Merge branch 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
[linux-2.6-microblaze.git] / drivers / i2c / i2c-mux.c
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 #include <linux/sysfs.h>
30
31 /* multiplexer per channel data */
32 struct i2c_mux_priv {
33         struct i2c_adapter adap;
34         struct i2c_algorithm algo;
35         struct i2c_mux_core *muxc;
36         u32 chan_id;
37 };
38
39 static int __i2c_mux_master_xfer(struct i2c_adapter *adap,
40                                  struct i2c_msg msgs[], int num)
41 {
42         struct i2c_mux_priv *priv = adap->algo_data;
43         struct i2c_mux_core *muxc = priv->muxc;
44         struct i2c_adapter *parent = muxc->parent;
45         int ret;
46
47         /* Switch to the right mux port and perform the transfer. */
48
49         ret = muxc->select(muxc, priv->chan_id);
50         if (ret >= 0)
51                 ret = __i2c_transfer(parent, msgs, num);
52         if (muxc->deselect)
53                 muxc->deselect(muxc, priv->chan_id);
54
55         return ret;
56 }
57
58 static int i2c_mux_master_xfer(struct i2c_adapter *adap,
59                                struct i2c_msg msgs[], int num)
60 {
61         struct i2c_mux_priv *priv = adap->algo_data;
62         struct i2c_mux_core *muxc = priv->muxc;
63         struct i2c_adapter *parent = muxc->parent;
64         int ret;
65
66         /* Switch to the right mux port and perform the transfer. */
67
68         ret = muxc->select(muxc, priv->chan_id);
69         if (ret >= 0)
70                 ret = i2c_transfer(parent, msgs, num);
71         if (muxc->deselect)
72                 muxc->deselect(muxc, priv->chan_id);
73
74         return ret;
75 }
76
77 static int __i2c_mux_smbus_xfer(struct i2c_adapter *adap,
78                                 u16 addr, unsigned short flags,
79                                 char read_write, u8 command,
80                                 int size, union i2c_smbus_data *data)
81 {
82         struct i2c_mux_priv *priv = adap->algo_data;
83         struct i2c_mux_core *muxc = priv->muxc;
84         struct i2c_adapter *parent = muxc->parent;
85         int ret;
86
87         /* Select the right mux port and perform the transfer. */
88
89         ret = muxc->select(muxc, priv->chan_id);
90         if (ret >= 0)
91                 ret = __i2c_smbus_xfer(parent, addr, flags,
92                                        read_write, command, size, data);
93         if (muxc->deselect)
94                 muxc->deselect(muxc, priv->chan_id);
95
96         return ret;
97 }
98
99 static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
100                               u16 addr, unsigned short flags,
101                               char read_write, u8 command,
102                               int size, union i2c_smbus_data *data)
103 {
104         struct i2c_mux_priv *priv = adap->algo_data;
105         struct i2c_mux_core *muxc = priv->muxc;
106         struct i2c_adapter *parent = muxc->parent;
107         int ret;
108
109         /* Select the right mux port and perform the transfer. */
110
111         ret = muxc->select(muxc, priv->chan_id);
112         if (ret >= 0)
113                 ret = i2c_smbus_xfer(parent, addr, flags,
114                                      read_write, command, size, data);
115         if (muxc->deselect)
116                 muxc->deselect(muxc, priv->chan_id);
117
118         return ret;
119 }
120
121 /* Return the parent's functionality */
122 static u32 i2c_mux_functionality(struct i2c_adapter *adap)
123 {
124         struct i2c_mux_priv *priv = adap->algo_data;
125         struct i2c_adapter *parent = priv->muxc->parent;
126
127         return parent->algo->functionality(parent);
128 }
129
130 /* Return all parent classes, merged */
131 static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
132 {
133         unsigned int class = 0;
134
135         do {
136                 class |= parent->class;
137                 parent = i2c_parent_is_i2c_adapter(parent);
138         } while (parent);
139
140         return class;
141 }
142
143 static void i2c_mux_lock_bus(struct i2c_adapter *adapter, unsigned int flags)
144 {
145         struct i2c_mux_priv *priv = adapter->algo_data;
146         struct i2c_adapter *parent = priv->muxc->parent;
147
148         rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));
149         if (!(flags & I2C_LOCK_ROOT_ADAPTER))
150                 return;
151         i2c_lock_bus(parent, flags);
152 }
153
154 static int i2c_mux_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)
155 {
156         struct i2c_mux_priv *priv = adapter->algo_data;
157         struct i2c_adapter *parent = priv->muxc->parent;
158
159         if (!rt_mutex_trylock(&parent->mux_lock))
160                 return 0;       /* mux_lock not locked, failure */
161         if (!(flags & I2C_LOCK_ROOT_ADAPTER))
162                 return 1;       /* we only want mux_lock, success */
163         if (i2c_trylock_bus(parent, flags))
164                 return 1;       /* parent locked too, success */
165         rt_mutex_unlock(&parent->mux_lock);
166         return 0;               /* parent not locked, failure */
167 }
168
169 static void i2c_mux_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)
170 {
171         struct i2c_mux_priv *priv = adapter->algo_data;
172         struct i2c_adapter *parent = priv->muxc->parent;
173
174         if (flags & I2C_LOCK_ROOT_ADAPTER)
175                 i2c_unlock_bus(parent, flags);
176         rt_mutex_unlock(&parent->mux_lock);
177 }
178
179 static void i2c_parent_lock_bus(struct i2c_adapter *adapter,
180                                 unsigned int flags)
181 {
182         struct i2c_mux_priv *priv = adapter->algo_data;
183         struct i2c_adapter *parent = priv->muxc->parent;
184
185         rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));
186         i2c_lock_bus(parent, flags);
187 }
188
189 static int i2c_parent_trylock_bus(struct i2c_adapter *adapter,
190                                   unsigned int flags)
191 {
192         struct i2c_mux_priv *priv = adapter->algo_data;
193         struct i2c_adapter *parent = priv->muxc->parent;
194
195         if (!rt_mutex_trylock(&parent->mux_lock))
196                 return 0;       /* mux_lock not locked, failure */
197         if (i2c_trylock_bus(parent, flags))
198                 return 1;       /* parent locked too, success */
199         rt_mutex_unlock(&parent->mux_lock);
200         return 0;               /* parent not locked, failure */
201 }
202
203 static void i2c_parent_unlock_bus(struct i2c_adapter *adapter,
204                                   unsigned int flags)
205 {
206         struct i2c_mux_priv *priv = adapter->algo_data;
207         struct i2c_adapter *parent = priv->muxc->parent;
208
209         i2c_unlock_bus(parent, flags);
210         rt_mutex_unlock(&parent->mux_lock);
211 }
212
213 struct i2c_adapter *i2c_root_adapter(struct device *dev)
214 {
215         struct device *i2c;
216         struct i2c_adapter *i2c_root;
217
218         /*
219          * Walk up the device tree to find an i2c adapter, indicating
220          * that this is an i2c client device. Check all ancestors to
221          * handle mfd devices etc.
222          */
223         for (i2c = dev; i2c; i2c = i2c->parent) {
224                 if (i2c->type == &i2c_adapter_type)
225                         break;
226         }
227         if (!i2c)
228                 return NULL;
229
230         /* Continue up the tree to find the root i2c adapter */
231         i2c_root = to_i2c_adapter(i2c);
232         while (i2c_parent_is_i2c_adapter(i2c_root))
233                 i2c_root = i2c_parent_is_i2c_adapter(i2c_root);
234
235         return i2c_root;
236 }
237 EXPORT_SYMBOL_GPL(i2c_root_adapter);
238
239 struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
240                                    struct device *dev, int max_adapters,
241                                    int sizeof_priv, u32 flags,
242                                    int (*select)(struct i2c_mux_core *, u32),
243                                    int (*deselect)(struct i2c_mux_core *, u32))
244 {
245         struct i2c_mux_core *muxc;
246
247         muxc = devm_kzalloc(dev, struct_size(muxc, adapter, max_adapters)
248                             + sizeof_priv, GFP_KERNEL);
249         if (!muxc)
250                 return NULL;
251         if (sizeof_priv)
252                 muxc->priv = &muxc->adapter[max_adapters];
253
254         muxc->parent = parent;
255         muxc->dev = dev;
256         if (flags & I2C_MUX_LOCKED)
257                 muxc->mux_locked = true;
258         if (flags & I2C_MUX_ARBITRATOR)
259                 muxc->arbitrator = true;
260         if (flags & I2C_MUX_GATE)
261                 muxc->gate = true;
262         muxc->select = select;
263         muxc->deselect = deselect;
264         muxc->max_adapters = max_adapters;
265
266         return muxc;
267 }
268 EXPORT_SYMBOL_GPL(i2c_mux_alloc);
269
270 static const struct i2c_lock_operations i2c_mux_lock_ops = {
271         .lock_bus =    i2c_mux_lock_bus,
272         .trylock_bus = i2c_mux_trylock_bus,
273         .unlock_bus =  i2c_mux_unlock_bus,
274 };
275
276 static const struct i2c_lock_operations i2c_parent_lock_ops = {
277         .lock_bus =    i2c_parent_lock_bus,
278         .trylock_bus = i2c_parent_trylock_bus,
279         .unlock_bus =  i2c_parent_unlock_bus,
280 };
281
282 int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
283                         u32 force_nr, u32 chan_id,
284                         unsigned int class)
285 {
286         struct i2c_adapter *parent = muxc->parent;
287         struct i2c_mux_priv *priv;
288         char symlink_name[20];
289         int ret;
290
291         if (muxc->num_adapters >= muxc->max_adapters) {
292                 dev_err(muxc->dev, "No room for more i2c-mux adapters\n");
293                 return -EINVAL;
294         }
295
296         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
297         if (!priv)
298                 return -ENOMEM;
299
300         /* Set up private adapter data */
301         priv->muxc = muxc;
302         priv->chan_id = chan_id;
303
304         /* Need to do algo dynamically because we don't know ahead
305          * of time what sort of physical adapter we'll be dealing with.
306          */
307         if (parent->algo->master_xfer) {
308                 if (muxc->mux_locked)
309                         priv->algo.master_xfer = i2c_mux_master_xfer;
310                 else
311                         priv->algo.master_xfer = __i2c_mux_master_xfer;
312         }
313         if (parent->algo->master_xfer_atomic)
314                 priv->algo.master_xfer_atomic = priv->algo.master_xfer;
315
316         if (parent->algo->smbus_xfer) {
317                 if (muxc->mux_locked)
318                         priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
319                 else
320                         priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;
321         }
322         if (parent->algo->smbus_xfer_atomic)
323                 priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer;
324
325         priv->algo.functionality = i2c_mux_functionality;
326
327         /* Now fill out new adapter structure */
328         snprintf(priv->adap.name, sizeof(priv->adap.name),
329                  "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
330         priv->adap.owner = THIS_MODULE;
331         priv->adap.algo = &priv->algo;
332         priv->adap.algo_data = priv;
333         priv->adap.dev.parent = &parent->dev;
334         priv->adap.retries = parent->retries;
335         priv->adap.timeout = parent->timeout;
336         priv->adap.quirks = parent->quirks;
337         if (muxc->mux_locked)
338                 priv->adap.lock_ops = &i2c_mux_lock_ops;
339         else
340                 priv->adap.lock_ops = &i2c_parent_lock_ops;
341
342         /* Sanity check on class */
343         if (i2c_mux_parent_classes(parent) & class)
344                 dev_err(&parent->dev,
345                         "Segment %d behind mux can't share classes with ancestors\n",
346                         chan_id);
347         else
348                 priv->adap.class = class;
349
350         /*
351          * Try to populate the mux adapter's of_node, expands to
352          * nothing if !CONFIG_OF.
353          */
354         if (muxc->dev->of_node) {
355                 struct device_node *dev_node = muxc->dev->of_node;
356                 struct device_node *mux_node, *child = NULL;
357                 u32 reg;
358
359                 if (muxc->arbitrator)
360                         mux_node = of_get_child_by_name(dev_node, "i2c-arb");
361                 else if (muxc->gate)
362                         mux_node = of_get_child_by_name(dev_node, "i2c-gate");
363                 else
364                         mux_node = of_get_child_by_name(dev_node, "i2c-mux");
365
366                 if (mux_node) {
367                         /* A "reg" property indicates an old-style DT entry */
368                         if (!of_property_read_u32(mux_node, "reg", &reg)) {
369                                 of_node_put(mux_node);
370                                 mux_node = NULL;
371                         }
372                 }
373
374                 if (!mux_node)
375                         mux_node = of_node_get(dev_node);
376                 else if (muxc->arbitrator || muxc->gate)
377                         child = of_node_get(mux_node);
378
379                 if (!child) {
380                         for_each_child_of_node(mux_node, child) {
381                                 ret = of_property_read_u32(child, "reg", &reg);
382                                 if (ret)
383                                         continue;
384                                 if (chan_id == reg)
385                                         break;
386                         }
387                 }
388
389                 priv->adap.dev.of_node = child;
390                 of_node_put(mux_node);
391         }
392
393         /*
394          * Associate the mux channel with an ACPI node.
395          */
396         if (has_acpi_companion(muxc->dev))
397                 acpi_preset_companion(&priv->adap.dev,
398                                       ACPI_COMPANION(muxc->dev),
399                                       chan_id);
400
401         if (force_nr) {
402                 priv->adap.nr = force_nr;
403                 ret = i2c_add_numbered_adapter(&priv->adap);
404                 if (ret < 0) {
405                         dev_err(&parent->dev,
406                                 "failed to add mux-adapter %u as bus %u (error=%d)\n",
407                                 chan_id, force_nr, ret);
408                         goto err_free_priv;
409                 }
410         } else {
411                 ret = i2c_add_adapter(&priv->adap);
412                 if (ret < 0) {
413                         dev_err(&parent->dev,
414                                 "failed to add mux-adapter %u (error=%d)\n",
415                                 chan_id, ret);
416                         goto err_free_priv;
417                 }
418         }
419
420         WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj,
421                                "mux_device"),
422              "can't create symlink to mux device\n");
423
424         snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
425         WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj,
426                                symlink_name),
427              "can't create symlink to channel %u\n", chan_id);
428         dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
429                  i2c_adapter_id(&priv->adap));
430
431         muxc->adapter[muxc->num_adapters++] = &priv->adap;
432         return 0;
433
434 err_free_priv:
435         kfree(priv);
436         return ret;
437 }
438 EXPORT_SYMBOL_GPL(i2c_mux_add_adapter);
439
440 void i2c_mux_del_adapters(struct i2c_mux_core *muxc)
441 {
442         char symlink_name[20];
443
444         while (muxc->num_adapters) {
445                 struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters];
446                 struct i2c_mux_priv *priv = adap->algo_data;
447                 struct device_node *np = adap->dev.of_node;
448
449                 muxc->adapter[muxc->num_adapters] = NULL;
450
451                 snprintf(symlink_name, sizeof(symlink_name),
452                          "channel-%u", priv->chan_id);
453                 sysfs_remove_link(&muxc->dev->kobj, symlink_name);
454
455                 sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
456                 i2c_del_adapter(adap);
457                 of_node_put(np);
458                 kfree(priv);
459         }
460 }
461 EXPORT_SYMBOL_GPL(i2c_mux_del_adapters);
462
463 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
464 MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
465 MODULE_LICENSE("GPL v2");