On 25/03/2021 10.39, Pierre Morel wrote:
Some tests require to disable a subchannel.
Let's implement the css_disable() function.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
lib/s390x/css.h | 1 +
lib/s390x/css_lib.c | 67 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 68 insertions(+)
diff --git a/lib/s390x/css.h b/lib/s390x/css.h
index 7e3d261..b0de3a3 100644
--- a/lib/s390x/css.h
+++ b/lib/s390x/css.h
@@ -284,6 +284,7 @@ int css_enumerate(void);
#define IO_SCH_ISC 3
int css_enable(int schid, int isc);
bool css_enabled(int schid);
+int css_disable(int schid);
/* Library functions */
int start_ccw1_chain(unsigned int sid, struct ccw1 *ccw);
diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
index efc7057..f5c4f37 100644
--- a/lib/s390x/css_lib.c
+++ b/lib/s390x/css_lib.c
@@ -186,6 +186,73 @@ bool css_enabled(int schid)
}
return true;
}
+
+/*
+ * css_disable: disable the subchannel
+ * @schid: Subchannel Identifier
+ * Return value:
+ * On success: 0
+ * On error the CC of the faulty instruction
+ * or -1 if the retry count is exceeded.
+ */
+int css_disable(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: sch %08x failed with cc=%d", schid, cc);
+ return cc;
+ }
+
+ if (!(pmcw->flags & PMCW_ENABLE)) {
+ report_info("stsch: sch %08x already disabled", schid);
+ return 0;
+ }
+
+retry:
I have to saythat I really dislike writing loops with gotos if it can be
avoided easily. What about:
for (retry_count = 0; retry_count < MAX_ENABLE_RETRIES; retry_count++) ?
(and maybe rename that variable to "retries" to keep it short?)
+ /* Update the SCHIB to disable the subchannel */
+ pmcw->flags &= ~PMCW_ENABLE;
+
+ /* Tell the CSS we want to modify the subchannel */
+ cc = msch(schid, &schib);
+ /*
+ * If the subchannel is status pending or if a function is in progress,
+ * we consider both cases as errors.
+ */
+ if (cc) {
+ report_info("msch: sch %08x failed with cc=%d", schid, cc);
+ return cc;
+ }
+
+ /* Read the SCHIB again to verify the enablement */
"verify the disablement" ?
+ cc = stsch(schid, &schib);
+ if (cc) {
+ report_info("stsch: updating sch %08x failed with cc=%d",
+ schid, cc);
+ return cc;
+ }
+
+ if (!(pmcw->flags & PMCW_ENABLE)) {
+ if (retry_count)
+ report_info("stsch: sch %08x successfully disabled after %d retries",
+ schid, retry_count);
+ return 0;
+ }
+
+ if (retry_count++ < MAX_ENABLE_RETRIES) {
+ /* the hardware was not ready, give it some time */
+ mdelay(10);
+ goto retry;
+ }
+
+ report_info("msch: modifying sch %08x failed after %d retries. pmcw flags: %04x",
+ schid, retry_count, pmcw->flags);
+ return -1;
+}
/*
* css_enable: enable the subchannel with the specified ISC
* @schid: Subchannel Identifier
Thomas
