[kvm-unit-tests PATCH v2 9/9] s390x: css: ping pong

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

To test a write command with the SSCH instruction we need a QEMU device,
with control unit type 0xC0CA. The PONG device is such a device.

This type of device respond to PONG_WRITE requests by incrementing an
integer, stored as a string at offset 0 of the CCW data.

This is only a success test, no error expected.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
 s390x/css.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/s390x/css.c b/s390x/css.c
index 534864f..0761e70 100644
--- a/s390x/css.c
+++ b/s390x/css.c
@@ -23,6 +23,10 @@
 #define SID_ONE		0x00010000
 #define PSW_PRG_MASK (PSW_MASK_IO | PSW_MASK_EA | PSW_MASK_BA)
 
+/* Local Channel Commands */
+#define PONG_WRITE	0x21 /* Write */
+#define PONG_READ	0x22 /* Read buffer */
+
 struct lowcore *lowcore = (void *)0x0;
 
 static struct schib schib;
@@ -31,7 +35,8 @@ static struct ccw ccw[NB_CCW];
 #define NB_ORB  100
 static struct orb orb[NB_ORB];
 static struct irb irb;
-static char buffer[0x1000] __attribute__ ((aligned(8)));
+#define BUF_SZ	0x1000
+static char buffer[BUF_SZ] __attribute__ ((aligned(8)));
 static struct senseid senseid;
 
 static const char *Channel_type[3] = {
@@ -224,6 +229,44 @@ static void test_sense(void)
 		report("cu_type: expect c0ca, got %04x", 0, senseid.cu_type);
 }
 
+static void test_ping(void)
+{
+	int success, result;
+	int cnt = 0, max = 4;
+
+	if (senseid.cu_type != PONG_CU) {
+		report_skip("No PONG, no ping-pong");
+		return;
+	}
+
+	enable_io_irq();
+
+	while (cnt++ < max) {
+report_info("cnt..: %08x", cnt);
+		snprintf(buffer, BUF_SZ, "%08x\n", cnt);
+		success = start_subchannel(PONG_WRITE, buffer, 8);
+		if (!success) {
+			report("start_subchannel failed", 0);
+			return;
+		}
+		delay(100);
+		success = start_subchannel(PONG_READ, buffer, 8);
+		if (!success) {
+			report("start_subchannel failed", 0);
+			return;
+		}
+		result = atol(buffer);
+		if (result != (cnt + 1)) {
+			report("Bad answer from pong: %08x - %08x", 0, cnt, result);
+			return;
+		} else 
+			report_info("%08x - %08x", cnt, result);
+
+		delay(100);
+	}
+	report("ping-pong count 0x%08x", 1, cnt);
+}
+
 static struct {
 	const char *name;
 	void (*func)(void);
@@ -231,6 +274,7 @@ static struct {
 	{ "enumerate (stsch)", test_enumerate },
 	{ "enable (msch)", test_enable },
 	{ "sense (ssch/tsch)", test_sense },
+	{ "ping-pong (ssch/tsch)", test_ping },
 	{ NULL, NULL }
 };
 
-- 
2.17.0