/*
 * Copyright 2010 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Ben Skeggs
 */
#include "pll.h"

#include <subdev/bios.h>
#include <subdev/bios/pll.h>

int
gt215_pll_calc(struct nvkm_subdev *subdev, struct nvbios_pll *info,
               u32 freq, int *pN, int *pfN, int *pM, int *P)
{
        u32 best_err = ~0, err;
        int M, lM, hM, N, fN;

        *P = info->vco1.max_freq / freq;
        if (*P > info->max_p)
                *P = info->max_p;
        if (*P < info->min_p)
                *P = info->min_p;

        lM = (info->refclk + info->vco1.max_inputfreq) / info->vco1.max_inputfreq;
        lM = max(lM, (int)info->vco1.min_m);
        hM = (info->refclk + info->vco1.min_inputfreq) / info->vco1.min_inputfreq;
        hM = min(hM, (int)info->vco1.max_m);
        lM = min(lM, hM);

        for (M = lM; M <= hM; M++) {
                u32 tmp = freq * *P * M;
                N  = tmp / info->refclk;
                fN = tmp % info->refclk;

                if (!pfN) {
                        if (fN >= info->refclk / 2)
                                N++;
                } else {
                        if (fN <  info->refclk / 2)
                                N--;
                        fN = tmp - (N * info->refclk);
                }

                if (N < info->vco1.min_n)
                        continue;
                if (N > info->vco1.max_n)
                        break;

                err = abs(freq - (info->refclk * N / M / *P));
                if (err < best_err) {
                        best_err = err;
                        *pN = N;
                        *pM = M;
                }

                if (pfN) {
                        *pfN = ((fN << 13) + info->refclk / 2) / info->refclk;
                        *pfN = (*pfN - 4096) & 0xffff;
                        return freq;
                }
        }

        if (unlikely(best_err == ~0)) {
                nvkm_error(subdev, "unable to find matching pll values\n");
                return -EINVAL;
        }

        return info->refclk * *pN / *pM / *P;
}