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/*
* [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
*
* Copyright (C) 2011 Andreas Bießmann
* Copyright (C) 2005 David Brownell
* Copyright (C) 2005 Ivan Kokshaysky
* Copyright (C) 2009 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <common.h>
#include <asm/io.h>
#include <asm/arch/hardware.h>
#include <asm/arch/at91_pmc.h>
#include <asm/arch/clk.h>
#if !defined(CONFIG_AT91FAMILY)
# error You need to define CONFIG_AT91FAMILY in your board config!
#endif
DECLARE_GLOBAL_DATA_PTR;
static unsigned long at91_css_to_rate(unsigned long css)
{
switch (css) {
case AT91_PMC_MCKR_CSS_SLOW:
return CONFIG_SYS_AT91_SLOW_CLOCK;
case AT91_PMC_MCKR_CSS_MAIN:
return gd->arch.main_clk_rate_hz;
case AT91_PMC_MCKR_CSS_PLLA:
return gd->arch.plla_rate_hz;
case AT91_PMC_MCKR_CSS_PLLB:
return gd->arch.pllb_rate_hz;
}
return 0;
}
#ifdef CONFIG_USB_ATMEL
static unsigned at91_pll_calc(unsigned main_freq, unsigned out_freq)
{
unsigned i, div = 0, mul = 0, diff = 1 << 30;
unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
/* PLL output max 240 MHz (or 180 MHz per errata) */
if (out_freq > 240000000)
goto fail;
for (i = 1; i < 256; i++) {
int diff1;
unsigned input, mul1;
/*
* PLL input between 1MHz and 32MHz per spec, but lower
* frequences seem necessary in some cases so allow 100K.
* Warning: some newer products need 2MHz min.
*/
input = main_freq / i;
if (input < 100000)
continue;
if (input > 32000000)
continue;
mul1 = out_freq / input;
if (mul1 > 2048)
continue;
if (mul1 < 2)
goto fail;
diff1 = out_freq - input * mul1;
if (diff1 < 0)
diff1 = -diff1;
if (diff > diff1) {
diff = diff1;
div = i;
mul = mul1;
if (diff == 0)
break;
}
}
if (i == 256 && diff > (out_freq >> 5))
goto fail;
return ret | ((mul - 1) << 16) | div;
fail:
return 0;
}
#endif
static u32 at91_pll_rate(u32 freq, u32 reg)
{
unsigned mul, div;
div = reg & 0xff;
mul = (reg >> 16) & 0x7ff;
if (div && mul) {
freq /= div;
freq *= mul + 1;
} else
freq = 0;
return freq;
}
int at91_clock_init(unsigned long main_clock)
{
unsigned freq, mckr;
at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC;
#ifndef CONFIG_SYS_AT91_MAIN_CLOCK
unsigned tmp;
/*
* When the bootloader initialized the main oscillator correctly,
* there's no problem using the cycle counter. But if it didn't,
* or when using oscillator bypass mode, we must be told the speed
* of the main clock.
*/
if (!main_clock) {
do {
tmp = readl(&pmc->mcfr);
} while (!(tmp & AT91_PMC_MCFR_MAINRDY));
tmp &= AT91_PMC_MCFR_MAINF_MASK;
main_clock = tmp * (CONFIG_SYS_AT91_SLOW_CLOCK / 16);
}
#endif
gd->arch.main_clk_rate_hz = main_clock;
/* report if PLLA is more than mildly overclocked */
gd->arch.plla_rate_hz = at91_pll_rate(main_clock, readl(&pmc->pllar));
#ifdef CONFIG_USB_ATMEL
/*
* USB clock init: choose 48 MHz PLLB value,
* disable 48MHz clock during usb peripheral suspend.
*
* REVISIT: assumes MCK doesn't derive from PLLB!
*/
gd->arch.at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
AT91_PMC_PLLBR_USBDIV_2;
gd->arch.pllb_rate_hz = at91_pll_rate(main_clock,
gd->arch.at91_pllb_usb_init);
#endif
/*
* MCK and CPU derive from one of those primary clocks.
* For now, assume this parentage won't change.
*/
mckr = readl(&pmc->mckr);
gd->arch.mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
freq = gd->arch.mck_rate_hz;
freq /= (1 << ((mckr & AT91_PMC_MCKR_PRES_MASK) >> 2)); /* prescale */
/* mdiv */
gd->arch.mck_rate_hz = freq /
(1 + ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
gd->arch.cpu_clk_rate_hz = freq;
return 0;
}
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