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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/common/icst307.c
*
* Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved.
*
* Support functions for calculating clocks/divisors for the ICST307
* clock generators. See http://www.idt.com/ for more information
* on these devices.
*
* This is an almost identical implementation to the ICST525 clock generator.
* The s2div and idx2s files are different
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <asm/div64.h>
#include "icst.h"
/*
* Divisors for each OD setting.
*/
const unsigned char icst307_s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 };
const unsigned char icst525_s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 };
EXPORT_SYMBOL(icst307_s2div);
EXPORT_SYMBOL(icst525_s2div);
unsigned long icst_hz(const struct icst_params *p, struct icst_vco vco)
{
u64 dividend = p->ref * 2 * (u64)(vco.v + 8);
u32 divisor = (vco.r + 2) * p->s2div[vco.s];
do_div(dividend, divisor);
return (unsigned long)dividend;
}
EXPORT_SYMBOL(icst_hz);
/*
* Ascending divisor S values.
*/
const unsigned char icst307_idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 };
const unsigned char icst525_idx2s[8] = { 1, 3, 4, 7, 5, 2, 6, 0 };
EXPORT_SYMBOL(icst307_idx2s);
EXPORT_SYMBOL(icst525_idx2s);
struct icst_vco
icst_hz_to_vco(const struct icst_params *p, unsigned long freq)
{
struct icst_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max };
unsigned long f;
unsigned int i = 0, rd, best = (unsigned int)-1;
/*
* First, find the PLL output divisor such
* that the PLL output is within spec.
*/
do {
f = freq * p->s2div[p->idx2s[i]];
if (f > p->vco_min && f <= p->vco_max)
break;
i++;
} while (i < 8);
if (i >= 8)
return vco;
vco.s = p->idx2s[i];
/*
* Now find the closest divisor combination
* which gives a PLL output of 'f'.
*/
for (rd = p->rd_min; rd <= p->rd_max; rd++) {
unsigned long fref_div, f_pll;
unsigned int vd;
int f_diff;
fref_div = (2 * p->ref) / rd;
vd = (f + fref_div / 2) / fref_div;
if (vd < p->vd_min || vd > p->vd_max)
continue;
f_pll = fref_div * vd;
f_diff = f_pll - f;
if (f_diff < 0)
f_diff = -f_diff;
if ((unsigned)f_diff < best) {
vco.v = vd - 8;
vco.r = rd - 2;
if (f_diff == 0)
break;
best = f_diff;
}
}
return vco;
}
EXPORT_SYMBOL(icst_hz_to_vco);
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