/*
* File: arch/blackfin/kernel/time.c
* Based on: none - original work
* Author:
*
* Created:
* Description: This file contains the bfin-specific time handling details.
* Most of the stuff is located in the machine specific files.
*
* Modified:
* Copyright 2004-2006 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see the file COPYING, or write
* to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/module.h>
#include <linux/profile.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/irq.h>
#include <asm/blackfin.h>
/* This is an NTP setting */
#define TICK_SIZE (tick_nsec / 1000)
static void time_sched_init(irqreturn_t(*timer_routine)
(int, void *));
static unsigned long gettimeoffset(void);
static struct irqaction bfin_timer_irq = {
.name = "BFIN Timer Tick",
.flags = IRQF_DISABLED
};
/*
* The way that the Blackfin core timer works is:
* - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
* - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
*
* If you take the fastest clock (1ns, or 1GHz to make the math work easier)
* 10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
* (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
* to use TSCALE, and program it to zero (which is pass CCLK through).
* If you feel like using it, try to keep HZ * TIMESCALE to some
* value that divides easy (like power of 2).
*/
#define TIME_SCALE 1
static void
time_sched_init(irqreturn_t(*timer_routine) (int, void *))
{
u32 tcount;
/* power up the timer, but don't enable it just yet */
bfin_write_TCNTL(1);
CSYNC();
/*
* the TSCALE prescaler counter.
*/
bfin_write_TSCALE((TIME_SCALE - 1));
tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
bfin_write_TPERIOD(tcount);
bfin_write_TCOUNT(tcount);
/* now enable the timer */
CSYNC();
bfin_write_TCNTL(7);
bfin_timer_irq.handler = (irq_handler_t)timer_routine;
/* call setup_irq instead of request_irq because request_irq calls
* kmalloc which has not been initialized yet
*/
setup_irq(IRQ_CORETMR, &bfin_timer_irq);
}
/*
* Should return useconds since last timer tick
*/
static unsigned long gettimeoffset(void)
{
unsigned long offset;
unsigned long clocks_per_jiffy;
clocks_per_jiffy = bfin_read_TPERIOD();
offset =
(clocks_per_jiffy -
bfin_read_TCOUNT()) / (((clocks_per_jiffy + 1) * HZ) /
USEC_PER_SEC);
/* Check if we just wrapped the counters and maybe missed a tick */
if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
&& (offset < (100000 / HZ / 2)))
offset += (USEC_PER_SEC / HZ);
return offset;
}
static inline int set_rtc_mmss(unsigned long nowtime)
{
return 0;
}
/*
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
*/
#ifdef CONFIG_CORE_TIMER_IRQ_L1
irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
#endif
irqreturn_t timer_interrupt(int irq, void *dummy)
{
/* last time the cmos clock got updated */
static long last_rtc_update;
write_seqlock(&xtime_lock);
do_timer(1);
profile_tick(CPU_PROFILING);
/*
* If we have an externally synchronized Linux clock, then update
* CMOS 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 / NSEC_PER_USEC) >=
500000 - ((unsigned)TICK_SIZE) / 2
&& (xtime.tv_nsec / NSEC_PER_USEC) <=
500000 + ((unsigned)TICK_SIZE) / 2) {
if (set_rtc_mmss(xtime.tv_sec) == 0)
last_rtc_update = xtime.tv_sec;
else
/* Do it again in 60s. */
last_rtc_update = xtime.tv_sec - 600;
}
write_sequnlock(&xtime_lock);
#ifndef CONFIG_SMP
update_process_times(user_mode(get_irq_regs()));
#endif
return IRQ_HANDLED;
}
void __init time_init(void)
{
time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
#ifdef CONFIG_RTC_DRV_BFIN
/* [#2663] hack to filter junk RTC values that would cause
* userspace to have to deal with time values greater than
* 2^31 seconds (which uClibc cannot cope with yet)
*/
if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
bfin_write_RTC_STAT(0);
}
#endif
/* Initialize xtime. From now on, xtime is updated with timer interrupts */
xtime.tv_sec = secs_since_1970;
xtime.tv_nsec = 0;
wall_to_monotonic.tv_sec = -xtime.tv_sec;
time_sched_init(timer_interrupt);
}
#ifndef CONFIG_GENERIC_TIME
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
unsigned long seq;
unsigned long usec, sec;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
usec = gettimeoffset();
sec = xtime.tv_sec;
usec += (xtime.tv_nsec / NSEC_PER_USEC);
}
while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
while (usec >= USEC_PER_SEC) {
usec -= USEC_PER_SEC;
sec++;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);
int do_settimeofday(struct timespec *tv)
{
time_t wtm_sec, sec = tv->tv_sec;
long wtm_nsec, nsec = tv->tv_nsec;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irq(&xtime_lock);
/*
* This is revolting. We need to set the xtime.tv_usec
* correctly. However, the value in this location is
* is value at the last tick.
* Discover what correction gettimeofday
* would have done, and then undo it!
*/
nsec -= (gettimeoffset() * NSEC_PER_USEC);
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
set_normalized_timespec(&xtime, sec, nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
ntp_clear();
write_sequnlock_irq(&xtime_lock);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
#endif /* !CONFIG_GENERIC_TIME */
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
}
