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>

common/Makefile

@@ -142,6 +142,7 @@ COBJS-$(CONFIG_VFD) += cmd_vfd.o
 # others
 COBJS-$(CONFIG_DDR_SPD) += ddr_spd.o
 COBJS-$(CONFIG_CMD_DOC) += docecc.o
+COBJS-$(CONFIG_CONSOLE_MUX) += iomux.o
 COBJS-y += flash.o
 COBJS-y += kgdb.o
 COBJS-$(CONFIG_LCD) += lcd.o

common/cmd_nvedit.c

@@ -213,6 +213,11 @@ int _do_setenv (int flag, int argc, char *argv[])
 				return 1;
 			}
 
+#ifdef CONFIG_CONSOLE_MUX
+			i = iomux_doenv(console, argv[2]);
+			if (i)
+				return i;
+#else
 			/* Try assigning specified device */
 			if (console_assign (console, argv[2]) < 0)
 				return 1;
@@ -221,6 +226,7 @@ int _do_setenv (int flag, int argc, char *argv[])
 			if (serial_assign (argv[2]) < 0)
 				return 1;
 #endif
+#endif /* CONFIG_CONSOLE_MUX */
 		}
 
 		/*

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 */

common/iomux.c

@@ -0,0 +1,175 @@
+/*
+ * (C) Copyright 2008
+ * Gary Jennejohn, DENX Software Engineering GmbH, garyj@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <serial.h>
+#include <malloc.h>
+
+#ifdef CONFIG_CONSOLE_MUX
+void iomux_printdevs(const int console)
+{
+	int i;
+	device_t *dev;
+
+	for (i = 0; i < cd_count[console]; i++) {
+		dev = console_devices[console][i];
+		printf("%s ", dev->name);
+	}
+	printf("\n");
+}
+
+/* This tries to preserve the old list if an error occurs. */
+int iomux_doenv(const int console, const char *arg)
+{
+	char *console_args, *temp, **start;
+	int i, j, k, io_flag, cs_idx, repeat;
+	device_t *dev;
+	device_t **cons_set;
+
+	console_args = strdup(arg);
+	if (console_args == NULL)
+		return 1;
+	/*
+	 * Check whether a comma separated list of devices was
+	 * entered and count how many devices were entered.
+	 * The array start[] has pointers to the beginning of
+	 * each device name (up to MAX_CONSARGS devices).
+	 *
+	 * Have to do this twice - once to count the number of
+	 * commas and then again to populate start.
+	 */
+	i = 0;
+	temp = console_args;
+	for (;;) {
+		temp = strchr(temp, ',');
+		if (temp != NULL) {
+			i++;
+			temp++;
+			continue;
+		}
+		/* There's always one entry more than the number of commas. */
+		i++;
+		break;
+	}
+	start = (char **)malloc(i * sizeof(char *));
+	if (start == NULL) {
+		free(console_args);
+		return 1;
+	}
+	i = 0;
+	start[0] = console_args;
+	for (;;) {
+		temp = strchr(start[i++], ',');
+		if (temp == NULL)
+			break;
+		*temp = '\0';
+		start[i] = temp + 1;
+	}
+	cons_set = (device_t **)calloc(i, sizeof(device_t *));
+	if (cons_set == NULL) {
+		free(start);
+		free(console_args);
+		return 1;
+	}
+
+	switch (console) {
+	case stdin:
+		io_flag = DEV_FLAGS_INPUT;
+		break;
+	case stdout:
+	case stderr:
+		io_flag = DEV_FLAGS_OUTPUT;
+		break;
+	default:
+		free(start);
+		free(console_args);
+		free(cons_set);
+		return 1;
+	}
+
+	cs_idx = 0;
+	for (j = 0; j < i; j++) {
+		/*
+		 * Check whether the device exists and is valid.
+		 * console_assign() also calls search_device(),
+		 * but I need the pointer to the device.
+		 */
+		dev = search_device(io_flag, start[j]);
+		if (dev == NULL)
+			continue;
+		/*
+		 * Prevent multiple entries for a device.
+		 */
+		 repeat = 0;
+		 for (k = 0; k < cs_idx; k++) {
+			if (dev == cons_set[k]) {
+				repeat++;
+				break;
+			}
+		 }
+		 if (repeat)
+			continue;
+		/*
+		 * Try assigning the specified device.
+		 * This could screw up the console settings for apps.
+		 */
+		if (console_assign(console, start[j]) < 0)
+			continue;
+#ifdef CONFIG_SERIAL_MULTI
+		/*
+		 * This was taken from common/cmd_nvedit.c.
+		 * This will never work because serial_assign() returns
+		 * 1 upon error, not -1.
+		 * This would almost always return an error anyway because
+		 * serial_assign() expects the name of a serial device, like
+		 * serial_smc, but the user generally only wants to set serial.
+		 */
+		if (serial_assign(start[j]) < 0)
+			continue;
+#endif
+		cons_set[cs_idx++] = dev;
+	}
+	free(console_args);
+	free(start);
+	/* failed to set any console */
+	if (cs_idx == 0) {
+		free(cons_set);
+		return 1;
+	} else {
+		/* Works even if console_devices[console] is NULL. */
+		console_devices[console] =
+			(device_t **)realloc(console_devices[console],
+			cs_idx * sizeof(device_t *));
+		if (console_devices[console] == NULL) {
+			free(cons_set);
+			return 1;
+		}
+		memcpy(console_devices[console], cons_set, cs_idx *
+			sizeof(device_t *));
+
+		cd_count[console] = cs_idx;
+	}
+	free(cons_set);
+	return 0;
+}
+#endif /* CONFIG_CONSOLE_MUX */

doc/README.iomux

@@ -0,0 +1,106 @@
+/*
+ * (C) Copyright 2008
+ * Gary Jennejohn, DENX Software Engineering GmbH <garyj@denx.de>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+U-Boot console multiplexing
+===========================
+
+HOW CONSOLE MULTIPLEXING WORKS
+------------------------------
+
+This functionality is controlled with CONFIG_CONSOLE_MUX in the board
+configuration file.
+
+Two new files, common/iomux.c and include/iomux.h, contain the heart
+(iomux_doenv()) of the environment setting implementation.
+
+iomux_doenv() is called in common/cmd_nvedit.c to handle setenv and in
+common/console.c in console_init_r() during bootup to initialize
+stdio_devices[].
+
+A user can use a comma-separated list of devices to set stdin, stdout
+and stderr.  For example: "setenv stdin serial,nc".  NOTE: No spaces
+are allowed around the comma(s)!
+
+The length of the list is limited by malloc(), since the array used
+is allocated and freed dynamically.
+
+It should be possible to specify any device which console_assign()
+finds acceptable, but the code has only been tested with serial and
+nc.
+
+iomux_doenv() prevents multiple use of the same device, e.g. "setenv
+stdin nc,nc,serial" will discard the second nc.  iomux_doenv() is
+not able to modify the environment, however, so that "pri stdin" still
+shows "nc,nc,serial".
+
+The major change in common/console.c was to modify fgetc() to call
+the iomux_tstc() routine in a for-loop.  iomux_tstc() in turn calls
+the tstc() routine for every registered device, but exits immediately
+when one of them returns true.  fgetc() then calls iomux_getc(),
+which calls the corresponding getc() routine.  fgetc() hangs in
+the for-loop until iomux_tstc() returns true and the input can be
+retrieved.
+
+Thus, a user can type into any device registered for stdin.  No effort
+has been made to demulitplex simultaneous input from multiple stdin
+devices.
+
+fputc() and fputs() have been modified to call iomux_putc() and
+iomux_puts() respectively, which call the corresponding output
+routines for every registered device.
+
+Thus, a user can see the ouput for any device registered for stdout
+or stderr on all devices registered for stdout or stderr.  As an
+example, if stdin=serial,nc and stdout=serial,nc then all output
+for serial, e.g. echos of input on serial, will appear on serial and nc.
+
+Just as with the old console code, this statement is still true:
+If not defined in the environment, the first input device is assigned
+to the 'stdin' file, the first output one to 'stdout' and 'stderr'.
+
+If CONFIG_SYS_CONSOLE_IS_IN_ENV is defined then multiple input/output
+devices can be set at boot time if defined in the environment.
+
+CAVEATS
+-------
+
+Note that common/iomux.c calls console_assign() for every registered
+device as it is discovered.  This means that the environment settings
+for application consoles will be set to the last device in the list.
+
+On a slow machine, such as MPC852T clocked at 66MHz, the overhead associated
+with calling tstc() and then getc() means that copy&paste will normally not
+work, even when stdin=stdout=stderr=serial.
+On a faster machine, such as a sequoia, cut&paste of longer (about 80
+characters) lines works fine when serial is the only device used.
+
+Using nc as a stdin device results in even more overhead because nc_tstc()
+is quite slow.  Even on a sequoia cut&paste does not work on the serial
+interface when nc is added to stdin, although there is no character loss using
+the ethernet interface for input. In this test case stdin=serial,nc and
+stdout=serial.
+
+In addition, the overhead associated with sending to two devices, when one of
+them is nc, also causes problems.  Even on a sequoia cut&paste does not work
+on the serial interface (stdin=serial) when nc is added to stdout (stdout=
+serial,nc).

include/common.h

@@ -678,6 +678,13 @@ void	fputc(int file, const char c);
 int	ftstc(int file);
 int	fgetc(int file);
 
+/*
+ * CONSOLE multiplexing.
+ */
+#ifdef CONFIG_CONSOLE_MUX
+#include <iomux.h>
+#endif
+
 int	pcmcia_init (void);
 
 #ifdef CONFIG_STATUS_LED

include/iomux.h

@@ -0,0 +1,48 @@
+/*
+ * (C) Copyright 2008
+ * Gary Jennejohn, DENX Software Engineering GmbH, garyj@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ *This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef _IO_MUX_H
+#define _IO_MUX_H
+
+#include <devices.h>
+
+/*
+ * Stuff required to support console multiplexing.
+ */
+
+/*
+ * Pointers to devices used for each file type.  Defined in console.c
+ * but storage is allocated in iomux.c.
+ */
+extern device_t **console_devices[MAX_FILES];
+/*
+ * The count of devices assigned to each FILE.  Defined in console.c
+ * and populated in iomux.c.
+ */
+extern int cd_count[MAX_FILES];
+
+int iomux_doenv(const int, const char *);
+void iomux_printdevs(const int);
+device_t *search_device(int, char *);
+
+#endif /* _IO_MUX_H */