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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 *dummy)
{
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();
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction tmu_irq = {
.name = "timer",
.handler = tmu_timer_interrupt,
.flags = IRQF_DISABLED,
.mask = CPU_MASK_NONE,
};
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_start(void)
{
ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);
return 0;
}
static int tmu_timer_stop(void)
{
ctrl_outb(0, TMU_TSTR);
return 0;
}
static int tmu_timer_init(void)
{
unsigned long interval;
setup_irq(CONFIG_SH_TIMER_IRQ, &tmu_irq);
tmu0_clk.parent = clk_get("module_clk");
/* Start TMU0 */
tmu_timer_stop();
#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);
tmu_timer_start();
return 0;
}
struct sys_timer_ops tmu_timer_ops = {
.init = tmu_timer_init,
.start = tmu_timer_start,
.stop = tmu_timer_stop,
#ifndef CONFIG_GENERIC_TIME
.get_offset = tmu_timer_get_offset,
#endif
};
struct sys_timer tmu_timer = {
.name = "tmu",
.ops = &tmu_timer_ops,
};
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