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authorStefan Hajnoczi <stefanha@gmail.com>2008-08-29 15:08:26 +0100
committerStefan Hajnoczi <stefanha@gmail.com>2008-08-29 15:08:26 +0100
commit77950e64a458e753900ff4ff6119bea15d1a4533 (patch)
tree3d00561537edc658061392b2e8400f21ececdd85 /com32/gdbstub/serial.c
parent968a89b1417d24e3247c96950b434de1971b0d4e (diff)
downloadsyslinux.git-77950e64a458e753900ff4ff6119bea15d1a4533.tar.gz
syslinux.git-77950e64a458e753900ff4ff6119bea15d1a4533.tar.xz
syslinux.git-77950e64a458e753900ff4ff6119bea15d1a4533.zip
Add GDB stub
Diffstat (limited to 'com32/gdbstub/serial.c')
-rw-r--r--com32/gdbstub/serial.c190
1 files changed, 190 insertions, 0 deletions
diff --git a/com32/gdbstub/serial.c b/com32/gdbstub/serial.c
new file mode 100644
index 00000000..1c4d4b6f
--- /dev/null
+++ b/com32/gdbstub/serial.c
@@ -0,0 +1,190 @@
+/*
+ * The serial port interface routines implement a simple polled i/o
+ * interface to a standard serial port. Due to the space restrictions
+ * for the boot blocks, no BIOS support is used (since BIOS requires
+ * expensive real/protected mode switches), instead the rudimentary
+ * BIOS support is duplicated here.
+ *
+ * The base address and speed for the i/o port are passed from the
+ * Makefile in the COMCONSOLE and CONSPEED preprocessor macros. The
+ * line control parameters are currently hard-coded to 8 bits, no
+ * parity, 1 stop bit (8N1). This can be changed in init_serial().
+ */
+
+#include <stddef.h>
+#include <sys/io.h>
+#include "serial.h"
+
+/* Set default values if none specified */
+
+#ifndef COMCONSOLE
+#define COMCONSOLE 0x3f8
+#endif
+
+#ifndef COMSPEED
+#define COMSPEED 9600
+#endif
+
+#ifndef COMDATA
+#define COMDATA 8
+#endif
+
+#ifndef COMPARITY
+#define COMPARITY 0
+#endif
+
+#ifndef COMSTOP
+#define COMSTOP 1
+#endif
+
+#undef UART_BASE
+#define UART_BASE ( COMCONSOLE )
+
+#undef UART_BAUD
+#define UART_BAUD ( COMSPEED )
+
+#if ((115200%UART_BAUD) != 0)
+#error Bad ttys0 baud rate
+#endif
+
+#define COMBRD (115200/UART_BAUD)
+
+/* Line Control Settings */
+#define UART_LCS ( ( ( (COMDATA) - 5 ) << 0 ) | \
+ ( ( (COMPARITY) ) << 3 ) | \
+ ( ( (COMSTOP) - 1 ) << 2 ) )
+
+/* Data */
+#define UART_RBR 0x00
+#define UART_TBR 0x00
+
+/* Control */
+#define UART_IER 0x01
+#define UART_IIR 0x02
+#define UART_FCR 0x02
+#define UART_LCR 0x03
+#define UART_MCR 0x04
+#define UART_DLL 0x00
+#define UART_DLM 0x01
+
+/* Status */
+#define UART_LSR 0x05
+#define UART_LSR_TEMPT 0x40 /* Transmitter empty */
+#define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
+#define UART_LSR_BI 0x10 /* Break interrupt indicator */
+#define UART_LSR_FE 0x08 /* Frame error indicator */
+#define UART_LSR_PE 0x04 /* Parity error indicator */
+#define UART_LSR_OE 0x02 /* Overrun error indicator */
+#define UART_LSR_DR 0x01 /* Receiver data ready */
+
+#define UART_MSR 0x06
+#define UART_SCR 0x07
+
+#define uart_readb(addr) inb(addr)
+#define uart_writeb(val,addr) outb((val),(addr))
+
+/*
+ * void serial_putc(int ch);
+ * Write character `ch' to port UART_BASE.
+ */
+void serial_putc ( int ch ) {
+ int status;
+ for (;;) {
+ status = uart_readb(UART_BASE + UART_LSR);
+ if (status & UART_LSR_THRE) {
+ /* TX buffer emtpy */
+ uart_writeb(ch, UART_BASE + UART_TBR);
+ break;
+ }
+ }
+}
+
+/*
+ * int serial_getc(void);
+ * Read a character from port UART_BASE.
+ */
+int serial_getc ( void ) {
+ int status;
+ int ch;
+ do {
+ status = uart_readb(UART_BASE + UART_LSR);
+ } while((status & 1) == 0);
+ ch = uart_readb(UART_BASE + UART_RBR); /* fetch (first) character */
+ ch &= 0x7f; /* remove any parity bits we get */
+ if (ch == 0x7f) { /* Make DEL... look like BS */
+ ch = 0x08;
+ }
+ return ch;
+}
+
+/*
+ * int serial_init(void);
+ * Initialize port UART_BASE to speed COMSPEED, line settings 8N1.
+ */
+void serial_init ( void ) {
+ int status;
+ int divisor, lcs;
+
+ divisor = COMBRD;
+ lcs = UART_LCS;
+
+
+#ifdef COMPRESERVE
+ lcs = uart_readb(UART_BASE + UART_LCR) & 0x7f;
+ uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
+ divisor = (uart_readb(UART_BASE + UART_DLM) << 8) | uart_readb(UART_BASE + UART_DLL);
+ uart_writeb(lcs, UART_BASE + UART_LCR);
+#endif
+
+ /* Set Baud Rate Divisor to COMSPEED, and test to see if the
+ * serial port appears to be present.
+ */
+ uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
+ uart_writeb(0xaa, UART_BASE + UART_DLL);
+ if (uart_readb(UART_BASE + UART_DLL) != 0xaa) {
+ goto out;
+ }
+ uart_writeb(0x55, UART_BASE + UART_DLL);
+ if (uart_readb(UART_BASE + UART_DLL) != 0x55) {
+ goto out;
+ }
+ uart_writeb(divisor & 0xff, UART_BASE + UART_DLL);
+ if (uart_readb(UART_BASE + UART_DLL) != (divisor & 0xff)) {
+ goto out;
+ }
+ uart_writeb(0xaa, UART_BASE + UART_DLM);
+ if (uart_readb(UART_BASE + UART_DLM) != 0xaa) {
+ goto out;
+ }
+ uart_writeb(0x55, UART_BASE + UART_DLM);
+ if (uart_readb(UART_BASE + UART_DLM) != 0x55) {
+ goto out;
+ }
+ uart_writeb((divisor >> 8) & 0xff, UART_BASE + UART_DLM);
+ if (uart_readb(UART_BASE + UART_DLM) != ((divisor >> 8) & 0xff)) {
+ goto out;
+ }
+ uart_writeb(lcs, UART_BASE + UART_LCR);
+
+ /* disable interrupts */
+ uart_writeb(0x0, UART_BASE + UART_IER);
+
+ /* disable fifo's */
+ uart_writeb(0x00, UART_BASE + UART_FCR);
+
+ /* Set clear to send, so flow control works... */
+ uart_writeb((1<<1), UART_BASE + UART_MCR);
+
+
+ /* Flush the input buffer. */
+ do {
+ /* rx buffer reg
+ * throw away (unconditionally the first time)
+ */
+ (void) uart_readb(UART_BASE + UART_RBR);
+ /* line status reg */
+ status = uart_readb(UART_BASE + UART_LSR);
+ } while(status & UART_LSR_DR);
+ out:
+ return;
+}