[PATCH v2 2/9] scsi: ufshpb: Add host control mode support to rsp_upiu

[Avri Altman <avri.altman@wdc.com>]

In device control mode, the device may recommend the host to either
activate or inactivate a region, and the host should follow. Meaning
those are not actually recommendations, but more of instructions.

On the contrary, in host control mode, the recommendation protocol is
slightly changed:
a) The device may only recommend the host to update a subregion of an
   already-active region. And,
b) The device may *not* recommend to inactivate a region.

Furthermore, in host control mode, the host may choose not to follow any
of the device's recommendations. However, in case of a recommendation to
update an active and clean subregion, it is better to follow those
recommendation because otherwise the host has no other way to know that
some internal relocation took place.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 35 +++++++++++++++++++++++++++++++++++
 drivers/scsi/ufs/ufshpb.h |  6 ++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 46f6a7104e7e..61de80a778a7 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -138,6 +138,8 @@ static void ufshpb_set_ppn_dirty(struct ufshpb_lu *hpb, int rgn_idx,
 	else
 		set_bit_len = cnt;
 
+	set_bit(RGN_FLAG_DIRTY, &rgn->rgn_flags);
+
 	if (rgn->rgn_state != HPB_RGN_INACTIVE &&
 	    srgn->srgn_state == HPB_SRGN_VALID)
 		bitmap_set(srgn->mctx->ppn_dirty, srgn_offset, set_bit_len);
@@ -199,6 +201,11 @@ static bool ufshpb_test_ppn_dirty(struct ufshpb_lu *hpb, int rgn_idx,
 	return false;
 }
 
+static inline bool is_rgn_dirty(struct ufshpb_region *rgn)
+{
+	return test_bit(RGN_FLAG_DIRTY, &rgn->rgn_flags);
+}
+
 static u64 ufshpb_get_ppn(struct ufshpb_lu *hpb,
 			  struct ufshpb_map_ctx *mctx, int pos, int *error)
 {
@@ -380,8 +387,12 @@ static void ufshpb_put_map_req(struct ufshpb_lu *hpb,
 static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
 				     struct ufshpb_subregion *srgn)
 {
+	struct ufshpb_region *rgn;
+
 	WARN_ON(!srgn->mctx);
 	bitmap_zero(srgn->mctx->ppn_dirty, hpb->entries_per_srgn);
+	rgn = hpb->rgn_tbl + srgn->rgn_idx;
+	clear_bit(RGN_FLAG_DIRTY, &rgn->rgn_flags);
 	return 0;
 }
 
@@ -814,17 +825,39 @@ static void ufshpb_rsp_req_region_update(struct ufshpb_lu *hpb,
 	 */
 	spin_lock(&hpb->rsp_list_lock);
 	for (i = 0; i < rsp_field->active_rgn_cnt; i++) {
+		struct ufshpb_region *rgn;
+
 		rgn_idx =
 			be16_to_cpu(rsp_field->hpb_active_field[i].active_rgn);
 		srgn_idx =
 			be16_to_cpu(rsp_field->hpb_active_field[i].active_srgn);
 
+		rgn = hpb->rgn_tbl + rgn_idx;
+		if (hpb->is_hcm &&
+		    (rgn->rgn_state != HPB_RGN_ACTIVE || is_rgn_dirty(rgn))) {
+			/*
+			 * in host control mode, subregion activation
+			 * recommendations are only allowed to active regions.
+			 * Also, ignore recommendations for dirty regions - the
+			 * host will make decisions concerning those by himself
+			 */
+			continue;
+		}
+
 		dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
 			"activate(%d) region %d - %d\n", i, rgn_idx, srgn_idx);
 		ufshpb_update_active_info(hpb, rgn_idx, srgn_idx);
 		hpb->stats.rb_active_cnt++;
 	}
 
+	if (hpb->is_hcm) {
+		/*
+		 * in host control mode the device is not allowed to inactivate
+		 * regions
+		 */
+		goto out_unlock;
+	}
+
 	for (i = 0; i < rsp_field->inactive_rgn_cnt; i++) {
 		rgn_idx = be16_to_cpu(rsp_field->hpb_inactive_field[i]);
 		dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
@@ -832,6 +865,8 @@ static void ufshpb_rsp_req_region_update(struct ufshpb_lu *hpb,
 		ufshpb_update_inactive_info(hpb, rgn_idx);
 		hpb->stats.rb_inactive_cnt++;
 	}
+
+out_unlock:
 	spin_unlock(&hpb->rsp_list_lock);
 
 	dev_dbg(&hpb->sdev_ufs_lu->sdev_dev, "Noti: #ACT %u #INACT %u\n",
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index afeb6365daf8..5ec4023db74d 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -48,6 +48,11 @@ enum UFSHPB_MODE {
 	HPB_DEVICE_CONTROL,
 };
 
+enum HPB_RGN_FLAGS {
+	RGN_FLAG_UPDATE = 0,
+	RGN_FLAG_DIRTY,
+};
+
 enum UFSHPB_STATE {
 	HPB_PRESENT = 1,
 	HPB_SUSPEND,
@@ -109,6 +114,7 @@ struct ufshpb_region {
 
 	/* below information is used by lru */
 	struct list_head list_lru_rgn;
+	unsigned long rgn_flags;
 };
 
 #define for_each_sub_region(rgn, i, srgn)				\
-- 
2.25.1