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| author | Anup Patel <anup@brainfault.org> | 2018-12-04 19:25:05 +0530 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@sifive.com> | 2019-01-09 14:59:57 -0800 |
| commit | 27de1f541f1f911bc2242ae68ef7375247b36c7d (patch) | |
| tree | 1f88825dd6ee4aa8424f9f71f9ca1e6a0aed3158 /drivers/tty | |
| parent | 801009424e05cf110f016d7fac7fcf20ef94941a (diff) | |
| download | linux-stable-27de1f541f1f911bc2242ae68ef7375247b36c7d.tar.gz linux-stable-27de1f541f1f911bc2242ae68ef7375247b36c7d.tar.bz2 linux-stable-27de1f541f1f911bc2242ae68ef7375247b36c7d.zip | |
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 <anup@brainfault.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/tty/serial/Makefile | 1 | ||||
| -rw-r--r-- | drivers/tty/serial/earlycon-riscv-sbi.c | 28 |
3 files changed, 41 insertions, 0 deletions
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 <anup@brainfault.org> + */ +#include <linux/kernel.h> +#include <linux/console.h> +#include <linux/init.h> +#include <linux/serial_core.h> +#include <asm/sbi.h> + +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); |