PCI: dwc: endpoint: Implement the pci_epc_ops::align_addr() operation

The function dw_pcie_prog_outbound_atu() used to program outbound ATU
entries for mapping RC PCI addresses to local CPU addresses does not
allow PCI addresses that are not aligned to the value of region_align
of struct dw_pcie. This value is determined from the iATU hardware
registers during probing of the iATU (done by dw_pcie_iatu_detect()).
This value is thus valid for all DWC PCIe controllers, and valid
regardless of the hardware configuration used when synthesizing the
DWC PCIe controller.

Implement the ->align_addr() endpoint controller operation to allow
this mapping alignment to be transparently handled by endpoint function
drivers through the function pci_epc_mem_map().

Link: https://lore.kernel.org/linux-pci/20241012113246.95634-7-dlemoal@kernel.org
Link: https://lore.kernel.org/linux-pci/20241015090712.112674-1-dlemoal@kernel.org
Link: https://lore.kernel.org/linux-pci/20241017132052.4014605-5-cassel@kernel.org
Co-developed-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
[mani: squashed the patch that changed phy_addr_t to u64]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[kwilczynski: squashed patch that updated the pci_size variable]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Author: damien-lemoal

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

@@ -268,6 +268,20 @@ static int dw_pcie_find_index(struct dw_pcie_ep *ep, phys_addr_t addr,
 	return -EINVAL;
 }
 
+static u64 dw_pcie_ep_align_addr(struct pci_epc *epc, u64 pci_addr,
+				 size_t *pci_size, size_t *offset)
+{
+	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	u64 mask = pci->region_align - 1;
+	size_t ofst = pci_addr & mask;
+
+	*pci_size = ALIGN(ofst + *pci_size, epc->mem->window.page_size);
+	*offset = ofst;
+
+	return pci_addr & ~mask;
+}
+
 static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 				  phys_addr_t addr)
 {
@@ -444,6 +458,7 @@ static const struct pci_epc_ops epc_ops = {
 	.write_header		= dw_pcie_ep_write_header,
 	.set_bar		= dw_pcie_ep_set_bar,
 	.clear_bar		= dw_pcie_ep_clear_bar,
+	.align_addr		= dw_pcie_ep_align_addr,
 	.map_addr		= dw_pcie_ep_map_addr,
 	.unmap_addr		= dw_pcie_ep_unmap_addr,
 	.set_msi		= dw_pcie_ep_set_msi,