Commit | Line | Data |
---|---|---|
0826374b ML |
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 | ||
51714932 | 22 | #include <linux/acpi.h> |
0826374b ML |
23 | #include <linux/i2c.h> |
24 | #include <linux/i2c-mux.h> | |
51714932 WS |
25 | #include <linux/kernel.h> |
26 | #include <linux/module.h> | |
bc45449b | 27 | #include <linux/of.h> |
51714932 | 28 | #include <linux/slab.h> |
cfafa80b | 29 | #include <linux/sysfs.h> |
0826374b ML |
30 | |
31 | /* multiplexer per channel data */ | |
32 | struct i2c_mux_priv { | |
33 | struct i2c_adapter adap; | |
34 | struct i2c_algorithm algo; | |
a7ab7239 | 35 | struct i2c_mux_core *muxc; |
13377848 | 36 | u32 chan_id; |
0826374b ML |
37 | }; |
38 | ||
6ef91fcc PR |
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 | ||
0826374b ML |
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; | |
a7ab7239 PR |
62 | struct i2c_mux_core *muxc = priv->muxc; |
63 | struct i2c_adapter *parent = muxc->parent; | |
0826374b ML |
64 | int ret; |
65 | ||
66 | /* Switch to the right mux port and perform the transfer. */ | |
67 | ||
a7ab7239 | 68 | ret = muxc->select(muxc, priv->chan_id); |
0826374b | 69 | if (ret >= 0) |
6ef91fcc PR |
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) | |
25184082 PR |
91 | ret = __i2c_smbus_xfer(parent, addr, flags, |
92 | read_write, command, size, data); | |
a7ab7239 PR |
93 | if (muxc->deselect) |
94 | muxc->deselect(muxc, priv->chan_id); | |
0826374b ML |
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; | |
a7ab7239 PR |
105 | struct i2c_mux_core *muxc = priv->muxc; |
106 | struct i2c_adapter *parent = muxc->parent; | |
0826374b ML |
107 | int ret; |
108 | ||
109 | /* Select the right mux port and perform the transfer. */ | |
110 | ||
a7ab7239 | 111 | ret = muxc->select(muxc, priv->chan_id); |
0826374b | 112 | if (ret >= 0) |
6ef91fcc PR |
113 | ret = i2c_smbus_xfer(parent, addr, flags, |
114 | read_write, command, size, data); | |
a7ab7239 PR |
115 | if (muxc->deselect) |
116 | muxc->deselect(muxc, priv->chan_id); | |
0826374b ML |
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; | |
a7ab7239 | 125 | struct i2c_adapter *parent = priv->muxc->parent; |
0826374b ML |
126 | |
127 | return parent->algo->functionality(parent); | |
128 | } | |
129 | ||
eee543e8 JD |
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 | ||
6ef91fcc PR |
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 | ||
7b94ea50 | 148 | rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter)); |
6ef91fcc PR |
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 */ | |
fb79e09a | 163 | if (i2c_trylock_bus(parent, flags)) |
6ef91fcc PR |
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 | ||
fa96f0cb PR |
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 | ||
7b94ea50 | 185 | rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter)); |
6ef91fcc | 186 | i2c_lock_bus(parent, flags); |
fa96f0cb PR |
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 | ||
6ef91fcc PR |
195 | if (!rt_mutex_trylock(&parent->mux_lock)) |
196 | return 0; /* mux_lock not locked, failure */ | |
fb79e09a | 197 | if (i2c_trylock_bus(parent, flags)) |
6ef91fcc PR |
198 | return 1; /* parent locked too, success */ |
199 | rt_mutex_unlock(&parent->mux_lock); | |
200 | return 0; /* parent not locked, failure */ | |
fa96f0cb PR |
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 | ||
6ef91fcc PR |
209 | i2c_unlock_bus(parent, flags); |
210 | rt_mutex_unlock(&parent->mux_lock); | |
fa96f0cb PR |
211 | } |
212 | ||
6ef91fcc PR |
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 | ||
a7ab7239 PR |
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; | |
b7af938f | 246 | size_t mux_size; |
a7ab7239 | 247 | |
b7af938f DC |
248 | mux_size = struct_size(muxc, adapter, max_adapters); |
249 | muxc = devm_kzalloc(dev, size_add(mux_size, sizeof_priv), GFP_KERNEL); | |
a7ab7239 PR |
250 | if (!muxc) |
251 | return NULL; | |
252 | if (sizeof_priv) | |
253 | muxc->priv = &muxc->adapter[max_adapters]; | |
254 | ||
255 | muxc->parent = parent; | |
256 | muxc->dev = dev; | |
6ef91fcc PR |
257 | if (flags & I2C_MUX_LOCKED) |
258 | muxc->mux_locked = true; | |
b2d57b56 PR |
259 | if (flags & I2C_MUX_ARBITRATOR) |
260 | muxc->arbitrator = true; | |
261 | if (flags & I2C_MUX_GATE) | |
262 | muxc->gate = true; | |
a7ab7239 PR |
263 | muxc->select = select; |
264 | muxc->deselect = deselect; | |
265 | muxc->max_adapters = max_adapters; | |
266 | ||
267 | return muxc; | |
268 | } | |
269 | EXPORT_SYMBOL_GPL(i2c_mux_alloc); | |
270 | ||
d1ed7985 PR |
271 | static const struct i2c_lock_operations i2c_mux_lock_ops = { |
272 | .lock_bus = i2c_mux_lock_bus, | |
273 | .trylock_bus = i2c_mux_trylock_bus, | |
274 | .unlock_bus = i2c_mux_unlock_bus, | |
275 | }; | |
276 | ||
277 | static const struct i2c_lock_operations i2c_parent_lock_ops = { | |
278 | .lock_bus = i2c_parent_lock_bus, | |
279 | .trylock_bus = i2c_parent_trylock_bus, | |
280 | .unlock_bus = i2c_parent_unlock_bus, | |
281 | }; | |
282 | ||
a7ab7239 PR |
283 | int i2c_mux_add_adapter(struct i2c_mux_core *muxc, |
284 | u32 force_nr, u32 chan_id, | |
285 | unsigned int class) | |
286 | { | |
287 | struct i2c_adapter *parent = muxc->parent; | |
0826374b | 288 | struct i2c_mux_priv *priv; |
c9449aff | 289 | char symlink_name[20]; |
0826374b ML |
290 | int ret; |
291 | ||
a7ab7239 PR |
292 | if (muxc->num_adapters >= muxc->max_adapters) { |
293 | dev_err(muxc->dev, "No room for more i2c-mux adapters\n"); | |
294 | return -EINVAL; | |
295 | } | |
296 | ||
297 | priv = kzalloc(sizeof(*priv), GFP_KERNEL); | |
0826374b | 298 | if (!priv) |
a7ab7239 | 299 | return -ENOMEM; |
0826374b ML |
300 | |
301 | /* Set up private adapter data */ | |
a7ab7239 | 302 | priv->muxc = muxc; |
0826374b | 303 | priv->chan_id = chan_id; |
0826374b ML |
304 | |
305 | /* Need to do algo dynamically because we don't know ahead | |
306 | * of time what sort of physical adapter we'll be dealing with. | |
307 | */ | |
6ef91fcc PR |
308 | if (parent->algo->master_xfer) { |
309 | if (muxc->mux_locked) | |
310 | priv->algo.master_xfer = i2c_mux_master_xfer; | |
311 | else | |
312 | priv->algo.master_xfer = __i2c_mux_master_xfer; | |
313 | } | |
7168bff2 WS |
314 | if (parent->algo->master_xfer_atomic) |
315 | priv->algo.master_xfer_atomic = priv->algo.master_xfer; | |
316 | ||
6ef91fcc PR |
317 | if (parent->algo->smbus_xfer) { |
318 | if (muxc->mux_locked) | |
319 | priv->algo.smbus_xfer = i2c_mux_smbus_xfer; | |
320 | else | |
321 | priv->algo.smbus_xfer = __i2c_mux_smbus_xfer; | |
322 | } | |
7168bff2 WS |
323 | if (parent->algo->smbus_xfer_atomic) |
324 | priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer; | |
325 | ||
0826374b ML |
326 | priv->algo.functionality = i2c_mux_functionality; |
327 | ||
328 | /* Now fill out new adapter structure */ | |
329 | snprintf(priv->adap.name, sizeof(priv->adap.name), | |
330 | "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id); | |
331 | priv->adap.owner = THIS_MODULE; | |
0826374b ML |
332 | priv->adap.algo = &priv->algo; |
333 | priv->adap.algo_data = priv; | |
334 | priv->adap.dev.parent = &parent->dev; | |
2212a852 EDB |
335 | priv->adap.retries = parent->retries; |
336 | priv->adap.timeout = parent->timeout; | |
dc362d50 | 337 | priv->adap.quirks = parent->quirks; |
d1ed7985 PR |
338 | if (muxc->mux_locked) |
339 | priv->adap.lock_ops = &i2c_mux_lock_ops; | |
340 | else | |
341 | priv->adap.lock_ops = &i2c_parent_lock_ops; | |
0826374b | 342 | |
eee543e8 | 343 | /* Sanity check on class */ |
b13e59e7 | 344 | if (i2c_mux_parent_classes(parent) & class & ~I2C_CLASS_DEPRECATED) |
eee543e8 JD |
345 | dev_err(&parent->dev, |
346 | "Segment %d behind mux can't share classes with ancestors\n", | |
347 | chan_id); | |
348 | else | |
349 | priv->adap.class = class; | |
350 | ||
bc45449b DD |
351 | /* |
352 | * Try to populate the mux adapter's of_node, expands to | |
353 | * nothing if !CONFIG_OF. | |
354 | */ | |
a7ab7239 | 355 | if (muxc->dev->of_node) { |
b2d57b56 PR |
356 | struct device_node *dev_node = muxc->dev->of_node; |
357 | struct device_node *mux_node, *child = NULL; | |
bc45449b DD |
358 | u32 reg; |
359 | ||
b2d57b56 PR |
360 | if (muxc->arbitrator) |
361 | mux_node = of_get_child_by_name(dev_node, "i2c-arb"); | |
362 | else if (muxc->gate) | |
363 | mux_node = of_get_child_by_name(dev_node, "i2c-gate"); | |
364 | else | |
365 | mux_node = of_get_child_by_name(dev_node, "i2c-mux"); | |
366 | ||
367 | if (mux_node) { | |
368 | /* A "reg" property indicates an old-style DT entry */ | |
369 | if (!of_property_read_u32(mux_node, "reg", ®)) { | |
370 | of_node_put(mux_node); | |
371 | mux_node = NULL; | |
372 | } | |
373 | } | |
374 | ||
375 | if (!mux_node) | |
376 | mux_node = of_node_get(dev_node); | |
377 | else if (muxc->arbitrator || muxc->gate) | |
378 | child = of_node_get(mux_node); | |
379 | ||
380 | if (!child) { | |
381 | for_each_child_of_node(mux_node, child) { | |
382 | ret = of_property_read_u32(child, "reg", ®); | |
383 | if (ret) | |
384 | continue; | |
385 | if (chan_id == reg) | |
386 | break; | |
bc45449b DD |
387 | } |
388 | } | |
b2d57b56 PR |
389 | |
390 | priv->adap.dev.of_node = child; | |
391 | of_node_put(mux_node); | |
bc45449b DD |
392 | } |
393 | ||
8eb5c87a DB |
394 | /* |
395 | * Associate the mux channel with an ACPI node. | |
396 | */ | |
a7ab7239 PR |
397 | if (has_acpi_companion(muxc->dev)) |
398 | acpi_preset_companion(&priv->adap.dev, | |
399 | ACPI_COMPANION(muxc->dev), | |
8eb5c87a DB |
400 | chan_id); |
401 | ||
0826374b ML |
402 | if (force_nr) { |
403 | priv->adap.nr = force_nr; | |
404 | ret = i2c_add_numbered_adapter(&priv->adap); | |
9fce894d PR |
405 | if (ret < 0) { |
406 | dev_err(&parent->dev, | |
407 | "failed to add mux-adapter %u as bus %u (error=%d)\n", | |
408 | chan_id, force_nr, ret); | |
409 | goto err_free_priv; | |
410 | } | |
0826374b ML |
411 | } else { |
412 | ret = i2c_add_adapter(&priv->adap); | |
9fce894d PR |
413 | if (ret < 0) { |
414 | dev_err(&parent->dev, | |
415 | "failed to add mux-adapter %u (error=%d)\n", | |
416 | chan_id, ret); | |
417 | goto err_free_priv; | |
418 | } | |
0826374b ML |
419 | } |
420 | ||
a7ab7239 PR |
421 | WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj, |
422 | "mux_device"), | |
423 | "can't create symlink to mux device\n"); | |
51cf3b0e | 424 | |
c9449aff | 425 | snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id); |
a7ab7239 PR |
426 | WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj, |
427 | symlink_name), | |
f657c9fe | 428 | "can't create symlink to channel %u\n", chan_id); |
0826374b ML |
429 | dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", |
430 | i2c_adapter_id(&priv->adap)); | |
431 | ||
a7ab7239 PR |
432 | muxc->adapter[muxc->num_adapters++] = &priv->adap; |
433 | return 0; | |
9fce894d PR |
434 | |
435 | err_free_priv: | |
436 | kfree(priv); | |
437 | return ret; | |
0826374b | 438 | } |
a7ab7239 | 439 | EXPORT_SYMBOL_GPL(i2c_mux_add_adapter); |
0826374b | 440 | |
a7ab7239 | 441 | void i2c_mux_del_adapters(struct i2c_mux_core *muxc) |
0826374b | 442 | { |
c9449aff GF |
443 | char symlink_name[20]; |
444 | ||
a7ab7239 PR |
445 | while (muxc->num_adapters) { |
446 | struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters]; | |
447 | struct i2c_mux_priv *priv = adap->algo_data; | |
2e1e4949 | 448 | struct device_node *np = adap->dev.of_node; |
a7ab7239 PR |
449 | |
450 | muxc->adapter[muxc->num_adapters] = NULL; | |
451 | ||
452 | snprintf(symlink_name, sizeof(symlink_name), | |
453 | "channel-%u", priv->chan_id); | |
454 | sysfs_remove_link(&muxc->dev->kobj, symlink_name); | |
455 | ||
456 | sysfs_remove_link(&priv->adap.dev.kobj, "mux_device"); | |
457 | i2c_del_adapter(adap); | |
2e1e4949 | 458 | of_node_put(np); |
a7ab7239 PR |
459 | kfree(priv); |
460 | } | |
461 | } | |
462 | EXPORT_SYMBOL_GPL(i2c_mux_del_adapters); | |
463 | ||
0826374b ML |
464 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); |
465 | MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); | |
466 | MODULE_LICENSE("GPL v2"); |