text: /****************************************************************************
   * drivers/ioexpander/mcp23x17.c
   *
   * 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 <assert.h>
  #include <errno.h>
  #include <debug.h>
  
  #include <nuttx/irq.h>
  #include <nuttx/i2c/i2c_master.h>
  #include <nuttx/kmalloc.h>
  #include <nuttx/ioexpander/ioexpander.h>
  
  #include "mcp23x17.h"
  
  #if defined(CONFIG_IOEXPANDER_MCP23X17)
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  #ifndef CONFIG_I2C
  #  warning I2C support is required (CONFIG_I2C)
  #endif
  
  #if (!defined CONFIG_SCHED_WORKQUEUE) && (defined CONFIG_MCP23X17_INT_ENABLE)
  #  error Work queue support is required (CONFIG_SCHED_WORKQUEUE)
  #endif
  
  #if (!defined CONFIG_SCHED_HPWORK) && (defined CONFIG_MCP23X17_INT_ENABLE)
  #  error High-Priority Work support is required (CONFIG_SCHED_HPWORK)
  #endif
  
  /****************************************************************************
   * Private Function Prototypes
   ****************************************************************************/
  
  static inline int mcp23x17_write(FAR struct mcp23x17_dev_s *priv,
               FAR const uint8_t *wbuffer, int wbuflen);
  static inline int mcp23x17_writeread(FAR struct mcp23x17_dev_s *priv,
               FAR const uint8_t *wbuffer, int wbuflen, FAR uint8_t *rbuffer,
               int rbuflen);
  static int mcp23x17_direction(FAR struct ioexpander_dev_s *dev, uint8_t pin,
               int dir);
  static int mcp23x17_option(FAR struct ioexpander_dev_s *dev, uint8_t pin,
               int opt, void *val);
  static int mcp23x17_writepin(FAR struct ioexpander_dev_s *dev, uint8_t pin,
               bool value);
  static int mcp23x17_readpin(FAR struct ioexpander_dev_s *dev, uint8_t pin,
               FAR bool *value);
  static int mcp23x17_readbuf(FAR struct ioexpander_dev_s *dev, uint8_t pin,
               FAR bool *value);
  #ifdef CONFIG_IOEXPANDER_MULTIPIN
  static int mcp23x17_multiwritepin(FAR struct ioexpander_dev_s *dev,
               FAR uint8_t *pins, FAR bool *values, int count);
  static int mcp23x17_multireadpin(FAR struct ioexpander_dev_s *dev,
               FAR uint8_t *pins, FAR bool *values, int count);
  static int mcp23x17_multireadbuf(FAR struct ioexpander_dev_s *dev,
               FAR uint8_t *pins, FAR bool *values, int count);
  #endif
  #ifdef CONFIG_IOEXPANDER_INT_ENABLE
  static FAR void *mcp23x17_attach(FAR struct ioexpander_dev_s *dev,
               ioe_pinset_t pinset, ioe_callback_t callback, FAR void *arg);
  static int mcp23x17_detach(FAR struct ioexpander_dev_s *dev,
               FAR void *handle);
  #endif
  
  /****************************************************************************
   * Private Data
   ****************************************************************************/
  
  #ifndef CONFIG_MCP23X17_MULTIPLE
  /* If only a single MCP23X17 device is supported, then the driver state
   * structure may as well be pre-allocated.
   */
  
  static struct mcp23x17_dev_s g_mcp23x17;
  
  /* Otherwise, we will need to maintain allocated driver instances in a list */
  
  #else
  static struct mcp23x17_dev_s *g_mcp23x17list;
  #endif
  
  /* I/O expander vtable */
  
  static const struct ioexpander_ops_s g_mcp23x17_ops =
  {
    mcp23x17_direction,
    mcp23x17_option,
    mcp23x17_writepin,
    mcp23x17_readpin,
    mcp23x17_readbuf
  #ifdef CONFIG_IOEXPANDER_MULTIPIN
    , mcp23x17_multiwritepin
    , mcp23x17_multireadpin
    , mcp23x17_multireadbuf
  #endif
  #ifdef CONFIG_IOEXPANDER_INT_ENABLE
    , mcp23x17_attach
    , mcp23x17_detach
  #endif
  };
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: mcp23x17_lock
   *
   * Description:
   *   Get exclusive access to the MCP23X17
   *
   ****************************************************************************/
  
  static int mcp23x17_lock(FAR struct mcp23x17_dev_s *priv)
  {
    return nxsem_wait_uninterruptible(&priv->exclsem);
  }
  
  #define mcp23x17_unlock(p) nxsem_post(&(p)->exclsem)
  
  /****************************************************************************
   * Name: mcp23x17_write
   *
   * Description:
   *   Write to the I2C device.
   *
   ****************************************************************************/
  
  static inline int mcp23x17_write(FAR struct mcp23x17_dev_s *priv,
                                   FAR const uint8_t *wbuffer, int wbuflen)
  {
    struct i2c_msg_s msg;
    int ret;
  
    /* Setup for the transfer */
  
    msg.frequency = priv->config->frequency;
    msg.addr      = priv->config->address;
    msg.flags     = 0;
    msg.buffer    = (FAR uint8_t *)wbuffer;  /* Override const */
    msg.length    = wbuflen;
  
    /* Then perform the transfer. */
  
    ret = I2C_TRANSFER(priv->i2c, &msg, 1);
    return (ret >= 0) ? OK : ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_writeread
   *
   * Description:
   *   Write to then read from the I2C device.
   *
   ****************************************************************************/
  
  static inline int mcp23x17_writeread(FAR struct mcp23x17_dev_s *priv,
                                       FAR const uint8_t *wbuffer, int wbuflen,
                                       FAR uint8_t *rbuffer, int rbuflen)
  {
    struct i2c_config_s config;
  
    /* Set up the configuration and perform the write-read operation */
  
    config.frequency = priv->config->frequency;
    config.address   = priv->config->address;
    config.addrlen   = 7;
  
    return i2c_writeread(priv->i2c, &config, wbuffer, wbuflen,
                         rbuffer, rbuflen);
  }
  
  /****************************************************************************
   * Name: mcp23x17_setbit
   *
   * Description:
   *  Write a bit in a register pair
   *
   ****************************************************************************/
  
  static int mcp23x17_setbit(FAR struct mcp23x17_dev_s *priv, uint8_t addr,
                             uint8_t pin, int bitval)
  {
    uint8_t buf[2];
    int ret;
  
    if (pin > 15)
      {
        return -ENXIO;
      }
    else if (pin > 7)
      {
        addr += 1;
        pin  -= 8;
      }
  
    buf[0] = addr;
  
  #ifdef CONFIG_MCP23X17_SHADOW_MODE
    /* Get the shadowed register value */
  
    buf[1] = priv->sreg[addr];
  
  #else
    /* Get the register value from the IO-Expander */
  
    ret = mcp23x17_writeread(priv, &buf[0], 1, &buf[1], 1);
    if (ret < 0)
      {
        return ret;
      }
  #endif
  
    if (bitval)
      {
        buf[1] |= (1 << pin);
      }
    else
      {
        buf[1] &= ~(1 << pin);
      }
  
  #ifdef CONFIG_MCP23X17_SHADOW_MODE
    /* Save the new register value in the shadow register */
  
    priv->sreg[addr] = buf[1];
  #endif
  
    ret = mcp23x17_write(priv, buf, 2);
  #ifdef CONFIG_MCP23X17_RETRY
    if (ret != OK)
      {
        /* Try again (only once) */
  
        ret = mcp23x17_write(priv, buf, 2);
      }
  #endif
  
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_getbit
   *
   * Description:
   *  Get a bit from a register pair
   *
   ****************************************************************************/
  
  static int mcp23x17_getbit(FAR struct mcp23x17_dev_s *priv, uint8_t addr,
                             uint8_t pin, FAR bool *val)
  {
    uint8_t buf;
    int ret;
  
    if (pin > 15)
      {
        return -ENXIO;
      }
    else if (pin > 7)
      {
        addr += 1;
        pin  -= 8;
      }
  
    ret = mcp23x17_writeread(priv, &addr, 1, &buf, 1);
    if (ret < 0)
      {
        return ret;
      }
  
  #ifdef CONFIG_MCP23X17_SHADOW_MODE
    /* Save the new register value in the shadow register */
  
    priv->sreg[addr] = buf;
  #endif
  
    *val = (buf >> pin) & 1;
    return OK;
  }
  
  /****************************************************************************
   * Name: mcp23x17_direction
   *
   * Description:
   *   Set the direction of an ioexpander pin. Required.
   *
   * Input Parameters:
   *   dev - Device-specific state data
   *   pin - The index of the pin to alter in this call
   *   dir - One of the IOEXPANDER_DIRECTION_ macros
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_direction(FAR struct ioexpander_dev_s *dev, uint8_t pin,
                               int direction)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret;
  
    if (direction != IOEXPANDER_DIRECTION_IN &&
        direction != IOEXPANDER_DIRECTION_OUT)
      {
        return -EINVAL;
      }
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    ret = mcp23x17_setbit(priv, MCP23X17_IODIRA, pin,
                          (direction == IOEXPANDER_DIRECTION_IN));
    mcp23x17_unlock(priv);
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_option
   *
   * Description:
   *   Set pin options. Required.
   *   Since all IO expanders have various pin options, this API allows setting
   *     pin options in a flexible way.
   *
   * Input Parameters:
   *   dev - Device-specific state data
   *   pin - The index of the pin to alter in this call
   *   opt - One of the IOEXPANDER_OPTION_ macros
   *   val - The option's value
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_option(FAR struct ioexpander_dev_s *dev, uint8_t pin,
                             int opt, FAR void *val)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret = -EINVAL;
  
    if (opt == IOEXPANDER_OPTION_INVERT)
      {
        int ival = (int)((intptr_t)val);
  
        /* Get exclusive access to the MCP23X17 */
  
        ret = mcp23x17_lock(priv);
        if (ret < 0)
          {
            return ret;
          }
  
        ret = mcp23x17_setbit(priv, MCP23X17_IPOLA, pin, ival);
        mcp23x17_unlock(priv);
      }
  
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_writepin
   *
   * Description:
   *   Set the pin level. Required.
   *
   * Input Parameters:
   *   dev - Device-specific state data
   *   pin - The index of the pin to alter in this call
   *   val - The pin level. Usually TRUE will set the pin high,
   *         except if OPTION_INVERT has been set on this pin.
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_writepin(FAR struct ioexpander_dev_s *dev, uint8_t pin,
                               bool value)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    ret = mcp23x17_setbit(priv, MCP23X17_GPIOA, pin, value);
    mcp23x17_unlock(priv);
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_readpin
   *
   * Description:
   *   Read the actual PIN level. This can be different from the last value
   *      written to this pin. Required.
   *
   * Input Parameters:
   *   dev    - Device-specific state data
   *   pin    - The index of the pin
   *   valptr - Pointer to a buffer where the pin level is stored. Usually TRUE
   *            if the pin is high, except if OPTION_INVERT has been set on
   *            this pin.
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_readpin(FAR struct ioexpander_dev_s *dev, uint8_t pin,
                              FAR bool *value)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    ret = mcp23x17_getbit(priv, MCP23X17_GPIOA, pin, value);
  
    mcp23x17_unlock(priv);
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_readbuf
   *
   * Description:
   *   Read the buffered pin level.
   *   This can be different from the actual pin state. Required.
   *
   * Input Parameters:
   *   dev    - Device-specific state data
   *   pin    - The index of the pin
   *   valptr - Pointer to a buffer where the level is stored.
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_readbuf(FAR struct ioexpander_dev_s *dev, uint8_t pin,
                              FAR bool *value)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    ret = mcp23x17_getbit(priv, MCP23X17_GPIOA, pin, value);
    mcp23x17_unlock(priv);
    return ret;
  }
  
  #ifdef CONFIG_IOEXPANDER_MULTIPIN
  
  /****************************************************************************
   * Name: mcp23x17_getmultibits
   *
   * Description:
   *  Read multiple bits from MCP23X17 registers.
   *
   ****************************************************************************/
  
  static int mcp23x17_getmultibits(FAR struct mcp23x17_dev_s *priv,
                                   uint8_t addr,
                                   FAR uint8_t *pins,
                                   FAR bool *values,
                                   int count)
  {
    uint8_t buf[2];
    int ret = OK;
    int i;
    int index;
    int pin;
  
    ret = mcp23x17_writeread(priv, &addr, 1, buf, 2);
    if (ret < 0)
      {
        return ret;
      }
  
  #ifdef CONFIG_MCP23X17_SHADOW_MODE
    /* Save the new register value in the shadow register */
  
    priv->sreg[addr]     = buf[0];
    priv->sreg[addr + 1] = buf[1];
  #endif
  
    /* Read the requested bits */
  
    for (i = 0; i < count; i++)
      {
        index = 0;
        pin   = pins[i];
        if (pin > 15)
          {
            return -ENXIO;
          }
        else if (pin > 7)
          {
            index = 1;
            pin  -= 8;
          }
  
        values[i] = (buf[index] >> pin) & 1;
      }
  
    return OK;
  }
  
  /****************************************************************************
   * Name: mcp23x17_multiwritepin
   *
   * Description:
   *   Set the pin level for multiple pins. This routine may be faster than
   *   individual pin accesses. Optional.
   *
   * Input Parameters:
   *   dev - Device-specific state data
   *   pins - The list of pin indexes to alter in this call
   *   val - The list of pin levels.
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_multiwritepin(FAR struct ioexpander_dev_s *dev,
                                    FAR uint8_t *pins, FAR bool *values,
                                    int count)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    uint8_t addr = MCP23X17_GPIOA;
    uint8_t buf[3];
    int ret;
    int i;
    int index;
    int pin;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    /* Start by reading both registers, whatever the pins to change. We could
     * attempt to read one port only if all pins were on the same port, but
     * this would not save much.
     */
  
  #ifndef CONFIG_MCP23X17_SHADOW_MODE
    ret = mcp23x17_writeread(priv, &addr, 1, &buf[1], 2);
    if (ret < 0)
      {
        mcp23x17_unlock(priv);
        return ret;
      }
  #else
    /* In Shadow-Mode we "read" the pin status from the shadow registers */
  
    buf[1] = priv->sreg[addr];
    buf[2] = priv->sreg[addr + 1];
  #endif
  
    /* Apply the user defined changes */
  
    for (i = 0; i < count; i++)
      {
        index = 1;
        pin = pins[i];
        if (pin > 15)
          {
            mcp23x17_unlock(priv);
            return -ENXIO;
          }
        else if (pin > 7)
          {
            index = 2;
            pin  -= 8;
          }
  
        if (values[i])
          {
            buf[index] |= (1 << pin);
          }
        else
          {
            buf[index] &= ~(1 << pin);
          }
      }
  
    /* Now write back the new pins states */
  
    buf[0] = addr;
  #ifdef CONFIG_MCP23X17_SHADOW_MODE
    /* Save the new register values in the shadow register */
  
    priv->sreg[addr]     = buf[1];
    priv->sreg[addr + 1] = buf[2];
  #endif
    ret = mcp23x17_write(priv, buf, 3);
  
    mcp23x17_unlock(priv);
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_multireadpin
   *
   * Description:
   *   Read the actual level for multiple pins. This routine may be faster than
   *   individual pin accesses. Optional.
   *
   * Input Parameters:
   *   dev    - Device-specific state data
   *   pin    - The list of pin indexes to read
   *   valptr - Pointer to a buffer where the pin levels are stored.
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_multireadpin(FAR struct ioexpander_dev_s *dev,
                                   FAR uint8_t *pins, FAR bool *values,
                                   int count)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    ret = mcp23x17_getmultibits(priv, MCP23X17_GPIOA,
                                pins, values, count);
    mcp23x17_unlock(priv);
    return ret;
  }
  
  /****************************************************************************
   * Name: mcp23x17_multireadbuf
   *
   * Description:
   *   Read the buffered level of multiple pins. This routine may be faster
   *   than individual pin accesses. Optional.
   *
   * Input Parameters:
   *   dev    - Device-specific state data
   *   pin    - The index of the pin
   *   valptr - Pointer to a buffer where the buffered levels are stored.
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_multireadbuf(FAR struct ioexpander_dev_s *dev,
                                   FAR uint8_t *pins, FAR bool *values,
                                   int count)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    int ret;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    ret = mcp23x17_getmultibits(priv, MCP23X17_GPIOA,
                                pins, values, count);
    mcp23x17_unlock(priv);
    return ret;
  }
  
  #endif
  
  #ifdef CONFIG_MCP23X17_INT_ENABLE
  
  /****************************************************************************
   * Name: mcp23x17_attach
   *
   * Description:
   *   Attach and enable a pin interrupt callback function.
   *
   * Input Parameters:
   *   dev      - Device-specific state data
   *   pinset   - The set of pin events that will generate the callback
   *   callback - The pointer to callback function.  NULL will detach the
   *              callback.
   *   arg      - User-provided callback argument
   *
   * Returned Value:
   *   A non-NULL handle value is returned on success.  This handle may be
   *   used later to detach and disable the pin interrupt.
   *
   ****************************************************************************/
  
  static FAR void *mcp23x17_attach(FAR struct ioexpander_dev_s *dev,
                                   ioe_pinset_t pinset,
                                   ioe_callback_t callback,
                                   FAR void *arg)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    FAR void *handle = NULL;
    int i;
    int ret;
  
    /* Get exclusive access to the MCP23X17 */
  
    ret = mcp23x17_lock(priv);
    if (ret < 0)
      {
        return ret;
      }
  
    /* Find and available in entry in the callback table */
  
    for (i = 0; i < CONFIG_MCP23X17_INT_NCALLBACKS; i++)
      {
        /* Is this entry available (i.e., no callback attached) */
  
        if (priv->cb[i].cbfunc == NULL)
          {
            /* Yes.. use this entry */
  
            priv->cb[i].pinset = pinset;
            priv->cb[i].cbfunc = callback;
            priv->cb[i].cbarg  = arg;
            handle             = &priv->cb[i];
            break;
          }
      }
  
    /* Add this callback to the table */
  
    mcp23x17_unlock(priv);
    return handle;
  }
  
  /****************************************************************************
   * Name: mcp23x17_detach
   *
   * Description:
   *   Detach and disable a pin interrupt callback function.
   *
   * Input Parameters:
   *   dev      - Device-specific state data
   *   handle   - The non-NULL opaque value return by mcp23x17_attch()
   *
   * Returned Value:
   *   0 on success, else a negative error code
   *
   ****************************************************************************/
  
  static int mcp23x17_detach(FAR struct ioexpander_dev_s *dev,
                             FAR void *handle)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)dev;
    FAR struct mcp23x17_callback_s *cb =
      (FAR struct mcp23x17_callback_s *)handle;
  
    DEBUGASSERT(priv != NULL && cb != NULL);
    DEBUGASSERT((uintptr_t)cb >= (uintptr_t)&priv->cb[0] &&
                (uintptr_t)cb <=
                (uintptr_t)&priv->cb[CONFIG_TCA64XX_INT_NCALLBACKS - 1]);
    UNUSED(priv);
  
    cb->pinset = 0;
    cb->cbfunc = NULL;
    cb->cbarg  = NULL;
    return OK;
  }
  
  /****************************************************************************
   * Name: mcp23x17_irqworker
   *
   * Description:
   *   Handle GPIO interrupt events (this function actually executes in the
   *   context of the worker thread).
   *
   ****************************************************************************/
  
  static void mcp23x17_irqworker(void *arg)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)arg;
    uint8_t addr = MCP23X17_GPIOA;
    uint8_t buf[2];
    ioe_pinset_t pinset;
    int ret;
    int i;
  
    /* Read inputs */
  
    ret = mcp23x17_writeread(priv, &addr, 1, buf, 2);
    if (ret == OK)
      {
  #ifdef CONFIG_MCP23X17_SHADOW_MODE
        /* Don't forget to update the shadow registers at this point */
  
        priv->sreg[addr]     = buf[0];
        priv->sreg[addr + 1] = buf[1];
  #endif
        /* Create a 16-bit pinset */
  
        pinset = ((unsigned int)buf[0] << 8) | buf[1];
  
        /* Perform pin interrupt callbacks */
  
        for (i = 0; i < CONFIG_MCP23X17_INT_NCALLBACKS; i++)
          {
            /* Is this entry valid (i.e., callback attached)?  If so, did
             * any of the requested pin interrupts occur?
             */
  
            if (priv->cb[i].cbfunc != NULL)
              {
                /* Did any of the requested pin interrupts occur? */
  
                ioe_pinset_t match = pinset & priv->cb[i].pinset;
                if (match != 0)
                  {
                    /* Yes.. perform the callback */
  
                    priv->cb[i].cbfunc(&priv->dev, match,
                                      priv->cb[i].cbarg);
                  }
              }
          }
      }
  
    /* Re-enable interrupts */
  
    priv->config->enable(priv->config, TRUE);
  }
  
  /****************************************************************************
   * Name: mcp23x17_interrupt
   *
   * Description:
   *   Handle GPIO interrupt events (this function executes in the
   *   context of the interrupt).
   *
   ****************************************************************************/
  
  static int mcp23x17_interrupt(int irq, FAR void *context, FAR void *arg)
  {
    FAR struct mcp23x17_dev_s *priv = (FAR struct mcp23x17_dev_s *)arg;
  
    /* In complex environments, we cannot do I2C transfers from the interrupt
     * handler because semaphores are probably used to lock the I2C bus.  In
     * this case, we will defer processing to the worker thread.  This is also
     * much kinder in the use of system resources and is, therefore, probably
     * a good thing to do in any event.
     */
  
    /* Notice that further GPIO interrupts are disabled until the work is
     * actually performed.  This is to prevent overrun of the worker thread.
     * Interrupts are re-enabled in mcp23x17_irqworker() when the work is
     * completed.
     */
  
    if (work_available(&priv->work))
      {
        priv->config->enable(priv->config, FALSE);
        work_queue(HPWORK, &priv->work, mcp23x17_irqworker,
                   (FAR void *)priv, 0);
      }
  
    return OK;
  }
  
  #endif
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: mcp23x17_initialize
   *
   * Description:
   *   Initialize a MCP23X17 I2C device.
   *
   * TODO: Add support for more than one device.
   *
   ****************************************************************************/
  
  FAR struct ioexpander_dev_s *mcp23x17_initialize(
                                FAR struct i2c_master_s *i2cdev,
                                FAR struct mcp23x17_config_s *config)
  {
    FAR struct mcp23x17_dev_s *priv;
  
    DEBUGASSERT(i2cdev != NULL && config != NULL);
  
  #ifdef CONFIG_MCP23X17_MULTIPLE
    /* Allocate the device state structure */
  
    priv = (FAR struct mcp23x17_dev_s *)
      kmm_zalloc(sizeof(struct mcp23x17_dev_s));
    if (!priv)
      {
        return NULL;
      }
  
    /* And save the device structure in the list of MCP23X17 so that we can
     * find it later.
     */
  
    priv->flink = g_mcp23x17list;
    g_mcp23x17list = priv;
  
  #else
    /* Use the global MCP23X17 driver instance */
  
    priv = &g_mcp23x17;
  #endif
  
    /* Initialize the device state structure */
  
    priv->i2c     = i2cdev;
    priv->dev.ops = &g_mcp23x17_ops;
    priv->config  = config;
  
  #ifdef CONFIG_MCP23X17_INT_ENABLE
    priv->config->attach(priv->config, mcp23x17_interrupt, priv);
    priv->config->enable(priv->config, TRUE);
  #endif
  
    nxsem_init(&priv->exclsem, 0, 1);
    return &priv->dev;
  }
  
  #endif /* CONFIG_IOEXPANDER_MCP23X17 */
  