PCI: endpoint: Add BME notifier support

Add support to notify the EPF device about the Bus Master Enable (BME)
event received by the EPC device from the Root complex.

Link: https://lore.kernel.org/r/20230602114756.36586-6-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kishon Vijay Abraham I <kishon@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

Author: Mani-Sadhasivam

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

@@ -758,6 +758,32 @@ void pci_epc_init_notify(struct pci_epc *epc)
 }
 EXPORT_SYMBOL_GPL(pci_epc_init_notify);
 
+/**
+ * pci_epc_bme_notify() - Notify the EPF device that the EPC device has received
+ *			  the BME event from the Root complex
+ * @epc: the EPC device that received the BME event
+ *
+ * Invoke to Notify the EPF device that the EPC device has received the Bus
+ * Master Enable (BME) event from the Root complex
+ */
+void pci_epc_bme_notify(struct pci_epc *epc)
+{
+	struct pci_epf *epf;
+
+	if (!epc || IS_ERR(epc))
+		return;
+
+	mutex_lock(&epc->list_lock);
+	list_for_each_entry(epf, &epc->pci_epf, list) {
+		mutex_lock(&epf->lock);
+		if (epf->event_ops && epf->event_ops->bme)
+			epf->event_ops->bme(epf);
+		mutex_unlock(&epf->lock);
+	}
+	mutex_unlock(&epc->list_lock);
+}
+EXPORT_SYMBOL_GPL(pci_epc_bme_notify);
+
 /**
  * pci_epc_destroy() - destroy the EPC device
  * @epc: the EPC device that has to be destroyed

include/linux/pci-epc.h

@@ -205,6 +205,7 @@ int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf,
 void pci_epc_linkup(struct pci_epc *epc);
 void pci_epc_linkdown(struct pci_epc *epc);
 void pci_epc_init_notify(struct pci_epc *epc);
+void pci_epc_bme_notify(struct pci_epc *epc);
 void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
 			enum pci_epc_interface_type type);
 int pci_epc_write_header(struct pci_epc *epc, u8 func_no, u8 vfunc_no,

include/linux/pci-epf.h

@@ -72,11 +72,13 @@ struct pci_epf_ops {
  * @core_init: Callback for the EPC initialization complete event
  * @link_up: Callback for the EPC link up event
  * @link_down: Callback for the EPC link down event
+ * @bme: Callback for the EPC BME (Bus Master Enable) event
  */
 struct pci_epc_event_ops {
 	int (*core_init)(struct pci_epf *epf);
 	int (*link_up)(struct pci_epf *epf);
 	int (*link_down)(struct pci_epf *epf);
+	int (*bme)(struct pci_epf *epf);
 };
 
 /**