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>

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 2d479e3..8789147 100644 (file)
--- a/drivers/ufs/core/ufshcd.c
+++ b/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);