/*
   * (C) Copyright 2003 Intracom S.A.
   * Pantelis Antoniou <panto@intracom.gr>
   *
   * This little program makes an exhaustive search for the
   * correct terms of pdf, mfi, mfn, mfd, s, dbrmo, in PLPRCR.
   * The goal is to produce a gclk2 from a xin input, while respecting
   * all the restrictions on their combination.
   *
   * Generaly you select the first row of the produced table.
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  
  #include <stdio.h>
  #include <stdlib.h>
  
  #define DPREF_MIN	 10000000
  #define DPREF_MAX	 32000000
  
  #define DPGDCK_MAX	320000000
  #define DPGDCK_MIN	160000000
  
  #define S_MIN		0
  #define S_MAX		2
  
  #define MFI_MIN		5
  #define MFI_MAX		15
  
  #define MFN_MIN		0
  #define MFN_MAX		15
  
  #define MFD_MIN		0
  #define MFD_MAX		31
  
  #define MF_MIN		5
  #define MF_MAX		15
  
  #define PDF_MIN		0
  #define PDF_MAX		15
  
  #define GCLK2_MAX	150000000
  
  static int calculate (int xin, int target_clock,
  		      int ppm, int pdf, int mfi, int mfn, int mfd, int s,
  		      int *dprefp, int *dpgdckp, int *jdbckp,
  		      int *gclk2p, int *dbrmop)
  {
  	unsigned int dpref, dpgdck, jdbck, gclk2, t1, t2, dbrmo;
  
  	/* valid MFI? */
  	if (mfi < MFI_MIN)
  		return -1;
  
  	/* valid num, denum? */
  	if (mfn > 0 && mfn >= mfd)
  		return -1;
  
  	dpref = xin / (pdf + 1);
  
  	/* valid dpef? */
  	if (dpref < DPREF_MIN || dpref > DPREF_MAX)
  		return -1;
  
  	if (mfn == 0) {
  		dpgdck  = (2 * mfi * xin) / (pdf + 1) ;
  		dbrmo = 0;
  	} else {
  		/* 5 <= mfi + (mfn / mfd + 1) <= 15 */
  		t1 = mfd + 1;
  		t2 = mfi * t1 + mfn;
  		if ( MF_MIN * t1 > t2 || MF_MAX * t1 < t2)
  			return -1;
  
  		dpgdck  = (unsigned int)(2 * (mfi * mfd + mfi + mfn) *
  				(unsigned int)xin) /
  				((mfd + 1) * (pdf + 1));
  
  		dbrmo = 10 * mfn < (mfd + 1);
  	}
  
  	/* valid dpgclk? */
  	if (dpgdck < DPGDCK_MIN || dpgdck > DPGDCK_MAX)
  		return -1;
  
  	jdbck = dpgdck >> s;
  	gclk2 = jdbck / 2;
  
  	/* valid gclk2 */
  	if (gclk2 > GCLK2_MAX)
  		return -1;
  
  	t1 = abs(gclk2 - target_clock);
  
  	/* XXX max 1MHz dev. in clock */
  	if (t1 > 1000000)
  		return -1;
  
  	/* dev within range (XXX gclk2 scaled to avoid overflow) */
  	if (t1 * 1000 > (unsigned int)ppm * (gclk2 / 1000))
  		return -1;
  
  	*dprefp = dpref;
  	*dpgdckp = dpgdck;
  	*jdbckp = jdbck;
  	*gclk2p = gclk2;
  	*dbrmop = dbrmo;
  
  	return gclk2;
  }
  
  int conf_clock(int xin, int target_clock, int ppm)
  {
  	int pdf, s, mfn, mfd, mfi;
  	int dpref, dpgdck, jdbck, gclk2, xout, dbrmo;
  	int found = 0;
  
  	/* integer multipliers */
  	for (pdf = PDF_MIN; pdf <= PDF_MAX; pdf++) {
  		for (mfi = MFI_MIN; mfi <= MFI_MAX; mfi++) {
  			for (s = 0; s <= S_MAX; s++) {
  				xout = calculate(xin, target_clock,
  						 ppm, pdf, mfi, 0, 0, s,
  						 &dpref, &dpgdck, &jdbck,
  						 &gclk2, &dbrmo);
  				if (xout < 0)
  					continue;
  
  				if (found == 0) {
  					printf("pdf mfi mfn mfd s dbrmo     dpref    dpgdck     jdbck     gclk2 exact?
  ");
  					printf("--- --- --- --- - -----     -----    ------     -----     ----- ------
  ");
  				}
  
  				printf("%3d %3d --- --- %1d %5d %9d %9d %9d %9d%s
  ",
  					pdf, mfi, s, dbrmo,
  					dpref, dpgdck, jdbck, gclk2,
  					gclk2 == target_clock ? "    YES" : "");
  
  				found++;
  			}
  		}
  	}
  
  	/* fractional multipliers */
  	for (pdf = PDF_MIN; pdf <= PDF_MAX; pdf++) {
  		for (mfi = MFI_MIN; mfi <= MFI_MAX; mfi++) {
  			for (mfn = 1; mfn <= MFN_MAX; mfn++) {
  				for (mfd = 1; mfd <= MFD_MAX; mfd++) {
  					for (s = 0; s <= S_MAX; s++) {
  						xout = calculate(xin, target_clock,
  							    ppm, pdf, mfi, mfn, mfd, s,
  							    &dpref, &dpgdck, &jdbck,
  							    &gclk2, &dbrmo);
  						if (xout < 0)
  							continue;
  
  						if (found == 0) {
  							printf("pdf mfi mfn mfd s dbrmo     dpref    dpgdck     jdbck     gclk2 exact?
  ");
  							printf("--- --- --- --- - -----     -----    ------     -----     ----- ------
  ");
  						}
  
  						printf("%3d %3d %3d %3d %1d %5d %9d %9d %9d %9d%s
  ",
  							pdf, mfi, mfn, mfd, s,
  							dbrmo, dpref, dpgdck, jdbck, gclk2,
  							gclk2 == target_clock ? "    YES" : "");
  
  						found++;
  					}
  				}
  			}
  
  		}
  	}
  
  	return found;
  }
  
  int main(int argc, char *argv[])
  {
  	int xin, want_gclk2, found, ppm = 100;
  
  	if (argc < 3) {
  		fprintf(stderr, "usage: mpc86x_clk <xin> <want_gclk2> [ppm]
  ");
  		fprintf(stderr, "       default ppm is 100
  ");
  		return 10;
  	}
  
  	xin  = atoi(argv[1]);
  	want_gclk2 = atoi(argv[2]);
  	if (argc >= 4)
  		ppm = atoi(argv[3]);
  
  	found = conf_clock(xin, want_gclk2, ppm);
  	if (found <= 0) {
  		fprintf(stderr, "cannot produce gclk2 %d from xin %d
  ",
  			want_gclk2, xin);
  		return EXIT_FAILURE;
  	}
  
  	return EXIT_SUCCESS;
  }