[PATCH 5/7] nvme: expose subsystem type in sysfs attribute 'subtype'

[Hannes Reinecke]

With unique discovery controller NQNs we cannot distinguish the
subsystem type by the NQN alone, but need to check the subsystem
type, too.
So expose the subsystem type in a new sysfs attribute 'subtype'.

Signed-off-by: Hannes Reinecke <hare at suse.de>
Reviewed-by: Chaitanya Kulkarni <kch at nvidia.com>
---
 drivers/nvme/host/core.c | 27 +++++++++++++++++++++++++++
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 28 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e486845d2c7e..1ed1b7be2812 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2598,6 +2598,24 @@ static ssize_t nvme_subsys_show_nqn(struct device *dev,
 }
 static SUBSYS_ATTR_RO(subsysnqn, S_IRUGO, nvme_subsys_show_nqn);
 
+static ssize_t nvme_subsys_show_subtype(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct nvme_subsystem *subsys =
+		container_of(dev, struct nvme_subsystem, dev);
+
+	switch (subsys->subtype) {
+	case NVME_NQN_DISC:
+		return sysfs_emit(buf, "discovery\n");
+	case NVME_NQN_NVME:
+		return sysfs_emit(buf, "nvm\n");
+	default:
+		return sysfs_emit(buf, "reserved\n");
+	}
+}
+static SUBSYS_ATTR_RO(subtype, S_IRUGO, nvme_subsys_show_subtype);
+
 #define nvme_subsys_show_str_function(field)				\
 static ssize_t subsys_##field##_show(struct device *dev,		\
 			    struct device_attribute *attr, char *buf)	\
@@ -2618,6 +2636,7 @@ static struct attribute *nvme_subsys_attrs[] = {
 	&subsys_attr_serial.attr,
 	&subsys_attr_firmware_rev.attr,
 	&subsys_attr_subsysnqn.attr,
+	&subsys_attr_subtype.attr,
 #ifdef CONFIG_NVME_MULTIPATH
 	&subsys_attr_iopolicy.attr,
 #endif
@@ -2688,6 +2707,14 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 	memcpy(subsys->firmware_rev, id->fr, sizeof(subsys->firmware_rev));
 	subsys->vendor_id = le16_to_cpu(id->vid);
 	subsys->cmic = id->cmic;
+
+	/* Versions prior to 1.4 don't necessarily report a valid type */
+	if (id->cntrltype == NVME_CTRL_DISC ||
+	    !strcmp(subsys->subnqn, NVME_DISC_SUBSYS_NAME))
+		subsys->subtype = NVME_NQN_DISC;
+	else
+		subsys->subtype = NVME_NQN_NVME;
+
 	subsys->awupf = le16_to_cpu(id->awupf);
 #ifdef CONFIG_NVME_MULTIPATH
 	subsys->iopolicy = NVME_IOPOLICY_NUMA;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 9871c0c9374c..2c7a77f600f8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -366,6 +366,7 @@ struct nvme_subsystem {
 	char			model[40];
 	char			firmware_rev[8];
 	u8			cmic;
+	enum nvme_subsys_type	subtype;
 	u16			vendor_id;
 	u16			awupf;	/* 0's based awupf value. */
 	struct ida		ns_ida;
-- 
2.29.2