ARM: Add a new arch + board for QEMU's 'virt' machine

This board builds an U-Boot binary that is bootable with QEMU's 'virt'
machine on ARM. The minimal QEMU command line is:

    qemu-system-arm -machine virt,highmem=off -bios u-boot.bin

(Note that the 'highmem=off' parameter to the 'virt' machine is required for
PCI to work in U-Boot.) This command line enables the following:
    - u-boot.bin loaded and executing in the emulated flash at address 0x0
    - A generated device tree blob placed at the start of RAM
    - A freely configurable amount of RAM, described by the DTB
    - A PL011 serial port, discoverable via the DTB
    - An ARMv7 architected timer
    - PSCI for rebooting the system
    - A generic ECAM-based PCI host controller, discoverable via the DTB

Additionally, QEMU allows plugging a bunch of useful peripherals to the PCI bus.
The following ones are supported by both U-Boot and Linux:

- To add a Serial ATA disk via an Intel ICH9 AHCI controller, pass e.g.:
    -drive if=none,file=disk.img,id=mydisk -device ich9-ahci,id=ahci -device ide-drive,drive=mydisk,bus=ahci.0
- To add an Intel E1000 network adapter, pass e.g.:
    -net nic,model=e1000 -net user
- To add an EHCI-compliant USB host controller, pass e.g.:
    -device usb-ehci,id=ehci
- To add a NVMe disk, pass e.g.:
    -drive if=none,file=disk.img,id=mydisk -device nvme,drive=mydisk,serial=foo

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>

3 files changed, 44 insertions, 0 deletions

diff --git a/board/emulation/qemu-arm/MAINTAINERS b/board/emulation/qemu-arm/MAINTAINERS
new file mode 100644
index 0000000000..a803061ff4
--- /dev/null
+++ b/board/emulation/qemu-arm/MAINTAINERS
@@ -0,0 +1,6 @@
+QEMU ARM 'VIRT' BOARD
+M:	Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+S:	Maintained
+F:	board/emulation/qemu-arm/
+F:	include/configs/qemu-arm.h
+F:	configs/qemu_arm_defconfig
diff --git a/board/emulation/qemu-arm/Makefile b/board/emulation/qemu-arm/Makefile
new file mode 100644
index 0000000000..716a6e9c28
--- /dev/null
+++ b/board/emulation/qemu-arm/Makefile
@@ -0,0 +1,5 @@
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-y	+= qemu-arm.o
diff --git a/board/emulation/qemu-arm/qemu-arm.c b/board/emulation/qemu-arm/qemu-arm.c
new file mode 100644
index 0000000000..e29ba4630f
--- /dev/null
+++ b/board/emulation/qemu-arm/qemu-arm.c
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2017 Tuomas Tynkkynen
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+#include <common.h>
+#include <fdtdec.h>
+
+int board_init(void)
+{
+	return 0;
+}
+
+int dram_init(void)
+{
+	if (fdtdec_setup_memory_size() != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+int dram_init_banksize(void)
+{
+	fdtdec_setup_memory_banksize();
+
+	return 0;
+}
+
+void *board_fdt_blob_setup(void)
+{
+	/* QEMU loads a generated DTB for us at the start of RAM. */
+	return (void *)CONFIG_SYS_SDRAM_BASE;
+}