[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 <schwidefsky@de.ibm.com>
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 @@
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 @@
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->ga_extended |= 0x08; /* switch on 'Time Stamp Valid' */
- data->ga_extended |= 0x02; /* switch on 'Extended Parameter' */
+ rc = get_sync_clock(&data->ep_sys_time);
+ /* Ignore return code if sync clock is switched off. */
+ if (rc == -ENOSYS || rc == -EACCES)
+ rc = 0;
- data->ep_sys_time = get_clock ();
+ de_ccw->count = sizeof (struct DE_eckd_data);
+ de_ccw->flags |= CCW_FLAG_SLI;
+ return rc;
+}
- de_ccw->count = sizeof (struct DE_eckd_data);
- de_ccw->flags |= CCW_FLAG_SLI;
- }
-
- return;
-
-} /* end check_XRC */
-
-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 @@
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 @@
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 @@
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 @@
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 @@
* 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 @@
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 @@
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_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 @@
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 @@
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 */