PCI: designware-ep: Pre-allocate memory for MSI in dw_pcie_ep_init

Certain SoCs need to map the MSI address in raise_irq.
To map an address, you first need to call pci_epc_mem_alloc_addr(),
however, pci_epc_mem_alloc_addr() calls ioremap() (which can sleep).

Since raise_irq is only called from atomic context, we can't call
pci_epc_mem_alloc_addr() from raise_irq.

Pre-allocate a page in dw_pcie_ep_init(), so that this page can later
be used to map/unmap the MSI address in raise_irq.
Tested-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Joao Pinto <jpinto@synopsys.com>

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

@@ -286,6 +286,9 @@ void dw_pcie_ep_exit(struct dw_pcie_ep *ep)
 {
 	struct pci_epc *epc = ep->epc;
 
+	pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
+			      epc->mem->page_size);
+
 	pci_epc_mem_exit(epc);
 }
 
@@ -341,6 +344,13 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 		return ret;
 	}
 
+	ep->msi_mem = pci_epc_mem_alloc_addr(epc, &ep->msi_mem_phys,
+					     epc->mem->page_size);
+	if (!ep->msi_mem) {
+		dev_err(dev, "Failed to reserve memory for MSI\n");
+		return -ENOMEM;
+	}
+
 	ep->epc = epc;
 	epc_set_drvdata(epc, ep);
 	dw_pcie_setup(pci);

drivers/pci/dwc/pcie-designware.h

@@ -198,6 +198,8 @@ struct dw_pcie_ep {
 	unsigned long		ob_window_map;
 	u32			num_ib_windows;
 	u32			num_ob_windows;
+	void __iomem		*msi_mem;
+	phys_addr_t		msi_mem_phys;
 };
 
 struct dw_pcie_ops {