diff options
| author | Bin Meng <bmeng@tinylab.org> | 2022-12-09 23:04:36 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-19 14:58:19 +0100 |
| commit | db5489f4be000cbb7e7ce9cc1a264c5d3d25b56f (patch) | |
| tree | 5750889ce8f55be25cbd33fc8419d7c95d3acbe9 /arch/riscv/include/asm/semihost.h | |
| parent | 8890717526c8e13801f7e866329a2bfce3a62240 (diff) | |
riscv: Implement semihost.h for earlycon semihost driver
Per RISC-V semihosting spec [1], implement semihost.h for the existing
Arm semihosting earlycon driver to work on RISC-V.
Link: https://github.com/riscv/riscv-semihosting-spec/blob/main/riscv-semihosting-spec.adoc [1]
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Tested-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20221209150437.795918-3-bmeng@tinylab.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/riscv/include/asm/semihost.h')
| -rw-r--r-- | arch/riscv/include/asm/semihost.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/semihost.h b/arch/riscv/include/asm/semihost.h new file mode 100644 index 000000000000..557a34938193 --- /dev/null +++ b/arch/riscv/include/asm/semihost.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2022 tinylab.org + * Author: Bin Meng <bmeng@tinylab.org> + */ + +#ifndef _RISCV_SEMIHOST_H_ +#define _RISCV_SEMIHOST_H_ + +struct uart_port; + +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"); +} + +#endif /* _RISCV_SEMIHOST_H_ */ |