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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 <ml.lawnick@gmx.de> Acked-by: Rodolfo Giometti <giometti@linux.it> Signed-off-by: Jean Delvare <khali@linux-fr.org>
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Michael Lawnick
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Jean Delvare
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Aug 11, 2010
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,165 @@ | ||
| /* | ||
| * 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. | ||
| */ | ||
|
|
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| #include <linux/kernel.h> | ||
| #include <linux/module.h> | ||
| #include <linux/slab.h> | ||
| #include <linux/i2c.h> | ||
| #include <linux/i2c-mux.h> | ||
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| /* multiplexer per channel data */ | ||
| struct i2c_mux_priv { | ||
| struct i2c_adapter adap; | ||
| struct i2c_algorithm algo; | ||
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| struct i2c_adapter *parent; | ||
| void *mux_dev; /* the mux chip/device */ | ||
| u32 chan_id; /* the channel id */ | ||
|
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| 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; | ||
|
|
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| /* Switch to the right mux port and perform the transfer. */ | ||
|
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| 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); | ||
|
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| return ret; | ||
| } | ||
|
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| 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; | ||
|
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| /* Select the right mux port and perform the transfer. */ | ||
|
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| 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); | ||
|
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| return ret; | ||
| } | ||
|
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| /* 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; | ||
|
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| return parent->algo->functionality(parent); | ||
| } | ||
|
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| 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; | ||
|
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| priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL); | ||
| if (!priv) | ||
| return NULL; | ||
|
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| /* Set up private adapter data */ | ||
| priv->parent = parent; | ||
| priv->mux_dev = mux_dev; | ||
| priv->chan_id = chan_id; | ||
| priv->select = select; | ||
| priv->deselect = deselect; | ||
|
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| /* 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; | ||
|
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| /* 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; | ||
|
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| 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; | ||
| } | ||
|
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| dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", | ||
| i2c_adapter_id(&priv->adap)); | ||
|
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| return &priv->adap; | ||
| } | ||
| EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); | ||
|
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| int i2c_del_mux_adapter(struct i2c_adapter *adap) | ||
| { | ||
| struct i2c_mux_priv *priv = adap->algo_data; | ||
| int ret; | ||
|
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| ret = i2c_del_adapter(adap); | ||
| if (ret < 0) | ||
| return ret; | ||
| kfree(priv); | ||
|
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| return 0; | ||
| } | ||
| EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); | ||
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| MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); | ||
| MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); | ||
| MODULE_LICENSE("GPL v2"); |
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