diff options
Diffstat (limited to 'arch/arm/common/icst307.c')
| -rw-r--r-- | arch/arm/common/icst307.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/arch/arm/common/icst307.c b/arch/arm/common/icst307.c new file mode 100644 index 00000000000..bafe8b19be8 --- /dev/null +++ b/arch/arm/common/icst307.c @@ -0,0 +1,161 @@ +/* + * linux/arch/arm/common/icst307.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 ICST307 + * clock generators. See http://www.icst.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/hardware/icst307.h> + +/* + * Divisors for each OD setting. + */ +static unsigned char s2div[8] = { 10, 2, 8, 4, 5, 7, 3, 6 }; + +unsigned long icst307_khz(const struct icst307_params *p, struct icst307_vco vco) +{ + return p->ref * 2 * (vco.v + 8) / ((vco.r + 2) * s2div[vco.s]); +} + +EXPORT_SYMBOL(icst307_khz); + +/* + * Ascending divisor S values. + */ +static unsigned char idx2s[8] = { 1, 6, 3, 4, 7, 5, 2, 0 }; + +struct icst307_vco +icst307_khz_to_vco(const struct icst307_params *p, unsigned long freq) +{ + struct icst307_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 6MHz and 200MHz (3.3 or 5V) + */ + if (f > 6000 && 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(icst307_khz_to_vco); + +struct icst307_vco +icst307_ps_to_vco(const struct icst307_params *p, unsigned long period) +{ + struct icst307_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 6MHz and 200MHz (3.3 or 5V) + */ + if (f >= ps && f < 1000000000UL / 6000 + 1) + 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(icst307_ps_to_vco); |