i2c: import multiplexed I2C bus core support from linux kernel
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Antony Pavlov
Sascha Hauer
parent
a07652deb4
commit
c3859ce93c
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@ -6,4 +6,11 @@ if I2C
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source drivers/i2c/algos/Kconfig
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source drivers/i2c/busses/Kconfig
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config I2C_MUX
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tristate "I2C bus multiplexing support"
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help
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Say Y here if you want the I2C core to support the ability to
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handle multiplexed I2C bus topologies, by presenting each
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multiplexed segment as a I2C adapter.
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endif
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@ -1 +1,2 @@
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obj-$(CONFIG_I2C) += i2c.o i2c-smbus.o busses/ algos/
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obj-$(CONFIG_I2C_MUX) += i2c-mux.o
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@ -0,0 +1,148 @@
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/*
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* Multiplexed I2C bus driver.
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*
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* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
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* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
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* Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com>
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*
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* Ported to barebox from linux-v4.4-rc1
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* Copyright (C) 2015 Antony Pavlov <antonynpavlov@gmail.com>
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*
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* Simplifies access to complex multiplexed I2C bus topologies, by presenting
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* each multiplexed bus segment as an additional I2C adapter.
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* Supports multi-level mux'ing (mux behind a mux).
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*
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* Based on:
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* i2c-virt.c from Kumar Gala <galak@kernel.crashing.org>
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* i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
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* i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <common.h>
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#include <malloc.h>
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#include <xfuncs.h>
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#include <of.h>
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#include <i2c/i2c.h>
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#include <i2c/i2c-mux.h>
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/* multiplexer per channel data */
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struct i2c_mux_priv {
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struct i2c_adapter adap;
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struct i2c_adapter *parent;
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struct device_d *mux_dev;
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void *mux_priv;
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u32 chan_id;
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int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
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int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
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};
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static int i2c_mux_master_xfer(struct i2c_adapter *adap,
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struct i2c_msg msgs[], int num)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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struct i2c_adapter *parent = priv->parent;
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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_priv, priv->chan_id);
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if (ret >= 0)
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ret = parent->master_xfer(parent, msgs, num);
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if (priv->deselect)
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priv->deselect(parent, priv->mux_priv, priv->chan_id);
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return ret;
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}
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struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
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struct device_d *mux_dev,
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void *mux_priv, u32 force_nr, u32 chan_id,
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int (*select) (struct i2c_adapter *,
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void *, u32),
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int (*deselect) (struct i2c_adapter *,
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void *, u32))
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{
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struct i2c_mux_priv *priv;
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int ret;
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priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
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if (!priv)
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return NULL;
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/* Set up private adapter data */
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priv->parent = parent;
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priv->mux_dev = mux_dev;
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priv->mux_priv = mux_priv;
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priv->chan_id = chan_id;
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priv->select = select;
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priv->deselect = deselect;
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/* Need to do algo dynamically because we don't know ahead
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* of time what sort of physical adapter we'll be dealing with.
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*/
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if (parent->master_xfer)
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priv->adap.master_xfer = i2c_mux_master_xfer;
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/* Now fill out new adapter structure */
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priv->adap.algo_data = priv;
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priv->adap.dev.parent = &parent->dev;
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priv->adap.retries = parent->retries;
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/*
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* Try to populate the mux adapter's device_node, expands to
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* nothing if !CONFIG_OF.
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*/
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if (mux_dev->device_node) {
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struct device_node *child;
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u32 reg;
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for_each_child_of_node(mux_dev->device_node, child) {
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ret = of_property_read_u32(child, "reg", ®);
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if (ret)
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continue;
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if (chan_id == reg) {
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priv->adap.dev.device_node = child;
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break;
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}
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}
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}
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if (force_nr) {
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priv->adap.nr = force_nr;
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} else {
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priv->adap.nr = -1;
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}
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ret = i2c_add_numbered_adapter(&priv->adap);
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if (ret < 0) {
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dev_err(&parent->dev,
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"failed to add mux-adapter (error=%d)\n",
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ret);
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kfree(priv);
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return NULL;
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}
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dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
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i2c_adapter_id(&priv->adap));
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return &priv->adap;
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}
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EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
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void i2c_del_mux_adapter(struct i2c_adapter *adap)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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free(priv);
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}
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EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
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MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
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MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
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MODULE_LICENSE("GPL v2");
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@ -0,0 +1,40 @@
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/*
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*
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* i2c-mux.h - functions for the i2c-bus mux support
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*
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* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
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* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
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* Michael Lawnick <michael.lawnick.ext@nsn.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#ifndef _LINUX_I2C_MUX_H
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#define _LINUX_I2C_MUX_H
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/*
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* Called to create a i2c bus on a multiplexed bus segment.
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* The mux_dev and chan_id parameters are passed to the select
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* and deselect callback functions to perform hardware-specific
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* mux control.
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*/
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struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
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struct device_d *mux_dev,
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void *mux_priv, u32 force_nr, u32 chan_id,
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int (*select) (struct i2c_adapter *,
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void *mux_dev, u32 chan_id),
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int (*deselect) (struct i2c_adapter *,
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void *mux_dev, u32 chan_id));
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void i2c_del_mux_adapter(struct i2c_adapter *adap);
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#endif /* _LINUX_I2C_MUX_H */
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@ -245,7 +245,11 @@ extern struct list_head i2c_adapter_list;
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extern struct i2c_client *
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i2c_new_dummy(struct i2c_adapter *adap, u16 address);
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/* Return the adapter number for a specific adapter */
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static inline int i2c_adapter_id(struct i2c_adapter *adap)
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{
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return adap->nr;
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}
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extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);
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extern int i2c_master_send(struct i2c_client *client, const char *buf, int count);
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