qdio: extend API to allow polling

Extend the qdio API to allow polling in the upper-layer driver. This
is needed by qeth to use NAPI.

To use the new interface the upper-layer driver must specify the
queue_start_poll(). This callback is used to signal the upper-layer
driver that is has initiative and must process the inbound queue by
calling qdio_get_next_buffers(). If the upper-layer driver wants to
stop polling it calls qdio_start_irq().

Since adapter interrupts are not completely stoppable qdio implements
a software bit QDIO_QUEUE_IRQS_DISABLED to safely disable interrupts for an
input queue.

The old interface is preserved and will be used as is by zfcp.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 38 insertions, 28 deletions

diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c
index 8daf1b99f153..752dbee06af5 100644
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -25,24 +25,20 @@
  */
 #define TIQDIO_NR_NONSHARED_IND         63
 #define TIQDIO_NR_INDICATORS            (TIQDIO_NR_NONSHARED_IND + 1)
-#define TIQDIO_SHARED_IND               63
 
 /* list of thin interrupt input queues */
 static LIST_HEAD(tiq_list);
 DEFINE_MUTEX(tiq_list_lock);
 
 /* adapter local summary indicator */
-static unsigned char *tiqdio_alsi;
+static u8 *tiqdio_alsi;
 
-/* device state change indicators */
-struct indicator_t {
-        u32 ind;        /* u32 because of compare-and-swap performance */
-        atomic_t count; /* use count, 0 or 1 for non-shared indicators */
-};
-static struct indicator_t *q_indicators;
+struct indicator_t *q_indicators;
 
 static int css_qdio_omit_svs;
 
+static u64 last_ai_time;
+
 static inline unsigned long do_clear_global_summary(void)
 {
         register unsigned long __fn asm("1") = 3;
@@ -116,59 +112,73 @@ void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
         }
 }
 
-static inline int shared_ind(struct qdio_irq *irq_ptr)
+static inline int shared_ind_used(void)
 {
-        return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
+        return atomic_read(&q_indicators[TIQDIO_SHARED_IND].count);
 }
 
 /**
  * tiqdio_thinint_handler - thin interrupt handler for qdio
- * @ind: pointer to adapter local summary indicator
- * @drv_data: NULL
+ * @alsi: pointer to adapter local summary indicator
+ * @data: NULL
  */
-static void tiqdio_thinint_handler(void *ind, void *drv_data)
+static void tiqdio_thinint_handler(void *alsi, void *data)
 {
         struct qdio_q *q;
 
+        last_ai_time = S390_lowcore.int_clock;
+
         /*
          * SVS only when needed: issue SVS to benefit from iqdio interrupt
-         * avoidance (SVS clears adapter interrupt suppression overwrite)
+         * avoidance (SVS clears adapter interrupt suppression overwrite).
          */
         if (!css_qdio_omit_svs)
                 do_clear_global_summary();
 
-        /*
-         * reset local summary indicator (tiqdio_alsi) to stop adapter
-         * interrupts for now
-         */
-        xchg((u8 *)ind, 0);
+        /* reset local summary indicator */
+        if (shared_ind_used())
+                xchg(tiqdio_alsi, 0);
 
         /* protect tiq_list entries, only changed in activate or shutdown */
         rcu_read_lock();
 
         /* check for work on all inbound thinint queues */
-        list_for_each_entry_rcu(q, &tiq_list, entry)
+        list_for_each_entry_rcu(q, &tiq_list, entry) {
+
                 /* only process queues from changed sets */
-                if (*q->irq_ptr->dsci) {
-                        qperf_inc(q, adapter_int);
+                if (!*q->irq_ptr->dsci)
+                        continue;
 
+                if (q->u.in.queue_start_poll) {
+                        /* skip if polling is enabled or already in work */
+                        if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
+                                             &q->u.in.queue_irq_state)) {
+                                qperf_inc(q, int_discarded);
+                                continue;
+                        }
+
+                        /* avoid dsci clear here, done after processing */
+                        q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,
+                                                 q->irq_ptr->int_parm);
+                } else {
                         /* only clear it if the indicator is non-shared */
                         if (!shared_ind(q->irq_ptr))
                                 xchg(q->irq_ptr->dsci, 0);
                         /*
-                         * don't call inbound processing directly since
-                         * that could starve other thinint queues
+                         * Call inbound processing but not directly
+                         * since that could starve other thinint queues.
                          */
                         tasklet_schedule(&q->tasklet);
                 }
-
+                qperf_inc(q, adapter_int);
+        }
         rcu_read_unlock();
 
         /*
-         * if we used the shared indicator clear it now after all queues
-         * were processed
+         * If the shared indicator was used clear it now after all queues
+         * were processed.
          */
-        if (atomic_read(&q_indicators[TIQDIO_SHARED_IND].count)) {
+        if (shared_ind_used()) {
                 xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
 
                 /* prevent racing */