scsi: mpt3sas: Add Atomic RequestDescriptor support on Aero

If the Aero HBA supports Atomic Request Descriptors, it sets the Atomic
Request Descriptor Capable bit in the IOCCapabilities field of the IOCFacts
Reply message. Driver uses an Atomic Request Descriptor as an alternative
method for posting an entry onto a request queue.

The posting of an Atomic Request Descriptor is an atomic operation,
providing a safe mechanism for multiple processors on the host to post
requests without synchronization. This Atomic Request Descriptor format is
identical to first 32 bits of Default Request Descriptor and uses only 32
bits.
Signed-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_base.c

@@ -3653,6 +3653,95 @@ _base_put_smid_default(struct MPT3SAS_ADAPTER *ioc, u16 smid)
 				&ioc->scsi_lookup_lock);
 }
 
+/**
+ * _base_put_smid_scsi_io_atomic - send SCSI_IO request to firmware using
+ *   Atomic Request Descriptor
+ * @ioc: per adapter object
+ * @smid: system request message index
+ * @handle: device handle, unused in this function, for function type match
+ *
+ * Return nothing.
+ */
+static void
+_base_put_smid_scsi_io_atomic(struct MPT3SAS_ADAPTER *ioc, u16 smid,
+	u16 handle)
+{
+	Mpi26AtomicRequestDescriptor_t descriptor;
+	u32 *request = (u32 *)&descriptor;
+
+	descriptor.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_SCSI_IO;
+	descriptor.MSIxIndex = _base_get_msix_index(ioc);
+	descriptor.SMID = cpu_to_le16(smid);
+
+	writel(cpu_to_le32(*request), &ioc->chip->AtomicRequestDescriptorPost);
+}
+
+/**
+ * _base_put_smid_fast_path_atomic - send fast path request to firmware
+ * using Atomic Request Descriptor
+ * @ioc: per adapter object
+ * @smid: system request message index
+ * @handle: device handle, unused in this function, for function type match
+ * Return nothing
+ */
+static void
+_base_put_smid_fast_path_atomic(struct MPT3SAS_ADAPTER *ioc, u16 smid,
+	u16 handle)
+{
+	Mpi26AtomicRequestDescriptor_t descriptor;
+	u32 *request = (u32 *)&descriptor;
+
+	descriptor.RequestFlags = MPI25_REQ_DESCRIPT_FLAGS_FAST_PATH_SCSI_IO;
+	descriptor.MSIxIndex = _base_get_msix_index(ioc);
+	descriptor.SMID = cpu_to_le16(smid);
+
+	writel(cpu_to_le32(*request), &ioc->chip->AtomicRequestDescriptorPost);
+}
+
+/**
+ * _base_put_smid_hi_priority_atomic - send Task Management request to
+ * firmware using Atomic Request Descriptor
+ * @ioc: per adapter object
+ * @smid: system request message index
+ * @msix_task: msix_task will be same as msix of IO incase of task abort else 0
+ *
+ * Return nothing.
+ */
+static void
+_base_put_smid_hi_priority_atomic(struct MPT3SAS_ADAPTER *ioc, u16 smid,
+	u16 msix_task)
+{
+	Mpi26AtomicRequestDescriptor_t descriptor;
+	u32 *request = (u32 *)&descriptor;
+
+	descriptor.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_HIGH_PRIORITY;
+	descriptor.MSIxIndex = msix_task;
+	descriptor.SMID = cpu_to_le16(smid);
+
+	writel(cpu_to_le32(*request), &ioc->chip->AtomicRequestDescriptorPost);
+}
+
+/**
+ * _base_put_smid_default - Default, primarily used for config pages
+ * use Atomic Request Descriptor
+ * @ioc: per adapter object
+ * @smid: system request message index
+ *
+ * Return nothing.
+ */
+static void
+_base_put_smid_default_atomic(struct MPT3SAS_ADAPTER *ioc, u16 smid)
+{
+	Mpi26AtomicRequestDescriptor_t descriptor;
+	u32 *request = (u32 *)&descriptor;
+
+	descriptor.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_DEFAULT_TYPE;
+	descriptor.MSIxIndex = _base_get_msix_index(ioc);
+	descriptor.SMID = cpu_to_le16(smid);
+
+	writel(cpu_to_le32(*request), &ioc->chip->AtomicRequestDescriptorPost);
+}
+
 /**
  * _base_display_OEMs_branding - Display branding string
  * @ioc: per adapter object
@@ -5694,6 +5783,9 @@ _base_get_ioc_facts(struct MPT3SAS_ADAPTER *ioc)
 	if ((facts->IOCCapabilities &
 	      MPI2_IOCFACTS_CAPABILITY_RDPQ_ARRAY_CAPABLE) && (!reset_devices))
 		ioc->rdpq_array_capable = 1;
+	if ((facts->IOCCapabilities & MPI26_IOCFACTS_CAPABILITY_ATOMIC_REQ)
+	    && ioc->is_aero_ioc)
+		ioc->atomic_desc_capable = 1;
 	facts->FWVersion.Word = le32_to_cpu(mpi_reply.FWVersion.Word);
 	facts->IOCRequestFrameSize =
 	    le16_to_cpu(mpi_reply.IOCRequestFrameSize);
@@ -6587,15 +6679,23 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
 
 		break;
 	}
-
-	ioc->put_smid_default = &_base_put_smid_default;
-	ioc->put_smid_fast_path = &_base_put_smid_fast_path;
-	ioc->put_smid_hi_priority = &_base_put_smid_hi_priority;
-	if (ioc->is_mcpu_endpoint)
-		ioc->put_smid_scsi_io = &_base_put_smid_mpi_ep_scsi_io;
-	else
-		ioc->put_smid_scsi_io = &_base_put_smid_scsi_io;
-
+	if (ioc->atomic_desc_capable) {
+		ioc->put_smid_default = &_base_put_smid_default_atomic;
+		ioc->put_smid_scsi_io = &_base_put_smid_scsi_io_atomic;
+		ioc->put_smid_fast_path =
+				&_base_put_smid_fast_path_atomic;
+		ioc->put_smid_hi_priority =
+				&_base_put_smid_hi_priority_atomic;
+	} else {
+		ioc->put_smid_default = &_base_put_smid_default;
+		ioc->put_smid_fast_path = &_base_put_smid_fast_path;
+		ioc->put_smid_hi_priority = &_base_put_smid_hi_priority;
+		if (ioc->is_mcpu_endpoint)
+			ioc->put_smid_scsi_io =
+				&_base_put_smid_mpi_ep_scsi_io;
+		else
+			ioc->put_smid_scsi_io = &_base_put_smid_scsi_io;
+	}
 	/*
 	 * These function pointers for other requests that don't
 	 * the require IEEE scatter gather elements.

drivers/scsi/mpt3sas/mpt3sas_base.h

@@ -1147,6 +1147,7 @@ typedef void (*MPT3SAS_FLUSH_RUNNING_CMDS)(struct MPT3SAS_ADAPTER *ioc);
  *	path functions resulting in Null pointer reference followed by kernel
  *	crash. To avoid the above race condition we use mutex syncrhonization
  *	which ensures the syncrhonization between cli/sysfs_show path.
+ * @atomic_desc_capable: Atomic Request Descriptor support.
  */
 struct MPT3SAS_ADAPTER {
 	struct list_head list;
@@ -1412,6 +1413,7 @@ struct MPT3SAS_ADAPTER {
 	u8		hide_drives;
 	spinlock_t	diag_trigger_lock;
 	u8		diag_trigger_active;
+	u8		atomic_desc_capable;
 	BASE_READ_REG	base_readl;
 	struct SL_WH_MASTER_TRIGGER_T diag_trigger_master;
 	struct SL_WH_EVENT_TRIGGERS_T diag_trigger_event;