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 #include "stddef.h"
  15 #include <gpxe/init.h>
  16 #include <gpxe/io.h>
  17 #include <unistd.h>
  18 #include <gpxe/serial.h>
  19 #include "config/serial.h"
  20
  21 /* Set default values if none specified */
  22
  23 #ifndef COMCONSOLE
  24 #define COMCONSOLE      0x3f8
  25 #endif
  26
  27 #ifndef COMSPEED
  28 #define COMSPEED        9600
  29 #endif
  30
  31 #ifndef COMDATA
  32 #define COMDATA         8
  33 #endif
  34
  35 #ifndef COMPARITY
  36 #define COMPARITY       0
  37 #endif
  38
  39 #ifndef COMSTOP
  40 #define COMSTOP         1
  41 #endif
  42
  43 #undef UART_BASE
  44 #define UART_BASE ( COMCONSOLE )
  45
  46 #undef UART_BAUD
  47 #define UART_BAUD ( COMSPEED )
  48
  49 #if ((115200%UART_BAUD) != 0)
  50 #error Bad ttys0 baud rate
  51 #endif
  52
  53 #define COMBRD (115200/UART_BAUD)
  54
  55 /* Line Control Settings */
  56 #define UART_LCS ( ( ( (COMDATA) - 5 )  << 0 ) | \
  57                    ( ( (COMPARITY) )    << 3 ) | \
  58                    ( ( (COMSTOP) - 1 )  << 2 ) )
  59
  60 /* Data */
  61 #define UART_RBR 0x00
  62 #define UART_TBR 0x00
  63
  64 /* Control */
  65 #define UART_IER 0x01
  66 #define UART_IIR 0x02
  67 #define UART_FCR 0x02
  68 #define UART_LCR 0x03
  69 #define UART_MCR 0x04
  70 #define UART_DLL 0x00
  71 #define UART_DLM 0x01
  72
  73 /* Status */
  74 #define UART_LSR 0x05
  75 #define  UART_LSR_TEMPT 0x40    /* Transmitter empty */
  76 #define  UART_LSR_THRE  0x20    /* Transmit-hold-register empty */
  77 #define  UART_LSR_BI    0x10    /* Break interrupt indicator */
  78 #define  UART_LSR_FE    0x08    /* Frame error indicator */
  79 #define  UART_LSR_PE    0x04    /* Parity error indicator */
  80 #define  UART_LSR_OE    0x02    /* Overrun error indicator */
  81 #define  UART_LSR_DR    0x01    /* Receiver data ready */
  82
  83 #define UART_MSR 0x06
  84 #define UART_SCR 0x07
  85
  86 #if defined(UART_MEM)
  87 #define uart_readb(addr) readb((addr))
  88 #define uart_writeb(val,addr) writeb((val),(addr))
  89 #else
  90 #define uart_readb(addr) inb((addr))
  91 #define uart_writeb(val,addr) outb((val),(addr))
  92 #endif
  93
  94 /*
  95  * void serial_putc(int ch);
  96  *      Write character `ch' to port UART_BASE.
  97  */
  98 void serial_putc ( int ch ) {
  99         int i;
 100         int status;
 101         i = 1000; /* timeout */
 102         while(--i > 0) {
 103                 status = uart_readb(UART_BASE + UART_LSR);
 104                 if (status & UART_LSR_THRE) {
 105                         /* TX buffer emtpy */
 106                         uart_writeb(ch, UART_BASE + UART_TBR);
 107                         break;
 108                 }
 109                 mdelay(2);
 110         }
 111 }
 112
 113 /*
 114  * int serial_getc(void);
 115  *      Read a character from port UART_BASE.
 116  */
 117 int serial_getc ( void ) {
 118         int status;
 119         int ch;
 120         do {
 121                 status = uart_readb(UART_BASE + UART_LSR);
 122         } while((status & 1) == 0);
 123         ch = uart_readb(UART_BASE + UART_RBR);  /* fetch (first) character */
 124         ch &= 0x7f;                             /* remove any parity bits we get */
 125         if (ch == 0x7f) {                       /* Make DEL... look like BS */
 126                 ch = 0x08;
 127         }
 128         return ch;
 129 }
 130
 131 /*
 132  * int serial_ischar(void);
 133  *       If there is a character in the input buffer of port UART_BASE,
 134  *       return nonzero; otherwise return 0.
 135  */
 136 int serial_ischar ( void ) {
 137         int status;
 138         status = uart_readb(UART_BASE + UART_LSR);      /* line status reg; */
 139         return status & 1;              /* rx char available */
 140 }
 141
 142 /*
 143  * int serial_init(void);
 144  *      Initialize port UART_BASE to speed COMSPEED, line settings 8N1.
 145  */
 146 static void serial_init ( void ) {
 147         int status;
 148         int divisor, lcs;
 149
 150         DBG ( "Serial port %#x initialising\n", UART_BASE );
 151
 152         divisor = COMBRD;
 153         lcs = UART_LCS;
 154
 155
 156 #ifdef COMPRESERVE
 157         lcs = uart_readb(UART_BASE + UART_LCR) & 0x7f;
 158         uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
 159         divisor = (uart_readb(UART_BASE + UART_DLM) << 8) | uart_readb(UART_BASE + UART_DLL);
 160         uart_writeb(lcs, UART_BASE + UART_LCR);
 161 #endif
 162
 163         /* Set Baud Rate Divisor to COMSPEED, and test to see if the
 164          * serial port appears to be present.
 165          */
 166         uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
 167         uart_writeb(0xaa, UART_BASE + UART_DLL);
 168         if (uart_readb(UART_BASE + UART_DLL) != 0xaa) {
 169                 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
 170                 goto out;
 171         }
 172         uart_writeb(0x55, UART_BASE + UART_DLL);
 173         if (uart_readb(UART_BASE + UART_DLL) != 0x55) {
 174                 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
 175                 goto out;
 176         }
 177         uart_writeb(divisor & 0xff, UART_BASE + UART_DLL);
 178         if (uart_readb(UART_BASE + UART_DLL) != (divisor & 0xff)) {
 179                 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
 180                 goto out;
 181         }
 182         uart_writeb(0xaa, UART_BASE + UART_DLM);
 183         if (uart_readb(UART_BASE + UART_DLM) != 0xaa) {
 184                 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
 185                 goto out;
 186         }
 187         uart_writeb(0x55, UART_BASE + UART_DLM);
 188         if (uart_readb(UART_BASE + UART_DLM) != 0x55) {
 189                 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
 190                 goto out;
 191         }
 192         uart_writeb((divisor >> 8) & 0xff, UART_BASE + UART_DLM);
 193         if (uart_readb(UART_BASE + UART_DLM) != ((divisor >> 8) & 0xff)) {
 194                 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
 195                 goto out;
 196         }
 197         uart_writeb(lcs, UART_BASE + UART_LCR);
 198
 199         /* disable interrupts */
 200         uart_writeb(0x0, UART_BASE + UART_IER);
 201
 202         /* disable fifo's */
 203         uart_writeb(0x00, UART_BASE + UART_FCR);
 204
 205         /* Set clear to send, so flow control works... */
 206         uart_writeb((1<<1), UART_BASE + UART_MCR);
 207
 208
 209         /* Flush the input buffer. */
 210         do {
 211                 /* rx buffer reg
 212                  * throw away (unconditionally the first time)
 213                  */
 214                 (void) uart_readb(UART_BASE + UART_RBR);
 215                 /* line status reg */
 216                 status = uart_readb(UART_BASE + UART_LSR);
 217         } while(status & UART_LSR_DR);
 218  out:
 219         return;
 220 }
 221
 222 /*
 223  * void serial_fini(void);
 224  *      Cleanup our use of the serial port, in particular flush the
 225  *      output buffer so we don't accidentially lose characters.
 226  */
 227 static void serial_fini ( int flags __unused ) {
 228         int i, status;
 229         /* Flush the output buffer to avoid dropping characters,
 230          * if we are reinitializing the serial port.
 231          */
 232         i = 10000; /* timeout */
 233         do {
 234                 status = uart_readb(UART_BASE + UART_LSR);
 235         } while((--i > 0) && !(status & UART_LSR_TEMPT));
 236         /* Don't mark it as disabled; it's still usable */
 237 }
 238
 239 /**
 240  * Serial driver initialisation function
 241  *
 242  * Initialise serial port early on so that it is available to capture
 243  * early debug messages.
 244  */
 245 struct init_fn serial_init_fn __init_fn ( INIT_SERIAL ) = {
 246         .initialise = serial_init,
 247 };
 248
 249 /** Serial driver startup function */
 250 struct startup_fn serial_startup_fn __startup_fn ( STARTUP_EARLY ) = {
 251         .shutdown = serial_fini,
 252 };