path: root/arch/sh/kernel/time_64.c

/*
 * arch/sh/kernel/time_64.c
 *
 * Copyright (C) 2000, 2001  Paolo Alberelli
 * Copyright (C) 2003 - 2007  Paul Mundt
 * Copyright (C) 2003  Richard Curnow
 *
 *    Original TMU/RTC code taken from sh version.
 *    Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
 *      Some code taken from i386 version.
 *      Copyright (C) 1991, 1992, 1995  Linus Torvalds
 *
 * 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/errno.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/bcd.h>
#include <linux/timex.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <cpu/registers.h>	 /* required by inline __asm__ stmt. */
#include <cpu/irq.h>
#include <asm/addrspace.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/delay.h>
#include <asm/clock.h>

#define TMU_TOCR_INIT	0x00
#define TMU0_TCR_INIT	0x0020
#define TMU_TSTR_INIT	1
#define TMU_TSTR_OFF	0

/* Time Management Unit */
#define	TMU_BLOCK_OFF	0x01020000
#define TMU_BASE	PHYS_PERIPHERAL_BLOCK + TMU_BLOCK_OFF
#define TMU0_BASE	tmu_base + 0x8 + (0xc * 0x0)
#define TMU1_BASE	tmu_base + 0x8 + (0xc * 0x1)
#define TMU2_BASE	tmu_base + 0x8 + (0xc * 0x2)

#define TMU_TOCR	tmu_base+0x0	/* Byte access */
#define TMU_TSTR	tmu_base+0x4	/* Byte access */

#define TMU0_TCOR	TMU0_BASE+0x0	/* Long access */
#define TMU0_TCNT	TMU0_BASE+0x4	/* Long access */
#define TMU0_TCR	TMU0_BASE+0x8	/* Word access */

#define TICK_SIZE (tick_nsec / 1000)

static unsigned long tmu_base;

/* Variables to allow interpolation of time of day to resolution better than a
 * jiffy. */

/* This is effectively protected by xtime_lock */
static unsigned long ctc_last_interrupt;
static unsigned long long usecs_per_jiffy = 1000000/HZ; /* Approximation */

#define CTC_JIFFY_SCALE_SHIFT 40

/* 2**CTC_JIFFY_SCALE_SHIFT / ctc_ticks_per_jiffy */
static unsigned long long scaled_recip_ctc_ticks_per_jiffy;

/* Estimate number of microseconds that have elapsed since the last timer tick,
   by scaling the delta that has occurred in the CTC register.

   WARNING WARNING WARNING : This algorithm relies on the CTC decrementing at
   the CPU clock rate.  If the CPU sleeps, the CTC stops counting.  Bear this
   in mind if enabling SLEEP_WORKS in process.c.  In that case, this algorithm
   probably needs to use TMU.TCNT0 instead.  This will work even if the CPU is
   sleeping, though will be coarser.

   FIXME : What if usecs_per_tick is moving around too much, e.g. if an adjtime
   is running or if the freq or tick arguments of adjtimex are modified after
   we have calibrated the scaling factor?  This will result in either a jump at
   the end of a tick period, or a wrap backwards at the start of the next one,
   if the application is reading the time of day often enough.  I think we
   ought to do better than this.  For this reason, usecs_per_jiffy is left
   separated out in the calculation below.  This allows some future hook into
   the adjtime-related stuff in kernel/timer.c to remove this hazard.

*/

static unsigned long usecs_since_tick(void)
{
	unsigned long long current_ctc;
	long ctc_ticks_since_interrupt;
	unsigned long long ull_ctc_ticks_since_interrupt;
	unsigned long result;

	unsigned long long mul1_out;
	unsigned long long mul1_out_high;
	unsigned long long mul2_out_low, mul2_out_high;

	/* Read CTC register */
	asm ("getcon cr62, %0" : "=r" (current_ctc));
	/* Note, the CTC counts down on each CPU clock, not up.
	   Note(2), use long type to get correct wraparound arithmetic when
	   the counter crosses zero. */
	ctc_ticks_since_interrupt = (long) ctc_last_interrupt - (long) current_ctc;
	ull_ctc_ticks_since_interrupt = (unsigned long long) ctc_ticks_since_interrupt;

	/* Inline assembly to do 32x32x32->64 multiplier */
	asm volatile ("mulu.l %1, %2, %0" :
	     "=r" (mul1_out) :
	     "r" (ull_ctc_ticks_since_interrupt), "r" (usecs_per_jiffy));

	mul1_out_high = mul1_out >> 32;

	asm volatile ("mulu.l %1, %2, %0" :
	     "=r" (mul2_out_low) :
	     "r" (mul1_out), "r" (scaled_recip_ctc_ticks_per_jiffy));

#if 1
	asm volatile ("mulu.l %1, %2, %0" :
	     "=r" (mul2_out_high) :
	     "r" (mul1_out_high), "r" (scaled_recip_ctc_ticks_per_jiffy));
#endif

	result = (unsigned long) (((mul2_out_high << 32) + mul2_out_low) >> CTC_JIFFY_SCALE_SHIFT);

	return result;
}

u32 arch_gettimeoffset(void)
{
	return usecs_since_tick() * 1000;
}

/* Dummy RTC ops */
static void null_rtc_get_time(struct timespec *tv)
{
	tv->tv_sec = mktime(2000, 1, 1, 0, 0, 0);
	tv->tv_nsec = 0;
}

static int null_rtc_set_time(const time_t secs)
{
	return 0;
}

void (*rtc_sh_get_time)(struct timespec *) = null_rtc_get_time;
int (*rtc_sh_set_time)(const time_t) = null_rtc_set_time;

/* last time the RTC clock got updated */
static long last_rtc_update;

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
static inline void do_timer_interrupt(void)
{
	unsigned long long current_ctc;

	if (current->pid)
		profile_tick(CPU_PROFILING);

	/*
	 * 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);
	asm ("getcon cr62, %0" : "=r" (current_ctc));
	ctc_last_interrupt = (unsigned long) current_ctc;

	do_timer(1);

	/*
	 * If we have an externally synchronized Linux clock, then update
	 * RTC clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	 * called as close as possible to 500 ms before the new second starts.
	 */
	if (ntp_synced() &&
	    xtime.tv_sec > last_rtc_update + 660 &&
	    (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
	    (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
		if (rtc_sh_set_time(xtime.tv_sec) == 0)
			last_rtc_update = xtime.tv_sec;
		else
			/* do it again in 60 s */
			last_rtc_update = xtime.tv_sec - 600;
	}
	write_sequnlock(&xtime_lock);

#ifndef CONFIG_SMP
	update_process_times(user_mode(get_irq_regs()));
#endif
}

/*
 * This is the same as the above, except we _also_ save the current
 * Time Stamp Counter value at the time of the timer interrupt, so that
 * we later on can estimate the time of day more exactly.
 */
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
	unsigned long timer_status;

	/* Clear UNF bit */
	timer_status = ctrl_inw(TMU0_TCR);
	timer_status &= ~0x100;
	ctrl_outw(timer_status, TMU0_TCR);

	do_timer_interrupt();

	return IRQ_HANDLED;
}

static struct irqaction irq0  = {
	.handler = timer_interrupt,
	.flags = IRQF_DISABLED,
	.name = "timer",
};

void __init time_init(void)
{
	unsigned long interval;
	struct clk *clk;

	tmu_base = (unsigned long)ioremap_nocache(TMU_BASE, 1024);
	if (!tmu_base) {
		panic("Unable to remap TMU\n");
	}

	clk = clk_get(NULL, "cpu_clk");
	scaled_recip_ctc_ticks_per_jiffy = ((1ULL << CTC_JIFFY_SCALE_SHIFT) /
			(unsigned long long)(clk_get_rate(clk) / HZ));

	rtc_sh_get_time(&xtime);

	setup_irq(TIMER_IRQ, &irq0);

	clk = clk_get(NULL, "module_clk");
	interval = (clk_get_rate(clk)/(HZ*4));

	printk("Interval = %ld\n", interval);

	/* Start TMU0 */
	ctrl_outb(TMU_TSTR_OFF, TMU_TSTR);
	ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
	ctrl_outw(TMU0_TCR_INIT, TMU0_TCR);
	ctrl_outl(interval, TMU0_TCOR);
	ctrl_outl(interval, TMU0_TCNT);
	ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);
}