1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * linux/arch/arm/common/icst307.c
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Support functions for calculating clocks/divisors for the ICST307
8*4882a593Smuzhiyun * clock generators. See https://www.idt.com/ for more information
9*4882a593Smuzhiyun * on these devices.
10*4882a593Smuzhiyun *
11*4882a593Smuzhiyun * This is an almost identical implementation to the ICST525 clock generator.
12*4882a593Smuzhiyun * The s2div and idx2s files are different
13*4882a593Smuzhiyun */
14*4882a593Smuzhiyun #include <linux/module.h>
15*4882a593Smuzhiyun #include <linux/kernel.h>
16*4882a593Smuzhiyun #include <asm/div64.h>
17*4882a593Smuzhiyun #include "icst.h"
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun /*
20*4882a593Smuzhiyun * Divisors for each OD setting.
21*4882a593Smuzhiyun */
22*4882a593Smuzhiyun const unsigned char icst307_s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 };
23*4882a593Smuzhiyun const unsigned char icst525_s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
24*4882a593Smuzhiyun EXPORT_SYMBOL(icst307_s2div);
25*4882a593Smuzhiyun EXPORT_SYMBOL(icst525_s2div);
26*4882a593Smuzhiyun
icst_hz(const struct icst_params * p,struct icst_vco vco)27*4882a593Smuzhiyun unsigned long icst_hz(const struct icst_params *p, struct icst_vco vco)
28*4882a593Smuzhiyun {
29*4882a593Smuzhiyun u64 dividend = p->ref * 2 * (u64)(vco.v + 8);
30*4882a593Smuzhiyun u32 divisor = (vco.r + 2) * p->s2div[vco.s];
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun do_div(dividend, divisor);
33*4882a593Smuzhiyun return (unsigned long)dividend;
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun EXPORT_SYMBOL(icst_hz);
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun /*
39*4882a593Smuzhiyun * Ascending divisor S values.
40*4882a593Smuzhiyun */
41*4882a593Smuzhiyun const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 };
42*4882a593Smuzhiyun const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 };
43*4882a593Smuzhiyun EXPORT_SYMBOL(icst307_idx2s);
44*4882a593Smuzhiyun EXPORT_SYMBOL(icst525_idx2s);
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun struct icst_vco
icst_hz_to_vco(const struct icst_params * p,unsigned long freq)47*4882a593Smuzhiyun icst_hz_to_vco(const struct icst_params *p, unsigned long freq)
48*4882a593Smuzhiyun {
49*4882a593Smuzhiyun struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
50*4882a593Smuzhiyun unsigned long f;
51*4882a593Smuzhiyun unsigned int i = 0, rd, best = (unsigned int)-1;
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun /*
54*4882a593Smuzhiyun * First, find the PLL output divisor such
55*4882a593Smuzhiyun * that the PLL output is within spec.
56*4882a593Smuzhiyun */
57*4882a593Smuzhiyun do {
58*4882a593Smuzhiyun f = freq * p->s2div[p->idx2s[i]];
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun if (f > p->vco_min && f <= p->vco_max)
61*4882a593Smuzhiyun break;
62*4882a593Smuzhiyun i++;
63*4882a593Smuzhiyun } while (i < 8);
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun if (i >= 8)
66*4882a593Smuzhiyun return vco;
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun vco.s = p->idx2s[i];
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun /*
71*4882a593Smuzhiyun * Now find the closest divisor combination
72*4882a593Smuzhiyun * which gives a PLL output of 'f'.
73*4882a593Smuzhiyun */
74*4882a593Smuzhiyun for (rd = p->rd_min; rd <= p->rd_max; rd++) {
75*4882a593Smuzhiyun unsigned long fref_div, f_pll;
76*4882a593Smuzhiyun unsigned int vd;
77*4882a593Smuzhiyun int f_diff;
78*4882a593Smuzhiyun
79*4882a593Smuzhiyun fref_div = (2 * p->ref) / rd;
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun vd = (f + fref_div / 2) / fref_div;
82*4882a593Smuzhiyun if (vd < p->vd_min || vd > p->vd_max)
83*4882a593Smuzhiyun continue;
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun f_pll = fref_div * vd;
86*4882a593Smuzhiyun f_diff = f_pll - f;
87*4882a593Smuzhiyun if (f_diff < 0)
88*4882a593Smuzhiyun f_diff = -f_diff;
89*4882a593Smuzhiyun
90*4882a593Smuzhiyun if ((unsigned)f_diff < best) {
91*4882a593Smuzhiyun vco.v = vd - 8;
92*4882a593Smuzhiyun vco.r = rd - 2;
93*4882a593Smuzhiyun if (f_diff == 0)
94*4882a593Smuzhiyun break;
95*4882a593Smuzhiyun best = f_diff;
96*4882a593Smuzhiyun }
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun return vco;
100*4882a593Smuzhiyun }
101*4882a593Smuzhiyun
102*4882a593Smuzhiyun EXPORT_SYMBOL(icst_hz_to_vco);
103