s390/time: refactor clock sync
Merge clock_sync_cpu into stp_sync_clock and split out the update of the global and per-CPU clock fields into clock_sync_global and clock_sync_local. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -52,11 +52,9 @@ static inline void store_clock_comparator(__u64 *time)
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void clock_comparator_work(void);
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void __init ptff_init(void);
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void __init time_early_init(void);
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extern unsigned char ptff_function_mask[16];
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extern unsigned long lpar_offset;
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extern unsigned long initial_leap_seconds;
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/* Function codes for the ptff instruction. */
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#define PTFF_QAF 0x00 /* query available functions */
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@ -467,7 +467,7 @@ void __init startup_init(void)
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ipl_save_parameters();
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rescue_initrd();
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clear_bss_section();
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ptff_init();
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time_early_init();
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init_kernel_storage_key();
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lockdep_off();
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setup_lowcore_early();
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@ -59,13 +59,14 @@ ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
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EXPORT_SYMBOL(s390_epoch_delta_notifier);
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unsigned char ptff_function_mask[16];
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unsigned long lpar_offset;
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unsigned long initial_leap_seconds;
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static unsigned long long lpar_offset;
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static unsigned long long initial_leap_seconds;
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/*
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* Get time offsets with PTFF
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*/
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void __init ptff_init(void)
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void __init time_early_init(void)
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{
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struct ptff_qto qto;
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struct ptff_qui qui;
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@ -80,7 +81,7 @@ void __init ptff_init(void)
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/* get initial leap seconds */
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if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
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initial_leap_seconds = (unsigned long)
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initial_leap_seconds = (unsigned long long)
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((long) qui.old_leap * 4096000000L);
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}
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@ -123,18 +124,6 @@ void clock_comparator_work(void)
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cd->event_handler(cd);
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}
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/*
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* Fixup the clock comparator.
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*/
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static void fixup_clock_comparator(unsigned long long delta)
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{
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/* If nobody is waiting there's nothing to fix. */
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if (S390_lowcore.clock_comparator == -1ULL)
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return;
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S390_lowcore.clock_comparator += delta;
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set_clock_comparator(S390_lowcore.clock_comparator);
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}
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static int s390_next_event(unsigned long delta,
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struct clock_event_device *evt)
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{
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@ -384,6 +373,36 @@ static inline int check_sync_clock(void)
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return rc;
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}
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/*
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* Apply clock delta to the global data structures.
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* This is called once on the CPU that performed the clock sync.
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*/
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static void clock_sync_global(unsigned long long delta)
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{
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struct ptff_qto qto;
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/* Fixup the monotonic sched clock. */
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sched_clock_base_cc += delta;
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/* Update LPAR offset. */
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if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
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lpar_offset = qto.tod_epoch_difference;
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/* Call the TOD clock change notifier. */
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atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);
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}
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/*
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* Apply clock delta to the per-CPU data structures of this CPU.
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* This is called for each online CPU after the call to clock_sync_global.
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*/
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static void clock_sync_local(unsigned long long delta)
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{
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/* Add the delta to the clock comparator. */
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if (S390_lowcore.clock_comparator != -1ULL) {
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S390_lowcore.clock_comparator += delta;
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set_clock_comparator(S390_lowcore.clock_comparator);
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}
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}
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/* Single threaded workqueue used for stp sync events */
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static struct workqueue_struct *time_sync_wq;
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@ -397,31 +416,9 @@ static void __init time_init_wq(void)
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struct clock_sync_data {
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atomic_t cpus;
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int in_sync;
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unsigned long long fixup_cc;
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unsigned long long clock_delta;
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};
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static void clock_sync_cpu(struct clock_sync_data *sync)
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{
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atomic_dec(&sync->cpus);
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enable_sync_clock();
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while (sync->in_sync == 0) {
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__udelay(1);
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/*
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* A different cpu changes *in_sync. Therefore use
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* barrier() to force memory access.
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*/
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barrier();
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}
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if (sync->in_sync != 1)
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/* Didn't work. Clear per-cpu in sync bit again. */
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disable_sync_clock(NULL);
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/*
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* This round of TOD syncing is done. Set the clock comparator
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* to the next tick and let the processor continue.
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*/
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fixup_clock_comparator(sync->fixup_cc);
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}
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/*
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* Server Time Protocol (STP) code.
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*/
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@ -523,54 +520,46 @@ void stp_queue_work(void)
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static int stp_sync_clock(void *data)
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{
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static int first;
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struct clock_sync_data *sync = data;
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unsigned long long clock_delta;
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struct clock_sync_data *stp_sync;
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struct ptff_qto qto;
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static int first;
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int rc;
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stp_sync = data;
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if (xchg(&first, 1) == 1) {
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/* Slave */
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clock_sync_cpu(stp_sync);
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return 0;
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}
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/* Wait until all other cpus entered the sync function. */
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while (atomic_read(&stp_sync->cpus) != 0)
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cpu_relax();
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enable_sync_clock();
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rc = 0;
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if (stp_info.todoff[0] || stp_info.todoff[1] ||
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stp_info.todoff[2] || stp_info.todoff[3] ||
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stp_info.tmd != 2) {
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rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0, &clock_delta);
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if (rc == 0) {
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/* fixup the monotonic sched clock */
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sched_clock_base_cc += clock_delta;
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if (ptff_query(PTFF_QTO) &&
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ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
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/* Update LPAR offset */
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lpar_offset = qto.tod_epoch_difference;
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atomic_notifier_call_chain(&s390_epoch_delta_notifier,
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0, &clock_delta);
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stp_sync->fixup_cc = clock_delta;
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fixup_clock_comparator(clock_delta);
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rc = chsc_sstpi(stp_page, &stp_info,
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sizeof(struct stp_sstpi));
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if (rc == 0 && stp_info.tmd != 2)
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rc = -EAGAIN;
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if (xchg(&first, 1) == 0) {
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/* Wait until all other cpus entered the sync function. */
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while (atomic_read(&sync->cpus) != 0)
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cpu_relax();
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rc = 0;
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if (stp_info.todoff[0] || stp_info.todoff[1] ||
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stp_info.todoff[2] || stp_info.todoff[3] ||
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stp_info.tmd != 2) {
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rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
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&clock_delta);
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if (rc == 0) {
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sync->clock_delta = clock_delta;
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clock_sync_global(clock_delta);
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rc = chsc_sstpi(stp_page, &stp_info,
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sizeof(struct stp_sstpi));
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if (rc == 0 && stp_info.tmd != 2)
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rc = -EAGAIN;
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}
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}
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sync->in_sync = rc ? -EAGAIN : 1;
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xchg(&first, 0);
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} else {
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/* Slave */
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atomic_dec(&sync->cpus);
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/* Wait for in_sync to be set. */
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while (READ_ONCE(sync->in_sync) == 0)
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__udelay(1);
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}
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if (rc) {
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if (sync->in_sync != 1)
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/* Didn't work. Clear per-cpu in sync bit again. */
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disable_sync_clock(NULL);
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stp_sync->in_sync = -EAGAIN;
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} else
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stp_sync->in_sync = 1;
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xchg(&first, 0);
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/* Apply clock delta to per-CPU fields of this CPU. */
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clock_sync_local(sync->clock_delta);
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return 0;
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}
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