/*
References:
  https://wiki.osdev.org/Detecting_Raspberry_Pi_Board
*/
#include <raspi.h>

#include <stdint.h>

int raspi_init() {
  int raspi;
  uint32_t reg;

  // Read the system register.
#if __aarch64__
  asm volatile ("mrs %x0, midr_el1" : "=r" (reg));
#else
  asm volatile ("mrc p15,0,%0,c0,c0,0" : "=r" (reg));
#endif

  // Get the PartNum and detect the board.
  switch ((reg >> 4) & 0xFFF) {
      case 0xB76: raspi = 1; break;
      case 0xC07: raspi = 2; break;
      case 0xD03: raspi = 3; break;
      case 0xD08: raspi = 4; break;
      default:    raspi = 0; break;
  }
  
  return raspi;
}