devlink: print controller prefix for non-zero controller

The controller prefix (c<N>) in phys_port_name is currently restricted
to external host controllers. This layout sufficed when DPUs only had a
single local controller and one or more external host controllers.

However, newer devices can have multiple controllers within the DPU
itself, even within a single host environment. To support these
topologies, allow drivers to report the controller number regardless of
the "external" flag status. Any non-zero controller number will now be
explicitly reported, even for single-host or local DPU controllers.
Existing ports with controller=0 are unaffected.

Update documentation and kdoc to clarify that a non-zero controller
number does not require the external flag to be set.

Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260702111726.816985-2-tariqt@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

3 files changed, 15 insertions, 6 deletions

diff --git a/Documentation/networking/devlink/devlink-port.rst b/Documentation/networking/devlink/devlink-port.rst
index 18aca77006d5..fe2cfee3e2a6 100644
--- a/Documentation/networking/devlink/devlink-port.rst
+++ b/Documentation/networking/devlink/devlink-port.rst
@@ -107,6 +107,15 @@ doesn't have the eswitch. Local controller (identified by controller number = 0)
 has the eswitch. The Devlink instance on the local controller has eswitch
 devlink ports for both the controllers.
 
+A non-zero controller number may also be used for ports that are not external.
+For example, a SmartNIC may have additional local PCI physical functions
+that are managed by the eswitch but are not on an external host. These
+ports use a non-zero controller number to distinguish them from the eswitch
+manager's own functions, while the external flag remains unset.
+
+The ``phys_port_name`` includes the controller prefix (``c<controller_num>``)
+whenever the controller number is non-zero, regardless of the external flag.
+
 Function configuration
 ======================
 
diff --git a/include/net/devlink.h b/include/net/devlink.h
index ffe1ad5fb70b..4830aba4087a 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -36,7 +36,7 @@ struct devlink_port_phys_attrs {
  * struct devlink_port_pci_pf_attrs - devlink port's PCI PF attributes
  * @controller: Associated controller number
  * @pf: associated PCI function number for the devlink port instance
- * @external: when set, indicates if a port is for an external controller
+ * @external: when set, indicates if a port is for an external host controller.
  */
 struct devlink_port_pci_pf_attrs {
 	u32 controller;
@@ -50,7 +50,7 @@ struct devlink_port_pci_pf_attrs {
  * @pf: associated PCI function number for the devlink port instance
  * @vf: associated PCI VF number of a PF for the devlink port instance;
  *	VF number starts from 0 for the first PCI virtual function
- * @external: when set, indicates if a port is for an external controller
+ * @external: when set, indicates if a port is for an external host controller.
  */
 struct devlink_port_pci_vf_attrs {
 	u32 controller;
@@ -64,7 +64,7 @@ struct devlink_port_pci_vf_attrs {
  * @controller: Associated controller number
  * @sf: associated SF number of a PF for the devlink port instance
  * @pf: associated PCI function number for the devlink port instance
- * @external: when set, indicates if a port is for an external controller
+ * @external: when set, indicates if a port is for an external host controller.
  */
 struct devlink_port_pci_sf_attrs {
 	u32 controller;
diff --git a/net/devlink/port.c b/net/devlink/port.c
index c268afefaed7..dc82cac68e7d 100644
--- a/net/devlink/port.c
+++ b/net/devlink/port.c
@@ -1529,7 +1529,7 @@ static int __devlink_port_phys_port_name_get(struct devlink_port *devlink_port,
 		WARN_ON(1);
 		return -EINVAL;
 	case DEVLINK_PORT_FLAVOUR_PCI_PF:
-		if (attrs->pci_pf.external) {
+		if (attrs->pci_pf.external || attrs->pci_pf.controller) {
 			n = snprintf(name, len, "c%u", attrs->pci_pf.controller);
 			if (n >= len)
 				return -EINVAL;
@@ -1539,7 +1539,7 @@ static int __devlink_port_phys_port_name_get(struct devlink_port *devlink_port,
 		n = snprintf(name, len, "pf%u", attrs->pci_pf.pf);
 		break;
 	case DEVLINK_PORT_FLAVOUR_PCI_VF:
-		if (attrs->pci_vf.external) {
+		if (attrs->pci_vf.external || attrs->pci_vf.controller) {
 			n = snprintf(name, len, "c%u", attrs->pci_vf.controller);
 			if (n >= len)
 				return -EINVAL;
@@ -1550,7 +1550,7 @@ static int __devlink_port_phys_port_name_get(struct devlink_port *devlink_port,
 			     attrs->pci_vf.pf, attrs->pci_vf.vf);
 		break;
 	case DEVLINK_PORT_FLAVOUR_PCI_SF:
-		if (attrs->pci_sf.external) {
+		if (attrs->pci_sf.external || attrs->pci_sf.controller) {
 			n = snprintf(name, len, "c%u", attrs->pci_sf.controller);
 			if (n >= len)
 				return -EINVAL;