Add cttybaud boot monitor variable to control speed of serial console (combine with ctty 0)

common/include/minix/const.h

@@ -158,6 +158,7 @@
 #define INVAL_GID	       ((gid_t) -1)	/* invalid gid value */
 
 #define SERVARNAME		"cttyline"
+#define SERBAUDVARNAME		"cttybaud"
 
 /* Bits for the system property flags in boot image processes. */
 #define PROC_FULLVM    0x100    /* VM sets and manages full pagetable */

kernel/arch/i386/arch_system.c

@@ -53,6 +53,9 @@ FORWARD _PROTOTYPE( void ser_debug, (int c));
 #ifdef CONFIG_SMP
 FORWARD _PROTOTYPE( void ser_dump_proc_cpu, (void));
 #endif
+#if !CONFIG_OXPCIE
+FORWARD _PROTOTYPE( void ser_init, (void));
+#endif
 
 PUBLIC __dead void arch_monitor(void)
 {
@@ -371,6 +374,10 @@ PUBLIC void arch_init(void)
 	tss_init(0, get_k_stack_top(0));
 #endif
 
+#if !CONFIG_OXPCIE
+	ser_init();
+#endif
+
 	acpi_init();
 
 #if defined(CONFIG_APIC) && !defined(CONFIG_SMP)
@@ -719,3 +726,30 @@ PUBLIC void fpu_sigcontext(struct proc *pr, struct sigframe *fr, struct sigconte
 				  * FPE_INTDIV */
 	}
 }
+
+#if !CONFIG_OXPCIE
+PRIVATE void ser_init(void)
+{
+	unsigned char lcr;
+	unsigned divisor;
+
+	/* keep BIOS settings if cttybaud is not set */
+	if (serial_debug_baud <= 0) return;
+
+	/* set DLAB to make baud accessible */
+	lcr = LCR_8BIT | LCR_1STOP | LCR_NPAR;
+	outb(COM1_LCR, lcr | LCR_DLAB);
+
+	/* set baud rate */
+	divisor = UART_BASE_FREQ / serial_debug_baud;
+	if (divisor < 1) divisor = 1;
+	if (divisor > 65535) divisor = 65535;
+	
+	outb(COM1_DLL, divisor & 0xff);
+	outb(COM1_DLM, (divisor >> 8) & 0xff);
+
+	/* clear DLAB */
+	outb(COM1_LCR, lcr);
+}
+#endif
+

kernel/arch/i386/serial.h

@@ -2,19 +2,37 @@
 #ifndef _KERN_SERIAL_H
 #define _KERN_SERIAL_H 1
 
-#define THRREG  0
-#define RBRREG  0
-#define FICRREG 2
-#define LSRREG  5
-#define LCRREG  3
+#define THRREG  0	/* transmitter holding, write-only, DLAB must be clear */
+#define RBRREG  0	/* receiver buffer, read-only, DLAB must be clear */
+#define DLLREG  0	/* divisor latch LSB, read/write, DLAB must be set */
+#define DLMREG  1	/* divisor latch MSB, read/write, DLAB must be set */
+#define FICRREG 2	/* FIFO control, write-only */
+#define LCRREG  3	/* line control, read/write */
+#define LSRREG  5	/* line status, read-only */
 #define SPRREG  7
 
-#define COM1_BASE       0x3F8
-#define COM1_THR        (COM1_BASE + THRREG)
-#define COM1_RBR (COM1_BASE + RBRREG)
-#define COM1_LSR        (COM1_BASE + LSRREG)
+#define COM1_BASE	0x3F8
+#define COM1_THR	(COM1_BASE + THRREG)
+#define COM1_RBR	(COM1_BASE + RBRREG)
+#define COM1_DLL	(COM1_BASE + DLLREG)
+#define COM1_DLM	(COM1_BASE + DLMREG)
+#define COM1_LCR	(COM1_BASE + LCRREG)
+#define         LCR_5BIT	0x00 /* 5 bits per data word */
+#define         LCR_6BIT	0x01 /* 6 bits per data word */
+#define         LCR_7BIT	0x02 /* 7 bits per data word */
+#define         LCR_8BIT	0x03 /* 8 bits per data word */
+#define         LCR_1STOP	0x00 /* 1/1.5 stop bits */
+#define         LCR_2STOP	0x04 /* 2 stop bits */
+#define         LCR_NPAR	0x00 /* no parity */
+#define         LCR_OPAR	0x08 /* odd parity */
+#define         LCR_EPAR	0x18 /* even parity */
+#define         LCR_BREAK	0x40 /* enable break */
+#define         LCR_DLAB	0x80 /* access DLAB registers */
+#define COM1_LSR	(COM1_BASE + LSRREG)
 #define         LSR_DR          0x01
 #define         LSR_THRE        0x20
 #define         LCR_DLA         0x80
 
+#define UART_BASE_FREQ	115200U	
+
 #endif

kernel/glo.h

@@ -42,6 +42,7 @@ EXTERN u32_t system_hz;				/* HZ value */
 EXTERN reg_t mon_sp;			/* boot monitor stack */
 EXTERN int mon_return;			/* true if we can return to monitor */
 EXTERN int do_serial_debug;
+EXTERN int serial_debug_baud;
 EXTERN time_t boottime;
 EXTERN char params_buffer[512];		/* boot monitor parameters */
 EXTERN int minix_panicing;

kernel/start.c

@@ -83,10 +83,16 @@ PUBLIC void cstart(
 	system_hz = atoi(value);
   if(!value || system_hz < 2 || system_hz > 50000)	/* sanity check */
 	system_hz = DEFAULT_HZ;
+
+  /* Intitialize serial debugging */
   value = env_get(SERVARNAME);
-  if(value && atoi(value) == 0)
+  if(value && atoi(value) == 0) {
 	do_serial_debug=1;
 
+  	value = env_get(SERBAUDVARNAME);
+  	if (value) serial_debug_baud = atoi(value);
+  }
+
 #ifdef CONFIG_APIC
   value = env_get("no_apic");
   if(value)