1/* 2 * linux/arch/arm/common/icst307.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 ICST307 11 * clock generators. See http://www.icst.com/ for more information 12 * on these devices. 13 * 14 * This is an almost identical implementation to the ICST525 clock generator. 15 * The s2div and idx2s files are different 16 */ 17#include <linux/module.h> 18#include <linux/kernel.h> 19 20#include <asm/hardware/icst.h> 21 22/* 23 * Divisors for each OD setting. 24 */ 25const unsigned char icst307_s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 }; 26const unsigned char icst525_s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 }; 27EXPORT_SYMBOL(icst307_s2div); 28EXPORT_SYMBOL(icst525_s2div); 29 30unsigned long icst_hz(const struct icst_params *p, struct icst_vco vco) 31{ 32 return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * p->s2div[vco.s]); 33} 34 35EXPORT_SYMBOL(icst_hz); 36 37/* 38 * Ascending divisor S values. 39 */ 40const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 }; 41const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 }; 42EXPORT_SYMBOL(icst307_idx2s); 43EXPORT_SYMBOL(icst525_idx2s); 44 45struct icst_vco 46icst_hz_to_vco(const struct icst_params *p, unsigned long freq) 47{ 48 struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max }; 49 unsigned long f; 50 unsigned int i = 0, rd, best = (unsigned int)-1; 51 52 /* 53 * First, find the PLL output divisor such 54 * that the PLL output is within spec. 55 */ 56 do { 57 f = freq * p->s2div[p->idx2s[i]]; 58 59 if (f > p->vco_min && f <= p->vco_max) 60 break; 61 } while (i < 8); 62 63 if (i >= 8) 64 return vco; 65 66 vco.s = p->idx2s[i]; 67 68 /* 69 * Now find the closest divisor combination 70 * which gives a PLL output of 'f'. 71 */ 72 for (rd = p->rd_min; rd <= p->rd_max; rd++) { 73 unsigned long fref_div, f_pll; 74 unsigned int vd; 75 int f_diff; 76 77 fref_div = (2 * p->ref) / rd; 78 79 vd = (f + fref_div / 2) / fref_div; 80 if (vd < p->vd_min || vd > p->vd_max) 81 continue; 82 83 f_pll = fref_div * vd; 84 f_diff = f_pll - f; 85 if (f_diff < 0) 86 f_diff = -f_diff; 87 88 if ((unsigned)f_diff < best) { 89 vco.v = vd - 8; 90 vco.r = rd - 2; 91 if (f_diff == 0) 92 break; 93 best = f_diff; 94 } 95 } 96 97 return vco; 98} 99 100EXPORT_SYMBOL(icst_hz_to_vco); 101