![Dustin Byford](/assets/img/avatar_default.png)
Although I2C mux devices are easily enumerated using ACPI (_HID/_CID or device property compatible string match), enumerating I2C client devices connected through an I2C mux needs a little extra work. This change implements a method for describing an I2C device hierarchy that includes mux devices by using an ACPI Device() for each mux channel along with an _ADR to set the channel number for the device. See Documentation/acpi/i2c-muxes.txt for a simple example. To make this work the ismt, i801, and designware pci/platform devs now share an ACPI companion with their I2C adapter dev similar to how it's done in OF. This is done on the assumption that power management functions will not be called directly on the I2C dev that is sharing the ACPI node. Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Dustin Byford <dustin@cumulusnetworks.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
228 lines
6.2 KiB
C
228 lines
6.2 KiB
C
/*
|
|
* 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>
|
|
#include <linux/of.h>
|
|
#include <linux/acpi.h>
|
|
|
|
/* multiplexer per channel data */
|
|
struct i2c_mux_priv {
|
|
struct i2c_adapter adap;
|
|
struct i2c_algorithm algo;
|
|
|
|
struct i2c_adapter *parent;
|
|
struct device *mux_dev;
|
|
void *mux_priv;
|
|
u32 chan_id;
|
|
|
|
int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id);
|
|
int (*deselect)(struct i2c_adapter *, void *mux_priv, 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_priv, priv->chan_id);
|
|
if (ret >= 0)
|
|
ret = __i2c_transfer(parent, msgs, num);
|
|
if (priv->deselect)
|
|
priv->deselect(parent, priv->mux_priv, 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_priv, 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_priv, 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);
|
|
}
|
|
|
|
/* Return all parent classes, merged */
|
|
static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
|
|
{
|
|
unsigned int class = 0;
|
|
|
|
do {
|
|
class |= parent->class;
|
|
parent = i2c_parent_is_i2c_adapter(parent);
|
|
} while (parent);
|
|
|
|
return class;
|
|
}
|
|
|
|
struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
|
|
struct device *mux_dev,
|
|
void *mux_priv, u32 force_nr, u32 chan_id,
|
|
unsigned int class,
|
|
int (*select) (struct i2c_adapter *,
|
|
void *, u32),
|
|
int (*deselect) (struct i2c_adapter *,
|
|
void *, u32))
|
|
{
|
|
struct i2c_mux_priv *priv;
|
|
char symlink_name[20];
|
|
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->mux_priv = mux_priv;
|
|
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.algo = &priv->algo;
|
|
priv->adap.algo_data = priv;
|
|
priv->adap.dev.parent = &parent->dev;
|
|
priv->adap.retries = parent->retries;
|
|
priv->adap.timeout = parent->timeout;
|
|
priv->adap.quirks = parent->quirks;
|
|
|
|
/* Sanity check on class */
|
|
if (i2c_mux_parent_classes(parent) & class)
|
|
dev_err(&parent->dev,
|
|
"Segment %d behind mux can't share classes with ancestors\n",
|
|
chan_id);
|
|
else
|
|
priv->adap.class = class;
|
|
|
|
/*
|
|
* Try to populate the mux adapter's of_node, expands to
|
|
* nothing if !CONFIG_OF.
|
|
*/
|
|
if (mux_dev->of_node) {
|
|
struct device_node *child;
|
|
u32 reg;
|
|
|
|
for_each_child_of_node(mux_dev->of_node, child) {
|
|
ret = of_property_read_u32(child, "reg", ®);
|
|
if (ret)
|
|
continue;
|
|
if (chan_id == reg) {
|
|
priv->adap.dev.of_node = child;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Associate the mux channel with an ACPI node.
|
|
*/
|
|
if (has_acpi_companion(mux_dev))
|
|
acpi_preset_companion(&priv->adap.dev, ACPI_COMPANION(mux_dev),
|
|
chan_id);
|
|
|
|
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;
|
|
}
|
|
|
|
WARN(sysfs_create_link(&priv->adap.dev.kobj, &mux_dev->kobj, "mux_device"),
|
|
"can't create symlink to mux device\n");
|
|
|
|
snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
|
|
WARN(sysfs_create_link(&mux_dev->kobj, &priv->adap.dev.kobj, symlink_name),
|
|
"can't create symlink for channel %u\n", chan_id);
|
|
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);
|
|
|
|
void i2c_del_mux_adapter(struct i2c_adapter *adap)
|
|
{
|
|
struct i2c_mux_priv *priv = adap->algo_data;
|
|
char symlink_name[20];
|
|
|
|
snprintf(symlink_name, sizeof(symlink_name), "channel-%u", priv->chan_id);
|
|
sysfs_remove_link(&priv->mux_dev->kobj, symlink_name);
|
|
|
|
sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
|
|
i2c_del_adapter(adap);
|
|
kfree(priv);
|
|
}
|
|
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");
|