5 files changed, 582 insertions, 153 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 7aec676fefd5..7418bebb547f 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -3,7 +3,7 @@
  *    Time of day based timer functions.
  *
  *  S390 version
- *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    Copyright IBM Corp. 1999, 2008
  *    Author(s): Hartmut Penner (hp@de.ibm.com),
  *               Martin Schwidefsky (schwidefsky@de.ibm.com),
  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
@@ -31,6 +31,7 @@
 #include <linux/notifier.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
+#include <linux/bootmem.h>
 #include <asm/uaccess.h>
 #include <asm/delay.h>
 #include <asm/s390_ext.h>
@@ -162,7 +163,7 @@ void init_cpu_timer(void)
         /* Enable clock comparator timer interrupt. */
         __ctl_set_bit(0,11);
 
-        /* Always allow ETR external interrupts, even without an ETR. */
+        /* Always allow the timing alert external interrupt. */
         __ctl_set_bit(0, 4);
 }
 
@@ -170,8 +171,21 @@ static void clock_comparator_interrupt(__u16 code)
 {
 }
 
+static void etr_timing_alert(struct etr_irq_parm *);
+static void stp_timing_alert(struct stp_irq_parm *);
+
+static void timing_alert_interrupt(__u16 code)
+{
+        if (S390_lowcore.ext_params & 0x00c40000)
+                etr_timing_alert((struct etr_irq_parm *)
+                                 &S390_lowcore.ext_params);
+        if (S390_lowcore.ext_params & 0x00038000)
+                stp_timing_alert((struct stp_irq_parm *)
+                                 &S390_lowcore.ext_params);
+}
+
 static void etr_reset(void);
-static void etr_ext_handler(__u16);
+static void stp_reset(void);
 
 /*
  * Get the TOD clock running.
@@ -181,6 +195,7 @@ static u64 __init reset_tod_clock(void)
         u64 time;
 
         etr_reset();
+        stp_reset();
         if (store_clock(&time) == 0)
                 return time;
         /* TOD clock not running. Set the clock to Unix Epoch. */
@@ -231,8 +246,9 @@ void __init time_init(void)
         if (clocksource_register(&clocksource_tod) != 0)
                 panic("Could not register TOD clock source");
 
-        /* request the etr external interrupt */
-        if (register_early_external_interrupt(0x1406, etr_ext_handler,
+        /* request the timing alert external interrupt */
+        if (register_early_external_interrupt(0x1406,
+                                              timing_alert_interrupt,
                                               &ext_int_etr_cc) != 0)
                 panic("Couldn't request external interrupt 0x1406");
 
@@ -245,10 +261,112 @@ void __init time_init(void)
 }
 
 /*
+ * The time is "clock". old is what we think the time is.
+ * Adjust the value by a multiple of jiffies and add the delta to ntp.
+ * "delay" is an approximation how long the synchronization took. If
+ * the time correction is positive, then "delay" is subtracted from
+ * the time difference and only the remaining part is passed to ntp.
+ */
+static unsigned long long adjust_time(unsigned long long old,
+                                      unsigned long long clock,
+                                      unsigned long long delay)
+{
+        unsigned long long delta, ticks;
+        struct timex adjust;
+
+        if (clock > old) {
+                /* It is later than we thought. */
+                delta = ticks = clock - old;
+                delta = ticks = (delta < delay) ? 0 : delta - delay;
+                delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
+                adjust.offset = ticks * (1000000 / HZ);
+        } else {
+                /* It is earlier than we thought. */
+                delta = ticks = old - clock;
+                delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
+                delta = -delta;
+                adjust.offset = -ticks * (1000000 / HZ);
+        }
+        jiffies_timer_cc += delta;
+        if (adjust.offset != 0) {
+                printk(KERN_NOTICE "etr: time adjusted by %li micro-seconds\n",
+                       adjust.offset);
+                adjust.modes = ADJ_OFFSET_SINGLESHOT;
+                do_adjtimex(&adjust);
+        }
+        return delta;
+}
+
+static DEFINE_PER_CPU(atomic_t, clock_sync_word);
+static unsigned long clock_sync_flags;
+
+#define CLOCK_SYNC_HAS_ETR      0
+#define CLOCK_SYNC_HAS_STP      1
+#define CLOCK_SYNC_ETR          2
+#define CLOCK_SYNC_STP          3
+
+/*
+ * The synchronous get_clock function. It will write the current clock
+ * value to the clock pointer and return 0 if the clock is in sync with
+ * the external time source. If the clock mode is local it will return
+ * -ENOSYS and -EAGAIN if the clock is not in sync with the external
+ * reference.
+ */
+int get_sync_clock(unsigned long long *clock)
+{
+        atomic_t *sw_ptr;
+        unsigned int sw0, sw1;
+
+        sw_ptr = &get_cpu_var(clock_sync_word);
+        sw0 = atomic_read(sw_ptr);
+        *clock = get_clock();
+        sw1 = atomic_read(sw_ptr);
+        put_cpu_var(clock_sync_sync);
+        if (sw0 == sw1 && (sw0 & 0x80000000U))
+                /* Success: time is in sync. */
+                return 0;
+        if (!test_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags) &&
+            !test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
+                return -ENOSYS;
+        if (!test_bit(CLOCK_SYNC_ETR, &clock_sync_flags) &&
+            !test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
+                return -EACCES;
+        return -EAGAIN;
+}
+EXPORT_SYMBOL(get_sync_clock);
+
+/*
+ * Make get_sync_clock return -EAGAIN.
+ */
+static void disable_sync_clock(void *dummy)
+{
+        atomic_t *sw_ptr = &__get_cpu_var(clock_sync_word);
+        /*
+         * Clear the in-sync bit 2^31. All get_sync_clock calls will
+         * fail until the sync bit is turned back on. In addition
+         * increase the "sequence" counter to avoid the race of an
+         * etr event and the complete recovery against get_sync_clock.
+         */
+        atomic_clear_mask(0x80000000, sw_ptr);
+        atomic_inc(sw_ptr);
+}
+
+/*
+ * Make get_sync_clock return 0 again.
+ * Needs to be called from a context disabled for preemption.
+ */
+static void enable_sync_clock(void)
+{
+        atomic_t *sw_ptr = &__get_cpu_var(clock_sync_word);
+        atomic_set_mask(0x80000000, sw_ptr);
+}
+
+/*
  * External Time Reference (ETR) code.
  */
 static int etr_port0_online;
 static int etr_port1_online;
+static int etr_steai_available;
 
 static int __init early_parse_etr(char *p)
 {
@@ -273,12 +391,6 @@ enum etr_event {
         ETR_EVENT_UPDATE,
 };
 
-enum etr_flags {
-        ETR_FLAG_ENOSYS,
-        ETR_FLAG_EACCES,
-        ETR_FLAG_STEAI,
-};
-
 /*
  * Valid bit combinations of the eacr register are (x = don't care):
  * e0 e1 dp p0 p1 ea es sl
@@ -305,74 +417,18 @@ enum etr_flags {
  */
 static struct etr_eacr etr_eacr;
 static u64 etr_tolec;                   /* time of last eacr update */
-static unsigned long etr_flags;
 static struct etr_aib etr_port0;
 static int etr_port0_uptodate;
 static struct etr_aib etr_port1;
 static int etr_port1_uptodate;
 static unsigned long etr_events;
 static struct timer_list etr_timer;
-static DEFINE_PER_CPU(atomic_t, etr_sync_word);
 
 static void etr_timeout(unsigned long dummy);
 static void etr_work_fn(struct work_struct *work);
 static DECLARE_WORK(etr_work, etr_work_fn);
 
 /*
- * The etr get_clock function. It will write the current clock value
- * to the clock pointer and return 0 if the clock is in sync with the
- * external time source. If the clock mode is local it will return
- * -ENOSYS and -EAGAIN if the clock is not in sync with the external
- * reference. This function is what ETR is all about..
- */
-int get_sync_clock(unsigned long long *clock)
-{
-        atomic_t *sw_ptr;
-        unsigned int sw0, sw1;
-
-        sw_ptr = &get_cpu_var(etr_sync_word);
-        sw0 = atomic_read(sw_ptr);
-        *clock = get_clock();
-        sw1 = atomic_read(sw_ptr);
-        put_cpu_var(etr_sync_sync);
-        if (sw0 == sw1 && (sw0 & 0x80000000U))
-                /* Success: time is in sync. */
-                return 0;
-        if (test_bit(ETR_FLAG_ENOSYS, &etr_flags))
-                return -ENOSYS;
-        if (test_bit(ETR_FLAG_EACCES, &etr_flags))
-                return -EACCES;
-        return -EAGAIN;
-}
-EXPORT_SYMBOL(get_sync_clock);
-
-/*
- * Make get_sync_clock return -EAGAIN.
- */
-static void etr_disable_sync_clock(void *dummy)
-{
-        atomic_t *sw_ptr = &__get_cpu_var(etr_sync_word);
-        /*
-         * Clear the in-sync bit 2^31. All get_sync_clock calls will
-         * fail until the sync bit is turned back on. In addition
-         * increase the "sequence" counter to avoid the race of an
-         * etr event and the complete recovery against get_sync_clock.
-         */
-        atomic_clear_mask(0x80000000, sw_ptr);
-        atomic_inc(sw_ptr);
-}
-
-/*
- * Make get_sync_clock return 0 again.
- * Needs to be called from a context disabled for preemption.
- */
-static void etr_enable_sync_clock(void)
-{
-        atomic_t *sw_ptr = &__get_cpu_var(etr_sync_word);
-        atomic_set_mask(0x80000000, sw_ptr);
-}
-
-/*
  * Reset ETR attachment.
  */
 static void etr_reset(void)
@@ -381,15 +437,13 @@ static void etr_reset(void)
                 .e0 = 0, .e1 = 0, ._pad0 = 4, .dp = 0,
                 .p0 = 0, .p1 = 0, ._pad1 = 0, .ea = 0,
                 .es = 0, .sl = 0 };
-        if (etr_setr(&etr_eacr) == 0)
+        if (etr_setr(&etr_eacr) == 0) {
                 etr_tolec = get_clock();
-        else {
-                set_bit(ETR_FLAG_ENOSYS, &etr_flags);
-                if (etr_port0_online || etr_port1_online) {
-                        printk(KERN_WARNING "Running on non ETR capable "
-                               "machine, only local mode available.\n");
-                        etr_port0_online = etr_port1_online = 0;
-                }
+                set_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags);
+        } else if (etr_port0_online || etr_port1_online) {
+                printk(KERN_WARNING "Running on non ETR capable "
+                       "machine, only local mode available.\n");
+                etr_port0_online = etr_port1_online = 0;
         }
 }
 
@@ -397,14 +451,12 @@ static int __init etr_init(void)
 {
         struct etr_aib aib;
 
-        if (test_bit(ETR_FLAG_ENOSYS, &etr_flags))
+        if (!test_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags))
                 return 0;
         /* Check if this machine has the steai instruction. */
         if (etr_steai(&aib, ETR_STEAI_STEPPING_PORT) == 0)
-                set_bit(ETR_FLAG_STEAI, &etr_flags);
+                etr_steai_available = 1;
         setup_timer(&etr_timer, etr_timeout, 0UL);
-        if (!etr_port0_online && !etr_port1_online)
-                set_bit(ETR_FLAG_EACCES, &etr_flags);
         if (etr_port0_online) {
                 set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events);
                 schedule_work(&etr_work);
@@ -435,7 +487,8 @@ void etr_switch_to_local(void)
 {
         if (!etr_eacr.sl)
                 return;
-        etr_disable_sync_clock(NULL);
+        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);
 }
@@ -450,23 +503,21 @@ void etr_sync_check(void)
 {
         if (!etr_eacr.es)
                 return;
-        etr_disable_sync_clock(NULL);
+        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);
 }
 
 /*
- * ETR external interrupt. There are two causes:
+ * ETR timing alert. There are two causes:
  * 1) port state change, check the usability of the port
  * 2) port alert, one of the ETR-data-validity bits (v1-v2 bits of the
  *    sldr-status word) or ETR-data word 1 (edf1) or ETR-data word 3 (edf3)
  *    or ETR-data word 4 (edf4) has changed.
  */
-static void etr_ext_handler(__u16 code)
+static void etr_timing_alert(struct etr_irq_parm *intparm)
 {
-        struct etr_interruption_parameter *intparm =
-                (struct etr_interruption_parameter *) &S390_lowcore.ext_params;
-
         if (intparm->pc0)
                 /* ETR port 0 state change. */
                 set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events);
@@ -591,58 +642,23 @@ static int etr_aib_follows(struct etr_aib *a1, struct etr_aib *a2, int p)
         return 1;
 }
 
-/*
- * The time is "clock". old is what we think the time is.
- * Adjust the value by a multiple of jiffies and add the delta to ntp.
- * "delay" is an approximation how long the synchronization took. If
- * the time correction is positive, then "delay" is subtracted from
- * the time difference and only the remaining part is passed to ntp.
- */
-static unsigned long long etr_adjust_time(unsigned long long old,
-                                          unsigned long long clock,
-                                          unsigned long long delay)
-{
-        unsigned long long delta, ticks;
-        struct timex adjust;
-
-        if (clock > old) {
-                /* It is later than we thought. */
-                delta = ticks = clock - old;
-                delta = ticks = (delta < delay) ? 0 : delta - delay;
-                delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
-                adjust.offset = ticks * (1000000 / HZ);
-        } else {
-                /* It is earlier than we thought. */
-                delta = ticks = old - clock;
-                delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
-                delta = -delta;
-                adjust.offset = -ticks * (1000000 / HZ);
-        }
-        jiffies_timer_cc += delta;
-        if (adjust.offset != 0) {
-                printk(KERN_NOTICE "etr: time adjusted by %li micro-seconds\n",
-                       adjust.offset);
-                adjust.modes = ADJ_OFFSET_SINGLESHOT;
-                do_adjtimex(&adjust);
-        }
-        return delta;
-}
-
-static struct {
+struct clock_sync_data {
         int in_sync;
         unsigned long long fixup_cc;
-} etr_sync;
+};
 
-static void etr_sync_cpu_start(void *dummy)
+static void clock_sync_cpu_start(void *dummy)
 {
-        etr_enable_sync_clock();
+        struct clock_sync_data *sync = dummy;
+
+        enable_sync_clock();
         /*
          * This looks like a busy wait loop but it isn't. etr_sync_cpus
          * is called on all other cpus while the TOD clocks is stopped.
          * __udelay will stop the cpu on an enabled wait psw until the
          * TOD is running again.
          */
-        while (etr_sync.in_sync == 0) {
+        while (sync->in_sync == 0) {
                 __udelay(1);
                 /*
                  * A different cpu changes *in_sync. Therefore use
@@ -650,17 +666,17 @@ static void etr_sync_cpu_start(void *dummy)
                  */
                 barrier();
         }
-        if (etr_sync.in_sync != 1)
+        if (sync->in_sync != 1)
                 /* Didn't work. Clear per-cpu in sync bit again. */
-                etr_disable_sync_clock(NULL);
+                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(etr_sync.fixup_cc);
+        fixup_clock_comparator(sync->fixup_cc);
 }
 
-static void etr_sync_cpu_end(void *dummy)
+static void clock_sync_cpu_end(void *dummy)
 {
 }
 
@@ -672,6 +688,7 @@ static void etr_sync_cpu_end(void *dummy)
 static int etr_sync_clock(struct etr_aib *aib, int port)
 {
         struct etr_aib *sync_port;
+        struct clock_sync_data etr_sync;
         unsigned long long clock, old_clock, delay, delta;
         int follows;
         int rc;
@@ -690,9 +707,9 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
          */
         memset(&etr_sync, 0, sizeof(etr_sync));
         preempt_disable();
-        smp_call_function(etr_sync_cpu_start, NULL, 0, 0);
+        smp_call_function(clock_sync_cpu_start, &etr_sync, 0, 0);
         local_irq_disable();
-        etr_enable_sync_clock();
+        enable_sync_clock();
 
         /* Set clock to next OTE. */
         __ctl_set_bit(14, 21);
@@ -707,13 +724,13 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
                 /* Adjust Linux timing variables. */
                 delay = (unsigned long long)
                         (aib->edf2.etv - sync_port->edf2.etv) << 32;
-                delta = etr_adjust_time(old_clock, clock, delay);
+                delta = adjust_time(old_clock, clock, delay);
                 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. */
-                        etr_disable_sync_clock(NULL);
+                        disable_sync_clock(NULL);
                         etr_sync.in_sync = -EAGAIN;
                         rc = -EAGAIN;
                 } else {
@@ -724,12 +741,12 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
                 /* Could not set the clock ?!? */
                 __ctl_clear_bit(0, 29);
                 __ctl_clear_bit(14, 21);
-                etr_disable_sync_clock(NULL);
+                disable_sync_clock(NULL);
                 etr_sync.in_sync = -EAGAIN;
                 rc = -EAGAIN;
         }
         local_irq_enable();
-        smp_call_function(etr_sync_cpu_end,NULL,0,0);
+        smp_call_function(clock_sync_cpu_end, NULL, 0, 0);
         preempt_enable();
         return rc;
 }
@@ -832,7 +849,7 @@ static struct etr_eacr etr_handle_update(struct etr_aib *aib,
          * Do not try to get the alternate port aib if the clock
          * is not in sync yet.
          */
-        if (!eacr.es)
+        if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags) && !eacr.es)
                 return eacr;
 
         /*
@@ -840,7 +857,7 @@ static struct etr_eacr etr_handle_update(struct etr_aib *aib,
          * the other port immediately. If only stetr is available the
          * data-port bit toggle has to be used.
          */
-        if (test_bit(ETR_FLAG_STEAI, &etr_flags)) {
+        if (etr_steai_available) {
                 if (eacr.p0 && !etr_port0_uptodate) {
                         etr_steai_cv(&etr_port0, ETR_STEAI_PORT_0);
                         etr_port0_uptodate = 1;
@@ -909,10 +926,10 @@ static void etr_work_fn(struct work_struct *work)
         if (!eacr.ea) {
                 /* Both ports offline. Reset everything. */
                 eacr.dp = eacr.es = eacr.sl = 0;
-                on_each_cpu(etr_disable_sync_clock, NULL, 0, 1);
+                on_each_cpu(disable_sync_clock, NULL, 0, 1);
                 del_timer_sync(&etr_timer);
                 etr_update_eacr(eacr);
-                set_bit(ETR_FLAG_EACCES, &etr_flags);
+                clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);
                 return;
         }
 
@@ -953,7 +970,6 @@ static void etr_work_fn(struct work_struct *work)
                         eacr.e1 = 1;
                 sync_port = (etr_port0_uptodate &&
                              etr_port_valid(&etr_port0, 0)) ? 0 : -1;
-                clear_bit(ETR_FLAG_EACCES, &etr_flags);
         } else if (eacr.p1 && aib.esw.psc1 == etr_lpsc_pps_mode) {
                 eacr.sl = 0;
                 eacr.e0 = 0;
@@ -962,7 +978,6 @@ static void etr_work_fn(struct work_struct *work)
                         eacr.es = 0;
                 sync_port = (etr_port1_uptodate &&
                              etr_port_valid(&etr_port1, 1)) ? 1 : -1;
-                clear_bit(ETR_FLAG_EACCES, &etr_flags);
         } else if (eacr.p0 && aib.esw.psc0 == etr_lpsc_operational_step) {
                 eacr.sl = 1;
                 eacr.e0 = 1;
@@ -976,7 +991,6 @@ static void etr_work_fn(struct work_struct *work)
                         eacr.e1 = 1;
                 sync_port = (etr_port0_uptodate &&
                              etr_port_valid(&etr_port0, 0)) ? 0 : -1;
-                clear_bit(ETR_FLAG_EACCES, &etr_flags);
         } else if (eacr.p1 && aib.esw.psc1 == etr_lpsc_operational_step) {
                 eacr.sl = 1;
                 eacr.e0 = 0;
@@ -985,19 +999,22 @@ static void etr_work_fn(struct work_struct *work)
                         eacr.es = 0;
                 sync_port = (etr_port1_uptodate &&
                              etr_port_valid(&etr_port1, 1)) ? 1 : -1;
-                clear_bit(ETR_FLAG_EACCES, &etr_flags);
         } else {
                 /* Both ports not usable. */
                 eacr.es = eacr.sl = 0;
                 sync_port = -1;
-                set_bit(ETR_FLAG_EACCES, &etr_flags);
+                clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);
         }
 
+        if (!test_bit(CLOCK_SYNC_ETR, &clock_sync_flags))
+                eacr.es = 0;
+
         /*
          * If the clock is in sync just update the eacr and return.
          * If there is no valid sync port wait for a port update.
          */
-        if (eacr.es || sync_port < 0) {
+        if (test_bit(CLOCK_SYNC_STP, &clock_sync_flags) ||
+            eacr.es || sync_port < 0) {
                 etr_update_eacr(eacr);
                 etr_set_tolec_timeout(now);
                 return;
@@ -1018,11 +1035,13 @@ static void etr_work_fn(struct work_struct *work)
          * and set up a timer to try again after 0.5 seconds
          */
         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) {
                 /* Sync failed. Try again in 1/2 second. */
                 eacr.es = 0;
                 etr_update_eacr(eacr);
+                clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);
                 etr_set_sync_timeout();
         } else
                 etr_set_tolec_timeout(now);
@@ -1097,8 +1116,8 @@ static ssize_t etr_online_store(struct sys_device *dev,
         value = simple_strtoul(buf, NULL, 0);
         if (value != 0 && value != 1)
                 return -EINVAL;
-        if (test_bit(ETR_FLAG_ENOSYS, &etr_flags))
-                return -ENOSYS;
+        if (!test_bit(CLOCK_SYNC_HAS_ETR, &clock_sync_flags))
+                return -EOPNOTSUPP;
         if (dev == &etr_port0_dev) {
                 if (etr_port0_online == value)
                         return count;   /* Nothing to do. */
@@ -1292,3 +1311,318 @@ out:
 }
 
 device_initcall(etr_init_sysfs);
+
+/*
+ * Server Time Protocol (STP) code.
+ */
+static int stp_online;
+static struct stp_sstpi stp_info;
+static void *stp_page;
+
+static void stp_work_fn(struct work_struct *work);
+static DECLARE_WORK(stp_work, stp_work_fn);
+
+static int __init early_parse_stp(char *p)
+{
+        if (strncmp(p, "off", 3) == 0)
+                stp_online = 0;
+        else if (strncmp(p, "on", 2) == 0)
+                stp_online = 1;
+        return 0;
+}
+early_param("stp", early_parse_stp);
+
+/*
+ * Reset STP attachment.
+ */
+static void stp_reset(void)
+{
+        int rc;
+
+        stp_page = alloc_bootmem_pages(PAGE_SIZE);
+        rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000);
+        if (rc == 1)
+                set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags);
+        else if (stp_online) {
+                printk(KERN_WARNING "Running on non STP capable machine.\n");
+                free_bootmem((unsigned long) stp_page, PAGE_SIZE);
+                stp_page = NULL;
+                stp_online = 0;
+        }
+}
+
+static int __init stp_init(void)
+{
+        if (test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags) && stp_online)
+                schedule_work(&stp_work);
+        return 0;
+}
+
+arch_initcall(stp_init);
+
+/*
+ * STP timing alert. There are three causes:
+ * 1) timing status change
+ * 2) link availability change
+ * 3) time control parameter change
+ * In all three cases we are only interested in the clock source state.
+ * If a STP clock source is now available use it.
+ */
+static void stp_timing_alert(struct stp_irq_parm *intparm)
+{
+        if (intparm->tsc || intparm->lac || intparm->tcpc)
+                schedule_work(&stp_work);
+}
+
+/*
+ * STP sync check machine check. This is called when the timing state
+ * changes from the synchronized state to the unsynchronized state.
+ * After a STP sync check the clock is not in sync. The machine check
+ * is broadcasted to all cpus at the same time.
+ */
+void stp_sync_check(void)
+{
+        if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
+                return;
+        disable_sync_clock(NULL);
+        schedule_work(&stp_work);
+}
+
+/*
+ * STP island condition machine check. This is called when an attached
+ * server  attempts to communicate over an STP link and the servers
+ * have matching CTN ids and have a valid stratum-1 configuration
+ * but the configurations do not match.
+ */
+void stp_island_check(void)
+{
+        if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
+                return;
+        disable_sync_clock(NULL);
+        schedule_work(&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)
+{
+        struct clock_sync_data stp_sync;
+        unsigned long long old_clock, delta;
+        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;
+
+        /*
+         * 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, 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);
+
+        rc = 0;
+        if (stp_info.todoff[0] || stp_info.todoff[1] ||
+            stp_info.todoff[2] || stp_info.todoff[3] ||
+            stp_info.tmd != 2) {
+                old_clock = get_clock();
+                rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0);
+                if (rc == 0) {
+                        delta = adjust_time(old_clock, get_clock(), 0);
+                        fixup_clock_comparator(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;
+                clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
+                if (etr_port0_online || etr_port1_online)
+                        schedule_work(&etr_work);
+        } else
+                stp_sync.in_sync = 1;
+
+        local_irq_enable();
+        smp_call_function(clock_sync_cpu_end, NULL, 0, 0);
+        preempt_enable();
+}
+
+/*
+ * STP class sysfs interface functions
+ */
+static struct sysdev_class stp_sysclass = {
+        .name   = "stp",
+};
+
+static ssize_t stp_ctn_id_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online)
+                return -ENODATA;
+        return sprintf(buf, "%016llx\n",
+                       *(unsigned long long *) stp_info.ctnid);
+}
+
+static SYSDEV_CLASS_ATTR(ctn_id, 0400, stp_ctn_id_show, NULL);
+
+static ssize_t stp_ctn_type_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online)
+                return -ENODATA;
+        return sprintf(buf, "%i\n", stp_info.ctn);
+}
+
+static SYSDEV_CLASS_ATTR(ctn_type, 0400, stp_ctn_type_show, NULL);
+
+static ssize_t stp_dst_offset_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online || !(stp_info.vbits & 0x2000))
+                return -ENODATA;
+        return sprintf(buf, "%i\n", (int)(s16) stp_info.dsto);
+}
+
+static SYSDEV_CLASS_ATTR(dst_offset, 0400, stp_dst_offset_show, NULL);
+
+static ssize_t stp_leap_seconds_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online || !(stp_info.vbits & 0x8000))
+                return -ENODATA;
+        return sprintf(buf, "%i\n", (int)(s16) stp_info.leaps);
+}
+
+static SYSDEV_CLASS_ATTR(leap_seconds, 0400, stp_leap_seconds_show, NULL);
+
+static ssize_t stp_stratum_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online)
+                return -ENODATA;
+        return sprintf(buf, "%i\n", (int)(s16) stp_info.stratum);
+}
+
+static SYSDEV_CLASS_ATTR(stratum, 0400, stp_stratum_show, NULL);
+
+static ssize_t stp_time_offset_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online || !(stp_info.vbits & 0x0800))
+                return -ENODATA;
+        return sprintf(buf, "%i\n", (int) stp_info.tto);
+}
+
+static SYSDEV_CLASS_ATTR(time_offset, 0400, stp_time_offset_show, NULL);
+
+static ssize_t stp_time_zone_offset_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online || !(stp_info.vbits & 0x4000))
+                return -ENODATA;
+        return sprintf(buf, "%i\n", (int)(s16) stp_info.tzo);
+}
+
+static SYSDEV_CLASS_ATTR(time_zone_offset, 0400,
+                         stp_time_zone_offset_show, NULL);
+
+static ssize_t stp_timing_mode_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online)
+                return -ENODATA;
+        return sprintf(buf, "%i\n", stp_info.tmd);
+}
+
+static SYSDEV_CLASS_ATTR(timing_mode, 0400, stp_timing_mode_show, NULL);
+
+static ssize_t stp_timing_state_show(struct sysdev_class *class, char *buf)
+{
+        if (!stp_online)
+                return -ENODATA;
+        return sprintf(buf, "%i\n", stp_info.tst);
+}
+
+static SYSDEV_CLASS_ATTR(timing_state, 0400, stp_timing_state_show, NULL);
+
+static ssize_t stp_online_show(struct sysdev_class *class, char *buf)
+{
+        return sprintf(buf, "%i\n", stp_online);
+}
+
+static ssize_t stp_online_store(struct sysdev_class *class,
+                                const char *buf, size_t count)
+{
+        unsigned int value;
+
+        value = simple_strtoul(buf, NULL, 0);
+        if (value != 0 && value != 1)
+                return -EINVAL;
+        if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
+                return -EOPNOTSUPP;
+        stp_online = value;
+        schedule_work(&stp_work);
+        return count;
+}
+
+/*
+ * Can't use SYSDEV_CLASS_ATTR because the attribute should be named
+ * stp/online but attr_online already exists in this file ..
+ */
+static struct sysdev_class_attribute attr_stp_online = {
+        .attr = { .name = "online", .mode = 0600 },
+        .show   = stp_online_show,
+        .store  = stp_online_store,
+};
+
+static struct sysdev_class_attribute *stp_attributes[] = {
+        &attr_ctn_id,
+        &attr_ctn_type,
+        &attr_dst_offset,
+        &attr_leap_seconds,
+        &attr_stp_online,
+        &attr_stratum,
+        &attr_time_offset,
+        &attr_time_zone_offset,
+        &attr_timing_mode,
+        &attr_timing_state,
+        NULL
+};
+
+static int __init stp_init_sysfs(void)
+{
+        struct sysdev_class_attribute **attr;
+        int rc;
+
+        rc = sysdev_class_register(&stp_sysclass);
+        if (rc)
+                goto out;
+        for (attr = stp_attributes; *attr; attr++) {
+                rc = sysdev_class_create_file(&stp_sysclass, *attr);
+                if (rc)
+                        goto out_unreg;
+        }
+        return 0;
+out_unreg:
+        for (; attr >= stp_attributes; attr--)
+                sysdev_class_remove_file(&stp_sysclass, *attr);
+        sysdev_class_unregister(&stp_sysclass);
+out:
+        return rc;
+}
+
+device_initcall(stp_init_sysfs);
diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index cb36f7929786..62b0b16fe3d3 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -874,3 +874,52 @@ exit:
 
 EXPORT_SYMBOL_GPL(css_general_characteristics);
 EXPORT_SYMBOL_GPL(css_chsc_characteristics);
+
+int chsc_sstpc(void *page, unsigned int op, u16 ctrl)
+{
+        struct {
+                struct chsc_header request;
+                unsigned int rsvd0;
+                unsigned int op : 8;
+                unsigned int rsvd1 : 8;
+                unsigned int ctrl : 16;
+                unsigned int rsvd2[5];
+                struct chsc_header response;
+                unsigned int rsvd3[7];
+        } __attribute__ ((packed)) *rr;
+        int rc;
+
+        memset(page, 0, PAGE_SIZE);
+        rr = page;
+        rr->request.length = 0x0020;
+        rr->request.code = 0x0033;
+        rr->op = op;
+        rr->ctrl = ctrl;
+        rc = chsc(rr);
+        if (rc)
+                return -EIO;
+        rc = (rr->response.code == 0x0001) ? 0 : -EIO;
+        return rc;
+}
+
+int chsc_sstpi(void *page, void *result, size_t size)
+{
+        struct {
+                struct chsc_header request;
+                unsigned int rsvd0[3];
+                struct chsc_header response;
+                char data[size];
+        } __attribute__ ((packed)) *rr;
+        int rc;
+
+        memset(page, 0, PAGE_SIZE);
+        rr = page;
+        rr->request.length = 0x0010;
+        rr->request.code = 0x0038;
+        rc = chsc(rr);
+        if (rc)
+                return -EIO;
+        memcpy(result, &rr->data, size);
+        return (rr->response.code == 0x0001) ? 0 : -EIO;
+}
+
diff --git a/drivers/s390/s390mach.c b/drivers/s390/s390mach.c
index fe75152a5084..834e9ee7e934 100644
--- a/drivers/s390/s390mach.c
+++ b/drivers/s390/s390mach.c
@@ -458,6 +458,10 @@ s390_do_machine_check(struct pt_regs *regs)
                         etr_sync_check();
                 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
                         etr_switch_to_local();
+                if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
+                        stp_sync_check();
+                if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
+                        stp_island_check();
         }
 
         if (mci->se)
diff --git a/drivers/s390/s390mach.h b/drivers/s390/s390mach.h
index f11e574076d8..d39f8b697d27 100644
--- a/drivers/s390/s390mach.h
+++ b/drivers/s390/s390mach.h
@@ -112,6 +112,9 @@ static inline int stcrw(struct crw *pcrw )
 #define ED_ETR_SYNC     12      /* External damage ETR sync check */
 #define ED_ETR_SWITCH   13      /* External damage ETR switch to local */
 
+#define ED_STP_SYNC     7       /* External damage STP sync check */
+#define ED_STP_ISLAND   6       /* External damage STP island check */
+
 struct pt_regs;
 
 void s390_handle_mcck(void);
diff --git a/include/asm-s390/etr.h b/include/asm-s390/etr.h
index b498f19bb9a7..80ef58c61970 100644
--- a/include/asm-s390/etr.h
+++ b/include/asm-s390/etr.h
@@ -122,7 +122,7 @@ struct etr_aib {
 } __attribute__ ((packed,aligned(8)));
 
 /* ETR interruption parameter */
-struct etr_interruption_parameter {
+struct etr_irq_parm {
         unsigned int _pad0      : 8;
         unsigned int pc0        : 1;    /* port 0 state change */
         unsigned int pc1        : 1;    /* port 1 state change */
@@ -213,7 +213,46 @@ static inline int etr_ptff(void *ptff_block, unsigned int func)
 #define ETR_PTFF_SGS    0x43    /* set gross steering rate */
 
 /* Functions needed by the machine check handler */
-extern void etr_switch_to_local(void);
-extern void etr_sync_check(void);
+void etr_switch_to_local(void);
+void etr_sync_check(void);
+
+/* STP interruption parameter */
+struct stp_irq_parm {
+        unsigned int _pad0      : 14;
+        unsigned int tsc        : 1;    /* Timing status change */
+        unsigned int lac        : 1;    /* Link availability change */
+        unsigned int tcpc       : 1;    /* Time control parameter change */
+        unsigned int _pad2      : 15;
+} __attribute__ ((packed));
+
+#define STP_OP_SYNC     1
+#define STP_OP_CTRL     3
+
+struct stp_sstpi {
+        unsigned int rsvd0;
+        unsigned int rsvd1 : 8;
+        unsigned int stratum : 8;
+        unsigned int vbits : 16;
+        unsigned int leaps : 16;
+        unsigned int tmd : 4;
+        unsigned int ctn : 4;
+        unsigned int rsvd2 : 3;
+        unsigned int c : 1;
+        unsigned int tst : 4;
+        unsigned int tzo : 16;
+        unsigned int dsto : 16;
+        unsigned int ctrl : 16;
+        unsigned int rsvd3 : 16;
+        unsigned int tto;
+        unsigned int rsvd4;
+        unsigned int ctnid[3];
+        unsigned int rsvd5;
+        unsigned int todoff[4];
+        unsigned int rsvd6[48];
+} __attribute__ ((packed));
+
+/* Functions needed by the machine check handler */
+void stp_sync_check(void);
+void stp_island_check(void);
 
 #endif /* __S390_ETR_H */