lpc214x_lowputc.s

這是一個實時嵌入式作業系統 實作了MCS51 ARM等MCU

/**************************************************************************
 * lpc214x/lpc214X_lowputc.S
 *
 *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <[e-mail]>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 **************************************************************************/

/**************************************************************************
 * Included Files
 **************************************************************************/

#include <nuttx/config.h>
#include "up_internal.h"
#include "up_arch.h"
#include "lpc214x_uart.h"

/**************************************************************************
 * Private Definitions
 **************************************************************************/

#if defined(CONFIG_UART0_SERIAL_CONSOLE)
#  define LPC214X_UART_BASE    LPC214X_UART0_BASE
#  define LPC214X_UART_PINSEL  LPC214X_UART0_PINSEL
#  define LPC214X_UART_PINMASK LPC214X_UART0_PINMASK
#  define LPC214X_UART_BAUD    CONFIG_UART0_BAUD
#  define LPC214X_UART_BITS    CONFIG_UART0_BITS
#  define LPC214X_UART_PARITY  CONFIG_UART0_PARITY
#  define LPC214X_UART_2STOP   CONFIG_UART0_2STOP
#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
#  define LPC214X_UART_BASE    LPC214X_UART1_BASE
#  define LPC214X_UART_PINSEL  LPC214X_UART1_PINSEL
#  define LPC214X_UART_PINMASK LPC214X_UART1_PINMASK
#  define LPC214X_UART_BAUD    CONFIG_UART1_BAUD
#  define LPC214X_UART_BITS    CONFIG_UART1_BITS
#  define LPC214X_UART_PARITY  CONFIG_UART1_PARITY
#  define LPC214X_UART_2STOP   CONFIG_UART1_2STOP
#else
#  error "No CONFIG_UARTn_SERIAL_CONSOLE Setting"
#endif

#if LPC214X_UART_BITS == 5
#  define LPC214X_LCR_CHAR LPC214X_LCR_CHAR_5
#elif LPC214X_UART_BITS == 6
#  define LPC214X_LCR_CHAR LPC214X_LCR_CHAR_6
#elif LPC214X_UART_BITS == 7
#  define LPC214X_LCR_CHAR LPC214X_LCR_CHAR_7
#elif LPC214X_UART_BITS == 8
#  define LPC214X_LCR_CHAR LPC214X_LCR_CHAR_8
#else
#  error "No CONFIG_UARTn_BITS Setting"
#endif

#if LPC214X_UART_PARITY == 0
#  define LPC214X_LCR_PAR LPC214X_LCR_PAR_NONE
#elif LPC214X_UART_PARITY == 1
#  define LPC214X_LCR_PAR LPC214X_LCR_PAR_ODD
#elif LPC214X_UART_PARITY == 2
#  define LPC214X_LCR_PAR LPC214X_LCR_PAR_EVEN
#elif LPC214X_UART_PARITY == 3
#  define LPC214X_LCR_PAR LPC214X_LCR_PAR_MARK
#elif LPC214X_UART_PARITY == 4
#  define LPC214X_LCR_PAR LPC214X_LCR_PAR_SPACE
#else
#  error "No CONFIG_UARTn_PARITY Setting"
#endif

#if LPC214X_UART_2STOP != 0
#  define LPC214X_LCR_STOP LPC214X_LCR_STOP_2
#else
#  define LPC214X_LCR_STOP LPC214X_LCR_STOP_1
#endif

#define LPC214X_LCR_VALUE (LPC214X_LCR_CHAR | LPC214X_LCR_PAR | LPC214X_LCR_STOP)

/**************************************************************************
 * Private Types
 **************************************************************************/

/**************************************************************************
 * Private Function Prototypes
 **************************************************************************/

/**************************************************************************
 * Global Variables
 **************************************************************************/

/**************************************************************************
 * Private Variables
 **************************************************************************/

/**************************************************************************
 * Private Functions
 **************************************************************************/

/**************************************************************************
 * Public Functions
 **************************************************************************/

/**************************************************************************
 * Name: up_lowputc
 **************************************************************************/

/* This assembly language version has the advantage that it can does not
 * require a C stack and uses only r0-r1.  Hence it can be used during
 * early boot phases.
 */

	.text
	.global	up_lowputc
	.type	up_lowputc, function
up_lowputc:
	/* On entry, r0 holds the character to be printed */

	ldr	r1, =LPC214X_UART_BASE
	strb	r0, [r1, #LPC214X_UART_THR_OFFSET]

	/* Wait for the byte to be transferred */

1:	ldr	r0, [r1, #LPC214X_UART_LSR_OFFSET]
	ands	r0, #LPC214X_LSR_TEMT  /* Transmitter empty */
	beq	1b

	/* And return */

	mov     pc, lr
	.size	up_lowputc, . - up_lowputc

/* This performs basic initialization of the UART.  This can be called very
 * early in initialization because it does not depend on having a stack.  It
 * modifies r0-r2 and r14.
 */

	.text
	.globl	up_lowsetup
	.type	up_lowsetup, function
up_lowsetup:
	/* Configure PINSEL0 */

	ldr	r0, =LPC214X_PINSEL0
	ldr	r1, [r0]
	ldr	r2, =~LPC214X_UART_PINMASK
	and	r1, r2
	ldr	r2, =LPC214X_UART_PINSEL
	orr	r1, r2
	str	r1, [r0]

	/* Configure parity, data bits, stop bits and set DLAB=1 */

	ldr	r0, =LPC214X_UART0_BASE
	mov	r1, #(LPC214X_LCR_VALUE | LPC214X_LCR_DLAB_ENABLE)
	strb	r1, [r0, #LPC214X_UART_LCR_OFFSET]

	/* Set the BAUD divisor */

	mov	r1, #(UART_BAUD(LPC214X_UART_BAUD) >> 8)
	strb	r1, [r0, #LPC214X_UART_DLM_OFFSET]

	mov	r1, #(UART_BAUD(LPC214X_UART_BAUD) & 0xff)
	strb	r1, [r0, #LPC214X_UART_DLL_OFFSET]

	/* Clear DLAB */
	
	mov	r1, #LPC214X_LCR_VALUE
	strb	r1, [r0, #LPC214X_UART_LCR_OFFSET]

	/* And return */

	mov	pc, lr
	.size	up_lowsetup, . - up_lowsetup
	.end