Add a "comconsole_speed" loader variable that can be used to change

the serial console speed (i386 and amd64 only). If the previous
stage boot loader requested a serial console (RB_SERIAL or RB_MULTIPLE)
then the default speed is determined from the current serial port
speed. Otherwise it is set to 9600 or the value of BOOT_COMCONSOLE_SPEED
at compile time.

This makes it possible to set the serial port speed once in
/boot.config and the setting will propagate to boot2, loader and
the kernel serial console.

sys/boot/common/loader.8

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 27, 2005
+.Dd August 18, 2005
 .Dt LOADER 8
 .Os
 .Sh NAME
@@ -392,6 +392,19 @@ by the kernel during the boot phase.
 List of semicolon-separated search path for bootable kernels.
 The default is
 .Dq Li kernel .
+.It Va comconsole_speed
+Defines the speed of the serial console (i386 and amd64 only).
+If the previous boot stage indicated that a serial console is in use
+then this variable is initialized to the current speed of the console
+serial port.
+Otherwise it is set to 9600 unless this was overridden using the
+.Va BOOT_COMCONSOLE_SPEED
+variable when
+.Nm
+was compiled.
+Changes to the
+.Va comconsole_speed
+variable take effect immediately.
 .It Va console
 Defines the current console or consoles.
 Multiple consoles may be specified.

sys/boot/forth/loader.conf

@@ -47,6 +47,7 @@ loader_color="NO"		# Set this to YES to enable splash screen colors
 				# allowed to interrupt autoboot process and
 				# escape to the loader prompt
 #beastie_disable="NO"		# Turn the beastie boot menu on and off
+#comconsole_speed="9600"	# Set the current serial console speed
 #console="vidconsole"		# A comma separated list of console(s)
 #currdev="disk1s1a"		# Set the current device
 module_path="/boot/modules"	# Set the module search path

sys/boot/forth/loader.conf.5

@@ -23,7 +23,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\" $FreeBSD$
-.Dd November 7, 2004
+.Dd August 18, 2005
 .Dt LOADER.CONF 5
 .Os
 .Sh NAME
@@ -164,6 +164,18 @@ a bitmap will be loaded to be displayed on screen while booting.
 .Pq Dq Pa /boot/splash.bmp
 Name of the bitmap to be loaded.
 Any other name can be used.
+.It Va comconsole_speed
+.Po Dq 9600
+or the value of the
+.Va BOOT_COMCONSOLE_SPEED
+variable when
+.Xr loader 8
+was compiled
+.Pc .
+Sets the speed of the serial console.
+If the previous boot loader stage specified that a serial console
+is in use then the default speed is determined from the current
+serial port speed setting.
 .It Va console
 .Pq Dq vidconsole
 .Dq comconsole

sys/boot/i386/libi386/comconsole.c

@@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
 #define COMC_FMT	0x3		/* 8N1 */
 #define COMC_TXWAIT	0x40000		/* transmit timeout */
 #define COMC_BPS(x)	(115200 / (x))	/* speed to DLAB divisor */
+#define COMC_DIV2BPS(x)	(115200 / (x))	/* DLAB divisor to speed */
 
 #ifndef	COMPORT
 #define COMPORT		0x3f8
@@ -47,9 +48,15 @@ static void	comc_probe(struct console *cp);
 static int	comc_init(int arg);
 static void	comc_putchar(int c);
 static int	comc_getchar(void);
+static int	comc_getspeed(void);
 static int	comc_ischar(void);
+static int	comc_parsespeed(const char *string);
+static void	comc_setup(int speed);
+static int	comc_speed_set(struct env_var *ev, int flags,
+		    const void *value);
 
 static int	comc_started;
+static int	comc_curspeed;
 
 struct console comconsole = {
     "comconsole",
@@ -65,8 +72,36 @@ struct console comconsole = {
 static void
 comc_probe(struct console *cp)
 {
+    char speedbuf[16];
+    char *cons, *speedenv;
+    int speed;
+
     /* XXX check the BIOS equipment list? */
     cp->c_flags |= (C_PRESENTIN | C_PRESENTOUT);
+
+    if (comc_curspeed == 0) {
+	comc_curspeed = COMSPEED;
+	/*
+	 * Assume that the speed was set by an earlier boot loader if
+	 * comconsole is already the preferred console.
+	 */
+	cons = getenv("console");
+	if ((cons != NULL && strcmp(cons, comconsole.c_name) == 0) ||
+	    getenv("boot_multicons") != NULL) {
+		comc_curspeed = comc_getspeed();
+	}
+	speedenv = getenv("comconsole_speed");
+	if (speedenv != NULL) {
+	    speed = comc_parsespeed(speedenv);
+	    if (speed > 0)
+		comc_curspeed = speed;
+	}
+
+	sprintf(speedbuf, "%d", comc_curspeed);
+	unsetenv("comconsole_speed");
+	env_setenv("comconsole_speed", EV_VOLATILE, speedbuf, comc_speed_set,
+	    env_nounset);
+    }
 }
 
 static int
@@ -76,15 +111,7 @@ comc_init(int arg)
 	return 0;
     comc_started = 1;
 
-    outb(COMPORT + com_cfcr, CFCR_DLAB | COMC_FMT);
-    outb(COMPORT + com_dlbl, COMC_BPS(COMSPEED) & 0xff);
-    outb(COMPORT + com_dlbh, COMC_BPS(COMSPEED) >> 8);
-    outb(COMPORT + com_cfcr, COMC_FMT);
-    outb(COMPORT + com_mcr, MCR_RTS | MCR_DTR);
-
-    do
-        inb(COMPORT + com_data);
-    while (inb(COMPORT + com_lsr) & LSR_RXRDY);
+    comc_setup(comc_curspeed);
 
     return(0);
 }
@@ -112,3 +139,75 @@ comc_ischar(void)
 {
     return(inb(COMPORT + com_lsr) & LSR_RXRDY);
 }
+
+static int
+comc_speed_set(struct env_var *ev, int flags, const void *value)
+{
+    int speed;
+
+    if (value == NULL || (speed = comc_parsespeed(value)) <= 0) {
+	printf("Invalid speed\n");
+	return (CMD_ERROR);
+    }
+
+    if (comc_started && comc_curspeed != speed)
+	comc_setup(speed);
+
+    env_setenv(ev->ev_name, flags | EV_NOHOOK, value, NULL, NULL);
+
+    return (CMD_OK);
+}
+
+static void
+comc_setup(int speed)
+{
+
+    comc_curspeed = speed;
+
+    outb(COMPORT + com_cfcr, CFCR_DLAB | COMC_FMT);
+    outb(COMPORT + com_dlbl, COMC_BPS(speed) & 0xff);
+    outb(COMPORT + com_dlbh, COMC_BPS(speed) >> 8);
+    outb(COMPORT + com_cfcr, COMC_FMT);
+    outb(COMPORT + com_mcr, MCR_RTS | MCR_DTR);
+
+    do
+        inb(COMPORT + com_data);
+    while (inb(COMPORT + com_lsr) & LSR_RXRDY);
+}
+
+static int
+comc_parsespeed(const char *speedstr)
+{
+    char *p;
+    int speed;
+
+    speed = strtol(speedstr, &p, 0);
+    if (p == speedstr || *p != '\0' || speed <= 0)
+	return (-1);
+
+    return (speed);
+}
+
+static int
+comc_getspeed(void)
+{
+	u_int	divisor;
+	u_char	dlbh;
+	u_char	dlbl;
+	u_char	cfcr;
+
+	cfcr = inb(COMPORT + com_cfcr);
+	outb(COMPORT + com_cfcr, CFCR_DLAB | cfcr);
+
+	dlbl = inb(COMPORT + com_dlbl);
+	dlbh = inb(COMPORT + com_dlbh);
+
+	outb(COMPORT + com_cfcr, cfcr);
+
+	divisor = dlbh << 8 | dlbl;
+
+	/* XXX there should be more sanity checking. */
+	if (divisor == 0)
+		return (COMSPEED);
+	return (COMC_DIV2BPS(divisor));
+}