diff options
| -rw-r--r-- | arch/s390/kernel/time.c | 212 |
1 files changed, 131 insertions, 81 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index b73bbf31f432..6e09bc285ba0 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -20,6 +20,8 @@ #include <linux/string.h> #include <linux/mm.h> #include <linux/interrupt.h> +#include <linux/cpu.h> +#include <linux/stop_machine.h> #include <linux/time.h> #include <linux/sysdev.h> #include <linux/delay.h> @@ -391,6 +393,15 @@ static void enable_sync_clock(void) atomic_set_mask(0x80000000, sw_ptr); } +/* Single threaded workqueue used for etr and stp sync events */ +static struct workqueue_struct *time_sync_wq; + +static void __init time_init_wq(void) +{ + if (!time_sync_wq) + time_sync_wq = create_singlethread_workqueue("timesync"); +} + /* * External Time Reference (ETR) code. */ @@ -483,17 +494,18 @@ static int __init etr_init(void) if (!test_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags)) return 0; + time_init_wq(); /* Check if this machine has the steai instruction. */ if (etr_steai(&aib, ETR_STEAI_STEPPING_PORT) == 0) etr_steai_available = 1; setup_timer(&etr_timer, etr_timeout, 0UL); if (etr_port0_online) { set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } if (etr_port1_online) { set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } return 0; } @@ -520,7 +532,7 @@ void etr_switch_to_local(void) if (test_bit(CLOCK_SYNC_ETR, &clock_sync_flags)) disable_sync_clock(NULL); set_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } /* @@ -536,7 +548,7 @@ void etr_sync_check(void) if (test_bit(CLOCK_SYNC_ETR, &clock_sync_flags)) disable_sync_clock(NULL); set_bit(ETR_EVENT_SYNC_CHECK, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } /* @@ -560,13 +572,13 @@ static void etr_timing_alert(struct etr_irq_parm *intparm) * Both ports are not up-to-date now. */ set_bit(ETR_EVENT_PORT_ALERT, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } static void etr_timeout(unsigned long dummy) { set_bit(ETR_EVENT_UPDATE, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } /* @@ -673,14 +685,16 @@ static int etr_aib_follows(struct etr_aib *a1, struct etr_aib *a2, int p) } struct clock_sync_data { + atomic_t cpus; int in_sync; unsigned long long fixup_cc; + int etr_port; + struct etr_aib *etr_aib; }; -static void clock_sync_cpu_start(void *dummy) +static void clock_sync_cpu(struct clock_sync_data *sync) { - struct clock_sync_data *sync = dummy; - + atomic_dec(&sync->cpus); enable_sync_clock(); /* * This looks like a busy wait loop but it isn't. etr_sync_cpus @@ -706,39 +720,35 @@ static void clock_sync_cpu_start(void *dummy) fixup_clock_comparator(sync->fixup_cc); } -static void clock_sync_cpu_end(void *dummy) -{ -} - /* * Sync the TOD clock using the port refered to by aibp. This port * has to be enabled and the other port has to be disabled. The * last eacr update has to be more than 1.6 seconds in the past. */ -static int etr_sync_clock(struct etr_aib *aib, int port) +static int etr_sync_clock(void *data) { - struct etr_aib *sync_port; - struct clock_sync_data etr_sync; + static int first; unsigned long long clock, old_clock, delay, delta; - int follows; + struct clock_sync_data *etr_sync; + struct etr_aib *sync_port, *aib; + int port; int rc; - /* Check if the current aib is adjacent to the sync port aib. */ - sync_port = (port == 0) ? &etr_port0 : &etr_port1; - follows = etr_aib_follows(sync_port, aib, port); - memcpy(sync_port, aib, sizeof(*aib)); - if (!follows) - return -EAGAIN; + etr_sync = data; - /* - * Catch all other cpus and make them wait until we have - * successfully synced the clock. smp_call_function will - * return after all other cpus are in etr_sync_cpu_start. - */ - memset(&etr_sync, 0, sizeof(etr_sync)); - preempt_disable(); - smp_call_function(clock_sync_cpu_start, &etr_sync, 0); - local_irq_disable(); + if (xchg(&first, 1) == 1) { + /* Slave */ + clock_sync_cpu(etr_sync); + return 0; + } + + /* Wait until all other cpus entered the sync function. */ + while (atomic_read(&etr_sync->cpus) != 0) + cpu_relax(); + + port = etr_sync->etr_port; + aib = etr_sync->etr_aib; + sync_port = (port == 0) ? &etr_port0 : &etr_port1; enable_sync_clock(); /* Set clock to next OTE. */ @@ -755,16 +765,16 @@ static int etr_sync_clock(struct etr_aib *aib, int port) delay = (unsigned long long) (aib->edf2.etv - sync_port->edf2.etv) << 32; delta = adjust_time(old_clock, clock, delay); - etr_sync.fixup_cc = delta; + etr_sync->fixup_cc = delta; fixup_clock_comparator(delta); /* Verify that the clock is properly set. */ if (!etr_aib_follows(sync_port, aib, port)) { /* Didn't work. */ disable_sync_clock(NULL); - etr_sync.in_sync = -EAGAIN; + etr_sync->in_sync = -EAGAIN; rc = -EAGAIN; } else { - etr_sync.in_sync = 1; + etr_sync->in_sync = 1; rc = 0; } } else { @@ -772,12 +782,33 @@ static int etr_sync_clock(struct etr_aib *aib, int port) __ctl_clear_bit(0, 29); __ctl_clear_bit(14, 21); disable_sync_clock(NULL); - etr_sync.in_sync = -EAGAIN; + etr_sync->in_sync = -EAGAIN; rc = -EAGAIN; } - local_irq_enable(); - smp_call_function(clock_sync_cpu_end, NULL, 0); - preempt_enable(); + xchg(&first, 0); + return rc; +} + +static int etr_sync_clock_stop(struct etr_aib *aib, int port) +{ + struct clock_sync_data etr_sync; + struct etr_aib *sync_port; + int follows; + int rc; + + /* Check if the current aib is adjacent to the sync port aib. */ + sync_port = (port == 0) ? &etr_port0 : &etr_port1; + follows = etr_aib_follows(sync_port, aib, port); + memcpy(sync_port, aib, sizeof(*aib)); + if (!follows) + return -EAGAIN; + memset(&etr_sync, 0, sizeof(etr_sync)); + etr_sync.etr_aib = aib; + etr_sync.etr_port = port; + get_online_cpus(); + atomic_set(&etr_sync.cpus, num_online_cpus() - 1); + rc = stop_machine(etr_sync_clock, &etr_sync, &cpu_online_map); + put_online_cpus(); return rc; } @@ -934,7 +965,7 @@ static void etr_update_eacr(struct etr_eacr eacr) } /* - * ETR tasklet. In this function you'll find the main logic. In + * ETR work. In this function you'll find the main logic. In * particular this is the only function that calls etr_update_eacr(), * it "controls" the etr control register. */ @@ -1067,7 +1098,7 @@ static void etr_work_fn(struct work_struct *work) etr_update_eacr(eacr); set_bit(CLOCK_SYNC_ETR, &clock_sync_flags); if (now < etr_tolec + (1600000 << 12) || - etr_sync_clock(&aib, sync_port) != 0) { + etr_sync_clock_stop(&aib, sync_port) != 0) { /* Sync failed. Try again in 1/2 second. */ eacr.es = 0; etr_update_eacr(eacr); @@ -1156,13 +1187,13 @@ static ssize_t etr_online_store(struct sys_device *dev, return count; /* Nothing to do. */ etr_port0_online = value; set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } else { if (etr_port1_online == value) return count; /* Nothing to do. */ etr_port1_online = value; set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events); - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } return count; } @@ -1396,8 +1427,12 @@ static void __init stp_reset(void) static int __init stp_init(void) { - if (test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags) && stp_online) - schedule_work(&stp_work); + if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags)) + return 0; + time_init_wq(); + if (!stp_online) + return 0; + queue_work(time_sync_wq, &stp_work); return 0; } @@ -1414,7 +1449,7 @@ arch_initcall(stp_init); static void stp_timing_alert(struct stp_irq_parm *intparm) { if (intparm->tsc || intparm->lac || intparm->tcpc) - schedule_work(&stp_work); + queue_work(time_sync_wq, &stp_work); } /* @@ -1428,7 +1463,7 @@ void stp_sync_check(void) if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags)) return; disable_sync_clock(NULL); - schedule_work(&stp_work); + queue_work(time_sync_wq, &stp_work); } /* @@ -1442,46 +1477,34 @@ void stp_island_check(void) if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags)) return; disable_sync_clock(NULL); - schedule_work(&stp_work); + queue_work(time_sync_wq, &stp_work); } -/* - * STP tasklet. Check for the STP state and take over the clock - * synchronization if the STP clock source is usable. - */ -static void stp_work_fn(struct work_struct *work) + +static int stp_sync_clock(void *data) { - struct clock_sync_data stp_sync; + static int first; unsigned long long old_clock, delta; + struct clock_sync_data *stp_sync; int rc; - if (!stp_online) { - chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000); - return; - } + stp_sync = data; - rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xb0e0); - if (rc) - return; + if (xchg(&first, 1) == 1) { + /* Slave */ + clock_sync_cpu(stp_sync); + return 0; + } - rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi)); - if (rc || stp_info.c == 0) - return; + /* Wait until all other cpus entered the sync function. */ + while (atomic_read(&stp_sync->cpus) != 0) + cpu_relax(); - /* - * Catch all other cpus and make them wait until we have - * successfully synced the clock. smp_call_function will - * return after all other cpus are in clock_sync_cpu_start. - */ - memset(&stp_sync, 0, sizeof(stp_sync)); - preempt_disable(); - smp_call_function(clock_sync_cpu_start, &stp_sync, 0); - local_irq_disable(); enable_sync_clock(); set_bit(CLOCK_SYNC_STP, &clock_sync_flags); if (test_and_clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags)) - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); rc = 0; if (stp_info.todoff[0] || stp_info.todoff[1] || @@ -1500,16 +1523,43 @@ static void stp_work_fn(struct work_struct *work) } if (rc) { disable_sync_clock(NULL); - stp_sync.in_sync = -EAGAIN; + stp_sync->in_sync = -EAGAIN; clear_bit(CLOCK_SYNC_STP, &clock_sync_flags); if (etr_port0_online || etr_port1_online) - schedule_work(&etr_work); + queue_work(time_sync_wq, &etr_work); } else - stp_sync.in_sync = 1; + stp_sync->in_sync = 1; + xchg(&first, 0); + return 0; +} - local_irq_enable(); - smp_call_function(clock_sync_cpu_end, NULL, 0); - preempt_enable(); +/* + * STP work. Check for the STP state and take over the clock + * synchronization if the STP clock source is usable. + */ +static void stp_work_fn(struct work_struct *work) +{ + struct clock_sync_data stp_sync; + int rc; + + if (!stp_online) { + chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000); + return; + } + + rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xb0e0); + if (rc) + return; + + rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi)); + if (rc || stp_info.c == 0) + return; + + memset(&stp_sync, 0, sizeof(stp_sync)); + get_online_cpus(); + atomic_set(&stp_sync.cpus, num_online_cpus() - 1); + stop_machine(stp_sync_clock, &stp_sync, &cpu_online_map); + put_online_cpus(); } /* @@ -1618,7 +1668,7 @@ static ssize_t stp_online_store(struct sysdev_class *class, if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags)) return -EOPNOTSUPP; stp_online = value; - schedule_work(&stp_work); + queue_work(time_sync_wq, &stp_work); return count; } |