PCI: dwc: ep: Introduce dw_pcie_ep_cleanup() API for drivers supporting PERST#

For DWC glue drivers supporting PERST# (currently Qcom and Tegra194), some
of the DWC resources like eDMA should be cleaned up during the PERST#
assert time.

So let's introduce a dw_pcie_ep_cleanup() API that could be called by these
drivers to cleanup the DWC specific resources. Currently, it just removes
eDMA.

Closes: https://lore.kernel.org/linux-pci/ZWYmX8Y%2F7Q9WMxES@x1-carbon
Link: https://lore.kernel.org/linux-pci/20240327-pci-dbi-rework-v12-5-082625472414@linaro.org
Reported-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>

Author: Mani-Sadhasivam

drivers/pci/controller/dwc/pcie-designware-ep.c

@@ -619,6 +619,22 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
 	return 0;
 }
 
+/**
+ * dw_pcie_ep_cleanup - Cleanup DWC EP resources after fundamental reset
+ * @ep: DWC EP device
+ *
+ * Cleans up the DWC EP specific resources like eDMA etc... after fundamental
+ * reset like PERST#. Note that this API is only applicable for drivers
+ * supporting PERST# or any other methods of fundamental reset.
+ */
+void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+
+	dw_pcie_edma_remove(pci);
+}
+EXPORT_SYMBOL_GPL(dw_pcie_ep_cleanup);
+
 /**
  * dw_pcie_ep_deinit - Deinitialize the endpoint device
  * @ep: DWC EP device
@@ -628,10 +644,9 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
  */
 void dw_pcie_ep_deinit(struct dw_pcie_ep *ep)
 {
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 	struct pci_epc *epc = ep->epc;
 
-	dw_pcie_edma_remove(pci);
+	dw_pcie_ep_cleanup(ep);
 
 	pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
 			      epc->mem->window.page_size);

drivers/pci/controller/dwc/pcie-designware.h

@@ -672,6 +672,7 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep);
 int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep);
 void dw_pcie_ep_init_notify(struct dw_pcie_ep *ep);
 void dw_pcie_ep_deinit(struct dw_pcie_ep *ep);
+void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep);
 int dw_pcie_ep_raise_intx_irq(struct dw_pcie_ep *ep, u8 func_no);
 int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
 			     u8 interrupt_num);
@@ -705,6 +706,10 @@ static inline void dw_pcie_ep_deinit(struct dw_pcie_ep *ep)
 {
 }
 
+static inline void dw_pcie_ep_cleanup(struct dw_pcie_ep *ep)
+{
+}
+
 static inline int dw_pcie_ep_raise_intx_irq(struct dw_pcie_ep *ep, u8 func_no)
 {
 	return 0;

drivers/pci/controller/dwc/pcie-qcom-ep.c

@@ -507,6 +507,7 @@ static void qcom_pcie_perst_assert(struct dw_pcie *pci)
 		return;
 	}
 
+	dw_pcie_ep_cleanup(&pci->ep);
 	qcom_pcie_disable_resources(pcie_ep);
 	pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED;
 }

drivers/pci/controller/dwc/pcie-tegra194.c

@@ -1715,6 +1715,8 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie)
 	if (ret)
 		dev_err(pcie->dev, "Failed to go Detect state: %d\n", ret);
 
+	dw_pcie_ep_cleanup(&pcie->pci.ep);
+
 	reset_control_assert(pcie->core_rst);
 
 	tegra_pcie_disable_phy(pcie);