pllnva3.c

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

#include "pll.h"

int
nva3_pll_calc(struct nouveau_clock *clock, 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);

    for (M = lM; M <= hM; M++) {
        u32 tmp = freq * *P * M;
        N  = tmp / info->refclk;
        fN = tmp % info->refclk;
        if (!pfN && fN >= info->refclk / 2)
            N++;

        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) - 4096) & 0xffff;
            return freq;
        }
    }

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

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