add 'terminal program' functionality

This patch adds a 'cu' like serial terminal command to u-boot
using which you can access other serial ports from the system console.

OpenMoko uses this in their Neo1973 phones to get access to the GSM
Modem and GPS chip from the bootloader.

Signed-off-by: Harald Welte <laforge@openmoko.org>

common/Makefile

@@ -86,6 +86,7 @@ COBJS-$(CONFIG_CMD_REISER) += cmd_reiser.o
 COBJS-y += cmd_sata.o
 COBJS-$(CONFIG_CMD_SCSI) += cmd_scsi.o
 COBJS-$(CONFIG_CMD_SPI) += cmd_spi.o
+COBJS-$(CONFIG_CMD_TERMINAL) += cmd_terminal.o
 COBJS-$(CONFIG_CMD_UNIVERSE) += cmd_universe.o
 COBJS-$(CONFIG_CMD_USB) += cmd_usb.o
 COBJS-y += cmd_vfd.o

common/cmd_terminal.c

@@ -0,0 +1,102 @@
+/*
+ * (C) Copyright 2007 OpenMoko, Inc.
+ * Written by Harald Welte <laforge@openmoko.org>
+ *
+ * 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
+ */
+
+/*
+ * Boot support
+ */
+#include <common.h>
+#include <command.h>
+#include <devices.h>
+
+#if defined(CONFIG_CMD_TERMINAL)
+
+int do_terminal(cmd_tbl_t * cmd, int flag, int argc, char *argv[])
+{
+	int i, l;
+	int last_tilde = 0;
+	device_t *dev = NULL;
+
+	if (argc < 1)
+		return -1;
+
+	/* Scan for selected output/input device */
+	for (i = 1; i <= ListNumItems (devlist); i++) {
+		device_t *tmp = ListGetPtrToItem (devlist, i);
+		if (!strcmp(tmp->name, argv[1])) {
+			dev = tmp;
+			break;
+		}
+	}
+	if (!dev)
+		return -1;
+
+	serial_reinit_all();
+	printf("Entering terminal mode for port %s\n", dev->name);
+	puts("Use '~.' to leave the terminal and get back to u-boot\n");
+
+	while (1) {
+		int c;
+
+		/* read from console and display on serial port */
+		if (stdio_devices[0]->tstc()) {
+			c = stdio_devices[0]->getc();
+			if (last_tilde == 1) {
+				if (c == '.') {
+					putc(c);
+					putc('\n');
+					break;
+				} else {
+					last_tilde = 0;
+					/* write the delayed tilde */
+					dev->putc('~');
+					/* fall-through to print current
+					 * character */
+				}
+			}
+			if (c == '~') {
+				last_tilde = 1;
+				puts("[u-boot]");
+				putc(c);
+			}
+			dev->putc(c);
+		}
+
+		/* read from serial port and display on console */
+		if (dev->tstc()) {
+			c = dev->getc();
+			putc(c);
+		}
+	}
+	return 0;
+}
+
+
+/***************************************************/
+
+U_BOOT_CMD(
+	terminal,	3,	1,	do_terminal,
+	"terminal - start terminal emulator\n",
+	""
+);
+
+#endif /* CONFIG_CMD_TERMINAL */

include/config_cmd_all.h

@@ -73,6 +73,7 @@
 #define CONFIG_CMD_SETGETDCR	/* DCR support on 4xx		*/
 #define CONFIG_CMD_SNTP		/* SNTP support			*/
 #define CONFIG_CMD_SPI		/* SPI utility			*/
+#define CONFIG_CMD_TERMINAL	/* built-in Serial Terminal	*/
 #define CONFIG_CMD_UNIVERSE	/* Tundra Universe Support	*/
 #define CONFIG_CMD_USB		/* USB Support			*/
 #define CONFIG_CMD_VFD		/* VFD support (TRAB)		*/