Commit b1c0854d authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 62ba6f85

arch/s390/include/asm/timex.h

+1 −3
Original line number Diff line number Diff line
@@ -52,11 +52,9 @@ static inline void store_clock_comparator(__u64 *time) 


void clock_comparator_work(void);



void __init ptff_init(void);

void __init time_early_init(void);



extern unsigned char ptff_function_mask[16];

extern unsigned long lpar_offset;

extern unsigned long initial_leap_seconds;



/* Function codes for the ptff instruction. */

#define PTFF_QAF	0x00	/* query available functions */

arch/s390/kernel/early.c

+1 −1
Original line number Diff line number Diff line
@@ -467,7 +467,7 @@ void __init startup_init(void) 
	ipl_save_parameters();

	rescue_initrd();

	clear_bss_section();

	ptff_init();

	time_early_init();

	init_kernel_storage_key();

	lockdep_off();

	setup_lowcore_early();

arch/s390/kernel/time.c

+69 −80
Original line number Diff line number Diff line
@@ -59,13 +59,14 @@ ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier); 
EXPORT_SYMBOL(s390_epoch_delta_notifier);



unsigned char ptff_function_mask[16];

unsigned long lpar_offset;

unsigned long initial_leap_seconds;



static unsigned long long lpar_offset;

static unsigned long long initial_leap_seconds;



/*

 * Get time offsets with PTFF

 */

void __init ptff_init(void)

void __init time_early_init(void)

{

	struct ptff_qto qto;

	struct ptff_qui qui;
@@ -80,7 +81,7 @@ void __init ptff_init(void) 


	/* get initial leap seconds */

	if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)

		initial_leap_seconds = (unsigned long)

		initial_leap_seconds = (unsigned long long)

			((long) qui.old_leap * 4096000000L);

}
@@ -123,18 +124,6 @@ void clock_comparator_work(void) 
	cd->event_handler(cd);

}



/*

 * Fixup the clock comparator.

 */

static void fixup_clock_comparator(unsigned long long delta)

{

	/* If nobody is waiting there's nothing to fix. */

	if (S390_lowcore.clock_comparator == -1ULL)

		return;

	S390_lowcore.clock_comparator += delta;

	set_clock_comparator(S390_lowcore.clock_comparator);

}



static int s390_next_event(unsigned long delta,

			   struct clock_event_device *evt)

{
@@ -384,6 +373,36 @@ static inline int check_sync_clock(void) 
	return rc;

}



/*

 * Apply clock delta to the global data structures.

 * This is called once on the CPU that performed the clock sync.

 */

static void clock_sync_global(unsigned long long delta)

{

	struct ptff_qto qto;



	/* Fixup the monotonic sched clock. */

	sched_clock_base_cc += delta;

	/* Update LPAR offset. */

	if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)

		lpar_offset = qto.tod_epoch_difference;

	/* Call the TOD clock change notifier. */

	atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);

}



/*

 * Apply clock delta to the per-CPU data structures of this CPU.

 * This is called for each online CPU after the call to clock_sync_global.

 */

static void clock_sync_local(unsigned long long delta)

{

	/* Add the delta to the clock comparator. */

	if (S390_lowcore.clock_comparator != -1ULL) {

		S390_lowcore.clock_comparator += delta;

		set_clock_comparator(S390_lowcore.clock_comparator);

	}

}



/* Single threaded workqueue used for stp sync events */

static struct workqueue_struct *time_sync_wq;
@@ -397,31 +416,9 @@ static void __init time_init_wq(void) 
struct clock_sync_data {

	atomic_t cpus;

	int in_sync;

	unsigned long long fixup_cc;

	unsigned long long clock_delta;

};



static void clock_sync_cpu(struct clock_sync_data *sync)

{

	atomic_dec(&sync->cpus);

	enable_sync_clock();

	while (sync->in_sync == 0) {

		__udelay(1);

		/*

		 * A different cpu changes *in_sync. Therefore use

		 * barrier() to force memory access.

		 */

		barrier();

	}

	if (sync->in_sync != 1)

		/* Didn't work. Clear per-cpu in sync bit again. */

		disable_sync_clock(NULL);

	/*

	 * This round of TOD syncing is done. Set the clock comparator

	 * to the next tick and let the processor continue.

	 */

	fixup_clock_comparator(sync->fixup_cc);

}



/*

 * Server Time Protocol (STP) code.

 */
@@ -523,54 +520,46 @@ void stp_queue_work(void) 


static int stp_sync_clock(void *data)

{

	static int first;

	struct clock_sync_data *sync = data;

	unsigned long long clock_delta;

	struct clock_sync_data *stp_sync;

	struct ptff_qto qto;

	static int first;

	int rc;



	stp_sync = data;



	if (xchg(&first, 1) == 1) {

		/* Slave */

		clock_sync_cpu(stp_sync);

		return 0;

	}



	enable_sync_clock();

	if (xchg(&first, 1) == 0) {

		/* Wait until all other cpus entered the sync function. */

	while (atomic_read(&stp_sync->cpus) != 0)

		while (atomic_read(&sync->cpus) != 0)

			cpu_relax();



	enable_sync_clock();



		rc = 0;

		if (stp_info.todoff[0] || stp_info.todoff[1] ||

		    stp_info.todoff[2] || stp_info.todoff[3] ||

		    stp_info.tmd != 2) {

		rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0, &clock_delta);

			rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,

					&clock_delta);

			if (rc == 0) {

			/* fixup the monotonic sched clock */

			sched_clock_base_cc += clock_delta;

			if (ptff_query(PTFF_QTO) &&

			    ptff(&qto, sizeof(qto), PTFF_QTO) == 0)

				/* Update LPAR offset */

				lpar_offset = qto.tod_epoch_difference;

			atomic_notifier_call_chain(&s390_epoch_delta_notifier,

						   0, &clock_delta);

			stp_sync->fixup_cc = clock_delta;

			fixup_clock_comparator(clock_delta);

				sync->clock_delta = clock_delta;

				clock_sync_global(clock_delta);

				rc = chsc_sstpi(stp_page, &stp_info,

						sizeof(struct stp_sstpi));

				if (rc == 0 && stp_info.tmd != 2)

					rc = -EAGAIN;

			}

		}

	if (rc) {

		disable_sync_clock(NULL);

		stp_sync->in_sync = -EAGAIN;

	} else

		stp_sync->in_sync = 1;

		sync->in_sync = rc ? -EAGAIN : 1;

		xchg(&first, 0);

	} else {

		/* Slave */

		atomic_dec(&sync->cpus);

		/* Wait for in_sync to be set. */

		while (READ_ONCE(sync->in_sync) == 0)

			__udelay(1);

	}

	if (sync->in_sync != 1)

		/* Didn't work. Clear per-cpu in sync bit again. */

		disable_sync_clock(NULL);

	/* Apply clock delta to per-CPU fields of this CPU. */

	clock_sync_local(sync->clock_delta);



	return 0;

}