[0/2] Add generic framebuffer support to EFI earlycon driver

Message

Markuss Broks July 28, 2022, 2:28 p.m. UTC

Make the EFI earlycon driver be suitable for any linear framebuffers.
This should be helpful for early porting of boards with no other means of
output, like smartphones/tablets. There seems to be an issue with early_ioremap
function on ARM32, but I am unable to find the exact cause. It appears the mappings
returned by it are somehow incorrect, thus the driver is disabled on ARM. EFI early
console was disabled on IA64 previously, so I kept it in EFI earlycon Kconfig.

This patch also changes behavior on EFI systems, by selecting the mapping type
based on if the framebuffer region intersects with system RAM. If it does, it's
common sense that it should be in RAM as a whole, and so the system RAM mapping is
used. It was tested to be working on my PC (Intel Z490 platform).

Markuss Broks (2):
  drivers: serial: earlycon: Pass device-tree node
  efi: earlycon: Add support for generic framebuffers and move to fbdev
    subsystem

 .../admin-guide/kernel-parameters.txt         |  12 +-
 MAINTAINERS                                   |   5 +
 drivers/firmware/efi/Kconfig                  |   6 +-
 drivers/firmware/efi/Makefile                 |   1 -
 drivers/firmware/efi/earlycon.c               | 246 --------------
 drivers/tty/serial/earlycon.c                 |   3 +
 drivers/video/fbdev/Kconfig                   |  11 +
 drivers/video/fbdev/Makefile                  |   1 +
 drivers/video/fbdev/earlycon.c                | 301 ++++++++++++++++++
 include/linux/serial_core.h                   |   1 +
 10 files changed, 331 insertions(+), 256 deletions(-)
 delete mode 100644 drivers/firmware/efi/earlycon.c
 create mode 100644 drivers/video/fbdev/earlycon.c