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);
101