scsi: ufs: mcq: Make .get_hba_mac() optional

UFSHCI controllers that are compliant with the UFSHCI 4.0 standard report
the maximum number of supported commands in the controller capabilities
register. Use that value if .get_hba_mac == NULL.

Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240708211716.2827751-11-bvanassche@acm.org
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/core/ufs-mcq.c

@@ -138,18 +138,26 @@ EXPORT_SYMBOL_GPL(ufshcd_mcq_queue_cfg_addr);
  *
  * MAC - Max. Active Command of the Host Controller (HC)
  * HC wouldn't send more than this commands to the device.
- * It is mandatory to implement get_hba_mac() to enable MCQ mode.
  * Calculates and adjusts the queue depth based on the depth
  * supported by the HC and ufs device.
  */
 int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba)
 {
-	int mac = -EOPNOTSUPP;
+	int mac;
 
-	if (!hba->vops || !hba->vops->get_hba_mac)
-		goto err;
-
-	mac = hba->vops->get_hba_mac(hba);
+	if (!hba->vops || !hba->vops->get_hba_mac) {
+		/*
+		 * Extract the maximum number of active transfer tasks value
+		 * from the host controller capabilities register. This value is
+		 * 0-based.
+		 */
+		hba->capabilities =
+			ufshcd_readl(hba, REG_CONTROLLER_CAPABILITIES);
+		mac = hba->capabilities & MASK_TRANSFER_REQUESTS_SLOTS_MCQ;
+		mac++;
+	} else {
+		mac = hba->vops->get_hba_mac(hba);
+	}
 	if (mac < 0)
 		goto err;
 
@@ -424,6 +432,12 @@ void ufshcd_mcq_enable(struct ufs_hba *hba)
 }
 EXPORT_SYMBOL_GPL(ufshcd_mcq_enable);
 
+void ufshcd_mcq_disable(struct ufs_hba *hba)
+{
+	ufshcd_rmwl(hba, MCQ_MODE_SELECT, 0, REG_UFS_MEM_CFG);
+	hba->mcq_enabled = false;
+}
+
 void ufshcd_mcq_config_esi(struct ufs_hba *hba, struct msi_msg *msg)
 {
 	ufshcd_writel(hba, msg->address_lo, REG_UFS_ESILBA);

drivers/ufs/core/ufshcd-priv.h

@@ -64,6 +64,7 @@ void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
 void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
 			  struct cq_entry *cqe);
 int ufshcd_mcq_init(struct ufs_hba *hba);
+void ufshcd_mcq_disable(struct ufs_hba *hba);
 int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba);
 int ufshcd_mcq_memory_alloc(struct ufs_hba *hba);
 struct ufs_hw_queue *ufshcd_mcq_req_to_hwq(struct ufs_hba *hba,

drivers/ufs/core/ufshcd.c

@@ -8753,12 +8753,13 @@ static int ufshcd_device_init(struct ufs_hba *hba, bool init_dev_params)
 		if (ret)
 			return ret;
 		if (is_mcq_supported(hba) && !hba->scsi_host_added) {
+			ufshcd_mcq_enable(hba);
 			ret = ufshcd_alloc_mcq(hba);
 			if (!ret) {
 				ufshcd_config_mcq(hba);
-				ufshcd_mcq_enable(hba);
 			} else {
 				/* Continue with SDB mode */
+				ufshcd_mcq_disable(hba);
 				use_mcq_mode = false;
 				dev_err(hba->dev, "MCQ mode is disabled, err=%d\n",
 					 ret);

include/ufs/ufshcd.h

@@ -325,7 +325,9 @@ struct ufs_pwr_mode_info {
  * @event_notify: called to notify important events
  * @reinit_notify: called to notify reinit of UFSHCD during max gear switch
  * @mcq_config_resource: called to configure MCQ platform resources
- * @get_hba_mac: called to get vendor specific mac value, mandatory for mcq mode
+ * @get_hba_mac: reports maximum number of outstanding commands supported by
+ *	the controller. Should be implemented for UFSHCI 4.0 or later
+ *	controllers that are not compliant with the UFSHCI 4.0 specification.
  * @op_runtime_config: called to config Operation and runtime regs Pointers
  * @get_outstanding_cqs: called to get outstanding completion queues
  * @config_esi: called to config Event Specific Interrupt

include/ufs/ufshci.h

@@ -68,6 +68,7 @@ enum {
 /* Controller capability masks */
 enum {
 	MASK_TRANSFER_REQUESTS_SLOTS_SDB	= 0x0000001F,
+	MASK_TRANSFER_REQUESTS_SLOTS_MCQ	= 0x000000FF,
 	MASK_NUMBER_OUTSTANDING_RTT		= 0x0000FF00,
 	MASK_TASK_MANAGEMENT_REQUEST_SLOTS	= 0x00070000,
 	MASK_EHSLUTRD_SUPPORTED			= 0x00400000,