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/*
* Copyright (C) ST-Ericsson SA 2010
*
* License Terms: GNU General Public License v2
* Author: Sundar Iyer <sundar.iyer@stericsson.com> for ST-Ericsson
*
* DB8500-PRCM Timer
* The PRCM has 5 timers which are available in a always-on
* power domain. we use the Timer 5 for our always-on clock source.
*/
#include <linux/io.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/jiffies.h>
#include <mach/setup.h>
#include <mach/prcmu-regs.h>
#define RATE_32K (32768)
#define TIMER_MODE_CONTINOUS (0x1)
#define TIMER_DOWNCOUNT_VAL (0xffffffff)
/*
* clocksource: the prcm timer is a decrementing counters, so we negate
* the value being read.
*/
static cycle_t db8500_prcm_read_timer(void)
{
u32 count = readl(PRCM_TIMER_5_DOWNCOUNT);
return ~count;
}
static struct clocksource db8500_prcm_clksrc = {
.name = "db8500-prcm-timer5",
.rating = 500,
.read = db8500_prcm_read_timer,
.shift = 10,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
void __init db8500_prcm_timer_init(void)
{
/*
* The A9 sub system expects the timer to be configured as
* a continous looping timer. If this timer is not configured
* in such a mode, then do so.
* Later on, when the PRCM decides to init this timer, the A9
* can rest assure that it need not init the timer
*/
if (readl(PRCM_TIMER_5_MODE) != TIMER_MODE_CONTINOUS) {
writel(TIMER_MODE_CONTINOUS, PRCM_TIMER_5_MODE);
writel(TIMER_DOWNCOUNT_VAL, PRCM_TIMER_5_REF);
}
/* register the clock source */
db8500_prcm_clksrc.mult = clocksource_hz2mult(RATE_32K,
db8500_prcm_clksrc.shift);
clocksource_register(&db8500_prcm_clksrc);
return;
}
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