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[POWERPC] Implement generic time of day clocksource for powerpc

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Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Tony Breeds 2007-09-22 07:35:52 +10:00 committed by Paul Mackerras
parent aa3be5f32d
commit 4a4cfe3836
2 changed files with 104 additions and 172 deletions
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6
arch/powerpc/Kconfig
View File

@ -29,6 +29,12 @@ config MMU
config GENERIC_CMOS_UPDATE
def_bool y
config GENERIC_TIME
def_bool y
config GENERIC_TIME_VSYSCALL
def_bool y
config GENERIC_HARDIRQS
bool
default y

270
arch/powerpc/kernel/time.c
View File

@ -65,17 +65,44 @@
#include <asm/div64.h>
#include <asm/smp.h>
#include <asm/vdso_datapage.h>
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#endif
#ifdef CONFIG_PPC_ISERIES
#include <asm/iseries/it_lp_queue.h>
#include <asm/iseries/hv_call_xm.h>
#endif
/* powerpc clocksource/clockevent code */
#include <linux/clocksource.h>
static cycle_t rtc_read(void);
static struct clocksource clocksource_rtc = {
.name = "rtc",
.rating = 400,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.mask = CLOCKSOURCE_MASK(64),
.shift = 22,
.mult = 0, /* To be filled in */
.read = rtc_read,
};
static cycle_t timebase_read(void);
static struct clocksource clocksource_timebase = {
.name = "timebase",
.rating = 400,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.mask = CLOCKSOURCE_MASK(64),
.shift = 22,
.mult = 0, /* To be filled in */
.read = timebase_read,
};
#ifdef CONFIG_PPC_ISERIES
static unsigned long __initdata iSeries_recal_titan;
static signed long __initdata iSeries_recal_tb;
/* Forward declaration is only needed for iSereis compiles */
void __init clocksource_init(void);
#endif
#define XSEC_PER_SEC (1024*1024)
@ -343,65 +370,6 @@ void udelay(unsigned long usecs)
}
EXPORT_SYMBOL(udelay);
/*
* This version of gettimeofday has microsecond resolution.
*/
static inline void __do_gettimeofday(struct timeval *tv)
{
unsigned long sec, usec;
u64 tb_ticks, xsec;
struct gettimeofday_vars *temp_varp;
u64 temp_tb_to_xs, temp_stamp_xsec;
/*
* These calculations are faster (gets rid of divides)
* if done in units of 1/2^20 rather than microseconds.
* The conversion to microseconds at the end is done
* without a divide (and in fact, without a multiply)
*/
temp_varp = do_gtod.varp;
/* Sampling the time base must be done after loading
* do_gtod.varp in order to avoid racing with update_gtod.
*/
data_barrier(temp_varp);
tb_ticks = get_tb() - temp_varp->tb_orig_stamp;
temp_tb_to_xs = temp_varp->tb_to_xs;
temp_stamp_xsec = temp_varp->stamp_xsec;
xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
sec = xsec / XSEC_PER_SEC;
usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
usec = SCALE_XSEC(usec, 1000000);
tv->tv_sec = sec;
tv->tv_usec = usec;
}
void do_gettimeofday(struct timeval *tv)
{
if (__USE_RTC()) {
/* do this the old way */
unsigned long flags, seq;
unsigned int sec, nsec, usec;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
sec = xtime.tv_sec;
nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy);
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
usec = nsec / 1000;
while (usec >= 1000000) {
usec -= 1000000;
++sec;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
return;
}
__do_gettimeofday(tv);
}
EXPORT_SYMBOL(do_gettimeofday);
/*
* There are two copies of tb_to_xs and stamp_xsec so that no
@ -447,56 +415,6 @@ static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
++(vdso_data->tb_update_count);
}
/*
* When the timebase - tb_orig_stamp gets too big, we do a manipulation
* between tb_orig_stamp and stamp_xsec. The goal here is to keep the
* difference tb - tb_orig_stamp small enough to always fit inside a
* 32 bits number. This is a requirement of our fast 32 bits userland
* implementation in the vdso. If we "miss" a call to this function
* (interrupt latency, CPU locked in a spinlock, ...) and we end up
* with a too big difference, then the vdso will fallback to calling
* the syscall
*/
static __inline__ void timer_recalc_offset(u64 cur_tb)
{
unsigned long offset;
u64 new_stamp_xsec;
u64 tlen, t2x;
u64 tb, xsec_old, xsec_new;
struct gettimeofday_vars *varp;
if (__USE_RTC())
return;
tlen = current_tick_length();
offset = cur_tb - do_gtod.varp->tb_orig_stamp;
if (tlen == last_tick_len && offset < 0x80000000u)
return;
if (tlen != last_tick_len) {
t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs);
last_tick_len = tlen;
} else
t2x = do_gtod.varp->tb_to_xs;
new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
do_div(new_stamp_xsec, 1000000000);
new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
++vdso_data->tb_update_count;
smp_mb();
/*
* Make sure time doesn't go backwards for userspace gettimeofday.
*/
tb = get_tb();
varp = do_gtod.varp;
xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs)
+ varp->stamp_xsec;
xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec;
if (xsec_new < xsec_old)
new_stamp_xsec += xsec_old - xsec_new;
update_gtod(cur_tb, new_stamp_xsec, t2x);
}
#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
@ -568,6 +486,8 @@ static int __init iSeries_tb_recal(void)
iSeries_recal_titan = titan;
iSeries_recal_tb = tb;
/* Called here as now we know accurate values for the timebase */
clocksource_init();
return 0;
}
late_initcall(iSeries_tb_recal);
@ -650,7 +570,6 @@ void timer_interrupt(struct pt_regs * regs)
if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) {
tb_last_jiffy = tb_next_jiffy;
do_timer(1);
timer_recalc_offset(tb_last_jiffy);
}
write_sequnlock(&xtime_lock);
}
@ -722,66 +641,6 @@ unsigned long long sched_clock(void)
return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
}
int do_settimeofday(struct timespec *tv)
{
time_t wtm_sec, new_sec = tv->tv_sec;
long wtm_nsec, new_nsec = tv->tv_nsec;
unsigned long flags;
u64 new_xsec;
unsigned long tb_delta;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irqsave(&xtime_lock, flags);
/*
* Updating the RTC is not the job of this code. If the time is
* stepped under NTP, the RTC will be updated after STA_UNSYNC
* is cleared. Tools like clock/hwclock either copy the RTC
* to the system time, in which case there is no point in writing
* to the RTC again, or write to the RTC but then they don't call
* settimeofday to perform this operation.
*/
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_mb();
/*
* Subtract off the number of nanoseconds since the
* beginning of the last tick.
*/
tb_delta = tb_ticks_since(tb_last_jiffy);
tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
set_normalized_timespec(&xtime, new_sec, new_nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
ntp_clear();
new_xsec = xtime.tv_nsec;
if (new_xsec != 0) {
new_xsec *= XSEC_PER_SEC;
do_div(new_xsec, NSEC_PER_SEC);
}
new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC;
update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
write_sequnlock_irqrestore(&xtime_lock, flags);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
static int __init get_freq(char *name, int cells, unsigned long *val)
{
struct device_node *cpu;
@ -873,6 +732,69 @@ unsigned long read_persistent_clock(void)
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
/* clocksource code */
static cycle_t rtc_read(void)
{
return (cycle_t)get_rtc();
}
static cycle_t timebase_read(void)
{
return (cycle_t)get_tb();
}
void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
{
u64 t2x, stamp_xsec;
if (clock != &clocksource_timebase)
return;
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_mb();
/* XXX this assumes clock->shift == 22 */
/* 4611686018 ~= 2^(20+64-22) / 1e9 */
t2x = (u64) clock->mult * 4611686018ULL;
stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
do_div(stamp_xsec, 1000000000);
stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
update_gtod(clock->cycle_last, stamp_xsec, t2x);
}
void update_vsyscall_tz(void)
{
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_mb();
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
smp_mb();
++vdso_data->tb_update_count;
}
void __init clocksource_init(void)
{
struct clocksource *clock;
if (__USE_RTC())
clock = &clocksource_rtc;
else
clock = &clocksource_timebase;
clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift);
if (clocksource_register(clock)) {
printk(KERN_ERR "clocksource: %s is already registered\n",
clock->name);
return;
}
printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
clock->name, clock->mult, clock->shift);
}
/* This function is only called on the boot processor */
void __init time_init(void)
{
@ -982,6 +904,10 @@ void __init time_init(void)
write_sequnlock_irqrestore(&xtime_lock, flags);
/* Register the clocksource, if we're not running on iSeries */
if (!firmware_has_feature(FW_FEATURE_ISERIES))
clocksource_init();
/* Not exact, but the timer interrupt takes care of this */
set_dec(tb_ticks_per_jiffy);
}