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872e439a45
linux/arch/powerpc/kernel/time.c
Paul Mackerras 872e439a45 powerpc/pseries: Re-enable dispatch trace log userspace interface 
Since the cpu accounting code uses the hypervisor dispatch trace log
now when CONFIG_VIRT_CPU_ACCOUNTING = y, the previous commit disabled
access to it via files in the /sys/kernel/debug/powerpc/dtl/ directory
in that case.  This restores those files.

To do this, we now have a hook that the cpu accounting code will call
as it processes each entry from the hypervisor dispatch trace log.
The code in dtl.c now uses that to fill up its ring buffer, rather
than having the hypervisor fill the ring buffer directly.

This also fixes dtl_file_read() to handle overflow conditions a bit
better and adds a spinlock to ensure that race conditions (multiple
processes opening or reading the file concurrently) are handled
correctly.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-09-02 14:07:32 +10:00

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/*
* Common time routines among all ppc machines.
*
* Written by Cort Dougan (cort@cs.nmt.edu) to merge
* Paul Mackerras' version and mine for PReP and Pmac.
* MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
* Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
*
* First round of bugfixes by Gabriel Paubert (paubert@iram.es)
* to make clock more stable (2.4.0-test5). The only thing
* that this code assumes is that the timebases have been synchronized
* by firmware on SMP and are never stopped (never do sleep
* on SMP then, nap and doze are OK).
*
* Speeded up do_gettimeofday by getting rid of references to
* xtime (which required locks for consistency). (mikejc@us.ibm.com)
*
* TODO (not necessarily in this file):
* - improve precision and reproducibility of timebase frequency
* measurement at boot time. (for iSeries, we calibrate the timebase
* against the Titan chip's clock.)
* - for astronomical applications: add a new function to get
* non ambiguous timestamps even around leap seconds. This needs
* a new timestamp format and a good name.
*
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
*
* 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.
*/
#include <linux/errno.h>
#include <linux/module.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/timex.h>
#include <linux/kernel_stat.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/cpu.h>
#include <linux/security.h>
#include <linux/percpu.h>
#include <linux/rtc.h>
#include <linux/jiffies.h>
#include <linux/posix-timers.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/perf_event.h>
#include <asm/trace.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/nvram.h>
#include <asm/cache.h>
#include <asm/machdep.h>
#include <asm/uaccess.h>
#include <asm/time.h>
#include <asm/prom.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/smp.h>
#include <asm/vdso_datapage.h>
#include <asm/firmware.h>
#include <asm/cputime.h>
#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/clockchips.h>
#include <linux/clocksource.h>
static cycle_t rtc_read(struct clocksource *);
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(struct clocksource *);
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,
};
#define DECREMENTER_MAX 0x7fffffff
static int decrementer_set_next_event(unsigned long evt,
struct clock_event_device *dev);
static void decrementer_set_mode(enum clock_event_mode mode,
struct clock_event_device *dev);
static struct clock_event_device decrementer_clockevent = {
.name = "decrementer",
.rating = 200,
.shift = 0, /* To be filled in */
.mult = 0, /* To be filled in */
.irq = 0,
.set_next_event = decrementer_set_next_event,
.set_mode = decrementer_set_mode,
.features = CLOCK_EVT_FEAT_ONESHOT,
};
struct decrementer_clock {
struct clock_event_device event;
u64 next_tb;
};
static DEFINE_PER_CPU(struct decrementer_clock, decrementers);
#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 */
static void __init clocksource_init(void);
#endif
#define XSEC_PER_SEC (1024*1024)
#ifdef CONFIG_PPC64
#define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
#else
/* compute ((xsec << 12) * max) >> 32 */
#define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
#endif
unsigned long tb_ticks_per_jiffy;
unsigned long tb_ticks_per_usec = 100; /* sane default */
EXPORT_SYMBOL(tb_ticks_per_usec);
unsigned long tb_ticks_per_sec;
EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL_GPL(rtc_lock);
static u64 tb_to_ns_scale __read_mostly;
static unsigned tb_to_ns_shift __read_mostly;
static unsigned long boot_tb __read_mostly;
extern struct timezone sys_tz;
static long timezone_offset;
unsigned long ppc_proc_freq;
EXPORT_SYMBOL(ppc_proc_freq);
unsigned long ppc_tb_freq;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
/*
* Factors for converting from cputime_t (timebase ticks) to
* jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
* These are all stored as 0.64 fixed-point binary fractions.
*/
u64 __cputime_jiffies_factor;
EXPORT_SYMBOL(__cputime_jiffies_factor);
u64 __cputime_msec_factor;
EXPORT_SYMBOL(__cputime_msec_factor);
u64 __cputime_sec_factor;
EXPORT_SYMBOL(__cputime_sec_factor);
u64 __cputime_clockt_factor;
EXPORT_SYMBOL(__cputime_clockt_factor);
DEFINE_PER_CPU(unsigned long, cputime_last_delta);
DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
cputime_t cputime_one_jiffy;
void (*dtl_consumer)(struct dtl_entry *, u64);
static void calc_cputime_factors(void)
{
struct div_result res;
div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
__cputime_jiffies_factor = res.result_low;
div128_by_32(1000, 0, tb_ticks_per_sec, &res);
__cputime_msec_factor = res.result_low;
div128_by_32(1, 0, tb_ticks_per_sec, &res);
__cputime_sec_factor = res.result_low;
div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
__cputime_clockt_factor = res.result_low;
}
/*
* Read the SPURR on systems that have it, otherwise the PURR,
* or if that doesn't exist return the timebase value passed in.
*/
static u64 read_spurr(u64 tb)
{
if (cpu_has_feature(CPU_FTR_SPURR))
return mfspr(SPRN_SPURR);
if (cpu_has_feature(CPU_FTR_PURR))
return mfspr(SPRN_PURR);
return tb;
}
#ifdef CONFIG_PPC_SPLPAR
/*
* Scan the dispatch trace log and count up the stolen time.
* Should be called with interrupts disabled.
*/
static u64 scan_dispatch_log(u64 stop_tb)
{
u64 i = local_paca->dtl_ridx;
struct dtl_entry *dtl = local_paca->dtl_curr;
struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
struct lppaca *vpa = local_paca->lppaca_ptr;
u64 tb_delta;
u64 stolen = 0;
u64 dtb;
if (i == vpa->dtl_idx)
return 0;
while (i < vpa->dtl_idx) {
if (dtl_consumer)
dtl_consumer(dtl, i);
dtb = dtl->timebase;
tb_delta = dtl->enqueue_to_dispatch_time +
dtl->ready_to_enqueue_time;
barrier();
if (i + N_DISPATCH_LOG < vpa->dtl_idx) {
/* buffer has overflowed */
i = vpa->dtl_idx - N_DISPATCH_LOG;
dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
continue;
}
if (dtb > stop_tb)
break;
stolen += tb_delta;
++i;
++dtl;
if (dtl == dtl_end)
dtl = local_paca->dispatch_log;
}
local_paca->dtl_ridx = i;
local_paca->dtl_curr = dtl;
return stolen;
}
/*
* Accumulate stolen time by scanning the dispatch trace log.
* Called on entry from user mode.
*/
void accumulate_stolen_time(void)
{
u64 sst, ust;
sst = scan_dispatch_log(get_paca()->starttime_user);
ust = scan_dispatch_log(get_paca()->starttime);
get_paca()->system_time -= sst;
get_paca()->user_time -= ust;
get_paca()->stolen_time += ust + sst;
}
static inline u64 calculate_stolen_time(u64 stop_tb)
{
u64 stolen = 0;
if (get_paca()->dtl_ridx != get_paca()->lppaca_ptr->dtl_idx) {
stolen = scan_dispatch_log(stop_tb);
get_paca()->system_time -= stolen;
}
stolen += get_paca()->stolen_time;
get_paca()->stolen_time = 0;
return stolen;
}
#else /* CONFIG_PPC_SPLPAR */
static inline u64 calculate_stolen_time(u64 stop_tb)
{
return 0;
}
#endif /* CONFIG_PPC_SPLPAR */
/*
* Account time for a transition between system, hard irq
* or soft irq state.
*/
void account_system_vtime(struct task_struct *tsk)
{
u64 now, nowscaled, delta, deltascaled;
unsigned long flags;
u64 stolen, udelta, sys_scaled, user_scaled;
local_irq_save(flags);
now = mftb();
nowscaled = read_spurr(now);
get_paca()->system_time += now - get_paca()->starttime;
get_paca()->starttime = now;
deltascaled = nowscaled - get_paca()->startspurr;
get_paca()->startspurr = nowscaled;
stolen = calculate_stolen_time(now);
delta = get_paca()->system_time;
get_paca()->system_time = 0;
udelta = get_paca()->user_time - get_paca()->utime_sspurr;
get_paca()->utime_sspurr = get_paca()->user_time;
/*
* Because we don't read the SPURR on every kernel entry/exit,
* deltascaled includes both user and system SPURR ticks.
* Apportion these ticks to system SPURR ticks and user
* SPURR ticks in the same ratio as the system time (delta)
* and user time (udelta) values obtained from the timebase
* over the same interval. The system ticks get accounted here;
* the user ticks get saved up in paca->user_time_scaled to be
* used by account_process_tick.
*/
sys_scaled = delta;
user_scaled = udelta;
if (deltascaled != delta + udelta) {
if (udelta) {
sys_scaled = deltascaled * delta / (delta + udelta);
user_scaled = deltascaled - sys_scaled;
} else {
sys_scaled = deltascaled;
}
}
get_paca()->user_time_scaled += user_scaled;
if (in_irq() || idle_task(smp_processor_id()) != tsk) {
account_system_time(tsk, 0, delta, sys_scaled);
if (stolen)
account_steal_time(stolen);
} else {
account_idle_time(delta + stolen);
}
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(account_system_vtime);
/*
* Transfer the user and system times accumulated in the paca
* by the exception entry and exit code to the generic process
* user and system time records.
* Must be called with interrupts disabled.
* Assumes that account_system_vtime() has been called recently
* (i.e. since the last entry from usermode) so that
* get_paca()->user_time_scaled is up to date.
*/
void account_process_tick(struct task_struct *tsk, int user_tick)
{
cputime_t utime, utimescaled;
utime = get_paca()->user_time;
utimescaled = get_paca()->user_time_scaled;
get_paca()->user_time = 0;
get_paca()->user_time_scaled = 0;
get_paca()->utime_sspurr = 0;
account_user_time(tsk, utime, utimescaled);
}
#else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
#define calc_cputime_factors()
#endif
void __delay(unsigned long loops)
{
unsigned long start;
int diff;
if (__USE_RTC()) {
start = get_rtcl();
do {
/* the RTCL register wraps at 1000000000 */
diff = get_rtcl() - start;
if (diff < 0)
diff += 1000000000;
} while (diff < loops);
} else {
start = get_tbl();
while (get_tbl() - start < loops)
HMT_low();
HMT_medium();
}
}
EXPORT_SYMBOL(__delay);
void udelay(unsigned long usecs)
{
__delay(tb_ticks_per_usec * usecs);
}
EXPORT_SYMBOL(udelay);
#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
unsigned long pc = instruction_pointer(regs);
if (in_lock_functions(pc))
return regs->link;
return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif
#ifdef CONFIG_PPC_ISERIES
/*
* This function recalibrates the timebase based on the 49-bit time-of-day
* value in the Titan chip. The Titan is much more accurate than the value
* returned by the service processor for the timebase frequency.
*/
static int __init iSeries_tb_recal(void)
{
unsigned long titan, tb;
/* Make sure we only run on iSeries */
if (!firmware_has_feature(FW_FEATURE_ISERIES))
return -ENODEV;
tb = get_tb();
titan = HvCallXm_loadTod();
if ( iSeries_recal_titan ) {
unsigned long tb_ticks = tb - iSeries_recal_tb;
unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
unsigned long new_tb_ticks_per_jiffy =
DIV_ROUND_CLOSEST(new_tb_ticks_per_sec, HZ);
long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
char sign = '+';
/* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
if ( tick_diff < 0 ) {
tick_diff = -tick_diff;
sign = '-';
}
if ( tick_diff ) {
if ( tick_diff < tb_ticks_per_jiffy/25 ) {
printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
new_tb_ticks_per_jiffy, sign, tick_diff );
tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
tb_ticks_per_sec = new_tb_ticks_per_sec;
calc_cputime_factors();
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
setup_cputime_one_jiffy();
}
else {
printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
" new tb_ticks_per_jiffy = %lu\n"
" old tb_ticks_per_jiffy = %lu\n",
new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
}
}
}
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);
/* Called from platform early init */
void __init iSeries_time_init_early(void)
{
iSeries_recal_tb = get_tb();
iSeries_recal_titan = HvCallXm_loadTod();
}
#endif /* CONFIG_PPC_ISERIES */
#ifdef CONFIG_PERF_EVENTS
/*
* 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
*/
#ifdef CONFIG_PPC64
static inline unsigned long test_perf_event_pending(void)
{
unsigned long x;
asm volatile("lbz %0,%1(13)"
: "=r" (x)
: "i" (offsetof(struct paca_struct, perf_event_pending)));
return x;
}
static inline void set_perf_event_pending_flag(void)
{
asm volatile("stb %0,%1(13)" : :
"r" (1),
"i" (offsetof(struct paca_struct, perf_event_pending)));
}
static inline void clear_perf_event_pending(void)
{
asm volatile("stb %0,%1(13)" : :
"r" (0),
"i" (offsetof(struct paca_struct, perf_event_pending)));
}
#else /* 32-bit */
DEFINE_PER_CPU(u8, perf_event_pending);
#define set_perf_event_pending_flag() __get_cpu_var(perf_event_pending) = 1
#define test_perf_event_pending() __get_cpu_var(perf_event_pending)
#define clear_perf_event_pending() __get_cpu_var(perf_event_pending) = 0
#endif /* 32 vs 64 bit */
void set_perf_event_pending(void)
{
preempt_disable();
set_perf_event_pending_flag();
set_dec(1);
preempt_enable();
}
#else /* CONFIG_PERF_EVENTS */
#define test_perf_event_pending() 0
#define clear_perf_event_pending()
#endif /* CONFIG_PERF_EVENTS */
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
* in the lppaca and call the hypervisor if the virtual
* decrementer is less than the current value in the hardware
* decrementer. (almost always the new decrementer value will
* be greater than the current hardware decementer so the hypervisor
* call will not be needed)
*/
/*
* timer_interrupt - gets called when the decrementer overflows,
* with interrupts disabled.
*/
void timer_interrupt(struct pt_regs * regs)
{
struct pt_regs *old_regs;
struct decrementer_clock *decrementer = &__get_cpu_var(decrementers);
struct clock_event_device *evt = &decrementer->event;
u64 now;
trace_timer_interrupt_entry(regs);
__get_cpu_var(irq_stat).timer_irqs++;
/* Ensure a positive value is written to the decrementer, or else
* some CPUs will continuue to take decrementer exceptions */
set_dec(DECREMENTER_MAX);
#if defined(CONFIG_PPC32) && defined(CONFIG_PMAC)
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);
#endif
old_regs = set_irq_regs(regs);
irq_enter();
if (test_perf_event_pending()) {
clear_perf_event_pending();
perf_event_do_pending();
}
#ifdef CONFIG_PPC_ISERIES
if (firmware_has_feature(FW_FEATURE_ISERIES))
get_lppaca()->int_dword.fields.decr_int = 0;
#endif
now = get_tb_or_rtc();
if (now >= decrementer->next_tb) {
decrementer->next_tb = ~(u64)0;
if (evt->event_handler)
evt->event_handler(evt);
} else {
now = decrementer->next_tb - now;
if (now <= DECREMENTER_MAX)
set_dec((int)now);
}
#ifdef CONFIG_PPC_ISERIES
if (firmware_has_feature(FW_FEATURE_ISERIES) && hvlpevent_is_pending())
process_hvlpevents();
#endif
#ifdef CONFIG_PPC64
/* collect purr register values often, for accurate calculations */
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
cu->current_tb = mfspr(SPRN_PURR);
}
#endif
irq_exit();
set_irq_regs(old_regs);
trace_timer_interrupt_exit(regs);
}
#ifdef CONFIG_SUSPEND
static void generic_suspend_disable_irqs(void)
{
/* Disable the decrementer, so that it doesn't interfere
* with suspending.
*/
set_dec(0x7fffffff);
local_irq_disable();
set_dec(0x7fffffff);
}
static void generic_suspend_enable_irqs(void)
{
local_irq_enable();
}
/* Overrides the weak version in kernel/power/main.c */
void arch_suspend_disable_irqs(void)
{
if (ppc_md.suspend_disable_irqs)
ppc_md.suspend_disable_irqs();
generic_suspend_disable_irqs();
}
/* Overrides the weak version in kernel/power/main.c */
void arch_suspend_enable_irqs(void)
{
generic_suspend_enable_irqs();
if (ppc_md.suspend_enable_irqs)
ppc_md.suspend_enable_irqs();
}
#endif
/*
* Scheduler clock - returns current time in nanosec units.
*
* Note: mulhdu(a, b) (multiply high double unsigned) returns
* the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
* are 64-bit unsigned numbers.
*/
unsigned long long sched_clock(void)
{
if (__USE_RTC())
return get_rtc();
return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
}
static int __init get_freq(char *name, int cells, unsigned long *val)
{
struct device_node *cpu;
const unsigned int *fp;
int found = 0;
/* The cpu node should have timebase and clock frequency properties */
cpu = of_find_node_by_type(NULL, "cpu");
if (cpu) {
fp = of_get_property(cpu, name, NULL);
if (fp) {
found = 1;
*val = of_read_ulong(fp, cells);
}
of_node_put(cpu);
}
return found;
}
/* should become __cpuinit when secondary_cpu_time_init also is */
void start_cpu_decrementer(void)
{
#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
/* Clear any pending timer interrupts */
mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
/* Enable decrementer interrupt */
mtspr(SPRN_TCR, TCR_DIE);
#endif /* defined(CONFIG_BOOKE) || defined(CONFIG_40x) */
}
void __init generic_calibrate_decr(void)
{
ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
!get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
printk(KERN_ERR "WARNING: Estimating decrementer frequency "
"(not found)\n");
}
ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
!get_freq("clock-frequency", 1, &ppc_proc_freq)) {
printk(KERN_ERR "WARNING: Estimating processor frequency "
"(not found)\n");
}
}
int update_persistent_clock(struct timespec now)
{
struct rtc_time tm;
if (!ppc_md.set_rtc_time)
return 0;
to_tm(now.tv_sec + 1 + timezone_offset, &tm);
tm.tm_year -= 1900;
tm.tm_mon -= 1;
return ppc_md.set_rtc_time(&tm);
}
static void __read_persistent_clock(struct timespec *ts)
{
struct rtc_time tm;
static int first = 1;
ts->tv_nsec = 0;
/* XXX this is a litle fragile but will work okay in the short term */
if (first) {
first = 0;
if (ppc_md.time_init)
timezone_offset = ppc_md.time_init();
/* get_boot_time() isn't guaranteed to be safe to call late */
if (ppc_md.get_boot_time) {
ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
return;
}
}
if (!ppc_md.get_rtc_time) {
ts->tv_sec = 0;
return;
}
ppc_md.get_rtc_time(&tm);
ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
void read_persistent_clock(struct timespec *ts)
{
__read_persistent_clock(ts);
/* Sanitize it in case real time clock is set below EPOCH */
if (ts->tv_sec < 0) {
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
}
/* clocksource code */
static cycle_t rtc_read(struct clocksource *cs)
{
return (cycle_t)get_rtc();
}
static cycle_t timebase_read(struct clocksource *cs)
{
return (cycle_t)get_tb();
}
void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
struct clocksource *clock, u32 mult)
{
u64 new_tb_to_xs, new_stamp_xsec;
u32 frac_sec;
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 */
new_tb_to_xs = (u64) mult * 4611686018ULL;
new_stamp_xsec = (u64) wall_time->tv_nsec * XSEC_PER_SEC;
do_div(new_stamp_xsec, 1000000000);
new_stamp_xsec += (u64) wall_time->tv_sec * XSEC_PER_SEC;
BUG_ON(wall_time->tv_nsec >= NSEC_PER_SEC);
/* this is tv_nsec / 1e9 as a 0.32 fraction */
frac_sec = ((u64) wall_time->tv_nsec * 18446744073ULL) >> 32;
/*
* tb_update_count is used to allow the userspace gettimeofday code
* to assure itself that it sees a consistent view of the tb_to_xs and
* stamp_xsec variables. It reads the tb_update_count, then reads
* tb_to_xs and stamp_xsec and then reads tb_update_count again. If
* the two values of tb_update_count match and are even then the
* tb_to_xs and stamp_xsec values are consistent. If not, then it
* loops back and reads them again until this criteria is met.
* We expect the caller to have done the first increment of
* vdso_data->tb_update_count already.
*/
vdso_data->tb_orig_stamp = clock->cycle_last;
vdso_data->stamp_xsec = new_stamp_xsec;
vdso_data->tb_to_xs = new_tb_to_xs;
vdso_data->wtom_clock_sec = wtm->tv_sec;
vdso_data->wtom_clock_nsec = wtm->tv_nsec;
vdso_data->stamp_xtime = *wall_time;
vdso_data->stamp_sec_fraction = frac_sec;
smp_wmb();
++(vdso_data->tb_update_count);
}
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;
}
static 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);
}
static int decrementer_set_next_event(unsigned long evt,
struct clock_event_device *dev)
{
__get_cpu_var(decrementers).next_tb = get_tb_or_rtc() + evt;
set_dec(evt);
return 0;
}
static void decrementer_set_mode(enum clock_event_mode mode,
struct clock_event_device *dev)
{
if (mode != CLOCK_EVT_MODE_ONESHOT)
decrementer_set_next_event(DECREMENTER_MAX, dev);
}
static inline uint64_t div_sc64(unsigned long ticks, unsigned long nsec,
int shift)
{
uint64_t tmp = ((uint64_t)ticks) << shift;
do_div(tmp, nsec);
return tmp;
}
static void __init setup_clockevent_multiplier(unsigned long hz)
{
u64 mult, shift = 32;
while (1) {
mult = div_sc64(hz, NSEC_PER_SEC, shift);
if (mult && (mult >> 32UL) == 0UL)
break;
shift--;
}
decrementer_clockevent.shift = shift;
decrementer_clockevent.mult = mult;
}
static void register_decrementer_clockevent(int cpu)
{
struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;
*dec = decrementer_clockevent;
dec->cpumask = cpumask_of(cpu);
printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
dec->name, dec->mult, dec->shift, cpu);
clockevents_register_device(dec);
}
static void __init init_decrementer_clockevent(void)
{
int cpu = smp_processor_id();
setup_clockevent_multiplier(ppc_tb_freq);
decrementer_clockevent.max_delta_ns =
clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
decrementer_clockevent.min_delta_ns =
clockevent_delta2ns(2, &decrementer_clockevent);
register_decrementer_clockevent(cpu);
}
void secondary_cpu_time_init(void)
{
/* Start the decrementer on CPUs that have manual control
* such as BookE
*/
start_cpu_decrementer();
/* FIME: Should make unrelatred change to move snapshot_timebase
* call here ! */
register_decrementer_clockevent(smp_processor_id());
}
/* This function is only called on the boot processor */
void __init time_init(void)
{
struct div_result res;
u64 scale;
unsigned shift;
if (__USE_RTC()) {
/* 601 processor: dec counts down by 128 every 128ns */
ppc_tb_freq = 1000000000;
} else {
/* Normal PowerPC with timebase register */
ppc_md.calibrate_decr();
printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
}
tb_ticks_per_jiffy = ppc_tb_freq / HZ;
tb_ticks_per_sec = ppc_tb_freq;
tb_ticks_per_usec = ppc_tb_freq / 1000000;
calc_cputime_factors();
setup_cputime_one_jiffy();
/*
* Compute scale factor for sched_clock.
* The calibrate_decr() function has set tb_ticks_per_sec,
* which is the timebase frequency.
* We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
* the 128-bit result as a 64.64 fixed-point number.
* We then shift that number right until it is less than 1.0,
* giving us the scale factor and shift count to use in
* sched_clock().
*/
div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
scale = res.result_low;
for (shift = 0; res.result_high != 0; ++shift) {
scale = (scale >> 1) | (res.result_high << 63);
res.result_high >>= 1;
}
tb_to_ns_scale = scale;
tb_to_ns_shift = shift;
/* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
boot_tb = get_tb_or_rtc();
/* If platform provided a timezone (pmac), we correct the time */
if (timezone_offset) {
sys_tz.tz_minuteswest = -timezone_offset / 60;
sys_tz.tz_dsttime = 0;
}
vdso_data->tb_update_count = 0;
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
/* Start the decrementer on CPUs that have manual control
* such as BookE
*/
start_cpu_decrementer();
/* Register the clocksource, if we're not running on iSeries */
if (!firmware_has_feature(FW_FEATURE_ISERIES))
clocksource_init();
init_decrementer_clockevent();
}
#define FEBRUARY 2
#define STARTOFTIME 1970
#define SECDAY 86400L
#define SECYR (SECDAY * 365)
#define leapyear(year) ((year) % 4 == 0 && \
((year) % 100 != 0 || (year) % 400 == 0))
#define days_in_year(a) (leapyear(a) ? 366 : 365)
#define days_in_month(a) (month_days[(a) - 1])
static int month_days[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
/*
* This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
*/
void GregorianDay(struct rtc_time * tm)
{
int leapsToDate;
int lastYear;
int day;
int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
lastYear = tm->tm_year - 1;
/*
* Number of leap corrections to apply up to end of last year
*/
leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
/*
* This year is a leap year if it is divisible by 4 except when it is
* divisible by 100 unless it is divisible by 400
*
* e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
*/
day = tm->tm_mon > 2 && leapyear(tm->tm_year);
day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
tm->tm_mday;
tm->tm_wday = day % 7;
}
void to_tm(int tim, struct rtc_time * tm)
{
register int i;
register long hms, day;
day = tim / SECDAY;
hms = tim % SECDAY;
/* Hours, minutes, seconds are easy */
tm->tm_hour = hms / 3600;
tm->tm_min = (hms % 3600) / 60;
tm->tm_sec = (hms % 3600) % 60;
/* Number of years in days */
for (i = STARTOFTIME; day >= days_in_year(i); i++)
day -= days_in_year(i);
tm->tm_year = i;
/* Number of months in days left */
if (leapyear(tm->tm_year))
days_in_month(FEBRUARY) = 29;
for (i = 1; day >= days_in_month(i); i++)
day -= days_in_month(i);
days_in_month(FEBRUARY) = 28;
tm->tm_mon = i;
/* Days are what is left over (+1) from all that. */
tm->tm_mday = day + 1;
/*
* Determine the day of week
*/
GregorianDay(tm);
}
/*
* Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
* result.
*/
void div128_by_32(u64 dividend_high, u64 dividend_low,
unsigned divisor, struct div_result *dr)
{
unsigned long a, b, c, d;
unsigned long w, x, y, z;
u64 ra, rb, rc;
a = dividend_high >> 32;
b = dividend_high & 0xffffffff;
c = dividend_low >> 32;
d = dividend_low & 0xffffffff;
w = a / divisor;
ra = ((u64)(a - (w * divisor)) << 32) + b;
rb = ((u64) do_div(ra, divisor) << 32) + c;
x = ra;
rc = ((u64) do_div(rb, divisor) << 32) + d;
y = rb;
do_div(rc, divisor);
z = rc;
dr->result_high = ((u64)w << 32) + x;
dr->result_low = ((u64)y << 32) + z;
}
/* We don't need to calibrate delay, we use the CPU timebase for that */
void calibrate_delay(void)
{
/* Some generic code (such as spinlock debug) use loops_per_jiffy
* as the number of __delay(1) in a jiffy, so make it so
*/
loops_per_jiffy = tb_ticks_per_jiffy;
}
static int __init rtc_init(void)
{
struct platform_device *pdev;
if (!ppc_md.get_rtc_time)
return -ENODEV;
pdev = platform_device_register_simple("rtc-generic", -1, NULL, 0);
if (IS_ERR(pdev))
return PTR_ERR(pdev);
return 0;
}
module_init(rtc_init);
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