Root/arch/arm/common/icst.c

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

Archive Download this file



interactive