Merge branch '2022-09-24-add-console-flush' into next

To quote the author:
On certain places it is required to flush output print buffers to ensure
that text strings were sent to console or serial devices. For example when
printing message that U-Boot is going to boot kernel or when U-Boot is
going to change baudrate of terminal device.

Some console devices, like UART, have putc/puts functions which just put
characters into HW transmit queue and do not wait until all data are
transmitted. Doing some sensitive operations (like changing baudrate or
starting kernel which resets UART HW) cause that U-Boot messages are lost.

Therefore introduce a new flush() function, implement it for all serial
devices via pending(false) callback and use this new flush() function on
sensitive places after which output device may go into reset state.

This change fixes printing of U-Boot messages:
"## Starting application at ..."
"## Switch baudrate to ..."

In addition, take a patch from Heinrich to rename some EFI test
functions in order to not conflict with this series.

5 files changed, 38 insertions, 0 deletions

diff --git a/include/_exports.h b/include/_exports.h
index f6df8b61073..1af946fac32 100644
--- a/include/_exports.h
+++ b/include/_exports.h
@@ -12,6 +12,9 @@
 	EXPORT_FUNC(tstc, int, tstc, void)
 	EXPORT_FUNC(putc, void, putc, const char)
 	EXPORT_FUNC(puts, void, puts, const char *)
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+	EXPORT_FUNC(flush, void, flush, void)
+#endif
 	EXPORT_FUNC(printf, int, printf, const char*, ...)
 #if (defined(CONFIG_X86) && !defined(CONFIG_X86_64)) || defined(CONFIG_PPC)
 	EXPORT_FUNC(irq_install_handler, void, install_hdlr,
diff --git a/include/os.h b/include/os.h
index 148178787bc..5b353ae9d94 100644
--- a/include/os.h
+++ b/include/os.h
@@ -296,6 +296,14 @@ void os_putc(int ch);
 void os_puts(const char *str);
 
 /**
+ * os_flush() - flush controlling OS terminal
+ *
+ * This bypasses the U-Boot console support and flushes directly the OS
+ * stdout file descriptor.
+ */
+void os_flush(void);
+
+/**
  * os_write_ram_buf() - write the sandbox RAM buffer to a existing file
  *
  * @fname:	filename to write memory to (simple binary format)
diff --git a/include/serial.h b/include/serial.h
index 8c2e7adbc32..fe01bcfadb9 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -362,6 +362,11 @@ void serial_setbrg(void);
 void serial_putc(const char ch);
 void serial_putc_raw(const char ch);
 void serial_puts(const char *str);
+#if defined(CONFIG_CONSOLE_FLUSH_SUPPORT) && CONFIG_IS_ENABLED(DM_SERIAL)
+void serial_flush(void);
+#else
+static inline void serial_flush(void) {}
+#endif
 int serial_getc(void);
 int serial_tstc(void);
 
diff --git a/include/stdio.h b/include/stdio.h
index 1939a48f0fb..3241e2d493f 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -15,6 +15,11 @@ int tstc(void);
 		defined(CONFIG_SPL_SERIAL))
 void putc(const char c);
 void puts(const char *s);
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+void flush(void);
+#else
+static inline void flush(void) {}
+#endif
 int __printf(1, 2) printf(const char *fmt, ...);
 int vprintf(const char *fmt, va_list args);
 #else
@@ -26,6 +31,10 @@ static inline void puts(const char *s)
 {
 }
 
+static inline void flush(void)
+{
+}
+
 static inline int __printf(1, 2) printf(const char *fmt, ...)
 {
 	return 0;
@@ -48,11 +57,17 @@ static inline int vprintf(const char *fmt, va_list args)
 /* stderr */
 #define eputc(c)		fputc(stderr, c)
 #define eputs(s)		fputs(stderr, s)
+#define eflush()		fflush(stderr)
 #define eprintf(fmt, args...)	fprintf(stderr, fmt, ##args)
 
 int __printf(2, 3) fprintf(int file, const char *fmt, ...);
 void fputs(int file, const char *s);
 void fputc(int file, const char c);
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+void fflush(int file);
+#else
+static inline void fflush(int file) {}
+#endif
 int ftstc(int file);
 int fgetc(int file);
 
diff --git a/include/stdio_dev.h b/include/stdio_dev.h
index 270fa2729fb..3105928970d 100644
--- a/include/stdio_dev.h
+++ b/include/stdio_dev.h
@@ -37,6 +37,13 @@ struct stdio_dev {
 	void (*putc)(struct stdio_dev *dev, const char c);
 	/* To put a string (accelerator) */
 	void (*puts)(struct stdio_dev *dev, const char *s);
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+	/* To flush output queue */
+	void (*flush)(struct stdio_dev *dev);
+#define STDIO_DEV_ASSIGN_FLUSH(dev, flush_func) ((dev)->flush = (flush_func))
+#else
+#define STDIO_DEV_ASSIGN_FLUSH(dev, flush_func)
+#endif
 
 /* INPUT functions */