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/*
* [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
*
* 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 <config.h>
#include <asm/arch/hardware.h>
#include <asm/arch/at91_pmc.h>
#include <asm/arch/clk.h>
#include <asm/arch/io.h>
static unsigned long cpu_clk_rate_hz;
static unsigned long main_clk_rate_hz;
static unsigned long mck_rate_hz;
static unsigned long plla_rate_hz;
static unsigned long pllb_rate_hz;
static u32 at91_pllb_usb_init;
unsigned long get_cpu_clk_rate(void)
{
return cpu_clk_rate_hz;
}
unsigned long get_main_clk_rate(void)
{
return main_clk_rate_hz;
}
unsigned long get_mck_clk_rate(void)
{
return mck_rate_hz;
}
unsigned long get_plla_clk_rate(void)
{
return plla_rate_hz;
}
unsigned long get_pllb_clk_rate(void)
{
return pllb_rate_hz;
}
u32 get_pllb_init(void)
{
return at91_pllb_usb_init;
}
static unsigned long at91_css_to_rate(unsigned long css)
{
switch (css) {
case AT91_PMC_CSS_SLOW:
return AT91_SLOW_CLOCK;
case AT91_PMC_CSS_MAIN:
return main_clk_rate_hz;
case AT91_PMC_CSS_PLLA:
return plla_rate_hz;
case AT91_PMC_CSS_PLLB:
return 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 defined(CONFIG_AT91SAM9G20)
if (input < 2000000)
continue;
#endif
if (input < 100000)
continue;
if (input > 32000000)
continue;
mul1 = out_freq / input;
#if defined(CONFIG_AT91SAM9G20)
if (mul > 63)
continue;
#endif
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;
#ifndef 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 = at91_sys_read(AT91_CKGR_MCFR);
} while (!(tmp & AT91_PMC_MAINRDY));
main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
}
#endif
main_clk_rate_hz = main_clock;
/* report if PLLA is more than mildly overclocked */
plla_rate_hz = at91_pll_rate(main_clock, at91_sys_read(AT91_CKGR_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!
*/
at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
AT91_PMC_USB96M;
pllb_rate_hz = at91_pll_rate(main_clock, at91_pllb_usb_init);
#endif
/*
* MCK and CPU derive from one of those primary clocks.
* For now, assume this parentage won't change.
*/
mckr = at91_sys_read(AT91_PMC_MCKR);
freq = mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_CSS);
freq /= (1 << ((mckr & AT91_PMC_PRES) >> 2)); /* prescale */
#if defined(CONFIG_AT91RM9200)
mck_rate_hz = freq / (1 + ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
#elif defined(CONFIG_AT91SAM9G20)
mck_rate_hz = (mckr & AT91_PMC_MDIV) ?
freq / ((mckr & AT91_PMC_MDIV) >> 7) : freq; /* mdiv ; (x >> 7) = ((x >> 8) * 2) */
if (mckr & AT91_PMC_PDIV)
freq /= 2; /* processor clock division */
#else
mck_rate_hz = freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
#endif
cpu_clk_rate_hz = freq;
return 0;
}
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