/* * Multiplexed I2C bus driver. * * Copyright (c) 2008-2009 Rodolfo Giometti * Copyright (c) 2008-2009 Eurotech S.p.A. * Copyright (c) 2009-2010 NSN GmbH & Co KG * * 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 * i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc. * i2c-virtual.c from Brian Kuschak * * 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 #include #include #include #include #include #include /* multiplexer per channel data */ struct i2c_mux_priv_old { void *mux_priv; int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id); int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id); }; 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_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; } /* 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 int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan) { struct i2c_mux_priv_old *priv = i2c_mux_priv(muxc); return priv->select(muxc->parent, priv->mux_priv, chan); } static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan) { struct i2c_mux_priv_old *priv = i2c_mux_priv(muxc); return priv->deselect(muxc->parent, priv->mux_priv, chan); } struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, struct device *mux_dev, void *mux_priv, u32 force_nr, u32 chan_id, unsigned int class, int (*select) (struct i2c_adapter *, void *, u32), int (*deselect) (struct i2c_adapter *, void *, u32)) { struct i2c_mux_core *muxc; struct i2c_mux_priv_old *priv; int ret; muxc = i2c_mux_alloc(parent, mux_dev, 1, sizeof(*priv), 0, i2c_mux_select, i2c_mux_deselect); if (!muxc) return NULL; priv = i2c_mux_priv(muxc); priv->select = select; priv->deselect = deselect; priv->mux_priv = mux_priv; ret = i2c_mux_add_adapter(muxc, force_nr, chan_id, class); if (ret) { devm_kfree(mux_dev, muxc); return NULL; } return muxc->adapter[0]; } EXPORT_SYMBOL_GPL(i2c_add_mux_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; muxc->select = select; muxc->deselect = deselect; muxc->max_adapters = max_adapters; return muxc; } EXPORT_SYMBOL_GPL(i2c_mux_alloc); 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) priv->algo.master_xfer = i2c_mux_master_xfer; if (parent->algo->smbus_xfer) 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; /* 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 *child; u32 reg; for_each_child_of_node(muxc->dev->of_node, child) { ret = of_property_read_u32(child, "reg", ®); if (ret) continue; if (chan_id == reg) { priv->adap.dev.of_node = child; break; } } } /* * 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); } else { ret = i2c_add_adapter(&priv->adap); } if (ret < 0) { dev_err(&parent->dev, "failed to add mux-adapter (error=%d)\n", ret); kfree(priv); return ret; } 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; } 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; 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); kfree(priv); } } EXPORT_SYMBOL_GPL(i2c_mux_del_adapters); void i2c_del_mux_adapter(struct i2c_adapter *adap) { struct i2c_mux_priv *priv = adap->algo_data; struct i2c_mux_core *muxc = priv->muxc; i2c_mux_del_adapters(muxc); devm_kfree(muxc->dev, muxc); } EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); MODULE_AUTHOR("Rodolfo Giometti "); MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); MODULE_LICENSE("GPL v2");