2 * linux/arch/arm/common/icst525.c
4 * Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved.
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.
10 * Support functions for calculating clocks/divisors for the ICST525
11 * clock generators. See http://www.icst.com/ for more information
14 #include <linux/module.h>
15 #include <linux/kernel.h>
17 #include <asm/hardware/icst525.h>
20 * Divisors for each OD setting.
22 static unsigned char s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
24 unsigned long icst525_hz(const struct icst_params *p, struct icst_vco vco)
26 return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * s2div[vco.s]);
29 EXPORT_SYMBOL(icst525_hz);
32 * Ascending divisor S values.
34 static unsigned char idx2s[] = { 1, 3, 4, 7, 5, 2, 6, 0 };
37 icst525_hz_to_vco(const struct icst_params *p, unsigned long freq)
39 struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
41 unsigned int i = 0, rd, best = (unsigned int)-1;
44 * First, find the PLL output divisor such
45 * that the PLL output is within spec.
48 f = freq * s2div[idx2s[i]];
51 * f must be between 10MHz and
52 * 320MHz (5V) or 200MHz (3V)
54 if (f > p->vco_min && f <= p->vco_max)
56 } while (i < ARRAY_SIZE(idx2s));
58 if (i >= ARRAY_SIZE(idx2s))
64 * Now find the closest divisor combination
65 * which gives a PLL output of 'f'.
67 for (rd = p->rd_min; rd <= p->rd_max; rd++) {
68 unsigned long fref_div, f_pll;
72 fref_div = (2 * p->ref) / rd;
74 vd = (f + fref_div / 2) / fref_div;
75 if (vd < p->vd_min || vd > p->vd_max)
78 f_pll = fref_div * vd;
83 if ((unsigned)f_diff < best) {
95 EXPORT_SYMBOL(icst525_hz_to_vco);