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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 presenting9 * 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 Public18 * License version 2. This program is licensed "as is" without any19 * 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 */32struct 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 39static 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 58static 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 77static 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 99static 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 */122static 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 130static void i2c_mux_lock_bus(struct i2c_adapter *adapter, unsigned int flags)131{132 struct i2c_mux_priv *priv = adapter->algo_data;133 struct i2c_adapter *parent = priv->muxc->parent;134 135 rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));136 if (!(flags & I2C_LOCK_ROOT_ADAPTER))137 return;138 i2c_lock_bus(parent, flags);139}140 141static int i2c_mux_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)142{143 struct i2c_mux_priv *priv = adapter->algo_data;144 struct i2c_adapter *parent = priv->muxc->parent;145 146 if (!rt_mutex_trylock(&parent->mux_lock))147 return 0; /* mux_lock not locked, failure */148 if (!(flags & I2C_LOCK_ROOT_ADAPTER))149 return 1; /* we only want mux_lock, success */150 if (i2c_trylock_bus(parent, flags))151 return 1; /* parent locked too, success */152 rt_mutex_unlock(&parent->mux_lock);153 return 0; /* parent not locked, failure */154}155 156static void i2c_mux_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)157{158 struct i2c_mux_priv *priv = adapter->algo_data;159 struct i2c_adapter *parent = priv->muxc->parent;160 161 if (flags & I2C_LOCK_ROOT_ADAPTER)162 i2c_unlock_bus(parent, flags);163 rt_mutex_unlock(&parent->mux_lock);164}165 166static void i2c_parent_lock_bus(struct i2c_adapter *adapter,167 unsigned int flags)168{169 struct i2c_mux_priv *priv = adapter->algo_data;170 struct i2c_adapter *parent = priv->muxc->parent;171 172 rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));173 i2c_lock_bus(parent, flags);174}175 176static int i2c_parent_trylock_bus(struct i2c_adapter *adapter,177 unsigned int flags)178{179 struct i2c_mux_priv *priv = adapter->algo_data;180 struct i2c_adapter *parent = priv->muxc->parent;181 182 if (!rt_mutex_trylock(&parent->mux_lock))183 return 0; /* mux_lock not locked, failure */184 if (i2c_trylock_bus(parent, flags))185 return 1; /* parent locked too, success */186 rt_mutex_unlock(&parent->mux_lock);187 return 0; /* parent not locked, failure */188}189 190static void i2c_parent_unlock_bus(struct i2c_adapter *adapter,191 unsigned int flags)192{193 struct i2c_mux_priv *priv = adapter->algo_data;194 struct i2c_adapter *parent = priv->muxc->parent;195 196 i2c_unlock_bus(parent, flags);197 rt_mutex_unlock(&parent->mux_lock);198}199 200struct i2c_adapter *i2c_root_adapter(struct device *dev)201{202 struct device *i2c;203 struct i2c_adapter *i2c_root;204 205 /*206 * Walk up the device tree to find an i2c adapter, indicating207 * that this is an i2c client device. Check all ancestors to208 * handle mfd devices etc.209 */210 for (i2c = dev; i2c; i2c = i2c->parent) {211 if (i2c->type == &i2c_adapter_type)212 break;213 }214 if (!i2c)215 return NULL;216 217 /* Continue up the tree to find the root i2c adapter */218 i2c_root = to_i2c_adapter(i2c);219 while (i2c_parent_is_i2c_adapter(i2c_root))220 i2c_root = i2c_parent_is_i2c_adapter(i2c_root);221 222 return i2c_root;223}224EXPORT_SYMBOL_GPL(i2c_root_adapter);225 226struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,227 struct device *dev, int max_adapters,228 int sizeof_priv, u32 flags,229 int (*select)(struct i2c_mux_core *, u32),230 int (*deselect)(struct i2c_mux_core *, u32))231{232 struct i2c_mux_core *muxc;233 size_t mux_size;234 235 mux_size = struct_size(muxc, adapter, max_adapters);236 muxc = devm_kzalloc(dev, size_add(mux_size, sizeof_priv), GFP_KERNEL);237 if (!muxc)238 return NULL;239 if (sizeof_priv)240 muxc->priv = &muxc->adapter[max_adapters];241 242 muxc->parent = parent;243 muxc->dev = dev;244 if (flags & I2C_MUX_LOCKED)245 muxc->mux_locked = true;246 if (flags & I2C_MUX_ARBITRATOR)247 muxc->arbitrator = true;248 if (flags & I2C_MUX_GATE)249 muxc->gate = true;250 muxc->select = select;251 muxc->deselect = deselect;252 muxc->max_adapters = max_adapters;253 254 return muxc;255}256EXPORT_SYMBOL_GPL(i2c_mux_alloc);257 258static const struct i2c_lock_operations i2c_mux_lock_ops = {259 .lock_bus = i2c_mux_lock_bus,260 .trylock_bus = i2c_mux_trylock_bus,261 .unlock_bus = i2c_mux_unlock_bus,262};263 264static const struct i2c_lock_operations i2c_parent_lock_ops = {265 .lock_bus = i2c_parent_lock_bus,266 .trylock_bus = i2c_parent_trylock_bus,267 .unlock_bus = i2c_parent_unlock_bus,268};269 270int i2c_mux_add_adapter(struct i2c_mux_core *muxc,271 u32 force_nr, u32 chan_id)272{273 struct i2c_adapter *parent = muxc->parent;274 struct i2c_mux_priv *priv;275 char symlink_name[20];276 int ret;277 278 if (muxc->num_adapters >= muxc->max_adapters) {279 dev_err(muxc->dev, "No room for more i2c-mux adapters\n");280 return -EINVAL;281 }282 283 priv = kzalloc(sizeof(*priv), GFP_KERNEL);284 if (!priv)285 return -ENOMEM;286 287 /* Set up private adapter data */288 priv->muxc = muxc;289 priv->chan_id = chan_id;290 291 /* Need to do algo dynamically because we don't know ahead292 * of time what sort of physical adapter we'll be dealing with.293 */294 if (parent->algo->master_xfer) {295 if (muxc->mux_locked)296 priv->algo.master_xfer = i2c_mux_master_xfer;297 else298 priv->algo.master_xfer = __i2c_mux_master_xfer;299 }300 if (parent->algo->master_xfer_atomic)301 priv->algo.master_xfer_atomic = priv->algo.master_xfer;302 303 if (parent->algo->smbus_xfer) {304 if (muxc->mux_locked)305 priv->algo.smbus_xfer = i2c_mux_smbus_xfer;306 else307 priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;308 }309 if (parent->algo->smbus_xfer_atomic)310 priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer;311 312 priv->algo.functionality = i2c_mux_functionality;313 314 /* Now fill out new adapter structure */315 snprintf(priv->adap.name, sizeof(priv->adap.name),316 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);317 priv->adap.owner = THIS_MODULE;318 priv->adap.algo = &priv->algo;319 priv->adap.algo_data = priv;320 priv->adap.dev.parent = &parent->dev;321 priv->adap.retries = parent->retries;322 priv->adap.timeout = parent->timeout;323 priv->adap.quirks = parent->quirks;324 if (muxc->mux_locked)325 priv->adap.lock_ops = &i2c_mux_lock_ops;326 else327 priv->adap.lock_ops = &i2c_parent_lock_ops;328 329 /*330 * Try to populate the mux adapter's of_node, expands to331 * nothing if !CONFIG_OF.332 */333 if (muxc->dev->of_node) {334 struct device_node *dev_node = muxc->dev->of_node;335 struct device_node *mux_node, *child = NULL;336 u32 reg;337 338 if (muxc->arbitrator)339 mux_node = of_get_child_by_name(dev_node, "i2c-arb");340 else if (muxc->gate)341 mux_node = of_get_child_by_name(dev_node, "i2c-gate");342 else343 mux_node = of_get_child_by_name(dev_node, "i2c-mux");344 345 if (mux_node) {346 /* A "reg" property indicates an old-style DT entry */347 if (!of_property_read_u32(mux_node, "reg", ®)) {348 of_node_put(mux_node);349 mux_node = NULL;350 }351 }352 353 if (!mux_node)354 mux_node = of_node_get(dev_node);355 else if (muxc->arbitrator || muxc->gate)356 child = of_node_get(mux_node);357 358 if (!child) {359 for_each_child_of_node(mux_node, child) {360 ret = of_property_read_u32(child, "reg", ®);361 if (ret)362 continue;363 if (chan_id == reg)364 break;365 }366 }367 368 priv->adap.dev.of_node = child;369 of_node_put(mux_node);370 }371 372 /*373 * Associate the mux channel with an ACPI node.374 */375 if (has_acpi_companion(muxc->dev))376 acpi_preset_companion(&priv->adap.dev,377 ACPI_COMPANION(muxc->dev),378 chan_id);379 380 if (force_nr) {381 priv->adap.nr = force_nr;382 ret = i2c_add_numbered_adapter(&priv->adap);383 if (ret < 0) {384 dev_err(&parent->dev,385 "failed to add mux-adapter %u as bus %u (error=%d)\n",386 chan_id, force_nr, ret);387 goto err_free_priv;388 }389 } else {390 ret = i2c_add_adapter(&priv->adap);391 if (ret < 0) {392 dev_err(&parent->dev,393 "failed to add mux-adapter %u (error=%d)\n",394 chan_id, ret);395 goto err_free_priv;396 }397 }398 399 WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj,400 "mux_device"),401 "can't create symlink to mux device\n");402 403 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);404 WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj,405 symlink_name),406 "can't create symlink to channel %u\n", chan_id);407 dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",408 i2c_adapter_id(&priv->adap));409 410 muxc->adapter[muxc->num_adapters++] = &priv->adap;411 return 0;412 413err_free_priv:414 kfree(priv);415 return ret;416}417EXPORT_SYMBOL_GPL(i2c_mux_add_adapter);418 419void i2c_mux_del_adapters(struct i2c_mux_core *muxc)420{421 char symlink_name[20];422 423 while (muxc->num_adapters) {424 struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters];425 struct i2c_mux_priv *priv = adap->algo_data;426 struct device_node *np = adap->dev.of_node;427 428 muxc->adapter[muxc->num_adapters] = NULL;429 430 snprintf(symlink_name, sizeof(symlink_name),431 "channel-%u", priv->chan_id);432 sysfs_remove_link(&muxc->dev->kobj, symlink_name);433 434 sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");435 i2c_del_adapter(adap);436 of_node_put(np);437 kfree(priv);438 }439}440EXPORT_SYMBOL_GPL(i2c_mux_del_adapters);441 442MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");443MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");444MODULE_LICENSE("GPL v2");445