158 lines
3.7 KiB
C
158 lines
3.7 KiB
C
/*
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* [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
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*
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* Copyright (C) 2011 Andreas Bießmann
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* Copyright (C) 2005 David Brownell
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* Copyright (C) 2005 Ivan Kokshaysky
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* Copyright (C) 2009 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/arch/hardware.h>
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#include <asm/arch/at91_pmc.h>
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#include <asm/arch/clk.h>
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#if !defined(CONFIG_AT91FAMILY)
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# error You need to define CONFIG_AT91FAMILY in your board config!
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#endif
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DECLARE_GLOBAL_DATA_PTR;
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static unsigned long at91_css_to_rate(unsigned long css)
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{
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switch (css) {
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case AT91_PMC_MCKR_CSS_SLOW:
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return CONFIG_SYS_AT91_SLOW_CLOCK;
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case AT91_PMC_MCKR_CSS_MAIN:
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return gd->arch.main_clk_rate_hz;
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case AT91_PMC_MCKR_CSS_PLLA:
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return gd->arch.plla_rate_hz;
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case AT91_PMC_MCKR_CSS_PLLB:
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return gd->arch.pllb_rate_hz;
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}
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return 0;
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}
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#ifdef CONFIG_USB_ATMEL
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static unsigned at91_pll_calc(unsigned main_freq, unsigned out_freq)
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{
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unsigned i, div = 0, mul = 0, diff = 1 << 30;
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unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
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/* PLL output max 240 MHz (or 180 MHz per errata) */
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if (out_freq > 240000000)
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goto fail;
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for (i = 1; i < 256; i++) {
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int diff1;
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unsigned input, mul1;
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/*
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* PLL input between 1MHz and 32MHz per spec, but lower
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* frequences seem necessary in some cases so allow 100K.
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* Warning: some newer products need 2MHz min.
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*/
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input = main_freq / i;
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if (input < 100000)
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continue;
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if (input > 32000000)
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continue;
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mul1 = out_freq / input;
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if (mul1 > 2048)
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continue;
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if (mul1 < 2)
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goto fail;
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diff1 = out_freq - input * mul1;
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if (diff1 < 0)
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diff1 = -diff1;
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if (diff > diff1) {
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diff = diff1;
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div = i;
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mul = mul1;
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if (diff == 0)
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break;
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}
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}
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if (i == 256 && diff > (out_freq >> 5))
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goto fail;
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return ret | ((mul - 1) << 16) | div;
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fail:
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return 0;
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}
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#endif
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static u32 at91_pll_rate(u32 freq, u32 reg)
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{
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unsigned mul, div;
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div = reg & 0xff;
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mul = (reg >> 16) & 0x7ff;
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if (div && mul) {
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freq /= div;
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freq *= mul + 1;
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} else
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freq = 0;
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return freq;
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}
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int at91_clock_init(unsigned long main_clock)
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{
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unsigned freq, mckr;
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at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC;
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#ifndef CONFIG_SYS_AT91_MAIN_CLOCK
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unsigned tmp;
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/*
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* When the bootloader initialized the main oscillator correctly,
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* there's no problem using the cycle counter. But if it didn't,
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* or when using oscillator bypass mode, we must be told the speed
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* of the main clock.
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*/
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if (!main_clock) {
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do {
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tmp = readl(&pmc->mcfr);
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} while (!(tmp & AT91_PMC_MCFR_MAINRDY));
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tmp &= AT91_PMC_MCFR_MAINF_MASK;
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main_clock = tmp * (CONFIG_SYS_AT91_SLOW_CLOCK / 16);
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}
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#endif
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gd->arch.main_clk_rate_hz = main_clock;
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/* report if PLLA is more than mildly overclocked */
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gd->arch.plla_rate_hz = at91_pll_rate(main_clock, readl(&pmc->pllar));
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#ifdef CONFIG_USB_ATMEL
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/*
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* USB clock init: choose 48 MHz PLLB value,
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* disable 48MHz clock during usb peripheral suspend.
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*
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* REVISIT: assumes MCK doesn't derive from PLLB!
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*/
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gd->arch.at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
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AT91_PMC_PLLBR_USBDIV_2;
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gd->arch.pllb_rate_hz = at91_pll_rate(main_clock,
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gd->arch.at91_pllb_usb_init);
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#endif
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/*
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* MCK and CPU derive from one of those primary clocks.
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* For now, assume this parentage won't change.
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*/
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mckr = readl(&pmc->mckr);
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gd->arch.mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
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freq = gd->arch.mck_rate_hz;
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freq /= (1 << ((mckr & AT91_PMC_MCKR_PRES_MASK) >> 2)); /* prescale */
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/* mdiv */
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gd->arch.mck_rate_hz = freq /
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(1 + ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
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gd->arch.cpu_clk_rate_hz = freq;
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return 0;
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}
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