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>
This commit is contained in:
Michael Lawnick
Jean Delvare
parent
dafc50d141
commit
0826374bff
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@ -47,6 +47,17 @@ config I2C_CHARDEV
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This support is also available as a module. If so, the module
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will be called i2c-dev.
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config I2C_MUX
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tristate "I2C bus multiplexing support"
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depends on EXPERIMENTAL
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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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This support is also available as a module. If so, the module
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will be called i2c-mux.
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config I2C_HELPER_AUTO
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bool "Autoselect pertinent helper modules"
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default y
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@ -6,6 +6,7 @@ obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
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obj-$(CONFIG_I2C) += i2c-core.o
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obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o
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obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
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obj-$(CONFIG_I2C_MUX) += i2c-mux.o
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obj-y += algos/ busses/
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ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
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@ -20,7 +20,9 @@
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/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
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All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
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SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
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Jean Delvare <khali@linux-fr.org> */
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Jean Delvare <khali@linux-fr.org>
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Mux support by Rodolfo Giometti <giometti@enneenne.com> and
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Michael Lawnick <michael.lawnick.ext@nsn.com> */
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#include <linux/module.h>
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#include <linux/kernel.h>
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@ -423,10 +425,48 @@ static int __i2c_check_addr_busy(struct device *dev, void *addrp)
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return 0;
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}
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/* walk up mux tree */
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static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
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{
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int result;
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result = device_for_each_child(&adapter->dev, &addr,
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__i2c_check_addr_busy);
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if (!result && i2c_parent_is_i2c_adapter(adapter))
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result = i2c_check_mux_parents(
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to_i2c_adapter(adapter->dev.parent), addr);
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return result;
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}
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/* recurse down mux tree */
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static int i2c_check_mux_children(struct device *dev, void *addrp)
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{
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int result;
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if (dev->type == &i2c_adapter_type)
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result = device_for_each_child(dev, addrp,
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i2c_check_mux_children);
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else
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result = __i2c_check_addr_busy(dev, addrp);
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return result;
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}
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static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
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{
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return device_for_each_child(&adapter->dev, &addr,
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__i2c_check_addr_busy);
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int result = 0;
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if (i2c_parent_is_i2c_adapter(adapter))
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result = i2c_check_mux_parents(
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to_i2c_adapter(adapter->dev.parent), addr);
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if (!result)
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result = device_for_each_child(&adapter->dev, &addr,
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i2c_check_mux_children);
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return result;
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}
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/**
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@ -435,7 +475,10 @@ static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
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*/
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void i2c_lock_adapter(struct i2c_adapter *adapter)
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{
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rt_mutex_lock(&adapter->bus_lock);
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if (i2c_parent_is_i2c_adapter(adapter))
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i2c_lock_adapter(to_i2c_adapter(adapter->dev.parent));
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else
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rt_mutex_lock(&adapter->bus_lock);
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}
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EXPORT_SYMBOL_GPL(i2c_lock_adapter);
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@ -445,7 +488,10 @@ EXPORT_SYMBOL_GPL(i2c_lock_adapter);
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*/
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static int i2c_trylock_adapter(struct i2c_adapter *adapter)
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{
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return rt_mutex_trylock(&adapter->bus_lock);
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if (i2c_parent_is_i2c_adapter(adapter))
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return i2c_trylock_adapter(to_i2c_adapter(adapter->dev.parent));
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else
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return rt_mutex_trylock(&adapter->bus_lock);
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}
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/**
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@ -454,7 +500,10 @@ static int i2c_trylock_adapter(struct i2c_adapter *adapter)
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*/
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void i2c_unlock_adapter(struct i2c_adapter *adapter)
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{
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rt_mutex_unlock(&adapter->bus_lock);
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if (i2c_parent_is_i2c_adapter(adapter))
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i2c_unlock_adapter(to_i2c_adapter(adapter->dev.parent));
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else
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rt_mutex_unlock(&adapter->bus_lock);
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}
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EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
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@ -743,10 +792,11 @@ static const struct attribute_group *i2c_adapter_attr_groups[] = {
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NULL
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};
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static struct device_type i2c_adapter_type = {
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struct device_type i2c_adapter_type = {
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.groups = i2c_adapter_attr_groups,
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.release = i2c_adapter_dev_release,
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};
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EXPORT_SYMBOL_GPL(i2c_adapter_type);
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#ifdef CONFIG_I2C_COMPAT
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static struct class_compat *i2c_adapter_compat_class;
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@ -189,12 +189,50 @@ static int i2cdev_check(struct device *dev, void *addrp)
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return dev->driver ? -EBUSY : 0;
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}
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/* walk up mux tree */
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static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
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{
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int result;
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result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
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if (!result && i2c_parent_is_i2c_adapter(adapter))
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result = i2cdev_check_mux_parents(
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to_i2c_adapter(adapter->dev.parent), addr);
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return result;
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}
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/* recurse down mux tree */
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static int i2cdev_check_mux_children(struct device *dev, void *addrp)
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{
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int result;
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if (dev->type == &i2c_adapter_type)
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result = device_for_each_child(dev, addrp,
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i2cdev_check_mux_children);
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else
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result = i2cdev_check(dev, addrp);
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return result;
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}
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/* This address checking function differs from the one in i2c-core
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in that it considers an address with a registered device, but no
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driver bound to it, as NOT busy. */
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static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
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{
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return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
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int result = 0;
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if (i2c_parent_is_i2c_adapter(adapter))
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result = i2cdev_check_mux_parents(
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to_i2c_adapter(adapter->dev.parent), addr);
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if (!result)
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result = device_for_each_child(&adapter->dev, &addr,
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i2cdev_check_mux_children);
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return result;
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}
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static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
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@ -0,0 +1,165 @@
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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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* 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 <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/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_algorithm algo;
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struct i2c_adapter *parent;
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void *mux_dev; /* the mux chip/device */
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u32 chan_id; /* the channel id */
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int (*select)(struct i2c_adapter *, void *mux_dev, u32 chan_id);
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int (*deselect)(struct i2c_adapter *, void *mux_dev, 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_dev, priv->chan_id);
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if (ret >= 0)
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ret = parent->algo->master_xfer(parent, msgs, num);
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if (priv->deselect)
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priv->deselect(parent, priv->mux_dev, priv->chan_id);
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return ret;
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}
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static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
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u16 addr, unsigned short flags,
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char read_write, u8 command,
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int size, union i2c_smbus_data *data)
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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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/* Select the right mux port and perform the transfer. */
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ret = priv->select(parent, priv->mux_dev, priv->chan_id);
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if (ret >= 0)
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ret = parent->algo->smbus_xfer(parent, addr, flags,
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read_write, command, size, data);
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if (priv->deselect)
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priv->deselect(parent, priv->mux_dev, priv->chan_id);
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return ret;
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}
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/* Return the parent's functionality */
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static u32 i2c_mux_functionality(struct i2c_adapter *adap)
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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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return parent->algo->functionality(parent);
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}
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struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
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void *mux_dev, 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->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->algo->master_xfer)
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priv->algo.master_xfer = i2c_mux_master_xfer;
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if (parent->algo->smbus_xfer)
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priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
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priv->algo.functionality = i2c_mux_functionality;
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/* Now fill out new adapter structure */
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snprintf(priv->adap.name, sizeof(priv->adap.name),
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"i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
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priv->adap.owner = THIS_MODULE;
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priv->adap.id = parent->id;
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priv->adap.algo = &priv->algo;
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priv->adap.algo_data = priv;
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priv->adap.dev.parent = &parent->dev;
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if (force_nr) {
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priv->adap.nr = force_nr;
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ret = i2c_add_numbered_adapter(&priv->adap);
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} else {
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ret = i2c_add_adapter(&priv->adap);
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}
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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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int 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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int ret;
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ret = i2c_del_adapter(adap);
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if (ret < 0)
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return ret;
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kfree(priv);
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return 0;
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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 +1,46 @@
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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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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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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#ifdef __KERNEL__
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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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void *mux_dev, 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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int i2c_del_mux_adapter(struct i2c_adapter *adap);
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#endif /* __KERNEL__ */
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#endif /* _LINUX_I2C_MUX_H */
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@ -37,6 +37,7 @@
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#include <linux/of.h> /* for struct device_node */
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extern struct bus_type i2c_bus_type;
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extern struct device_type i2c_adapter_type;
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/* --- General options ------------------------------------------------ */
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@ -383,6 +384,13 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
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dev_set_drvdata(&dev->dev, data);
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}
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static inline int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
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{
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return adapter->dev.parent != NULL
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&& adapter->dev.parent->bus == &i2c_bus_type
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&& adapter->dev.parent->type == &i2c_adapter_type;
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}
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/* Adapter locking functions, exported for shared pin cases */
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void i2c_lock_adapter(struct i2c_adapter *);
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void i2c_unlock_adapter(struct i2c_adapter *);
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