| 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 | size_t mux_size; |
| 247 | |
| 248 | mux_size = struct_size(muxc, adapter, max_adapters); |
| 249 | muxc = devm_kzalloc(dev, size_add(mux_size, 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(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(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; |
| 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) |
| 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(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; |
| 387 | } |
| 388 | } |
| 389 | |
| 390 | priv->adap.dev.of_node = child; |
| 391 | of_node_put(mux_node); |
| 392 | } |
| 393 | |
| 394 | /* |
| 395 | * Associate the mux channel with an ACPI node. |
| 396 | */ |
| 397 | if (has_acpi_companion(muxc->dev)) |
| 398 | acpi_preset_companion(&priv->adap.dev, |
| 399 | ACPI_COMPANION(muxc->dev), |
| 400 | chan_id); |
| 401 | |
| 402 | if (force_nr) { |
| 403 | priv->adap.nr = force_nr; |
| 404 | ret = i2c_add_numbered_adapter(&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(&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(symlink_name, sizeof(symlink_name), "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(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(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); |
| 458 | of_node_put(np); |
| 459 | kfree(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"); |