text: /*
  Copyright (c) 2012, Broadcom Europe Ltd.
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
      * 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.
      * Neither the name of the copyright holder 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 HOLDER 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.
  
  Original:
  https://github.com/raspberrypi/userland/blob/master/host_applications/linux/apps/hello_pi/hello_fft/mailbox.c
  */
  
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  #include <fcntl.h>
  #include <unistd.h>
  #include <assert.h>
  #include <stdint.h>
  #include <sys/mman.h>
  #include <sys/ioctl.h>
  
  #include "mailbox.h"
  
  #define PAGE_SIZE (4*1024)
  
  void *mapmem(unsigned base, unsigned size)
  {
     int mem_fd;
     unsigned offset = base % PAGE_SIZE;
     base = base - offset;
     size = size + offset;
     /* open /dev/mem */
     if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
        printf("can't open /dev/mem\nThis program should be run as root. Try prefixing command with: sudo\n");
        exit (-1);
     }
     void *mem = mmap(
        0,
        size,
        PROT_READ|PROT_WRITE,
        MAP_SHARED/*|MAP_FIXED*/,
        mem_fd,
        base);
  #ifdef DEBUG
     printf("base=0x%x, mem=%p\n", base, mem);
  #endif
     if (mem == MAP_FAILED) {
        printf("mmap error %d\n", (int)mem);
        exit (-1);
     }
     close(mem_fd);
     return (char *)mem + offset;
  }
  
  void unmapmem(void *addr, unsigned size)
  {
     const intptr_t offset = (intptr_t)addr % PAGE_SIZE;
     addr = (char *)addr - offset;
     size = size + offset;
     int s = munmap(addr, size);
     if (s != 0) {
        printf("munmap error %d\n", s);
        exit (-1);
     }
  }
  
  /*
   * use ioctl to send mbox property message
   */
  
  static int mbox_property(int file_desc, void *buf)
  {
     int ret_val = ioctl(file_desc, IOCTL_MBOX_PROPERTY, buf);
  
     if (ret_val < 0) {
        printf("ioctl_set_msg failed:%d\n", ret_val);
     }
  
  #ifdef DEBUG
     unsigned *p = buf; int i; unsigned size = *(unsigned *)buf;
     for (i=0; i<size/4; i++)
        printf("%04x: 0x%08x\n", i*sizeof *p, p[i]);
  #endif
     return ret_val;
  }
  
  unsigned mem_alloc(int file_desc, unsigned size, unsigned align, unsigned flags)
  {
     int i=0;
     unsigned p[32];
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
  
     p[i++] = 0x3000c; // (the tag id)
     p[i++] = 12; // (size of the buffer)
     p[i++] = 12; // (size of the data)
     p[i++] = size; // (num bytes? or pages?)
     p[i++] = align; // (alignment)
     p[i++] = flags; // (MEM_FLAG_L1_NONALLOCATING)
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  unsigned mem_free(int file_desc, unsigned handle)
  {
     int i=0;
     unsigned p[32];
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
  
     p[i++] = 0x3000f; // (the tag id)
     p[i++] = 4; // (size of the buffer)
     p[i++] = 4; // (size of the data)
     p[i++] = handle;
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  unsigned mem_lock(int file_desc, unsigned handle)
  {
     int i=0;
     unsigned p[32];
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
  
     p[i++] = 0x3000d; // (the tag id)
     p[i++] = 4; // (size of the buffer)
     p[i++] = 4; // (size of the data)
     p[i++] = handle;
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  unsigned mem_unlock(int file_desc, unsigned handle)
  {
     int i=0;
     unsigned p[32];
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
  
     p[i++] = 0x3000e; // (the tag id)
     p[i++] = 4; // (size of the buffer)
     p[i++] = 4; // (size of the data)
     p[i++] = handle;
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  unsigned execute_code(int file_desc, unsigned code, unsigned r0, unsigned r1, unsigned r2, unsigned r3, unsigned r4, unsigned r5)
  {
     int i=0;
     unsigned p[32];
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
  
     p[i++] = 0x30010; // (the tag id)
     p[i++] = 28; // (size of the buffer)
     p[i++] = 28; // (size of the data)
     p[i++] = code;
     p[i++] = r0;
     p[i++] = r1;
     p[i++] = r2;
     p[i++] = r3;
     p[i++] = r4;
     p[i++] = r5;
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  unsigned qpu_enable(int file_desc, unsigned enable)
  {
     int i=0;
     unsigned p[32];
  
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
  
     p[i++] = 0x30012; // (the tag id)
     p[i++] = 4; // (size of the buffer)
     p[i++] = 4; // (size of the data)
     p[i++] = enable;
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  unsigned execute_qpu(int file_desc, unsigned num_qpus, unsigned control, unsigned noflush, unsigned timeout) {
     int i=0;
     unsigned p[32];
  
     p[i++] = 0; // size
     p[i++] = 0x00000000; // process request
     p[i++] = 0x30011; // (the tag id)
     p[i++] = 16; // (size of the buffer)
     p[i++] = 16; // (size of the data)
     p[i++] = num_qpus;
     p[i++] = control;
     p[i++] = noflush;
     p[i++] = timeout; // ms
  
     p[i++] = 0x00000000; // end tag
     p[0] = i*sizeof *p; // actual size
  
     mbox_property(file_desc, p);
     return p[5];
  }
  
  int mbox_open() {
     int file_desc;
  
     // open a char device file used for communicating with kernel mbox driver
     file_desc = open(DEVICE_FILE_NAME, 0);
     if (file_desc < 0) {
        printf("Can't open device file: %s\n", DEVICE_FILE_NAME);
        printf("Try creating a device file with: sudo mknod %s c %d 0\n", DEVICE_FILE_NAME, MAJOR_NUM);
        exit(-1);
     }
     return file_desc;
  }
  
  void mbox_close(int file_desc) {
    close(file_desc);
  }
  