LXR linux/drivers/gpu/drm/nouveau/nvkm/subdev/clk/pllgt215.c

   1/*
   2 * Copyright 2010 Red Hat Inc.
   3 *
   4 * Permission is hereby granted, free of charge, to any person obtaining a
   5 * copy of this software and associated documentation files (the "Software"),
   6 * to deal in the Software without restriction, including without limitation
   7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8 * and/or sell copies of the Software, and to permit persons to whom the
   9 * Software is furnished to do so, subject to the following conditions:
  10 *
  11 * The above copyright notice and this permission notice shall be included in
  12 * all copies or substantial portions of the Software.
  13 *
  14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20 * OTHER DEALINGS IN THE SOFTWARE.
  21 *
  22 * Authors: Ben Skeggs
  23 */
  24#include "pll.h"
  25
  26#include <subdev/bios.h>
  27#include <subdev/bios/pll.h>
  28
  29int
  30gt215_pll_calc(struct nvkm_subdev *subdev, struct nvbios_pll *info,
  31               u32 freq, int *pN, int *pfN, int *pM, int *P)
  32{
  33        u32 best_err = ~0, err;
  34        int M, lM, hM, N, fN;
  35
  36        *P = info->vco1.max_freq / freq;
  37        if (*P > info->max_p)
  38                *P = info->max_p;
  39        if (*P < info->min_p)
  40                *P = info->min_p;
  41
  42        lM = (info->refclk + info->vco1.max_inputfreq) / info->vco1.max_inputfreq;
  43        lM = max(lM, (int)info->vco1.min_m);
  44        hM = (info->refclk + info->vco1.min_inputfreq) / info->vco1.min_inputfreq;
  45        hM = min(hM, (int)info->vco1.max_m);
  46        lM = min(lM, hM);
  47
  48        for (M = lM; M <= hM; M++) {
  49                u32 tmp = freq * *P * M;
  50                N  = tmp / info->refclk;
  51                fN = tmp % info->refclk;
  52
  53                if (!pfN) {
  54                        if (fN >= info->refclk / 2)
  55                                N++;
  56                } else {
  57                        if (fN <  info->refclk / 2)
  58                                N--;
  59                        fN = tmp - (N * info->refclk);
  60                }
  61
  62                if (N < info->vco1.min_n)
  63                        continue;
  64                if (N > info->vco1.max_n)
  65                        break;
  66
  67                err = abs(freq - (info->refclk * N / M / *P));
  68                if (err < best_err) {
  69                        best_err = err;
  70                        *pN = N;
  71                        *pM = M;
  72                }
  73
  74                if (pfN) {
  75                        *pfN = ((fN << 13) + info->refclk / 2) / info->refclk;
  76                        *pfN = (*pfN - 4096) & 0xffff;
  77                        return freq;
  78                }
  79        }
  80
  81        if (unlikely(best_err == ~0)) {
  82                nvkm_error(subdev, "unable to find matching pll values\n");
  83                return -EINVAL;
  84        }
  85
  86        return info->refclk * *pN / *pM / *P;
  87}
  88