86 lines
2.2 KiB
C
86 lines
2.2 KiB
C
/**
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* @file
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* @brief Provide @ref clocksource functionality for OMAP
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*
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* @ref clocksource provides a neat architecture. all we do is
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* To loop in with Sync 32Khz clock ticking away at 32768hz on OMAP.
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* Sync 32Khz clock is an always ON clock.
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*
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* (C) Copyright 2008
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* Texas Instruments, <www.ti.com>
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* Nishanth Menon <x0nishan@ti.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <common.h>
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#include <clock.h>
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#include <init.h>
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#include <io.h>
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#include <mach/omap3-silicon.h>
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#include <mach/omap4-silicon.h>
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#include <mach/clocks.h>
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#include <mach/timers.h>
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#include <mach/sys_info.h>
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#include <mach/syslib.h>
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/** Sync 32Khz Timer registers */
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#define S32K_CR 0x10
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#define S32K_FREQUENCY 32768
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static void __iomem *timerbase;
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/**
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* @brief Provide a simple clock read
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*
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* Nothing is simpler.. read direct from clock and provide it
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* to the caller.
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*
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* @return S32K clock counter
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*/
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static uint64_t s32k_clocksource_read(void)
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{
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return readl(timerbase + S32K_CR);
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}
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/* A bit obvious isn't it? */
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static struct clocksource s32k_cs = {
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.read = s32k_clocksource_read,
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.mask = CLOCKSOURCE_MASK(32),
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.shift = 10,
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};
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/**
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* @brief Initialize the Clock
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*
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* There is nothing to do on OMAP as SYNC32K clock is
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* always on, and we do a simple data structure initialization.
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* 32K clock gives 32768 ticks a seconds
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*
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* @return result of @ref init_clock
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*/
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static int s32k_clocksource_init(void)
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{
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if (IS_ENABLED(CONFIG_ARCH_OMAP3))
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timerbase = (void *)OMAP3_32KTIMER_BASE;
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else if (IS_ENABLED(CONFIG_ARCH_OMAP4))
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timerbase = (void *)OMAP44XX_32KTIMER_BASE;
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else
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BUG();
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s32k_cs.mult = clocksource_hz2mult(S32K_FREQUENCY, s32k_cs.shift);
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return init_clock(&s32k_cs);
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}
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/* Run me at boot time */
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core_initcall(s32k_clocksource_init);
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