arch/arm/common/icst525.c

   1 /*
   2  *  linux/arch/arm/common/icst525.c
   3  *
   4  *  Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  Support functions for calculating clocks/divisors for the ICST525
  11  *  clock generators.  See http://www.icst.com/ for more information
  12  *  on these devices.
  13  */
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16
  17 #include <asm/hardware/icst525.h>
  18
  19 /*
  20  * Divisors for each OD setting.
  21  */
  22 static unsigned char s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
  23
  24 unsigned long icst525_khz(const struct icst525_params *p, struct icst525_vco vco)
  25 {
  26         return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * s2div[vco.s]);
  27 }
  28
  29 EXPORT_SYMBOL(icst525_khz);
  30
  31 /*
  32  * Ascending divisor S values.
  33  */
  34 static unsigned char idx2s[] = { 1, 3, 4, 7, 5, 2, 6, 0 };
  35
  36 struct icst525_vco
  37 icst525_khz_to_vco(const struct icst525_params *p, unsigned long freq)
  38 {
  39         struct icst525_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
  40         unsigned long f;
  41         unsigned int i = 0, rd, best = (unsigned int)-1;
  42
  43         /*
  44          * First, find the PLL output divisor such
  45          * that the PLL output is within spec.
  46          */
  47         do {
  48                 f = freq * s2div[idx2s[i]];
  49
  50                 /*
  51                  * f must be between 10MHz and
  52                  *  320MHz (5V) or 200MHz (3V)
  53                  */
  54                 if (f > 10000 && f <= p->vco_max)
  55                         break;
  56         } while (i < ARRAY_SIZE(idx2s));
  57
  58         if (i >= ARRAY_SIZE(idx2s))
  59                 return vco;
  60
  61         vco.s = idx2s[i];
  62
  63         /*
  64          * Now find the closest divisor combination
  65          * which gives a PLL output of 'f'.
  66          */
  67         for (rd = p->rd_min; rd <= p->rd_max; rd++) {
  68                 unsigned long fref_div, f_pll;
  69                 unsigned int vd;
  70                 int f_diff;
  71
  72                 fref_div = (2 * p->ref) / rd;
  73
  74                 vd = (f + fref_div / 2) / fref_div;
  75                 if (vd < p->vd_min || vd > p->vd_max)
  76                         continue;
  77
  78                 f_pll = fref_div * vd;
  79                 f_diff = f_pll - f;
  80                 if (f_diff < 0)
  81                         f_diff = -f_diff;
  82
  83                 if ((unsigned)f_diff < best) {
  84                         vco.v = vd - 8;
  85                         vco.r = rd - 2;
  86                         if (f_diff == 0)
  87                                 break;
  88                         best = f_diff;
  89                 }
  90         }
  91
  92         return vco;
  93 }
  94
  95 EXPORT_SYMBOL(icst525_khz_to_vco);
  96
  97 struct icst525_vco
  98 icst525_ps_to_vco(const struct icst525_params *p, unsigned long period)
  99 {
 100         struct icst525_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
 101         unsigned long f, ps;
 102         unsigned int i = 0, rd, best = (unsigned int)-1;
 103
 104         ps = 1000000000UL / p->vco_max;
 105
 106         /*
 107          * First, find the PLL output divisor such
 108          * that the PLL output is within spec.
 109          */
 110         do {
 111                 f = period / s2div[idx2s[i]];
 112
 113                 /*
 114                  * f must be between 10MHz and
 115                  *  320MHz (5V) or 200MHz (3V)
 116                  */
 117                 if (f >= ps && f < 100000)
 118                         break;
 119         } while (i < ARRAY_SIZE(idx2s));
 120
 121         if (i >= ARRAY_SIZE(idx2s))
 122                 return vco;
 123
 124         vco.s = idx2s[i];
 125
 126         ps = 500000000UL / p->ref;
 127
 128         /*
 129          * Now find the closest divisor combination
 130          * which gives a PLL output of 'f'.
 131          */
 132         for (rd = p->rd_min; rd <= p->rd_max; rd++) {
 133                 unsigned long f_in_div, f_pll;
 134                 unsigned int vd;
 135                 int f_diff;
 136
 137                 f_in_div = ps * rd;
 138
 139                 vd = (f_in_div + f / 2) / f;
 140                 if (vd < p->vd_min || vd > p->vd_max)
 141                         continue;
 142
 143                 f_pll = (f_in_div + vd / 2) / vd;
 144                 f_diff = f_pll - f;
 145                 if (f_diff < 0)
 146                         f_diff = -f_diff;
 147
 148                 if ((unsigned)f_diff < best) {
 149                         vco.v = vd - 8;
 150                         vco.r = rd - 2;
 151                         if (f_diff == 0)
 152                                 break;
 153                         best = f_diff;
 154                 }
 155         }
 156
 157         return vco;
 158 }
 159
 160 EXPORT_SYMBOL(icst525_ps_to_vco);