[PATCH v7 06/17] nvme: Rapid Path Failure Recovery read controller identify fields

[Mohamed Khalfella <mkhalfella@purestorage.com>]

TP8028 Rapid Path Failure Recovery added new fields to controller
identify response. Read CIU (Controller Instance Uniquifier),
CIRN (Controller Instance Random Number), and CCRL (Cross-Controller
Reset Limit) from controller identify response. Expose CIU and CIRN
as sysfs attributes.

Together with CNTLID, CIU and CIRN identify the current instance of the
controller. A controller that is reset gets new values. Exporting them
lets a user tell controller instances apart, correlate an entry in the
CCR log page (which reports ICID and CIU) with a specific controller,
and issue a CCR command by hand when debugging. The values are cached
from the last Identify, so they are also available when the controller
can no longer process admin commands.

Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
---
 Documentation/ABI/stable/sysfs-nvme | 11 +++++++++++
 drivers/nvme/host/core.c            |  4 ++++
 drivers/nvme/host/nvme.h            |  3 +++
 drivers/nvme/host/sysfs.c           | 23 +++++++++++++++++++++++
 4 files changed, 41 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-nvme b/Documentation/ABI/stable/sysfs-nvme
index 9291595f8102..e3395e5730bb 100644
--- a/Documentation/ABI/stable/sysfs-nvme
+++ b/Documentation/ABI/stable/sysfs-nvme
@@ -9,6 +9,17 @@ Description:
 		of the NVMe controller, as reported in the Identify
 		Controller data structure.
 
+What:		/sys/class/nvme/nvmeX/cirn
+What:		/sys/class/nvme/nvmeX/ciu
+Date:		October 2026
+KernelVersion:	7.5
+Contact:	Mohamed Khalfella <mkhalfella@purestorage.com>
+Description:
+		Shows CIRN (Controller Instance Random Number) and CIU
+		(Controller Instance Uniquifier) of the current instance
+		of the NVMe controller as reported by Identify Controller
+		data structure.
+
 What:		/sys/class/nvme/nvmeX/cntlid
 Date:		February 2016
 KernelVersion:	4.6
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 03671bba1754..38b27d8db011 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3693,6 +3693,10 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->crdt[1] = le16_to_cpu(id->crdt2);
 	ctrl->crdt[2] = le16_to_cpu(id->crdt3);
 
+	ctrl->ciu = id->ciu;
+	ctrl->cirn = le64_to_cpu(id->cirn);
+	ctrl->ccrl = id->ccrl;
+
 	ctrl->oacs = le16_to_cpu(id->oacs);
 	ctrl->oncs = le16_to_cpu(id->oncs);
 	ctrl->mtfa = le16_to_cpu(id->mtfa);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 82cdc7d32b22..0c87072c5265 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -401,11 +401,14 @@ struct nvme_ctrl {
 	u16 crdt[3];
 	u16 oncs;
 	u8 dmrl;
+	u8 ciu;
 	u32 dmrsl;
+	u64 cirn;
 	u16 oacs;
 	u16 sqsize;
 	u32 max_namespaces;
 	atomic_t abort_limit;
+	u8 ccrl;
 	u8 vwc;
 	u32 vs;
 	u32 sgls;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 10018c6356b6..5b549a0513c6 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -491,6 +491,27 @@ nvme_show_int_function(queue_count);
 nvme_show_int_function(sqsize);
 nvme_show_int_function(kato);
 
+static ssize_t nvme_sysfs_ciu_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%02x\n", ctrl->ciu);
+}
+static DEVICE_ATTR(ciu, S_IRUSR, nvme_sysfs_ciu_show, NULL);
+
+static ssize_t nvme_sysfs_cirn_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%016llx\n", ctrl->cirn);
+}
+static DEVICE_ATTR(cirn, S_IRUSR, nvme_sysfs_cirn_show, NULL);
+
+
 static ssize_t nvme_sysfs_delete(struct device *dev,
 				struct device_attribute *attr, const char *buf,
 				size_t count)
@@ -943,6 +964,8 @@ static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_numa_node.attr,
 	&dev_attr_queue_count.attr,
 	&dev_attr_sqsize.attr,
+	&dev_attr_ciu.attr,
+	&dev_attr_cirn.attr,
 	&dev_attr_hostnqn.attr,
 	&dev_attr_hostid.attr,
 	&dev_attr_ctrl_loss_tmo.attr,
-- 
2.56.0