s390/qdio: track time of last data IRQ for each device

We currently track the time of the most recent QDIO Adapter Interrupt.
This is a system-wide timestamp (as such interrupts are not bound to
one specific qdio device).

If interrupt processing stalls on one device but is functional for a
different device, the timestamp continues to be updated and is of no
help for problem diagnosis.
So for debugging purposes also track the time of the last Data IRQ on
a per-device level. Collect this data in the legacy non-AI path as well.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

drivers/s390/cio/qdio.h

@@ -252,6 +252,7 @@ struct qdio_irq {
 	struct ccw_device *cdev;
 	struct list_head entry;		/* list of thinint devices */
 	struct dentry *debugfs_dev;
+	u64 last_data_irq_time;
 
 	unsigned long int_parm;
 	struct subchannel_id schid;

drivers/s390/cio/qdio_debug.c

@@ -105,8 +105,9 @@ static int qstat_show(struct seq_file *m, void *v)
 	if (!q)
 		return 0;
 
-	seq_printf(m, "Timestamp: %Lx  Last AI: %Lx\n",
-		   q->timestamp, last_ai_time);
+	seq_printf(m, "Timestamp: %llx\n", q->timestamp);
+	seq_printf(m, "Last Data IRQ: %llx  Last AI: %llx\n",
+		   q->irq_ptr->last_data_irq_time, last_ai_time);
 	seq_printf(m, "nr_used: %d  ftc: %d\n",
 		   atomic_read(&q->nr_buf_used), q->first_to_check);
 	if (q->is_input_q) {

drivers/s390/cio/qdio_main.c

@@ -804,6 +804,7 @@ static void qdio_int_handler_pci(struct qdio_irq *irq_ptr)
 		return;
 
 	qdio_deliver_irq(irq_ptr);
+	irq_ptr->last_data_irq_time = S390_lowcore.int_clock;
 
 	if (!pci_out_supported(irq_ptr) || !irq_ptr->scan_threshold)
 		return;

drivers/s390/cio/qdio_thinint.c

@@ -97,10 +97,11 @@ static inline u32 clear_shared_ind(void)
  */
 static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
 {
+	u64 irq_time = S390_lowcore.int_clock;
 	u32 si_used = clear_shared_ind();
 	struct qdio_irq *irq;
 
-	last_ai_time = S390_lowcore.int_clock;
+	last_ai_time = irq_time;
 	inc_irq_stat(IRQIO_QAI);
 
 	/* protect tiq_list entries, only changed in activate or shutdown */
@@ -119,6 +120,7 @@ static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
 		}
 
 		qdio_deliver_irq(irq);
+		irq->last_data_irq_time = irq_time;
 
 		QDIO_PERF_STAT_INC(irq, adapter_int);
 	}