1 files changed, 52 insertions, 0 deletions
diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
new file mode 100644
index 000000000000..0162155f0c83
--- /dev/null
+++ b/drivers/tty/serial/earlycon-riscv-sbi.c
@@ -0,0 +1,52 @@
+// 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_putc(struct uart_port *port, unsigned char c)
+{
+	sbi_console_putchar(c);
+}
+
+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)
+{
+	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);