[console][io] Add an optional global input queue.

In this model, getc reads from a global input buffer and the uart posts data to this buffer.

This commit also enables the global input queue for STM32F7 and QEMU-Virt.

Tested on STM32F7/Dartuino and QEMU-ARM A15 with both CONSOLE_HAS_INPUT_BUFFER=1 and CONSOLE_HAS_INPUT_BUFFER=0

lib/io/console.c

@@ -28,10 +28,12 @@
 #include <assert.h>
 #include <list.h>
 #include <string.h>
+#include <lib/cbuf.h>
 #include <arch/ops.h>
 #include <platform.h>
 #include <platform/debug.h>
 #include <kernel/thread.h>
+#include <lk/init.h>
 
 /* routines for dealing with main console io */
 
@@ -44,6 +46,16 @@
 static spin_lock_t print_spin_lock = 0;
 static struct list_node print_callbacks = LIST_INITIAL_VALUE(print_callbacks);
 
+#if CONSOLE_HAS_INPUT_BUFFER
+#ifndef CONSOLE_BUF_LEN
+#define CONSOLE_BUF_LEN 256
+#endif
+
+/* global input circular buffer */
+cbuf_t console_input_cbuf;
+static uint8_t console_cbuf_buf[CONSOLE_BUF_LEN];
+#endif // CONSOLE_HAS_INPUT_BUFFER
+
 /* print lock must be held when invoking out, outs, outc */
 static void out_count(const char *str, size_t len)
 {
@@ -100,13 +112,27 @@ static ssize_t __debug_stdio_read(io_handle_t *io, char *s, size_t len)
     if (len == 0)
         return 0;
 
+#if CONSOLE_HAS_INPUT_BUFFER
+    ssize_t err = cbuf_read(&console_input_cbuf, s, len, true);
+    return err;
+#else
     int err = platform_dgetc(s, true);
     if (err < 0)
         return err;
 
     return 1;
+#endif
 }
 
+#if CONSOLE_HAS_INPUT_BUFFER
+void console_init_hook(uint level)
+{
+    cbuf_initialize_etc(&console_input_cbuf, sizeof(console_cbuf_buf), console_cbuf_buf);
+}
+
+LK_INIT_HOOK(console, console_init_hook, LK_INIT_LEVEL_PLATFORM_EARLY - 1);
+#endif
+
 /* global console io handle */
 static const io_handle_hooks_t console_io_hooks = {
     .write  = __debug_stdio_write,
@@ -114,3 +140,4 @@ static const io_handle_hooks_t console_io_hooks = {
 };
 
 io_handle_t console_io = IO_HANDLE_INITIAL_VALUE(&console_io_hooks);
+

lib/io/include/lib/io.h

@@ -70,5 +70,14 @@ static inline void io_handle_init(io_handle_t *io, io_handle_hooks_t *hooks)
 /* the main console io handle */
 extern io_handle_t console_io;
 
+#ifndef CONSOLE_HAS_INPUT_BUFFER
+#define CONSOLE_HAS_INPUT_BUFFER 0
+#endif
+
+#if CONSOLE_HAS_INPUT_BUFFER
+/* main input circular buffer that acts as the default input queue */
+typedef struct cbuf cbuf_t;
+extern cbuf_t console_input_cbuf;
+#endif
 
 __END_CDECLS

lib/io/rules.mk

@@ -3,6 +3,7 @@ LOCAL_DIR := $(GET_LOCAL_DIR)
 MODULE := $(LOCAL_DIR)
 
 MODULE_DEPS := \
+	lib/cbuf
 
 MODULE_SRCS += \
    $(LOCAL_DIR)/console.c \