/* * Multiplexed I2C bus driver. * * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it> * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it> * Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com> * * Simplifies access to complex multiplexed I2C bus topologies, by presenting * each multiplexed bus segment as an additional I2C adapter. * Supports multi-level mux'ing (mux behind a mux). * * Based on: * i2c-virt.c from Kumar Gala <galak@kernel.crashing.org> * i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc. * i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com> * * This file is licensed under the terms of the GNU General Public * License version 2. This program is licensed "as is" without any * warranty of any kind, whether express or implied. */ #include <linux/acpi.h> #include <linux/i2c.h> #include <linux/i2c-mux.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> #include <linux/slab.h> /* multiplexer per channel data */ struct i2c_mux_priv { struct i2c_adapter adap; struct i2c_algorithm algo; struct i2c_mux_core *muxc; u32 chan_id; }; static int __i2c_mux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { struct i2c_mux_priv *priv = adap->algo_data; struct i2c_mux_core *muxc = priv->muxc; struct i2c_adapter *parent = muxc->parent; int ret; /* Switch to the right mux port and perform the transfer. */ ret = muxc->select(muxc, priv->chan_id); if (ret >= 0) ret = __i2c_transfer(parent, msgs, num); if (muxc->deselect) muxc->deselect(muxc, priv->chan_id); return ret; } static int i2c_mux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { struct i2c_mux_priv *priv = adap->algo_data; struct i2c_mux_core *muxc = priv->muxc; struct i2c_adapter *parent = muxc->parent; int ret; /* Switch to the right mux port and perform the transfer. */ ret = muxc->select(muxc, priv->chan_id); if (ret >= 0) ret = i2c_transfer(parent, msgs, num); if (muxc->deselect) muxc->deselect(muxc, priv->chan_id); return ret; } static int __i2c_mux_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data) { struct i2c_mux_priv *priv = adap->algo_data; struct i2c_mux_core *muxc = priv->muxc; struct i2c_adapter *parent = muxc->parent; int ret; /* Select the right mux port and perform the transfer. */ ret = muxc->select(muxc, priv->chan_id); if (ret >= 0) ret = parent->algo->smbus_xfer(parent, addr, flags, read_write, command, size, data); if (muxc->deselect) muxc->deselect(muxc, priv->chan_id); return ret; } static int i2c_mux_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data) { struct i2c_mux_priv *priv = adap->algo_data; struct i2c_mux_core *muxc = priv->muxc; struct i2c_adapter *parent = muxc->parent; int ret; /* Select the right mux port and perform the transfer. */ ret = muxc->select(muxc, priv->chan_id); if (ret >= 0) ret = i2c_smbus_xfer(parent, addr, flags, read_write, command, size, data); if (muxc->deselect) muxc->deselect(muxc, priv->chan_id); return ret; } /* Return the parent's functionality */ static u32 i2c_mux_functionality(struct i2c_adapter *adap) { struct i2c_mux_priv *priv = adap->algo_data; struct i2c_adapter *parent = priv->muxc->parent; return parent->algo->functionality(parent); } /* Return all parent classes, merged */ static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent) { unsigned int class = 0; do { class |= parent->class; parent = i2c_parent_is_i2c_adapter(parent); } while (parent); return class; } static void i2c_mux_lock_bus(struct i2c_adapter *adapter, unsigned int flags) { struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; rt_mutex_lock(&parent->mux_lock); if (!(flags & I2C_LOCK_ROOT_ADAPTER)) return; i2c_lock_bus(parent, flags); } static int i2c_mux_trylock_bus(struct i2c_adapter *adapter, unsigned int flags) { struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; if (!rt_mutex_trylock(&parent->mux_lock)) return 0; /* mux_lock not locked, failure */ if (!(flags & I2C_LOCK_ROOT_ADAPTER)) return 1; /* we only want mux_lock, success */ if (i2c_trylock_bus(parent, flags)) return 1; /* parent locked too, success */ rt_mutex_unlock(&parent->mux_lock); return 0; /* parent not locked, failure */ } static void i2c_mux_unlock_bus(struct i2c_adapter *adapter, unsigned int flags) { struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; if (flags & I2C_LOCK_ROOT_ADAPTER) i2c_unlock_bus(parent, flags); rt_mutex_unlock(&parent->mux_lock); } static void i2c_parent_lock_bus(struct i2c_adapter *adapter, unsigned int flags) { struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; rt_mutex_lock(&parent->mux_lock); i2c_lock_bus(parent, flags); } static int i2c_parent_trylock_bus(struct i2c_adapter *adapter, unsigned int flags) { struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; if (!rt_mutex_trylock(&parent->mux_lock)) return 0; /* mux_lock not locked, failure */ if (i2c_trylock_bus(parent, flags)) return 1; /* parent locked too, success */ rt_mutex_unlock(&parent->mux_lock); return 0; /* parent not locked, failure */ } static void i2c_parent_unlock_bus(struct i2c_adapter *adapter, unsigned int flags) { struct i2c_mux_priv *priv = adapter->algo_data; struct i2c_adapter *parent = priv->muxc->parent; i2c_unlock_bus(parent, flags); rt_mutex_unlock(&parent->mux_lock); } struct i2c_adapter *i2c_root_adapter(struct device *dev) { struct device *i2c; struct i2c_adapter *i2c_root; /* * Walk up the device tree to find an i2c adapter, indicating * that this is an i2c client device. Check all ancestors to * handle mfd devices etc. */ for (i2c = dev; i2c; i2c = i2c->parent) { if (i2c->type == &i2c_adapter_type) break; } if (!i2c) return NULL; /* Continue up the tree to find the root i2c adapter */ i2c_root = to_i2c_adapter(i2c); while (i2c_parent_is_i2c_adapter(i2c_root)) i2c_root = i2c_parent_is_i2c_adapter(i2c_root); return i2c_root; } EXPORT_SYMBOL_GPL(i2c_root_adapter); struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent, struct device *dev, int max_adapters, int sizeof_priv, u32 flags, int (*select)(struct i2c_mux_core *, u32), int (*deselect)(struct i2c_mux_core *, u32)) { struct i2c_mux_core *muxc; muxc = devm_kzalloc(dev, sizeof(*muxc) + max_adapters * sizeof(muxc->adapter[0]) + sizeof_priv, GFP_KERNEL); if (!muxc) return NULL; if (sizeof_priv) muxc->priv = &muxc->adapter[max_adapters]; muxc->parent = parent; muxc->dev = dev; if (flags & I2C_MUX_LOCKED) muxc->mux_locked = true; if (flags & I2C_MUX_ARBITRATOR) muxc->arbitrator = true; if (flags & I2C_MUX_GATE) muxc->gate = true; muxc->select = select; muxc->deselect = deselect; muxc->max_adapters = max_adapters; return muxc; } EXPORT_SYMBOL_GPL(i2c_mux_alloc); static const struct i2c_lock_operations i2c_mux_lock_ops = { .lock_bus = i2c_mux_lock_bus, .trylock_bus = i2c_mux_trylock_bus, .unlock_bus = i2c_mux_unlock_bus, }; static const struct i2c_lock_operations i2c_parent_lock_ops = { .lock_bus = i2c_parent_lock_bus, .trylock_bus = i2c_parent_trylock_bus, .unlock_bus = i2c_parent_unlock_bus, }; int i2c_mux_add_adapter(struct i2c_mux_core *muxc, u32 force_nr, u32 chan_id, unsigned int class) { struct i2c_adapter *parent = muxc->parent; struct i2c_mux_priv *priv; char symlink_name[20]; int ret; if (muxc->num_adapters >= muxc->max_adapters) { dev_err(muxc->dev, "No room for more i2c-mux adapters\n"); return -EINVAL; } priv = kzalloc(sizeof(*priv), GFP_KERNEL); if (!priv) return -ENOMEM; /* Set up private adapter data */ priv->muxc = muxc; priv->chan_id = chan_id; /* Need to do algo dynamically because we don't know ahead * of time what sort of physical adapter we'll be dealing with. */ if (parent->algo->master_xfer) { if (muxc->mux_locked) priv->algo.master_xfer = i2c_mux_master_xfer; else priv->algo.master_xfer = __i2c_mux_master_xfer; } if (parent->algo->smbus_xfer) { if (muxc->mux_locked) priv->algo.smbus_xfer = i2c_mux_smbus_xfer; else priv->algo.smbus_xfer = __i2c_mux_smbus_xfer; } priv->algo.functionality = i2c_mux_functionality; /* Now fill out new adapter structure */ snprintf(priv->adap.name, sizeof(priv->adap.name), "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id); priv->adap.owner = THIS_MODULE; priv->adap.algo = &priv->algo; priv->adap.algo_data = priv; priv->adap.dev.parent = &parent->dev; priv->adap.retries = parent->retries; priv->adap.timeout = parent->timeout; priv->adap.quirks = parent->quirks; if (muxc->mux_locked) priv->adap.lock_ops = &i2c_mux_lock_ops; else priv->adap.lock_ops = &i2c_parent_lock_ops; /* Sanity check on class */ if (i2c_mux_parent_classes(parent) & class) dev_err(&parent->dev, "Segment %d behind mux can't share classes with ancestors\n", chan_id); else priv->adap.class = class; /* * Try to populate the mux adapter's of_node, expands to * nothing if !CONFIG_OF. */ if (muxc->dev->of_node) { struct device_node *dev_node = muxc->dev->of_node; struct device_node *mux_node, *child = NULL; u32 reg; if (muxc->arbitrator) mux_node = of_get_child_by_name(dev_node, "i2c-arb"); else if (muxc->gate) mux_node = of_get_child_by_name(dev_node, "i2c-gate"); else mux_node = of_get_child_by_name(dev_node, "i2c-mux"); if (mux_node) { /* A "reg" property indicates an old-style DT entry */ if (!of_property_read_u32(mux_node, "reg", ®)) { of_node_put(mux_node); mux_node = NULL; } } if (!mux_node) mux_node = of_node_get(dev_node); else if (muxc->arbitrator || muxc->gate) child = of_node_get(mux_node); if (!child) { for_each_child_of_node(mux_node, child) { ret = of_property_read_u32(child, "reg", ®); if (ret) continue; if (chan_id == reg) break; } } priv->adap.dev.of_node = child; of_node_put(mux_node); } /* * Associate the mux channel with an ACPI node. */ if (has_acpi_companion(muxc->dev)) acpi_preset_companion(&priv->adap.dev, ACPI_COMPANION(muxc->dev), chan_id); if (force_nr) { priv->adap.nr = force_nr; ret = i2c_add_numbered_adapter(&priv->adap); if (ret < 0) { dev_err(&parent->dev, "failed to add mux-adapter %u as bus %u (error=%d)\n", chan_id, force_nr, ret); goto err_free_priv; } } else { ret = i2c_add_adapter(&priv->adap); if (ret < 0) { dev_err(&parent->dev, "failed to add mux-adapter %u (error=%d)\n", chan_id, ret); goto err_free_priv; } } WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj, "mux_device"), "can't create symlink to mux device\n"); snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id); WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj, symlink_name), "can't create symlink for channel %u\n", chan_id); dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", i2c_adapter_id(&priv->adap)); muxc->adapter[muxc->num_adapters++] = &priv->adap; return 0; err_free_priv: kfree(priv); return ret; } EXPORT_SYMBOL_GPL(i2c_mux_add_adapter); void i2c_mux_del_adapters(struct i2c_mux_core *muxc) { char symlink_name[20]; while (muxc->num_adapters) { struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters]; struct i2c_mux_priv *priv = adap->algo_data; struct device_node *np = adap->dev.of_node; muxc->adapter[muxc->num_adapters] = NULL; snprintf(symlink_name, sizeof(symlink_name), "channel-%u", priv->chan_id); sysfs_remove_link(&muxc->dev->kobj, symlink_name); sysfs_remove_link(&priv->adap.dev.kobj, "mux_device"); i2c_del_adapter(adap); of_node_put(np); kfree(priv); } } EXPORT_SYMBOL_GPL(i2c_mux_del_adapters); MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); MODULE_LICENSE("GPL v2");