u-boot/arch/arm/cpu/armv7/at91/clock.c

/*
 * [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>
 * Copyright (C) 2013 Bo Shen <voice.shen@atmel.com>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#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;
	}

	return 0;
}

static u32 at91_pll_rate(u32 freq, u32 reg)
{
	unsigned mul, div;

	div = reg & 0xff;
	mul = (reg >> 18) & 0x7f;
	if (div && mul) {
		freq /= div;
		freq *= mul + 1;
	} else {
		freq = 0;
	}

	return freq;
}

int at91_clock_init(unsigned long main_clock)
{
	unsigned freq, mckr;
	struct at91_pmc *pmc = (struct at91_pmc *)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));

	/*
	 * MCK and CPU derive from one of those primary clocks.
	 * For now, assume this parentage won't change.
	 */
	mckr = readl(&pmc->mckr);

	/* plla divisor by 2 */
	if (mckr & (1 << 12))
		gd->arch.plla_rate_hz >>= 1;

	gd->arch.mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
	freq = gd->arch.mck_rate_hz;

	/* prescale */
	freq >>= mckr & AT91_PMC_MCKR_PRES_MASK;

	switch (mckr & AT91_PMC_MCKR_MDIV_MASK) {
	case AT91_PMC_MCKR_MDIV_2:
		gd->arch.mck_rate_hz = freq / 2;
		break;
	case AT91_PMC_MCKR_MDIV_3:
		gd->arch.mck_rate_hz = freq / 3;
		break;
	case AT91_PMC_MCKR_MDIV_4:
		gd->arch.mck_rate_hz = freq / 4;
		break;
	default:
		break;
	}

	gd->arch.cpu_clk_rate_hz = freq;

	return 0;
}

void at91_periph_clk_enable(int id)
{
	struct at91_pmc *pmc = (struct at91_pmc *)ATMEL_BASE_PMC;

	if (id > 31)
		writel(1 << (id - 32), &pmc->pcer1);
	else
		writel(1 << id, &pmc->pcer);
}