A second step when testing the channel subsystem is to prepare a channel
for use.
This includes:
- Get the current subchannel Information Block (SCHIB) using STSCH
- Update it in memory to set the ENABLE bit
- Tell the CSS that the SCHIB has been modified using MSCH
- Get the SCHIB from the CSS again to verify that the subchannel is
enabled.
- If the command succeeds but subchannel is not enabled retry a
predefined retries count.
- If the command fails, report the failure and do not retry, even
if cc indicates a busy/status pending as we do not expect this.
This tests the MSCH instruction to enable a channel succesfuly.
This some retries are done and in case of error, and if the retries
count is exceeded, a report is made.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
lib/s390x/css_lib.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
s390x/css.c | 18 ++++++++++++++
2 files changed, 78 insertions(+)
diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
index dc5a512..831a116 100644
--- a/lib/s390x/css_lib.c
+++ b/lib/s390x/css_lib.c
@@ -15,6 +15,7 @@
#include <string.h>
#include <interrupt.h>
#include <asm/arch_def.h>
+#include <asm/time.h>
#include <css.h>
@@ -68,3 +69,62 @@ out:
scn, scn_found, dev_found);
return schid;
}
+
+int css_enable(int schid)
+{
+ struct pmcw *pmcw = &schib.pmcw;
+ int retry_count = 0;
+ int cc;
+
+ /* Read the SCHIB for this subchannel */
+ cc = stsch(schid, &schib);
+ if (cc) {
+ report_info("stsch failed with cc=%d", cc);
+ return cc;
+ }
+
+ if (pmcw->flags & PMCW_ENABLE) {
+ report_info("stsch: sch %08x already enabled", schid);
+ return 0;
+ }
+
+retry:
+ /* Update the SCHIB to enable the channel */
+ pmcw->flags |= PMCW_ENABLE;
+
+ /* Tell the CSS we want to modify the subchannel */
+ cc = msch(schid, &schib);
+ if (cc) {
+ /*
+ * If the subchannel is status pending or
+ * if a function is in progress,
+ * we consider both cases as errors.
+ */
+ report_info("msch failed with cc=%d", cc);
+ return cc;
+ }
+
+ /*
+ * Read the SCHIB again to verify the enablement
+ */
+ cc = stsch(schid, &schib);
+ if (cc) {
+ report_info("stsch failed with cc=%d", cc);
+ return cc;
+ }
+
+ if (pmcw->flags & PMCW_ENABLE) {
+ report_info("Subchannel %08x enabled after %d retries",
+ schid, retry_count);
+ return 0;
+ }
+
+ if (retry_count++ < MAX_ENABLE_RETRIES) {
+ mdelay(10); /* the hardware was not ready, give it some time */
+ goto retry;
+ }
+
+ report_info("msch: enabling sch %08x failed after %d retries. pmcw flags: %x",
+ schid, retry_count, pmcw->flags);
+ return -1;
+}
diff --git a/s390x/css.c b/s390x/css.c
index f0e8f47..6f58d4a 100644
--- a/s390x/css.c
+++ b/s390x/css.c
@@ -40,11 +40,29 @@ static void test_enumerate(void)
}
}
+static void test_enable(void)
+{
+ int cc;
+
+ if (!test_device_sid) {
+ report_skip("No device");
+ return;
+ }
+
+ cc = css_enable(test_device_sid);
+
+ if (cc)
+ report(0, "Failed to enable subchannel %08x", test_device_sid);
+ else
+ report(1, "Subchannel %08x enabled", test_device_sid);
