Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d54853ef8cb17296ac7bce9c77430fb7c80532d0
Commit:     d54853ef8cb17296ac7bce9c77430fb7c80532d0
Parent:     c1821c2e9711adc3cd298a16b7237c92a2cee78d
Author:     Martin Schwidefsky <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 5 21:18:19 2007 +0100
Committer:  Martin Schwidefsky <[EMAIL PROTECTED]>
CommitDate: Mon Feb 5 21:18:19 2007 +0100

    [S390] ETR support.
    
    This patch adds support for clock synchronization to an external time
    reference (ETR). The external time reference sends an oscillator
    signal and a synchronization signal every 2^20 microseconds to keep
    the TOD clocks of all connected servers in sync. For availability
    two ETR units can be connected to a machine. If the clock deviates
    for more than the sync-check tolerance all cpus get a machine check
    that indicates that the clock is out of sync. For the lovely details
    how to get the clock back in sync see the code below.
    
    Signed-off-by: Martin Schwidefsky <[EMAIL PROTECTED]>
---
 arch/s390/kernel/s390_ext.c    |    8 +-
 arch/s390/kernel/smp.c         |    3 +-
 arch/s390/kernel/time.c        | 1179 +++++++++++++++++++++++++++++++++++++---
 arch/s390/kernel/vtime.c       |    8 +-
 arch/s390/lib/delay.c          |   48 ++-
 drivers/s390/block/dasd.c      |   13 +
 drivers/s390/block/dasd_eckd.c |   44 +-
 drivers/s390/cio/cio.c         |   17 +-
 drivers/s390/s390mach.c        |   17 +-
 drivers/s390/s390mach.h        |    3 +
 include/asm-s390/etr.h         |  219 ++++++++
 include/asm-s390/hardirq.h     |    2 +-
 include/asm-s390/timex.h       |   36 ++
 13 files changed, 1488 insertions(+), 109 deletions(-)

diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index bc5beaa..acf93db 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -125,14 +125,12 @@ void do_extint(struct pt_regs *regs, unsigned short code)
                 * Make sure that the i/o interrupt did not "overtake"
                 * the last HZ timer interrupt.
                 */
-               account_ticks();
+               account_ticks(S390_lowcore.int_clock);
        kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
         index = ext_hash(code);
        for (p = ext_int_hash[index]; p; p = p->next) {
-               if (likely(p->code == code)) {
-                       if (likely(p->handler))
-                               p->handler(code);
-               }
+               if (likely(p->code == code))
+                       p->handler(code);
        }
        irq_exit();
        set_irq_regs(old_regs);
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index cb155d9..08f9a4d 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -457,9 +457,10 @@ int __devinit start_secondary(void *cpuvoid)
         /* Setup the cpu */
         cpu_init();
        preempt_disable();
-        /* init per CPU timer */
+       /* Enable TOD clock interrupts on the secondary cpu. */
         init_cpu_timer();
 #ifdef CONFIG_VIRT_TIMER
+       /* Enable cpu timer interrupts on the secondary cpu. */
         init_cpu_vtimer();
 #endif
        /* Enable pfault pseudo page faults on this cpu. */
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 5d4a190..39a72d3 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -37,11 +37,15 @@
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
 #include <asm/timer.h>
+#include <asm/etr.h>
 
 /* change this if you have some constant time drift */
 #define USECS_PER_JIFFY     ((unsigned long) 1000000/HZ)
 #define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
 
+/* The value of the TOD clock for 1.1.1970. */
+#define TOD_UNIX_EPOCH 0x7d91048bca000000ULL
+
 /*
  * Create a small time difference between the timer interrupts
  * on the different cpus to avoid lock contention.
@@ -51,6 +55,7 @@
 #define TICK_SIZE tick
 
 static ext_int_info_t ext_int_info_cc;
+static ext_int_info_t ext_int_etr_cc;
 static u64 init_timer_cc;
 static u64 jiffies_timer_cc;
 static u64 xtime_cc;
@@ -89,29 +94,21 @@ void tod_to_timeval(__u64 todval, struct timespec *xtime)
 #define s390_do_profile()      do { ; } while(0)
 #endif /* CONFIG_PROFILING */
 
-
 /*
- * timer_interrupt() needs to keep up the real-time clock,
- * as well as call the "do_timer()" routine every clocktick
+ * Advance the per cpu tick counter up to the time given with the
+ * "time" argument. The per cpu update consists of accounting
+ * the virtual cpu time, calling update_process_times and calling
+ * the profiling hook. If xtime is before time it is advanced as well.
  */
-void account_ticks(void)
+void account_ticks(u64 time)
 {
-       __u64 tmp;
        __u32 ticks;
+       __u64 tmp;
 
        /* Calculate how many ticks have passed. */
-       if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) {
-               /*
-                * We have to program the clock comparator even if
-                * no tick has passed. That happens if e.g. an i/o
-                * interrupt wakes up an idle processor that has
-                * switched off its hz timer.
-                */
-               tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
-               asm volatile ("SCKC %0" : : "m" (tmp));
+       if (time < S390_lowcore.jiffy_timer)
                return;
-       }
-       tmp = S390_lowcore.int_clock - S390_lowcore.jiffy_timer;
+       tmp = time - S390_lowcore.jiffy_timer;
        if (tmp >= 2*CLK_TICKS_PER_JIFFY) {  /* more than two ticks ? */
                ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1;
                S390_lowcore.jiffy_timer +=
@@ -124,10 +121,6 @@ void account_ticks(void)
                S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
        }
 
-       /* set clock comparator for next tick */
-       tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
-        asm volatile ("SCKC %0" : : "m" (tmp));
-
 #ifdef CONFIG_SMP
        /*
         * Do not rely on the boot cpu to do the calls to do_timer.
@@ -210,7 +203,7 @@ static inline void stop_hz_timer(void)
                if (timer >= jiffies_timer_cc)
                        todval = timer;
        }
-       asm volatile ("SCKC %0" : : "m" (todval));
+       set_clock_comparator(todval);
 }
 
 /*
@@ -223,7 +216,8 @@ static inline void start_hz_timer(void)
 
        if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
                return;
-       account_ticks();
+       account_ticks(get_clock());
+       set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
        cpu_clear(smp_processor_id(), nohz_cpu_mask);
 }
 
@@ -254,21 +248,56 @@ static void __init nohz_init(void)
 #endif
 
 /*
- * Start the clock comparator on the current CPU.
+ * Set up per cpu jiffy timer and set the clock comparator.
+ */
+static void setup_jiffy_timer(void)
+{
+       /* Set up clock comparator to next jiffy. */
+       S390_lowcore.jiffy_timer =
+               jiffies_timer_cc + (jiffies_64 + 1) * CLK_TICKS_PER_JIFFY;
+       set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
+}
+
+/*
+ * Set up lowcore and control register of the current cpu to
+ * enable TOD clock and clock comparator interrupts.
  */
 void init_cpu_timer(void)
 {
-       unsigned long cr0;
-       __u64 timer;
+       setup_jiffy_timer();
+
+       /* Enable clock comparator timer interrupt. */
+       __ctl_set_bit(0,11);
+
+       /* Always allow ETR external interrupts, even without an ETR. */
+       __ctl_set_bit(0, 4);
+}
+
+static void clock_comparator_interrupt(__u16 code)
+{
+       /* set clock comparator for next tick */
+       set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
+}
+
+static void etr_reset(void);
+static void etr_init(void);
+static void etr_ext_handler(__u16);
+
+/*
+ * Get the TOD clock running.
+ */
+static u64 __init reset_tod_clock(void)
+{
+       u64 time;
+
+       etr_reset();
+       if (store_clock(&time) == 0)
+               return time;
+       /* TOD clock not running. Set the clock to Unix Epoch. */
+       if (set_clock(TOD_UNIX_EPOCH) != 0 || store_clock(&time) != 0)
+               panic("TOD clock not operational.");
 
-       timer = jiffies_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY;
-       S390_lowcore.jiffy_timer = timer + CLK_TICKS_PER_JIFFY;
-       timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
-       asm volatile ("SCKC %0" : : "m" (timer));
-        /* allow clock comparator timer interrupt */
-       __ctl_store(cr0, 0, 0);
-        cr0 |= 0x800;
-       __ctl_load(cr0, 0, 0);
+       return TOD_UNIX_EPOCH;
 }
 
 static cycle_t read_tod_clock(void)
@@ -293,48 +322,31 @@ static struct clocksource clocksource_tod = {
  */
 void __init time_init(void)
 {
-       __u64 set_time_cc;
-       int cc;
-
-        /* kick the TOD clock */
-       asm volatile(
-               "       stck    0(%2)\n"
-               "       ipm     %0\n"
-               "       srl     %0,28"
-               : "=d" (cc), "=m" (init_timer_cc)
-               : "a" (&init_timer_cc) : "cc");
-        switch (cc) {
-        case 0: /* clock in set state: all is fine */
-                break;
-        case 1: /* clock in non-set state: FIXME */
-                printk("time_init: TOD clock in non-set state\n");
-                break;
-        case 2: /* clock in error state: FIXME */
-                printk("time_init: TOD clock in error state\n");
-                break;
-        case 3: /* clock in stopped or not-operational state: FIXME */
-                printk("time_init: TOD clock stopped/non-operational\n");
-                break;
-        }
+       init_timer_cc = reset_tod_clock();
+       xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY;
        jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY;
 
        /* set xtime */
-       xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY;
-       set_time_cc = init_timer_cc - 0x8126d60e46000000LL +
-               (0x3c26700LL*1000000*4096);
-        tod_to_timeval(set_time_cc, &xtime);
+       tod_to_timeval(init_timer_cc - TOD_UNIX_EPOCH, &xtime);
         set_normalized_timespec(&wall_to_monotonic,
                                 -xtime.tv_sec, -xtime.tv_nsec);
 
        /* request the clock comparator external interrupt */
-       if (register_early_external_interrupt(0x1004, NULL,
+       if (register_early_external_interrupt(0x1004,
+                                             clock_comparator_interrupt,
                                              &ext_int_info_cc) != 0)
                 panic("Couldn't request external interrupt 0x1004");
 
        if (clocksource_register(&clocksource_tod) != 0)
                panic("Could not register TOD clock source");
 
-        init_cpu_timer();
+       /* request the etr external interrupt */
+       if (register_early_external_interrupt(0x1406, etr_ext_handler,
+                                             &ext_int_etr_cc) != 0)
+               panic("Couldn't request external interrupt 0x1406");
+
+       /* Enable TOD clock interrupts on the boot cpu. */
+       init_cpu_timer();
 
 #ifdef CONFIG_NO_IDLE_HZ
        nohz_init();
@@ -343,5 +355,1048 @@ void __init time_init(void)
 #ifdef CONFIG_VIRT_TIMER
        vtime_init();
 #endif
+       etr_init();
+}
+
+/*
+ * External Time Reference (ETR) code.
+ */
+static int etr_port0_online;
+static int etr_port1_online;
+
+static int __init early_parse_etr(char *p)
+{
+       if (strncmp(p, "off", 3) == 0)
+               etr_port0_online = etr_port1_online = 0;
+       else if (strncmp(p, "port0", 5) == 0)
+               etr_port0_online = 1;
+       else if (strncmp(p, "port1", 5) == 0)
+               etr_port1_online = 1;
+       else if (strncmp(p, "on", 2) == 0)
+               etr_port0_online = etr_port1_online = 1;
+       return 0;
+}
+early_param("etr", early_parse_etr);
+
+enum etr_event {
+       ETR_EVENT_PORT0_CHANGE,
+       ETR_EVENT_PORT1_CHANGE,
+       ETR_EVENT_PORT_ALERT,
+       ETR_EVENT_SYNC_CHECK,
+       ETR_EVENT_SWITCH_LOCAL,
+       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
+ *  0  0  x  0 0  0  0  0  initial, disabled state
+ *  0  0  x  0 1  1  0  0  port 1 online
+ *  0  0  x  1 0  1  0  0  port 0 online
+ *  0  0  x  1 1  1  0  0  both ports online
+ *  0  1  x  0 1  1  0  0  port 1 online and usable, ETR or PPS mode
+ *  0  1  x  0 1  1  0  1  port 1 online, usable and ETR mode
+ *  0  1  x  0 1  1  1  0  port 1 online, usable, PPS mode, in-sync
+ *  0  1  x  0 1  1  1  1  port 1 online, usable, ETR mode, in-sync
+ *  0  1  x  1 1  1  0  0  both ports online, port 1 usable
+ *  0  1  x  1 1  1  1  0  both ports online, port 1 usable, PPS mode, in-sync
+ *  0  1  x  1 1  1  1  1  both ports online, port 1 usable, ETR mode, in-sync
+ *  1  0  x  1 0  1  0  0  port 0 online and usable, ETR or PPS mode
+ *  1  0  x  1 0  1  0  1  port 0 online, usable and ETR mode
+ *  1  0  x  1 0  1  1  0  port 0 online, usable, PPS mode, in-sync
+ *  1  0  x  1 0  1  1  1  port 0 online, usable, ETR mode, in-sync
+ *  1  0  x  1 1  1  0  0  both ports online, port 0 usable
+ *  1  0  x  1 1  1  1  0  both ports online, port 0 usable, PPS mode, in-sync
+ *  1  0  x  1 1  1  1  1  both ports online, port 0 usable, ETR mode, in-sync
+ *  1  1  x  1 1  1  1  0  both ports online & usable, ETR, in-sync
+ *  1  1  x  1 1  1  1  1  both ports online & usable, ETR, in-sync
+ */
+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 struct tasklet_struct etr_tasklet;
+static DEFINE_PER_CPU(atomic_t, etr_sync_word);
+
+static void etr_timeout(unsigned long dummy);
+static void etr_tasklet_fn(unsigned long dummy);
+
+/*
+ * 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)
+{
+       etr_eacr =  (struct etr_eacr) {
+               .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)
+               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;
+               }
+       }
+}
+
+static void etr_init(void)
+{
+       struct etr_aib aib;
+
+       if (test_bit(ETR_FLAG_ENOSYS, &etr_flags))
+               return;
+       /* Check if this machine has the steai instruction. */
+       if (etr_steai(&aib, ETR_STEAI_STEPPING_PORT) == 0)
+               set_bit(ETR_FLAG_STEAI, &etr_flags);
+       setup_timer(&etr_timer, etr_timeout, 0UL);
+       tasklet_init(&etr_tasklet, etr_tasklet_fn, 0);
+       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);
+               tasklet_hi_schedule(&etr_tasklet);
+       }
+       if (etr_port1_online) {
+               set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events);
+               tasklet_hi_schedule(&etr_tasklet);
+       }
+}
+
+/*
+ * Two sorts of ETR machine checks. The architecture reads:
+ * "When a machine-check niterruption occurs and if a switch-to-local or
+ *  ETR-sync-check interrupt request is pending but disabled, this pending
+ *  disabled interruption request is indicated and is cleared".
+ * Which means that we can get etr_switch_to_local events from the machine
+ * check handler although the interruption condition is disabled. Lovely..
+ */
+
+/*
+ * Switch to local machine check. This is called when the last usable
+ * ETR port goes inactive. After switch to local the clock is not in sync.
+ */
+void etr_switch_to_local(void)
+{
+       if (!etr_eacr.sl)
+               return;
+       etr_disable_sync_clock(NULL);
+       set_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events);
+       tasklet_hi_schedule(&etr_tasklet);
+}
+
+/*
+ * ETR sync check machine check. This is called when the ETR OTE and the
+ * local clock OTE are farther apart than the ETR sync check tolerance.
+ * After a ETR sync check the clock is not in sync. The machine check
+ * is broadcasted to all cpus at the same time.
+ */
+void etr_sync_check(void)
+{
+       if (!etr_eacr.es)
+               return;
+       etr_disable_sync_clock(NULL);
+       set_bit(ETR_EVENT_SYNC_CHECK, &etr_events);
+       tasklet_hi_schedule(&etr_tasklet);
+}
+
+/*
+ * ETR external interrupt. 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)
+{
+       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);
+       if (intparm->pc1)
+               /* ETR port 1 state change. */
+               set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events);
+       if (intparm->eai)
+               /*
+                * ETR port alert on either port 0, 1 or both.
+                * Both ports are not up-to-date now.
+                */
+               set_bit(ETR_EVENT_PORT_ALERT, &etr_events);
+       tasklet_hi_schedule(&etr_tasklet);
+}
+
+static void etr_timeout(unsigned long dummy)
+{
+       set_bit(ETR_EVENT_UPDATE, &etr_events);
+       tasklet_hi_schedule(&etr_tasklet);
+}
+
+/*
+ * Check if the etr mode is pss.
+ */
+static inline int etr_mode_is_pps(struct etr_eacr eacr)
+{
+       return eacr.es && !eacr.sl;
+}
+
+/*
+ * Check if the etr mode is etr.
+ */
+static inline int etr_mode_is_etr(struct etr_eacr eacr)
+{
+       return eacr.es && eacr.sl;
+}
+
+/*
+ * Check if the port can be used for TOD synchronization.
+ * For PPS mode the port has to receive OTEs. For ETR mode
+ * the port has to receive OTEs, the ETR stepping bit has to
+ * be zero and the validity bits for data frame 1, 2, and 3
+ * have to be 1.
+ */
+static int etr_port_valid(struct etr_aib *aib, int port)
+{
+       unsigned int psc;
+
+       /* Check that this port is receiving OTEs. */
+       if (aib->tsp == 0)
+               return 0;
+
+       psc = port ? aib->esw.psc1 : aib->esw.psc0;
+       if (psc == etr_lpsc_pps_mode)
+               return 1;
+       if (psc == etr_lpsc_operational_step)
+               return !aib->esw.y && aib->slsw.v1 &&
+                       aib->slsw.v2 && aib->slsw.v3;
+       return 0;
+}
+
+/*
+ * Check if two ports are on the same network.
+ */
+static int etr_compare_network(struct etr_aib *aib1, struct etr_aib *aib2)
+{
+       // FIXME: any other fields we have to compare?
+       return aib1->edf1.net_id == aib2->edf1.net_id;
+}
+
+/*
+ * Wrapper for etr_stei that converts physical port states
+ * to logical port states to be consistent with the output
+ * of stetr (see etr_psc vs. etr_lpsc).
+ */
+static void etr_steai_cv(struct etr_aib *aib, unsigned int func)
+{
+       BUG_ON(etr_steai(aib, func) != 0);
+       /* Convert port state to logical port state. */
+       if (aib->esw.psc0 == 1)
+               aib->esw.psc0 = 2;
+       else if (aib->esw.psc0 == 0 && aib->esw.p == 0)
+               aib->esw.psc0 = 1;
+       if (aib->esw.psc1 == 1)
+               aib->esw.psc1 = 2;
+       else if (aib->esw.psc1 == 0 && aib->esw.p == 1)
+               aib->esw.psc1 = 1;
+}
+
+/*
+ * Check if the aib a2 is still connected to the same attachment as
+ * aib a1, the etv values differ by one and a2 is valid.
+ */
+static int etr_aib_follows(struct etr_aib *a1, struct etr_aib *a2, int p)
+{
+       int state_a1, state_a2;
+
+       /* Paranoia check: e0/e1 should better be the same. */
+       if (a1->esw.eacr.e0 != a2->esw.eacr.e0 ||
+           a1->esw.eacr.e1 != a2->esw.eacr.e1)
+               return 0;
+
+       /* Still connected to the same etr ? */
+       state_a1 = p ? a1->esw.psc1 : a1->esw.psc0;
+       state_a2 = p ? a2->esw.psc1 : a2->esw.psc0;
+       if (state_a1 == etr_lpsc_operational_step) {
+               if (state_a2 != etr_lpsc_operational_step ||
+                   a1->edf1.net_id != a2->edf1.net_id ||
+                   a1->edf1.etr_id != a2->edf1.etr_id ||
+                   a1->edf1.etr_pn != a2->edf1.etr_pn)
+                       return 0;
+       } else if (state_a2 != etr_lpsc_pps_mode)
+               return 0;
+
+       /* The ETV value of a2 needs to be ETV of a1 + 1. */
+       if (a1->edf2.etv + 1 != a2->edf2.etv)
+               return 0;
+
+       if (!etr_port_valid(a2, p))
+               return 0;
+
+       return 1;
+}
+
+/*
+ * The time is "clock". xtime 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 void etr_adjust_time(unsigned long long clock, unsigned long long delay)
+{
+       unsigned long long delta, ticks;
+       struct timex adjust;
+
+       /*
+        * We don't have to take the xtime lock because the cpu
+        * executing etr_adjust_time is running disabled in
+        * tasklet context and all other cpus are looping in
+        * etr_sync_cpu_start.
+        */
+       if (clock > xtime_cc) {
+               /* It is later than we thought. */
+               delta = ticks = clock - xtime_cc;
+               delta = ticks = (delta < delay) ? 0 : delta - delay;
+               delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
+               init_timer_cc = init_timer_cc + delta;
+               jiffies_timer_cc = jiffies_timer_cc + delta;
+               xtime_cc = xtime_cc + delta;
+               adjust.offset = ticks * (1000000 / HZ);
+       } else {
+               /* It is earlier than we thought. */
+               delta = ticks = xtime_cc - clock;
+               delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
+               init_timer_cc = init_timer_cc - delta;
+               jiffies_timer_cc = jiffies_timer_cc - delta;
+               xtime_cc = xtime_cc - delta;
+               adjust.offset = -ticks * (1000000 / HZ);
+       }
+       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);
+       }
+}
+
+static void etr_sync_cpu_start(void *dummy)
+{
+       int *in_sync = dummy;
+
+       etr_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 (*in_sync == 0)
+               __udelay(1);
+       if (*in_sync != 1)
+               /* Didn't work. Clear per-cpu in sync bit again. */
+               etr_disable_sync_clock(NULL);
+       /*
+        * This round of TOD syncing is done. Set the clock comparator
+        * to the next tick and let the processor continue.
+        */
+       setup_jiffy_timer();
+}
+
+static void etr_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)
+{
+       struct etr_aib *sync_port;
+       unsigned long long clock, delay;
+       int in_sync, 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;
+
+       /*
+        * 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.
+        */
+       in_sync = 0;
+       preempt_disable();
+       smp_call_function(etr_sync_cpu_start,&in_sync,0,0);
+       local_irq_disable();
+       etr_enable_sync_clock();
+
+       /* Set clock to next OTE. */
+       __ctl_set_bit(14, 21);
+       __ctl_set_bit(0, 29);
+       clock = ((unsigned long long) (aib->edf2.etv + 1)) << 32;
+       if (set_clock(clock) == 0) {
+               __udelay(1);    /* Wait for the clock to start. */
+               __ctl_clear_bit(0, 29);
+               __ctl_clear_bit(14, 21);
+               etr_stetr(aib);
+               /* Adjust Linux timing variables. */
+               delay = (unsigned long long)
+                       (aib->edf2.etv - sync_port->edf2.etv) << 32;
+               etr_adjust_time(clock, delay);
+               setup_jiffy_timer();
+               /* Verify that the clock is properly set. */
+               if (!etr_aib_follows(sync_port, aib, port)) {
+                       /* Didn't work. */
+                       etr_disable_sync_clock(NULL);
+                       in_sync = -EAGAIN;
+                       rc = -EAGAIN;
+               } else {
+                       in_sync = 1;
+                       rc = 0;
+               }
+       } else {
+               /* Could not set the clock ?!? */
+               __ctl_clear_bit(0, 29);
+               __ctl_clear_bit(14, 21);
+               etr_disable_sync_clock(NULL);
+               in_sync = -EAGAIN;
+               rc = -EAGAIN;
+       }
+       local_irq_enable();
+       smp_call_function(etr_sync_cpu_end,NULL,0,0);
+       preempt_enable();
+       return rc;
+}
+
+/*
+ * Handle the immediate effects of the different events.
+ * The port change event is used for online/offline changes.
+ */
+static struct etr_eacr etr_handle_events(struct etr_eacr eacr)
+{
+       if (test_and_clear_bit(ETR_EVENT_SYNC_CHECK, &etr_events))
+               eacr.es = 0;
+       if (test_and_clear_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events))
+               eacr.es = eacr.sl = 0;
+       if (test_and_clear_bit(ETR_EVENT_PORT_ALERT, &etr_events))
+               etr_port0_uptodate = etr_port1_uptodate = 0;
+
+       if (test_and_clear_bit(ETR_EVENT_PORT0_CHANGE, &etr_events)) {
+               if (eacr.e0)
+                       /*
+                        * Port change of an enabled port. We have to
+                        * assume that this can have caused an stepping
+                        * port switch.
+                        */
+                       etr_tolec = get_clock();
+               eacr.p0 = etr_port0_online;
+               if (!eacr.p0)
+                       eacr.e0 = 0;
+               etr_port0_uptodate = 0;
+       }
+       if (test_and_clear_bit(ETR_EVENT_PORT1_CHANGE, &etr_events)) {
+               if (eacr.e1)
+                       /*
+                        * Port change of an enabled port. We have to
+                        * assume that this can have caused an stepping
+                        * port switch.
+                        */
+                       etr_tolec = get_clock();
+               eacr.p1 = etr_port1_online;
+               if (!eacr.p1)
+                       eacr.e1 = 0;
+               etr_port1_uptodate = 0;
+       }
+       clear_bit(ETR_EVENT_UPDATE, &etr_events);
+       return eacr;
+}
+
+/*
+ * Set up a timer that expires after the etr_tolec + 1.6 seconds if
+ * one of the ports needs an update.
+ */
+static void etr_set_tolec_timeout(unsigned long long now)
+{
+       unsigned long micros;
+
+       if ((!etr_eacr.p0 || etr_port0_uptodate) &&
+           (!etr_eacr.p1 || etr_port1_uptodate))
+               return;
+       micros = (now > etr_tolec) ? ((now - etr_tolec) >> 12) : 0;
+       micros = (micros > 1600000) ? 0 : 1600000 - micros;
+       mod_timer(&etr_timer, jiffies + (micros * HZ) / 1000000 + 1);
+}
+
+/*
+ * Set up a time that expires after 1/2 second.
+ */
+static void etr_set_sync_timeout(void)
+{
+       mod_timer(&etr_timer, jiffies + HZ/2);
+}
+
+/*
+ * Update the aib information for one or both ports.
+ */
+static struct etr_eacr etr_handle_update(struct etr_aib *aib,
+                                        struct etr_eacr eacr)
+{
+       /* With both ports disabled the aib information is useless. */
+       if (!eacr.e0 && !eacr.e1)
+               return eacr;
+
+       /* Update port0 or port1 with aib stored in etr_tasklet_fn. */
+       if (aib->esw.q == 0) {
+               /* Information for port 0 stored. */
+               if (eacr.p0 && !etr_port0_uptodate) {
+                       etr_port0 = *aib;
+                       if (etr_port0_online)
+                               etr_port0_uptodate = 1;
+               }
+       } else {
+               /* Information for port 1 stored. */
+               if (eacr.p1 && !etr_port1_uptodate) {
+                       etr_port1 = *aib;
+                       if (etr_port0_online)
+                               etr_port1_uptodate = 1;
+               }
+       }
+
+       /*
+        * Do not try to get the alternate port aib if the clock
+        * is not in sync yet.
+        */
+       if (!eacr.es)
+               return eacr;
+
+       /*
+        * If steai is available we can get the information about
+        * 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 (eacr.p0 && !etr_port0_uptodate) {
+                       etr_steai_cv(&etr_port0, ETR_STEAI_PORT_0);
+                       etr_port0_uptodate = 1;
+               }
+               if (eacr.p1 && !etr_port1_uptodate) {
+                       etr_steai_cv(&etr_port1, ETR_STEAI_PORT_1);
+                       etr_port1_uptodate = 1;
+               }
+       } else {
+               /*
+                * One port was updated above, if the other
+                * port is not uptodate toggle dp bit.
+                */
+               if ((eacr.p0 && !etr_port0_uptodate) ||
+                   (eacr.p1 && !etr_port1_uptodate))
+                       eacr.dp ^= 1;
+               else
+                       eacr.dp = 0;
+       }
+       return eacr;
+}
+
+/*
+ * Write new etr control register if it differs from the current one.
+ * Return 1 if etr_tolec has been updated as well.
+ */
+static void etr_update_eacr(struct etr_eacr eacr)
+{
+       int dp_changed;
+
+       if (memcmp(&etr_eacr, &eacr, sizeof(eacr)) == 0)
+               /* No change, return. */
+               return;
+       /*
+        * The disable of an active port of the change of the data port
+        * bit can/will cause a change in the data port.
+        */
+       dp_changed = etr_eacr.e0 > eacr.e0 || etr_eacr.e1 > eacr.e1 ||
+               (etr_eacr.dp ^ eacr.dp) != 0;
+       etr_eacr = eacr;
+       etr_setr(&etr_eacr);
+       if (dp_changed)
+               etr_tolec = get_clock();
+}
+
+/*
+ * ETR tasklet. 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.
+ */
+static void etr_tasklet_fn(unsigned long dummy)
+{
+       unsigned long long now;
+       struct etr_eacr eacr;
+       struct etr_aib aib;
+       int sync_port;
+
+       /* Create working copy of etr_eacr. */
+       eacr = etr_eacr;
+
+       /* Check for the different events and their immediate effects. */
+       eacr = etr_handle_events(eacr);
+
+       /* Check if ETR is supposed to be active. */
+       eacr.ea = eacr.p0 || eacr.p1;
+       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);
+               del_timer_sync(&etr_timer);
+               etr_update_eacr(eacr);
+               set_bit(ETR_FLAG_EACCES, &etr_flags);
+               return;
+       }
+
+       /* Store aib to get the current ETR status word. */
+       BUG_ON(etr_stetr(&aib) != 0);
+       etr_port0.esw = etr_port1.esw = aib.esw;        /* Copy status word. */
+       now = get_clock();
+
+       /*
+        * Update the port information if the last stepping port change
+        * or data port change is older than 1.6 seconds.
+        */
+       if (now >= etr_tolec + (1600000 << 12))
+               eacr = etr_handle_update(&aib, eacr);
+
+       /*
+        * Select ports to enable. The prefered synchronization mode is PPS.
+        * If a port can be enabled depends on a number of things:
+        * 1) The port needs to be online and uptodate. A port is not
+        *    disabled just because it is not uptodate, but it is only
+        *    enabled if it is uptodate.
+        * 2) The port needs to have the same mode (pps / etr).
+        * 3) The port needs to be usable -> etr_port_valid() == 1
+        * 4) To enable the second port the clock needs to be in sync.
+        * 5) If both ports are useable and are ETR ports, the network id
+        *    has to be the same.
+        * The eacr.sl bit is used to indicate etr mode vs. pps mode.
+        */
+       if (eacr.p0 && aib.esw.psc0 == etr_lpsc_pps_mode) {
+               eacr.sl = 0;
+               eacr.e0 = 1;
+               if (!etr_mode_is_pps(etr_eacr))
+                       eacr.es = 0;
+               if (!eacr.es || !eacr.p1 || aib.esw.psc1 != etr_lpsc_pps_mode)
+                       eacr.e1 = 0;
+               // FIXME: uptodate checks ?
+               else if (etr_port0_uptodate && etr_port1_uptodate)
+                       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;
+               eacr.e1 = 1;
+               if (!etr_mode_is_pps(etr_eacr))
+                       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;
+               if (!etr_mode_is_etr(etr_eacr))
+                       eacr.es = 0;
+               if (!eacr.es || !eacr.p1 ||
+                   aib.esw.psc1 != etr_lpsc_operational_alt)
+                       eacr.e1 = 0;
+               else if (etr_port0_uptodate && etr_port1_uptodate &&
+                        etr_compare_network(&etr_port0, &etr_port1))
+                       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;
+               eacr.e1 = 1;
+               if (!etr_mode_is_etr(etr_eacr))
+                       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);
+       }
+
+       /*
+        * 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) {
+               etr_update_eacr(eacr);
+               etr_set_tolec_timeout(now);
+               return;
+       }
+
+       /*
+        * Prepare control register for clock syncing
+        * (reset data port bit, set sync check control.
+        */
+       eacr.dp = 0;
+       eacr.es = 1;
+
+       /*
+        * Update eacr and try to synchronize the clock. If the update
+        * of eacr caused a stepping port switch (or if we have to
+        * assume that a stepping port switch has occured) or the
+        * clock syncing failed, reset the sync check control bit
+        * and set up a timer to try again after 0.5 seconds
+        */
+       etr_update_eacr(eacr);
+       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);
+               etr_set_sync_timeout();
+       } else
+               etr_set_tolec_timeout(now);
+}
+
+/*
+ * Sysfs interface functions
+ */
+static struct sysdev_class etr_sysclass = {
+       set_kset_name("etr")
+};
+
+static struct sys_device etr_port0_dev = {
+       .id     = 0,
+       .cls    = &etr_sysclass,
+};
+
+static struct sys_device etr_port1_dev = {
+       .id     = 1,
+       .cls    = &etr_sysclass,
+};
+
+/*
+ * ETR class attributes
+ */
+static ssize_t etr_stepping_port_show(struct sysdev_class *class, char *buf)
+{
+       return sprintf(buf, "%i\n", etr_port0.esw.p);
+}
+
+static SYSDEV_CLASS_ATTR(stepping_port, 0400, etr_stepping_port_show, NULL);
+
+static ssize_t etr_stepping_mode_show(struct sysdev_class *class, char *buf)
+{
+       char *mode_str;
+
+       if (etr_mode_is_pps(etr_eacr))
+               mode_str = "pps";
+       else if (etr_mode_is_etr(etr_eacr))
+               mode_str = "etr";
+       else
+               mode_str = "local";
+       return sprintf(buf, "%s\n", mode_str);
+}
+
+static SYSDEV_CLASS_ATTR(stepping_mode, 0400, etr_stepping_mode_show, NULL);
+
+/*
+ * ETR port attributes
+ */
+static inline struct etr_aib *etr_aib_from_dev(struct sys_device *dev)
+{
+       if (dev == &etr_port0_dev)
+               return etr_port0_online ? &etr_port0 : NULL;
+       else
+               return etr_port1_online ? &etr_port1 : NULL;
+}
+
+static ssize_t etr_online_show(struct sys_device *dev, char *buf)
+{
+       unsigned int online;
+
+       online = (dev == &etr_port0_dev) ? etr_port0_online : etr_port1_online;
+       return sprintf(buf, "%i\n", online);
+}
+
+static ssize_t etr_online_store(struct sys_device *dev,
+                             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(ETR_FLAG_ENOSYS, &etr_flags))
+               return -ENOSYS;
+       if (dev == &etr_port0_dev) {
+               if (etr_port0_online == value)
+                       return count;   /* Nothing to do. */
+               etr_port0_online = value;
+               set_bit(ETR_EVENT_PORT0_CHANGE, &etr_events);
+               tasklet_hi_schedule(&etr_tasklet);
+       } else {
+               if (etr_port1_online == value)
+                       return count;   /* Nothing to do. */
+               etr_port1_online = value;
+               set_bit(ETR_EVENT_PORT1_CHANGE, &etr_events);
+               tasklet_hi_schedule(&etr_tasklet);
+       }
+       return count;
+}
+
+static SYSDEV_ATTR(online, 0600, etr_online_show, etr_online_store);
+
+static ssize_t etr_stepping_control_show(struct sys_device *dev, char *buf)
+{
+       return sprintf(buf, "%i\n", (dev == &etr_port0_dev) ?
+                      etr_eacr.e0 : etr_eacr.e1);
+}
+
+static SYSDEV_ATTR(stepping_control, 0400, etr_stepping_control_show, NULL);
+
+static ssize_t etr_mode_code_show(struct sys_device *dev, char *buf)
+{
+       if (!etr_port0_online && !etr_port1_online)
+               /* Status word is not uptodate if both ports are offline. */
+               return -ENODATA;
+       return sprintf(buf, "%i\n", (dev == &etr_port0_dev) ?
+                      etr_port0.esw.psc0 : etr_port0.esw.psc1);
+}
+
+static SYSDEV_ATTR(state_code, 0400, etr_mode_code_show, NULL);
+
+static ssize_t etr_untuned_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v1)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf1.u);
+}
+
+static SYSDEV_ATTR(untuned, 0400, etr_untuned_show, NULL);
+
+static ssize_t etr_network_id_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v1)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf1.net_id);
+}
+
+static SYSDEV_ATTR(network, 0400, etr_network_id_show, NULL);
+
+static ssize_t etr_id_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v1)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf1.etr_id);
+}
+
+static SYSDEV_ATTR(id, 0400, etr_id_show, NULL);
+
+static ssize_t etr_port_number_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v1)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf1.etr_pn);
+}
+
+static SYSDEV_ATTR(port, 0400, etr_port_number_show, NULL);
+
+static ssize_t etr_coupled_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v3)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf3.c);
+}
+
+static SYSDEV_ATTR(coupled, 0400, etr_coupled_show, NULL);
+
+static ssize_t etr_local_time_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v3)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf3.blto);
+}
+
+static SYSDEV_ATTR(local_time, 0400, etr_local_time_show, NULL);
+
+static ssize_t etr_utc_offset_show(struct sys_device *dev, char *buf)
+{
+       struct etr_aib *aib = etr_aib_from_dev(dev);
+
+       if (!aib || !aib->slsw.v3)
+               return -ENODATA;
+       return sprintf(buf, "%i\n", aib->edf3.buo);
+}
+
+static SYSDEV_ATTR(utc_offset, 0400, etr_utc_offset_show, NULL);
+
+static struct sysdev_attribute *etr_port_attributes[] = {
+       &attr_online,
+       &attr_stepping_control,
+       &attr_state_code,
+       &attr_untuned,
+       &attr_network,
+       &attr_id,
+       &attr_port,
+       &attr_coupled,
+       &attr_local_time,
+       &attr_utc_offset,
+       NULL
+};
+
+static int __init etr_register_port(struct sys_device *dev)
+{
+       struct sysdev_attribute **attr;
+       int rc;
+
+       rc = sysdev_register(dev);
+       if (rc)
+               goto out;
+       for (attr = etr_port_attributes; *attr; attr++) {
+               rc = sysdev_create_file(dev, *attr);
+               if (rc)
+                       goto out_unreg;
+       }
+       return 0;
+out_unreg:
+       for (; attr >= etr_port_attributes; attr--)
+               sysdev_remove_file(dev, *attr);
+       sysdev_unregister(dev);
+out:
+       return rc;
+}
+
+static void __init etr_unregister_port(struct sys_device *dev)
+{
+       struct sysdev_attribute **attr;
+
+       for (attr = etr_port_attributes; *attr; attr++)
+               sysdev_remove_file(dev, *attr);
+       sysdev_unregister(dev);
+}
+
+static int __init etr_init_sysfs(void)
+{
+       int rc;
+
+       rc = sysdev_class_register(&etr_sysclass);
+       if (rc)
+               goto out;
+       rc = sysdev_class_create_file(&etr_sysclass, &attr_stepping_port);
+       if (rc)
+               goto out_unreg_class;
+       rc = sysdev_class_create_file(&etr_sysclass, &attr_stepping_mode);
+       if (rc)
+               goto out_remove_stepping_port;
+       rc = etr_register_port(&etr_port0_dev);
+       if (rc)
+               goto out_remove_stepping_mode;
+       rc = etr_register_port(&etr_port1_dev);
+       if (rc)
+               goto out_remove_port0;
+       return 0;
+
+out_remove_port0:
+       etr_unregister_port(&etr_port0_dev);
+out_remove_stepping_mode:
+       sysdev_class_remove_file(&etr_sysclass, &attr_stepping_mode);
+out_remove_stepping_port:
+       sysdev_class_remove_file(&etr_sysclass, &attr_stepping_port);
+out_unreg_class:
+       sysdev_class_unregister(&etr_sysclass);
+out:
+       return rc;
 }
 
+device_initcall(etr_init_sysfs);
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 01f3d29..9d5b028 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -524,16 +524,15 @@ EXPORT_SYMBOL(del_virt_timer);
 void init_cpu_vtimer(void)
 {
        struct vtimer_queue *vt_list;
-       unsigned long cr0;
 
        /* kick the virtual timer */
        S390_lowcore.exit_timer = VTIMER_MAX_SLICE;
        S390_lowcore.last_update_timer = VTIMER_MAX_SLICE;
        asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));
        asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));
-       __ctl_store(cr0, 0, 0);
-       cr0 |= 0x400;
-       __ctl_load(cr0, 0, 0);
+
+       /* enable cpu timer interrupts */
+       __ctl_set_bit(0,10);
 
        vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
        INIT_LIST_HEAD(&vt_list->list);
@@ -572,6 +571,7 @@ void __init vtime_init(void)
        if (register_idle_notifier(&vtimer_idle_nb))
                panic("Couldn't register idle notifier");
 
+       /* Enable cpu timer interrupts on the boot cpu. */
        init_cpu_vtimer();
 }
 
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index 027c474..0285444 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -1,5 +1,5 @@
 /*
- *  arch/s390/kernel/delay.c
+ *  arch/s390/lib/delay.c
  *    Precise Delay Loops for S390
  *
  *  S390 version
@@ -13,10 +13,8 @@
 
 #include <linux/sched.h>
 #include <linux/delay.h>
-
-#ifdef CONFIG_SMP
-#include <asm/smp.h>
-#endif
+#include <linux/timex.h>
+#include <linux/irqflags.h>
 
 void __delay(unsigned long loops)
 {
@@ -31,17 +29,39 @@ void __delay(unsigned long loops)
 }
 
 /*
- * Waits for 'usecs' microseconds using the tod clock, giving up the time slice
- * of the virtual PU inbetween to avoid congestion.
+ * Waits for 'usecs' microseconds using the TOD clock comparator.
  */
 void __udelay(unsigned long usecs)
 {
-       uint64_t start_cc;
+       u64 end, time, jiffy_timer = 0;
+       unsigned long flags, cr0, mask, dummy;
+
+       local_irq_save(flags);
+       if (raw_irqs_disabled_flags(flags)) {
+               jiffy_timer = S390_lowcore.jiffy_timer;
+               S390_lowcore.jiffy_timer = -1ULL - (4096 << 12);
+               __ctl_store(cr0, 0, 0);
+               dummy = (cr0 & 0xffff00e0) | 0x00000800;
+               __ctl_load(dummy , 0, 0);
+               mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
+       } else
+               mask = psw_kernel_bits | PSW_MASK_WAIT |
+                       PSW_MASK_EXT | PSW_MASK_IO;
+
+       end = get_clock() + ((u64) usecs << 12);
+       do {
+               time = end < S390_lowcore.jiffy_timer ?
+                       end : S390_lowcore.jiffy_timer;
+               set_clock_comparator(time);
+               trace_hardirqs_on();
+               __load_psw_mask(mask);
+               local_irq_disable();
+       } while (get_clock() < end);
 
-        if (usecs == 0)
-                return;
-       start_cc = get_clock();
-        do {
-               cpu_relax();
-       } while (((get_clock() - start_cc)/4096) < usecs);
+       if (raw_irqs_disabled_flags(flags)) {
+               __ctl_load(cr0, 0, 0);
+               S390_lowcore.jiffy_timer = jiffy_timer;
+       }
+       set_clock_comparator(S390_lowcore.jiffy_timer);
+       local_irq_restore(flags);
 }
diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index f208940..555e18a 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1232,6 +1232,19 @@ __dasd_process_blk_queue(struct dasd_device * device)
                if (IS_ERR(cqr)) {
                        if (PTR_ERR(cqr) == -ENOMEM)
                                break;  /* terminate request queue loop */
+                       if (PTR_ERR(cqr) == -EAGAIN) {
+                               /*
+                                * The current request cannot be build right
+                                * now, we have to try later. If this request
+                                * is the head-of-queue we stop the device
+                                * for 1/2 second.
+                                */
+                               if (!list_empty(&device->ccw_queue))
+                                       break;
+                               device->stopped |= DASD_STOPPED_PENDING;
+                               dasd_set_timer(device, HZ/2);
+                               break;
+                       }
                        DBF_DEV_EVENT(DBF_ERR, device,
                                      "CCW creation failed (rc=%ld) "
                                      "on request %p",
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index d59115c..a17d731 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -204,37 +204,39 @@ recs_per_track(struct dasd_eckd_characteristics * rdc,
        return 0;
 }
 
-static inline void
+static inline int
 check_XRC (struct ccw1         *de_ccw,
            struct DE_eckd_data *data,
            struct dasd_device  *device)
 {
         struct dasd_eckd_private *private;
+       int rc;
 
         private = (struct dasd_eckd_private *) device->private;
+       if (!private->rdc_data.facilities.XRC_supported)
+               return 0;
 
         /* switch on System Time Stamp - needed for XRC Support */
-        if (private->rdc_data.facilities.XRC_supported) {
-
-                data->ga_extended |= 0x08; /* switch on 'Time Stamp Valid'   */
-                data->ga_extended |= 0x02; /* switch on 'Extended Parameter' */
-
-                data->ep_sys_time = get_clock ();
-
-                de_ccw->count = sizeof (struct DE_eckd_data);
-               de_ccw->flags |= CCW_FLAG_SLI;
-        }
+       data->ga_extended |= 0x08; /* switch on 'Time Stamp Valid'   */
+       data->ga_extended |= 0x02; /* switch on 'Extended Parameter' */
 
-        return;
+       rc = get_sync_clock(&data->ep_sys_time);
+       /* Ignore return code if sync clock is switched off. */
+       if (rc == -ENOSYS || rc == -EACCES)
+               rc = 0;
 
-} /* end check_XRC */
+       de_ccw->count = sizeof (struct DE_eckd_data);
+       de_ccw->flags |= CCW_FLAG_SLI;
+       return rc;
+}
 
-static inline void
+static inline int
 define_extent(struct ccw1 * ccw, struct DE_eckd_data * data, int trk,
              int totrk, int cmd, struct dasd_device * device)
 {
        struct dasd_eckd_private *private;
        struct ch_t geo, beg, end;
+       int rc = 0;
 
        private = (struct dasd_eckd_private *) device->private;
 
@@ -263,12 +265,12 @@ define_extent(struct ccw1 * ccw, struct DE_eckd_data * 
data, int trk,
        case DASD_ECKD_CCW_WRITE_KD_MT:
                data->mask.perm = 0x02;
                data->attributes.operation = private->attrib.operation;
-                check_XRC (ccw, data, device);
+               rc = check_XRC (ccw, data, device);
                break;
        case DASD_ECKD_CCW_WRITE_CKD:
        case DASD_ECKD_CCW_WRITE_CKD_MT:
                data->attributes.operation = DASD_BYPASS_CACHE;
-                check_XRC (ccw, data, device);
+               rc = check_XRC (ccw, data, device);
                break;
        case DASD_ECKD_CCW_ERASE:
        case DASD_ECKD_CCW_WRITE_HOME_ADDRESS:
@@ -276,7 +278,7 @@ define_extent(struct ccw1 * ccw, struct DE_eckd_data * 
data, int trk,
                data->mask.perm = 0x3;
                data->mask.auth = 0x1;
                data->attributes.operation = DASD_BYPASS_CACHE;
-                check_XRC (ccw, data, device);
+               rc = check_XRC (ccw, data, device);
                break;
        default:
                DEV_MESSAGE(KERN_ERR, device, "unknown opcode 0x%x", cmd);
@@ -312,6 +314,7 @@ define_extent(struct ccw1 * ccw, struct DE_eckd_data * 
data, int trk,
        data->beg_ext.head = beg.head;
        data->end_ext.cyl = end.cyl;
        data->end_ext.head = end.head;
+       return rc;
 }
 
 static inline void
@@ -1200,7 +1203,12 @@ dasd_eckd_build_cp(struct dasd_device * device, struct 
request *req)
                return cqr;
        ccw = cqr->cpaddr;
        /* First ccw is define extent. */
-       define_extent(ccw++, cqr->data, first_trk, last_trk, cmd, device);
+       if (define_extent(ccw++, cqr->data, first_trk,
+                         last_trk, cmd, device) == -EAGAIN) {
+               /* Clock not in sync and XRC is enabled. Try again later. */
+               dasd_sfree_request(cqr, device);
+               return ERR_PTR(-EAGAIN);
+       }
        /* Build locate_record+read/write/ccws. */
        idaws = (unsigned long *) (cqr->data + sizeof(struct DE_eckd_data));
        LO_data = (struct LO_eckd_data *) (idaws + cidaw);
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 07a4cbf..ad2b379 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -646,7 +646,7 @@ do_IRQ (struct pt_regs *regs)
                 * Make sure that the i/o interrupt did not "overtake"
                 * the last HZ timer interrupt.
                 */
-               account_ticks();
+               account_ticks(S390_lowcore.int_clock);
        /*
         * Get interrupt information from lowcore
         */
@@ -850,6 +850,19 @@ __disable_subchannel_easy(struct subchannel_id schid, 
struct schib *schib)
        return -EBUSY; /* uhm... */
 }
 
+/* we can't use the normal udelay here, since it enables external interrupts */
+
+static void udelay_reset(unsigned long usecs)
+{
+       uint64_t start_cc, end_cc;
+
+       asm volatile ("STCK %0" : "=m" (start_cc));
+       do {
+               cpu_relax();
+               asm volatile ("STCK %0" : "=m" (end_cc));
+       } while (((end_cc - start_cc)/4096) < usecs);
+}
+
 static inline int
 __clear_subchannel_easy(struct subchannel_id schid)
 {
@@ -865,7 +878,7 @@ __clear_subchannel_easy(struct subchannel_id schid)
                        if (schid_equal(&ti.schid, &schid))
                                return 0;
                }
-               udelay(100);
+               udelay_reset(100);
        }
        return -EBUSY;
 }
diff --git a/drivers/s390/s390mach.c b/drivers/s390/s390mach.c
index 442d634..806bb1a 100644
--- a/drivers/s390/s390mach.c
+++ b/drivers/s390/s390mach.c
@@ -15,7 +15,7 @@
 #include <linux/time.h>
 #include <linux/device.h>
 #include <linux/kthread.h>
-
+#include <asm/etr.h>
 #include <asm/lowcore.h>
 #include <asm/cio.h>
 #include "cio/cio.h"
@@ -466,6 +466,19 @@ s390_do_machine_check(struct pt_regs *regs)
                        s390_handle_damage("unable to revalidate registers.");
        }
 
+       if (mci->cd) {
+               /* Timing facility damage */
+               s390_handle_damage("TOD clock damaged");
+       }
+
+       if (mci->ed && mci->ec) {
+               /* External damage */
+               if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
+                       etr_sync_check();
+               if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
+                       etr_switch_to_local();
+       }
+
        if (mci->se)
                /* Storage error uncorrected */
                s390_handle_damage("received storage error uncorrected "
@@ -504,7 +517,7 @@ static int
 machine_check_init(void)
 {
        init_MUTEX_LOCKED(&m_sem);
-       ctl_clear_bit(14, 25);  /* disable external damage MCH */
+       ctl_set_bit(14, 25);    /* enable external damage MCH */
        ctl_set_bit(14, 27);    /* enable system recovery MCH */
 #ifdef CONFIG_MACHCHK_WARNING
        ctl_set_bit(14, 24);    /* enable warning MCH */
diff --git a/drivers/s390/s390mach.h b/drivers/s390/s390mach.h
index 7abb42a..d3ca428 100644
--- a/drivers/s390/s390mach.h
+++ b/drivers/s390/s390mach.h
@@ -102,4 +102,7 @@ static inline int stcrw(struct crw *pcrw )
        return ccode;
 }
 
+#define ED_ETR_SYNC    12      /* External damage ETR sync check */
+#define ED_ETR_SWITCH  13      /* External damage ETR switch to local */
+
 #endif /* __s390mach */
diff --git a/include/asm-s390/etr.h b/include/asm-s390/etr.h
new file mode 100644
index 0000000..b498f19
--- /dev/null
+++ b/include/asm-s390/etr.h
@@ -0,0 +1,219 @@
+/*
+ *  include/asm-s390/etr.h
+ *
+ *  Copyright IBM Corp. 2006
+ *  Author(s): Martin Schwidefsky ([EMAIL PROTECTED])
+ */
+#ifndef __S390_ETR_H
+#define __S390_ETR_H
+
+/* ETR attachment control register */
+struct etr_eacr {
+       unsigned int e0         : 1;    /* port 0 stepping control */
+       unsigned int e1         : 1;    /* port 1 stepping control */
+       unsigned int _pad0      : 5;    /* must be 00100 */
+       unsigned int dp         : 1;    /* data port control */
+       unsigned int p0         : 1;    /* port 0 change recognition control */
+       unsigned int p1         : 1;    /* port 1 change recognition control */
+       unsigned int _pad1      : 3;    /* must be 000 */
+       unsigned int ea         : 1;    /* ETR alert control */
+       unsigned int es         : 1;    /* ETR sync check control */
+       unsigned int sl         : 1;    /* switch to local control */
+} __attribute__ ((packed));
+
+/* Port state returned by steai */
+enum etr_psc {
+       etr_psc_operational = 0,
+       etr_psc_semi_operational = 1,
+       etr_psc_protocol_error =  4,
+       etr_psc_no_symbols = 8,
+       etr_psc_no_signal = 12,
+       etr_psc_pps_mode = 13
+};
+
+/* Logical port state returned by stetr */
+enum etr_lpsc {
+       etr_lpsc_operational_step = 0,
+       etr_lpsc_operational_alt = 1,
+       etr_lpsc_semi_operational = 2,
+       etr_lpsc_protocol_error =  4,
+       etr_lpsc_no_symbol_sync = 8,
+       etr_lpsc_no_signal = 12,
+       etr_lpsc_pps_mode = 13
+};
+
+/* ETR status words */
+struct etr_esw {
+       struct etr_eacr eacr;           /* attachment control register */
+       unsigned int y          : 1;    /* stepping mode */
+       unsigned int _pad0      : 5;    /* must be 00000 */
+       unsigned int p          : 1;    /* stepping port number */
+       unsigned int q          : 1;    /* data port number */
+       unsigned int psc0       : 4;    /* port 0 state code */
+       unsigned int psc1       : 4;    /* port 1 state code */
+} __attribute__ ((packed));
+
+/* Second level data register status word */
+struct etr_slsw {
+       unsigned int vv1        : 1;    /* copy of validity bit data frame 1 */
+       unsigned int vv2        : 1;    /* copy of validity bit data frame 2 */
+       unsigned int vv3        : 1;    /* copy of validity bit data frame 3 */
+       unsigned int vv4        : 1;    /* copy of validity bit data frame 4 */
+       unsigned int _pad0      : 19;   /* must by all zeroes */
+       unsigned int n          : 1;    /* EAF port number */
+       unsigned int v1         : 1;    /* validity bit ETR data frame 1 */
+       unsigned int v2         : 1;    /* validity bit ETR data frame 2 */
+       unsigned int v3         : 1;    /* validity bit ETR data frame 3 */
+       unsigned int v4         : 1;    /* validity bit ETR data frame 4 */
+       unsigned int _pad1      : 4;    /* must be 0000 */
+} __attribute__ ((packed));
+
+/* ETR data frames */
+struct etr_edf1 {
+       unsigned int u          : 1;    /* untuned bit */
+       unsigned int _pad0      : 1;    /* must be 0 */
+       unsigned int r          : 1;    /* service request bit */
+       unsigned int _pad1      : 4;    /* must be 0000 */
+       unsigned int a          : 1;    /* time adjustment bit */
+       unsigned int net_id     : 8;    /* ETR network id */
+       unsigned int etr_id     : 8;    /* id of ETR which sends data frames */
+       unsigned int etr_pn     : 8;    /* port number of ETR output port */
+} __attribute__ ((packed));
+
+struct etr_edf2 {
+       unsigned int etv        : 32;   /* Upper 32 bits of TOD. */
+} __attribute__ ((packed));
+
+struct etr_edf3 {
+       unsigned int rc         : 8;    /* failure reason code */
+       unsigned int _pad0      : 3;    /* must be 000 */
+       unsigned int c          : 1;    /* ETR coupled bit */
+       unsigned int tc         : 4;    /* ETR type code */
+       unsigned int blto       : 8;    /* biased local time offset */
+                                       /* (blto - 128) * 15 = minutes */
+       unsigned int buo        : 8;    /* biased utc offset */
+                                       /* (buo - 128) = leap seconds */
+} __attribute__ ((packed));
+
+struct etr_edf4 {
+       unsigned int ed         : 8;    /* ETS device dependent data */
+       unsigned int _pad0      : 1;    /* must be 0 */
+       unsigned int buc        : 5;    /* biased ut1 correction */
+                                       /* (buc - 16) * 0.1 seconds */
+       unsigned int em         : 6;    /* ETS error magnitude */
+       unsigned int dc         : 6;    /* ETS drift code */
+       unsigned int sc         : 6;    /* ETS steering code */
+} __attribute__ ((packed));
+
+/*
+ * ETR attachment information block, two formats
+ * format 1 has 4 reserved words with a size of 64 bytes
+ * format 2 has 16 reserved words with a size of 96 bytes
+ */
+struct etr_aib {
+       struct etr_esw esw;
+       struct etr_slsw slsw;
+       unsigned long long tsp;
+       struct etr_edf1 edf1;
+       struct etr_edf2 edf2;
+       struct etr_edf3 edf3;
+       struct etr_edf4 edf4;
+       unsigned int reserved[16];
+} __attribute__ ((packed,aligned(8)));
+
+/* ETR interruption parameter */
+struct etr_interruption_parameter {
+       unsigned int _pad0      : 8;
+       unsigned int pc0        : 1;    /* port 0 state change */
+       unsigned int pc1        : 1;    /* port 1 state change */
+       unsigned int _pad1      : 3;
+       unsigned int eai        : 1;    /* ETR alert indication */
+       unsigned int _pad2      : 18;
+} __attribute__ ((packed));
+
+/* Query TOD offset result */
+struct etr_ptff_qto {
+       unsigned long long physical_clock;
+       unsigned long long tod_offset;
+       unsigned long long logical_tod_offset;
+       unsigned long long tod_epoch_difference;
+} __attribute__ ((packed));
+
+/* Inline assembly helper functions */
+static inline int etr_setr(struct etr_eacr *ctrl)
+{
+       int rc = -ENOSYS;
+
+       asm volatile(
+               "       .insn   s,0xb2160000,0(%2)\n"
+               "0:     la      %0,0\n"
+               "1:\n"
+               EX_TABLE(0b,1b)
+               : "+d" (rc) : "m" (*ctrl), "a" (ctrl));
+       return rc;
+}
+
+/* Stores a format 1 aib with 64 bytes */
+static inline int etr_stetr(struct etr_aib *aib)
+{
+       int rc = -ENOSYS;
+
+       asm volatile(
+               "       .insn   s,0xb2170000,0(%2)\n"
+               "0:     la      %0,0\n"
+               "1:\n"
+               EX_TABLE(0b,1b)
+               : "+d" (rc) : "m" (*aib), "a" (aib));
+       return rc;
+}
+
+/* Stores a format 2 aib with 96 bytes for specified port */
+static inline int etr_steai(struct etr_aib *aib, unsigned int func)
+{
+       register unsigned int reg0 asm("0") = func;
+       int rc = -ENOSYS;
+
+       asm volatile(
+               "       .insn   s,0xb2b30000,0(%2)\n"
+               "0:     la      %0,0\n"
+               "1:\n"
+               EX_TABLE(0b,1b)
+               : "+d" (rc) : "m" (*aib), "a" (aib), "d" (reg0));
+       return rc;
+}
+
+/* Function codes for the steai instruction. */
+#define ETR_STEAI_STEPPING_PORT                0x10
+#define ETR_STEAI_ALTERNATE_PORT       0x11
+#define ETR_STEAI_PORT_0               0x12
+#define ETR_STEAI_PORT_1               0x13
+
+static inline int etr_ptff(void *ptff_block, unsigned int func)
+{
+       register unsigned int reg0 asm("0") = func;
+       register unsigned long reg1 asm("1") = (unsigned long) ptff_block;
+       int rc = -ENOSYS;
+
+       asm volatile(
+               "       .word   0x0104\n"
+               "       ipm     %0\n"
+               "       srl     %0,28\n"
+               : "=d" (rc), "=m" (ptff_block)
+               : "d" (reg0), "d" (reg1), "m" (ptff_block) : "cc");
+       return rc;
+}
+
+/* Function codes for the ptff instruction. */
+#define ETR_PTFF_QAF   0x00    /* query available functions */
+#define ETR_PTFF_QTO   0x01    /* query tod offset */
+#define ETR_PTFF_QSI   0x02    /* query steering information */
+#define ETR_PTFF_ATO   0x40    /* adjust tod offset */
+#define ETR_PTFF_STO   0x41    /* set tod offset */
+#define ETR_PTFF_SFS   0x42    /* set fine steering rate */
+#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);
+
+#endif /* __S390_ETR_H */
diff --git a/include/asm-s390/hardirq.h b/include/asm-s390/hardirq.h
index c2f6a87..31beb18 100644
--- a/include/asm-s390/hardirq.h
+++ b/include/asm-s390/hardirq.h
@@ -32,6 +32,6 @@ typedef struct {
 
 #define HARDIRQ_BITS   8
 
-extern void account_ticks(void);
+extern void account_ticks(u64 time);
 
 #endif /* __ASM_HARDIRQ_H */
diff --git a/include/asm-s390/timex.h b/include/asm-s390/timex.h
index 9ee5d80..5cbd55c 100644
--- a/include/asm-s390/timex.h
+++ b/include/asm-s390/timex.h
@@ -11,6 +11,41 @@
 #ifndef _ASM_S390_TIMEX_H
 #define _ASM_S390_TIMEX_H
 
+/* Inline functions for clock register access. */
+static inline int set_clock(__u64 time)
+{
+       int cc;
+
+       asm volatile(
+               "   sck   0(%2)\n"
+               "   ipm   %0\n"
+               "   srl   %0,28\n"
+               : "=d" (cc) : "m" (time), "a" (&time) : "cc");
+       return cc;
+}
+
+static inline int store_clock(__u64 *time)
+{
+       int cc;
+
+       asm volatile(
+               "   stck  0(%2)\n"
+               "   ipm   %0\n"
+               "   srl   %0,28\n"
+               : "=d" (cc), "=m" (*time) : "a" (time) : "cc");
+       return cc;
+}
+
+static inline void set_clock_comparator(__u64 time)
+{
+       asm volatile("sckc 0(%1)" : : "m" (time), "a" (&time));
+}
+
+static inline void store_clock_comparator(__u64 *time)
+{
+       asm volatile("stckc 0(%1)" : "=m" (*time) : "a" (time));
+}
+
 #define CLOCK_TICK_RATE        1193180 /* Underlying HZ */
 
 typedef unsigned long long cycles_t;
@@ -32,6 +67,7 @@ static inline cycles_t get_cycles(void)
        return (cycles_t) get_clock() >> 2;
 }
 
+int get_sync_clock(unsigned long long *clock);
 void init_cpu_timer(void);
 
 #endif
-
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