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MIPS: pbl: add low-level debug asm macros for ns16550 

This patch adds macros for ns16550 port initialisation
and single char output. The macros can be used in
MIPS asm pbl code.

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Antony Pavlov 2013-06-01 11:52:45 +04:00 committed by Sascha Hauer
parent 3c90cbfa64
commit 68d80258ef
1 changed files with 100 additions and 0 deletions
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100
arch/mips/include/asm/debug_ll_ns16550.h Normal file
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/*
* Copyright (C) 2012, 2013 Antony Pavlov <antonynpavlov@gmail.com>
*
* This file is part of barebox.
* See file CREDITS for list of people who contributed to this project.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* 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.
*
*/
/** @file
* This file contains declaration for early output support
*/
#ifndef __INCLUDE_MIPS_ASM_DEBUG_LL_NS16550_H__
#define __INCLUDE_MIPS_ASM_DEBUG_LL_NS16550_H__
#ifdef CONFIG_DEBUG_LL
#ifndef DEBUG_LL_UART_ADDR
#error DEBUG_LL_UART_ADDR is undefined!
#endif
#ifndef DEBUG_LL_UART_SHIFT
#error DEBUG_LL_UART_SHIFT is undefined!
#endif
#ifndef DEBUG_LL_UART_DIVISOR
#error DEBUG_LL_UART_DIVISOR is undefined!
#endif
#endif /* CONFIG_DEBUG_LL */
#define UART_THR (0x0 << DEBUG_LL_UART_SHIFT)
#define UART_DLL (0x0 << DEBUG_LL_UART_SHIFT)
#define UART_DLM (0x1 << DEBUG_LL_UART_SHIFT)
#define UART_LCR (0x3 << DEBUG_LL_UART_SHIFT)
#define UART_LSR (0x5 << DEBUG_LL_UART_SHIFT)
#define UART_LCR_W 0x07 /* Set UART to 8,N,2 & DLAB = 0 */
#define UART_LCR_DLAB 0x87 /* Set UART to 8,N,2 & DLAB = 1 */
#define UART_LSR_THRE 0x20 /* Xmit holding register empty */
/*
* Macros for use in assembly language code
*/
.macro debug_ll_ns16550_init
#ifdef CONFIG_DEBUG_LL
la t0, DEBUG_LL_UART_ADDR
li t1, UART_LCR_DLAB /* DLAB on */
sb t1, UART_LCR(t0) /* Write it out */
li t1, DEBUG_LL_UART_DIVISOR
sb t1, UART_DLL(t0) /* write low order byte */
srl t1, t1, 8
sb t1, UART_DLM(t0) /* write high order byte */
li t1, UART_LCR_W /* DLAB off */
sb t1, UART_LCR(t0) /* Write it out */
#endif /* CONFIG_DEBUG_LL */
.endm
/*
* output a character in a0
*/
.macro debug_ll_ns16550_outc chr
#ifdef CONFIG_DEBUG_LL
li a0, \chr
la t0, DEBUG_LL_UART_ADDR
1: lbu t1, UART_LSR(t0) /* get line status */
nop
andi t1, t1, UART_LSR_THRE /* check for transmitter empty */
beqz t1, 1b /* try again */
nop
sb a0, UART_THR(t0) /* write the character */
#endif /* CONFIG_DEBUG_LL */
.endm
/*
* output CR + NL
*/
.macro debug_ll_ns16550_outnl
#ifdef CONFIG_DEBUG_LL
debug_ll_ns16550_outc '\r'
debug_ll_ns16550_outc '\n'
#endif /* CONFIG_DEBUG_LL */
.endm
#endif /* __INCLUDE_MIPS_ASM_DEBUG_LL_NS16550_H__ */