fpga_puf_neorv32_cfs.c

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// # fpga_puf - https:/stnolting/fpga_puf                          (c) Stephan Nolting #
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#include <neorv32.h>
#include "fpga_puf_neorv32_cfs.h"


/**********************************************************************//**
 * Check if PUF CFS unit was synthesized.
 *
 * @return 0 if PUF CFS was not synthesized, 1 if PUF CFS is available.
 **************************************************************************/
int fpga_puf_available(void) {

  if (NEORV32_SYSINFO.SOC & (1 << SYSINFO_SOC_IO_CFS)) {
    return 1;
  }
  else {
    return 0;
  }
}


/**********************************************************************//**
 * Get 96-bit PUF ID raw (!) data.
 *
 * @warning This function returns the RAW PUF ID. Since some bits might be very noisy
 * an additional post-processing is required to ensure an ID that is reliable
 * (static over time and operating conditions).
 *
 * @param[in,out] puf_data 3x 32-bit array for the 96-bit raw ID (#puf_data_t);
 **************************************************************************/
void fpga_puf_get_raw(puf_data_t *puf_data) {

  FPGA_PUF_CTRL = 0; // reset

  // enable PUF and trigger sampling
  FPGA_PUF_CTRL = (1<<PUF_CTRL_SAMPLE) | (1<<PUF_CTRL_EN);

  // wait for sampling to complete, takes about ~102 clock cycles (deterministic)
  while(FPGA_PUF_CTRL & (1<<PUF_CTRL_SAMPLE));

  FPGA_PUF_CTRL = 0; // shutdown

  // get 96-bit PUF ID
  puf_data->id[0] = FPGA_PUF_ID0;
  puf_data->id[1] = FPGA_PUF_ID1;
  puf_data->id[2] = FPGA_PUF_ID2;
}