778eeb1b19
Add new clocksource that uses the counter present on the MIPS Global Interrupt Controller. Signed-off-by: Steven J. Hill <sjhill@mips.com> Patchwork: http://patchwork.linux-mips.org/patch/4681/ Signed-off-by: John Crispin <blogic@openwrt.org>
49 lines
1.3 KiB
C
49 lines
1.3 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
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*/
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#include <linux/clocksource.h>
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#include <linux/init.h>
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#include <asm/time.h>
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#include <asm/gic.h>
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static cycle_t gic_hpt_read(struct clocksource *cs)
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{
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unsigned int hi, hi2, lo;
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do {
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GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_63_32), hi);
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GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), lo);
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GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_63_32), hi2);
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} while (hi2 != hi);
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return (((cycle_t) hi) << 32) + lo;
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}
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static struct clocksource gic_clocksource = {
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.name = "GIC",
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.read = gic_hpt_read,
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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void __init gic_clocksource_init(unsigned int frequency)
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{
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unsigned int config, bits;
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/* Calculate the clocksource mask. */
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GICREAD(GIC_REG(SHARED, GIC_SH_CONFIG), config);
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bits = 32 + ((config & GIC_SH_CONFIG_COUNTBITS_MSK) >>
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(GIC_SH_CONFIG_COUNTBITS_SHF - 2));
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/* Set clocksource mask. */
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gic_clocksource.mask = CLOCKSOURCE_MASK(bits);
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/* Calculate a somewhat reasonable rating value. */
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gic_clocksource.rating = 200 + frequency / 10000000;
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clocksource_register_hz(&gic_clocksource, frequency);
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}
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