pexpert/i386/pe_serial.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30
  31 /*
  32  * file: pe_serial.c
  33  *       Polled-mode 16x50 UART driver.
  34  */
  35
  36 #include <pexpert/protos.h>
  37 #include <pexpert/pexpert.h>
  38
  39 void    serial_putc(char);
  40 int     serial_getc(void);
  41 int     serial_init(void);
  42
  43 /* standard port addresses */
  44 enum {
  45     COM1_PORT_ADDR = 0x3f8,
  46     COM2_PORT_ADDR = 0x2f8
  47 };
  48
  49 /* UART register offsets */
  50 enum {
  51     UART_RBR = 0,  /* receive buffer Register   (R) */
  52     UART_THR = 0,  /* transmit holding register (W) */
  53     UART_DLL = 0,  /* DLAB = 1, divisor latch (LSB) */
  54     UART_IER = 1,  /* interrupt enable register     */
  55     UART_DLM = 1,  /* DLAB = 1, divisor latch (MSB) */
  56     UART_IIR = 2,  /* interrupt ident register (R)  */
  57     UART_FCR = 2,  /* fifo control register (W)     */
  58     UART_LCR = 3,  /* line control register         */
  59     UART_MCR = 4,  /* modem control register        */
  60     UART_LSR = 5,  /* line status register          */
  61     UART_MSR = 6   /* modem status register         */
  62 };
  63
  64 enum {
  65     UART_LCR_8BITS = 0x03,
  66     UART_LCR_DLAB  = 0x80
  67 };
  68
  69 enum {
  70     UART_MCR_DTR   = 0x01,
  71     UART_MCR_RTS   = 0x02,
  72     UART_MCR_OUT1  = 0x04,
  73     UART_MCR_OUT2  = 0x08,
  74     UART_MCR_LOOP  = 0x10
  75 };
  76
  77 enum {
  78     UART_LSR_DR    = 0x01,
  79     UART_LSR_OE    = 0x02,
  80     UART_LSR_PE    = 0x04,
  81     UART_LSR_FE    = 0x08,
  82     UART_LSR_THRE  = 0x20
  83 };
  84
  85 static unsigned uart_baud_rate = 115200;
  86 #define UART_PORT_ADDR  COM1_PORT_ADDR
  87
  88 #define UART_CLOCK  1843200   /* 1.8432 MHz clock */
  89
  90 #define WRITE(r, v)  outb(UART_PORT_ADDR + UART_##r, v)
  91 #define READ(r)      inb(UART_PORT_ADDR + UART_##r)
  92 #define DELAY(x)     { volatile int _d_; for (_d_ = 0; _d_ < (10000*x); _d_++) ; }
  93
  94 static int uart_initted = 0;   /* 1 if init'ed */
  95
  96 static int
  97 uart_probe( void )
  98 {
  99     /* Verify that the Divisor Register is accessible */
 100
 101     WRITE( LCR, UART_LCR_DLAB );
 102     WRITE( DLL, 0x5a );
 103     if (READ(DLL) != 0x5a) return 0;
 104     WRITE( DLL, 0xa5 );
 105     if (READ(DLL) != 0xa5) return 0;
 106     WRITE( LCR, 0x00 );
 107     return 1;
 108 }
 109
 110 static void
 111 uart_set_baud_rate( unsigned long baud_rate )
 112 {
 113     const unsigned char lcr = READ( LCR );
 114     unsigned long       div;
 115
 116     if (baud_rate == 0) baud_rate = 9600;
 117     div = UART_CLOCK / 16 / baud_rate;
 118     WRITE( LCR, lcr | UART_LCR_DLAB );
 119     WRITE( DLM, (unsigned char)(div >> 8) );
 120     WRITE( DLL, (unsigned char) div );
 121     WRITE( LCR, lcr & ~UART_LCR_DLAB);
 122 }
 123
 124 static void
 125 uart_putc( char c )
 126 {
 127     if (!uart_initted) return;
 128
 129     /* Wait for THR empty */
 130     while ( !(READ(LSR) & UART_LSR_THRE) ) DELAY(1);
 131
 132     WRITE( THR, c );
 133 }
 134
 135 static int
 136 uart_getc( void )
 137 {
 138     /*
 139      * This function returns:
 140      * -1 : no data
 141      * -2 : receiver error
 142      * >0 : character received
 143      */
 144
 145     unsigned char lsr;
 146
 147     if (!uart_initted) return -1;
 148
 149     lsr = READ( LSR );
 150
 151     if ( lsr & (UART_LSR_FE | UART_LSR_PE | UART_LSR_OE) )
 152     {
 153         READ( RBR ); /* discard */
 154         return -2;
 155     }
 156
 157     if ( lsr & UART_LSR_DR )
 158     {
 159         return READ( RBR );
 160     }
 161
 162     return -1;
 163 }
 164
 165 int serial_init( void )
 166 {
 167     unsigned serial_baud_rate = 0;
 168
 169     if ( /*uart_initted ||*/ uart_probe() == 0 ) return 0;
 170
 171     /* Disable hardware interrupts */
 172
 173     WRITE( MCR, 0 );
 174     WRITE( IER, 0 );
 175
 176     /* Disable FIFO's for 16550 devices */
 177
 178     WRITE( FCR, 0 );
 179
 180     /* Set for 8-bit, no parity, DLAB bit cleared */
 181
 182     WRITE( LCR, UART_LCR_8BITS );
 183
 184     /* Set baud rate - use the supplied boot-arg if available */
 185
 186     if (PE_parse_boot_arg("serialbaud", &serial_baud_rate))
 187     {
 188             /* Valid divisor? */
 189             if (!((UART_CLOCK / 16) % serial_baud_rate)) {
 190                     uart_baud_rate = serial_baud_rate;
 191             }
 192     }
 193     uart_set_baud_rate( uart_baud_rate );
 194
 195     /* Assert DTR# and RTS# lines (OUT2?) */
 196
 197     WRITE( MCR, UART_MCR_DTR | UART_MCR_RTS );
 198
 199     /* Clear any garbage in the input buffer */
 200
 201     READ( RBR );
 202
 203     uart_initted = 1;
 204
 205     return 1;
 206 }
 207
 208 void serial_putc( char c )
 209 {
 210     uart_putc(c);
 211     if (c == '\n') uart_putc('\r');
 212 }
 213
 214 int serial_getc( void )
 215 {
 216     return uart_getc();
 217 }