[PATCH v6 3/5] tty/serial: Add RISC-V SBI debug console based earlycon

Anup Patel
2024-01-19T11:35:19Z

We extend the existing RISC-V SBI earlycon support to use the new
RISC-V SBI debug console extension.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/Kconfig | 2 +-
drivers/tty/serial/earlycon-riscv-sbi.c | 27 ++++++++++++++++++++++---
2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 8b1f5756002f..ffcf4882b25f 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -87,7 +87,7 @@ config SERIAL_EARLYCON_SEMIHOST

config SERIAL_EARLYCON_RISCV_SBI
bool "Early console using RISC-V SBI"
- depends on RISCV_SBI_V01
+ depends on RISCV_SBI
select SERIAL_CORE
select SERIAL_CORE_CONSOLE
select SERIAL_EARLYCON
diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
index 27afb0b74ea7..0162155f0c83 100644
--- a/drivers/tty/serial/earlycon-riscv-sbi.c
+++ b/drivers/tty/serial/earlycon-riscv-sbi.c
@@ -15,17 +15,38 @@ static void sbi_putc(struct uart_port *port, unsigned char c)
sbi_console_putchar(c);
}

-static void sbi_console_write(struct console *con,
- const char *s, unsigned n)
+static void sbi_0_1_console_write(struct console *con,
+ const char *s, unsigned int n)
{
struct earlycon_device *dev = con->data;
uart_console_write(&dev->port, s, n, sbi_putc);
}

+static void sbi_dbcn_console_write(struct console *con,
+ const char *s, unsigned int n)
+{
+ int ret;
+
+ while (n) {
+ ret = sbi_debug_console_write(s, n);
+ if (ret < 0)
+ break;
+
+ s += ret;
+ n -= ret;
+ }
+}
+
static int __init early_sbi_setup(struct earlycon_device *device,
const char *opt)
{
- device->con->write = sbi_console_write;
+ if (sbi_debug_console_available)
+ device->con->write = sbi_dbcn_console_write;
+ else if (IS_ENABLED(CONFIG_RISCV_SBI_V01))
+ device->con->write = sbi_0_1_console_write;
+ else
+ return -ENODEV;
+
return 0;
}
EARLYCON_DECLARE(sbi, early_sbi_setup);
--
2.34.1