#ifndef _IPXE_UART_H
#define _IPXE_UART_H
/** @file
*
* 16550-compatible UART
*
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
/** Transmitter holding register */
#define UART_THR 0x00
/** Receiver buffer register */
#define UART_RBR 0x00
/** Interrupt enable register */
#define UART_IER 0x01
/** FIFO control register */
#define UART_FCR 0x02
#define UART_FCR_FE 0x01 /**< FIFO enable */
/** Line control register */
#define UART_LCR 0x03
#define UART_LCR_WLS0 0x01 /**< Word length select bit 0 */
#define UART_LCR_WLS1 0x02 /**< Word length select bit 1 */
#define UART_LCR_STB 0x04 /**< Number of stop bits */
#define UART_LCR_PEN 0x08 /**< Parity enable */
#define UART_LCR_EPS 0x10 /**< Even parity select */
#define UART_LCR_DLAB 0x80 /**< Divisor latch access bit */
#define UART_LCR_WORD_LEN(x) ( ( (x) - 5 ) << 0 ) /**< Word length */
#define UART_LCR_STOP_BITS(x) ( ( (x) - 1 ) << 2 ) /**< Stop bits */
#define UART_LCR_PARITY(x) ( ( (x) - 0 ) << 3 ) /**< Parity */
/**
* Calculate line control register value
*
* @v word_len Word length (5-8)
* @v parity Parity (0=none, 1=odd, 3=even)
* @v stop_bits Stop bits (1-2)
* @ret lcr Line control register value
*/
#define UART_LCR_WPS( word_len, parity, stop_bits ) \
( UART_LCR_WORD_LEN ( (word_len) ) | \
UART_LCR_PARITY ( (parity) ) | \
UART_LCR_STOP_BITS ( (stop_bits) ) )
/** Default LCR value: 8 data bits, no parity, one stop bit */
#define UART_LCR_8N1 UART_LCR_WPS ( 8, 0, 1 )
/** Modem control register */
#define UART_MCR 0x04
#define UART_MCR_DTR 0x01 /**< Data terminal ready */
#define UART_MCR_RTS 0x02 /**< Request to send */
/** Line status register */
#define UART_LSR 0x05
#define UART_LSR_DR 0x01 /**< Data ready */
#define UART_LSR_THRE 0x20 /**< Transmitter holding register empty */
#define UART_LSR_TEMT 0x40 /**< Transmitter empty */
/** Scratch register */
#define UART_SCR 0x07
/** Divisor latch (least significant byte) */
#define UART_DLL 0x00
/** Divisor latch (most significant byte) */
#define UART_DLM 0x01
/** Maximum baud rate */
#define UART_MAX_BAUD 115200
/** A 16550-compatible UART */
struct uart {
/** I/O port base address */
void *base;
/** Baud rate divisor */
uint16_t divisor;
/** Line control register */
uint8_t lcr;
};
/** Symbolic names for port indexes */
enum uart_port {
COM1 = 1,
COM2 = 2,
COM3 = 3,
COM4 = 4,
};
#include <bits/uart.h>
void uart_write ( struct uart *uart, unsigned int addr, uint8_t data );
uint8_t uart_read ( struct uart *uart, unsigned int addr );
int uart_select ( struct uart *uart, unsigned int port );
/**
* Check if received data is ready
*
* @v uart UART
* @ret ready Data is ready
*/
static inline int uart_data_ready ( struct uart *uart ) {
uint8_t lsr;
lsr = uart_read ( uart, UART_LSR );
return ( lsr & UART_LSR_DR );
}
/**
* Receive data
*
* @v uart UART
* @ret data Data
*/
static inline uint8_t uart_receive ( struct uart *uart ) {
return uart_read ( uart, UART_RBR );
}
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 );
#endif /* _IPXE_UART_H */
