xtensa: virt: add defconfig and DTS

Add defconfig and DTS for a virt board. Defconfig enables PCIe host and
a number of virtio devices. DTS routes legacy PCI IRQs to the first four
level-triggered external IRQ lines. CPU core with edge-triggered IRQs
among the first four may need a custom DTS to work correctly.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/boot/dts/virt.dts

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+
+/ {
+	compatible = "cdns,xtensa-iss";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	interrupt-parent = <&pic>;
+
+	chosen {
+		bootargs = "console=ttyS0,115200n8 debug";
+	};
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x00000000 0x80000000>;
+	};
+
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		cpu@0 {
+			compatible = "cdns,xtensa-cpu";
+			reg = <0>;
+			clocks = <&osc>;
+		};
+	};
+
+	clocks {
+		osc: osc {
+			#clock-cells = <0>;
+			compatible = "fixed-clock";
+			clock-frequency = <40000000>;
+		};
+	};
+
+	pic: pic {
+		compatible = "cdns,xtensa-pic";
+		/* one cell: internal irq number,
+		 * two cells: second cell == 0: internal irq number
+		 *            second cell == 1: external irq number
+		 */
+		#address-cells = <0>;
+		#interrupt-cells = <2>;
+		interrupt-controller;
+	};
+
+	pci {
+		compatible = "pci-host-ecam-generic";
+		device_type = "pci";
+		#address-cells = <3>;
+		#size-cells = <2>;
+		#interrupt-cells = <0x1>;
+
+		bus-range = <0x0 0x3f>;
+		reg = <0xc0000000 0x04000000>;
+
+		     // BUS_ADDRESS(3)  CPU_PHYSICAL(1)  SIZE(2)
+		ranges = <0x01000000 0x0 0xc4000000  0xc4000000  0x0 0x04000000>,
+			 <0x02000000 0x0 0xc8000000  0xc8000000  0x0 0x18000000>;
+
+		     // PCI_DEVICE(3)  INT#(1)  CONTROLLER(PHANDLE)  CONTROLLER_DATA(2)
+		interrupt-map = <
+			0x0000 0x0 0x0  0x1  &pic  0x0 0x1
+			0x0800 0x0 0x0  0x1  &pic  0x1 0x1
+			0x1000 0x0 0x0  0x1  &pic  0x2 0x1
+			0x1800 0x0 0x0  0x1  &pic  0x3 0x1
+			>;
+
+		interrupt-map-mask = <0x1800 0x0 0x0  0x7>;
+	};
+};

arch/xtensa/configs/virt_defconfig

+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ_IDLE=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_PREEMPT=y
+CONFIG_IRQ_TIME_ACCOUNTING=y
+CONFIG_BSD_PROCESS_ACCT=y
+CONFIG_MEMCG=y
+CONFIG_CGROUP_FREEZER=y
+CONFIG_CGROUP_DEVICE=y
+CONFIG_CGROUP_CPUACCT=y
+CONFIG_CGROUP_DEBUG=y
+CONFIG_NAMESPACES=y
+CONFIG_SCHED_AUTOGROUP=y
+CONFIG_RELAY=y
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_EXPERT=y
+CONFIG_SYSCTL_SYSCALL=y
+CONFIG_KALLSYMS_ALL=y
+CONFIG_PERF_EVENTS=y
+CONFIG_XTENSA_VARIANT_DC233C=y
+CONFIG_XTENSA_UNALIGNED_USER=y
+CONFIG_VECTORS_OFFSET=0x00002000
+CONFIG_XTENSA_KSEG_512M=y
+CONFIG_HIGHMEM=y
+CONFIG_CMDLINE_BOOL=y
+CONFIG_CMDLINE="console=ttyS0,115200n8 ip=dhcp root=/dev/nfs rw debug memmap=0x80000000@0"
+CONFIG_USE_OF=y
+CONFIG_BUILTIN_DTB_SOURCE="virt"
+# CONFIG_PARSE_BOOTPARAM is not set
+CONFIG_JUMP_LABEL=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+# CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
+# CONFIG_COMPACTION is not set
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+CONFIG_IP_MULTICAST=y
+CONFIG_IP_PNP=y
+CONFIG_IP_PNP_DHCP=y
+CONFIG_IP_PNP_BOOTP=y
+CONFIG_IP_PNP_RARP=y
+# CONFIG_IPV6 is not set
+CONFIG_NETFILTER=y
+# CONFIG_WIRELESS is not set
+CONFIG_PCI=y
+CONFIG_PCI_HOST_GENERIC=y
+CONFIG_UEVENT_HELPER=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+# CONFIG_STANDALONE is not set
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_BLK_DEV_RAM=y
+CONFIG_VIRTIO_BLK=y
+CONFIG_SCSI=y
+CONFIG_BLK_DEV_SD=y
+CONFIG_NETDEVICES=y
+CONFIG_VIRTIO_NET=y
+# CONFIG_ETHERNET is not set
+# CONFIG_WLAN is not set
+CONFIG_INPUT_MOUSEDEV=y
+CONFIG_INPUT_EVDEV=y
+# CONFIG_INPUT_KEYBOARD is not set
+# CONFIG_LEGACY_PTYS is not set
+CONFIG_HW_RANDOM=y
+CONFIG_HW_RANDOM_VIRTIO=y
+# CONFIG_HWMON is not set
+CONFIG_DRM=y
+CONFIG_DRM_VGEM=y
+CONFIG_DRM_VIRTIO_GPU=y
+CONFIG_FB_MODE_HELPERS=y
+# CONFIG_VGA_CONSOLE is not set
+CONFIG_FRAMEBUFFER_CONSOLE=y
+CONFIG_LOGO=y
+# CONFIG_USB_SUPPORT is not set
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_INPUT=y
+# CONFIG_IOMMU_SUPPORT is not set
+CONFIG_EXT3_FS=y
+CONFIG_FANOTIFY=y
+CONFIG_VFAT_FS=y
+CONFIG_PROC_KCORE=y
+CONFIG_TMPFS=y
+CONFIG_TMPFS_POSIX_ACL=y
+CONFIG_NFS_FS=y
+CONFIG_NFS_V4=y
+CONFIG_NFS_SWAP=y
+CONFIG_ROOT_NFS=y
+CONFIG_SUNRPC_DEBUG=y
+CONFIG_NLS_CODEPAGE_437=y
+CONFIG_NLS_ISO8859_1=y
+CONFIG_CRYPTO_ECHAINIV=y
+CONFIG_CRYPTO_DEFLATE=y
+CONFIG_CRYPTO_LZO=y
+CONFIG_CRYPTO_ANSI_CPRNG=y
+CONFIG_CRYPTO_DEV_VIRTIO=y
+CONFIG_FONTS=y
+CONFIG_PRINTK_TIME=y
+CONFIG_DYNAMIC_DEBUG=y
+CONFIG_DEBUG_INFO=y
+CONFIG_MAGIC_SYSRQ=y
+# CONFIG_SCHED_DEBUG is not set
+CONFIG_SCHEDSTATS=y
+CONFIG_DEBUG_RT_MUTEXES=y
+CONFIG_DEBUG_SPINLOCK=y
+CONFIG_DEBUG_MUTEXES=y
+CONFIG_DEBUG_ATOMIC_SLEEP=y
+CONFIG_STACKTRACE=y
+CONFIG_RCU_TRACE=y
+# CONFIG_FTRACE is not set
+# CONFIG_S32C1I_SELFTEST is not set