| /* |
| * 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/kernel.h> |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/i2c.h> |
| #include <linux/i2c-mux.h> |
| #include <linux/of.h> |
| #include <linux/of_i2c.h> |
| |
| /* multiplexer per channel data */ |
| struct i2c_mux_priv { |
| struct i2c_adapter adap; |
| struct i2c_algorithm algo; |
| |
| struct i2c_adapter *parent; |
| void *mux_priv; /* the mux chip/device */ |
| u32 chan_id; /* the channel id */ |
| |
| int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id); |
| int (*deselect)(struct i2c_adapter *, void *mux_priv, 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_adapter *parent = priv->parent; |
| int ret; |
| |
| /* Switch to the right mux port and perform the transfer. */ |
| |
| ret = priv->select(parent, priv->mux_priv, priv->chan_id); |
| if (ret >= 0) |
| ret = parent->algo->master_xfer(parent, msgs, num); |
| if (priv->deselect) |
| priv->deselect(parent, priv->mux_priv, 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_adapter *parent = priv->parent; |
| int ret; |
| |
| /* Select the right mux port and perform the transfer. */ |
| |
| ret = priv->select(parent, priv->mux_priv, priv->chan_id); |
| if (ret >= 0) |
| ret = parent->algo->smbus_xfer(parent, addr, flags, |
| read_write, command, size, data); |
| if (priv->deselect) |
| priv->deselect(parent, priv->mux_priv, 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->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; |
| } |
| |
| 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_priv *priv; |
| int ret; |
| |
| priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL); |
| if (!priv) |
| return NULL; |
| |
| /* Set up private adapter data */ |
| priv->parent = parent; |
| priv->mux_priv = mux_priv; |
| priv->chan_id = chan_id; |
| priv->select = select; |
| |
| /* 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; |
| |
| /* 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 (mux_dev->of_node) { |
| struct device_node *child; |
| bool enable_deselect; |
| u32 reg; |
| |
| for_each_child_of_node(mux_dev->of_node, child) { |
| ret = of_property_read_u32(child, "reg", ®); |
| if (ret) |
| continue; |
| if (chan_id == reg) { |
| priv->adap.dev.of_node = child; |
| enable_deselect = of_property_read_bool(child, |
| "i2c-mux,deselect-on-exit"); |
| if (enable_deselect) |
| priv->deselect = deselect; |
| break; |
| } |
| } |
| } else { |
| priv->deselect = deselect; |
| } |
| |
| 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 NULL; |
| } |
| |
| dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", |
| i2c_adapter_id(&priv->adap)); |
| |
| of_i2c_register_devices(&priv->adap); |
| |
| return &priv->adap; |
| } |
| EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); |
| |
| void i2c_del_mux_adapter(struct i2c_adapter *adap) |
| { |
| struct i2c_mux_priv *priv = adap->algo_data; |
| |
| i2c_del_adapter(adap); |
| kfree(priv); |
| } |
| EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); |
| |
| MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); |
| MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); |
| MODULE_LICENSE("GPL v2"); |