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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 | ||
27 | unsigned long icst307_khz(const struct icst307_params *p, struct icst307_vco vco) | |
28 | { | |
29 | return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * s2div[vco.s]); | |
30 | } | |
31 | ||
32 | EXPORT_SYMBOL(icst307_khz); | |
33 | ||
34 | /* | |
35 | * Ascending divisor S values. | |
36 | */ | |
37 | static unsigned char idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 }; | |
38 | ||
39 | struct icst307_vco | |
40 | icst307_khz_to_vco(const struct icst307_params *p, unsigned long freq) | |
41 | { | |
42 | struct icst307_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max }; | |
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 | */ | |
56 | if (f > 6000 && f <= p->vco_max) | |
57 | break; | |
58 | } while (i < ARRAY_SIZE(idx2s)); | |
59 | ||
60 | if (i > ARRAY_SIZE(idx2s)) | |
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 | ||
97 | EXPORT_SYMBOL(icst307_khz_to_vco); | |
98 | ||
99 | struct icst307_vco | |
100 | icst307_ps_to_vco(const struct icst307_params *p, unsigned long period) | |
101 | { | |
102 | struct icst307_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max }; | |
103 | unsigned long f, ps; | |
104 | unsigned int i = 0, rd, best = (unsigned int)-1; | |
105 | ||
106 | ps = 1000000000UL / p->vco_max; | |
107 | ||
108 | /* | |
109 | * First, find the PLL output divisor such | |
110 | * that the PLL output is within spec. | |
111 | */ | |
112 | do { | |
113 | f = period / s2div[idx2s[i]]; | |
114 | ||
115 | /* | |
116 | * f must be between 6MHz and 200MHz (3.3 or 5V) | |
117 | */ | |
118 | if (f >= ps && f < 1000000000UL / 6000 + 1) | |
119 | break; | |
120 | } while (i < ARRAY_SIZE(idx2s)); | |
121 | ||
122 | if (i > ARRAY_SIZE(idx2s)) | |
123 | return vco; | |
124 | ||
125 | vco.s = idx2s[i]; | |
126 | ||
127 | ps = 500000000UL / p->ref; | |
128 | ||
129 | /* | |
130 | * Now find the closest divisor combination | |
131 | * which gives a PLL output of 'f'. | |
132 | */ | |
133 | for (rd = p->rd_min; rd <= p->rd_max; rd++) { | |
134 | unsigned long f_in_div, f_pll; | |
135 | unsigned int vd; | |
136 | int f_diff; | |
137 | ||
138 | f_in_div = ps * rd; | |
139 | ||
140 | vd = (f_in_div + f / 2) / f; | |
141 | if (vd < p->vd_min || vd > p->vd_max) | |
142 | continue; | |
143 | ||
144 | f_pll = (f_in_div + vd / 2) / vd; | |
145 | f_diff = f_pll - f; | |
146 | if (f_diff < 0) | |
147 | f_diff = -f_diff; | |
148 | ||
149 | if ((unsigned)f_diff < best) { | |
150 | vco.v = vd - 8; | |
151 | vco.r = rd - 2; | |
152 | if (f_diff == 0) | |
153 | break; | |
154 | best = f_diff; | |
155 | } | |
156 | } | |
157 | ||
158 | return vco; | |
159 | } | |
160 | ||
161 | EXPORT_SYMBOL(icst307_ps_to_vco); |