drivers/gpu/drm/nouveau/nv50_calc.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
  25 #include "drmP.h"
  26 #include "drm_fixed.h"
  27 #include "nouveau_drv.h"
  28 #include "nouveau_hw.h"
  29
  30 int
  31 nv50_calc_pll(struct drm_device *dev, struct pll_lims *pll, int clk,
  32               int *N1, int *M1, int *N2, int *M2, int *P)
  33 {
  34         struct nouveau_pll_vals pll_vals;
  35         int ret;
  36
  37         ret = nouveau_calc_pll_mnp(dev, pll, clk, &pll_vals);
  38         if (ret <= 0)
  39                 return ret;
  40
  41         *N1 = pll_vals.N1;
  42         *M1 = pll_vals.M1;
  43         *N2 = pll_vals.N2;
  44         *M2 = pll_vals.M2;
  45         *P = pll_vals.log2P;
  46         return ret;
  47 }
  48
  49 int
  50 nv50_calc_pll2(struct drm_device *dev, struct pll_lims *pll, int clk,
  51                int *N, int *fN, int *M, int *P)
  52 {
  53         fixed20_12 fb_div, a, b;
  54         u32 refclk = pll->refclk / 10;
  55         u32 max_vco_freq = pll->vco1.maxfreq / 10;
  56         u32 max_vco_inputfreq = pll->vco1.max_inputfreq / 10;
  57         clk /= 10;
  58
  59         *P = max_vco_freq / clk;
  60         if (*P > pll->max_p)
  61                 *P = pll->max_p;
  62         if (*P < pll->min_p)
  63                 *P = pll->min_p;
  64
  65         /* *M = floor((refclk + max_vco_inputfreq) / max_vco_inputfreq); */
  66         a.full = dfixed_const(refclk + max_vco_inputfreq);
  67         b.full = dfixed_const(max_vco_inputfreq);
  68         a.full = dfixed_div(a, b);
  69         a.full = dfixed_floor(a);
  70         *M = dfixed_trunc(a);
  71
  72         /* fb_div = (vco * *M) / refclk; */
  73         fb_div.full = dfixed_const(clk * *P);
  74         fb_div.full = dfixed_mul(fb_div, a);
  75         a.full = dfixed_const(refclk);
  76         fb_div.full = dfixed_div(fb_div, a);
  77
  78         /* *N = floor(fb_div); */
  79         a.full = dfixed_floor(fb_div);
  80         *N = dfixed_trunc(fb_div);
  81
  82         /* *fN = (fmod(fb_div, 1.0) * 8192) - 4096; */
  83         b.full = dfixed_const(8192);
  84         a.full = dfixed_mul(a, b);
  85         fb_div.full = dfixed_mul(fb_div, b);
  86         fb_div.full = fb_div.full - a.full;
  87         *fN = dfixed_trunc(fb_div) - 4096;
  88         *fN &= 0xffff;
  89
  90         return clk;
  91 }