On Fri, Dec 26, 2025 at 05:53:57PM +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 <[email protected]> > --- > Changes in v2: > - Update SPDX license identifier to GPL-2.0-or-later. > - Sort header inclusions alphabetically. > - Move RX buffer into goldfish_tty_priv instead of using a static buffer. > - Make sure getc only read a single byte at a time. > > MAINTAINERS | 6 ++ > drivers/serial/Kconfig | 8 +++ > drivers/serial/Makefile | 1 + > drivers/serial/serial_goldfish.c | 104 +++++++++++++++++++++++++++++++ > include/goldfish_tty.h | 18 ++++++ > 5 files changed, 137 insertions(+) > create mode 100644 drivers/serial/serial_goldfish.c > create mode 100644 include/goldfish_tty.h
... > diff --git a/drivers/serial/serial_goldfish.c > b/drivers/serial/serial_goldfish.c > new file mode 100644 > index 00000000000..ce5bff6bf4c > --- /dev/null > +++ b/drivers/serial/serial_goldfish.c > @@ -0,0 +1,104 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Copyright (C) 2025, Kuan-Wei Chiu <[email protected]> > + * 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 base = (unsigned long)priv->base; > + unsigned long paddr; > + u32 count; > + > + count = __raw_readl((void *)(base + GOLDFISH_TTY_BYTES_READY)); I think it's okay to do pointer arithmetic directly against priv->base in GNU C, right? In which case void * is treated like char *. If I'm correct, variable base could be dropped, and we could avoid some casts here and below. > + if (count == 0) > + return -EAGAIN; > + > + paddr = virt_to_phys((void *)&priv->rx_buf); > + > + __raw_writel(0, (void *)(base + GOLDFISH_TTY_DATA_PTR_HIGH)); > + __raw_writel(paddr, (void *)(base + GOLDFISH_TTY_DATA_PTR)); > + __raw_writel(1, (void *)(base + GOLDFISH_TTY_DATA_LEN)); > + > + __raw_writel(CMD_READ_BUFFER, (void *)(base + GOLDFISH_TTY_CMD)); > + > + return priv->rx_buf; > +} Regards, Yao Zi
