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;
+}