From 27de1f541f1f911bc2242ae68ef7375247b36c7d Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Tue, 4 Dec 2018 19:25:05 +0530 Subject: tty/serial: Add RISC-V SBI earlycon support In RISC-V, the M-mode runtime firmware provide SBI calls for debug prints. This patch adds earlycon support using RISC-V SBI console calls. To enable it, just pass "earlycon=sbi" in kernel parameters. Signed-off-by: Anup Patel Acked-by: Greg Kroah-Hartman Reviewed-by: Palmer Dabbelt Signed-off-by: Palmer Dabbelt --- drivers/tty/serial/Kconfig | 12 ++++++++++++ drivers/tty/serial/Makefile | 1 + drivers/tty/serial/earlycon-riscv-sbi.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 41 insertions(+) create mode 100644 drivers/tty/serial/earlycon-riscv-sbi.c (limited to 'drivers/tty') diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 67b9bf3b500e..089a6f285d5e 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -85,6 +85,18 @@ config SERIAL_EARLYCON_ARM_SEMIHOST with "earlycon=smh" on the kernel command line. The console is enabled when early_param is processed. +config SERIAL_EARLYCON_RISCV_SBI + bool "Early console using RISC-V SBI" + depends on RISCV + select SERIAL_CORE + select SERIAL_CORE_CONSOLE + select SERIAL_EARLYCON + help + Support for early debug console using RISC-V SBI. This enables + the console before standard serial driver is probed. This is enabled + with "earlycon=sbi" on the kernel command line. The console is + enabled when early_param is processed. + config SERIAL_SB1250_DUART tristate "BCM1xxx on-chip DUART serial support" depends on SIBYTE_SB1xxx_SOC=y diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index 8c303736b7e8..1511e8a9f856 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -7,6 +7,7 @@ obj-$(CONFIG_SERIAL_CORE) += serial_core.o obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o obj-$(CONFIG_SERIAL_EARLYCON_ARM_SEMIHOST) += earlycon-arm-semihost.o +obj-$(CONFIG_SERIAL_EARLYCON_RISCV_SBI) += earlycon-riscv-sbi.o # These Sparc drivers have to appear before others such as 8250 # which share ttySx minor node space. Otherwise console device diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c new file mode 100644 index 000000000000..e1a551aae336 --- /dev/null +++ b/drivers/tty/serial/earlycon-riscv-sbi.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * RISC-V SBI based earlycon + * + * Copyright (C) 2018 Anup Patel + */ +#include +#include +#include +#include +#include + +static void sbi_console_write(struct console *con, + const char *s, unsigned int n) +{ + int i; + + for (i = 0; i < n; ++i) + sbi_console_putchar(s[i]); +} + +static int __init early_sbi_setup(struct earlycon_device *device, + const char *opt) +{ + device->con->write = sbi_console_write; + return 0; +} +EARLYCON_DECLARE(sbi, early_sbi_setup); -- cgit v1.2.3