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
  29 int
  30 gt215_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 }