src/dev/arm/a9scu.cc

   1 /*
   2  * Copyright (c) 2010 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Authors: Ali Saidi
  38  */
  39
  40 #include "base/intmath.hh"
  41 #include "base/trace.hh"
  42 #include "dev/arm/a9scu.hh"
  43 #include "mem/packet.hh"
  44 #include "mem/packet_access.hh"
  45 #include "sim/system.hh"
  46
  47 A9SCU::A9SCU(Params *p)
  48     : BasicPioDevice(p, 0x60)
  49 {
  50 }
  51
  52 Tick
  53 A9SCU::read(PacketPtr pkt)
  54 {
  55     assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize);
  56     assert(pkt->getSize() == 4);
  57     Addr daddr = pkt->getAddr() - pioAddr;
  58
  59     switch(daddr) {
  60       case Control:
  61         pkt->set(1); // SCU already enabled
  62         break;
  63       case Config:
  64         /* Without making a completely new SCU, we can use the core count field
  65          * as 4 bits and inform the OS of up to 16 CPUs.  Although the core
  66          * count is technically bits [1:0] only, bits [3:2] are SBZ for future
  67          * expansion like this.
  68          */
  69         if (sys->numContexts() > 4) {
  70             warn_once("A9SCU with >4 CPUs is unsupported\n");
  71             if (sys->numContexts() > 15)
  72                 fatal("Too many CPUs (%d) for A9SCU!\n", sys->numContexts());
  73         }
  74         int smp_bits, core_cnt;
  75         smp_bits = power(2,sys->numContexts()) - 1;
  76         core_cnt = sys->numContexts() - 1;
  77         pkt->set(smp_bits << 4 | core_cnt);
  78         break;
  79       default:
  80         // Only configuration register is implemented
  81         panic("Tried to read SCU at offset %#x\n", daddr);
  82         break;
  83     }
  84     pkt->makeAtomicResponse();
  85     return pioDelay;
  86
  87 }
  88
  89 Tick
  90 A9SCU::write(PacketPtr pkt)
  91 {
  92     assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize);
  93
  94     Addr daddr = pkt->getAddr() - pioAddr;
  95     switch (daddr) {
  96       default:
  97         // Nothing implemented at this point
  98         panic("Tried to write SCU at offset %#x\n", daddr);
  99         break;
 100     }
 101     pkt->makeAtomicResponse();
 102     return pioDelay;
 103 }
 104
 105 A9SCU *
 106 A9SCUParams::create()
 107 {
 108     return new A9SCU(this);
 109 }