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/*
* 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.
*/
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/clockchips.h>
#include <linux/sched_clock.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 */
static void __iomem *clksrc_dbx500_timer_base;
static cycle_t notrace clksrc_dbx500_prcmu_read(struct clocksource *cs)
{
void __iomem *base = clksrc_dbx500_timer_base;
u32 count, count2;
do {
count = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT);
count2 = readl_relaxed(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,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
static u64 notrace dbx500_prcmu_sched_clock_read(void)
{
if (unlikely(!clksrc_dbx500_timer_base))
return 0;
return clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
}
#endif
static int __init clksrc_dbx500_prcmu_init(struct device_node *node)
{
clksrc_dbx500_timer_base = of_iomap(node, 0);
/*
* 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
sched_clock_register(dbx500_prcmu_sched_clock_read, 32, RATE_32K);
#endif
return clocksource_register_hz(&clocksource_dbx500_prcmu, RATE_32K);
}
CLOCKSOURCE_OF_DECLARE_RET(dbx500_prcmu, "stericsson,db8500-prcmu-timer-4",
clksrc_dbx500_prcmu_init);
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