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/***************************************************************************/
/*
* sltimers.c -- generic ColdFire slice timer support.
*
* Copyright (C) 2009-2010, Philippe De Muyter <phdm@macqel.be>
* based on
* timers.c -- generic ColdFire hardware timer support.
* Copyright (C) 1999-2008, Greg Ungerer <gerg@snapgear.com>
*/
/***************************************************************************/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/profile.h>
#include <linux/clocksource.h>
#include <asm/io.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/coldfire.h>
#include <asm/mcfslt.h>
#include <asm/mcfsim.h>
/***************************************************************************/
#ifdef CONFIG_HIGHPROFILE
/*
* By default use Slice Timer 1 as the profiler clock timer.
*/
#define PA(a) (MCFSLT_TIMER1 + (a))
/*
* Choose a reasonably fast profile timer. Make it an odd value to
* try and get good coverage of kernel operations.
*/
#define PROFILEHZ 1013
irqreturn_t mcfslt_profile_tick(int irq, void *dummy)
{
/* Reset Slice Timer 1 */
__raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, PA(MCFSLT_SSR));
if (current->pid)
profile_tick(CPU_PROFILING);
return IRQ_HANDLED;
}
static struct irqaction mcfslt_profile_irq = {
.name = "profile timer",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = mcfslt_profile_tick,
};
void mcfslt_profile_init(void)
{
printk(KERN_INFO "PROFILE: lodging TIMER 1 @ %dHz as profile timer\n",
PROFILEHZ);
setup_irq(MCF_IRQ_PROFILER, &mcfslt_profile_irq);
/* Set up TIMER 2 as high speed profile clock */
__raw_writel(MCF_BUSCLK / PROFILEHZ - 1, PA(MCFSLT_STCNT));
__raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
PA(MCFSLT_SCR));
}
#endif /* CONFIG_HIGHPROFILE */
/***************************************************************************/
/*
* By default use Slice Timer 0 as the system clock timer.
*/
#define TA(a) (MCFSLT_TIMER0 + (a))
static u32 mcfslt_cycles_per_jiffy;
static u32 mcfslt_cnt;
static irq_handler_t timer_interrupt;
static irqreturn_t mcfslt_tick(int irq, void *dummy)
{
/* Reset Slice Timer 0 */
__raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, TA(MCFSLT_SSR));
mcfslt_cnt += mcfslt_cycles_per_jiffy;
return timer_interrupt(irq, dummy);
}
static struct irqaction mcfslt_timer_irq = {
.name = "timer",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = mcfslt_tick,
};
static cycle_t mcfslt_read_clk(struct clocksource *cs)
{
unsigned long flags;
u32 cycles, scnt;
local_irq_save(flags);
scnt = __raw_readl(TA(MCFSLT_SCNT));
cycles = mcfslt_cnt;
if (__raw_readl(TA(MCFSLT_SSR)) & MCFSLT_SSR_TE) {
cycles += mcfslt_cycles_per_jiffy;
scnt = __raw_readl(TA(MCFSLT_SCNT));
}
local_irq_restore(flags);
/* subtract because slice timers count down */
return cycles + ((mcfslt_cycles_per_jiffy - 1) - scnt);
}
static struct clocksource mcfslt_clk = {
.name = "slt",
.rating = 250,
.read = mcfslt_read_clk,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
void hw_timer_init(irq_handler_t handler)
{
mcfslt_cycles_per_jiffy = MCF_BUSCLK / HZ;
/*
* The coldfire slice timer (SLT) runs from STCNT to 0 included,
* then STCNT again and so on. It counts thus actually
* STCNT + 1 steps for 1 tick, not STCNT. So if you want
* n cycles, initialize STCNT with n - 1.
*/
__raw_writel(mcfslt_cycles_per_jiffy - 1, TA(MCFSLT_STCNT));
__raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
TA(MCFSLT_SCR));
/* initialize mcfslt_cnt knowing that slice timers count down */
mcfslt_cnt = mcfslt_cycles_per_jiffy;
timer_interrupt = handler;
setup_irq(MCF_IRQ_TIMER, &mcfslt_timer_irq);
clocksource_register_hz(&mcfslt_clk, MCF_BUSCLK);
#ifdef CONFIG_HIGHPROFILE
mcfslt_profile_init();
#endif
}
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