[uart] Remove ability to use frame formats other than 8n1

In the context of serial consoles, the use of any frame formats other
than the standard 8 data bits, no parity, and one stop bit is so rare
as to be nonexistent.

Remove the almost certainly unused support for custom frame formats.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/serial.h

@@ -16,15 +16,12 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define	COMCONSOLE	COM1		/* I/O port address */
 
 /* Keep settings from a previous user of the serial port (e.g. lilo or
- * LinuxBIOS), ignoring COMSPEED, COMDATA, COMPARITY and COMSTOP.
+ * LinuxBIOS), ignoring COMSPEED.
  */
 #undef	COMPRESERVE
 
 #ifndef COMPRESERVE
 #define	COMSPEED	115200		/* Baud rate */
-#define	COMDATA		8		/* Data bits */
-#define	COMPARITY	0		/* Parity: 0=None, 1=Odd, 2=Even */
-#define	COMSTOP		1		/* Stop bits */
 #endif
 
 /* Early UART configuration (for bare metal prefix debugging only) */

src/core/gdbserial.c

@@ -46,13 +46,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define GDBSERIAL_BAUD COMSPEED
 #endif
 
-/* UART line control register value */
-#ifdef COMPRESERVE
-#define GDBSERIAL_LCR 0
-#else
-#define GDBSERIAL_LCR UART_LCR_WPS ( COMDATA, COMPARITY, COMSTOP )
-#endif
-
 /** GDB serial UART */
 static struct uart gdbserial_uart;
 
@@ -90,7 +83,7 @@ static int gdbserial_init ( int argc, char **argv ) {
 		return 1;
 	}
 
-	if ( ! gdbserial_configure ( port, GDBSERIAL_BAUD, GDBSERIAL_LCR ) ) {
+	if ( ! gdbserial_configure ( port, GDBSERIAL_BAUD ) ) {
 		printf ( "serial: unable to configure\n" );
 		return 1;
 	}
@@ -106,13 +99,13 @@ struct gdb_transport serial_gdb_transport __gdb_transport = {
 };
 
 struct gdb_transport * gdbserial_configure ( unsigned int port,
-					     unsigned int baud, uint8_t lcr ) {
+					     unsigned int baud ) {
 	int rc;
 
 	if ( ( rc = uart_select ( &gdbserial_uart, port ) ) != 0 )
 		return NULL;
 
-	if ( ( rc = uart_init ( &gdbserial_uart, baud, lcr ) ) != 0 )
+	if ( ( rc = uart_init ( &gdbserial_uart, baud ) ) != 0 )
 		return NULL;
 
 	return &serial_gdb_transport;

src/core/serial.c

@@ -58,13 +58,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define CONSOLE_BAUD COMSPEED
 #endif
 
-/* UART line control register value */
-#ifdef COMPRESERVE
-#define CONSOLE_LCR 0
-#else
-#define CONSOLE_LCR UART_LCR_WPS ( COMDATA, COMPARITY, COMSTOP )
-#endif
-
 /** Serial console UART */
 struct uart serial_console;
 
@@ -149,10 +142,9 @@ static void serial_init ( void ) {
 	}
 
 	/* Initialise UART */
-	if ( ( rc = uart_init ( &serial_console, CONSOLE_BAUD,
-				CONSOLE_LCR ) ) != 0 ) {
-		DBG ( "Could not initialise UART %d baud %d LCR %#02x: %s\n",
-		      CONSOLE_PORT, CONSOLE_BAUD, CONSOLE_LCR, strerror ( rc ));
+	if ( ( rc = uart_init ( &serial_console, CONSOLE_BAUD ) ) != 0 ) {
+		DBG ( "Could not initialise UART %d baud %d: %s\n",
+		      CONSOLE_PORT, CONSOLE_BAUD, strerror ( rc ) );
 		return;
 	}
 }

src/core/uart.c

@@ -107,10 +107,9 @@ int uart_exists ( struct uart *uart ) {
  *
  * @v uart		UART
  * @v baud		Baud rate, or zero to leave unchanged
- * @v lcr		Line control register value, or zero to leave unchanged
  * @ret rc		Return status code
  */
-int uart_init ( struct uart *uart, unsigned int baud, uint8_t lcr ) {
+int uart_init ( struct uart *uart, unsigned int baud ) {
 	uint8_t dlm;
 	uint8_t dll;
 	int rc;
@@ -120,10 +119,7 @@ int uart_init ( struct uart *uart, unsigned int baud, uint8_t lcr ) {
 		return rc;
 
 	/* Configure divisor and line control register, if applicable */
-	if ( ! lcr )
-		lcr = uart_read ( uart, UART_LCR );
-	uart->lcr = lcr;
-	uart_write ( uart, UART_LCR, ( lcr | UART_LCR_DLAB ) );
+	uart_write ( uart, UART_LCR, ( UART_LCR_8N1 | UART_LCR_DLAB ) );
 	if ( baud ) {
 		uart->divisor = ( UART_MAX_BAUD / baud );
 		dlm = ( ( uart->divisor >> 8 ) & 0xff );
@@ -135,7 +131,7 @@ int uart_init ( struct uart *uart, unsigned int baud, uint8_t lcr ) {
 		dll = uart_read ( uart, UART_DLL );
 		uart->divisor = ( ( dlm << 8 ) | dll );
 	}
-	uart_write ( uart, UART_LCR, ( lcr & ~UART_LCR_DLAB ) );
+	uart_write ( uart, UART_LCR, UART_LCR_8N1 );
 
 	/* Disable interrupts */
 	uart_write ( uart, UART_IER, 0 );

src/include/ipxe/gdbserial.h

@@ -9,12 +9,9 @@
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
-#include <stdint.h>
-
 struct gdb_transport;
 
 extern struct gdb_transport * gdbserial_configure ( unsigned int port,
-						    unsigned int baud,
-						    uint8_t lcr );
+						    unsigned int baud );
 
 #endif /* _IPXE_GDBSERIAL_H */

src/include/ipxe/uart.h

@@ -82,8 +82,6 @@ struct uart {
 	void *base;
 	/** Baud rate divisor */
 	uint16_t divisor;
-	/** Line control register */
-	uint8_t lcr;
 };
 
 /** Symbolic names for port indexes */
@@ -127,6 +125,6 @@ static inline uint8_t uart_receive ( struct uart *uart ) {
 extern void uart_transmit ( struct uart *uart, uint8_t data );
 extern void uart_flush ( struct uart *uart );
 extern int uart_exists ( struct uart *uart );
-extern int uart_init ( struct uart *uart, unsigned int baud, uint8_t lcr );
+extern int uart_init ( struct uart *uart, unsigned int baud );
 
 #endif /* _IPXE_UART_H */