[RFC PATCH v1 1/7] nvme-core: Read CQT wait from identify controller response

[Mohamed Khalfella <mkhalfella@purestorage.com>]

From: Jyoti Rani <jrani@purestorage.com>

CQT wait tells us how much time in milliseconds nvme controller needs to
quiesce pending nvme commands after learning loss of connectivity. Read
it from identify controller response and store it in struct nvme_ctrl in
cqt field. ctrl->cqt will be used later on to calculate the total time
inflight requests need to be held before they can be safely retried.

Signed-off-by: Jyoti Rani <jrani@purestorage.com>
---
 drivers/nvme/host/core.c | 1 +
 drivers/nvme/host/nvme.h | 1 +
 include/linux/nvme.h     | 4 +++-
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 8359d0aa0e44..f4b3c6a42e90 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3364,6 +3364,7 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->oaes = le32_to_cpu(id->oaes);
 	ctrl->wctemp = le16_to_cpu(id->wctemp);
 	ctrl->cctemp = le16_to_cpu(id->cctemp);
+	ctrl->cqt = le16_to_cpu(id->cqt);
 
 	atomic_set(&ctrl->abort_limit, id->acl + 1);
 	ctrl->vwc = id->vwc;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 7be92d07430e..7563332b5b7b 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -344,6 +344,7 @@ struct nvme_ctrl {
 	u32 oaes;
 	u32 aen_result;
 	u32 ctratt;
+	u16 cqt;
 	unsigned int shutdown_timeout;
 	unsigned int kato;
 	bool subsystem;
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 2dc05b1c3283..7a94c01f0f06 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -361,7 +361,9 @@ struct nvme_id_ctrl {
 	__u8			anacap;
 	__le32			anagrpmax;
 	__le32			nanagrpid;
-	__u8			rsvd352[160];
+	__u8			rsvd352[34];
+	__le16			cqt;
+	__u8			rsvd388[124];
 	__u8			sqes;
 	__u8			cqes;
 	__le16			maxcmd;
-- 
2.48.1