src/core/serial.c

   1 /*
   2  * The serial port interface routines implement a simple polled i/o
   3  * interface to a standard serial port.  Due to the space restrictions
   4  * for the boot blocks, no BIOS support is used (since BIOS requires
   5  * expensive real/protected mode switches), instead the rudimentary
   6  * BIOS support is duplicated here.
   7  *
   8  * The base address and speed for the i/o port are passed from the
   9  * Makefile in the COMCONSOLE and CONSPEED preprocessor macros.  The
  10  * line control parameters are currently hard-coded to 8 bits, no
  11  * parity, 1 stop bit (8N1).  This can be changed in init_serial().
  12  */
  13
  14 FILE_LICENCE ( GPL2_OR_LATER );
  15
  16 #include "stddef.h"
  17 #include <gpxe/init.h>
  18 #include <gpxe/io.h>
  19 #include <unistd.h>
  20 #include <gpxe/serial.h>
  21 #include "config/serial.h"
  22
  23 /* Set default values if none specified */
  24
  25 #ifndef COMCONSOLE
  26 #define COMCONSOLE      0x3f8
  27 #endif
  28
  29 #ifndef COMSPEED
  30 #define COMSPEED        9600
  31 #endif
  32
  33 #ifndef COMDATA
  34 #define COMDATA         8
  35 #endif
  36
  37 #ifndef COMPARITY
  38 #define COMPARITY       0
  39 #endif
  40
  41 #ifndef COMSTOP
  42 #define COMSTOP         1
  43 #endif
  44
  45 #undef UART_BASE
  46 #define UART_BASE ( COMCONSOLE )
  47
  48 #undef UART_BAUD
  49 #define UART_BAUD ( COMSPEED )
  50
  51 #if ((115200%UART_BAUD) != 0)
  52 #error Bad ttys0 baud rate
  53 #endif
  54
  55 #define COMBRD (115200/UART_BAUD)
  56
  57 /* Line Control Settings */
  58 #define UART_LCS ( ( ( (COMDATA) - 5 )  << 0 ) | \
  59                    ( ( (COMPARITY) )    << 3 ) | \
  60                    ( ( (COMSTOP) - 1 )  << 2 ) )
  61
  62 /* Data */
  63 #define UART_RBR 0x00
  64 #define UART_TBR 0x00
  65
  66 /* Control */
  67 #define UART_IER 0x01
  68 #define UART_IIR 0x02
  69 #define UART_FCR 0x02
  70 #define UART_LCR 0x03
  71 #define UART_MCR 0x04
  72 #define UART_DLL 0x00
  73 #define UART_DLM 0x01
  74
  75 /* Status */
  76 #define UART_LSR 0x05
  77 #define  UART_LSR_TEMPT 0x40    /* Transmitter empty */
  78 #define  UART_LSR_THRE  0x20    /* Transmit-hold-register empty */
  79 #define  UART_LSR_BI    0x10    /* Break interrupt indicator */
  80 #define  UART_LSR_FE    0x08    /* Frame error indicator */
  81 #define  UART_LSR_PE    0x04    /* Parity error indicator */
  82 #define  UART_LSR_OE    0x02    /* Overrun error indicator */
  83 #define  UART_LSR_DR    0x01    /* Receiver data ready */
  84
  85 #define UART_MSR 0x06
  86 #define UART_SCR 0x07
  87
  88 #if defined(UART_MEM)
  89 #define uart_readb(addr) readb((addr))
  90 #define uart_writeb(val,addr) writeb((val),(addr))
  91 #else
  92 #define uart_readb(addr) inb((addr))
  93 #define uart_writeb(val,addr) outb((val),(addr))
  94 #endif
  95
  96 /*
  97  * void serial_putc(int ch);
  98  *      Write character `ch' to port UART_BASE.
  99  */
 100 void serial_putc ( int ch ) {
 101         int i;
 102         int status;
 103         i = 1000; /* timeout */
 104         while(--i > 0) {
 105                 status = uart_readb(UART_BASE + UART_LSR);
 106                 if (status & UART_LSR_THRE) {
 107                         /* TX buffer emtpy */
 108                         uart_writeb(ch, UART_BASE + UART_TBR);
 109                         break;
 110                 }
 111                 mdelay(2);
 112         }
 113 }
 114
 115 /*
 116  * int serial_getc(void);
 117  *      Read a character from port UART_BASE.
 118  */
 119 int serial_getc ( void ) {
 120         int status;
 121         int ch;
 122         do {
 123                 status = uart_readb(UART_BASE + UART_LSR);
 124         } while((status & 1) == 0);
 125         ch = uart_readb(UART_BASE + UART_RBR);  /* fetch (first) character */
 126         ch &= 0x7f;                             /* remove any parity bits we get */
 127         if (ch == 0x7f) {                       /* Make DEL... look like BS */
 128                 ch = 0x08;
 129         }
 130         return ch;
 131 }
 132
 133 /*
 134  * int serial_ischar(void);
 135  *       If there is a character in the input buffer of port UART_BASE,
 136  *       return nonzero; otherwise return 0.
 137  */
 138 int serial_ischar ( void ) {
 139         int status;
 140         status = uart_readb(UART_BASE + UART_LSR);      /* line status reg; */
 141         return status & 1;              /* rx char available */
 142 }
 143
 144 /*
 145  * int serial_init(void);
 146  *      Initialize port UART_BASE to speed COMSPEED, line settings 8N1.
 147  */
 148 static void serial_init ( void ) {
 149         int status;
 150         int divisor, lcs;
 151
 152         DBG ( "Serial port %#x initialising\n", UART_BASE );
 153
 154         divisor = COMBRD;
 155         lcs = UART_LCS;
 156
 157
 158 #ifdef COMPRESERVE
 159         lcs = uart_readb(UART_BASE + UART_LCR) & 0x7f;
 160         uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
 161         divisor = (uart_readb(UART_BASE + UART_DLM) << 8) | uart_readb(UART_BASE + UART_DLL);
 162         uart_writeb(lcs, UART_BASE + UART_LCR);
 163 #endif
 164
 165         /* Set Baud Rate Divisor to COMSPEED, and test to see if the
 166          * serial port appears to be present.
 167          */
 168         uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
 169         uart_writeb(0xaa, UART_BASE + UART_DLL);
 170         if (uart_readb(UART_BASE + UART_DLL) != 0xaa) {
 171                 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
 172                 goto out;
 173         }
 174         uart_writeb(0x55, UART_BASE + UART_DLL);
 175         if (uart_readb(UART_BASE + UART_DLL) != 0x55) {
 176                 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
 177                 goto out;
 178         }
 179         uart_writeb(divisor & 0xff, UART_BASE + UART_DLL);
 180         if (uart_readb(UART_BASE + UART_DLL) != (divisor & 0xff)) {
 181                 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
 182                 goto out;
 183         }
 184         uart_writeb(0xaa, UART_BASE + UART_DLM);
 185         if (uart_readb(UART_BASE + UART_DLM) != 0xaa) {
 186                 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
 187                 goto out;
 188         }
 189         uart_writeb(0x55, UART_BASE + UART_DLM);
 190         if (uart_readb(UART_BASE + UART_DLM) != 0x55) {
 191                 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
 192                 goto out;
 193         }
 194         uart_writeb((divisor >> 8) & 0xff, UART_BASE + UART_DLM);
 195         if (uart_readb(UART_BASE + UART_DLM) != ((divisor >> 8) & 0xff)) {
 196                 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
 197                 goto out;
 198         }
 199         uart_writeb(lcs, UART_BASE + UART_LCR);
 200
 201         /* disable interrupts */
 202         uart_writeb(0x0, UART_BASE + UART_IER);
 203
 204         /* disable fifo's */
 205         uart_writeb(0x00, UART_BASE + UART_FCR);
 206
 207         /* Set clear to send, so flow control works... */
 208         uart_writeb((1<<1), UART_BASE + UART_MCR);
 209
 210
 211         /* Flush the input buffer. */
 212         do {
 213                 /* rx buffer reg
 214                  * throw away (unconditionally the first time)
 215                  */
 216                 (void) uart_readb(UART_BASE + UART_RBR);
 217                 /* line status reg */
 218                 status = uart_readb(UART_BASE + UART_LSR);
 219         } while(status & UART_LSR_DR);
 220  out:
 221         return;
 222 }
 223
 224 /*
 225  * void serial_fini(void);
 226  *      Cleanup our use of the serial port, in particular flush the
 227  *      output buffer so we don't accidentially lose characters.
 228  */
 229 static void serial_fini ( int flags __unused ) {
 230         int i, status;
 231         /* Flush the output buffer to avoid dropping characters,
 232          * if we are reinitializing the serial port.
 233          */
 234         i = 10000; /* timeout */
 235         do {
 236                 status = uart_readb(UART_BASE + UART_LSR);
 237         } while((--i > 0) && !(status & UART_LSR_TEMPT));
 238         /* Don't mark it as disabled; it's still usable */
 239 }
 240
 241 /**
 242  * Serial driver initialisation function
 243  *
 244  * Initialise serial port early on so that it is available to capture
 245  * early debug messages.
 246  */
 247 struct init_fn serial_init_fn __init_fn ( INIT_SERIAL ) = {
 248         .initialise = serial_init,
 249 };
 250
 251 /** Serial driver startup function */
 252 struct startup_fn serial_startup_fn __startup_fn ( STARTUP_EARLY ) = {
 253         .shutdown = serial_fini,
 254 };