sfc: Associate primary and secondary functions of controller

The primary function of an EF10 controller will share its clock
device with other functions in the same domain (which we call
secondary functions).  To this end, we need to associate functions
on the same controller.

We do not control probe order, so allow primary and secondary
functions to appear in any order.  Maintain global lists of all
primary functions and of unassociated secondary functions,
and a list of secondary functions on each primary function.

Use the VPD serial number to tell whether functions are part of the
same controller.  VPD will not be readable by virtual functions, so
this may need to be revisited later.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index be8a616..653b878 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -657,6 +657,13 @@
  * struct efx_nic - an Efx NIC
  * @name: Device name (net device name or bus id before net device registered)
  * @pci_dev: The PCI device
+ * @node: List node for maintaning primary/secondary function lists
+ * @primary: &struct efx_nic instance for the primary function of this
+ *	controller.  May be the same structure, and may be %NULL if no
+ *	primary function is bound.  Serialised by rtnl_lock.
+ * @secondary_list: List of &struct efx_nic instances for the secondary PCI
+ *	functions of the controller, if this is for the primary function.
+ *	Serialised by rtnl_lock.
  * @type: Controller type attributes
  * @legacy_irq: IRQ number
  * @workqueue: Workqueue for port reconfigures and the HW monitor.
@@ -786,6 +793,9 @@
 	/* The following fields should be written very rarely */
 
 	char name[IFNAMSIZ];
+	struct list_head node;
+	struct efx_nic *primary;
+	struct list_head secondary_list;
 	struct pci_dev *pci_dev;
 	unsigned int port_num;
 	const struct efx_nic_type *type;