scsi: ufs: core: Introduce multi-circular queue capability

Add support to check for MCQ capability in the UFSHC.  Add a module
parameter to disable MCQ if needed.

Co-developed-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Asutosh Das <quic_asutoshd@quicinc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/core/ufshcd.c

@@ -92,6 +92,28 @@
 /* Polling time to wait for fDeviceInit */
 #define FDEVICEINIT_COMPL_TIMEOUT 1500 /* millisecs */
 
+/* UFSHC 4.0 compliant HC support this mode, refer param_set_mcq_mode() */
+static bool use_mcq_mode = true;
+
+static int param_set_mcq_mode(const char *val, const struct kernel_param *kp)
+{
+	int ret;
+
+	ret = param_set_bool(val, kp);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct kernel_param_ops mcq_mode_ops = {
+	.set = param_set_mcq_mode,
+	.get = param_get_bool,
+};
+
+module_param_cb(use_mcq_mode, &mcq_mode_ops, &use_mcq_mode, 0644);
+MODULE_PARM_DESC(use_mcq_mode, "Control MCQ mode for controllers starting from UFSHCI 4.0. 1 - enable MCQ, 0 - disable MCQ. MCQ is enabled by default");
+
 #define ufshcd_toggle_vreg(_dev, _vreg, _on)				\
 	({                                                              \
 		int _ret;                                               \
@@ -2261,6 +2283,10 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
 	if (err)
 		dev_err(hba->dev, "crypto setup failed\n");
 
+	hba->mcq_sup = FIELD_GET(MASK_MCQ_SUPPORT, hba->capabilities);
+	if (!hba->mcq_sup)
+		return err;
+
 	hba->mcq_capabilities = ufshcd_readl(hba, REG_MCQCAP);
 	hba->ext_iid_sup = FIELD_GET(MASK_EXT_IID_SUPPORT,
 				     hba->mcq_capabilities);

include/ufs/ufshcd.h

@@ -843,6 +843,7 @@ struct ufs_hba_monitor {
  * @complete_put: whether or not to call ufshcd_rpm_put() from inside
  *	ufshcd_resume_complete()
  * @ext_iid_sup: is EXT_IID is supported by UFSHC
+ * @mcq_sup: is mcq supported by UFSHC
  */
 struct ufs_hba {
 	void __iomem *mmio_base;
@@ -995,6 +996,7 @@ struct ufs_hba {
 	u32 luns_avail;
 	bool complete_put;
 	bool ext_iid_sup;
+	bool mcq_sup;
 };
 
 #ifdef CONFIG_SCSI_UFS_VARIABLE_SG_ENTRY_SIZE