From 0826374bff57411d239f2fcb15da3c35af0a93cd Mon Sep 17 00:00:00 2001 From: Michael Lawnick Date: Wed, 11 Aug 2010 18:21:02 +0200 Subject: i2c: Multiplexed I2C bus core support Add multiplexed bus core support. I2C multiplexer and switches like pca954x get instantiated as new adapters per port. Signed-off-by: Michael Lawnick Acked-by: Rodolfo Giometti Signed-off-by: Jean Delvare --- drivers/i2c/i2c-mux.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 drivers/i2c/i2c-mux.c (limited to 'drivers/i2c/i2c-mux.c') diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c new file mode 100644 index 000000000000..d32a4843fc3a --- /dev/null +++ b/drivers/i2c/i2c-mux.c @@ -0,0 +1,165 @@ +/* + * 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 + +/* multiplexer per channel data */ +struct i2c_mux_priv { + struct i2c_adapter adap; + struct i2c_algorithm algo; + + struct i2c_adapter *parent; + void *mux_dev; /* the mux chip/device */ + u32 chan_id; /* the channel id */ + + int (*select)(struct i2c_adapter *, void *mux_dev, u32 chan_id); + int (*deselect)(struct i2c_adapter *, void *mux_dev, 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_dev, priv->chan_id); + if (ret >= 0) + ret = parent->algo->master_xfer(parent, msgs, num); + if (priv->deselect) + priv->deselect(parent, priv->mux_dev, 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_dev, 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_dev, 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); +} + +struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, + void *mux_dev, u32 force_nr, u32 chan_id, + 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_dev = mux_dev; + priv->chan_id = chan_id; + priv->select = select; + priv->deselect = deselect; + + /* 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.id = parent->id; + priv->adap.algo = &priv->algo; + priv->adap.algo_data = priv; + priv->adap.dev.parent = &parent->dev; + + 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)); + + return &priv->adap; +} +EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); + +int i2c_del_mux_adapter(struct i2c_adapter *adap) +{ + struct i2c_mux_priv *priv = adap->algo_data; + int ret; + + ret = i2c_del_adapter(adap); + if (ret < 0) + return ret; + kfree(priv); + + return 0; +} +EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); + +MODULE_AUTHOR("Rodolfo Giometti "); +MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); +MODULE_LICENSE("GPL v2"); -- cgit v1.2.3-59-g8ed1b