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/*
* arch/sh/kernel/timers/timer-tmu.c - TMU Timer Support
*
* Copyright (C) 2005 Paul Mundt
*
* TMU handling code hacked out of arch/sh/kernel/time.c
*
* Copyright (C) 1999 Tetsuya Okada & Niibe Yutaka
* Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
* Copyright (C) 2002, 2003, 2004 Paul Mundt
* Copyright (C) 2002 M. R. Brown <mrbrown@linux-sh.org>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <asm/timer.h>
#include <asm/rtc.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/clock.h>
#define TMU_TOCR_INIT 0x00
#define TMU0_TCR_INIT 0x0020
#define TMU_TSTR_INIT 1
#define TMU0_TCR_CALIB 0x0000
static DEFINE_SPINLOCK(tmu0_lock);
static unsigned long tmu_timer_get_offset(void)
{
int count;
unsigned long flags;
static int count_p = 0x7fffffff; /* for the first call after boot */
static unsigned long jiffies_p = 0;
/*
* cache volatile jiffies temporarily; we have IRQs turned off.
*/
unsigned long jiffies_t;
spin_lock_irqsave(&tmu0_lock, flags);
/* timer count may underflow right here */
count = ctrl_inl(TMU0_TCNT); /* read the latched count */
jiffies_t = jiffies;
/*
* avoiding timer inconsistencies (they are rare, but they happen)...
* there is one kind of problem that must be avoided here:
* 1. the timer counter underflows
*/
if (jiffies_t == jiffies_p) {
if (count > count_p) {
/* the nutcase */
if (ctrl_inw(TMU0_TCR) & 0x100) { /* Check UNF bit */
count -= LATCH;
} else {
printk("%s (): hardware timer problem?\n",
__FUNCTION__);
}
}
} else
jiffies_p = jiffies_t;
count_p = count;
spin_unlock_irqrestore(&tmu0_lock, flags);
count = ((LATCH-1) - count) * TICK_SIZE;
count = (count + LATCH/2) / LATCH;
return count;
}
static irqreturn_t tmu_timer_interrupt(int irq, void *dev_id,
struct pt_regs *regs)
{
unsigned long timer_status;
/* Clear UNF bit */
timer_status = ctrl_inw(TMU0_TCR);
timer_status &= ~0x100;
ctrl_outw(timer_status, TMU0_TCR);
/*
* Here we are in the timer irq handler. We just have irqs locally
* disabled but we don't know if the timer_bh is running on the other
* CPU. We need to avoid to SMP race with it. NOTE: we don' t need
* the irq version of write_lock because as just said we have irq
* locally disabled. -arca
*/
write_seqlock(&xtime_lock);
handle_timer_tick(regs);
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction tmu_irq = {
.name = "timer",
.handler = tmu_timer_interrupt,
.flags = SA_INTERRUPT,
.mask = CPU_MASK_NONE,
};
/*
* Hah! We'll see if this works (switching from usecs to nsecs).
*/
static unsigned long tmu_timer_get_frequency(void)
{
u32 freq;
struct timespec ts1, ts2;
unsigned long diff_nsec;
unsigned long factor;
/* Setup the timer: We don't want to generate interrupts, just
* have it count down at its natural rate.
*/
ctrl_outb(0, TMU_TSTR);
#if !defined(CONFIG_CPU_SUBTYPE_SH7300) && !defined(CONFIG_CPU_SUBTYPE_SH7760)
ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
#endif
ctrl_outw(TMU0_TCR_CALIB, TMU0_TCR);
ctrl_outl(0xffffffff, TMU0_TCOR);
ctrl_outl(0xffffffff, TMU0_TCNT);
rtc_get_time(&ts2);
do {
rtc_get_time(&ts1);
} while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec);
/* actually start the timer */
ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);
do {
rtc_get_time(&ts2);
} while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec);
freq = 0xffffffff - ctrl_inl(TMU0_TCNT);
if (ts2.tv_nsec < ts1.tv_nsec) {
ts2.tv_nsec += 1000000000;
ts2.tv_sec--;
}
diff_nsec = (ts2.tv_sec - ts1.tv_sec) * 1000000000 + (ts2.tv_nsec - ts1.tv_nsec);
/* this should work well if the RTC has a precision of n Hz, where
* n is an integer. I don't think we have to worry about the other
* cases. */
factor = (1000000000 + diff_nsec/2) / diff_nsec;
if (factor * diff_nsec > 1100000000 ||
factor * diff_nsec < 900000000)
panic("weird RTC (diff_nsec %ld)", diff_nsec);
return freq * factor;
}
static void tmu_clk_init(struct clk *clk)
{
u8 divisor = TMU0_TCR_INIT & 0x7;
ctrl_outw(TMU0_TCR_INIT, TMU0_TCR);
clk->rate = clk->parent->rate / (4 << (divisor << 1));
}
static void tmu_clk_recalc(struct clk *clk)
{
u8 divisor = ctrl_inw(TMU0_TCR) & 0x7;
clk->rate = clk->parent->rate / (4 << (divisor << 1));
}
static struct clk_ops tmu_clk_ops = {
.init = tmu_clk_init,
.recalc = tmu_clk_recalc,
};
static struct clk tmu0_clk = {
.name = "tmu0_clk",
.ops = &tmu_clk_ops,
};
static int tmu_timer_init(void)
{
unsigned long interval;
setup_irq(TIMER_IRQ, &tmu_irq);
tmu0_clk.parent = clk_get("module_clk");
/* Start TMU0 */
ctrl_outb(0, TMU_TSTR);
#if !defined(CONFIG_CPU_SUBTYPE_SH7300) && !defined(CONFIG_CPU_SUBTYPE_SH7760)
ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
#endif
clk_register(&tmu0_clk);
clk_enable(&tmu0_clk);
interval = (clk_get_rate(&tmu0_clk) + HZ / 2) / HZ;
printk(KERN_INFO "Interval = %ld\n", interval);
ctrl_outl(interval, TMU0_TCOR);
ctrl_outl(interval, TMU0_TCNT);
ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);
return 0;
}
struct sys_timer_ops tmu_timer_ops = {
.init = tmu_timer_init,
.get_frequency = tmu_timer_get_frequency,
.get_offset = tmu_timer_get_offset,
};
struct sys_timer tmu_timer = {
.name = "tmu",
.ops = &tmu_timer_ops,
};
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