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/*
* 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().
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include "stddef.h"
#include <gpxe/init.h>
#include <gpxe/io.h>
#include <unistd.h>
#include <gpxe/serial.h>
#include "config/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
#if defined(UART_MEM)
#define uart_readb(addr) readb((addr))
#define uart_writeb(val,addr) writeb((val),(addr))
#else
#define uart_readb(addr) inb((addr))
#define uart_writeb(val,addr) outb((val),(addr))
#endif
/*
* void serial_putc(int ch);
* Write character `ch' to port UART_BASE.
*/
void serial_putc ( int ch ) {
int i;
int status;
i = 1000; /* timeout */
while(--i > 0) {
status = uart_readb(UART_BASE + UART_LSR);
if (status & UART_LSR_THRE) {
/* TX buffer emtpy */
uart_writeb(ch, UART_BASE + UART_TBR);
break;
}
mdelay(2);
}
}
/*
* 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_ischar(void);
* If there is a character in the input buffer of port UART_BASE,
* return nonzero; otherwise return 0.
*/
int serial_ischar ( void ) {
int status;
status = uart_readb(UART_BASE + UART_LSR); /* line status reg; */
return status & 1; /* rx char available */
}
/*
* int serial_init(void);
* Initialize port UART_BASE to speed COMSPEED, line settings 8N1.
*/
static void serial_init ( void ) {
int status;
int divisor, lcs;
DBG ( "Serial port %#x initialising\n", UART_BASE );
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) {
DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
goto out;
}
uart_writeb(0x55, UART_BASE + UART_DLL);
if (uart_readb(UART_BASE + UART_DLL) != 0x55) {
DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
goto out;
}
uart_writeb(divisor & 0xff, UART_BASE + UART_DLL);
if (uart_readb(UART_BASE + UART_DLL) != (divisor & 0xff)) {
DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
goto out;
}
uart_writeb(0xaa, UART_BASE + UART_DLM);
if (uart_readb(UART_BASE + UART_DLM) != 0xaa) {
DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
goto out;
}
uart_writeb(0x55, UART_BASE + UART_DLM);
if (uart_readb(UART_BASE + UART_DLM) != 0x55) {
DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
goto out;
}
uart_writeb((divisor >> 8) & 0xff, UART_BASE + UART_DLM);
if (uart_readb(UART_BASE + UART_DLM) != ((divisor >> 8) & 0xff)) {
DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
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;
}
/*
* void serial_fini(void);
* Cleanup our use of the serial port, in particular flush the
* output buffer so we don't accidentially lose characters.
*/
static void serial_fini ( int flags __unused ) {
int i, status;
/* Flush the output buffer to avoid dropping characters,
* if we are reinitializing the serial port.
*/
i = 10000; /* timeout */
do {
status = uart_readb(UART_BASE + UART_LSR);
} while((--i > 0) && !(status & UART_LSR_TEMPT));
/* Don't mark it as disabled; it's still usable */
}
/**
* Serial driver initialisation function
*
* Initialise serial port early on so that it is available to capture
* early debug messages.
*/
struct init_fn serial_init_fn __init_fn ( INIT_SERIAL ) = {
.initialise = serial_init,
};
/** Serial driver startup function */
struct startup_fn serial_startup_fn __startup_fn ( STARTUP_EARLY ) = {
.shutdown = serial_fini,
};
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