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.idt.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);