/**************************************************************************
* arch/arm/src/imx/imx_lowputc.S
* arch/arm/src/chip/imx_lowputc.S
*
* Copyright (C) 2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 "chip.h"
#include "up_internal.h"
#include "up_arch.h"
/**************************************************************************
* Private Definitions
**************************************************************************/
/**************************************************************************
* 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 */
#ifdef CONFIG_UART1_SERIAL_CONSOLE
ldr r2, =IMX_UART1_VBASE /* r2=UART1 base */
#else
ldr r2, =IMX_UART2_VBASE /* r2=UART0 base */
#endif
/* Poll the TX fifo trigger level bit of the UART status register #2 .
* When the bit is non-zero, the TX Buffer FIFO is empty.
*/
1: ldr r1, [r2, #UART_USR2]
tst r1, #UART_USR2_TXFE
beq 1b
/* Send the character by writing it into the UART_DTRR
* register.
*/
str r0, [r2, #UART_TXD0]
/* If the character that we just sent was a linefeed,
* then send a carriage return as well.
*/
teq r0, #'\n'
moveq r0, #'\r'
beq 1b
/* Wait for the tranmsit regiser to be emptied. When the bit is
* non-zero, the TX Buffer FIFO is empty.
*/
2: ldrh r1, [r2, #UART_USR2]
tst r1, #UART_USR2_TXFE
beq 2b
/* Then return */
mov pc, lr
.end
