src/boot/setup.c


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#include "../utils/uart.h"
#include "../utils/io.h"
#include "../demo/demo_functionality.h"
#include "../memory/paging.h"
#include "../atags/atags.h"
// for POWER_OF_2() macro... perhaps the macro should be moved
#include "../memory/memory.h"
#include "../clock/armclock.h"
#include "../scheduler.h"

void setup(uint32_t r0, uint32_t machine_type,
	   struct atag_header *atags)
{
  uart_init();
  
  // When we attach screen session after loading kernel with socat
  // we miss kernel's greeting... So we'll make the kernel wait for
  // one char we're going to send from within screen
  getchar();
  
  puts("Hello, kernel World!");

  prints("ARM machine type: 0x"); printhext(machine_type); puts("");

  uint32_t memory_size = 0;
  
  // value 3 introduced by stage1 code means no atags was found
  if (r0 == 3)
    {
      puts ("No ATAGS was found!");
    }
  else
    {
      prints("ATAGS copied to 0x");
      printhex((uint32_t) atags); puts("");

      puts("__ ATAGS contents __");

      print_atags(atags);

      puts("__ end of ATAGS contents __");

      memory_size = find_memory_size(atags);
    }
    
  if (memory_size)
    {
     char *unit;
     uint32_t size_in_unit;
     
     if (memory_size % POWER_OF_2(10))
      {
       unit = "B";
       size_in_unit = memory_size;
      }
     else if (memory_size % POWER_OF_2(20))
      {
       unit = "KB";
       size_in_unit = memory_size / POWER_OF_2(10);
      }
     else if (memory_size % POWER_OF_2(30))
      {
       unit = "MB";
       size_in_unit = memory_size / POWER_OF_2(20);
      }
     else
      {
       unit = "GB";
       size_in_unit = memory_size / POWER_OF_2(30);
      }
     
     prints ("memory available: ");
     printdect (size_in_unit);
     puts (unit);
    }
  else
    {
      // Most Pis have more, but qemu might give us little
      puts("Couldn't determine available memory - assuming 192MB");
      memory_size = 192 * POWER_OF_2(20);
    }

  // assume we need at least one section for PL0
  if (memory_size < PRIVILEGED_MEMORY_END + SECTION_SIZE)
    {
      puts("Not enough memory to continue");
      while (1);
    }
  
  // prints some info
  demo_paging_support();

  // prints some info
  demo_current_mode();

  setup_pager_structures(memory_size);
  
  // prints some info and sets upp translation table, turns on MMU
  setup_flat_map();

  puts("Initializing clock");
  // sets some general settings for arm timer
  armclk_init();

  puts("Setting up scheduler's internal structures");
  setup_scheduler_structures();

  puts("Switching uart to use irqs");

  // note, that kernel's puts() is still going to use blocking io
  uart_irq_enable();
  
  // prints some info and sets up a section for PL0 code, loads a blob
  // there, then runs scheduler... never, ever, ever returns
  demo_setup_PL0();
}