diff options
author | Linus Walleij <linus.walleij@linaro.org> | 2017-02-01 10:41:43 +0100 |
---|---|---|
committer | Linus Walleij <linus.walleij@linaro.org> | 2017-04-07 11:58:12 +0200 |
commit | ba3fae06c7a4e80ab9d48a8a045b352da97cf23d (patch) | |
tree | 83e6a470906ce711128e8927d87a7d467b402dcf /drivers/clk/versatile/icst.c | |
parent | b6acb2e4d934afffafb318a5c342243a482b25f1 (diff) |
ARM/clk: move the ICST library to drivers/clk
This moves the ICST clock divider helper library from
arch/arm/common to drivers/clk/versatile so it is maintained
with the other clock drivers.
We keep the structure as a helper library intact and do not
fuse it with the clk-icst.c Versatile ICST clock driver: there
may be other users out there that need to use this library for
their clocking, and then it will be helpful to keep the
library contained. (The icst.[c|h] files could just be moved
to drivers/clk/lib or a similar location to share the library.)
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/clk/versatile/icst.c')
-rw-r--r-- | drivers/clk/versatile/icst.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/drivers/clk/versatile/icst.c b/drivers/clk/versatile/icst.c new file mode 100644 index 000000000000..de2af63a3aad --- /dev/null +++ b/drivers/clk/versatile/icst.c @@ -0,0 +1,105 @@ +/* + * 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.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); |