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 */
25 const unsigned char icst307_s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 };
26 const unsigned char icst525_s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
27 EXPORT_SYMBOL(icst307_s2div);
28 EXPORT_SYMBOL(icst525_s2div);
29
icst_hz(const struct icst_params * p,struct icst_vco vco)30 unsigned 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
39 EXPORT_SYMBOL(icst_hz);
40
41 /*
42 * Ascending divisor S values.
43 */
44 const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 };
45 const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 };
46 EXPORT_SYMBOL(icst307_idx2s);
47 EXPORT_SYMBOL(icst525_idx2s);
48
49 struct icst_vco
icst_hz_to_vco(const struct icst_params * p,unsigned long freq)50 icst_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
105 EXPORT_SYMBOL(icst_hz_to_vco);
106