PCI: endpoint: Introduce 'epc_deinit' event and notify the EPF drivers

As like the 'epc_init' event, that is used to signal the EPF drivers about
the EPC initialization, let's introduce 'epc_deinit' event that is used to
signal EPC deinitialization.

The EPC deinitialization applies only when any sort of fundamental reset
is supported by the endpoint controller as per the PCIe spec.

Reference: PCIe r6.0, sec 4.2.5.9.1 and 6.6.1.

Currently, some EPC drivers like pcie-qcom-ep and pcie-tegra194 support
PERST# as the fundamental reset. So the 'deinit' event will be notified to
the EPF drivers when PERST# assert happens in the above mentioned EPC
drivers.

The EPF drivers, on receiving the event through the epc_deinit() callback
should reset the EPF state machine and also cleanup any configuration that
got affected by the fundamental reset like BAR, DMA etc...

This change also warrants skipping the cleanups in unbind() if already done
in epc_deinit().

Link: https://lore.kernel.org/r/20240606-pci-deinit-v1-2-4395534520dc@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 11115cd0fe5b..85bdf2adb760 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -197,6 +197,8 @@ struct pci_epc_features {
 
 #define to_pci_epc(device) container_of((device), struct pci_epc, dev)
 
+#ifdef CONFIG_PCI_ENDPOINT
+
 #define pci_epc_create(dev, ops)    \
 		__pci_epc_create((dev), (ops), THIS_MODULE)
 #define devm_pci_epc_create(dev, ops)    \
@@ -226,6 +228,7 @@ 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_notify_pending_init(struct pci_epc *epc, struct pci_epf *epf);
+void pci_epc_deinit_notify(struct pci_epc *epc);
 void pci_epc_bus_master_enable_notify(struct pci_epc *epc);
 void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
 			enum pci_epc_interface_type type);
@@ -272,4 +275,14 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
 				     phys_addr_t *phys_addr, size_t size);
 void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
 			   void __iomem *virt_addr, size_t size);
+
+#else
+static inline void pci_epc_init_notify(struct pci_epc *epc)
+{
+}
+
+static inline void pci_epc_deinit_notify(struct pci_epc *epc)
+{
+}
+#endif /* CONFIG_PCI_ENDPOINT */
 #endif /* __LINUX_PCI_EPC_H */
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index dc759eb7157c..0639d4dc8986 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -71,12 +71,14 @@ struct pci_epf_ops {
 /**
  * struct pci_epc_event_ops - Callbacks for capturing the EPC events
  * @epc_init: Callback for the EPC initialization complete event
+ * @epc_deinit: Callback for the EPC deinitialization event
  * @link_up: Callback for the EPC link up event
  * @link_down: Callback for the EPC link down event
  * @bus_master_enable: Callback for the EPC Bus Master Enable event
  */
 struct pci_epc_event_ops {
 	int (*epc_init)(struct pci_epf *epf);
+	void (*epc_deinit)(struct pci_epf *epf);
 	int (*link_up)(struct pci_epf *epf);
 	int (*link_down)(struct pci_epf *epf);
 	int (*bus_master_enable)(struct pci_epf *epf);