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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().
- */
-
- #include "stddef.h"
- #include "console.h"
- #include "init.h"
- #include "io.h"
- #include "timer.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
-
- static struct console_driver serial_console;
-
- /*
- * void serial_putc(int ch);
- * Write character `ch' to port UART_BASE.
- */
- static 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.
- */
- static 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.
- */
- static 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;
-
- 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)
- */
- uart_readb(UART_BASE + UART_RBR);
- /* line status reg */
- status = uart_readb(UART_BASE + UART_LSR);
- } while(status & UART_LSR_DR);
- serial_console.disabled = 0;
- out:
- return;
- }
-
- /*
- * void serial_fini(void);
- * Cleanup our use of the serial port, in particular flush the
- * output buffer so we don't accidentially loose characters.
- */
- static void serial_fini ( void ) {
- int i, status;
- if (serial_console.disabled) {
- /* no serial interface */
- return;
- }
- /* 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 */
- }
-
- static struct console_driver serial_console __console_driver = {
- .putchar = serial_putc,
- .getchar = serial_getc,
- .iskey = serial_ischar,
- .disabled = 1,
- };
-
- INIT_FN ( INIT_CONSOLE, serial_init, NULL, serial_fini );
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