scsi: cxlflash: Support SQ Command Mode

The SISLite specification outlines a new queuing model to improve
over the MMIO-based IOARRIN model that exists today. This new model
uses a submission queue that exists in host memory and is shared with
the device. Each entry in the queue is an IOARCB that describes a
transfer request. When requests are submitted, IOARCBs ('current'
position tracked in host software) are populated and the submission
queue tail pointer is then updated via MMIO to make the device aware
of the requests.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/cxlflash/common.h

@@ -54,6 +54,9 @@ extern const struct file_operations cxlflash_cxl_fops;
 /* RRQ for master issued cmds */
 #define NUM_RRQ_ENTRY                   CXLFLASH_MAX_CMDS
 
+/* SQ for master issued cmds */
+#define NUM_SQ_ENTRY			CXLFLASH_MAX_CMDS
+
 
 static inline void check_sizes(void)
 {
@@ -155,8 +158,8 @@ static inline struct afu_cmd *sc_to_afucz(struct scsi_cmnd *sc)
 
 struct afu {
 	/* Stuff requiring alignment go first. */
-
-	u64 rrq_entry[NUM_RRQ_ENTRY];	/* 2K RRQ */
+	struct sisl_ioarcb sq[NUM_SQ_ENTRY];		/* 16K SQ */
+	u64 rrq_entry[NUM_RRQ_ENTRY];			/* 2K RRQ */
 
 	/* Beware of alignment till here. Preferably introduce new
 	 * fields after this point
@@ -174,6 +177,12 @@ struct afu {
 	struct kref mapcount;
 
 	ctx_hndl_t ctx_hndl;	/* master's context handle */
+
+	atomic_t hsq_credits;
+	spinlock_t hsq_slock;
+	struct sisl_ioarcb *hsq_start;
+	struct sisl_ioarcb *hsq_end;
+	struct sisl_ioarcb *hsq_curr;
 	u64 *hrrq_start;
 	u64 *hrrq_end;
 	u64 *hrrq_curr;
@@ -191,6 +200,23 @@ struct afu {
 
 };
 
+static inline bool afu_is_cmd_mode(struct afu *afu, u64 cmd_mode)
+{
+	u64 afu_cap = afu->interface_version >> SISL_INTVER_CAP_SHIFT;
+
+	return afu_cap & cmd_mode;
+}
+
+static inline bool afu_is_sq_cmd_mode(struct afu *afu)
+{
+	return afu_is_cmd_mode(afu, SISL_INTVER_CAP_SQ_CMD_MODE);
+}
+
+static inline bool afu_is_ioarrin_cmd_mode(struct afu *afu)
+{
+	return afu_is_cmd_mode(afu, SISL_INTVER_CAP_IOARRIN_CMD_MODE);
+}
+
 static inline u64 lun_to_lunid(u64 lun)
 {
 	__be64 lun_id;