isci: cleanup/optimize queue increment macros

Every single i/o or event completion incurs a test and branch to see if
the cycle bit changed.  For power-of-2 queue sizes the cycle bit can be
read directly from the rollover of the queue pointer.

Likely premature optimization, but the hidden if() and hidden
assignments / side-effects in the macros were already asking to be
cleaned up.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

4 files changed, 44 insertions, 90 deletions

diff --git a/drivers/scsi/isci/host.c b/drivers/scsi/isci/host.c
index 3c7042b8bc0e..ae9edae1d245 100644
--- a/drivers/scsi/isci/host.c
+++ b/drivers/scsi/isci/host.c
@@ -123,34 +123,6 @@
 	)
 
 /**
- * INCREMENT_COMPLETION_QUEUE_GET() -
- *
- * This macro will increment the controllers completion queue index value and
- * possibly toggle the cycle bit if the completion queue index wraps back to 0.
- */
-#define INCREMENT_COMPLETION_QUEUE_GET(controller, index, cycle) \
-	INCREMENT_QUEUE_GET(\
-		(index), \
-		(cycle), \
-		SCU_MAX_COMPLETION_QUEUE_ENTRIES, \
-		SMU_CQGR_CYCLE_BIT)
-
-/**
- * INCREMENT_EVENT_QUEUE_GET() -
- *
- * This macro will increment the controllers event queue index value and
- * possibly toggle the event cycle bit if the event queue index wraps back to 0.
- */
-#define INCREMENT_EVENT_QUEUE_GET(controller, index, cycle) \
-	INCREMENT_QUEUE_GET(\
-		(index), \
-		(cycle), \
-		SCU_MAX_EVENTS, \
-		SMU_CQGR_EVENT_CYCLE_BIT \
-		)
-
-
-/**
  * NORMALIZE_GET_POINTER() -
  *
  * This macro will normalize the completion queue get pointer so its value can
@@ -528,15 +500,13 @@ static void scic_sds_controller_event_completion(struct scic_sds_controller *sci
 	}
 }
 
-
-
 static void scic_sds_controller_process_completions(struct scic_sds_controller *scic)
 {
 	u32 completion_count = 0;
 	u32 completion_entry;
 	u32 get_index;
 	u32 get_cycle;
-	u32 event_index;
+	u32 event_get;
 	u32 event_cycle;
 
 	dev_dbg(scic_to_dev(scic),
@@ -548,7 +518,7 @@ static void scic_sds_controller_process_completions(struct scic_sds_controller *
 	get_index = NORMALIZE_GET_POINTER(scic->completion_queue_get);
 	get_cycle = SMU_CQGR_CYCLE_BIT & scic->completion_queue_get;
 
-	event_index = NORMALIZE_EVENT_POINTER(scic->completion_queue_get);
+	event_get = NORMALIZE_EVENT_POINTER(scic->completion_queue_get);
 	event_cycle = SMU_CQGR_EVENT_CYCLE_BIT & scic->completion_queue_get;
 
 	while (
@@ -558,7 +528,11 @@ static void scic_sds_controller_process_completions(struct scic_sds_controller *
 		completion_count++;
 
 		completion_entry = scic->completion_queue[get_index];
-		INCREMENT_COMPLETION_QUEUE_GET(scic, get_index, get_cycle);
+
+		/* increment the get pointer and check for rollover to toggle the cycle bit */
+		get_cycle ^= ((get_index+1) & SCU_MAX_COMPLETION_QUEUE_ENTRIES) <<
+			     (SMU_COMPLETION_QUEUE_GET_CYCLE_BIT_SHIFT - SCU_MAX_COMPLETION_QUEUE_SHIFT);
+		get_index = (get_index+1) & (SCU_MAX_COMPLETION_QUEUE_ENTRIES-1);
 
 		dev_dbg(scic_to_dev(scic),
 			"%s: completion queue entry:0x%08x\n",
@@ -579,18 +553,14 @@ static void scic_sds_controller_process_completions(struct scic_sds_controller *
 			break;
 
 		case SCU_COMPLETION_TYPE_EVENT:
-			INCREMENT_EVENT_QUEUE_GET(scic, event_index, event_cycle);
-			scic_sds_controller_event_completion(scic, completion_entry);
-			break;
+		case SCU_COMPLETION_TYPE_NOTIFY: {
+			event_cycle ^= ((event_get+1) & SCU_MAX_EVENTS) <<
+				       (SMU_COMPLETION_QUEUE_GET_EVENT_CYCLE_BIT_SHIFT - SCU_MAX_EVENTS_SHIFT);
+			event_get = (event_get+1) & (SCU_MAX_EVENTS-1);
 
-		case SCU_COMPLETION_TYPE_NOTIFY:
-			/*
-			 * Presently we do the same thing with a notify event that we do with the
-			 * other event codes. */
-			INCREMENT_EVENT_QUEUE_GET(scic, event_index, event_cycle);
 			scic_sds_controller_event_completion(scic, completion_entry);
 			break;
-
+		}
 		default:
 			dev_warn(scic_to_dev(scic),
 				 "%s: SCIC Controller received unknown "
@@ -607,7 +577,7 @@ static void scic_sds_controller_process_completions(struct scic_sds_controller *
 			SMU_CQGR_GEN_BIT(ENABLE) |
 			SMU_CQGR_GEN_BIT(EVENT_ENABLE) |
 			event_cycle |
-			SMU_CQGR_GEN_VAL(EVENT_POINTER, event_index) |
+			SMU_CQGR_GEN_VAL(EVENT_POINTER, event_get) |
 			get_cycle |
 			SMU_CQGR_GEN_VAL(POINTER, get_index);
 
diff --git a/drivers/scsi/isci/host.h b/drivers/scsi/isci/host.h
index 7d17ab80f1a9..94fd54dc9f01 100644
--- a/drivers/scsi/isci/host.h
+++ b/drivers/scsi/isci/host.h
@@ -524,22 +524,6 @@ static inline struct isci_host *scic_to_ihost(struct scic_sds_controller *scic)
 }
 
 /**
- * INCREMENT_QUEUE_GET() -
- *
- * This macro will increment the specified index to and if the index wraps to 0
- * it will toggel the cycle bit.
- */
-#define INCREMENT_QUEUE_GET(index, cycle, entry_count, bit_toggle) \
-	{ \
-		if ((index) + 1 == entry_count) {	\
-			(index) = 0; \
-			(cycle) = (cycle) ^ (bit_toggle); \
-		} else { \
-			index = index + 1; \
-		} \
-	}
-
-/**
  * scic_sds_controller_get_protocol_engine_group() -
  *
  * This macro returns the protocol engine group for this controller object.
diff --git a/drivers/scsi/isci/isci.h b/drivers/scsi/isci/isci.h
index 81bade421b96..207328369edd 100644
--- a/drivers/scsi/isci/isci.h
+++ b/drivers/scsi/isci/isci.h
@@ -90,7 +90,8 @@ enum sci_controller_mode {
 #define SCI_MAX_DOMAINS  SCI_MAX_PORTS
 
 #define SCU_MAX_CRITICAL_NOTIFICATIONS    (384)
-#define SCU_MAX_EVENTS                    (128)
+#define SCU_MAX_EVENTS_SHIFT		  (7)
+#define SCU_MAX_EVENTS                    (1 << SCU_MAX_EVENTS_SHIFT)
 #define SCU_MAX_UNSOLICITED_FRAMES        (128)
 #define SCU_MAX_COMPLETION_QUEUE_SCRATCH  (128)
 #define SCU_MAX_COMPLETION_QUEUE_ENTRIES  (SCU_MAX_CRITICAL_NOTIFICATIONS \
@@ -98,6 +99,7 @@ enum sci_controller_mode {
 					   + SCU_MAX_UNSOLICITED_FRAMES	\
 					   + SCI_MAX_IO_REQUESTS \
 					   + SCU_MAX_COMPLETION_QUEUE_SCRATCH)
+#define SCU_MAX_COMPLETION_QUEUE_SHIFT	  (ilog2(SCU_MAX_COMPLETION_QUEUE_ENTRIES))
 
 #define SCU_ABSOLUTE_MAX_UNSOLICITED_FRAMES (4096)
 #define SCU_UNSOLICITED_FRAME_BUFFER_SIZE   (1024)
diff --git a/drivers/scsi/isci/unsolicited_frame_control.c b/drivers/scsi/isci/unsolicited_frame_control.c
index d89570700ffd..680582d8cde5 100644
--- a/drivers/scsi/isci/unsolicited_frame_control.c
+++ b/drivers/scsi/isci/unsolicited_frame_control.c
@@ -209,7 +209,8 @@ bool scic_sds_unsolicited_frame_control_release_frame(
 	/*
 	 * In the event there are NULL entries in the UF table, we need to
 	 * advance the get pointer in order to find out if this frame should
-	 * be released (i.e. update the get pointer). */
+	 * be released (i.e. update the get pointer)
+	 */
 	while (lower_32_bits(uf_control->address_table.array[frame_get]) == 0 &&
 	       upper_32_bits(uf_control->address_table.array[frame_get]) == 0 &&
 	       frame_get < SCU_MAX_UNSOLICITED_FRAMES)
@@ -217,40 +218,37 @@ bool scic_sds_unsolicited_frame_control_release_frame(
 
 	/*
 	 * The table has a NULL entry as it's last element.  This is
-	 * illegal. */
+	 * illegal.
+	 */
 	BUG_ON(frame_get >= SCU_MAX_UNSOLICITED_FRAMES);
+	if (frame_index >= SCU_MAX_UNSOLICITED_FRAMES)
+		return false;
 
-	if (frame_index < SCU_MAX_UNSOLICITED_FRAMES) {
-		uf_control->buffers.array[frame_index].state = UNSOLICITED_FRAME_RELEASED;
+	uf_control->buffers.array[frame_index].state = UNSOLICITED_FRAME_RELEASED;
 
+	if (frame_get != frame_index) {
 		/*
-		 * The frame index is equal to the current get pointer so we
-		 * can now free up all of the frame entries that */
-		if (frame_get == frame_index) {
-			while (
-				uf_control->buffers.array[frame_get].state
-				== UNSOLICITED_FRAME_RELEASED
-				) {
-				uf_control->buffers.array[frame_get].state = UNSOLICITED_FRAME_EMPTY;
-
-				INCREMENT_QUEUE_GET(
-					frame_get,
-					frame_cycle,
-					SCU_MAX_UNSOLICITED_FRAMES - 1,
-					SCU_MAX_UNSOLICITED_FRAMES);
-			}
-
-			uf_control->get =
-				(SCU_UFQGP_GEN_BIT(ENABLE_BIT) | frame_cycle | frame_get);
+		 * Frames remain in use until we advance the get pointer
+		 * so there is nothing we can do here
+		 */
+		return false;
+	}
 
-			return true;
-		} else {
-			/*
-			 * Frames remain in use until we advance the get pointer
-			 * so there is nothing we can do here */
-		}
+	/*
+	 * The frame index is equal to the current get pointer so we
+	 * can now free up all of the frame entries that
+	 */
+	while (uf_control->buffers.array[frame_get].state == UNSOLICITED_FRAME_RELEASED) {
+		uf_control->buffers.array[frame_get].state = UNSOLICITED_FRAME_EMPTY;
+
+		if (frame_get+1 == SCU_MAX_UNSOLICITED_FRAMES-1) {
+			frame_cycle ^= SCU_MAX_UNSOLICITED_FRAMES;
+			frame_get = 0;
+		} else
+			frame_get++;
 	}
 
-	return false;
-}
+	uf_control->get = SCU_UFQGP_GEN_BIT(ENABLE_BIT) | frame_cycle | frame_get;
 
+	return true;
+}