From af621ec91bda512fccfe9505ed0a6708335fa9e5 Mon Sep 17 00:00:00 2001
From: Gunar Schorcht <gunar@schorcht.net>
Date: Sat, 25 Dec 2021 13:12:16 +0100
Subject: [PATCH] sys/usb/cdc/acm: implementation of stdio_available

---
 makefiles/stdio.inc.mk                | 1 +
 sys/usb/usbus/cdc/acm/Kconfig         | 1 +
 sys/usb/usbus/cdc/acm/cdc_acm_stdio.c | 7 +++++++
 3 files changed, 9 insertions(+)

diff --git a/makefiles/stdio.inc.mk b/makefiles/stdio.inc.mk
index 462f902a96..477bb6d97e 100644
--- a/makefiles/stdio.inc.mk
+++ b/makefiles/stdio.inc.mk
@@ -17,6 +17,7 @@ endif
 ifneq (,$(filter stdio_cdc_acm,$(USEMODULE)))
   USEMODULE += usbus_cdc_acm
   USEMODULE += isrpipe
+  USEMODULE += stdio_available
 endif
 
 ifneq (,$(filter stdio_rtt,$(USEMODULE)))
diff --git a/sys/usb/usbus/cdc/acm/Kconfig b/sys/usb/usbus/cdc/acm/Kconfig
index 68a8ea1d1f..42c2866452 100644
--- a/sys/usb/usbus/cdc/acm/Kconfig
+++ b/sys/usb/usbus/cdc/acm/Kconfig
@@ -58,5 +58,6 @@ config MODULE_STDIO_CDC_ACM
     bool "CDC ACM"
     depends on MODULE_USBUS_CDC_ACM
     select MODULE_ISRPIPE
+    select MODULE_STDIO_AVAILABLE
 
 endchoice
diff --git a/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c b/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c
index 568eddf703..a145b03412 100644
--- a/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c
+++ b/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c
@@ -51,6 +51,13 @@ void stdio_init(void)
 #endif
 }
 
+#if IS_USED(MODULE_STDIO_AVAILABLE)
+int stdio_available(void)
+{
+    return tsrb_avail(&_cdc_stdio_isrpipe.tsrb);
+}
+#endif
+
 ssize_t stdio_read(void* buffer, size_t len)
 {
     (void)buffer;