Merge patch series "RISC-V SBI debug console extension support"

Merge patch series "RISC-V SBI debug console extension support"

Anup Patel <apatel@ventanamicro.com> says:

The SBI v2.0 specification is now frozen. The SBI v2.0 specification defines
SBI debug console (DBCN) extension which replaces the legacy SBI v0.1
functions sbi_console_putchar() and sbi_console_getchar().
(Refer v2.0-rc5 at https://github.com/riscv-non-isa/riscv-sbi-doc/releases)

This series adds support for SBI debug console (DBCN) extension in
Linux RISC-V.

To try these patches with KVM RISC-V, use KVMTOOL from the
riscv_zbx_zicntr_smstateen_condops_v1 branch at:
https://github.com/avpatel/kvmtool.git

* b4-shazam-merge:
  RISC-V: Enable SBI based earlycon support
  tty: Add SBI debug console support to HVC SBI driver
  tty/serial: Add RISC-V SBI debug console based earlycon
  RISC-V: Add SBI debug console helper routines
  RISC-V: Add stubs for sbi_console_putchar/getchar()

Link: https://lore.kernel.org/r/20231124070905.1043092-1-apatel@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>