Unless you have a spare Apple Silicon machine, getting access to the serial port on Apple Silicon machines requires special hardware. Given that most machines come with a built-in screen the framebuffer is likely to be the most convenient output device for most users. While U-Boot will output to both serial and framebuffer, OSes might not. Therefore set stdout-path to point at /chosen/framebuffer when a keyboard is connected to the machine.

This behaviour can be overridden by setting the "stdout" variable in the U-Boot environment. I addition to that keep the serial console as the default when running under the m1n1 hypervisor. The m1n1 hypervisor virtualizes the serial port such that it can be easily accessed from any other machine with a USB port.

Signed-off-by: Mark Kettenis kettenis@openbsd.org Reviewed-by: Janne Grunau j@jannau.net Tested-by: Janne Grunau j@jannau.net --- arch/arm/Kconfig | 1 + arch/arm/mach-apple/board.c | 40 +++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index efe33a58e1..138ba1b073 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -994,6 +994,7 @@ config ARCH_APPLE select DM_VIDEO select IOMMU select LINUX_KERNEL_IMAGE_HEADER + select OF_BOARD_SETUP select OF_CONTROL select PINCTRL select POSITION_INDEPENDENT diff --git a/arch/arm/mach-apple/board.c b/arch/arm/mach-apple/board.c index ffc1301cf5..1525a9edee 100644 --- a/arch/arm/mach-apple/board.c +++ b/arch/arm/mach-apple/board.c @@ -5,6 +5,7 @@

#include <common.h> #include <dm.h> +#include <dm/uclass-internal.h> #include <efi_loader.h> #include <lmb.h>

@@ -461,3 +462,42 @@ int board_late_init(void)

return 0; } + +int ft_board_setup(void *blob, struct bd_info *bd) +{ + struct udevice *dev; + const char *stdoutname; + int node, ret; + + /* + * Modify the "stdout-path" property under "/chosen" to point + * at "/chosen/framebuffer if a keyboard is available and + * we're not running under the m1n1 hypervisor. + * Developers can override this behaviour by dropping + * "vidconsole" from the "stdout" environment variable. + */ + + /* EL1 means we're running under the m1n1 hypervisor. */ + if (current_el() == 1) + return 0; + + ret = uclass_find_device(UCLASS_KEYBOARD, 0, &dev); + if (ret < 0) + return 0; + + stdoutname = env_get("stdout"); + if (!stdoutname || !strstr(stdoutname, "vidconsole")) + return 0; + + /* Make sure we actually have a framebuffer. */ + node = fdt_path_offset(blob, "/chosen/framebuffer"); + if (node < 0 || !fdtdec_get_is_enabled(blob, node)) + return 0; + + node = fdt_path_offset(blob, "/chosen"); + if (node < 0) + return 0; + fdt_setprop_string(blob, node, "stdout-path", "/chosen/framebuffer"); + + return 0; +}