PCI/ACPI: Add Ampere Altra SOC MCFG quirk

Ampere Altra SOC supports only 32-bit ECAM reads.  Add an MCFG quirk for
the platform.

Link: https://lore.kernel.org/r/1596751055-12316-1-git-send-email-tuanphan@os.amperecomputing.comSigned-off-by: NTuan Phan <tuanphan@os.amperecomputing.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/acpi/pci_mcfg.c

@@ -142,6 +142,26 @@ static struct mcfg_fixup mcfg_quirks[] = {
 	XGENE_V2_ECAM_MCFG(4, 0),
 	XGENE_V2_ECAM_MCFG(4, 1),
 	XGENE_V2_ECAM_MCFG(4, 2),
+
+#define ALTRA_ECAM_QUIRK(rev, seg) \
+	{ "Ampere", "Altra   ", rev, seg, MCFG_BUS_ANY, &pci_32b_read_ops }
+
+	ALTRA_ECAM_QUIRK(1, 0),
+	ALTRA_ECAM_QUIRK(1, 1),
+	ALTRA_ECAM_QUIRK(1, 2),
+	ALTRA_ECAM_QUIRK(1, 3),
+	ALTRA_ECAM_QUIRK(1, 4),
+	ALTRA_ECAM_QUIRK(1, 5),
+	ALTRA_ECAM_QUIRK(1, 6),
+	ALTRA_ECAM_QUIRK(1, 7),
+	ALTRA_ECAM_QUIRK(1, 8),
+	ALTRA_ECAM_QUIRK(1, 9),
+	ALTRA_ECAM_QUIRK(1, 10),
+	ALTRA_ECAM_QUIRK(1, 11),
+	ALTRA_ECAM_QUIRK(1, 12),
+	ALTRA_ECAM_QUIRK(1, 13),
+	ALTRA_ECAM_QUIRK(1, 14),
+	ALTRA_ECAM_QUIRK(1, 15),
 };
 
 static char mcfg_oem_id[ACPI_OEM_ID_SIZE];

drivers/pci/ecam.c

@@ -168,4 +168,14 @@ const struct pci_ecam_ops pci_32b_ops = {
 		.write		= pci_generic_config_write32,
 	}
 };
+
+/* ECAM ops for 32-bit read only (non-compliant) */
+const struct pci_ecam_ops pci_32b_read_ops = {
+	.bus_shift	= 20,
+	.pci_ops	= {
+		.map_bus	= pci_ecam_map_bus,
+		.read		= pci_generic_config_read32,
+		.write		= pci_generic_config_write,
+	}
+};
 #endif

include/linux/pci-ecam.h

@@ -51,6 +51,7 @@ extern const struct pci_ecam_ops pci_generic_ecam_ops;
 
 #if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
 extern const struct pci_ecam_ops pci_32b_ops;	/* 32-bit accesses only */
+extern const struct pci_ecam_ops pci_32b_read_ops; /* 32-bit read only */
 extern const struct pci_ecam_ops hisi_pcie_ops;	/* HiSilicon */
 extern const struct pci_ecam_ops thunder_pem_ecam_ops; /* Cavium ThunderX 1.x & 2.x */
 extern const struct pci_ecam_ops pci_thunder_ecam_ops; /* Cavium ThunderX 1.x */