PCI: endpoint: Add support to associate secondary EPC with EPF

In the case of standard endpoint functions, only one endpoint controller
(EPC) will be associated with an endpoint function (EPF). However for
providing NTB (non transparent bridge) functionality, two EPCs should be
associated with a single EPF.  Add support to associate secondary EPC with
EPF. This is in preparation for adding NTB endpoint function driver.

Link: https://lore.kernel.org/r/20210201195809.7342-7-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 36 insertions, 11 deletions

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index ea7e7465ce7a..3693eca5b030 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -493,21 +493,28 @@ EXPORT_SYMBOL_GPL(pci_epc_write_header);
  * pci_epc_add_epf() - bind PCI endpoint function to an endpoint controller
  * @epc: the EPC device to which the endpoint function should be added
  * @epf: the endpoint function to be added
+ * @type: Identifies if the EPC is connected to the primary or secondary
+ *        interface of EPF
  *
  * A PCI endpoint device can have one or more functions. In the case of PCIe,
  * the specification allows up to 8 PCIe endpoint functions. Invoke
  * pci_epc_add_epf() to add a PCI endpoint function to an endpoint controller.
  */
-int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf)
+int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf,
+		    enum pci_epc_interface_type type)
 {
+	struct list_head *list;
 	u32 func_no;
 	int ret = 0;
 
-	if (epf->epc)
+	if (IS_ERR_OR_NULL(epc))
+		return -EINVAL;
+
+	if (type == PRIMARY_INTERFACE && epf->epc)
 		return -EBUSY;
 
-	if (IS_ERR(epc))
-		return -EINVAL;
+	if (type == SECONDARY_INTERFACE && epf->sec_epc)
+		return -EBUSY;
 
 	mutex_lock(&epc->lock);
 	func_no = find_first_zero_bit(&epc->function_num_map,
@@ -524,11 +531,17 @@ int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf)
 	}
 
 	set_bit(func_no, &epc->function_num_map);
-	epf->func_no = func_no;
-	epf->epc = epc;
-
-	list_add_tail(&epf->list, &epc->pci_epf);
+	if (type == PRIMARY_INTERFACE) {
+		epf->func_no = func_no;
+		epf->epc = epc;
+		list = &epf->list;
+	} else {
+		epf->sec_epc_func_no = func_no;
+		epf->sec_epc = epc;
+		list = &epf->sec_epc_list;
+	}
 
+	list_add_tail(list, &epc->pci_epf);
 ret:
 	mutex_unlock(&epc->lock);
 
@@ -543,14 +556,26 @@ EXPORT_SYMBOL_GPL(pci_epc_add_epf);
  *
  * Invoke to remove PCI endpoint function from the endpoint controller.
  */
-void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf)
+void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
+			enum pci_epc_interface_type type)
 {
+	struct list_head *list;
+	u32 func_no = 0;
+
 	if (!epc || IS_ERR(epc) || !epf)
 		return;
 
+	if (type == PRIMARY_INTERFACE) {
+		func_no = epf->func_no;
+		list = &epf->list;
+	} else {
+		func_no = epf->sec_epc_func_no;
+		list = &epf->sec_epc_list;
+	}
+
 	mutex_lock(&epc->lock);
-	clear_bit(epf->func_no, &epc->function_num_map);
-	list_del(&epf->list);
+	clear_bit(func_no, &epc->function_num_map);
+	list_del(list);
 	epf->epc = NULL;
 	mutex_unlock(&epc->lock);
 }