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1da177e4 LT |
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.icst.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/icst307.h> | |
21 | ||
22 | /* | |
23 | * Divisors for each OD setting. | |
24 | */ | |
25 | static unsigned char s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 }; | |
26 | ||
64fceb1d | 27 | unsigned long icst307_hz(const struct icst_params *p, struct icst_vco vco) |
1da177e4 LT |
28 | { |
29 | return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * s2div[vco.s]); | |
30 | } | |
31 | ||
64fceb1d | 32 | EXPORT_SYMBOL(icst307_hz); |
1da177e4 LT |
33 | |
34 | /* | |
35 | * Ascending divisor S values. | |
36 | */ | |
37 | static unsigned char idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 }; | |
38 | ||
39c0cb02 | 39 | struct icst_vco |
64fceb1d | 40 | icst307_hz_to_vco(const struct icst_params *p, unsigned long freq) |
1da177e4 | 41 | { |
39c0cb02 | 42 | struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max }; |
1da177e4 LT |
43 | unsigned long f; |
44 | unsigned int i = 0, rd, best = (unsigned int)-1; | |
45 | ||
46 | /* | |
47 | * First, find the PLL output divisor such | |
48 | * that the PLL output is within spec. | |
49 | */ | |
50 | do { | |
51 | f = freq * s2div[idx2s[i]]; | |
52 | ||
53 | /* | |
54 | * f must be between 6MHz and 200MHz (3.3 or 5V) | |
55 | */ | |
e73a46a3 | 56 | if (f > p->vco_min && f <= p->vco_max) |
1da177e4 LT |
57 | break; |
58 | } while (i < ARRAY_SIZE(idx2s)); | |
59 | ||
d1d8f7de | 60 | if (i >= ARRAY_SIZE(idx2s)) |
1da177e4 LT |
61 | return vco; |
62 | ||
63 | vco.s = idx2s[i]; | |
64 | ||
65 | /* | |
66 | * Now find the closest divisor combination | |
67 | * which gives a PLL output of 'f'. | |
68 | */ | |
69 | for (rd = p->rd_min; rd <= p->rd_max; rd++) { | |
70 | unsigned long fref_div, f_pll; | |
71 | unsigned int vd; | |
72 | int f_diff; | |
73 | ||
74 | fref_div = (2 * p->ref) / rd; | |
75 | ||
76 | vd = (f + fref_div / 2) / fref_div; | |
77 | if (vd < p->vd_min || vd > p->vd_max) | |
78 | continue; | |
79 | ||
80 | f_pll = fref_div * vd; | |
81 | f_diff = f_pll - f; | |
82 | if (f_diff < 0) | |
83 | f_diff = -f_diff; | |
84 | ||
85 | if ((unsigned)f_diff < best) { | |
86 | vco.v = vd - 8; | |
87 | vco.r = rd - 2; | |
88 | if (f_diff == 0) | |
89 | break; | |
90 | best = f_diff; | |
91 | } | |
92 | } | |
93 | ||
94 | return vco; | |
95 | } | |
96 | ||
64fceb1d | 97 | EXPORT_SYMBOL(icst307_hz_to_vco); |