1 files changed, 63 insertions, 0 deletions
diff --git a/lib/utils/serial/litex-uart.c b/lib/utils/serial/litex-uart.c
new file mode 100644
index 0000000..f843bf3
--- /dev/null
+++ b/lib/utils/serial/litex-uart.c
@@ -0,0 +1,63 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 Gabriel Somlo
+ *
+ * Authors:
+ *   Gabriel Somlo <gsomlo@gmail.com>
+ */
+
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_console.h>
+#include <sbi_utils/serial/litex-uart.h>
+
+/* clang-format off */
+
+#define UART_REG_RXTX		0
+#define UART_REG_TXFULL		1
+#define UART_REG_RXEMPTY	2
+#define UART_REG_EV_STATUS	3
+#define UART_REG_EV_PENDING	4
+#define UART_REG_EV_ENABLE	5
+
+/* clang-format on */
+
+static volatile u32 *uart_base;
+
+static u8 get_reg(u8 reg)
+{
+	return readb(uart_base + reg);
+}
+
+static void set_reg(u8 reg, u8 val)
+{
+	writeb(val, uart_base + reg);
+}
+
+static void litex_uart_putc(char ch)
+{
+	while (get_reg(UART_REG_TXFULL));
+	set_reg(UART_REG_RXTX, ch);
+}
+
+static int litex_uart_getc(void)
+{
+	if (get_reg(UART_REG_RXEMPTY))
+		return -1;
+	else
+		return get_reg(UART_REG_RXTX);
+}
+
+static struct sbi_console_device litex_console = {
+	.name = "litex_uart",
+	.console_putc = litex_uart_putc,
+	.console_getc = litex_uart_getc
+};
+
+int litex_uart_init(unsigned long base)
+{
+	uart_base = (volatile u32 *)base;
+	set_reg(UART_REG_EV_ENABLE, 0); /* UART in polling mode: disable IRQ */
+	sbi_console_set_device(&litex_console);
+	return 0;
+}