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-rw-r--r--drivers/i2c/Kconfig11
-rw-r--r--drivers/i2c/Makefile1
-rw-r--r--drivers/i2c/i2c-core.c64
-rw-r--r--drivers/i2c/i2c-dev.c40
-rw-r--r--drivers/i2c/i2c-mux.c165
5 files changed, 273 insertions, 8 deletions
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index d06083fdffbb..efb48ad1ba34 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -47,6 +47,17 @@ config I2C_CHARDEV
This support is also available as a module. If so, the module
will be called i2c-dev.
+config I2C_MUX
+ tristate "I2C bus multiplexing support"
+ depends on EXPERIMENTAL
+ help
+ Say Y here if you want the I2C core to support the ability to
+ handle multiplexed I2C bus topologies, by presenting each
+ multiplexed segment as a I2C adapter.
+
+ This support is also available as a module. If so, the module
+ will be called i2c-mux.
+
config I2C_HELPER_AUTO
bool "Autoselect pertinent helper modules"
default y
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index a7d9b4be9bb3..f363258daa3d 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
obj-$(CONFIG_I2C) += i2c-core.o
obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o
obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
+obj-$(CONFIG_I2C_MUX) += i2c-mux.o
obj-y += algos/ busses/
ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 97f96b66653c..6649176de940 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -20,7 +20,9 @@
/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
- Jean Delvare <khali@linux-fr.org> */
+ Jean Delvare <khali@linux-fr.org>
+ Mux support by Rodolfo Giometti <giometti@enneenne.com> and
+ Michael Lawnick <michael.lawnick.ext@nsn.com> */
#include <linux/module.h>
#include <linux/kernel.h>
@@ -423,10 +425,48 @@ static int __i2c_check_addr_busy(struct device *dev, void *addrp)
return 0;
}
+/* walk up mux tree */
+static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+ int result;
+
+ result = device_for_each_child(&adapter->dev, &addr,
+ __i2c_check_addr_busy);
+
+ if (!result && i2c_parent_is_i2c_adapter(adapter))
+ result = i2c_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ return result;
+}
+
+/* recurse down mux tree */
+static int i2c_check_mux_children(struct device *dev, void *addrp)
+{
+ int result;
+
+ if (dev->type == &i2c_adapter_type)
+ result = device_for_each_child(dev, addrp,
+ i2c_check_mux_children);
+ else
+ result = __i2c_check_addr_busy(dev, addrp);
+
+ return result;
+}
+
static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
{
- return device_for_each_child(&adapter->dev, &addr,
- __i2c_check_addr_busy);
+ int result = 0;
+
+ if (i2c_parent_is_i2c_adapter(adapter))
+ result = i2c_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ if (!result)
+ result = device_for_each_child(&adapter->dev, &addr,
+ i2c_check_mux_children);
+
+ return result;
}
/**
@@ -435,7 +475,10 @@ static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
*/
void i2c_lock_adapter(struct i2c_adapter *adapter)
{
- rt_mutex_lock(&adapter->bus_lock);
+ if (i2c_parent_is_i2c_adapter(adapter))
+ i2c_lock_adapter(to_i2c_adapter(adapter->dev.parent));
+ else
+ rt_mutex_lock(&adapter->bus_lock);
}
EXPORT_SYMBOL_GPL(i2c_lock_adapter);
@@ -445,7 +488,10 @@ EXPORT_SYMBOL_GPL(i2c_lock_adapter);
*/
static int i2c_trylock_adapter(struct i2c_adapter *adapter)
{
- return rt_mutex_trylock(&adapter->bus_lock);
+ if (i2c_parent_is_i2c_adapter(adapter))
+ return i2c_trylock_adapter(to_i2c_adapter(adapter->dev.parent));
+ else
+ return rt_mutex_trylock(&adapter->bus_lock);
}
/**
@@ -454,7 +500,10 @@ static int i2c_trylock_adapter(struct i2c_adapter *adapter)
*/
void i2c_unlock_adapter(struct i2c_adapter *adapter)
{
- rt_mutex_unlock(&adapter->bus_lock);
+ if (i2c_parent_is_i2c_adapter(adapter))
+ i2c_unlock_adapter(to_i2c_adapter(adapter->dev.parent));
+ else
+ rt_mutex_unlock(&adapter->bus_lock);
}
EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
@@ -743,10 +792,11 @@ static const struct attribute_group *i2c_adapter_attr_groups[] = {
NULL
};
-static struct device_type i2c_adapter_type = {
+struct device_type i2c_adapter_type = {
.groups = i2c_adapter_attr_groups,
.release = i2c_adapter_dev_release,
};
+EXPORT_SYMBOL_GPL(i2c_adapter_type);
#ifdef CONFIG_I2C_COMPAT
static struct class_compat *i2c_adapter_compat_class;
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 0b0427f7d348..5f3a52d517c3 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -189,12 +189,50 @@ static int i2cdev_check(struct device *dev, void *addrp)
return dev->driver ? -EBUSY : 0;
}
+/* walk up mux tree */
+static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+ int result;
+
+ result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+
+ if (!result && i2c_parent_is_i2c_adapter(adapter))
+ result = i2cdev_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ return result;
+}
+
+/* recurse down mux tree */
+static int i2cdev_check_mux_children(struct device *dev, void *addrp)
+{
+ int result;
+
+ if (dev->type == &i2c_adapter_type)
+ result = device_for_each_child(dev, addrp,
+ i2cdev_check_mux_children);
+ else
+ result = i2cdev_check(dev, addrp);
+
+ return result;
+}
+
/* This address checking function differs from the one in i2c-core
in that it considers an address with a registered device, but no
driver bound to it, as NOT busy. */
static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
- return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+ int result = 0;
+
+ if (i2c_parent_is_i2c_adapter(adapter))
+ result = i2cdev_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ if (!result)
+ result = device_for_each_child(&adapter->dev, &addr,
+ i2cdev_check_mux_children);
+
+ return result;
}
static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
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 <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>
+
+/* 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 <giometti@linux.it>");
+MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
+MODULE_LICENSE("GPL v2");

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