PCI: endpoint: Add support to add virtual function in endpoint core

Add support to add virtual function in endpoint core. The virtual
function can only be associated with a physical function instead of a
endpoint controller. Provide APIs to associate a virtual function with
a physical function here.

[weiyongjun1@huawei.com: PCI: endpoint: Fix missing unlock on error in
 pci_epf_add_vepf() - Reported-by: Hulk Robot <hulkci@huawei.com>]

Link: https://lore.kernel.org/r/20210819123343.1951-3-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/endpoint/pci-epc-core.c

@@ -548,7 +548,7 @@ int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf,
 	u32 func_no;
 	int ret = 0;
 
-	if (IS_ERR_OR_NULL(epc))
+	if (IS_ERR_OR_NULL(epc) || epf->is_vf)
 		return -EINVAL;
 
 	if (type == PRIMARY_INTERFACE && epf->epc)

drivers/pci/endpoint/pci-epf-core.c

@@ -62,13 +62,20 @@ EXPORT_SYMBOL_GPL(pci_epf_type_add_cfs);
  */
 void pci_epf_unbind(struct pci_epf *epf)
 {
+	struct pci_epf *epf_vf;
+
 	if (!epf->driver) {
 		dev_WARN(&epf->dev, "epf device not bound to driver\n");
 		return;
 	}
 
 	mutex_lock(&epf->lock);
-	epf->driver->ops->unbind(epf);
+	list_for_each_entry(epf_vf, &epf->pci_vepf, list) {
+		if (epf_vf->is_bound)
+			epf_vf->driver->ops->unbind(epf_vf);
+	}
+	if (epf->is_bound)
+		epf->driver->ops->unbind(epf);
 	mutex_unlock(&epf->lock);
 	module_put(epf->driver->owner);
 }
@@ -83,6 +90,7 @@ EXPORT_SYMBOL_GPL(pci_epf_unbind);
  */
 int pci_epf_bind(struct pci_epf *epf)
 {
+	struct pci_epf *epf_vf;
 	int ret;
 
 	if (!epf->driver) {
@@ -94,13 +102,97 @@ int pci_epf_bind(struct pci_epf *epf)
 		return -EAGAIN;
 
 	mutex_lock(&epf->lock);
+	list_for_each_entry(epf_vf, &epf->pci_vepf, list) {
+		epf_vf->func_no = epf->func_no;
+		epf_vf->epc = epf->epc;
+		epf_vf->sec_epc = epf->sec_epc;
+		ret = epf_vf->driver->ops->bind(epf_vf);
+		if (ret)
+			goto ret;
+		epf_vf->is_bound = true;
+	}
+
 	ret = epf->driver->ops->bind(epf);
+	if (ret)
+		goto ret;
+	epf->is_bound = true;
+
 	mutex_unlock(&epf->lock);
+	return 0;
+
+ret:
+	mutex_unlock(&epf->lock);
+	pci_epf_unbind(epf);
 
 	return ret;
 }
 EXPORT_SYMBOL_GPL(pci_epf_bind);
 
+/**
+ * pci_epf_add_vepf() - associate virtual EP function to physical EP function
+ * @epf_pf: the physical EP function to which the virtual EP function should be
+ *   associated
+ * @epf_vf: the virtual EP function to be added
+ *
+ * A physical endpoint function can be associated with multiple virtual
+ * endpoint functions. Invoke pci_epf_add_epf() to add a virtual PCI endpoint
+ * function to a physical PCI endpoint function.
+ */
+int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
+{
+	u32 vfunc_no;
+
+	if (IS_ERR_OR_NULL(epf_pf) || IS_ERR_OR_NULL(epf_vf))
+		return -EINVAL;
+
+	if (epf_pf->epc || epf_vf->epc || epf_vf->epf_pf)
+		return -EBUSY;
+
+	if (epf_pf->sec_epc || epf_vf->sec_epc)
+		return -EBUSY;
+
+	mutex_lock(&epf_pf->lock);
+	vfunc_no = find_first_zero_bit(&epf_pf->vfunction_num_map,
+				       BITS_PER_LONG);
+	if (vfunc_no >= BITS_PER_LONG) {
+		mutex_unlock(&epf_pf->lock);
+		return -EINVAL;
+	}
+
+	set_bit(vfunc_no, &epf_pf->vfunction_num_map);
+	epf_vf->vfunc_no = vfunc_no;
+
+	epf_vf->epf_pf = epf_pf;
+	epf_vf->is_vf = true;
+
+	list_add_tail(&epf_vf->list, &epf_pf->pci_vepf);
+	mutex_unlock(&epf_pf->lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_epf_add_vepf);
+
+/**
+ * pci_epf_remove_vepf() - remove virtual EP function from physical EP function
+ * @epf_pf: the physical EP function from which the virtual EP function should
+ *   be removed
+ * @epf_vf: the virtual EP function to be removed
+ *
+ * Invoke to remove a virtual endpoint function from the physcial endpoint
+ * function.
+ */
+void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
+{
+	if (IS_ERR_OR_NULL(epf_pf) || IS_ERR_OR_NULL(epf_vf))
+		return;
+
+	mutex_lock(&epf_pf->lock);
+	clear_bit(epf_vf->vfunc_no, &epf_pf->vfunction_num_map);
+	list_del(&epf_vf->list);
+	mutex_unlock(&epf_pf->lock);
+}
+EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
+
 /**
  * pci_epf_free_space() - free the allocated PCI EPF register space
  * @epf: the EPF device from whom to free the memory
@@ -317,6 +409,10 @@ struct pci_epf *pci_epf_create(const char *name)
 		return ERR_PTR(-ENOMEM);
 	}
 
+	/* VFs are numbered starting with 1. So set BIT(0) by default */
+	epf->vfunction_num_map = 1;
+	INIT_LIST_HEAD(&epf->pci_vepf);
+
 	dev = &epf->dev;
 	device_initialize(dev);
 	dev->bus = &pci_epf_bus_type;

include/linux/pci-epf.h

@@ -121,8 +121,10 @@ struct pci_epf_bar {
  * @bar: represents the BAR of EPF device
  * @msi_interrupts: number of MSI interrupts required by this function
  * @msix_interrupts: number of MSI-X interrupts required by this function
- * @func_no: unique function number within this endpoint device
+ * @func_no: unique (physical) function number within this endpoint device
+ * @vfunc_no: unique virtual function number within a physical function
  * @epc: the EPC device to which this EPF device is bound
+ * @epf_pf: the physical EPF device to which this virtual EPF device is bound
  * @driver: the EPF driver to which this EPF device is bound
  * @list: to add pci_epf as a list of PCI endpoint functions to pci_epc
  * @nb: notifier block to notify EPF of any EPC events (like linkup)
@@ -133,6 +135,10 @@ struct pci_epf_bar {
  * @sec_epc_bar: represents the BAR of EPF device associated with secondary EPC
  * @sec_epc_func_no: unique (physical) function number within the secondary EPC
  * @group: configfs group associated with the EPF device
+ * @is_bound: indicates if bind notification to function driver has been invoked
+ * @is_vf: true - virtual function, false - physical function
+ * @vfunction_num_map: bitmap to manage virtual function number
+ * @pci_vepf: list of virtual endpoint functions associated with this function
  */
 struct pci_epf {
 	struct device		dev;
@@ -142,8 +148,10 @@ struct pci_epf {
 	u8			msi_interrupts;
 	u16			msix_interrupts;
 	u8			func_no;
+	u8			vfunc_no;
 
 	struct pci_epc		*epc;
+	struct pci_epf		*epf_pf;
 	struct pci_epf_driver	*driver;
 	struct list_head	list;
 	struct notifier_block   nb;
@@ -156,6 +164,10 @@ struct pci_epf {
 	struct pci_epf_bar	sec_epc_bar[6];
 	u8			sec_epc_func_no;
 	struct config_group	*group;
+	unsigned int		is_bound;
+	unsigned int		is_vf;
+	unsigned long		vfunction_num_map;
+	struct list_head	pci_vepf;
 };
 
 /**
@@ -199,4 +211,6 @@ int pci_epf_bind(struct pci_epf *epf);
 void pci_epf_unbind(struct pci_epf *epf);
 struct config_group *pci_epf_type_add_cfs(struct pci_epf *epf,
 					  struct config_group *group);
+int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);
+void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);
 #endif /* __LINUX_PCI_EPF_H */