", chan_id);
204 dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
205 i2c_adapter_id(&priv->adap));
206
207 return &priv->adap;
208}
209EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
210
211void i2c_del_mux_adapter(struct i2c_adapter *adap)
212{
213 struct i2c_mux_priv *priv = adap->algo_data;
214 char symlink_name[20];
215
216 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", priv->chan_id);
217 sysfs_remove_link(&priv->mux_dev->kobj, symlink_name);
218
219 sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
220 i2c_del_adapter(adap);
221 kfree(priv);
222}
223EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
224
225MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
226MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
227MODULE_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#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");