[PATCH] sh: Simple timer framework

#

# Makefile for the various Linux/SuperH timers

#

obj-y	:= timer.o

obj-$(CONFIG_SH_TMU)		+= timer-tmu.o

/*

 * 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,

};

/*

 * arch/sh/kernel/timers/timer.c - Common timer code

 *

 *  Copyright (C) 2005  Paul Mundt

 *

 * 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/kernel.h>

#include <linux/init.h>

#include <linux/timer.h>

#include <linux/string.h>

#include <asm/timer.h>

static struct sys_timer *sys_timers[] __initdata = {

#ifdef CONFIG_SH_TMU

	&tmu_timer,

#endif

	NULL,

};

static char timer_override[10] __initdata;

static int __init timer_setup(char *str)

{

	if (str)

		strlcpy(timer_override, str, sizeof(timer_override));

	return 1;

}

__setup("timer=", timer_setup);

struct sys_timer *get_sys_timer(void)

{

	int i;

	for (i = 0; i < ARRAY_SIZE(sys_timers); i++) {

		struct sys_timer *t = sys_timers[i];

		if (unlikely(!t))

			break;

		if (unlikely(timer_override[0]))

			if ((strcmp(timer_override, t->name) != 0))

				continue;

		if (likely(t->ops->init() == 0))

			return t;

	}

	return NULL;

}

#ifndef __ASM_SH_TIMER_H

#define __ASM_SH_TIMER_H

#include <linux/sysdev.h>

#include <asm/cpu/timer.h>

struct sys_timer_ops {

	int (*init)(void);

	unsigned long (*get_offset)(void);

	unsigned long (*get_frequency)(void);

};

struct sys_timer {

	const char		*name;

	struct sys_device	dev;

	struct sys_timer_ops	*ops;

};

#define TICK_SIZE (tick_nsec / 1000)

extern struct sys_timer tmu_timer;

extern struct sys_timer *sys_timer;

static inline unsigned long get_timer_offset(void)

{

	return sys_timer->ops->get_offset();

}

static inline unsigned long get_timer_frequency(void)

{

	return sys_timer->ops->get_frequency();

}

/* arch/sh/kernel/timers/timer.c */

struct sys_timer *get_sys_timer(void);

/* arch/sh/kernel/time.c */

void handle_timer_tick(struct pt_regs *);

#endif /* __ASM_SH_TIMER_H */