Add ESP32C3 RISC-V stub
diff --git a/src/kernel/riscv32/serial-generic.c b/src/kernel/riscv32/serial-generic.c
new file mode 100644
index 0000000..ea231d9
--- /dev/null
+++ b/src/kernel/riscv32/serial-generic.c
@@ -0,0 +1,35 @@
+#include "kint.h"
+#include "serial.h"
+
+/* Base address for QEMU */
+/* TODO: Abstract for ESP32C3 */
+#define UART_BASE (void *)0x10000000
+#define UART_LSR_EMPTY_MASK 0x40
+
+/* UART transmitter holding register */
+uchar *uart_thr = UART_BASE;
+
+/* UART line status register */
+uchar *uart_lsr = UART_BASE + 5;
+
+void init_serial()
+{
+}
+
+void serial_put(char byte)
+{
+ while (*uart_lsr ^ UART_LSR_EMPTY_MASK)
+ {
+ /* block until UART clear */
+ }
+
+ *uart_thr = byte;
+}
+
+void serial_write(char *string)
+{
+ while (*string)
+ {
+ serial_put(*string++);
+ }
+}