U-Boot

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 *  linux/arch/arm/kernel/debug.S
 *
 *  Copyright (C) 1994-1999 Russell King
 *
 *  32-bit debugging code
 */
#include <linux/linkage.h>
#include <asm/assembler.h>

		.text

/*
 * Some debugging routines (useful if you've got MM problems and
 * printk isn't working).  For DEBUGGING ONLY!!!  Do not leave
 * references to these in a production kernel!
 */

#if !defined(CONFIG_DEBUG_SEMIHOSTING)
#include CONFIG_DEBUG_LL_INCLUDE
#endif

		.macro	addruart_current, rx, tmp1, tmp2
		addruart	\rx, \tmp1, \tmp2
		.endm

/*
 * Useful debugging routines
 */
ENTRY(printhex8)
		mov	r1, #8
		b	printhex
ENDPROC(printhex8)

ENTRY(printhex4)
		mov	r1, #4
		b	printhex
ENDPROC(printhex4)

ENTRY(printhex2)
		mov	r1, #2
printhex:	adr	r2, hexbuf
		add	r3, r2, r1
		mov	r1, #0
		strb	r1, [r3]
1:		and	r1, r0, #15
		mov	r0, r0, lsr #4
		cmp	r1, #10
		addlt	r1, r1, #'0'
		addge	r1, r1, #'a' - 10
		strb	r1, [r3, #-1]!
		teq	r3, r2
		bne	1b
		mov	r0, r2
		b	printascii
ENDPROC(printhex2)

hexbuf:		.space 16

		.ltorg

#ifndef CONFIG_DEBUG_SEMIHOSTING

ENTRY(printascii)
		addruart_current r3, r1, r2
		b	2f
1:		waituart r2, r3
		senduart r1, r3
		busyuart r2, r3
		teq	r1, #'\n'
		moveq	r1, #'\r'
		beq	1b
2:		teq	r0, #0
		ldrneb	r1, [r0], #1
		teqne	r1, #0
		bne	1b
		mov	pc, lr
ENDPROC(printascii)

ENTRY(printch)
		addruart_current r3, r1, r2
		mov	r1, r0
		mov	r0, #0
		b	1b
ENDPROC(printch)

#else

ENTRY(printascii)
		mov	r1, r0
		mov	r0, #0x04		@ SYS_WRITE0
	ARM(	svc	#0x123456	)
	THUMB(	svc	#0xab		)
		mov	pc, lr
ENDPROC(printascii)

ENTRY(printch)
		adr	r1, hexbuf
		strb	r0, [r1]
		mov	r0, #0x03		@ SYS_WRITEC
	ARM(	svc	#0x123456	)
	THUMB(	svc	#0xab		)
		mov	pc, lr
ENDPROC(printch)

ENTRY(debug_ll_addr)
		mov	r2, #0
		str	r2, [r0]
		str	r2, [r1]
		mov	pc, lr
ENDPROC(debug_ll_addr)

#endif