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, 29 insertions, 0 deletions

diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h
index f0037eefd44..0f4ef8769a3 100644
--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -208,6 +208,7 @@ struct qdio_dev_perf_stat {
 	unsigned int eqbs_partial;
 	unsigned int sqbs;
 	unsigned int sqbs_partial;
+	unsigned int int_discarded;
 } ____cacheline_aligned;
 
 struct qdio_queue_perf_stat {
@@ -222,6 +223,10 @@ struct qdio_queue_perf_stat {
 	unsigned int nr_sbal_total;
 };
 
+enum qdio_queue_irq_states {
+	QDIO_QUEUE_IRQS_DISABLED,
+};
+
 struct qdio_input_q {
 	/* input buffer acknowledgement flag */
 	int polling;
@@ -231,6 +236,10 @@ struct qdio_input_q {
 	int ack_count;
 	/* last time of noticing incoming data */
 	u64 timestamp;
+	/* upper-layer polling flag */
+	unsigned long queue_irq_state;
+	/* callback to start upper-layer polling */
+	void (*queue_start_poll) (struct ccw_device *, int, unsigned long);
 };
 
 struct qdio_output_q {
@@ -399,6 +408,26 @@ static inline int multicast_outbound(struct qdio_q *q)
 #define sub_buf(bufnr, dec) \
 	((bufnr - dec) & QDIO_MAX_BUFFERS_MASK)
 
+#define queue_irqs_enabled(q)			\
+	(test_bit(QDIO_QUEUE_IRQS_DISABLED, &q->u.in.queue_irq_state) == 0)
+#define queue_irqs_disabled(q)			\
+	(test_bit(QDIO_QUEUE_IRQS_DISABLED, &q->u.in.queue_irq_state) != 0)
+
+#define TIQDIO_SHARED_IND		63
+
+/* 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 */
+};
+
+extern struct indicator_t *q_indicators;
+
+static inline int shared_ind(struct qdio_irq *irq_ptr)
+{
+	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
+}
+
 /* prototypes for thin interrupt */
 void qdio_setup_thinint(struct qdio_irq *irq_ptr);
 int qdio_establish_thinint(struct qdio_irq *irq_ptr);