/* * linux/arch/arm/common/icst525.c * * Copyright (C) 2003 Deep Blue Solutions, Ltd, All Rights Reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * Support functions for calculating clocks/divisors for the ICST525 * clock generators. See http://www.icst.com/ for more information * on these devices. */ #include <linux/module.h> #include <linux/kernel.h> #include <asm/hardware/icst525.h> /* * Divisors for each OD setting. */ static unsigned char s2div[8] = { 10, 2, 8, 4, 5, 7, 9, 6 }; unsigned long icst525_khz(const struct icst525_params *p, struct icst525_vco vco) { return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * s2div[vco.s]); } EXPORT_SYMBOL(icst525_khz); /* * Ascending divisor S values. */ static unsigned char idx2s[] = { 1, 3, 4, 7, 5, 2, 6, 0 }; struct icst525_vco icst525_khz_to_vco(const struct icst525_params *p, unsigned long freq) { struct icst525_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 * s2div[idx2s[i]]; /* * f must be between 10MHz and * 320MHz (5V) or 200MHz (3V) */ if (f > 10000 && f <= p->vco_max) break; } while (i < ARRAY_SIZE(idx2s)); if (i >= ARRAY_SIZE(idx2s)) return vco; vco.s = 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(icst525_khz_to_vco); struct icst525_vco icst525_ps_to_vco(const struct icst525_params *p, unsigned long period) { struct icst525_vco vco = { .s = 1, .v = p->vd_max, .r = p->rd_max }; unsigned long f, ps; unsigned int i = 0, rd, best = (unsigned int)-1; ps = 1000000000UL / p->vco_max; /* * First, find the PLL output divisor such * that the PLL output is within spec. */ do { f = period / s2div[idx2s[i]]; /* * f must be between 10MHz and * 320MHz (5V) or 200MHz (3V) */ if (f >= ps && f < 100000) break; } while (i < ARRAY_SIZE(idx2s)); if (i >= ARRAY_SIZE(idx2s)) return vco; vco.s = idx2s[i]; ps = 500000000UL / p->ref; /* * 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 f_in_div, f_pll; unsigned int vd; int f_diff; f_in_div = ps * rd; vd = (f_in_div + f / 2) / f; if (vd < p->vd_min || vd > p->vd_max) continue; f_pll = (f_in_div + vd / 2) / 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(icst525_ps_to_vco);