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kernel
os
linux
clocksource: add DBX500 PRCMU Timer support
This patch adds the DBX500 PRCMU Timer driver as a clocksource
and as sched_clock.
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Signed-off-by: Jonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
authored by
Mattias Wallin
and committed by
Linus Walleij
489bccea
cba13830
+142
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drivers/clocksource/Kconfig
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drivers/clocksource/Kconfig
···
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config DW_APB_TIMER
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bool
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config CLKSRC_DBX500_PRCMU
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bool "Clocksource PRCMU Timer"
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depends on UX500_SOC_DB5500 || UX500_SOC_DB8500
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default y
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help
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Use the always on PRCMU Timer as clocksource
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config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
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bool "Clocksource PRCMU Timer sched_clock"
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depends on (CLKSRC_DBX500_PRCMU && !NOMADIK_MTU_SCHED_CLOCK)
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select HAVE_SCHED_CLOCK
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default y
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help
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Use the always on PRCMU Timer as sched_clock
+1
drivers/clocksource/Makefile
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drivers/clocksource/Makefile
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drivers/clocksource/clksrc-dbx500-prcmu.c
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drivers/clocksource/clksrc-dbx500-prcmu.c
···
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/*
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* Copyright (C) ST-Ericsson SA 2011
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*
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* License Terms: GNU General Public License v2
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* Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson
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* Author: Sundar Iyer for ST-Ericsson
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* sched_clock implementation is based on:
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* plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com>
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*
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* DBx500-PRCMU Timer
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* The PRCMU has 5 timers which are available in a always-on
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* power domain. We use the Timer 4 for our always-on clock
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* source on DB8500 and Timer 3 on DB5500.
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*/
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#include <linux/clockchips.h>
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#include <linux/clksrc-dbx500-prcmu.h>
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#include <asm/sched_clock.h>
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#include <mach/setup.h>
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#include <mach/hardware.h>
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#define RATE_32K 32768
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#define TIMER_MODE_CONTINOUS 0x1
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#define TIMER_DOWNCOUNT_VAL 0xffffffff
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#define PRCMU_TIMER_REF 0
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#define PRCMU_TIMER_DOWNCOUNT 0x4
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#define PRCMU_TIMER_MODE 0x8
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#define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */
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void __iomem *clksrc_dbx500_timer_base;
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static cycle_t clksrc_dbx500_prcmu_read(struct clocksource *cs)
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{
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u32 count, count2;
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do {
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count = readl(clksrc_dbx500_timer_base +
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PRCMU_TIMER_DOWNCOUNT);
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count2 = readl(clksrc_dbx500_timer_base +
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PRCMU_TIMER_DOWNCOUNT);
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} while (count2 != count);
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/* Negate because the timer is a decrementing counter */
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return ~count;
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}
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static struct clocksource clocksource_dbx500_prcmu = {
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.name = "dbx500-prcmu-timer",
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.rating = 300,
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.read = clksrc_dbx500_prcmu_read,
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.shift = 10,
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.mask = CLOCKSOURCE_MASK(32),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
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static DEFINE_CLOCK_DATA(cd);
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unsigned long long notrace sched_clock(void)
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{
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u32 cyc;
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if (unlikely(!clksrc_dbx500_timer_base))
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return 0;
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cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
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return cyc_to_sched_clock(&cd, cyc, (u32)~0);
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}
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static void notrace clksrc_dbx500_prcmu_update_sched_clock(void)
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{
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u32 cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
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update_sched_clock(&cd, cyc, (u32)~0);
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}
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#endif
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void __init clksrc_dbx500_prcmu_init(void)
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{
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/*
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* The A9 sub system expects the timer to be configured as
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* a continous looping timer.
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* The PRCMU should configure it but if it for some reason
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* don't we do it here.
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*/
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if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) !=
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TIMER_MODE_CONTINOUS) {
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writel(TIMER_MODE_CONTINOUS,
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clksrc_dbx500_timer_base + PRCMU_TIMER_MODE);
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writel(TIMER_DOWNCOUNT_VAL,
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clksrc_dbx500_timer_base + PRCMU_TIMER_REF);
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}
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#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
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init_sched_clock(&cd, clksrc_dbx500_prcmu_update_sched_clock,
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32, RATE_32K);
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#endif
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clocksource_calc_mult_shift(&clocksource_dbx500_prcmu,
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RATE_32K, SCHED_CLOCK_MIN_WRAP);
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clocksource_register(&clocksource_dbx500_prcmu);
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}
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include/linux/clksrc-dbx500-prcmu.h
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include/linux/clksrc-dbx500-prcmu.h
···
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/*
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* Copyright (C) ST-Ericsson SA 2011
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*
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* License Terms: GNU General Public License v2
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* Author: Mattias Wallin <mattias.wallin@stericsson.com>
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*
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*/
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#ifndef __CLKSRC_DBX500_PRCMU_H
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#define __CLKSRC_DBX500_PRCMU_H
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#include <linux/init.h>
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#include <linux/io.h>
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extern void __iomem *clksrc_dbx500_timer_base;
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#ifdef CONFIG_CLKSRC_DBX500_PRCMU
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void __init clksrc_dbx500_prcmu_init(void);
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#else
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void __init clksrc_dbx500_prcmu_init(void) {}
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#endif
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#endif