PCI: dwc: Introduce generic controller capabilities interface

Since in addition to the already available iATU unrolled mapping we are
about to add a few more DW PCIe platform-specific capabilities (CDM-check
and generic clocks/resets resources) let's add a generic interface to set
and get the flags indicating their availability. The new interface shall
improve maintainability of the platform-specific code.

Link: https://lore.kernel.org/r/20221113191301.5526-17-Sergey.Semin@baikalelectronics.ruSigned-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

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

@@ -211,7 +211,7 @@ void dw_pcie_write_dbi2(struct dw_pcie *pci, u32 reg, size_t size, u32 val)
 static inline void __iomem *dw_pcie_select_atu(struct dw_pcie *pci, u32 dir,
 					       u32 index)
 {
-	if (pci->iatu_unroll_enabled)
+	if (dw_pcie_cap_is(pci, IATU_UNROLL))
 		return pci->atu_base + PCIE_ATU_UNROLL_BASE(dir, index);
 
 	dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, dir | index);
@@ -591,7 +591,7 @@ static void dw_pcie_iatu_detect_regions(struct dw_pcie *pci)
 	u32 val, min, dir;
 	u64 max;
 
-	if (pci->iatu_unroll_enabled) {
+	if (dw_pcie_cap_is(pci, IATU_UNROLL)) {
 		max_region = min((int)pci->atu_size / 512, 256);
 	} else {
 		dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, 0xFF);
@@ -641,8 +641,9 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
 {
 	struct platform_device *pdev = to_platform_device(pci->dev);
 
-	pci->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pci);
-	if (pci->iatu_unroll_enabled) {
+	if (dw_pcie_iatu_unroll_enabled(pci)) {
+		dw_pcie_cap_set(pci, IATU_UNROLL);
+
 		if (!pci->atu_base) {
 			struct resource *res =
 				platform_get_resource_byname(pdev, IORESOURCE_MEM, "atu");
@@ -664,7 +665,7 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
 
 	dw_pcie_iatu_detect_regions(pci);
 
-	dev_info(pci->dev, "iATU unroll: %s\n", pci->iatu_unroll_enabled ?
+	dev_info(pci->dev, "iATU unroll: %s\n", dw_pcie_cap_is(pci, IATU_UNROLL) ?
 		"enabled" : "disabled");
 
 	dev_info(pci->dev, "iATU regions: %u ob, %u ib, align %uK, limit %lluG\n",

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

@@ -12,6 +12,7 @@
 #define _PCIE_DESIGNWARE_H
 
 #include <linux/bitfield.h>
+#include <linux/bitops.h>
 #include <linux/dma-mapping.h>
 #include <linux/irq.h>
 #include <linux/msi.h>
@@ -43,6 +44,15 @@
 	(__dw_pcie_ver_cmp(_pci, _ver, ==) && \
 	 __dw_pcie_ver_cmp(_pci, TYPE_ ## _type, >=))
 
+/* DWC PCIe controller capabilities */
+#define DW_PCIE_CAP_IATU_UNROLL		1
+
+#define dw_pcie_cap_is(_pci, _cap) \
+	test_bit(DW_PCIE_CAP_ ## _cap, &(_pci)->caps)
+
+#define dw_pcie_cap_set(_pci, _cap) \
+	set_bit(DW_PCIE_CAP_ ## _cap, &(_pci)->caps)
+
 /* Parameters for the waiting for link up routine */
 #define LINK_WAIT_MAX_RETRIES		10
 #define LINK_WAIT_USLEEP_MIN		90000
@@ -317,10 +327,10 @@ struct dw_pcie {
 	const struct dw_pcie_ops *ops;
 	u32			version;
 	u32			type;
+	unsigned long		caps;
 	int			num_lanes;
 	int			link_gen;
 	u8			n_fts[2];
-	bool			iatu_unroll_enabled: 1;
 };
 
 #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)