console: Implement flush() function

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.

Therefore introduce a new flush() and fflush() functions into console code.
These functions will call .flush callback of associated stdio_dev device.

As this function may increase U-Boot side, allow to compile U-Boot without
this function. For this purpose there is a new config CONSOLE_FLUSH_SUPPORT
which is enabled by default and can be disabled. It is a good idea to have
this option enabled for all boards which have enough space for it.

When option is disabled when U-Boot defines just empty static inline
function fflush() to avoid ifdefs in other code.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/common/Kconfig b/common/Kconfig
index b776c5ca1ec7be3da12a30e1af7824a37e4c26c5..6591acd2fd0f9a13f0624e0e5a1d441d777c3239 100644 (file)
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -186,6 +186,12 @@ config PRE_CON_BUF_ADDR
          We should consider removing this option and allocating the memory
          in board_init_f_init_reserve() instead.
 
+config CONSOLE_FLUSH_SUPPORT
+       bool "Enable console flush support"
+       default y
+       help
+         This enables compilation of flush() function for console flush support.
+
 config CONSOLE_MUX
        bool "Enable console multiplexing"
        default y if DM_VIDEO || VIDEO || LCD

diff --git a/common/console.c b/common/console.c
index e5be6ff44b02e7ce8432ffc9d00619fd081b30d3..ce0c9b69f58cb7b1f2b086950adb97e1f0d31fff 100644 (file)
--- a/common/console.c
+++ b/common/console.c
@@ -199,6 +199,7 @@ static int console_setfile(int file, struct stdio_dev * dev)
                case stdout:
                        gd->jt->putc  = putc;
                        gd->jt->puts  = puts;
+                       STDIO_DEV_ASSIGN_FLUSH(gd->jt, flush);
                        gd->jt->printf = printf;
                        break;
                }
@@ -364,6 +365,19 @@ static void console_puts(int file, const char *s)
        }
 }
 
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+static void console_flush(int file)
+{
+       int i;
+       struct stdio_dev *dev;
+
+       for_each_console_dev(i, file, dev) {
+               if (dev->flush != NULL)
+                       dev->flush(dev);
+       }
+}
+#endif
+
 #if CONFIG_IS_ENABLED(SYS_CONSOLE_IS_IN_ENV)
 static inline void console_doenv(int file, struct stdio_dev *dev)
 {
@@ -413,6 +427,14 @@ static inline void console_puts(int file, const char *s)
        stdio_devices[file]->puts(stdio_devices[file], s);
 }
 
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+static inline void console_flush(int file)
+{
+       if (stdio_devices[file]->flush)
+               stdio_devices[file]->flush(stdio_devices[file]);
+}
+#endif
+
 #if CONFIG_IS_ENABLED(SYS_CONSOLE_IS_IN_ENV)
 static inline void console_doenv(int file, struct stdio_dev *dev)
 {
@@ -526,6 +548,14 @@ void fputs(int file, const char *s)
                console_puts(file, s);
 }
 
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+void fflush(int file)
+{
+       if (file < MAX_FILES)
+               console_flush(file);
+}
+#endif
+
 int fprintf(int file, const char *fmt, ...)
 {
        va_list args;
@@ -740,6 +770,37 @@ void puts(const char *s)
        }
 }
 
+#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+void flush(void)
+{
+       if (!gd)
+               return;
+
+       /* sandbox can send characters to stdout before it has a console */
+       if (IS_ENABLED(CONFIG_SANDBOX) && !(gd->flags & GD_FLG_SERIAL_READY)) {
+               os_flush();
+               return;
+       }
+
+       if (IS_ENABLED(CONFIG_DEBUG_UART) && !(gd->flags & GD_FLG_SERIAL_READY))
+               return;
+
+       if (IS_ENABLED(CONFIG_SILENT_CONSOLE) && (gd->flags & GD_FLG_SILENT))
+               return;
+
+       if (IS_ENABLED(CONFIG_DISABLE_CONSOLE) && (gd->flags & GD_FLG_DISABLE_CONSOLE))
+               return;
+
+       if (!gd->have_console)
+               return;
+
+       if (gd->flags & GD_FLG_DEVINIT) {
+               /* Send to the standard output */
+               fflush(stdout);
+       }
+}
+#endif
+
 #ifdef CONFIG_CONSOLE_RECORD
 int console_record_init(void)
 {

diff --git a/include/_exports.h b/include/_exports.h
index f6df8b610734bc8f03a26d738276aca48b1ef5c8..1af946fac327448cea6247838ce9c107f0a1d52a 100644 (file)
--- 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/stdio.h b/include/stdio.h
index 1939a48f0fb61fc5b86a1c806e6e5b0801b22c95..3241e2d493fa2aec9d5ef14facdbc8dae3bfc545 100644 (file)
--- 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 270fa2729fb2b8b955c0d24c8f0e11523a876496..3105928970dbebd229f9152eeaacebcec1101807 100644 (file)
--- 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 */