IOMUX: Add console multiplexing support.

Modifications to support console multiplexing.  This is controlled using
CONFIG_SYS_CONSOLE_MUX in the board configuration file.

This allows a user to specify multiple console devices in the environment
with a command like this: setenv stdin serial,nc.  As a result, the user can
enter text on both the serial and netconsole interfaces.

All devices - stdin, stdout and stderr - can be set in this manner.

1) common/iomux.c and include/iomux.h contain the environment setting
implementation.
2) doc/README.iomux contains a somewhat more detailed description.
3) The implementation in (1) is called from common/cmd_nvedit.c to
handle setenv and from common/console.c to handle initialization of
input/output devices at boot time.
4) common/console.c also contains the code needed to poll multiple console
devices for input and send output to all devices registered for output.
5) include/common.h includes iomux.h and common/Makefile generates iomux.o
when CONFIG_SYS_CONSOLE_MUX is set.

Signed-off-by: Gary Jennejohn <garyj@denx.de>

1 files changed, 155 insertions, 1 deletions

diff --git a/common/console.c b/common/console.c
index 6f0846f..89aeab6 100644
--- a/common/console.c
+++ b/common/console.c
@@ -93,6 +93,76 @@ static int console_setfile (int file, device_t * dev)
 	return error;
 }
 
+#if defined(CONFIG_CONSOLE_MUX)
+/** Console I/O multiplexing *******************************************/
+
+static device_t *tstcdev;
+device_t **console_devices[MAX_FILES];
+int cd_count[MAX_FILES];
+
+/*
+ * This depends on tstc() always being called before getc().
+ * This is guaranteed to be true because this routine is called
+ * only from fgetc() which assures it.
+ * No attempt is made to demultiplex multiple input sources.
+ */
+static int iomux_getc(void)
+{
+	unsigned char ret;
+
+	/* This is never called with testcdev == NULL */
+	ret = tstcdev->getc();
+	tstcdev = NULL;
+	return ret;
+}
+
+static int iomux_tstc(int file)
+{
+	int i, ret;
+	device_t *dev;
+
+	disable_ctrlc(1);
+	for (i = 0; i < cd_count[file]; i++) {
+		dev = console_devices[file][i];
+		if (dev->tstc != NULL) {
+			ret = dev->tstc();
+			if (ret > 0) {
+				tstcdev = dev;
+				disable_ctrlc(0);
+				return ret;
+			}
+		}
+	}
+	disable_ctrlc(0);
+
+	return 0;
+}
+
+static void iomux_putc(int file, const char c)
+{
+	int i;
+	device_t *dev;
+
+	for (i = 0; i < cd_count[file]; i++) {
+		dev = console_devices[file][i];
+		if (dev->putc != NULL)
+			dev->putc(c);
+	}
+}
+
+static void iomux_puts(int file, const char *s)
+{
+	int i;
+	device_t *dev;
+
+	for (i = 0; i < cd_count[file]; i++) {
+		dev = console_devices[file][i];
+		if (dev->puts != NULL)
+			dev->puts(s);
+	}
+}
+#endif /* defined(CONFIG_CONSOLE_MUX) */
+
 /** U-Boot INITIAL CONSOLE-NOT COMPATIBLE FUNCTIONS *************************/
 
 void serial_printf (const char *fmt, ...)
@@ -114,8 +184,31 @@ void serial_printf (const char *fmt, ...)
 
 int fgetc (int file)
 {
-	if (file < MAX_FILES)
+	if (file < MAX_FILES) {
+#if defined(CONFIG_CONSOLE_MUX)
+		/*
+		 * Effectively poll for input wherever it may be available.
+		 */
+		for (;;) {
+			/*
+			 * Upper layer may have already called tstc() so
+			 * check for that first.
+			 */
+			if (tstcdev != NULL)
+				return iomux_getc();
+			iomux_tstc(file);
+#ifdef CONFIG_WATCHDOG
+			/*
+			 * If the watchdog must be rate-limited then it should
+			 * already be handled in board-specific code.
+			 */
+			 udelay(1);
+#endif
+		}
+#else
 		return stdio_devices[file]->getc ();
+#endif
+	}
 
 	return -1;
 }
@@ -123,7 +216,11 @@ int fgetc (int file)
 int ftstc (int file)
 {
 	if (file < MAX_FILES)
+#if defined(CONFIG_CONSOLE_MUX)
+		return iomux_tstc(file);
+#else
 		return stdio_devices[file]->tstc ();
+#endif
 
 	return -1;
 }
@@ -131,13 +228,21 @@ int ftstc (int file)
 void fputc (int file, const char c)
 {
 	if (file < MAX_FILES)
+#if defined(CONFIG_CONSOLE_MUX)
+		iomux_putc(file, c);
+#else
 		stdio_devices[file]->putc (c);
+#endif
 }
 
 void fputs (int file, const char *s)
 {
 	if (file < MAX_FILES)
+#if defined(CONFIG_CONSOLE_MUX)
+		iomux_puts(file, s);
+#else
 		stdio_devices[file]->puts (s);
+#endif
 }
 
 void fprintf (int file, const char *fmt, ...)
@@ -407,6 +512,9 @@ int console_init_r (void)
 #ifdef CONFIG_SYS_CONSOLE_ENV_OVERWRITE
 	int i;
 #endif /* CONFIG_SYS_CONSOLE_ENV_OVERWRITE */
+#ifdef CONFIG_CONSOLE_MUX
+	int iomux_err = 0;
+#endif
 
 	/* set default handlers at first */
 	gd->jt[XF_getc] = serial_getc;
@@ -425,6 +533,14 @@ int console_init_r (void)
 		inputdev  = search_device (DEV_FLAGS_INPUT,  stdinname);
 		outputdev = search_device (DEV_FLAGS_OUTPUT, stdoutname);
 		errdev    = search_device (DEV_FLAGS_OUTPUT, stderrname);
+#ifdef CONFIG_CONSOLE_MUX
+		iomux_err = iomux_doenv(stdin, stdinname);
+		iomux_err += iomux_doenv(stdout, stdoutname);
+		iomux_err += iomux_doenv(stderr, stderrname);
+		if (!iomux_err)
+			/* Successful, so skip all the code below. */
+			goto done;
+#endif
 	}
 	/* if the devices are overwritten or not found, use default device */
 	if (inputdev == NULL) {
@@ -438,15 +554,34 @@ int console_init_r (void)
 	}
 	/* Initializes output console first */
 	if (outputdev != NULL) {
+#ifdef CONFIG_CONSOLE_MUX
+		/* need to set a console if not done above. */
+		iomux_doenv(stdout, outputdev->name);
+#else
 		console_setfile (stdout, outputdev);
+#endif
 	}
 	if (errdev != NULL) {
+#ifdef CONFIG_CONSOLE_MUX
+		/* need to set a console if not done above. */
+		iomux_doenv(stderr, errdev->name);
+#else
 		console_setfile (stderr, errdev);
+#endif
 	}
 	if (inputdev != NULL) {
+#ifdef CONFIG_CONSOLE_MUX
+		/* need to set a console if not done above. */
+		iomux_doenv(stdin, inputdev->name);
+#else
 		console_setfile (stdin, inputdev);
+#endif
 	}
 
+#ifdef CONFIG_CONSOLE_MUX
+done:
+#endif
+
 	gd->flags |= GD_FLG_DEVINIT;	/* device initialization completed */
 
 #ifndef CONFIG_SYS_CONSOLE_INFO_QUIET
@@ -455,21 +590,33 @@ int console_init_r (void)
 	if (stdio_devices[stdin] == NULL) {
 		puts ("No input devices available!\n");
 	} else {
+#ifdef CONFIG_CONSOLE_MUX
+		iomux_printdevs(stdin);
+#else
 		printf ("%s\n", stdio_devices[stdin]->name);
+#endif
 	}
 
 	puts ("Out:   ");
 	if (stdio_devices[stdout] == NULL) {
 		puts ("No output devices available!\n");
 	} else {
+#ifdef CONFIG_CONSOLE_MUX
+		iomux_printdevs(stdout);
+#else
 		printf ("%s\n", stdio_devices[stdout]->name);
+#endif
 	}
 
 	puts ("Err:   ");
 	if (stdio_devices[stderr] == NULL) {
 		puts ("No error devices available!\n");
 	} else {
+#ifdef CONFIG_CONSOLE_MUX
+		iomux_printdevs(stderr);
+#else
 		printf ("%s\n", stdio_devices[stderr]->name);
+#endif
 	}
 #endif /* CONFIG_SYS_CONSOLE_INFO_QUIET */
 
@@ -524,11 +671,18 @@ int console_init_r (void)
 	if (outputdev != NULL) {
 		console_setfile (stdout, outputdev);
 		console_setfile (stderr, outputdev);
+#ifdef CONFIG_CONSOLE_MUX
+		console_devices[stdout][0] = outputdev;
+		console_devices[stderr][0] = outputdev;
+#endif
 	}
 
 	/* Initializes input console */
 	if (inputdev != NULL) {
 		console_setfile (stdin, inputdev);
+#ifdef CONFIG_CONSOLE_MUX
+		console_devices[stdin][0] = inputdev;
+#endif
 	}
 
 	gd->flags |= GD_FLG_DEVINIT;	/* device initialization completed */