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102 lines
2.3 KiB
102 lines
2.3 KiB
// 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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