rtems/bsps/shared/grlib/amba/ambapp_freq.c

/* SPDX-License-Identifier: BSD-2-Clause */

/*
 *  AMBA Plug & Play routines
 *
 *  COPYRIGHT (c) 2011
 *  Aeroflex Gaisler
 *
 * 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.
 *
 * 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.
 */

#include <grlib/ambapp.h>

/* Calculate AHB Bus frequency of
 *   - Bus[0] (inverse=1), relative to the frequency of Bus[ahbidx]
 *     NOTE: set freq_hz to frequency of Bus[ahbidx].
 *   or
 *   - Bus[ahbidx] (inverse=0), relative to the frequency of Bus[0]
 *     NOTE: set freq_hz to frequency of Bus[0].
 *
 * If a unsupported bridge is found the invalid frequncy of 0Hz is
 * returned.
 */
static unsigned int ambapp_freq_calc(
  struct ambapp_bus *abus,
  int                ahbidx,
  unsigned int       freq_hz,
  int                inverse
)
{
  struct ambapp_ahb_info *ahb;
  struct ambapp_dev      *bridge;
  unsigned char           ffact;
  int                     dir;

  /* Found Bus0? */
  bridge = abus->ahbs[ ahbidx ].bridge;
  if ( !bridge ) {
    return freq_hz;
  }

  /* Find this bus frequency relative to freq_hz */
  if (
    ( bridge->vendor == VENDOR_GAISLER ) &&
    ( ( bridge->device == GAISLER_AHB2AHB ) ||
      ( bridge->device == GAISLER_L2CACHE ) )
  ) {
    ahb = DEV_TO_AHB( bridge );
    ffact = ( ahb->custom[ 0 ] & AMBAPP_FLAG_FFACT ) >> 4;
    if ( ffact != 0 ) {
      dir = ahb->custom[ 0 ] & AMBAPP_FLAG_FFACT_DIR;

      /* Calculate frequency by dividing or
       * multiplying system frequency
       */
      if ( ( dir && !inverse ) || ( !dir && inverse ) ) {
        freq_hz = freq_hz * ffact;
      } else {
        freq_hz = freq_hz / ffact;
      }
    }
    return ambapp_freq_calc( abus, ahb->common.ahbidx, freq_hz, inverse );
  } else {
    /* Unknown bridge, impossible to calc frequency */
    return 0;
  }
}

/* Find the frequency of all AHB Buses from knowing the frequency of one
 * particular APB/AHB Device.
 */
void ambapp_freq_init(
  struct ambapp_bus *abus,
  struct ambapp_dev *dev,
  unsigned int       freq_hz
)
{
  struct ambapp_common_info *info;
  int                        i;

  for ( i = 0; i < AHB_BUS_MAX; i++ ) {
    abus->ahbs[ i ].freq_hz = 0;
  }

  /* Register Frequency at the AHB bus that the device the user gave us
   * is located at.
   */
  if ( dev ) {
    info = DEV_TO_COMMON( dev );
    abus->ahbs[ info->ahbidx ].freq_hz = freq_hz;

    /* Find Frequency of Bus 0 */
    abus->ahbs[ 0 ].freq_hz = ambapp_freq_calc(
      abus,
      info->ahbidx,
      freq_hz,
      1
    );
  } else {
    abus->ahbs[ 0 ].freq_hz = freq_hz;
  }

  /* Find Frequency of all except for Bus0 and the bus which frequency
   * was reported at
   */
  for ( i = 1; i < AHB_BUS_MAX; i++ ) {
    if ( abus->ahbs[ i ].ioarea == 0 ) {
      break;
    }
    if ( abus->ahbs[ i ].freq_hz != 0 ) {
      continue;
    }
    abus->ahbs[ i ].freq_hz = ambapp_freq_calc(
      abus,
      i,
      abus->ahbs[ 0 ].freq_hz,
      0
    );
  }
}

/* Assign a AMBA Bus a frequency but reporting the frequency of a
 * particular AHB/APB device */
unsigned int ambapp_freq_get( struct ambapp_bus *abus, struct ambapp_dev *dev )
{
  struct ambapp_common_info *info = DEV_TO_COMMON( dev );
  return abus->ahbs[ info->ahbidx ].freq_hz;
}