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(adap: 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(adap: 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(adapter: parent, addr, flags, |
92 | read_write, command, protocol: 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(adapter: parent, addr, flags, |
114 | read_write, command, protocol: 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(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(lock: &parent->mux_lock, subclass: i2c_adapter_depth(adapter)); |
149 | if (!(flags & I2C_LOCK_ROOT_ADAPTER)) |
150 | return; |
151 | i2c_lock_bus(adapter: 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(lock: &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(adapter: parent, flags)) |
164 | return 1; /* parent locked too, success */ |
165 | rt_mutex_unlock(lock: &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(adapter: parent, flags); |
176 | rt_mutex_unlock(lock: &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(lock: &parent->mux_lock, subclass: i2c_adapter_depth(adapter)); |
186 | i2c_lock_bus(adapter: 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(lock: &parent->mux_lock)) |
196 | return 0; /* mux_lock not locked, failure */ |
197 | if (i2c_trylock_bus(adapter: parent, flags)) |
198 | return 1; /* parent locked too, success */ |
199 | rt_mutex_unlock(lock: &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(adapter: parent, flags); |
210 | rt_mutex_unlock(lock: &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(adapter: i2c_root)) |
233 | i2c_root = i2c_parent_is_i2c_adapter(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 | size_t mux_size; |
247 | |
248 | mux_size = struct_size(muxc, adapter, max_adapters); |
249 | muxc = devm_kzalloc(dev, size: size_add(addend1: mux_size, addend2: sizeof_priv), GFP_KERNEL); |
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; |
257 | if (flags & I2C_MUX_LOCKED) |
258 | muxc->mux_locked = true; |
259 | if (flags & I2C_MUX_ARBITRATOR) |
260 | muxc->arbitrator = true; |
261 | if (flags & I2C_MUX_GATE) |
262 | muxc->gate = true; |
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 | |
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 | |
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; |
288 | struct i2c_mux_priv *priv; |
289 | char symlink_name[20]; |
290 | int ret; |
291 | |
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(size: sizeof(*priv), GFP_KERNEL); |
298 | if (!priv) |
299 | return -ENOMEM; |
300 | |
301 | /* Set up private adapter data */ |
302 | priv->muxc = muxc; |
303 | priv->chan_id = chan_id; |
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 | */ |
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 | } |
314 | if (parent->algo->master_xfer_atomic) |
315 | priv->algo.master_xfer_atomic = priv->algo.master_xfer; |
316 | |
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 | } |
323 | if (parent->algo->smbus_xfer_atomic) |
324 | priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer; |
325 | |
326 | priv->algo.functionality = i2c_mux_functionality; |
327 | |
328 | /* Now fill out new adapter structure */ |
329 | snprintf(buf: priv->adap.name, size: sizeof(priv->adap.name), |
330 | fmt: "i2c-%d-mux (chan_id %d)" , i2c_adapter_id(adap: parent), chan_id); |
331 | priv->adap.owner = THIS_MODULE; |
332 | priv->adap.algo = &priv->algo; |
333 | priv->adap.algo_data = priv; |
334 | priv->adap.dev.parent = &parent->dev; |
335 | priv->adap.retries = parent->retries; |
336 | priv->adap.timeout = parent->timeout; |
337 | priv->adap.quirks = parent->quirks; |
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; |
342 | |
343 | /* Sanity check on class */ |
344 | if (i2c_mux_parent_classes(parent) & class & ~I2C_CLASS_DEPRECATED) |
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 | |
351 | /* |
352 | * Try to populate the mux adapter's of_node, expands to |
353 | * nothing if !CONFIG_OF. |
354 | */ |
355 | if (muxc->dev->of_node) { |
356 | struct device_node *dev_node = muxc->dev->of_node; |
357 | struct device_node *mux_node, *child = NULL; |
358 | u32 reg; |
359 | |
360 | if (muxc->arbitrator) |
361 | mux_node = of_get_child_by_name(node: dev_node, name: "i2c-arb" ); |
362 | else if (muxc->gate) |
363 | mux_node = of_get_child_by_name(node: dev_node, name: "i2c-gate" ); |
364 | else |
365 | mux_node = of_get_child_by_name(node: dev_node, name: "i2c-mux" ); |
366 | |
367 | if (mux_node) { |
368 | /* A "reg" property indicates an old-style DT entry */ |
369 | if (!of_property_read_u32(np: mux_node, propname: "reg" , out_value: ®)) { |
370 | of_node_put(node: mux_node); |
371 | mux_node = NULL; |
372 | } |
373 | } |
374 | |
375 | if (!mux_node) |
376 | mux_node = of_node_get(node: dev_node); |
377 | else if (muxc->arbitrator || muxc->gate) |
378 | child = of_node_get(node: mux_node); |
379 | |
380 | if (!child) { |
381 | for_each_child_of_node(mux_node, child) { |
382 | ret = of_property_read_u32(np: child, propname: "reg" , out_value: ®); |
383 | if (ret) |
384 | continue; |
385 | if (chan_id == reg) |
386 | break; |
387 | } |
388 | } |
389 | |
390 | priv->adap.dev.of_node = child; |
391 | of_node_put(node: mux_node); |
392 | } |
393 | |
394 | /* |
395 | * Associate the mux channel with an ACPI node. |
396 | */ |
397 | if (has_acpi_companion(dev: muxc->dev)) |
398 | acpi_preset_companion(dev: &priv->adap.dev, |
399 | ACPI_COMPANION(muxc->dev), |
400 | addr: chan_id); |
401 | |
402 | if (force_nr) { |
403 | priv->adap.nr = force_nr; |
404 | ret = i2c_add_numbered_adapter(adap: &priv->adap); |
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 | } |
411 | } else { |
412 | ret = i2c_add_adapter(adap: &priv->adap); |
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 | } |
419 | } |
420 | |
421 | WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj, |
422 | "mux_device" ), |
423 | "can't create symlink to mux device\n" ); |
424 | |
425 | snprintf(buf: symlink_name, size: sizeof(symlink_name), fmt: "channel-%u" , chan_id); |
426 | WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj, |
427 | symlink_name), |
428 | "can't create symlink to channel %u\n" , chan_id); |
429 | dev_info(&parent->dev, "Added multiplexed i2c bus %d\n" , |
430 | i2c_adapter_id(&priv->adap)); |
431 | |
432 | muxc->adapter[muxc->num_adapters++] = &priv->adap; |
433 | return 0; |
434 | |
435 | err_free_priv: |
436 | kfree(objp: priv); |
437 | return ret; |
438 | } |
439 | EXPORT_SYMBOL_GPL(i2c_mux_add_adapter); |
440 | |
441 | void i2c_mux_del_adapters(struct i2c_mux_core *muxc) |
442 | { |
443 | char symlink_name[20]; |
444 | |
445 | while (muxc->num_adapters) { |
446 | struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters]; |
447 | struct i2c_mux_priv *priv = adap->algo_data; |
448 | struct device_node *np = adap->dev.of_node; |
449 | |
450 | muxc->adapter[muxc->num_adapters] = NULL; |
451 | |
452 | snprintf(buf: symlink_name, size: sizeof(symlink_name), |
453 | fmt: "channel-%u" , priv->chan_id); |
454 | sysfs_remove_link(kobj: &muxc->dev->kobj, name: symlink_name); |
455 | |
456 | sysfs_remove_link(kobj: &priv->adap.dev.kobj, name: "mux_device" ); |
457 | i2c_del_adapter(adap); |
458 | of_node_put(node: np); |
459 | kfree(objp: priv); |
460 | } |
461 | } |
462 | EXPORT_SYMBOL_GPL(i2c_mux_del_adapters); |
463 | |
464 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>" ); |
465 | MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses" ); |
466 | MODULE_LICENSE("GPL v2" ); |
467 | |