1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/arch/arm/common/icst307.c
5 * Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved.
7 * Support functions for calculating clocks/divisors for the ICST307
8 * clock generators. See http://www.idt.com/ for more information
11 * This is an almost identical implementation to the ICST525 clock generator.
12 * The s2div and idx2s files are different
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <asm/div64.h>
20 * Divisors for each OD setting.
22 const unsigned char icst307_s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 };
23 const unsigned char icst525_s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
24 EXPORT_SYMBOL(icst307_s2div);
25 EXPORT_SYMBOL(icst525_s2div);
27 unsigned long icst_hz(const struct icst_params *p, struct icst_vco vco)
29 u64 dividend = p->ref * 2 * (u64)(vco.v + 8);
30 u32 divisor = (vco.r + 2) * p->s2div[vco.s];
32 do_div(dividend, divisor);
33 return (unsigned long)dividend;
36 EXPORT_SYMBOL(icst_hz);
39 * Ascending divisor S values.
41 const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 };
42 const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 };
43 EXPORT_SYMBOL(icst307_idx2s);
44 EXPORT_SYMBOL(icst525_idx2s);
47 icst_hz_to_vco(const struct icst_params *p, unsigned long freq)
49 struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
51 unsigned int i = 0, rd, best = (unsigned int)-1;
54 * First, find the PLL output divisor such
55 * that the PLL output is within spec.
58 f = freq * p->s2div[p->idx2s[i]];
60 if (f > p->vco_min && f <= p->vco_max)
71 * Now find the closest divisor combination
72 * which gives a PLL output of 'f'.
74 for (rd = p->rd_min; rd <= p->rd_max; rd++) {
75 unsigned long fref_div, f_pll;
79 fref_div = (2 * p->ref) / rd;
81 vd = (f + fref_div / 2) / fref_div;
82 if (vd < p->vd_min || vd > p->vd_max)
85 f_pll = fref_div * vd;
90 if ((unsigned)f_diff < best) {
102 EXPORT_SYMBOL(icst_hz_to_vco);