Per RISC-V semihosting spec [1], implement semihost.h for the existing Arm semihosting earlycon driver to work on RISC-V. [1] https://github.com/riscv/riscv-semihosting-spec/blob/main/riscv-semihosting-spec.adoc Signed-off-by: Bin Meng <bmeng@xxxxxxxxxxx> --- Changes in v2: - Move the RISC-V implementation to semihost.h arch/riscv/include/asm/semihost.h | 19 +++++++++++++++++++ drivers/tty/serial/Kconfig | 2 +- 2 files changed, 20 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/include/asm/semihost.h diff --git a/arch/riscv/include/asm/semihost.h b/arch/riscv/include/asm/semihost.h new file mode 100644 index 000000000000..886f21d7a476 --- /dev/null +++ b/arch/riscv/include/asm/semihost.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2022 tinylab.org + * Author: Bin Meng <bmeng@xxxxxxxxxxx> + */ + +static inline void smh_putc(struct uart_port *port, unsigned char c) +{ + asm volatile("addi a1, %0, 0\n" + "addi a0, zero, 3\n" + ".balign 16\n" + ".option push\n" + ".option norvc\n" + "slli zero, zero, 0x1f\n" + "ebreak\n" + "srai zero, zero, 0x7\n" + ".option pop\n" + : : "r" (&c) : "a0", "a1", "memory"); +} diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 434f83168546..e94d1265151c 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -75,7 +75,7 @@ config SERIAL_AMBA_PL011_CONSOLE config SERIAL_EARLYCON_ARM_SEMIHOST bool "Early console using ARM semihosting" - depends on ARM64 || ARM + depends on ARM64 || ARM || RISCV select SERIAL_CORE select SERIAL_CORE_CONSOLE select SERIAL_EARLYCON -- 2.34.1
