2 files changed, 138 insertions, 0 deletions
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 1ef2400..d74e4b8 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -48,6 +48,8 @@ ifndef CONFIG_ARM64
 obj-y	+= cache-cp15.o
 endif
 
+obj-$(CONFIG_DEBUG_LL)	+= debug.o
+
 # For EABI conformant tool chains, provide eabi_compat()
 ifneq (,$(findstring -mabi=aapcs-linux,$(PLATFORM_CPPFLAGS)))
 extra-y	+= eabi_compat.o
diff --git a/arch/arm/lib/debug.S b/arch/arm/lib/debug.S
new file mode 100644
index 0000000..760ba74
--- /dev/null
+++ b/arch/arm/lib/debug.S
@@ -0,0 +1,136 @@
+/*
+ *  linux/arch/arm/kernel/debug.S
+ *
+ *  Copyright (C) 1994-1999 Russell King
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ *
+ *  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
+
+#ifdef CONFIG_MMU
+		.macro	addruart_current, rx, tmp1, tmp2
+		addruart	\tmp1, \tmp2, \rx
+		mrc		p15, 0, \rx, c1, c0
+		tst		\rx, #1
+		moveq		\rx, \tmp1
+		movne		\rx, \tmp2
+		.endm
+
+#else /* !CONFIG_MMU */
+		.macro	addruart_current, rx, tmp1, tmp2
+		addruart	\rx, \tmp1, \tmp2
+		.endm
+
+#endif /* CONFIG_MMU */
+
+/*
+ * 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)
+
+#ifdef CONFIG_MMU
+ENTRY(debug_ll_addr)
+		addruart r2, r3, ip
+		str	r2, [r0]
+		str	r3, [r1]
+		mov	pc, lr
+ENDPROC(debug_ll_addr)
+#endif
+
+#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