initial checkout from wrc

1 files changed, 694 insertions, 0 deletions

diff --git a/kernel/sio.c b/kernel/sio.c
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+/**
+** @file	sio.c
+**
+** @author	Warren R. Carithers
+**
+** @brief	SIO module
+**
+** For maximum compatibility from semester to semester, this code uses
+** several "stand-in" type names and macros which should be defined
+** in the accompanying "compat.h" header file if they're not part of
+** the baseline system:
+**
+**      standard-sized integer types:  intN_t, uintN_t
+**      other types:  PCBTYPE, QTYPE
+**      scheduler functions:  SCHED, DISPATCH
+**      queue functions:  QCREATE, QLENGTH, QDEQUE
+**      other functions:  SLENGTH
+**      sio read queue:  QNAME
+**
+** Our SIO scheme is very simple:
+**
+**  Input:  We maintain a buffer of incoming characters that haven't
+**      yet been read by processes.  When a character comes in, if
+**      there is no process waiting for it, it goes in the buffer;
+**      otherwise, the first waiting process is awakeneda and it
+**      gets the character.
+**
+**      When a process invokes readch(), if there is a character in
+**      the input buffer, the process gets it; otherwise, it is
+**      blocked until input appears
+**
+**      Communication with system calls is via two routines.
+**      sio_readc() returns the first available character (if
+**      there is one), resetting the input variables if this was
+**      the last character in the buffer.  If there are no
+**      characters in the buffer, sio_read() returns a -1
+**      (presumably so the requesting process can be blocked).
+**
+**      sio_read() copies the contents of the input buffer into
+**      a user-supplied buffer.  It returns the number of characters
+**      copied.  If there are no characters available, return a -1.
+**
+**  Output: We maintain a buffer of outgoing characters that haven't
+**      yet been sent to the device, and an indication of whether
+**      or not we are in the middle of a transmit sequence.  When
+**      an interrupt comes in, if there is another character to
+**      send we copy it to the transmitter buffer; otherwise, we
+**      end the transmit sequence.
+**
+**      Communication with user processes is via three functions.
+**      sio_writec() writes a single character; sio_write()
+**      writes a sized buffer full of characters; sio_puts()
+**      prints a NUL-terminated string.  If we are in the middle
+**      of a transmit sequence, all characters will be added
+**      to the output buffer (from where they will be sent
+**      automatically); otherwise, we send the first character
+**      directly, add the rest of the characters (if there are
+**      any) to the output buffer, and set the "sending" flag
+**      to indicate that we're expecting a transmitter interrupt.
+*/
+
+#define KERNEL_SRC
+
+// this should do all includes required for this OS
+#include <compat.h>
+
+// all other framework includes are next
+#include <x86/uart.h>
+#include <x86/arch.h>
+#include <x86/pic.h>
+
+#include <sio.h>
+#include <lib.h>
+
+/*
+** PRIVATE DEFINITIONS
+*/
+
+#define BUF_SIZE    2048
+
+/*
+** PRIVATE GLOBALS
+*/
+
+	// input character buffer
+static char inbuffer[ BUF_SIZE ];
+static char *inlast;
+static char *innext;
+static uint32_t incount;
+
+	// output character buffer
+static char outbuffer[ BUF_SIZE ];
+static char *outlast;
+static char *outnext;
+static uint32_t outcount;
+
+	// output control flag
+static int sending;
+
+	// interrupt register status
+static uint8_t ier;
+
+/*
+** PUBLIC GLOBAL VARIABLES
+*/
+
+// queue for read-blocked processes
+#ifdef QNAME
+QTYPE QNAME;
+#endif
+
+/*
+** PRIVATE FUNCTIONS
+*/
+
+/**
+** sio_isr(vector,ecode)
+**
+** Interrupt handler for the SIO module.  Handles all pending
+** events (as described by the SIO controller).
+**
+** @param vector   The interrupt vector number for this interrupt
+** @param ecode    The error code associated with this interrupt
+*/
+static void sio_isr( int vector, int ecode ) {
+	int ch;
+
+#if TRACING_SIO_ISR
+	cio_puts( "SIO: int:" );
+#endif
+	//
+	// Must process all pending events; loop until the IRR
+	// says there's nothing else to do.
+	//
+
+	for(;;) {
+
+		// get the "pending event" indicator
+		int iir = inb( UA4_IIR ) & UA4_IIR_INT_PRI_MASK;
+
+		// process this event
+		switch( iir ) {
+
+		case UA4_IIR_LINE_STATUS:
+			// shouldn't happen, but just in case....
+			cio_printf( "** SIO int, LSR = %02x\n", inb(UA4_LSR) );
+			break;
+
+		case UA4_IIR_RX:
+#if TRACING_SIO_ISR
+	cio_puts( " RX" );
+#endif
+			// get the character
+			ch = inb( UA4_RXD );
+			if( ch == '\r' ) {    // map CR to LF
+				ch = '\n';
+			}
+#if TRACING_SIO_ISR
+	cio_printf( " ch %02x", ch );
+#endif
+
+#ifdef QNAME
+			//
+			// If there is a waiting process, this must be
+			// the first input character; give it to that
+			// process and awaken the process.
+			//
+
+			if( !QEMPTY(QNAME) ) {
+				PCBTYPE *pcb;
+
+				QDEQUE( QNAME, pcb );
+				// make sure we got a non-NULL result
+				assert( pcb );
+
+				// return char via arg #2 and count in EAX
+				char *buf = (char *) ARG(pcb,2);
+				*buf = ch & 0xff;
+				RET(pcb) = 1;
+				SCHED( pcb );
+
+			} else {
+#endif /* QNAME */
+
+				//
+				// Nobody waiting - add to the input buffer
+				// if there is room, otherwise just ignore it.
+				//
+
+				if( incount < BUF_SIZE ) {
+					*inlast++ = ch;
+					++incount;
+				}
+
+#ifdef QNAME
+			}
+#endif /* QNAME */
+			break;
+
+		case UA5_IIR_RX_FIFO:
+			// shouldn't happen, but just in case....
+			ch = inb( UA4_RXD );
+			cio_printf( "** SIO FIFO timeout, RXD = %02x\n", ch );
+			break;
+
+		case UA4_IIR_TX:
+#if TRACING_SIO_ISR
+	cio_puts( " TX" );
+#endif
+			// if there is another character, send it
+			if( sending && outcount > 0 ) {
+#if TRACING_SIO_ISR
+	cio_printf( " ch %02x", *outnext );
+#endif
+				outb( UA4_TXD, *outnext );
+				++outnext;
+				// wrap around if necessary
+				if( outnext >= (outbuffer + BUF_SIZE) ) {
+					outnext = outbuffer;
+				}
+				--outcount;
+#if TRACING_SIO_ISR
+	cio_printf( " (outcount %d)", outcount );
+#endif
+			} else {
+#if TRACING_SIO_ISR
+	cio_puts( " EOS" );
+#endif
+				// no more data - reset the output vars
+				outcount = 0;
+				outlast = outnext = outbuffer;
+				sending = 0;
+				// disable TX interrupts
+				sio_disable( SIO_TX );
+			}
+			break;
+
+		case UA4_IIR_NO_INT:
+#if TRACING_SIO_ISR
+	cio_puts( " EOI\n" );
+#endif
+			// nothing to do - tell the PIC we're done
+			outb( PIC1_CMD, PIC_EOI );
+			return;
+
+		case UA4_IIR_MODEM_STATUS:
+			// shouldn't happen, but just in case....
+			cio_printf( "** SIO int, MSR = %02x\n", inb(UA4_MSR) );
+			break;
+
+		default:
+			// uh-oh....
+			sprint( b256, "sio isr: IIR %02x\n", ((uint32_t) iir) & 0xff );
+			PANIC( 0, b256 );
+		}
+	
+	}
+
+	// should never reach this point!
+	assert( false );
+}
+
+/*
+** PUBLIC FUNCTIONS
+*/
+
+/**
+** sio_init()
+**
+** Initialize the UART chip.
+*/
+void sio_init( void ) {
+
+#if TRACING_INIT
+	cio_puts( " Sio" );
+#endif
+
+	/*
+	** Initialize SIO variables.
+	*/
+
+	memclr( (void *) inbuffer, sizeof(inbuffer) );
+	inlast = innext = inbuffer;
+	incount = 0;
+
+	memclr( (void *) outbuffer, sizeof(outbuffer) );
+	outlast = outnext = outbuffer;
+	outcount = 0;
+	sending = 0;
+
+	// queue of read-blocked processes
+	QCREATE( QNAME );
+
+	/*
+	** Next, initialize the UART.
+	**
+	** Initialize the FIFOs
+	**
+	** this is a bizarre little sequence of operations
+	*/
+
+	outb( UA5_FCR, 0x20 );
+	outb( UA5_FCR, UA5_FCR_FIFO_RESET );               // 0x00
+	outb( UA5_FCR, UA5_FCR_FIFO_EN );                  // 0x01
+	outb( UA5_FCR, UA5_FCR_FIFO_EN | UA5_FCR_RXSR );   // 0x03
+	outb( UA5_FCR, UA5_FCR_FIFO_EN | UA5_FCR_RXSR | UA5_FCR_TXSR );  // 0x07
+
+	/*
+	** disable interrupts
+	**
+	** note that we leave them disabled; sio_enable() must be
+	** called to switch them back on
+	*/
+
+	outb( UA4_IER, 0 );
+	ier = 0;
+
+	/*
+	** select the divisor latch registers and set the data rate
+	*/
+
+	outb( UA4_LCR, UA4_LCR_DLAB );
+	outb( UA4_DLL, BAUD_LOW_BYTE( DL_BAUD_9600 ) );
+	outb( UA4_DLM, BAUD_HIGH_BYTE( DL_BAUD_9600 ) );
+
+	/*
+	** deselect the latch registers, by setting the data
+	** characteristics in the LCR
+	*/
+
+	outb( UA4_LCR, UA4_LCR_WLS_8 | UA4_LCR_1_STOP_BIT | UA4_LCR_NO_PARITY );
+	
+	/*
+	** Set the ISEN bit to enable the interrupt request signal,
+	** and the DTR and RTS bits to enable two-way communication.
+	*/
+
+	outb( UA4_MCR, UA4_MCR_ISEN | UA4_MCR_DTR | UA4_MCR_RTS );
+
+	/*
+	** Install our ISR
+	*/
+
+	install_isr( VEC_COM1, sio_isr );
+}
+
+/**
+** sio_enable()
+**
+** Enable SIO interrupts
+**
+** usage:    uint8_t old = sio_enable( uint8_t which )
+**
+** @param which   Bit mask indicating which interrupt(s) to enable
+**
+** @return the prior IER setting
+*/
+uint8_t sio_enable( uint8_t which ) {
+	uint8_t old;
+
+	// remember the current status
+
+	old = ier;
+
+	// figure out what to enable
+
+	if( which & SIO_TX ) {
+		ier |= UA4_IER_TX_IE;
+	}
+
+	if( which & SIO_RX ) {
+		ier |= UA4_IER_RX_IE;
+	}
+
+	// if there was a change, make it
+
+	if( old != ier ) {
+		outb( UA4_IER, ier );
+	}
+
+	// return the prior settings
+
+	return( old );
+}
+
+/**
+** sio_disable()
+**
+** Disable SIO interrupts
+**
+** usage:    uint8_t old = sio_disable( uint8_t which )
+**
+** @param which   Bit mask indicating which interrupt(s) to disable
+**
+** @return the prior IER setting
+*/
+uint8_t sio_disable( uint8_t which ) {
+	uint8_t old;
+
+	// remember the current status
+
+	old = ier;
+
+	// figure out what to disable
+
+	if( which & SIO_TX ) {
+		ier &= ~UA4_IER_TX_IE;
+	}
+
+	if( which & SIO_RX ) {
+		ier &= ~UA4_IER_RX_IE;
+	}
+
+	// if there was a change, make it
+
+	if( old != ier ) {
+		outb( UA4_IER, ier );
+	}
+
+	// return the prior settings
+
+	return( old );
+}
+
+/**
+** sio_inq_length()
+**
+** Get the input queue length
+**
+** usage:    int num = sio_inq_length()
+**
+** @return the count of characters still in the input queue
+*/
+int sio_inq_length( void ) {
+	return( incount );
+}
+
+/**
+** sio_readc()
+**
+** Get the next input character
+**
+** usage:    int ch = sio_readc()
+**
+** @return the next character, or -1 if no character is available
+*/
+int sio_readc( void ) {
+	int ch;
+
+	// assume there is no character available
+	ch = -1;
+
+	// 
+	// If there is a character, return it
+	//
+
+	if( incount > 0 ) {
+
+		// take it out of the input buffer
+		ch = ((int)(*innext++)) & 0xff;
+		--incount;
+
+		// reset the buffer variables if this was the last one
+		if( incount < 1 ) {
+			inlast = innext = inbuffer;
+		}
+
+	}
+
+	return( ch );
+
+}
+
+/**
+** sio_read(buf,length)
+**
+** Read the entire input buffer into a user buffer of a specified size
+**
+** usage:    int num = sio_read( char *buffer, int length )
+**
+** @param buf     The destination buffer
+** @param length  Length of the buffer
+**
+** @return the number of bytes copied, or 0 if no characters were available
+*/
+
+int sio_read( char *buf, int length ) {
+	char *ptr = buf;
+	int copied = 0;
+
+	// if there are no characters, just return 0
+
+	if( incount < 1 ) {
+		return( 0 );
+	}
+
+	//
+	// We have characters.  Copy as many of them into the user
+	// buffer as will fit.
+	//
+
+	while( incount > 0 && copied < length ) {
+		*ptr++ = *innext++ & 0xff;
+		if( innext > (inbuffer + BUF_SIZE) ) {
+			innext = inbuffer;
+		}
+		--incount;
+		++copied;
+	}
+
+	// reset the input buffer if necessary
+
+	if( incount < 1 ) {
+		inlast = innext = inbuffer;
+	}
+
+	// return the copy count
+
+	return( copied );
+}
+
+
+/**
+** sio_writec( ch )
+**
+** Write a character to the serial output
+**
+** usage:    sio_writec( int ch )
+**
+** @param ch   Character to be written (in the low-order 8 bits)
+*/
+void sio_writec( int ch ){
+
+
+	//
+	// Must do LF -> CRLF mapping
+	//
+
+	if( ch == '\n' ) {
+		sio_writec( '\r' );
+	}
+
+	//
+	// If we're currently transmitting, just add this to the buffer
+	//
+
+	if( sending ) {
+		*outlast++ = ch;
+		++outcount;
+		return;
+	}
+
+	//
+	// Not sending - must prime the pump
+	//
+
+	sending = 1;
+	outb( UA4_TXD, ch );
+
+	// Also must enable transmitter interrupts
+
+	sio_enable( SIO_TX );
+
+}
+
+/**
+** sio_write( buffer, length )
+**
+** Write a buffer of characters to the serial output
+**
+** usage:    int num = sio_write( const char *buffer, int length )
+**
+** @param buffer   Buffer containing characters to write
+** @param length   Number of characters to write
+**
+** @return the number of characters copied into the SIO output buffer
+*/
+int sio_write( const char *buffer, int length ) {
+	int first = *buffer;
+	const char *ptr = buffer;
+	int copied = 0;
+
+	//
+	// If we are currently sending, we want to append all
+	// the characters to the output buffer; else, we want
+	// to append all but the first character, and then use
+	// sio_writec() to send the first one out.
+	//
+
+	if( !sending ) {
+		ptr += 1;
+		copied++;
+	}
+
+	while( copied < length && outcount < BUF_SIZE ) {
+		*outlast++ = *ptr++;
+		// wrap around if necessary
+		if( outlast >= (outbuffer + BUF_SIZE) ) {
+			outlast = outbuffer;
+		}
+		++outcount;
+		++copied;
+	}
+
+	//
+	// We use sio_writec() to send out the first character,
+	// as it will correctly set all the other necessary
+	// variables for us.
+	//
+
+	if( !sending ) {
+		sio_writec( first );
+	}
+
+	// Return the transfer count
+
+
+	return( copied );
+
+}
+
+/**
+** sio_puts( buf )
+**
+** Write a NUL-terminated buffer of characters to the serial output
+**
+** usage:    int num = sio_puts( const char *buffer )
+**
+** @param buffer  The buffer containing a NUL-terminated string
+**
+** @return the count of bytes transferred
+*/
+int sio_puts( const char *buffer ) {
+	int n;  // must be outside the loop so we can return it
+
+	n = SLENGTH( buffer );
+	sio_write( buffer, n );
+
+	return( n );
+}
+
+/**
+** sio_dump( full )
+**
+** dump the contents of the SIO buffers to the console
+**
+** usage:    sio_dump(true) or sio_dump(false)
+**
+** @param full   Boolean indicating whether or not a "full" dump
+**               is being requested (which includes the contents
+**               of the queues)
+*/
+
+void sio_dump( bool_t full ) {
+	int n;
+	char *ptr;
+
+	// dump basic info into the status region
+
+	cio_printf_at( 48, 0,
+		"SIO: IER %02x (%c%c%c) in %d ot %d",
+			((uint32_t)ier) & 0xff, sending ? '*' : '.',
+			(ier & UA4_IER_TX_IE) ? 'T' : 't',
+			(ier & UA4_IER_RX_IE) ? 'R' : 'r',
+			incount, outcount );
+
+	// if we're not doing a full dump, stop now
+
+	if( !full ) {
+		return;
+	}
+
+	// also want the queue contents, but we'll
+	// dump them into the scrolling region
+
+	if( incount ) {
+		cio_puts( "SIO input queue: \"" );
+		ptr = innext; 
+		for( n = 0; n < incount; ++n ) {
+			put_char_or_code( *ptr++ );
+		}
+		cio_puts( "\"\n" );
+	}
+
+	if( outcount ) {
+		cio_puts( "SIO output queue: \"" );
+		cio_puts( " ot: \"" );
+		ptr = outnext; 
+		for( n = 0; n < outcount; ++n )  {
+			put_char_or_code( *ptr++ );
+		}
+		cio_puts( "\"\n" );
+	}
+}