62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
/*
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* Copyright (c) 2017 Jean-Paul Etienne <fractalclone@gmail.com>
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* Copyright (c) 2017 Palmer Dabbelt <palmer@dabbelt.com>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/init.h>
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#include <zephyr/devicetree.h>
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#include "prci.h"
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#define CORECLK_HZ (DT_PROP(DT_NODELABEL(coreclk), clock_frequency))
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BUILD_ASSERT(DT_PROP(DT_NODELABEL(tlclk), clock_div) == 1,
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"Unsupported TLCLK divider");
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static int fe310_clock_init(void)
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{
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/*
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* HFXOSC (16 MHz) is used to produce coreclk (and therefore tlclk /
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* peripheral clock). This code supports the following frequencies:
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* - 16 MHz (bypass HFPLL).
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* - 48 MHz - 320 MHz, in 8 MHz steps (use HFPLL).
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*/
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BUILD_ASSERT(MHZ(16) == CORECLK_HZ ||
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(MHZ(48) <= CORECLK_HZ && MHZ(320) >= CORECLK_HZ &&
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(CORECLK_HZ % MHZ(8)) == 0),
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"Unsupported CORECLK frequency");
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uint32_t prci;
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if (MHZ(16) == CORECLK_HZ) {
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/* Bypass HFPLL. */
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prci = PLL_REFSEL(1) | PLL_BYPASS(1);
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} else {
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/* refr = 8 MHz. */
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const int pll_r = 0x1;
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int pll_q;
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/* Select Q divisor to produce vco on [384 MHz, 768 MHz]. */
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if (MHZ(768) / 8 >= CORECLK_HZ) {
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pll_q = 0x3;
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} else if (MHZ(768) / 4 >= CORECLK_HZ) {
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pll_q = 0x2;
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} else {
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pll_q = 0x1;
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}
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/* Select F multiplier to produce vco target. */
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const int pll_f = ((CORECLK_HZ / MHZ(1)) >> (4 - pll_q)) - 1;
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prci = PLL_REFSEL(1) | PLL_R(pll_r) | PLL_F(pll_f) | PLL_Q(pll_q);
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}
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PRCI_REG(PRCI_PLLCFG) = prci;
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PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
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PRCI_REG(PRCI_PLLCFG) |= PLL_SEL(1);
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PRCI_REG(PRCI_HFROSCCFG) &= ~ROSC_EN(1);
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return 0;
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}
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SYS_INIT(fe310_clock_init, PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
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