diff --git a/s390x/css.c b/s390x/css.c
index 1c891f8..ee02cdd 100644
--- a/s390x/css.c
+++ b/s390x/css.c
@@ -51,6 +51,175 @@ static void test_enable(void)
 	report(cc == 0, "Enable subchannel %08x", test_device_sid);
 }
 
+static void dummy_irq(void)
+{
+}
+
+static int check_io_completion(int sid, uint32_t expected)
+{
+	struct irb irb;
+	int ret;
+
+	report_prefix_push("IRQ flags");
+
+	ret = tsch(sid, &irb);
+	if (ret)
+		goto end;
+
+	if (!expected)
+		goto end;
+
+	if (!(expected & irb.scsw.ctrl)) {
+		report_info("expect: %s got: %s",
+			    dump_scsw_flags(expected),
+			    dump_scsw_flags(irb.scsw.ctrl));
+		ret = -1;
+	}
+
+end:
+	report(!ret, "expectations");
+	report_prefix_pop();
+	return ret;
+}
+
+static void test_csch(void)
+{
+	struct orb orb = {
+		.intparm = test_device_sid,
+		.ctrl = ORB_CTRL_ISIC | ORB_CTRL_FMT | ORB_LPM_DFLT,
+	};
+	struct ccw1 *ccw;
+
+	senseid = alloc_io_mem(sizeof(*senseid), 0);
+	assert(senseid);
+	ccw = ccw_alloc(CCW_CMD_SENSE_ID, senseid, sizeof(*senseid), CCW_F_SLI);
+	assert(ccw);
+	orb.cpa = (uint64_t)ccw;
+
+	/* 1- Basic check for CSCH */
+	report_prefix_push("CSCH on a quiet subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	report(csch(test_device_sid) == 0, "subchannel clear");
+
+	/* now we check the flags */
+	report_prefix_push("IRQ flags");
+	report(wait_and_check_io_completion(test_device_sid, SCSW_FC_CLEAR) == 0, "expected");
+	report_prefix_pop();
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* For the following checks we need to execute tsch synchronously */
+	assert(unregister_io_int_func(css_irq_io) == 0);
+	assert(register_io_int_func(dummy_irq) == 0);
+
+	/* 2- We want to check if the IRQ flags of SSCH are erased by clear */
+	report_prefix_push("CSCH on SSCH status pending subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	assert(ssch(test_device_sid, &orb) == 0);
+	report(csch(test_device_sid) == 0, "subchannel cleared");
+	check_io_completion(test_device_sid, SCSW_FC_CLEAR);
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* 3- Checking CSCH after HSCH */
+	report_prefix_push("CSCH on a halted subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	assert(hsch(test_device_sid) == 0);
+	report(csch(test_device_sid) == 0, "subchannel cleared");
+	check_io_completion(test_device_sid, SCSW_FC_CLEAR);
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* 4- Checking CSCH after CSCH */
+	report_prefix_push("CSCH on a cleared subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	assert(csch(test_device_sid) == 0);
+	report(csch(test_device_sid) == 0, "subchannel cleared");
+	check_io_completion(test_device_sid, SCSW_FC_CLEAR);
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* Reset the IRQ handler */
+	assert(unregister_io_int_func(dummy_irq) == 0);
+	assert(register_io_int_func(css_irq_io) == 0);
+
+	free_io_mem(senseid, sizeof(*senseid));
+	free_io_mem(ccw, sizeof(*ccw));
+}
+
+static void test_hsch(void)
+{
+	struct orb orb = {
+		.intparm = test_device_sid,
+		.ctrl = ORB_CTRL_ISIC | ORB_CTRL_FMT | ORB_LPM_DFLT,
+	};
+	struct ccw1 *ccw;
+
+	senseid = alloc_io_mem(sizeof(*senseid), 0);
+	assert(senseid);
+	ccw = ccw_alloc(CCW_CMD_SENSE_ID, senseid, sizeof(*senseid), CCW_F_SLI);
+	assert(ccw);
+	orb.cpa = (uint64_t)ccw;
+
+	/* 1- Basic HSCH */
+	report_prefix_push("HSCH on a quiet subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	report(hsch(test_device_sid) == 0, "subchannel halted");
+
+	/* now we check the flags */
+	report_prefix_push("IRQ flags");
+	report(wait_and_check_io_completion(test_device_sid, SCSW_FC_HALT) == 0, "expected");
+	report_prefix_pop();
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* For the following checks we need to execute tsch synchronously */
+	assert(unregister_io_int_func(css_irq_io) == 0);
+	assert(register_io_int_func(dummy_irq) == 0);
+
+	/* 2- Check HSCH after SSCH */
+	report_prefix_push("HSCH on status pending subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	assert(ssch(test_device_sid, &orb) == 0);
+	report(hsch(test_device_sid) == 1, "Halt subchannel should fail with CC 1");
+	check_io_completion(test_device_sid, SCSW_FC_START);
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* 3- Check HSCH after CSCH */
+	report_prefix_push("HSCH on busy on CSCH subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	assert(csch(test_device_sid) == 0);
+	report(hsch(test_device_sid) == 1, "Halt subchannel should fail with CC 1");
+	check_io_completion(test_device_sid, SCSW_FC_CLEAR);
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* 4- Check HSCH after HSCH */
+	report_prefix_push("HSCH on busy on HSCH subchannel");
+	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
+	assert(hsch(test_device_sid) == 0);
+	report(hsch(test_device_sid) == 1, "Halt subchannel should fail with CC 1");
+	check_io_completion(test_device_sid, SCSW_FC_HALT);
+
+	assert(css_disable(test_device_sid) == 0);
+	report_prefix_pop();
+
+	/* Reset the IRQ handler */
+	assert(unregister_io_int_func(dummy_irq) == 0);
+	assert(register_io_int_func(css_irq_io) == 0);
+
+	free_io_mem(senseid, sizeof(*senseid));
+	free_io_mem(ccw, sizeof(*ccw));
+}
+
 static void test_ssch(void)
 {
 	struct orb orb = {
@@ -61,7 +230,6 @@ static void test_ssch(void)
 	phys_addr_t base, top;
 
 	assert(css_enable(test_device_sid, IO_SCH_ISC) == 0);
-	assert(register_io_int_func(css_irq_io) == 0);
 
 	/* ORB address should be aligned on 32 bits */
 	report_prefix_push("ORB alignment");
@@ -441,6 +609,8 @@ static struct {
 	{ "enumerate (stsch)", test_enumerate },
 	{ "enable (msch)", test_enable },
 	{ "start subchannel", test_ssch },
+	{ "halt subchannel", test_hsch },
+	{ "clear subchannel", test_csch },
 	{ "sense (ssch/tsch)", test_sense },
 	{ "measurement block (schm)", test_schm },
 	{ "measurement block format0", test_schm_fmt0 },
