Merge tag 'isci-for-3.5' into misc

isci update for 3.5

1/ Rework remote-node-context (RNC) handling for proper management of
   the silicon state machine in error handling and hot-plug conditions.
   Further details below, suffice to say if the RNC is mismanaged the
   silicon state machines may lock up.

2/ Refactor the initialization code to be reused for suspend/resume support

3/ Miscellaneous bug fixes to address discovery issues and hardware
   compatibility.

RNC rework details from Jeff Skirvin:

In the controller, devices as they appear on a SAS domain (or
direct-attached SATA devices) are represented by memory structures known
as "Remote Node Contexts" (RNCs).  These structures are transferred from
main memory to the controller using a set of register commands; these
commands include setting up the context ("posting"), removing the
context ("invalidating"), and commands to control the scheduling of
commands and connections to that remote device ("suspensions" and
"resumptions").  There is a similar path to control RNC scheduling from
the protocol engine, which interprets the results of command and data
transmission and reception.

In general, the controller chooses among non-suspended RNCs to find one
that has work requiring scheduling the transmission of command and data
frames to a target.  Likewise, when a target tries to return data back
to the initiator, the state of the RNC is used by the controller to
determine how to treat the incoming request. As an example, if the RNC
is in the state "TX/RX Suspended", incoming SSP connection requests from
the target will be rejected by the controller hardware.  When an RNC is
"TX Suspended", it will not be selected by the controller hardware to
start outgoing command or data operations (with certain priority-based
exceptions).

As mentioned above, there are two sources for management of the RNC
states: commands from driver software, and the result of transmission
and reception conditions of commands and data signaled by the controller
hardware.  As an example of the latter, if an outgoing SSP command ends
with a OPEN_REJECT(BAD_DESTINATION) status, the RNC state will
transition to the "TX Suspended" state, and this is signaled by the
controller hardware in the status to the completion of the pending
command as well as signaled in a controller hardware event.  Examples of
the former are included in the patch changelogs.

Driver software is required to suspend the RNC in a "TX/RX Suspended"
condition before any outstanding commands can be terminated.  Failure to
guarantee this can lead to a complete hardware hang condition.  Earlier
versions of the driver software did not guarantee that an RNC was
correctly managed before I/O termination, and so operated in an unsafe
way.

Further, the driver performed unnecessary contortions to preserve the
remote device command state and so was more complicated than it needed
to be.  A simplifying driver assumption is that once an I/O has entered
the error handler path without having completed in the target, the
requirement on the driver is that all use of the sas_task must end.
Beyond that, recovery of operation is dependent on libsas and other
components to reset, rediscover and reconfigure the device before normal
operation can restart.  In the driver, this simplifying assumption meant
that the RNC management could be reduced to entry into the suspended
state, terminating the targeted I/O request, and resuming the RNC as
needed for device-specific management such as an SSP Abort Task or LUN
Reset Management request.

1 files changed, 33 insertions, 10 deletions

diff --git a/drivers/scsi/isci/remote_node_context.h b/drivers/scsi/isci/remote_node_context.h
index a241e0f4c865..a703b9ce0c2c 100644
--- a/drivers/scsi/isci/remote_node_context.h
+++ b/drivers/scsi/isci/remote_node_context.h
@@ -75,8 +75,13 @@
  */
 #define SCIC_SDS_REMOTE_NODE_CONTEXT_INVALID_INDEX    0x0FFF
 
-#define SCU_HARDWARE_SUSPENSION  (0)
-#define SCI_SOFTWARE_SUSPENSION  (1)
+enum sci_remote_node_suspension_reasons {
+	SCI_HW_SUSPEND,
+	SCI_SW_SUSPEND_NORMAL,
+	SCI_SW_SUSPEND_LINKHANG_DETECT
+};
+#define SCI_SOFTWARE_SUSPEND_CMD SCU_CONTEXT_COMMAND_POST_RNC_SUSPEND_TX_RX
+#define SCI_SOFTWARE_SUSPEND_EXPECTED_EVENT SCU_EVENT_TL_RNC_SUSPEND_TX_RX
 
 struct isci_request;
 struct isci_remote_device;
@@ -137,9 +142,13 @@ const char *rnc_state_name(enum scis_sds_remote_node_context_states state);
  * node context.
  */
 enum sci_remote_node_context_destination_state {
-	SCIC_SDS_REMOTE_NODE_DESTINATION_STATE_UNSPECIFIED,
-	SCIC_SDS_REMOTE_NODE_DESTINATION_STATE_READY,
-	SCIC_SDS_REMOTE_NODE_DESTINATION_STATE_FINAL
+	RNC_DEST_UNSPECIFIED,
+	RNC_DEST_READY,
+	RNC_DEST_FINAL,
+	RNC_DEST_SUSPENDED,       /* Set when suspend during post/invalidate */
+	RNC_DEST_SUSPENDED_RESUME /* Set when a resume was done during posting
+				   * or invalidating and already suspending.
+				   */
 };
 
 /**
@@ -156,10 +165,12 @@ struct sci_remote_node_context {
 	u16 remote_node_index;
 
 	/**
-	 * This field is the recored suspension code or the reason for the remote node
+	 * This field is the recored suspension type of the remote node
 	 * context suspension.
 	 */
-	u32 suspension_code;
+	u32 suspend_type;
+	enum sci_remote_node_suspension_reasons suspend_reason;
+	u32 suspend_count;
 
 	/**
 	 * This field is true if the remote node context is resuming from its current
@@ -193,6 +204,8 @@ void sci_remote_node_context_construct(struct sci_remote_node_context *rnc,
 bool sci_remote_node_context_is_ready(
 	struct sci_remote_node_context *sci_rnc);
 
+bool sci_remote_node_context_is_suspended(struct sci_remote_node_context *sci_rnc);
+
 enum sci_status sci_remote_node_context_event_handler(struct sci_remote_node_context *sci_rnc,
 							   u32 event_code);
 enum sci_status sci_remote_node_context_destruct(struct sci_remote_node_context *sci_rnc,
@@ -200,14 +213,24 @@ enum sci_status sci_remote_node_context_destruct(struct sci_remote_node_context
 						      void *callback_parameter);
 enum sci_status sci_remote_node_context_suspend(struct sci_remote_node_context *sci_rnc,
 						     u32 suspend_type,
-						     scics_sds_remote_node_context_callback cb_fn,
-						     void *cb_p);
+						     u32 suspension_code);
 enum sci_status sci_remote_node_context_resume(struct sci_remote_node_context *sci_rnc,
 						    scics_sds_remote_node_context_callback cb_fn,
 						    void *cb_p);
 enum sci_status sci_remote_node_context_start_task(struct sci_remote_node_context *sci_rnc,
-							struct isci_request *ireq);
+						   struct isci_request *ireq,
+						   scics_sds_remote_node_context_callback cb_fn,
+						   void *cb_p);
 enum sci_status sci_remote_node_context_start_io(struct sci_remote_node_context *sci_rnc,
 						      struct isci_request *ireq);
+int sci_remote_node_context_is_safe_to_abort(
+	struct sci_remote_node_context *sci_rnc);
 
+static inline bool sci_remote_node_context_is_being_destroyed(
+	struct sci_remote_node_context *sci_rnc)
+{
+	return (sci_rnc->destination_state == RNC_DEST_FINAL)
+		|| ((sci_rnc->sm.current_state_id == SCI_RNC_INITIAL)
+		    && (sci_rnc->destination_state == RNC_DEST_UNSPECIFIED));
+}
 #endif  /* _SCIC_SDS_REMOTE_NODE_CONTEXT_H_ */