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