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#include <asm/div64.h>
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	u64 dividend = p->ref * 2 * (u64)(vco.v + 8);
33	u32 divisor = (vco.r + 2) * p->s2div[vco.s];
34
35	do_div(dividend, divisor);
36	return (unsigned long)dividend;
37}
38
39EXPORT_SYMBOL(icst_hz);
40
41/*
42 * Ascending divisor S values.
43 */
44const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 };
45const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 };
46EXPORT_SYMBOL(icst307_idx2s);
47EXPORT_SYMBOL(icst525_idx2s);
48
49struct icst_vco
50icst_hz_to_vco(const struct icst_params *p, unsigned long freq)
51{
52	struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
53	unsigned long f;
54	unsigned int i = 0, rd, best = (unsigned int)-1;
55
56	/*
57	 * First, find the PLL output divisor such
58	 * that the PLL output is within spec.
59	 */
60	do {
61		f = freq * p->s2div[p->idx2s[i]];
62
63		if (f > p->vco_min && f <= p->vco_max)
64			break;
65		i++;
66	} while (i < 8);
67
68	if (i >= 8)
69		return vco;
70
71	vco.s = p->idx2s[i];
72
73	/*
74	 * Now find the closest divisor combination
75	 * which gives a PLL output of 'f'.
76	 */
77	for (rd = p->rd_min; rd <= p->rd_max; rd++) {
78		unsigned long fref_div, f_pll;
79		unsigned int vd;
80		int f_diff;
81
82		fref_div = (2 * p->ref) / rd;
83
84		vd = (f + fref_div / 2) / fref_div;
85		if (vd < p->vd_min || vd > p->vd_max)
86			continue;
87
88		f_pll = fref_div * vd;
89		f_diff = f_pll - f;
90		if (f_diff < 0)
91			f_diff = -f_diff;
92
93		if ((unsigned)f_diff < best) {
94			vco.v = vd - 8;
95			vco.r = rd - 2;
96			if (f_diff == 0)
97				break;
98			best = f_diff;
99		}
100	}
101
102	return vco;
103}
104
105EXPORT_SYMBOL(icst_hz_to_vco);
106