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>
This commit is contained in:
Mattias Wallin 2011-05-27 10:30:12 +02:00 committed by Linus Walleij
parent cba13830d3
commit 489bccea63
4 changed files with 142 additions and 0 deletions

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@ -15,3 +15,18 @@ config CLKSRC_MMIO
config DW_APB_TIMER
bool
config CLKSRC_DBX500_PRCMU
bool "Clocksource PRCMU Timer"
depends on UX500_SOC_DB5500 || UX500_SOC_DB8500
default y
help
Use the always on PRCMU Timer as clocksource
config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
bool "Clocksource PRCMU Timer sched_clock"
depends on (CLKSRC_DBX500_PRCMU && !NOMADIK_MTU_SCHED_CLOCK)
select HAVE_SCHED_CLOCK
default y
help
Use the always on PRCMU Timer as sched_clock

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@ -9,3 +9,4 @@ obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.o
obj-$(CONFIG_CLKBLD_I8253) += i8253.o
obj-$(CONFIG_CLKSRC_MMIO) += mmio.o
obj-$(CONFIG_DW_APB_TIMER) += dw_apb_timer.o
obj-$(CONFIG_CLKSRC_DBX500_PRCMU) += clksrc-dbx500-prcmu.o

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@ -0,0 +1,104 @@
/*
* Copyright (C) ST-Ericsson SA 2011
*
* License Terms: GNU General Public License v2
* Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson
* Author: Sundar Iyer for ST-Ericsson
* sched_clock implementation is based on:
* plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com>
*
* DBx500-PRCMU Timer
* The PRCMU has 5 timers which are available in a always-on
* power domain. We use the Timer 4 for our always-on clock
* source on DB8500 and Timer 3 on DB5500.
*/
#include <linux/clockchips.h>
#include <linux/clksrc-dbx500-prcmu.h>
#include <asm/sched_clock.h>
#include <mach/setup.h>
#include <mach/hardware.h>
#define RATE_32K 32768
#define TIMER_MODE_CONTINOUS 0x1
#define TIMER_DOWNCOUNT_VAL 0xffffffff
#define PRCMU_TIMER_REF 0
#define PRCMU_TIMER_DOWNCOUNT 0x4
#define PRCMU_TIMER_MODE 0x8
#define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */
void __iomem *clksrc_dbx500_timer_base;
static cycle_t clksrc_dbx500_prcmu_read(struct clocksource *cs)
{
u32 count, count2;
do {
count = readl(clksrc_dbx500_timer_base +
PRCMU_TIMER_DOWNCOUNT);
count2 = readl(clksrc_dbx500_timer_base +
PRCMU_TIMER_DOWNCOUNT);
} while (count2 != count);
/* Negate because the timer is a decrementing counter */
return ~count;
}
static struct clocksource clocksource_dbx500_prcmu = {
.name = "dbx500-prcmu-timer",
.rating = 300,
.read = clksrc_dbx500_prcmu_read,
.shift = 10,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
static DEFINE_CLOCK_DATA(cd);
unsigned long long notrace sched_clock(void)
{
u32 cyc;
if (unlikely(!clksrc_dbx500_timer_base))
return 0;
cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
return cyc_to_sched_clock(&cd, cyc, (u32)~0);
}
static void notrace clksrc_dbx500_prcmu_update_sched_clock(void)
{
u32 cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
update_sched_clock(&cd, cyc, (u32)~0);
}
#endif
void __init clksrc_dbx500_prcmu_init(void)
{
/*
* The A9 sub system expects the timer to be configured as
* a continous looping timer.
* The PRCMU should configure it but if it for some reason
* don't we do it here.
*/
if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) !=
TIMER_MODE_CONTINOUS) {
writel(TIMER_MODE_CONTINOUS,
clksrc_dbx500_timer_base + PRCMU_TIMER_MODE);
writel(TIMER_DOWNCOUNT_VAL,
clksrc_dbx500_timer_base + PRCMU_TIMER_REF);
}
#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
init_sched_clock(&cd, clksrc_dbx500_prcmu_update_sched_clock,
32, RATE_32K);
#endif
clocksource_calc_mult_shift(&clocksource_dbx500_prcmu,
RATE_32K, SCHED_CLOCK_MIN_WRAP);
clocksource_register(&clocksource_dbx500_prcmu);
}

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@ -0,0 +1,22 @@
/*
* Copyright (C) ST-Ericsson SA 2011
*
* License Terms: GNU General Public License v2
* Author: Mattias Wallin <mattias.wallin@stericsson.com>
*
*/
#ifndef __CLKSRC_DBX500_PRCMU_H
#define __CLKSRC_DBX500_PRCMU_H
#include <linux/init.h>
#include <linux/io.h>
extern void __iomem *clksrc_dbx500_timer_base;
#ifdef CONFIG_CLKSRC_DBX500_PRCMU
void __init clksrc_dbx500_prcmu_init(void);
#else
void __init clksrc_dbx500_prcmu_init(void) {}
#endif
#endif