scsi: ufs: Support clearing multiple commands at once

Modify ufshcd_clear_cmd() such that it supports clearing multiple commands
at once instead of one command at a time. This change will be used in a
later patch to reduce the time spent in the reset handler.

Link: https://lore.kernel.org/r/20220613214442.212466-3-bvanassche@acm.org
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: bvanassche

drivers/ufs/core/ufshcd.c

@@ -748,17 +748,28 @@ static enum utp_ocs ufshcd_get_tr_ocs(struct ufshcd_lrb *lrbp)
 }
 
 /**
- * ufshcd_utrl_clear - Clear a bit in UTRLCLR register
+ * ufshcd_utrl_clear() - Clear requests from the controller request list.
  * @hba: per adapter instance
- * @pos: position of the bit to be cleared
+ * @mask: mask with one bit set for each request to be cleared
  */
-static inline void ufshcd_utrl_clear(struct ufs_hba *hba, u32 pos)
+static inline void ufshcd_utrl_clear(struct ufs_hba *hba, u32 mask)
 {
 	if (hba->quirks & UFSHCI_QUIRK_BROKEN_REQ_LIST_CLR)
-		ufshcd_writel(hba, (1 << pos), REG_UTP_TRANSFER_REQ_LIST_CLEAR);
-	else
-		ufshcd_writel(hba, ~(1 << pos),
-				REG_UTP_TRANSFER_REQ_LIST_CLEAR);
+		mask = ~mask;
+	/*
+	 * From the UFSHCI specification: "UTP Transfer Request List CLear
+	 * Register (UTRLCLR): This field is bit significant. Each bit
+	 * corresponds to a slot in the UTP Transfer Request List, where bit 0
+	 * corresponds to request slot 0. A bit in this field is set to ‘0’
+	 * by host software to indicate to the host controller that a transfer
+	 * request slot is cleared. The host controller
+	 * shall free up any resources associated to the request slot
+	 * immediately, and shall set the associated bit in UTRLDBR to ‘0’. The
+	 * host software indicates no change to request slots by setting the
+	 * associated bits in this field to ‘1’. Bits in this field shall only
+	 * be set ‘1’ or ‘0’ by host software when UTRLRSR is set to ‘1’."
+	 */
+	ufshcd_writel(hba, ~mask, REG_UTP_TRANSFER_REQ_LIST_CLEAR);
 }
 
 /**
@@ -2863,15 +2874,18 @@ static int ufshcd_compose_dev_cmd(struct ufs_hba *hba,
 	return ufshcd_compose_devman_upiu(hba, lrbp);
 }
 
-static int
-ufshcd_clear_cmd(struct ufs_hba *hba, int tag)
+/*
+ * Clear all the requests from the controller for which a bit has been set in
+ * @mask and wait until the controller confirms that these requests have been
+ * cleared.
+ */
+static int ufshcd_clear_cmds(struct ufs_hba *hba, u32 mask)
 {
 	unsigned long flags;
-	u32 mask = 1 << tag;
 
 	/* clear outstanding transaction before retry */
 	spin_lock_irqsave(hba->host->host_lock, flags);
-	ufshcd_utrl_clear(hba, tag);
+	ufshcd_utrl_clear(hba, mask);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
 	/*
@@ -2959,7 +2973,7 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
 		err = -ETIMEDOUT;
 		dev_dbg(hba->dev, "%s: dev_cmd request timedout, tag %d\n",
 			__func__, lrbp->task_tag);
-		if (!ufshcd_clear_cmd(hba, lrbp->task_tag))
+		if (!ufshcd_clear_cmds(hba, 1U << lrbp->task_tag))
 			/* successfully cleared the command, retry if needed */
 			err = -EAGAIN;
 		/*
@@ -6982,7 +6996,7 @@ static int ufshcd_eh_device_reset_handler(struct scsi_cmnd *cmd)
 	/* clear the commands that were pending for corresponding LUN */
 	for_each_set_bit(pos, &hba->outstanding_reqs, hba->nutrs) {
 		if (hba->lrb[pos].lun == lun) {
-			err = ufshcd_clear_cmd(hba, pos);
+			err = ufshcd_clear_cmds(hba, 1U << pos);
 			if (err)
 				break;
 			__ufshcd_transfer_req_compl(hba, 1U << pos);
@@ -7084,7 +7098,7 @@ static int ufshcd_try_to_abort_task(struct ufs_hba *hba, int tag)
 		goto out;
 	}
 
-	err = ufshcd_clear_cmd(hba, tag);
+	err = ufshcd_clear_cmds(hba, 1U << tag);
 	if (err)
 		dev_err(hba->dev, "%s: Failed clearing cmd at tag %d, err %d\n",
 			__func__, tag, err);