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incubator-nuttx/drivers/i2c/tca9548a.c

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/****************************************************************************
* drivers/i2c/tca9548a.c
* Driver for the TCA9448A i2c multiplexer
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <fixedmath.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/i2c/i2c_master.h>
#include <nuttx/i2c/tca9548a.h>
#ifdef CONFIG_I2CMULTIPLEXER_TCA9548A
#ifndef CONFIG_TCA9548A_I2C_FREQUENCY
# define CONFIG_TCA9548A_I2C_FREQUENCY 400000
#endif
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* I2C Helpers */
static int tca9548a_write_config(FAR struct tca9548a_dev_s *priv,
uint8_t regvalue);
static int tca9548a_read_config(FAR struct tca9548a_dev_s *priv,
FAR uint8_t *regvalue);
/* Other helpers */
static int tca9548a_select_channel(FAR struct tca9548a_dev_s *priv,
uint8_t val);
/* I2C multiplexer vtable */
static int tca9548a_transfer_on_channel (FAR struct i2c_master_s *dev,
FAR struct i2c_msg_s *msgs,
int count);
#ifdef CONFIG_I2C_RESET
static int tca9548a_reset_on_channel (FAR struct i2c_master_s *dev);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static const struct i2c_ops_s g_i2cmux_ops =
{
tca9548a_transfer_on_channel
#ifdef CONFIG_I2C_RESET
, tca9548a_reset_on_channel
#endif
};
/****************************************************************************
* Private Types
****************************************************************************/
struct i2c_channel_dev_s
{
FAR struct i2c_master_s vi2c; /* Nested structure to allow casting as
* public i2c master */
uint8_t channel; /* Associated channel on the mux */
FAR struct tca9548a_dev_s *dev; /* Associated device */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: tca9548a_write_config
*
* Description:
* Write to the mux register of TCA9548A.
*
* Input Parameters:
* priv - A pointer to the TCA9548A device structure.
* regvalue - The value that will be written.
*
* Returned Value:
* OK on success or a negative error.
*
****************************************************************************/
static int tca9548a_write_config(FAR struct tca9548a_dev_s *priv,
uint8_t regvalue)
{
struct i2c_config_s iconf;
int ret;
iconf.frequency = CONFIG_TCA9548A_I2C_FREQUENCY;
iconf.address = priv->addr;
iconf.addrlen = 7;
ret = i2c_write(priv->i2c, &iconf, &regvalue, 1);
i2cinfo("Write to address 0x%02X; register value: 0x%02x ret: %d\n",
priv->addr, regvalue, ret);
return ret;
}
/****************************************************************************
* Name: tca9548a_read_config
*
* Description:
* Read the mux register from TCA9548A.
*
* Input Parameters:
* priv - A pointer to the TCA9548A device structure.
* regvalue - A pointer to a buffer into which data will be received.
*
* Returned Value:
* OK on success or a negative error.
*
****************************************************************************/
static int tca9548a_read_config(FAR struct tca9548a_dev_s *priv,
FAR uint8_t *regvalue)
{
struct i2c_config_s iconf;
int ret;
iconf.frequency = CONFIG_TCA9548A_I2C_FREQUENCY;
iconf.address = priv->addr;
iconf.addrlen = 7;
ret = i2c_read(priv->i2c, &iconf, regvalue, 1);
i2cinfo("Read from address: 0x%02X; register value: 0x%02x ret: %d\n",
priv->addr, *regvalue, ret);
return ret;
}
/****************************************************************************
* Name: tca9548a_select_channel
*
* Description:
* Helper function to select a channel in the TCA9548A. The TCA9548A allows
* to select more than 1 channel at same time, but here we are forcing it
* to only enable a single channel by time. It will avoid collision in case
* where two devices with same address are connected to two channels.
*
* Input Parameters:
* dev - Pointer to the (virtual) i2c_master_s.
* val - The channel to be selected.
*
* Returned Value:
* OK on success or a negative error.
*
****************************************************************************/
static int tca9548a_select_channel(FAR struct tca9548a_dev_s *priv,
uint8_t val)
{
int ret;
if (val > TCA9548A_SEL_CH7)
{
/* channel not existent/supported */
return -EINVAL;
}
if ((priv->state & (1 << val)) != 0)
{
/* channel already selected */
return OK;
}
/* Try to setup the new channel */
ret = tca9548a_write_config(priv, 1 << val);
if (ret < 0)
{
return -ECOMM;
}
/* Modify state. Selecting a channel always enables the device */
priv->state = 1 << val;
return OK;
}
/****************************************************************************
* Name: tca9548a_transfer_on_channel
*
* Description:
* Transfer an I2C message over the TCA9548A multiplexer. This function is
* attached to the virtual i2c_master ".transfer()" pointer. This way every
* time an I2C message is sent it is called and it starts sending a command
* to TCA9548A setup the right channel defined to this i2c_master. All the
* expected messages are then transferred to the I2C device connected the
* this selected channel.
*
* Input Parameters:
* dev - Pointer to the (virtual) i2c_master_s.
* msgs - the i2c message to be send to a device connected on TCA9548A.
* count - Number of messages to be send.
*
* Returned Value:
* OK on success or a negative error.
*
****************************************************************************/
static int tca9548a_transfer_on_channel(FAR struct i2c_master_s *dev,
FAR struct i2c_msg_s *msgs,
int count)
{
FAR struct i2c_channel_dev_s *ch_dev = (FAR struct i2c_channel_dev_s *)dev;
FAR struct tca9548a_dev_s *priv = ch_dev->dev;
int ret;
/* select the mux channel */
if (tca9548a_select_channel(priv, ch_dev->channel) != OK)
{
i2cerr("Could not select proper mux channel\n");
return -ECOMM; /* Signal error condition */
}
/* Resume the i2c transfer to the device connected to the mux channel */
ret = I2C_TRANSFER(priv->i2c, msgs, count);
i2cinfo("Selected channel %d and resumed transfer. Result: %d\n",
ch_dev->channel, ret);
return ret;
}
/****************************************************************************
* Name: tca9548a_reset_on_channel
*
* Description:
* Reset the I2C device connected to the current channel
*
* Input Parameters:
* dev - Pointer to the (virtual) i2c_master_s.
*
* Returned Value:
* OK on success or a negative error.
*
****************************************************************************/
#ifdef CONFIG_I2C_RESET
static int tca9548a_reset_on_channel(FAR struct i2c_master_s *dev)
{
FAR struct i2c_channel_dev_s *ch_dev = (struct i2c_channel_dev_s *)dev;
FAR struct tca9548a_dev_s *priv = ch_dev->dev;
int channel = ch_dev->channel;
int ret;
/* select the mux channel */
if (tca9548a_select_channel(priv, channel) != OK)
{
i2cerr("Could not select proper mux channel\n");
return -ECOMM; /* signal error condition */
}
/* resume the i2c reset for the device connected to the mux channel */
ret = I2C_RESET(priv->i2c);
return ret;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: tca9548a_lower_half
*
* Description:
* Initialize the lower half of the TCA9548A by creating an i2c_master_s
* for the virtual i2c master and link it to the associated TCA9548A and
* its channel.
*
* Input Parameters:
* dev - Pointer to the associated TCA9548A
* channel - The channel number as defined in tca9548a.h
*
* Returned Value:
* Common i2c multiplexer device instance; NULL on failure.
*
****************************************************************************/
FAR struct i2c_master_s *
tca9548a_lower_half(FAR struct tca9548a_dev_s *dev, uint8_t channel)
{
FAR struct i2c_channel_dev_s *channel_dev;
/* Sanity check */
DEBUGASSERT(dev != NULL);
/* Initialize the i2c_channel_dev_s device structure */
channel_dev = (FAR struct i2c_channel_dev_s *)
kmm_malloc(sizeof(struct i2c_channel_dev_s));
if (channel_dev == NULL)
{
i2cerr("ERROR: Failed to allocate i2c channel lower half instance\n");
return NULL;
}
/* set vi2c ops to their implementations */
channel_dev->vi2c.ops = &g_i2cmux_ops;
/* save state variables */
channel_dev->dev = dev;
channel_dev->channel = channel;
return &channel_dev->vi2c;
}
/****************************************************************************
* Name: tca9548a_initialize
*
* Description:
* Initialize the TCA9548A device.
*
* Input Parameters:
* i2c - An instance of the I2C interface to use to communicate with
* TCA9548A
* addr - The I2C address of the TCA9548A. The base I2C address of the
* TCA9548A is 0x70.
*
* Returned Value:
* Common i2c multiplexer device instance; NULL on failure.
*
****************************************************************************/
FAR struct tca9548a_dev_s *
tca9548a_initialize(FAR struct i2c_master_s *i2c, uint8_t addr)
{
FAR struct tca9548a_dev_s *priv;
/* Sanity check */
DEBUGASSERT(i2c != NULL);
/* Initialize the TCA9548A device structure */
priv = (FAR struct tca9548a_dev_s *)
kmm_malloc(sizeof(struct tca9548a_dev_s));
if (priv == NULL)
{
i2cerr("ERROR: Failed to allocate instance\n");
return NULL;
}
priv->i2c = i2c;
priv->addr = addr;
priv->state = 0x00;
if (tca9548a_read_config(priv, &priv->state) != OK)
{
i2cerr("Could not read initial state from the device\n");
kmm_free(priv);
return NULL; /* signal error condition */
}
i2cinfo("Initial device state: %d\n", priv->state);
if (tca9548a_select_channel(priv, TCA9548A_SEL_CH0) != OK)
{
i2cerr("Could not select mux channel 0\n");
kmm_free(priv);
return NULL; /* signal error condition */
}
i2cinfo("TCA9548A (addr=0x%02x) set up with channel %d\n", priv->addr,
TCA9548A_SEL_CH0);
return priv;
}
#endif /* CONFIG_I2CMULTIPLEXER_TCA9548A */
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