tty/serial: Add RISC-V SBI debug console based earlycon

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>
Link: https://lore.kernel.org/r/20231124070905.1043092-4-apatel@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 732c893c8d161815b476bf815ee689c92e3f25a9..1f2594b8ab9d8bbcaff9a5f14dc5cb93f57aa222 100644 (file)
--- 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 27afb0b74ea705bebbc3895b577ddc39b4eda6b6..0162155f0c83976e5aa9b014974fdf413f3b4a45 100644 (file)
--- 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);