[PATCH v3 0/6] m68k: Add support for QEMU virt machine

[PATCH v3 0/6] m68k: Add support for QEMU virt machine

[Kuan-Wei Chiu]

Add support for the QEMU 'virt' machine on the m68k architecture. The
QEMU virt machine models a generic system utilizing Goldfish virtual
peripherals and is capable of emulating various classic 68k CPUs.

Currently, U-Boot's m68k architecture support focuses on ColdFire
variants. Expand this to include the classic M680x0 architecture,
implementing the necessary exception vectors, startup code, and a
bootinfo parser compatible with the QEMU interface. A driver for the
Goldfish TTY is also added to enable serial console output.

The implementation has been verified on QEMU targeting the M68040 CPU,
confirming successful hardware initialization and boot to the U-Boot
command shell. Additionally, the CI configuration was verified locally
using gitlab-ci-local "qemu_m68k_virt test.py", resulting in
PASS qemu_m68k_virt test.py.
---
Changes in v3:
- Add Goldfish timer driver.
- Update Goldfish RTC driver to support non-DT probing.
- Enable Goldfish RTC and Timer support in board configuration.
- Add safety loop limit to bootinfo parsing in dram_init.
- Remove dummy timer functions from architecture code.
- Remove unnecessary type casts in Goldfish TTY driver.
- Remove TEST_PY_ID from CI job definitions.
- Update documentation to include new RTC support.

Changes in v2:
- Refactor Goldfish TTY driver to use priv data for the RX buffer and
  ensure single-byte reads.
- Rename arch/m68k/cpu/m68040 to arch/m68k/cpu/m680x0 to separate the
  architecture family from the specific CPU model.
- Introduce M680x0 Kconfig symbol and separate MAINTAINERS entries for
  the architecture and the board.
- Regenerate qemu-m68k_defconfig using make savedefconfig and add the
  board to the documentation index.
- Add a new patch to enable CI testing on GitLab and Azure Pipelines.
- Update SPDX identifiers to GPL-2.0-or-later.
- Sort headers alphabetically.
- Fix tabs vs spaces.

v2: https://lore.kernel.org/u-boot/20251226175400.1154417-1-visitorckw@gmail.com/
v1: https://lore.kernel.org/u-boot/20251218185252.957388-1-visitorckw@gmail.com/

Kuan-Wei Chiu (6):
  serial: Add Goldfish TTY driver
  timer: Add Goldfish timer driver
  rtc: goldfish: Support platform data for non-DT probing
  m68k: Add support for M68040 CPU
  board: Add QEMU m68k virt board support
  CI: Add test jobs for QEMU m68k virt machine

 .azure-pipelines.yml                  |   3 +
 .gitlab-ci.yml                        |   6 ++
 MAINTAINERS                           |  18 ++++
 arch/m68k/Kconfig                     |  24 ++++++
 arch/m68k/Makefile                    |   1 +
 arch/m68k/config.mk                   |  10 ++-
 arch/m68k/cpu/m680x0/Makefile         |   6 ++
 arch/m68k/cpu/m680x0/cpu.c            |  72 ++++++++++++++++
 arch/m68k/cpu/m680x0/start.S          |  73 ++++++++++++++++
 arch/m68k/cpu/m680x0/u-boot.lds       |  47 +++++++++++
 arch/m68k/include/asm/bootinfo.h      |  31 +++++++
 arch/m68k/lib/Makefile                |   9 +-
 board/emulation/qemu-m68k/Kconfig     |  12 +++
 board/emulation/qemu-m68k/MAINTAINERS |   8 ++
 board/emulation/qemu-m68k/Makefile    |   5 ++
 board/emulation/qemu-m68k/qemu-m68k.c | 115 ++++++++++++++++++++++++++
 configs/qemu-m68k_defconfig           |  16 ++++
 doc/board/emulation/index.rst         |   1 +
 doc/board/emulation/qemu-m68k.rst     |  39 +++++++++
 drivers/rtc/goldfish_rtc.c            |  10 ++-
 drivers/serial/Kconfig                |   8 ++
 drivers/serial/Makefile               |   1 +
 drivers/serial/serial_goldfish.c      | 102 +++++++++++++++++++++++
 drivers/timer/Kconfig                 |   8 ++
 drivers/timer/Makefile                |   1 +
 drivers/timer/goldfish_timer.c        |  60 ++++++++++++++
 include/configs/qemu-m68k.h           |  18 ++++
 include/goldfish_rtc.h                |  15 ++++
 include/goldfish_timer.h              |  13 +++
 include/goldfish_tty.h                |  18 ++++
 30 files changed, 740 insertions(+), 10 deletions(-)
 create mode 100644 arch/m68k/cpu/m680x0/Makefile
 create mode 100644 arch/m68k/cpu/m680x0/cpu.c
 create mode 100644 arch/m68k/cpu/m680x0/start.S
 create mode 100644 arch/m68k/cpu/m680x0/u-boot.lds
 create mode 100644 arch/m68k/include/asm/bootinfo.h
 create mode 100644 board/emulation/qemu-m68k/Kconfig
 create mode 100644 board/emulation/qemu-m68k/MAINTAINERS
 create mode 100644 board/emulation/qemu-m68k/Makefile
 create mode 100644 board/emulation/qemu-m68k/qemu-m68k.c
 create mode 100644 configs/qemu-m68k_defconfig
 create mode 100644 doc/board/emulation/qemu-m68k.rst
 create mode 100644 drivers/serial/serial_goldfish.c
 create mode 100644 drivers/timer/goldfish_timer.c
 create mode 100644 include/configs/qemu-m68k.h
 create mode 100644 include/goldfish_rtc.h
 create mode 100644 include/goldfish_timer.h
 create mode 100644 include/goldfish_tty.h

-- 
2.52.0.358.g0dd7633a29-goog

[PATCH v3 1/6] serial: Add Goldfish TTY driver

[Kuan-Wei Chiu]

Add support for the Google Goldfish TTY serial device. This virtual
device is commonly used in QEMU virtual machines (such as the m68k
virt machine) and Android emulators.

The driver implements basic console output and input polling using the
Goldfish MMIO interface.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Changes in v3:
- Remove unnecessary type casts for MMIO register access.

 MAINTAINERS                      |   6 ++
 drivers/serial/Kconfig           |   8 +++
 drivers/serial/Makefile          |   1 +
 drivers/serial/serial_goldfish.c | 102 +++++++++++++++++++++++++++++++
 include/goldfish_tty.h           |  18 ++++++
 5 files changed, 135 insertions(+)
 create mode 100644 drivers/serial/serial_goldfish.c
 create mode 100644 include/goldfish_tty.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 6ce0bbce13d..da4a6e4d518 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1259,6 +1259,12 @@ S:	Maintained
 F:	drivers/misc/gsc.c
 F:	include/gsc.h
 
+GOLDFISH SERIAL DRIVER
+M:	Kuan-Wei Chiu <visitorckw@gmail.com>
+S:	Maintained
+F:	drivers/serial/serial_goldfish.c
+F:	include/goldfish_tty.h
+
 I2C
 M:	Heiko Schocher <hs@nabladev.com>
 S:	Maintained
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 371d7aa5bba..b84cb9ec781 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1193,4 +1193,12 @@ config SYS_SDMR
 	depends on MPC8XX_CONS
 	default 0x0
 
+config SERIAL_GOLDFISH
+	bool "Goldfish TTY support"
+	depends on DM_SERIAL
+	help
+	  Select this to enable support for the Goldfish TTY serial port.
+	  This virtual device is commonly used by QEMU virtual machines
+	  (e.g. m68k virt) for console output.
+
 endif
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 8eaae62b0fc..fe8d23be512 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -63,3 +63,4 @@ obj-$(CONFIG_XTENSA_SEMIHOSTING_SERIAL) += serial_xtensa_semihosting.o
 obj-$(CONFIG_S5P4418_PL011_SERIAL) += serial_s5p4418_pl011.o
 
 obj-$(CONFIG_UART4_SERIAL) += serial_adi_uart4.o
+obj-$(CONFIG_SERIAL_GOLDFISH) += serial_goldfish.o
diff --git a/drivers/serial/serial_goldfish.c b/drivers/serial/serial_goldfish.c
new file mode 100644
index 00000000000..1d2977d809d
--- /dev/null
+++ b/drivers/serial/serial_goldfish.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ * Goldfish TTY driver for U-Boot
+ */
+
+#include <asm/io.h>
+#include <dm.h>
+#include <goldfish_tty.h>
+#include <linux/types.h>
+#include <serial.h>
+
+/* Goldfish TTY Register Offsets */
+#define GOLDFISH_TTY_PUT_CHAR       0x00
+#define GOLDFISH_TTY_BYTES_READY    0x04
+#define GOLDFISH_TTY_CMD            0x08
+#define GOLDFISH_TTY_DATA_PTR       0x10
+#define GOLDFISH_TTY_DATA_LEN       0x14
+#define GOLDFISH_TTY_DATA_PTR_HIGH  0x18
+#define GOLDFISH_TTY_VERSION        0x20
+
+/* Commands */
+#define CMD_WRITE_BUFFER   2
+#define CMD_READ_BUFFER    3
+
+struct goldfish_tty_priv {
+	void __iomem *base;
+	u8 rx_buf;
+};
+
+static int goldfish_serial_getc(struct udevice *dev)
+{
+	struct goldfish_tty_priv *priv = dev_get_priv(dev);
+	unsigned long paddr;
+	u32 count;
+
+	count = __raw_readl(priv->base + GOLDFISH_TTY_BYTES_READY);
+	if (count == 0)
+		return -EAGAIN;
+
+	paddr = virt_to_phys((void *)&priv->rx_buf);
+
+	__raw_writel(0, priv->base + GOLDFISH_TTY_DATA_PTR_HIGH);
+	__raw_writel(paddr, priv->base + GOLDFISH_TTY_DATA_PTR);
+	__raw_writel(1, priv->base + GOLDFISH_TTY_DATA_LEN);
+	__raw_writel(CMD_READ_BUFFER, priv->base + GOLDFISH_TTY_CMD);
+
+	return priv->rx_buf;
+}
+
+static int goldfish_serial_putc(struct udevice *dev, const char ch)
+{
+	struct goldfish_tty_priv *priv = dev_get_priv(dev);
+
+	__raw_writel(ch, priv->base + GOLDFISH_TTY_PUT_CHAR);
+
+	return 0;
+}
+
+static int goldfish_serial_pending(struct udevice *dev, bool input)
+{
+	struct goldfish_tty_priv *priv = dev_get_priv(dev);
+
+	if (input)
+		return __raw_readl(priv->base + GOLDFISH_TTY_BYTES_READY);
+
+	return 0;
+}
+
+static int goldfish_serial_probe(struct udevice *dev)
+{
+	struct goldfish_tty_priv *priv = dev_get_priv(dev);
+	struct goldfish_tty_plat *plat = dev_get_plat(dev);
+
+	if (!plat)
+		return -EINVAL;
+
+	priv->base = plat->base;
+
+	return 0;
+}
+
+static const struct dm_serial_ops goldfish_serial_ops = {
+	.putc = goldfish_serial_putc,
+	.pending = goldfish_serial_pending,
+	.getc = goldfish_serial_getc,
+};
+
+static const struct udevice_id goldfish_serial_ids[] = {
+	{ .compatible = "google,goldfish-tty" },
+	{ }
+};
+
+U_BOOT_DRIVER(serial_goldfish) = {
+	.name	= "serial_goldfish",
+	.id	= UCLASS_SERIAL,
+	.of_match = goldfish_serial_ids,
+	.probe	= goldfish_serial_probe,
+	.ops	= &goldfish_serial_ops,
+	.priv_auto = sizeof(struct goldfish_tty_priv),
+	.flags	= DM_FLAG_PRE_RELOC,
+};
diff --git a/include/goldfish_tty.h b/include/goldfish_tty.h
new file mode 100644
index 00000000000..8777da4942d
--- /dev/null
+++ b/include/goldfish_tty.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#ifndef _GOLDFISH_TTY_H_
+#define _GOLDFISH_TTY_H_
+
+#include <linux/types.h>
+
+/* Platform data for the Goldfish TTY driver
+ * Used to pass hardware base address from Board to Driver
+ */
+struct goldfish_tty_plat {
+	void __iomem *base;
+};
+
+#endif /* _GOLDFISH_TTY_H_ */
-- 
2.52.0.358.g0dd7633a29-goog

[PATCH v3 2/6] timer: Add Goldfish timer driver

[Kuan-Wei Chiu]

Add support for the Goldfish timer driver. This driver utilizes the
Goldfish RTC hardware to provide a nanosecond-resolution timer. This
virtual device is commonly found in QEMU virtual machines (such as the
m68k virt machine) and Android emulators.

The driver implements the standard U-Boot timer UCLASS interface,
exposing a 64-bit monotonically increasing counter with a 1GHz clock
rate derived from the RTC registers.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Changes in v3:
- New patch.

The link provided by Daniel [1] returned a 404 error.
Since the implementation is straightforward, I wrote this driver from
scratch.

[1]: https://github.com/fifteenhex/u-boot/blob/mc68000/drivers/rtc/goldfish_timer.c

 MAINTAINERS                    |  6 ++++
 drivers/timer/Kconfig          |  8 +++++
 drivers/timer/Makefile         |  1 +
 drivers/timer/goldfish_timer.c | 60 ++++++++++++++++++++++++++++++++++
 include/goldfish_timer.h       | 13 ++++++++
 5 files changed, 88 insertions(+)
 create mode 100644 drivers/timer/goldfish_timer.c
 create mode 100644 include/goldfish_timer.h

diff --git a/MAINTAINERS b/MAINTAINERS
index da4a6e4d518..fcc437a53ce 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1265,6 +1265,12 @@ S:	Maintained
 F:	drivers/serial/serial_goldfish.c
 F:	include/goldfish_tty.h
 
+GOLDFISH TIMER DRIVER
+M:	Kuan-Wei Chiu <visitorckw@gmail.com>
+S:	Maintained
+F:	drivers/timer/goldfish_timer.c
+F:	include/goldfish_timer.h
+
 I2C
 M:	Heiko Schocher <hs@nabladev.com>
 S:	Maintained
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index f9511503b02..a84a0dc0539 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -340,4 +340,12 @@ config STARFIVE_TIMER
 	  Select this to enable support for the timer found on
 	  Starfive SoC.
 
+config GOLDFISH_TIMER
+	bool "Goldfish Timer support"
+	depends on TIMER
+	help
+	  Select this to enable support for the Goldfish Timer.
+	  It uses the Goldfish RTC hardware to provide a nanosecond-resolution
+	  timer, commonly found in QEMU virt machines.
+
 endmenu
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index a72e411fb2f..d8b3f2b65d4 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -36,3 +36,4 @@ obj-$(CONFIG_MCHP_PIT64B_TIMER)	+= mchp-pit64b-timer.o
 obj-$(CONFIG_IMX_GPT_TIMER)	+= imx-gpt-timer.o
 obj-$(CONFIG_XILINX_TIMER)	+= xilinx-timer.o
 obj-$(CONFIG_STARFIVE_TIMER)	+= starfive-timer.o
+obj-$(CONFIG_GOLDFISH_TIMER)	+= goldfish_timer.o
diff --git a/drivers/timer/goldfish_timer.c b/drivers/timer/goldfish_timer.c
new file mode 100644
index 00000000000..8205ac77853
--- /dev/null
+++ b/drivers/timer/goldfish_timer.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ *
+ * Goldfish Timer driver
+ */
+
+#include <dm.h>
+#include <timer.h>
+#include <asm/io.h>
+#include <linux/errno.h>
+#include <goldfish_timer.h>
+
+/* Goldfish RTC registers used as Timer */
+#define TIMER_TIME_LOW	0x00
+#define TIMER_TIME_HIGH	0x04
+
+static u64 goldfish_timer_get_count(struct udevice *dev)
+{
+	struct goldfish_timer_plat *plat = dev_get_plat(dev);
+	u32 low, high;
+	u64 time;
+
+	/*
+	 * Goldfish RTC provides time in nanoseconds.
+	 * We read the high 32-bits and low 32-bits to construct the 64-bit value.
+	 */
+	low = readl(plat->base + TIMER_TIME_LOW);
+	high = readl(plat->base + TIMER_TIME_HIGH);
+
+	time = ((u64)high << 32) | low;
+
+	return time;
+}
+
+static int goldfish_timer_probe(struct udevice *dev)
+{
+	struct goldfish_timer_plat *plat = dev_get_plat(dev);
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (!plat || !plat->base)
+		return -EINVAL;
+
+	/* Goldfish RTC counts in nanoseconds, so the rate is 1GHz */
+	uc_priv->clock_rate = 1000000000;
+
+	return 0;
+}
+
+static const struct timer_ops goldfish_timer_ops = {
+	.get_count = goldfish_timer_get_count,
+};
+
+U_BOOT_DRIVER(goldfish_timer) = {
+	.name	= "goldfish_timer",
+	.id	= UCLASS_TIMER,
+	.ops	= &goldfish_timer_ops,
+	.probe	= goldfish_timer_probe,
+	.plat_auto = sizeof(struct goldfish_timer_plat),
+};
diff --git a/include/goldfish_timer.h b/include/goldfish_timer.h
new file mode 100644
index 00000000000..2ea28170759
--- /dev/null
+++ b/include/goldfish_timer.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#ifndef _GOLDFISH_TIMER_H_
+#define _GOLDFISH_TIMER_H_
+
+struct goldfish_timer_plat {
+	void __iomem *base;
+};
+
+#endif /* _GOLDFISH_TIMER_H_ */
-- 
2.52.0.358.g0dd7633a29-goog

[PATCH v3 3/6] rtc: goldfish: Support platform data for non-DT probing

[Kuan-Wei Chiu]

Currently, the Goldfish RTC driver exclusively relies on device tree
to retrieve the base address, failing immediately if dev_read_addr()
returns FDT_ADDR_T_NONE. This restriction prevents the driver from
being used on platforms that instantiate devices via U_BOOT_DRVINFO()
instead of device tree, such as the QEMU m68k virt machine.

Add support for platform data to address this limitation. Update the
probe function to fall back to retrieving the base address from
struct goldfish_rtc_plat if the device tree address is unavailable.
Introduce a new header file include/goldfish_rtc.h to define the
platform data structure.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Changes in v3:
- New patch.

It appears there is no specific maintainer listed for this driver?

 drivers/rtc/goldfish_rtc.c | 10 ++++++++--
 include/goldfish_rtc.h     | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 include/goldfish_rtc.h

diff --git a/drivers/rtc/goldfish_rtc.c b/drivers/rtc/goldfish_rtc.c
index e63a2766c76..900daabccb9 100644
--- a/drivers/rtc/goldfish_rtc.c
+++ b/drivers/rtc/goldfish_rtc.c
@@ -9,6 +9,7 @@
 
 #include <div64.h>
 #include <dm.h>
+#include <goldfish_rtc.h>
 #include <mapmem.h>
 #include <rtc.h>
 #include <linux/io.h>
@@ -77,11 +78,16 @@ static int goldfish_rtc_set(struct udevice *dev, const struct rtc_time *time)
 static int goldfish_rtc_probe(struct udevice *dev)
 {
 	struct goldfish_rtc *priv = dev_get_priv(dev);
+	struct goldfish_rtc_plat *plat;
 	fdt_addr_t addr;
 
 	addr = dev_read_addr(dev);
-	if (addr == FDT_ADDR_T_NONE)
-		return -EINVAL;
+	if (addr == FDT_ADDR_T_NONE) {
+		plat = dev_get_plat(dev);
+		if (!plat)
+			return -EINVAL;
+		addr = (fdt_addr_t)plat->base;
+	}
 	priv->base = map_sysmem(addr, 0x20);
 
 	return 0;
diff --git a/include/goldfish_rtc.h b/include/goldfish_rtc.h
new file mode 100644
index 00000000000..bb113a0bd79
--- /dev/null
+++ b/include/goldfish_rtc.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#ifndef _GOLDFISH_RTC_H_
+#define _GOLDFISH_RTC_H_
+
+#include <linux/types.h>
+
+struct goldfish_rtc_plat {
+	void __iomem *base;
+};
+
+#endif /* _GOLDFISH_RTC_H_ */
-- 
2.52.0.358.g0dd7633a29-goog

[PATCH v3 4/6] m68k: Add support for M68040 CPU

[Kuan-Wei Chiu]

Add support for the Motorola 68040 architecture. Currently, m68k
support in U-Boot is primarily focused on ColdFire variants. Introduce
the necessary infrastructure to support the classic M680x0 series,
specifically targeting the M68040 as emulated by QEMU.

The implementation includes exception vectors, early startup code, and
minimal CPU initialization and relocation stubs. It also defines the
standard m68k boot information structure used for passing hardware
information to the operating system. To ensure compatibility, ColdFire-
specific library objects such as cache and interrupt handling are
excluded from the build when M68040 is selected.

Additionally, apply a specific workaround during the early memory
reservation stage. Use a manual loop to clear global data instead of
the standard memset() function, as utilizing memset() at this point was
observed to cause a hang on the QEMU platform.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Changes in v3:
- Remove dummy timer functions.

 MAINTAINERS                      |  6 +++
 arch/m68k/Kconfig                | 16 +++++++
 arch/m68k/Makefile               |  1 +
 arch/m68k/config.mk              | 10 ++++-
 arch/m68k/cpu/m680x0/Makefile    |  6 +++
 arch/m68k/cpu/m680x0/cpu.c       | 72 +++++++++++++++++++++++++++++++
 arch/m68k/cpu/m680x0/start.S     | 73 ++++++++++++++++++++++++++++++++
 arch/m68k/cpu/m680x0/u-boot.lds  | 47 ++++++++++++++++++++
 arch/m68k/include/asm/bootinfo.h | 31 ++++++++++++++
 arch/m68k/lib/Makefile           |  9 ++--
 10 files changed, 263 insertions(+), 8 deletions(-)
 create mode 100644 arch/m68k/cpu/m680x0/Makefile
 create mode 100644 arch/m68k/cpu/m680x0/cpu.c
 create mode 100644 arch/m68k/cpu/m680x0/start.S
 create mode 100644 arch/m68k/cpu/m680x0/u-boot.lds
 create mode 100644 arch/m68k/include/asm/bootinfo.h

diff --git a/MAINTAINERS b/MAINTAINERS
index fcc437a53ce..bfb24fa7bd3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1312,6 +1312,12 @@ F:	lib/getopt.c
 F:	test/log/
 F:	test/py/tests/test_log.py
 
+M680X0 ARCHITECTURE
+M:	Kuan-Wei Chiu <visitorckw@gmail.com>
+S:	Maintained
+F:	arch/m68k/cpu/m680x0/
+F:	arch/m68k/include/asm/bootinfo.h
+
 MALI DISPLAY PROCESSORS
 M:	Liviu Dudau <liviu.dudau@foss.arm.com>
 S:	Supported
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 8ade6f7b9d1..de7c673c376 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -56,6 +56,9 @@ config MCF5441x
         select DM_SERIAL
 	bool
 
+config M680x0
+	bool
+
 # processor type
 config M5208
 	bool
@@ -110,6 +113,10 @@ config M54418
 	bool
 	select MCF5441x
 
+config M68040
+	bool
+	select M680x0
+
 # peripherals
 config CF_DSPI
 	bool
@@ -178,6 +185,15 @@ config TARGET_STMARK2
 
 endchoice
 
+config SYS_CPU
+	string
+	default "mcf52x2" if MCF52x2
+	default "mcf523x" if MCF523x
+	default "mcf530x" if MCF530x
+	default "mcf532x" if MCF532x
+	default "mcf5445x" if MCF5445x
+	default "m680x0" if M680x0
+
 source "board/BuS/eb_cpu5282/Kconfig"
 source "board/cobra5272/Kconfig"
 source "board/freescale/m5208evbe/Kconfig"
diff --git a/arch/m68k/Makefile b/arch/m68k/Makefile
index 4a7960bbeb4..bb57cf9ac63 100644
--- a/arch/m68k/Makefile
+++ b/arch/m68k/Makefile
@@ -17,6 +17,7 @@ cpuflags-$(CONFIG_M5307)	:= -mcpu=5307
 cpuflags-$(CONFIG_MCF5301x)	:= -mcpu=53015 -fPIC
 cpuflags-$(CONFIG_MCF532x)	:= -mcpu=5329 -fPIC
 cpuflags-$(CONFIG_MCF5441x)	:= -mcpu=54418 -fPIC
+cpuflags-$(CONFIG_M68040)	:= -mcpu=68040 -fno-pic
 
 PLATFORM_CPPFLAGS += $(cpuflags-y)
 
diff --git a/arch/m68k/config.mk b/arch/m68k/config.mk
index 643b7d1d35d..458953f9712 100644
--- a/arch/m68k/config.mk
+++ b/arch/m68k/config.mk
@@ -3,8 +3,14 @@
 # (C) Copyright 2000-2002
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-PLATFORM_CPPFLAGS += -D__M68K__ -fPIC
+PLATFORM_CPPFLAGS += -D__M68K__
+ifneq ($(CONFIG_M680x0),y)
+PLATFORM_CPPFLAGS += -fPIC
+endif
 KBUILD_LDFLAGS    += -n -pie
 PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
-PLATFORM_RELFLAGS += -ffixed-d7 -msep-data
+PLATFORM_RELFLAGS += -ffixed-d7
+ifneq ($(CONFIG_M680x0),y)
+PLATFORM_RELFLAGS += -msep-data
+endif
 LDFLAGS_FINAL     += --gc-sections -pie
diff --git a/arch/m68k/cpu/m680x0/Makefile b/arch/m68k/cpu/m680x0/Makefile
new file mode 100644
index 00000000000..f6e0c9a46c0
--- /dev/null
+++ b/arch/m68k/cpu/m680x0/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+
+extra-y += start.o
+obj-y += cpu.o
diff --git a/arch/m68k/cpu/m680x0/cpu.c b/arch/m68k/cpu/m680x0/cpu.c
new file mode 100644
index 00000000000..e2974560f4d
--- /dev/null
+++ b/arch/m68k/cpu/m680x0/cpu.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * CPU specific code for m68040
+ *
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#include <asm/global_data.h>
+#include <config.h>
+#include <cpu_func.h>
+#include <init.h>
+#include <linux/types.h>
+#include <stdio.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+void m68k_virt_init_reserve(ulong base)
+{
+	struct global_data *gd_ptr = (struct global_data *)base;
+	char *p = (char *)gd_ptr;
+	unsigned int i;
+
+	/* FIXME: usage of memset() here caused a hang on QEMU m68k virt. */
+	for (i = 0; i < sizeof(*gd_ptr); i++)
+		p[i] = 0;
+
+	gd = gd_ptr;
+
+	gd->malloc_base = base + sizeof(*gd_ptr);
+}
+
+int print_cpuinfo(void)
+{
+	puts("CPU:   M68040 (QEMU Virt)\n");
+	return 0;
+}
+
+int get_clocks(void)
+{
+	return 0;
+}
+
+int cpu_init_r(void)
+{
+	return 0;
+}
+
+/*
+ * Relocation Stub
+ * We skip actual relocation for this QEMU bring-up and jump directly
+ * to board_init_r.
+ */
+
+void relocate_code(ulong sp, struct global_data *new_gd, ulong relocaddr)
+{
+	board_init_r(new_gd, relocaddr);
+}
+
+/* Stubs for Standard Facilities (Cache, Interrupts) */
+
+int disable_interrupts(void) { return 0; }
+void enable_interrupts(void) { return; }
+int interrupt_init(void) { return 0; }
+
+void icache_enable(void) {}
+void icache_disable(void) {}
+int icache_status(void) { return 0; }
+void dcache_enable(void) {}
+void dcache_disable(void) {}
+int dcache_status(void) { return 0; }
+void flush_cache(unsigned long start, unsigned long size) {}
+void flush_dcache_range(unsigned long start, unsigned long stop) {}
diff --git a/arch/m68k/cpu/m680x0/start.S b/arch/m68k/cpu/m680x0/start.S
new file mode 100644
index 00000000000..0802ca1fca2
--- /dev/null
+++ b/arch/m68k/cpu/m680x0/start.S
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Startup code for m68040
+ *
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#include <asm-offsets.h>
+#include <config.h>
+#include <linux/linkage.h>
+
+.section .text
+
+/*
+ * Vector Table
+ * m68k uses the first 1KB for the exception vector table.
+ */
+.balign 4
+.global _vectors
+_vectors:
+	.long	CFG_SYS_INIT_SP_ADDR	/* 0x00: Initial SP */
+	.long	_start	/* 0x04: Initial PC (Reset) */
+	.long	_fault	/* 0x08: Bus Error */
+	.long	_fault	/* 0x0C: Address Error */
+	.long	_fault	/* 0x10: Illegal Instruction */
+	.long	_fault	/* 0x14: Zero Divide */
+	.long	_fault	/* 0x18: CHK */
+	.long	_fault	/* 0x1C: TRAPV */
+	.long	_fault	/* 0x20: Privilege */
+	.long	_fault	/* 0x24: Trace */
+	.long	_fault	/* 0x28: Line 1010 */
+	.long	_fault	/* 0x2C: Line 1111 */
+	.fill	0x400 - (.-_vectors), 1, 0
+
+/*
+ * Entry Point
+ */
+ENTRY(_start)
+	/* Disable Interrupts */
+	move.w	#0x2700, %sr
+
+	/* Setup initial stack pointer */
+	move.l	#CFG_SYS_INIT_SP_ADDR, %sp
+
+	/*
+	 * Allocate Global Data (GD)
+	 * board_init_f_alloc_reserve(top) returns the new top of stack in %d0
+	 */
+	move.l	%sp, -(%sp)
+	bsr.l	board_init_f_alloc_reserve
+	addq.l	#4, %sp
+
+	/* Update Stack Pointer and set GD register */
+	move.l	%d0, %sp
+	move.l	%d0, %d7	/* %d7 is the gd register */
+
+	/* Initialize Reserved Memory. */
+	move.l	%d0, -(%sp)
+	bsr.l	m68k_virt_init_reserve
+	addq.l	#4, %sp
+
+	/* Enter board_init_f(0) */
+	clr.l	-(%sp)
+	bsr.l	board_init_f
+	addq.l	#4, %sp
+
+	/* Should not return */
+hang:
+	bra.s	hang
+ENDPROC(_start)
+
+_fault:
+	bra.s	_fault
diff --git a/arch/m68k/cpu/m680x0/u-boot.lds b/arch/m68k/cpu/m680x0/u-boot.lds
new file mode 100644
index 00000000000..ae102c32833
--- /dev/null
+++ b/arch/m68k/cpu/m680x0/u-boot.lds
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Linker Script for m68040
+ *
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+OUTPUT_ARCH(m68k)
+ENTRY(_start)
+
+SECTIONS
+{
+	. = 0x00000000;
+	__text_start = .;
+
+	.text :
+	{
+		arch/m68k/cpu/m680x0/start.o (.text*)
+		*(.text*)
+	}
+
+	. = ALIGN(16);
+	.rodata : { *(.rodata*) }
+
+	. = ALIGN(16);
+	.data : { *(.data*) }
+
+	. = ALIGN(4);
+	.u_boot_list : {
+		KEEP(*(SORT(*u_boot_list*)));
+	}
+
+	. = ALIGN(4);
+	__image_copy_end = .;
+	__init_end = .;
+
+	. = ALIGN(16);
+	__bss_start = .;
+	.bss :
+	{
+		*(.bss*)
+		. = ALIGN(16);
+	}
+	__bss_end = .;
+
+	_end = .;
+}
diff --git a/arch/m68k/include/asm/bootinfo.h b/arch/m68k/include/asm/bootinfo.h
new file mode 100644
index 00000000000..3d2ec818257
--- /dev/null
+++ b/arch/m68k/include/asm/bootinfo.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ *
+ * Definitions for the m68k bootinfo interface.
+ */
+
+#ifndef _ASM_M68K_BOOTINFO_H
+#define _ASM_M68K_BOOTINFO_H
+
+#ifndef __ASSEMBLY__
+
+struct bi_record {
+	unsigned short tag;        /* tag ID */
+	unsigned short size;       /* size of record (in bytes) */
+	unsigned long data[0];     /* data */
+};
+
+#endif /* __ASSEMBLY__ */
+
+/* Bootinfo Tag IDs */
+#define BI_LAST            0x0000
+#define BI_MACHTYPE        0x0001
+#define BI_CPUTYPE         0x0002
+#define BI_FPUTYPE         0x0003
+#define BI_MMUTYPE         0x0004
+#define BI_MEMCHUNK        0x0005
+#define BI_RAMDISK         0x0006
+#define BI_COMMAND_LINE    0x0007
+
+#endif /* _ASM_M68K_BOOTINFO_H */
diff --git a/arch/m68k/lib/Makefile b/arch/m68k/lib/Makefile
index 6e1fd938f52..e62de51f260 100644
--- a/arch/m68k/lib/Makefile
+++ b/arch/m68k/lib/Makefile
@@ -7,10 +7,7 @@
 ## if the user asked for it
 lib-$(CONFIG_USE_PRIVATE_LIBGCC) += lshrdi3.o muldi3.o ashldi3.o ashrdi3.o
 
-obj-y	+= bdinfo.o
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
-obj-y	+= cache.o
-obj-y	+= interrupts.o
-obj-y	+= time.o
-obj-y	+= traps.o
-obj-y   += fec.o
+ifndef CONFIG_M680x0
+obj-y += cache.o interrupts.o time.o traps.o bdinfo.o fec.o
+endif
-- 
2.52.0.358.g0dd7633a29-goog

[PATCH v3 5/6] board: Add QEMU m68k virt board support

[Kuan-Wei Chiu]

Add support for the QEMU 'virt' machine on the m68k architecture. This
board emulates a generic machine based on the Motorola 68040 CPU
equipped with Goldfish virtual peripherals.

Introduce the necessary board configuration and initialization
infrastructure. The implementation includes logic to parse the QEMU
bootinfo interface, enabling dynamic detection of system RAM size to
adapt to the virtual machine's configuration.

Enable the Goldfish TTY driver for serial console output. Additionally,
enable Goldfish RTC and timer drivers to support real-time clock
functionality and nanosecond-resolution delays. Include comprehensive
documentation covering build instructions and usage examples.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Changes in v3:
- Enable Goldfish RTC and timer support.
- Add safety loop limit to dram_init bootinfo parsing.
- Use ALIGN() macro for address alignment.
- Update documentation.

 arch/m68k/Kconfig                     |   8 ++
 board/emulation/qemu-m68k/Kconfig     |  12 +++
 board/emulation/qemu-m68k/MAINTAINERS |   8 ++
 board/emulation/qemu-m68k/Makefile    |   5 ++
 board/emulation/qemu-m68k/qemu-m68k.c | 115 ++++++++++++++++++++++++++
 configs/qemu-m68k_defconfig           |  16 ++++
 doc/board/emulation/index.rst         |   1 +
 doc/board/emulation/qemu-m68k.rst     |  39 +++++++++
 include/configs/qemu-m68k.h           |  18 ++++
 9 files changed, 222 insertions(+)
 create mode 100644 board/emulation/qemu-m68k/Kconfig
 create mode 100644 board/emulation/qemu-m68k/MAINTAINERS
 create mode 100644 board/emulation/qemu-m68k/Makefile
 create mode 100644 board/emulation/qemu-m68k/qemu-m68k.c
 create mode 100644 configs/qemu-m68k_defconfig
 create mode 100644 doc/board/emulation/qemu-m68k.rst
 create mode 100644 include/configs/qemu-m68k.h

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index de7c673c376..605ae5ec20c 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -183,6 +183,13 @@ config TARGET_STMARK2
         select CF_DSPI
         select M54418
 
+config TARGET_QEMU_M68K
+    bool "Support QEMU m68k virt"
+    select M68040
+    help
+      This target supports the QEMU m68k virtual machine (-M virt).
+      It simulates a Motorola 68040 CPU with Goldfish peripherals.
+
 endchoice
 
 config SYS_CPU
@@ -208,6 +215,7 @@ source "board/freescale/m5329evb/Kconfig"
 source "board/freescale/m5373evb/Kconfig"
 source "board/sysam/amcore/Kconfig"
 source "board/sysam/stmark2/Kconfig"
+source "board/emulation/qemu-m68k/Kconfig"
 
 config M68K_QEMU
 	bool "Build with workarounds for incomplete QEMU emulation"
diff --git a/board/emulation/qemu-m68k/Kconfig b/board/emulation/qemu-m68k/Kconfig
new file mode 100644
index 00000000000..aae6dfe400f
--- /dev/null
+++ b/board/emulation/qemu-m68k/Kconfig
@@ -0,0 +1,12 @@
+if TARGET_QEMU_M68K
+
+config SYS_BOARD
+	default "qemu-m68k"
+
+config SYS_VENDOR
+	default "emulation"
+
+config SYS_CONFIG_NAME
+	default "qemu-m68k"
+
+endif
diff --git a/board/emulation/qemu-m68k/MAINTAINERS b/board/emulation/qemu-m68k/MAINTAINERS
new file mode 100644
index 00000000000..90414c58465
--- /dev/null
+++ b/board/emulation/qemu-m68k/MAINTAINERS
@@ -0,0 +1,8 @@
+QEMU M68K VIRT BOARD
+M:	Kuan-Wei Chiu <visitorckw@gmail.com>
+S:	Maintained
+F:	board/emulation/qemu-m68k/
+F:	board/emulation/common/
+F:	include/configs/qemu-m68k.h
+F:	configs/qemu-m68k_defconfig
+F:	doc/board/emulation/qemu-m68k.rst
diff --git a/board/emulation/qemu-m68k/Makefile b/board/emulation/qemu-m68k/Makefile
new file mode 100644
index 00000000000..5cb2886ff5a
--- /dev/null
+++ b/board/emulation/qemu-m68k/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+
+obj-y += qemu-m68k.o
diff --git a/board/emulation/qemu-m68k/qemu-m68k.c b/board/emulation/qemu-m68k/qemu-m68k.c
new file mode 100644
index 00000000000..3b911b95343
--- /dev/null
+++ b/board/emulation/qemu-m68k/qemu-m68k.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#include <asm-generic/sections.h>
+#include <asm/bootinfo.h>
+#include <asm/global_data.h>
+#include <asm/io.h>
+#include <config.h>
+#include <dm/platdata.h>
+#include <goldfish_rtc.h>
+#include <goldfish_timer.h>
+#include <goldfish_tty.h>
+#include <init.h>
+#include <linux/errno.h>
+#include <serial.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* QEMU Virt Machine Hardware Map */
+#define VIRT_GF_RTC_MMIO_BASE  0xff007000
+#define VIRT_GF_TTY_MMIO_BASE  0xff008000
+#define VIRT_CTRL_MMIO_BASE    0xff009000
+#define VIRT_CTRL_RESET        0x01
+
+/*
+ * Theoretical limit derivation:
+ * Max Bootinfo Size (Standard Page) = 4096 bytes
+ * Min Record Size (Tag + Size)      = 4 bytes
+ * Max Records = 4096 / 4 = 1024
+ */
+#define MAX_BOOTINFO_RECORDS  1024
+
+int board_early_init_f(void)
+{
+	return 0;
+}
+
+int checkboard(void)
+{
+	puts("Board: QEMU m68k virt\n");
+	return 0;
+}
+
+int dram_init(void)
+{
+	struct bi_record *record;
+	ulong addr;
+	int loops = 0;
+
+	/* Default: 16MB */
+	gd->ram_size = 0x01000000;
+
+	/* QEMU places bootinfo after _end, aligned to 2 bytes */
+	addr = (ulong)&_end;
+	addr = ALIGN(addr, 2);
+
+	record = (struct bi_record *)addr;
+
+	if (record->tag != BI_MACHTYPE)
+		return 0;
+
+	while (record->tag != BI_LAST) {
+		if (++loops > MAX_BOOTINFO_RECORDS)
+			panic("Bootinfo loop exceeded");
+		if (record->tag == BI_MEMCHUNK) {
+			gd->ram_size = record->data[1];
+			break;
+		}
+		record = (struct bi_record *)((ulong)record + record->size);
+	}
+
+	return 0;
+}
+
+void reset_cpu(unsigned long addr)
+{
+	writel(VIRT_CTRL_RESET, VIRT_CTRL_MMIO_BASE);
+	while (1)
+		;
+}
+
+int do_reset(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+{
+	reset_cpu(0);
+	return 0;
+}
+
+static const struct goldfish_rtc_plat rtc_plat = {
+	.base = (void __iomem *)VIRT_GF_RTC_MMIO_BASE,
+};
+
+U_BOOT_DRVINFO(goldfish_rtc) = {
+	.name = "rtc_goldfish",
+	.plat = &rtc_plat,
+};
+
+static const struct goldfish_timer_plat timer_plat = {
+	.base = (void __iomem *)VIRT_GF_RTC_MMIO_BASE,
+};
+
+U_BOOT_DRVINFO(goldfish_timer) = {
+	.name = "goldfish_timer",
+	.plat = &timer_plat,
+};
+
+static const struct goldfish_tty_plat serial_plat = {
+	.base = (void __iomem *)VIRT_GF_TTY_MMIO_BASE,
+};
+
+U_BOOT_DRVINFO(goldfish_serial) = {
+	.name = "serial_goldfish",
+	.plat = &serial_plat,
+};
diff --git a/configs/qemu-m68k_defconfig b/configs/qemu-m68k_defconfig
new file mode 100644
index 00000000000..f9294218429
--- /dev/null
+++ b/configs/qemu-m68k_defconfig
@@ -0,0 +1,16 @@
+CONFIG_M68K=y
+CONFIG_TEXT_BASE=0x00000000
+CONFIG_SYS_MALLOC_LEN=0x20000
+CONFIG_SYS_MALLOC_F_LEN=0x2000
+CONFIG_SYS_MONITOR_LEN=262144
+CONFIG_SYS_BOOTM_LEN=0x1000000
+CONFIG_SYS_LOAD_ADDR=0x00000000
+CONFIG_TARGET_QEMU_M68K=y
+# CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_DM_RTC=y
+CONFIG_RTC_GOLDFISH=y
+CONFIG_DM_SERIAL=y
+CONFIG_SERIAL_GOLDFISH=y
+CONFIG_TIMER=y
+CONFIG_GOLDFISH_TIMER=y
diff --git a/doc/board/emulation/index.rst b/doc/board/emulation/index.rst
index f8908166276..4f7c812d493 100644
--- a/doc/board/emulation/index.rst
+++ b/doc/board/emulation/index.rst
@@ -15,6 +15,7 @@ Emulation
    qemu-sbsa
    qemu-x86
    qemu-xtensa
+   qemu-m68k
 
 Also see
 
diff --git a/doc/board/emulation/qemu-m68k.rst b/doc/board/emulation/qemu-m68k.rst
new file mode 100644
index 00000000000..6c4de54cf6a
--- /dev/null
+++ b/doc/board/emulation/qemu-m68k.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+.. Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+
+QEMU m68k
+=========
+
+QEMU for m68k supports a special 'virt' machine designed for emulation and
+virtualization purposes. This document describes how to run U-Boot under it.
+
+The QEMU virt machine models a generic m68k virtual machine with Goldfish
+interfaces. It supports the Motorola 68040 CPU architecture.
+
+Building U-Boot
+---------------
+Set the CROSS_COMPILE environment variable to your m68k toolchain, and run:
+
+.. code-block:: bash
+
+    export CROSS_COMPILE=m68k-linux-gnu-
+    make qemu-m68k_defconfig
+    make
+
+Running U-Boot
+--------------
+The minimal QEMU command line to get U-Boot up and running is:
+
+.. code-block:: bash
+
+    qemu-system-m68k -M virt -cpu m68040 -nographic -kernel u-boot
+
+Note that the `-nographic` option is used to redirect the console to stdio,
+which connects to the emulated Goldfish TTY device.
+
+Hardware Support
+----------------
+The following QEMU virt peripherals are supported in U-Boot:
+
+* Goldfish TTY (Serial Console)
+* Goldfish RTC (Real Time Clock)
diff --git a/include/configs/qemu-m68k.h b/include/configs/qemu-m68k.h
new file mode 100644
index 00000000000..1d8aa92fe80
--- /dev/null
+++ b/include/configs/qemu-m68k.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
+ */
+
+#ifndef __QEMU_M68K_H
+#define __QEMU_M68K_H
+
+/* Memory Configuration */
+#define CFG_SYS_SDRAM_BASE       0x00000000
+
+/*
+ * Initial Stack Pointer:
+ * Place the stack at 4MB offset to avoid overwriting U-Boot code/data.
+ */
+#define CFG_SYS_INIT_SP_ADDR     (CFG_SYS_SDRAM_BASE + 0x400000)
+
+#endif /* __QEMU_M68K_H */
-- 
2.52.0.358.g0dd7633a29-goog

[PATCH v3 6/6] CI: Add test jobs for QEMU m68k virt machine

[Kuan-Wei Chiu]

Enable CI testing for the newly introduced QEMU m68k 'virt' board on
both GitLab CI and Azure Pipelines. This ensures the new M68040
architecture support is built and booted correctly in the emulated
environment.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Changes in v3:
- Remove TEST_PY_ID

 .azure-pipelines.yml | 3 +++
 .gitlab-ci.yml       | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/.azure-pipelines.yml b/.azure-pipelines.yml
index e4695f1c55b..f563878b021 100644
--- a/.azure-pipelines.yml
+++ b/.azure-pipelines.yml
@@ -518,6 +518,9 @@ stages:
           TEST_PY_ID: "--id qemu"
           TEST_PY_TEST_SPEC: "not sleep and not efi"
           OVERRIDE: "-a CONFIG_M68K_QEMU=y -a ~CONFIG_MCFTMR"
+        qemu_m68k_virt:
+          TEST_PY_BD: "qemu-m68k"
+          TEST_PY_TEST_SPEC: "not sleep"
         qemu_malta:
           TEST_PY_BD: "malta"
           TEST_PY_ID: "--id qemu"
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e7234e003ea..1fc4d1e656d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -408,6 +408,12 @@ qemu_m68k test.py:
     OVERRIDE: "-a CONFIG_M68K_QEMU=y -a ~CONFIG_MCFTMR"
   <<: *buildman_and_testpy_dfn
 
+qemu_m68k_virt test.py:
+  variables:
+    TEST_PY_BD: "qemu-m68k"
+    TEST_PY_TEST_SPEC: "not sleep"
+  <<: *buildman_and_testpy_dfn
+
 qemu_malta test.py:
   variables:
     TEST_PY_BD: "malta"
-- 
2.52.0.358.g0dd7633a29-goog

Re: [PATCH v3 6/6] CI: Add test jobs for QEMU m68k virt machine

[Tom Rini]

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On Tue, Dec 30, 2025 at 04:01:12PM +0000, Kuan-Wei Chiu wrote:

> Enable CI testing for the newly introduced QEMU m68k 'virt' board on
> both GitLab CI and Azure Pipelines. This ensures the new M68040
> architecture support is built and booted correctly in the emulated
> environment.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>

Reviewed-by: Tom Rini <trini@konsulko.com>

-- 
Tom

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Re: [PATCH v3 1/6] serial: Add Goldfish TTY driver

[Yao Zi]

On Tue, Dec 30, 2025 at 04:01:07PM +0000, Kuan-Wei Chiu wrote:
> Add support for the Google Goldfish TTY serial device. This virtual
> device is commonly used in QEMU virtual machines (such as the m68k
> virt machine) and Android emulators.
> 
> The driver implements basic console output and input polling using the
> Goldfish MMIO interface.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> ---
> Changes in v3:
> - Remove unnecessary type casts for MMIO register access.
> 
>  MAINTAINERS                      |   6 ++
>  drivers/serial/Kconfig           |   8 +++
>  drivers/serial/Makefile          |   1 +
>  drivers/serial/serial_goldfish.c | 102 +++++++++++++++++++++++++++++++
>  include/goldfish_tty.h           |  18 ++++++
>  5 files changed, 135 insertions(+)
>  create mode 100644 drivers/serial/serial_goldfish.c
>  create mode 100644 include/goldfish_tty.h

This version looks good to me,

Reviewed-by: Yao Zi <me@ziyao.cc>

Re: [PATCH v3 2/6] timer: Add Goldfish timer driver

[Daniel Palmer]

Hi Kuan-Wei,

On Wed, 31 Dec 2025 at 01:01, Kuan-Wei Chiu <visitorckw@gmail.com> wrote:
>
> Add support for the Goldfish timer driver. This driver utilizes the
> Goldfish RTC hardware to provide a nanosecond-resolution timer. This
> virtual device is commonly found in QEMU virtual machines (such as the
> m68k virt machine) and Android emulators.
>
> The driver implements the standard U-Boot timer UCLASS interface,
> exposing a 64-bit monotonically increasing counter with a 1GHz clock
> rate derived from the RTC registers.
>
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>

>The link provided by Daniel [1] returned a 404 error.
>Since the implementation is straightforward, I wrote this driver from
>scratch.
>[1]: https://github.com/fifteenhex/u-boot/blob/mc68000/drivers/rtc/goldfish_timer.c

Oops, I moved it and force pushed. Sorry about that.

Works as expected.

Tested-by: Daniel Palmer <daniel@0x0f.com>

Re: [PATCH v3 1/6] serial: Add Goldfish TTY driver

[Daniel Palmer]

Hi Kuan-Wei,

On Wed, 31 Dec 2025 at 01:01, Kuan-Wei Chiu <visitorckw@gmail.com> wrote:
>
> Add support for the Google Goldfish TTY serial device. This virtual
> device is commonly used in QEMU virtual machines (such as the m68k
> virt machine) and Android emulators.
>
> The driver implements basic console output and input polling using the
> Goldfish MMIO interface.
>
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>

Tested that this works as expected for the console.

Tested-by: Daniel Palmer <daniel@0x0f.com>

Re: [PATCH v3 5/6] board: Add QEMU m68k virt board support

[Daniel Palmer]

Hi Kuan-Wei,

On Wed, 31 Dec 2025 at 01:01, Kuan-Wei Chiu <visitorckw@gmail.com> wrote:
>
> Add support for the QEMU 'virt' machine on the m68k architecture. This
> board emulates a generic machine based on the Motorola 68040 CPU
> equipped with Goldfish virtual peripherals.
>
> Introduce the necessary board configuration and initialization
> infrastructure. The implementation includes logic to parse the QEMU
> bootinfo interface, enabling dynamic detection of system RAM size to
> adapt to the virtual machine's configuration.
>
> Enable the Goldfish TTY driver for serial console output. Additionally,
> enable Goldfish RTC and timer drivers to support real-time clock
> functionality and nanosecond-resolution delays. Include comprehensive
> documentation covering build instructions and usage examples.
>
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>

I have roughly tested this in QEMU and everything seems to work as expected.

Tested-by: Daniel Palmer <daniel@0x0f.com>

If/When this gets merged it'd be nice to get the virtio mmio part
integrated next so we can access disk/network.
I think virtio mmio has endian issues in QEMU or u-boot as I had to
add code to swap everything to make it work in my version of this. :D

Thanks,

Daniel

Re: [PATCH v3 2/6] timer: Add Goldfish timer driver

[Yao Zi]

On Tue, Dec 30, 2025 at 04:01:08PM +0000, Kuan-Wei Chiu wrote:
> Add support for the Goldfish timer driver. This driver utilizes the
> Goldfish RTC hardware to provide a nanosecond-resolution timer. This
> virtual device is commonly found in QEMU virtual machines (such as the
> m68k virt machine) and Android emulators.
> 
> The driver implements the standard U-Boot timer UCLASS interface,
> exposing a 64-bit monotonically increasing counter with a 1GHz clock
> rate derived from the RTC registers.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> ---
> Changes in v3:
> - New patch.
> 
> The link provided by Daniel [1] returned a 404 error.
> Since the implementation is straightforward, I wrote this driver from
> scratch.
> 
> [1]: https://github.com/fifteenhex/u-boot/blob/mc68000/drivers/rtc/goldfish_timer.c

...

> diff --git a/drivers/timer/goldfish_timer.c b/drivers/timer/goldfish_timer.c
> new file mode 100644
> index 00000000000..8205ac77853
> --- /dev/null
> +++ b/drivers/timer/goldfish_timer.c
> @@ -0,0 +1,60 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
> + *
> + * Goldfish Timer driver
> + */
> +
> +#include <dm.h>
> +#include <timer.h>
> +#include <asm/io.h>
> +#include <linux/errno.h>
> +#include <goldfish_timer.h>

Sort the headers?

> +/* Goldfish RTC registers used as Timer */
> +#define TIMER_TIME_LOW	0x00
> +#define TIMER_TIME_HIGH	0x04
> +
> +static u64 goldfish_timer_get_count(struct udevice *dev)
> +{
> +	struct goldfish_timer_plat *plat = dev_get_plat(dev);
> +	u32 low, high;
> +	u64 time;
> +
> +	/*
> +	 * Goldfish RTC provides time in nanoseconds.
> +	 * We read the high 32-bits and low 32-bits to construct the 64-bit value.
> +	 */
> +	low = readl(plat->base + TIMER_TIME_LOW);
> +	high = readl(plat->base + TIMER_TIME_HIGH);

It may be worth a comment to point out that the value of TIMER_TIME_HIGH
only updates when TIMER_TIME_LOW is read, so it's impossible to read out
teared values (higher half has been updated after lower half is read).

> +	time = ((u64)high << 32) | low;
> +
> +	return time;
> +}

With the header sorted,

Reviewed-by: Yao Zi <me@ziyao.cc>

Regards,
Yao Zi

Re: [PATCH v3 3/6] rtc: goldfish: Support platform data for non-DT probing

[Heinrich Schuchardt]

On 12/30/25 17:01, Kuan-Wei Chiu wrote:
> Currently, the Goldfish RTC driver exclusively relies on device tree
> to retrieve the base address, failing immediately if dev_read_addr()
> returns FDT_ADDR_T_NONE. This restriction prevents the driver from
> being used on platforms that instantiate devices via U_BOOT_DRVINFO()
> instead of device tree, such as the QEMU m68k virt machine.
> 
> Add support for platform data to address this limitation. Update the
> probe function to fall back to retrieving the base address from
> struct goldfish_rtc_plat if the device tree address is unavailable.
> Introduce a new header file include/goldfish_rtc.h to define the
> platform data structure.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> ---
> Changes in v3:
> - New patch.
> 
> It appears there is no specific maintainer listed for this driver?
> 
>   drivers/rtc/goldfish_rtc.c | 10 ++++++++--
>   include/goldfish_rtc.h     | 15 +++++++++++++++
>   2 files changed, 23 insertions(+), 2 deletions(-)
>   create mode 100644 include/goldfish_rtc.h
> 
> diff --git a/drivers/rtc/goldfish_rtc.c b/drivers/rtc/goldfish_rtc.c
> index e63a2766c76..900daabccb9 100644
> --- a/drivers/rtc/goldfish_rtc.c
> +++ b/drivers/rtc/goldfish_rtc.c
> @@ -9,6 +9,7 @@
>   
>   #include <div64.h>
>   #include <dm.h>
> +#include <goldfish_rtc.h>
>   #include <mapmem.h>
>   #include <rtc.h>
>   #include <linux/io.h>
> @@ -77,11 +78,16 @@ static int goldfish_rtc_set(struct udevice *dev, const struct rtc_time *time)
>   static int goldfish_rtc_probe(struct udevice *dev)
>   {
>   	struct goldfish_rtc *priv = dev_get_priv(dev);
> +	struct goldfish_rtc_plat *plat;
>   	fdt_addr_t addr;
>   
>   	addr = dev_read_addr(dev);
> -	if (addr == FDT_ADDR_T_NONE)
> -		return -EINVAL;
> +	if (addr == FDT_ADDR_T_NONE) {
> +		plat = dev_get_plat(dev);
> +		if (!plat)
> +			return -EINVAL;
> +		addr = (fdt_addr_t)plat->base;

addr is not a pointer, it is an address in the sandbox virtual memory 
address space. This is why map_sysmem() is used below.

The suggested code fails to build on sandbox_defconfig with the driver 
enabled:

drivers/rtc/goldfish_rtc.c: In function ‘goldfish_rtc_probe’:
drivers/rtc/goldfish_rtc.c:89:24: warning: cast from pointer to integer 
of different size [-Wpointer-to-int-cast]
    89 |                 addr = (fdt_addr_t)plat->base;
       |

Please, use

	priv->base = plat->base;

If plat->base is NULL, please, throw -EINVAL.

Best regards

Heinrich

> +	}
>   	priv->base = map_sysmem(addr, 0x20);
>   
>   	return 0;
> diff --git a/include/goldfish_rtc.h b/include/goldfish_rtc.h
> new file mode 100644
> index 00000000000..bb113a0bd79
> --- /dev/null
> +++ b/include/goldfish_rtc.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
> + */
> +
> +#ifndef _GOLDFISH_RTC_H_
> +#define _GOLDFISH_RTC_H_
> +
> +#include <linux/types.h>
> +
> +struct goldfish_rtc_plat {
> +	void __iomem *base;
> +};
> +
> +#endif /* _GOLDFISH_RTC_H_ */

Re: [PATCH v3 1/6] serial: Add Goldfish TTY driver

[Heinrich Schuchardt]

On 12/30/25 17:01, Kuan-Wei Chiu wrote:
> Add support for the Google Goldfish TTY serial device. This virtual
> device is commonly used in QEMU virtual machines (such as the m68k
> virt machine) and Android emulators.
> 
> The driver implements basic console output and input polling using the
> Goldfish MMIO interface.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> ---
> Changes in v3:
> - Remove unnecessary type casts for MMIO register access.
> 
>   MAINTAINERS                      |   6 ++
>   drivers/serial/Kconfig           |   8 +++
>   drivers/serial/Makefile          |   1 +
>   drivers/serial/serial_goldfish.c | 102 +++++++++++++++++++++++++++++++
>   include/goldfish_tty.h           |  18 ++++++
>   5 files changed, 135 insertions(+)
>   create mode 100644 drivers/serial/serial_goldfish.c
>   create mode 100644 include/goldfish_tty.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6ce0bbce13d..da4a6e4d518 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1259,6 +1259,12 @@ S:	Maintained
>   F:	drivers/misc/gsc.c
>   F:	include/gsc.h
>   
> +GOLDFISH SERIAL DRIVER
> +M:	Kuan-Wei Chiu <visitorckw@gmail.com>
> +S:	Maintained
> +F:	drivers/serial/serial_goldfish.c
> +F:	include/goldfish_tty.h
> +
>   I2C
>   M:	Heiko Schocher <hs@nabladev.com>
>   S:	Maintained
> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> index 371d7aa5bba..b84cb9ec781 100644
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -1193,4 +1193,12 @@ config SYS_SDMR
>   	depends on MPC8XX_CONS
>   	default 0x0
>   
> +config SERIAL_GOLDFISH
> +	bool "Goldfish TTY support"
> +	depends on DM_SERIAL
> +	help
> +	  Select this to enable support for the Goldfish TTY serial port.
> +	  This virtual device is commonly used by QEMU virtual machines
> +	  (e.g. m68k virt) for console output.
> +
>   endif
> diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> index 8eaae62b0fc..fe8d23be512 100644
> --- a/drivers/serial/Makefile
> +++ b/drivers/serial/Makefile
> @@ -63,3 +63,4 @@ obj-$(CONFIG_XTENSA_SEMIHOSTING_SERIAL) += serial_xtensa_semihosting.o
>   obj-$(CONFIG_S5P4418_PL011_SERIAL) += serial_s5p4418_pl011.o
>   
>   obj-$(CONFIG_UART4_SERIAL) += serial_adi_uart4.o
> +obj-$(CONFIG_SERIAL_GOLDFISH) += serial_goldfish.o
> diff --git a/drivers/serial/serial_goldfish.c b/drivers/serial/serial_goldfish.c
> new file mode 100644
> index 00000000000..1d2977d809d
> --- /dev/null
> +++ b/drivers/serial/serial_goldfish.c
> @@ -0,0 +1,102 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
> + * Goldfish TTY driver for U-Boot
> + */
> +
> +#include <asm/io.h>
> +#include <dm.h>
> +#include <goldfish_tty.h>
> +#include <linux/types.h>
> +#include <serial.h>
> +
> +/* Goldfish TTY Register Offsets */
> +#define GOLDFISH_TTY_PUT_CHAR       0x00
> +#define GOLDFISH_TTY_BYTES_READY    0x04
> +#define GOLDFISH_TTY_CMD            0x08
> +#define GOLDFISH_TTY_DATA_PTR       0x10
> +#define GOLDFISH_TTY_DATA_LEN       0x14
> +#define GOLDFISH_TTY_DATA_PTR_HIGH  0x18
> +#define GOLDFISH_TTY_VERSION        0x20
> +
> +/* Commands */
> +#define CMD_WRITE_BUFFER   2
> +#define CMD_READ_BUFFER    3
> +
> +struct goldfish_tty_priv {
> +	void __iomem *base;
> +	u8 rx_buf;
> +};
> +
> +static int goldfish_serial_getc(struct udevice *dev)
> +{
> +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> +	unsigned long paddr;
> +	u32 count;
> +
> +	count = __raw_readl(priv->base + GOLDFISH_TTY_BYTES_READY);
> +	if (count == 0)
> +		return -EAGAIN;
> +
> +	paddr = virt_to_phys((void *)&priv->rx_buf);
> +
> +	__raw_writel(0, priv->base + GOLDFISH_TTY_DATA_PTR_HIGH);
> +	__raw_writel(paddr, priv->base + GOLDFISH_TTY_DATA_PTR);
> +	__raw_writel(1, priv->base + GOLDFISH_TTY_DATA_LEN);
> +	__raw_writel(CMD_READ_BUFFER, priv->base + GOLDFISH_TTY_CMD);
> +
> +	return priv->rx_buf;
> +}
> +
> +static int goldfish_serial_putc(struct udevice *dev, const char ch)
> +{
> +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> +
> +	__raw_writel(ch, priv->base + GOLDFISH_TTY_PUT_CHAR);
> +
> +	return 0;
> +}
> +
> +static int goldfish_serial_pending(struct udevice *dev, bool input)
> +{
> +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> +
> +	if (input)
> +		return __raw_readl(priv->base + GOLDFISH_TTY_BYTES_READY);
> +
> +	return 0;
> +}
> +
> +static int goldfish_serial_probe(struct udevice *dev)
> +{
> +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> +	struct goldfish_tty_plat *plat = dev_get_plat(dev);
> +
> +	if (!plat)
> +		return -EINVAL;
> +
> +	priv->base = plat->base;

The Linux binding documentation in 
Documentation/devicetree/bindings/goldfish/tty.txt has this example:

         goldfish_tty@1f004000 {
                 compatible = "google,goldfish-tty";
                 reg = <0x1f004000 0x1000>;
                 interrupts = <0xc>;
         };

The driver should take the reg value as address and use plat->base only 
as fallback for devices that don't provide a proper device-tree.

We already do this for the RTC driver. Please, apply the same logic to 
all Goldfish drivers.

Best regards

Heinrich


> +
> +	return 0;
> +}
> +
> +static const struct dm_serial_ops goldfish_serial_ops = {
> +	.putc = goldfish_serial_putc,
> +	.pending = goldfish_serial_pending,
> +	.getc = goldfish_serial_getc,
> +};
> +
> +static const struct udevice_id goldfish_serial_ids[] = {
> +	{ .compatible = "google,goldfish-tty" },
> +	{ }
> +};
> +
> +U_BOOT_DRIVER(serial_goldfish) = {
> +	.name	= "serial_goldfish",
> +	.id	= UCLASS_SERIAL,
> +	.of_match = goldfish_serial_ids,
> +	.probe	= goldfish_serial_probe,
> +	.ops	= &goldfish_serial_ops,
> +	.priv_auto = sizeof(struct goldfish_tty_priv),
> +	.flags	= DM_FLAG_PRE_RELOC,
> +};
> diff --git a/include/goldfish_tty.h b/include/goldfish_tty.h
> new file mode 100644
> index 00000000000..8777da4942d
> --- /dev/null
> +++ b/include/goldfish_tty.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
> + */
> +
> +#ifndef _GOLDFISH_TTY_H_
> +#define _GOLDFISH_TTY_H_
> +
> +#include <linux/types.h>
> +
> +/* Platform data for the Goldfish TTY driver
> + * Used to pass hardware base address from Board to Driver
> + */
> +struct goldfish_tty_plat {
> +	void __iomem *base;
> +};
> +
> +#endif /* _GOLDFISH_TTY_H_ */

Re: [PATCH v3 2/6] timer: Add Goldfish timer driver

[Kuan-Wei Chiu]

Hi Yao,

On Wed, Dec 31, 2025 at 06:27:49AM +0000, Yao Zi wrote:
> On Tue, Dec 30, 2025 at 04:01:08PM +0000, Kuan-Wei Chiu wrote:
> > Add support for the Goldfish timer driver. This driver utilizes the
> > Goldfish RTC hardware to provide a nanosecond-resolution timer. This
> > virtual device is commonly found in QEMU virtual machines (such as the
> > m68k virt machine) and Android emulators.
> > 
> > The driver implements the standard U-Boot timer UCLASS interface,
> > exposing a 64-bit monotonically increasing counter with a 1GHz clock
> > rate derived from the RTC registers.
> > 
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > ---
> > Changes in v3:
> > - New patch.
> > 
> > The link provided by Daniel [1] returned a 404 error.
> > Since the implementation is straightforward, I wrote this driver from
> > scratch.
> > 
> > [1]: https://github.com/fifteenhex/u-boot/blob/mc68000/drivers/rtc/goldfish_timer.c
> 
> ...
> 
> > diff --git a/drivers/timer/goldfish_timer.c b/drivers/timer/goldfish_timer.c
> > new file mode 100644
> > index 00000000000..8205ac77853
> > --- /dev/null
> > +++ b/drivers/timer/goldfish_timer.c
> > @@ -0,0 +1,60 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
> > + *
> > + * Goldfish Timer driver
> > + */
> > +
> > +#include <dm.h>
> > +#include <timer.h>
> > +#include <asm/io.h>
> > +#include <linux/errno.h>
> > +#include <goldfish_timer.h>
> 
> Sort the headers?

My apologies, I should have remembered that.
I will sort the headers in the next version.

> 
> > +/* Goldfish RTC registers used as Timer */
> > +#define TIMER_TIME_LOW	0x00
> > +#define TIMER_TIME_HIGH	0x04
> > +
> > +static u64 goldfish_timer_get_count(struct udevice *dev)
> > +{
> > +	struct goldfish_timer_plat *plat = dev_get_plat(dev);
> > +	u32 low, high;
> > +	u64 time;
> > +
> > +	/*
> > +	 * Goldfish RTC provides time in nanoseconds.
> > +	 * We read the high 32-bits and low 32-bits to construct the 64-bit value.
> > +	 */
> > +	low = readl(plat->base + TIMER_TIME_LOW);
> > +	high = readl(plat->base + TIMER_TIME_HIGH);
> 
> It may be worth a comment to point out that the value of TIMER_TIME_HIGH
> only updates when TIMER_TIME_LOW is read, so it's impossible to read out
> teared values (higher half has been updated after lower half is read).

Agreed.
I will add a comment explaining this.

> 
> > +	time = ((u64)high << 32) | low;
> > +
> > +	return time;
> > +}
> 
> With the header sorted,
> 
> Reviewed-by: Yao Zi <me@ziyao.cc>

Thanks for the review!

Regards,
Kuan-Wei

Re: [PATCH v3 1/6] serial: Add Goldfish TTY driver

[Kuan-Wei Chiu]

Hi Heinrich,

On Wed, Dec 31, 2025 at 01:25:10PM +0100, Heinrich Schuchardt wrote:
> On 12/30/25 17:01, Kuan-Wei Chiu wrote:
> > Add support for the Google Goldfish TTY serial device. This virtual
> > device is commonly used in QEMU virtual machines (such as the m68k
> > virt machine) and Android emulators.
> > 
> > The driver implements basic console output and input polling using the
> > Goldfish MMIO interface.
> > 
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > ---
> > Changes in v3:
> > - Remove unnecessary type casts for MMIO register access.
> > 
> >   MAINTAINERS                      |   6 ++
> >   drivers/serial/Kconfig           |   8 +++
> >   drivers/serial/Makefile          |   1 +
> >   drivers/serial/serial_goldfish.c | 102 +++++++++++++++++++++++++++++++
> >   include/goldfish_tty.h           |  18 ++++++
> >   5 files changed, 135 insertions(+)
> >   create mode 100644 drivers/serial/serial_goldfish.c
> >   create mode 100644 include/goldfish_tty.h
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 6ce0bbce13d..da4a6e4d518 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -1259,6 +1259,12 @@ S:	Maintained
> >   F:	drivers/misc/gsc.c
> >   F:	include/gsc.h
> > +GOLDFISH SERIAL DRIVER
> > +M:	Kuan-Wei Chiu <visitorckw@gmail.com>
> > +S:	Maintained
> > +F:	drivers/serial/serial_goldfish.c
> > +F:	include/goldfish_tty.h
> > +
> >   I2C
> >   M:	Heiko Schocher <hs@nabladev.com>
> >   S:	Maintained
> > diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> > index 371d7aa5bba..b84cb9ec781 100644
> > --- a/drivers/serial/Kconfig
> > +++ b/drivers/serial/Kconfig
> > @@ -1193,4 +1193,12 @@ config SYS_SDMR
> >   	depends on MPC8XX_CONS
> >   	default 0x0
> > +config SERIAL_GOLDFISH
> > +	bool "Goldfish TTY support"
> > +	depends on DM_SERIAL
> > +	help
> > +	  Select this to enable support for the Goldfish TTY serial port.
> > +	  This virtual device is commonly used by QEMU virtual machines
> > +	  (e.g. m68k virt) for console output.
> > +
> >   endif
> > diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> > index 8eaae62b0fc..fe8d23be512 100644
> > --- a/drivers/serial/Makefile
> > +++ b/drivers/serial/Makefile
> > @@ -63,3 +63,4 @@ obj-$(CONFIG_XTENSA_SEMIHOSTING_SERIAL) += serial_xtensa_semihosting.o
> >   obj-$(CONFIG_S5P4418_PL011_SERIAL) += serial_s5p4418_pl011.o
> >   obj-$(CONFIG_UART4_SERIAL) += serial_adi_uart4.o
> > +obj-$(CONFIG_SERIAL_GOLDFISH) += serial_goldfish.o
> > diff --git a/drivers/serial/serial_goldfish.c b/drivers/serial/serial_goldfish.c
> > new file mode 100644
> > index 00000000000..1d2977d809d
> > --- /dev/null
> > +++ b/drivers/serial/serial_goldfish.c
> > @@ -0,0 +1,102 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Copyright (C) 2025, Kuan-Wei Chiu <visitorckw@gmail.com>
> > + * Goldfish TTY driver for U-Boot
> > + */
> > +
> > +#include <asm/io.h>
> > +#include <dm.h>
> > +#include <goldfish_tty.h>
> > +#include <linux/types.h>
> > +#include <serial.h>
> > +
> > +/* Goldfish TTY Register Offsets */
> > +#define GOLDFISH_TTY_PUT_CHAR       0x00
> > +#define GOLDFISH_TTY_BYTES_READY    0x04
> > +#define GOLDFISH_TTY_CMD            0x08
> > +#define GOLDFISH_TTY_DATA_PTR       0x10
> > +#define GOLDFISH_TTY_DATA_LEN       0x14
> > +#define GOLDFISH_TTY_DATA_PTR_HIGH  0x18
> > +#define GOLDFISH_TTY_VERSION        0x20
> > +
> > +/* Commands */
> > +#define CMD_WRITE_BUFFER   2
> > +#define CMD_READ_BUFFER    3
> > +
> > +struct goldfish_tty_priv {
> > +	void __iomem *base;
> > +	u8 rx_buf;
> > +};
> > +
> > +static int goldfish_serial_getc(struct udevice *dev)
> > +{
> > +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> > +	unsigned long paddr;
> > +	u32 count;
> > +
> > +	count = __raw_readl(priv->base + GOLDFISH_TTY_BYTES_READY);
> > +	if (count == 0)
> > +		return -EAGAIN;
> > +
> > +	paddr = virt_to_phys((void *)&priv->rx_buf);
> > +
> > +	__raw_writel(0, priv->base + GOLDFISH_TTY_DATA_PTR_HIGH);
> > +	__raw_writel(paddr, priv->base + GOLDFISH_TTY_DATA_PTR);
> > +	__raw_writel(1, priv->base + GOLDFISH_TTY_DATA_LEN);
> > +	__raw_writel(CMD_READ_BUFFER, priv->base + GOLDFISH_TTY_CMD);
> > +
> > +	return priv->rx_buf;
> > +}
> > +
> > +static int goldfish_serial_putc(struct udevice *dev, const char ch)
> > +{
> > +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> > +
> > +	__raw_writel(ch, priv->base + GOLDFISH_TTY_PUT_CHAR);
> > +
> > +	return 0;
> > +}
> > +
> > +static int goldfish_serial_pending(struct udevice *dev, bool input)
> > +{
> > +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> > +
> > +	if (input)
> > +		return __raw_readl(priv->base + GOLDFISH_TTY_BYTES_READY);
> > +
> > +	return 0;
> > +}
> > +
> > +static int goldfish_serial_probe(struct udevice *dev)
> > +{
> > +	struct goldfish_tty_priv *priv = dev_get_priv(dev);
> > +	struct goldfish_tty_plat *plat = dev_get_plat(dev);
> > +
> > +	if (!plat)
> > +		return -EINVAL;
> > +
> > +	priv->base = plat->base;
> 
> The Linux binding documentation in
> Documentation/devicetree/bindings/goldfish/tty.txt has this example:
> 
>         goldfish_tty@1f004000 {
>                 compatible = "google,goldfish-tty";
>                 reg = <0x1f004000 0x1000>;
>                 interrupts = <0xc>;
>         };
> 
> The driver should take the reg value as address and use plat->base only as
> fallback for devices that don't provide a proper device-tree.
> 
> We already do this for the RTC driver. Please, apply the same logic to all
> Goldfish drivers.

Agreed.
Will do this for both tty and timer drivers in the next version.

Regards,
Kuan-Wei

Re: [PATCH v3 3/6] rtc: goldfish: Support platform data for non-DT probing

[Kuan-Wei Chiu]

Hi Heinrich,

On Wed, Dec 31, 2025 at 01:12:45PM +0100, Heinrich Schuchardt wrote:
> On 12/30/25 17:01, Kuan-Wei Chiu wrote:
> > Currently, the Goldfish RTC driver exclusively relies on device tree
> > to retrieve the base address, failing immediately if dev_read_addr()
> > returns FDT_ADDR_T_NONE. This restriction prevents the driver from
> > being used on platforms that instantiate devices via U_BOOT_DRVINFO()
> > instead of device tree, such as the QEMU m68k virt machine.
> > 
> > Add support for platform data to address this limitation. Update the
> > probe function to fall back to retrieving the base address from
> > struct goldfish_rtc_plat if the device tree address is unavailable.
> > Introduce a new header file include/goldfish_rtc.h to define the
> > platform data structure.
> > 
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > ---
> > Changes in v3:
> > - New patch.
> > 
> > It appears there is no specific maintainer listed for this driver?
> > 
> >   drivers/rtc/goldfish_rtc.c | 10 ++++++++--
> >   include/goldfish_rtc.h     | 15 +++++++++++++++
> >   2 files changed, 23 insertions(+), 2 deletions(-)
> >   create mode 100644 include/goldfish_rtc.h
> > 
> > diff --git a/drivers/rtc/goldfish_rtc.c b/drivers/rtc/goldfish_rtc.c
> > index e63a2766c76..900daabccb9 100644
> > --- a/drivers/rtc/goldfish_rtc.c
> > +++ b/drivers/rtc/goldfish_rtc.c
> > @@ -9,6 +9,7 @@
> >   #include <div64.h>
> >   #include <dm.h>
> > +#include <goldfish_rtc.h>
> >   #include <mapmem.h>
> >   #include <rtc.h>
> >   #include <linux/io.h>
> > @@ -77,11 +78,16 @@ static int goldfish_rtc_set(struct udevice *dev, const struct rtc_time *time)
> >   static int goldfish_rtc_probe(struct udevice *dev)
> >   {
> >   	struct goldfish_rtc *priv = dev_get_priv(dev);
> > +	struct goldfish_rtc_plat *plat;
> >   	fdt_addr_t addr;
> >   	addr = dev_read_addr(dev);
> > -	if (addr == FDT_ADDR_T_NONE)
> > -		return -EINVAL;
> > +	if (addr == FDT_ADDR_T_NONE) {
> > +		plat = dev_get_plat(dev);
> > +		if (!plat)
> > +			return -EINVAL;
> > +		addr = (fdt_addr_t)plat->base;
> 
> addr is not a pointer, it is an address in the sandbox virtual memory
> address space. This is why map_sysmem() is used below.
> 
> The suggested code fails to build on sandbox_defconfig with the driver
> enabled:
> 
> drivers/rtc/goldfish_rtc.c: In function ‘goldfish_rtc_probe’:
> drivers/rtc/goldfish_rtc.c:89:24: warning: cast from pointer to integer of
> different size [-Wpointer-to-int-cast]
>    89 |                 addr = (fdt_addr_t)plat->base;
>       |
> 
> Please, use
> 
> 	priv->base = plat->base;
> 
> If plat->base is NULL, please, throw -EINVAL.

My apologies for the oversight.
I agree with your suggestion.

I will update the code to assign plat->base directly to priv->base in
the next version. I will also verify the build with sandbox_defconfig
to ensure there are no issues.

Regards,
Kuan-Wei