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[serial] Add general abstraction of a 16550-compatible UART 

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2015-06-29 08:39:58 +01:00
parent edf74df4ab
commit 611c9e39da
6 changed files with 371 additions and 0 deletions
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62
src/arch/x86/core/x86_uart.c Normal file
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/*
* Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** @file
*
* 16550-compatible UART
*
*/
#include <errno.h>
#include <ipxe/uart.h>
/** UART port bases */
static uint16_t uart_base[] = {
[COM1] = 0x3f8,
[COM2] = 0x2f8,
[COM3] = 0x3e8,
[COM4] = 0x2e8,
};
/**
* Select UART port
*
* @v uart UART
* @v port Port number, or 0 to disable
* @ret rc Return status code
*/
int uart_select ( struct uart *uart, unsigned int port ) {
/* Clear UART base */
uart->base = NULL;
/* Set new UART base */
if ( port < ( sizeof ( uart_base ) / sizeof ( uart_base[0] ) ) ) {
uart->base = ( ( void * ) ( intptr_t ) uart_base[port] );
return 0;
} else {
return -ENODEV;
}
}

1
src/arch/x86/include/bits/errfile.h
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@ -48,6 +48,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#define ERRFILE_timer_bios ( ERRFILE_ARCH | ERRFILE_DRIVER | 0x00010000 )
#define ERRFILE_hvm ( ERRFILE_ARCH | ERRFILE_DRIVER | 0x00020000 )
#define ERRFILE_hyperv ( ERRFILE_ARCH | ERRFILE_DRIVER | 0x00030000 )
#define ERRFILE_x86_uart ( ERRFILE_ARCH | ERRFILE_DRIVER | 0x00040000 )
#define ERRFILE_cpuid_cmd ( ERRFILE_ARCH | ERRFILE_OTHER | 0x00000000 )
#define ERRFILE_cpuid_settings ( ERRFILE_ARCH | ERRFILE_OTHER | 0x00010000 )

41
src/arch/x86/include/bits/uart.h Normal file
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#ifndef _BITS_UART_H
#define _BITS_UART_H
/** @file
*
* 16550-compatible UART
*
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <ipxe/io.h>
/**
* Write to UART register
*
* @v uart UART
* @v addr Register address
* @v data Data
*/
static inline __attribute__ (( always_inline )) void
uart_write ( struct uart *uart, unsigned int addr, uint8_t data ) {
outb ( data, ( uart->base + addr ) );
}
/**
* Read from UART register
*
* @v uart UART
* @v addr Register address
* @ret data Data
*/
static inline __attribute__ (( always_inline )) uint8_t
uart_read ( struct uart *uart, unsigned int addr ) {
return inb ( uart->base + addr );
}
extern int uart_select ( struct uart *uart, unsigned int port );
#endif /* _BITS_UART_H */

135
src/core/uart.c Normal file
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/*
* Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** @file
*
* 16550-compatible UART
*
*/
#include <unistd.h>
#include <errno.h>
#include <ipxe/uart.h>
/** Timeout for transmit holding register to become empty */
#define UART_THRE_TIMEOUT_MS 100
/** Timeout for transmitter to become empty */
#define UART_TEMT_TIMEOUT_MS 1000
/**
* Transmit data
*
* @v uart UART
* @v data Data
*/
void uart_transmit ( struct uart *uart, uint8_t data ) {
unsigned int i;
uint8_t lsr;
/* Wait for transmitter holding register to become empty */
for ( i = 0 ; i < UART_THRE_TIMEOUT_MS ; i++ ) {
lsr = uart_read ( uart, UART_LSR );
if ( lsr & UART_LSR_THRE )
break;
mdelay ( 1 );
}
/* Transmit data (even if we timed out) */
uart_write ( uart, UART_THR, data );
}
/**
* Flush data
*
* @v uart UART
*/
void uart_flush ( struct uart *uart ) {
unsigned int i;
uint8_t lsr;
/* Wait for transmitter and receiver to become empty */
for ( i = 0 ; i < UART_TEMT_TIMEOUT_MS ; i++ ) {
uart_read ( uart, UART_RBR );
lsr = uart_read ( uart, UART_LSR );
if ( ( lsr & UART_LSR_TEMT ) && ! ( lsr & UART_LSR_DR ) )
break;
}
}
/**
* Initialise 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 ) {
uint8_t dlm;
uint8_t dll;
/* Check for existence of UART */
if ( ! uart->base )
return -ENODEV;
uart_write ( uart, UART_SCR, 0x18 );
if ( uart_read ( uart, UART_SCR ) != 0x18 )
return -ENODEV;
uart_write ( uart, UART_SCR, 0xae );
if ( uart_read ( uart, UART_SCR ) != 0xae )
return -ENODEV;
/* 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 ) );
if ( baud ) {
uart->divisor = ( UART_MAX_BAUD / baud );
dlm = ( ( uart->divisor >> 8 ) & 0xff );
dll = ( ( uart->divisor >> 0 ) & 0xff );
uart_write ( uart, UART_DLM, dlm );
uart_write ( uart, UART_DLL, dll );
} else {
dlm = uart_read ( uart, UART_DLM );
dll = uart_read ( uart, UART_DLL );
uart->divisor = ( ( dlm << 8 ) | dll );
}
uart_write ( uart, UART_LCR, ( lcr & ~UART_LCR_DLAB ) );
/* Disable interrupts */
uart_write ( uart, UART_IER, 0 );
/* Enable FIFOs */
uart_write ( uart, UART_FCR, UART_FCR_FE );
/* Assert DTR and RTS */
uart_write ( uart, UART_MCR, ( UART_MCR_DTR | UART_MCR_RTS ) );
/* Flush any stale data */
uart_flush ( uart );
return 0;
}

1
src/include/ipxe/errfile.h
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@ -89,6 +89,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#define ERRFILE_i2c_bit ( ERRFILE_DRIVER | 0x00120000 )
#define ERRFILE_spi_bit ( ERRFILE_DRIVER | 0x00130000 )
#define ERRFILE_nvsvpd ( ERRFILE_DRIVER | 0x00140000 )
#define ERRFILE_uart ( ERRFILE_DRIVER | 0x00150000 )
#define ERRFILE_3c509 ( ERRFILE_DRIVER | 0x00200000 )
#define ERRFILE_bnx2 ( ERRFILE_DRIVER | 0x00210000 )

131
src/include/ipxe/uart.h Normal file
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#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_init ( struct uart *uart, unsigned int baud, uint8_t lcr );
#endif /* _IPXE_UART_H */