[PATCH v3 14/19] board: emulation: Add qemu-loongarch

From: Jiaxun Yang <[email protected]>

Yet another generic QEMU VIRT machine.

LoongArch QEMU splits the main RAM into two parts: the first 512M is
placed at 0x0, and the rest is placed at 0x8000000. FDT locates at
0x100000. BIOS is mapped to the first flash mapped to 0x1c000000, where
U-Boot starts execution.

Signed-off-by: Jiaxun Yang <[email protected]>
Signed-off-by: Yao Zi <[email protected]>
---

Changed from v2
- Add board-level documentation for qemu-loongarch
- Mention the memory layout and booting process in commit message
- Move TARGET_QEMU_LOONGARCH_VIRT to
  board/emulation/qemu-loongarch/Kconfig
- Drop duplicated selection of BOARD_LATE_INIT in
  TARGET_QEMU_LOONGARCH_VIRT
- Explain why RAM is limited to the lowest 4GiB
- Drop unused board_init()
- Rework comment in board_fdt_blob_setup()
- Define FDT address, 0x100000, as a meaningful constant
- Clarify how CFG_SYS_INIT_RAM_[ADDR,SIZE] are chosen
- Add myself to MAINTAINERS

Changed from v1
- Remove dynamic setup for environment variables

 arch/loongarch/Kconfig                        |  4 ++
 arch/loongarch/dts/qemu-loongarch64.dts       |  9 +++
 board/emulation/qemu-loongarch/Kconfig        | 68 +++++++++++++++++++
 board/emulation/qemu-loongarch/MAINTAINERS    |  9 +++
 board/emulation/qemu-loongarch/Makefile       |  6 ++
 .../emulation/qemu-loongarch/qemu-loongarch.c | 67 ++++++++++++++++++
 .../qemu-loongarch/qemu-loongarch.env         |  5 ++
 configs/qemu-loongarch64_defconfig            | 36 ++++++++++
 doc/board/emulation/index.rst                 |  1 +
 doc/board/emulation/qemu-loongarch.rst        | 39 +++++++++++
 include/configs/qemu-loongarch.h              | 17 +++++
 11 files changed, 261 insertions(+)
 create mode 100644 arch/loongarch/dts/qemu-loongarch64.dts
 create mode 100644 board/emulation/qemu-loongarch/Kconfig
 create mode 100644 board/emulation/qemu-loongarch/MAINTAINERS
 create mode 100644 board/emulation/qemu-loongarch/Makefile
 create mode 100644 board/emulation/qemu-loongarch/qemu-loongarch.c
 create mode 100644 board/emulation/qemu-loongarch/qemu-loongarch.env
 create mode 100644 configs/qemu-loongarch64_defconfig
 create mode 100644 doc/board/emulation/qemu-loongarch.rst
 create mode 100644 include/configs/qemu-loongarch.h

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index c5ef82b583b1..ca7f0adb1496 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -7,9 +7,13 @@ config SYS_ARCH
 choice
 	prompt "Target select"
 
+config TARGET_QEMU_LOONGARCH_VIRT
+	bool "Support QEMU Virt Board"
+
 endchoice
 
 # board-specific options below
+source "board/emulation/qemu-loongarch/Kconfig"
 
 # platform-specific options below
 source "arch/loongarch/cpu/generic/Kconfig"
diff --git a/arch/loongarch/dts/qemu-loongarch64.dts b/arch/loongarch/dts/qemu-loongarch64.dts
new file mode 100644
index 000000000000..39d303798fcb
--- /dev/null
+++ b/arch/loongarch/dts/qemu-loongarch64.dts
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2024 Jiaxun Yang <[email protected]>
+ */
+
+/dts-v1/;
+
+/ {
+};
diff --git a/board/emulation/qemu-loongarch/Kconfig b/board/emulation/qemu-loongarch/Kconfig
new file mode 100644
index 000000000000..94f42091e0be
--- /dev/null
+++ b/board/emulation/qemu-loongarch/Kconfig
@@ -0,0 +1,68 @@
+if TARGET_QEMU_LOONGARCH_VIRT
+
+config SYS_BOARD
+	default "qemu-loongarch"
+
+config SYS_VENDOR
+	default "emulation"
+
+config SYS_CPU
+	default "generic"
+
+config SYS_CONFIG_NAME
+	default "qemu-loongarch"
+
+config TEXT_BASE
+	default 0x1c000000
+
+config BOARD_SPECIFIC_OPTIONS # dummy
+	def_bool y
+	select GENERIC_LOONGARCH
+	imply AHCI
+	imply PCI_INIT_R
+	imply CMD_PCI
+	imply CMD_POWEROFF
+	imply CMD_SCSI
+	imply CMD_PING
+	imply CMD_EXT2
+	imply CMD_EXT4
+	imply CMD_FAT
+	imply CMD_FS_GENERIC
+	imply DOS_PARTITION
+	imply ISO_PARTITION
+	imply EFI_PARTITION
+	imply SCSI_AHCI
+	imply AHCI_PCI
+	imply E1000
+	imply PCI
+	imply NVME_PCI
+	imply PCIE_ECAM_GENERIC
+	imply DM_RNG
+	imply DM_RTC
+	imply QFW
+	imply QFW_MMIO
+	imply SCSI
+	imply SYS_NS16550
+	imply SYSRESET
+	imply SYSRESET_CMD_POWEROFF
+	imply SYSRESET_SYSCON
+	imply VIRTIO_MMIO
+	imply VIRTIO_PCI
+	imply VIRTIO_NET
+	imply VIRTIO_BLK
+	imply MTD_NOR_FLASH
+	imply CFI_FLASH
+	imply OF_HAS_PRIOR_STAGE
+	imply VIDEO
+	imply VIDEO_BOCHS
+	imply SYS_WHITE_ON_BLACK
+	imply USB
+	imply USB_XHCI_HCD
+	imply USB_XHCI_PCI
+	imply USB_KEYBOARD
+	imply CMD_USB
+	imply UFS
+	imply UFS_PCI
+	imply BOARD_LATE_INIT
+
+endif
diff --git a/board/emulation/qemu-loongarch/MAINTAINERS b/board/emulation/qemu-loongarch/MAINTAINERS
new file mode 100644
index 000000000000..cd9636d6dc9b
--- /dev/null
+++ b/board/emulation/qemu-loongarch/MAINTAINERS
@@ -0,0 +1,9 @@
+QEMU LOONGARCH 'VIRT' BOARD
+M:	Jiaxun Yang <[email protected]>
+M:	Yao Zi <[email protected]>
+S:	Maintained
+F:	board/emulation/qemu-loongarch/
+F:	board/emulation/common/
+F:	include/configs/qemu-loongarch.h
+F:	configs/qemu-loongarch64_defconfig
+F:	doc/board/emulation/qemu-loongarch.rst
diff --git a/board/emulation/qemu-loongarch/Makefile b/board/emulation/qemu-loongarch/Makefile
new file mode 100644
index 000000000000..a928b90780e9
--- /dev/null
+++ b/board/emulation/qemu-loongarch/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2024 Jiaxun yang <[email protected]>
+#
+
+obj-y	+= qemu-loongarch.o
diff --git a/board/emulation/qemu-loongarch/qemu-loongarch.c b/board/emulation/qemu-loongarch/qemu-loongarch.c
new file mode 100644
index 000000000000..56e83fa17be0
--- /dev/null
+++ b/board/emulation/qemu-loongarch/qemu-loongarch.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2024 Jiaxun Yang <[email protected]>
+ */
+
+#include <dm.h>
+#include <dm/ofnode.h>
+#include <env.h>
+#include <fdtdec.h>
+#include <image.h>
+#include <linux/sizes.h>
+#include <lmb.h>
+#include <log.h>
+#include <spl.h>
+#include <init.h>
+#include <usb.h>
+#include <virtio_types.h>
+#include <virtio.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define VIRT_FDT_BASE 0x100000
+
+#if IS_ENABLED(CONFIG_MTD_NOR_FLASH)
+int is_flash_available(void)
+{
+	if (!ofnode_equal(ofnode_by_compatible(ofnode_null(), "cfi-flash"),
+			  ofnode_null()))
+		return 1;
+
+	return 0;
+}
+#endif
+
+phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
+{
+	/*
+	 * Limit RAM used by U-Boot to 4GiB to keep compatible with 32-bit-only
+	 * DMA peripherals, for example, emulated PCI cards.
+	 */
+	if (gd->ram_top > 0x10000000)
+		return 0x10000000;
+
+	return gd->ram_top;
+}
+
+int board_late_init(void)
+{
+	/* start usb so that usb keyboard can be used as input device */
+	if (CONFIG_IS_ENABLED(USB_KEYBOARD))
+		usb_init();
+
+	/*
+	 * Make sure virtio bus is enumerated so that peripherals
+	 * on the virtio bus can be discovered by their drivers
+	 */
+	virtio_init();
+
+	return 0;
+}
+
+int board_fdt_blob_setup(void **fdtp)
+{
+	/* QEMU stores the DTB to 0x100000 */
+	*fdtp = (void *)VIRT_FDT_BASE;
+	return 0;
+}
diff --git a/board/emulation/qemu-loongarch/qemu-loongarch.env b/board/emulation/qemu-loongarch/qemu-loongarch.env
new file mode 100644
index 000000000000..7655f26d8d6b
--- /dev/null
+++ b/board/emulation/qemu-loongarch/qemu-loongarch.env
@@ -0,0 +1,5 @@
+stdin=serial,usbkbd
+stdout=serial,vidconsole
+stderr=serial,vidconsole
+
+boot_targets=qfw usb scsi virtio nvme dhcp
diff --git a/configs/qemu-loongarch64_defconfig b/configs/qemu-loongarch64_defconfig
new file mode 100644
index 000000000000..d7f9c4338486
--- /dev/null
+++ b/configs/qemu-loongarch64_defconfig
@@ -0,0 +1,36 @@
+CONFIG_LOONGARCH=y
+CONFIG_SYS_MALLOC_LEN=0x800000
+CONFIG_SYS_MALLOC_F_LEN=0x4000
+CONFIG_NR_DRAM_BANKS=8
+CONFIG_ENV_SIZE=0x20000
+CONFIG_DEFAULT_DEVICE_TREE="qemu-loongarch64"
+CONFIG_DM_RESET=y
+CONFIG_SYS_LOAD_ADDR=0x02000000
+CONFIG_SHOW_REGS=y
+# CONFIG_OF_BOARD_FIXUP is not set
+CONFIG_SYS_PCI_64BIT=y
+CONFIG_FIT=y
+CONFIG_BOOTSTD_FULL=y
+CONFIG_SYS_BOOTM_LEN=0x4000000
+CONFIG_USE_BOOTARGS=y
+CONFIG_BOOTARGS_SUBST=y
+CONFIG_DISPLAY_CPUINFO=y
+CONFIG_DISPLAY_BOARDINFO=y
+# CONFIG_CMD_MII is not set
+CONFIG_CMD_2048=y
+CONFIG_CMD_RTC=y
+CONFIG_CMD_TIME=y
+CONFIG_CMD_SYSBOOT=y
+CONFIG_CMD_QFW=y
+CONFIG_PARTITION_TYPE_GUID=y
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_BLKMAP=y
+CONFIG_EFI_MEDIA=y
+CONFIG_DM_MMC=y
+CONFIG_DM_MTD=y
+CONFIG_FLASH_SHOW_PROGRESS=0
+CONFIG_SYS_MAX_FLASH_BANKS=2
+CONFIG_PCI_REGION_MULTI_ENTRY=y
+CONFIG_DM_REBOOT_MODE=y
+CONFIG_RESET_SYSCON=y
+CONFIG_HEXDUMP=y
diff --git a/doc/board/emulation/index.rst b/doc/board/emulation/index.rst
index 5d0dd83d8aca..a142cd3360ac 100644
--- a/doc/board/emulation/index.rst
+++ b/doc/board/emulation/index.rst
@@ -11,6 +11,7 @@ Emulation
    network
    video
    qemu-arm
+   qemu-loongarch
    qemu-mips
    qemu-ppce500
    qemu-riscv
diff --git a/doc/board/emulation/qemu-loongarch.rst b/doc/board/emulation/qemu-loongarch.rst
new file mode 100644
index 000000000000..0d97dc7df797
--- /dev/null
+++ b/doc/board/emulation/qemu-loongarch.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+.. Copyright (C) 2026 Yao Zi <[email protected]>
+
+QEMU LoongArch
+==============
+
+QEMU for LoongArch supports a special 'virt' machine designed for emulation
+and virtualization purpose. This document describes how to run U-Boot under it.
+Only 64-bit LoongArch is supported at this time.
+
+The 'virt' platform provides the following as the basic functionality:
+
+    - A freely configurable amount of CPU cores
+    - U-Boot loaded and executing in the emulated flash, mapped to 0x1c000000.
+    - A generated device tree blob placed at 0x100000.
+    - A freely configurable amount of RAM, described by the DTB, starting at
+      0x0. RAM above 512MiB is placed at 0x80000000.
+    - A NS16550A serial port, discoverable via the DTB.
+    - An in-core constant frequency timer.
+    - syscon-reboot and syscon-poweroff for powering off and rebooting the
+      system.
+    - A generic ECAM-based PCI host controller, discoverable via the DTB.
+
+Additionally, a number of optional peripherals can be added to the PCI bus.
+
+See :doc:`../../develop/devicetree/dt_qemu` for information on how to see the
+devicetree actually generated by QEMU.
+
+Building and Running
+--------------------
+
+Set the CROSS_COMPILE environment variable as usual, and run::
+
+    make qemu-loongarch64_defconfig
+    make
+
+The minimal QEMU command line to get U-Boot up and running is::
+
+    qemu-system-loongarch64 -M virt -nographic -bios u-boot.bin
diff --git a/include/configs/qemu-loongarch.h b/include/configs/qemu-loongarch.h
new file mode 100644
index 000000000000..7103dc1b02ef
--- /dev/null
+++ b/include/configs/qemu-loongarch.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2024 Jiaxun Yang <[email protected]>
+ */
+
+#ifndef __CONFIG_H
+#define __CONFIG_H
+
+/*
+ * LoongArch QEMU always places a part of the RAM at 0x0. These options are only
+ * intended to specify the initial stack pointer address, and can be replaced
+ * with CUSTOM_SYS_INIT_SP_ADDR when it's supported in the future.
+ */
+#define CFG_SYS_INIT_RAM_ADDR	0x0
+#define CFG_SYS_INIT_RAM_SIZE	0x80000
+
+#endif
-- 
2.55.0