nuttx/drivers/usbhost/usbhost_devaddr.c

/*******************************************************************************
 * drivers/usbhost/usbhost_devaddr.c
 * Manage USB device addresses
 *
 *   Copyright (C) 2013, 2015 Gregory Nutt. All rights reserved.
 *   Authors: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 *******************************************************************************/

/*******************************************************************************
 * Included Files
 *******************************************************************************/

#include <nuttx/config.h>

#include <string.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/kmalloc.h>
#include <nuttx/usb/usbhost.h>
#include <nuttx/usb/usbhost_devaddr.h>

/*******************************************************************************
 * Pre-processor Definitions
 *******************************************************************************/

/*******************************************************************************
 * Private Functions
 *******************************************************************************/

/****************************************************************************
 * Name: usbhost_takesem and usbhost_givesem
 *
 * Description:
 *   This is just a wrapper to handle the annoying behavior of semaphore
 *   waits that return due to the receipt of a signal.
 *
 *******************************************************************************/

static void usbhost_takesem(FAR struct usbhost_devaddr_s *devgen)
{
  /* Take the semaphore (perhaps waiting) */

  while (sem_wait(&devgen->exclsem) != 0)
    {
      /* The only case that an error should occur here is if the wait was
       * awakened by a signal.
       */

      ASSERT(errno == EINTR);
    }
}

#define usbhost_givesem(devgen) sem_post(&devgen->exclsem)

/*******************************************************************************
 * Name: usbhost_devaddr_allocate
 *
 * Description:
 *   Allocate a new unique device address.
 *
 * Assumptions:
 *   Caller hold the exclsem
 *
 *******************************************************************************/

static int usbhost_devaddr_allocate(FAR struct usbhost_devaddr_s *devgen)
{
  uint8_t startaddr = devgen->next;
  uint8_t devaddr;
  int index;
  int bitno;

  /* Loop until we find a valid device address */

  for (;;)
    {
      /* Try the next device address */

      devaddr = devgen->next;
      if (devgen->next >= 0x7f)
        {
          devgen->next = 1;
        }
      else
        {
          devgen->next++;
        }

      /* Is this address already allocated? */

      index = devaddr >> 5;
      bitno = devaddr & 0x1f;
      if ((devgen->alloctab[index] & (1 << bitno)) == 0)
        {
          /* No... allocate it now */

          devgen->alloctab[index] |= (1 << bitno);
          return (int)devaddr;
        }

      /* This address has already been allocated.  The followign logic will
       * prevent (unexpected) infinite loops.
       */

      if (startaddr == devaddr)
        {
          /* We are back where we started... the are no free device address */

          return -ENOMEM;
        }
    }
}

/*******************************************************************************
 * Name: usbhost_devaddr_free
 *
 * Description:
 *   De-allocate a device address.
 *
 * Assumptions:
 *   Caller hold the exclsem
 *
 *******************************************************************************/

static void usbhost_devaddr_free(FAR struct usbhost_devaddr_s *devgen,
                                 uint8_t devaddr)
{
  int index;
  int bitno;

  /* Free the address by clearing the associated bit in the alloctab[]; */

  index = devaddr >> 5;
  bitno = devaddr & 0x1f;

  DEBUGASSERT((devgen->alloctab[index] |= (1 << bitno)) != 0);
  devgen->alloctab[index] &= ~(1 << bitno);

  /* Reset the next pointer if the one just released has a lower value */

  if (devaddr < devgen->next)
    {
      devgen->next = devaddr;
    }
}

/*******************************************************************************
 * Name: usbhost_roothubport
 *
 * Description:
 *   Find and return a reference the root hub port.
 *
 *******************************************************************************/

static inline FAR struct usbhost_roothubport_s *
usbhost_roothubport(FAR struct usbhost_hubport_s *hport)
{
#ifdef CONFIG_USBHOST_HUB
  /* If this is a root hub port then the parent port pointer will be NULL.
   * Otherwise, we need to traverse the parent pointer list until we find the
   * root hub port.
   */

  while (hport->parent != NULL)
    {
      /* This is not a root hub port.  It is a port on a hub.  Try the port of
       * the parent hub that supports this port.
       */

      hport = hport->parent;
    }
#endif

  return (FAR struct usbhost_roothubport_s *)hport;
}

/*******************************************************************************
 * Name: usbhost_devaddr_gen
 *
 * Description:
 *   Find root hub port and return a reference to the device function address
 *   data set.
 *
 *******************************************************************************/

static FAR struct usbhost_devaddr_s *
usbhost_devaddr_gen(FAR struct usbhost_hubport_s *hport)
{
  FAR struct usbhost_roothubport_s *rhport;

  rhport = usbhost_roothubport(hport);
  if (rhport != NULL)
    {
      return &rhport->devgen;
    }

  return NULL;
}

/*******************************************************************************
 * Public Functions
 *******************************************************************************/

/*******************************************************************************
 * Name: usbhost_devaddr_initialize
 *
 * Description:
 *   Initialize the caller provided struct usbhost_devaddr_s instance in
 *   preparation for the management of device addresses on behalf of an root
 *   hub port.
 *
 * Input Parameters:
 *   rhport - A reference to a roothubport structure.
 *
 * Returned Value:
 *   None
 *
 *******************************************************************************/

void usbhost_devaddr_initialize(FAR struct usbhost_roothubport_s *rhport)
{
  FAR struct usbhost_devaddr_s *devgen;

  DEBUGASSERT(rhport);
  devgen = &rhport->devgen;

  memset(devgen, 0, sizeof(struct usbhost_devaddr_s));
  sem_init(&devgen->exclsem, 0, 1);
  devgen->next = 1;
}

/*******************************************************************************
 * Name: usbhost_devaddr_create
 *
 * Description:
 *   Create a new unique device address for this hub port.
 *
 * Input Parameters:
 *   hport - A reference to a hub port structure to which a device has been
 *     newly connected and so is in need of a function address.
 *
 * Returned Value:
 *   On success, a new device function address in the the range 0x01 to 0x7f
 *   is returned.  On failure, a negated errno value is returned.
 *
 *******************************************************************************/

int usbhost_devaddr_create(FAR struct usbhost_hubport_s *hport)
{
  FAR struct usbhost_devaddr_s *devgen;
  int devaddr;

  /* Get the address generation data from the root hub port */

  DEBUGASSERT(hport);
  devgen = usbhost_devaddr_gen(hport);
  DEBUGASSERT(devgen);

  /* Get exclusive access to the root hub port device address data */

  usbhost_takesem(devgen);

  /* Allocate a device address */

  devaddr = usbhost_devaddr_allocate(devgen);
  usbhost_givesem(devgen);

  if (devaddr < 0)
    {
      udbg("ERROR: Failed to allocate a device address\n");
    }

  return devaddr;
}

/*******************************************************************************
 * Name: usbhost_devaddr_destroy
 *
 * Description:
 *   Release a device address previously assigned by usbhost_devaddr_create().
 *
 * Input Parameters:
 *   hport - A reference to a hub port structure from which a device has been
 *     disconnected and so no longer needs the function address.
 *   devaddr - The address to be released.
 *
 * Returned Value:
 *   None
 *
 *******************************************************************************/

void usbhost_devaddr_destroy(FAR struct usbhost_hubport_s *hport, uint8_t devaddr)
{
  FAR struct usbhost_devaddr_s *devgen;

  /* Ignore bad device address */

  if (devaddr > 0 && devaddr < 0x7f)
    {
      /* Get the address generation data from the root hub port */

      DEBUGASSERT(hport);
      devgen = usbhost_devaddr_gen(hport);
      DEBUGASSERT(devgen);

      /* Get exclusive access to the root hub port device address data */

      usbhost_takesem(devgen);

      /* Free the device address */

      usbhost_devaddr_free(devgen, devaddr);
      usbhost_givesem(devgen);
    }
}