Introduce low-level debug for ARM architecture

We do not have to distinguish CONFIG_TARGET_VEXPRESS_AEMV8A_SEMI from CONFIG_TARGET_VEXPRESS_AEMV8A. Rename the former to the latter.

Signed-off-by Masahiro Yamada <[email protected]>

Cc David Feng <[email protected]>

Cc Steve Rae <[email protected]>

---

  arch/arm/Kconfig                       |  3 ---
  board/armltd/vexpress64/Kconfig        | 20 --------------------
  configs/vexpress_aemv8a_semi_defconfig |  2 +-
  3 files changed, 1 insertion(+), 24 deletions(-)

arch/arm/Kconfig +0 -3

index e97f94d..2bd19b8 100644
@@ -719,9 +719,6 @@ config TARGET_VENICE2
  config TARGET_VEXPRESS_AEMV8A
  	bool "Support vexpress_aemv8a"
 
-config TARGET_VEXPRESS_AEMV8A_SEMI
-	bool "Support vexpress_aemv8a_semi"
-
  config TARGET_LS2085A_EMU
  	bool "Support ls2085a_emu"
 

board/armltd/vexpress64/Kconfig +0 -20

index 91eb8d2..d8c4e21 100644
@@ -17,23 +17,3 @@ config SYS_CONFIG_NAME
  	default "vexpress_aemv8a"
 
  endif
-
-if TARGET_VEXPRESS_AEMV8A_SEMI
-
-config SYS_CPU
-	string
-	default "armv8"
-
-config SYS_BOARD
-	string
-	default "vexpress64"
-
-config SYS_VENDOR
-	string
-	default "armltd"
-
-config SYS_CONFIG_NAME
-	string
-	default "vexpress_aemv8a"
-
-endif

configs/vexpress_aemv8a_semi_defconfig +1 -1

index e6dd8e7..24b868c 100644
@@ -1,3 +1,3 @@
  CONFIG_SYS_EXTRA_OPTIONS="ARM64,SEMIHOSTING,BASE_FVP"
  CONFIG_ARM=y
-CONFIG_TARGET_VEXPRESS_AEMV8A_SEMI=y
+CONFIG_TARGET_VEXPRESS_AEMV8A=y

U-Boot does not have arch/arm/kernel, include/uapi directories, This commit copies files as follows:

   Location in Linux               -> Location in U-Boot

   arch/arm/kernel/debug.S         -> arch/arm/lib/debug.S
   arch/arm/include/debug/8250.S   -> arch/arm/include/debug/8250.S
   include/uapi/linux/serial_reg.h -> include/linux/serial_reg.h

Signed-off-by Masahiro Yamada <[email protected]>

---

  arch/arm/include/debug/8250.S |  54 ++++++
  arch/arm/lib/debug.S          | 138 +++++++++++++++
  include/linux/serial_reg.h    | 389 ++++++++++++++++++++++++++++++++++++++++++
  3 files changed, 581 insertions(+)

create mode 100644 arch/arm/include/debug/8250.S create mode 100644 arch/arm/lib/debug.S create mode 100644 include/linux/serial_reg.h

arch/arm/include/debug/8250.S new file +0 -0

new file mode 100644
index 0000000..7a2baf9

Please use SPDX license identifiers instead. Please fix this globally.

U-Boot does not have arch/arm/kernel, include/uapi directories, This commit copies files as follows:

   Location in Linux               -> Location in U-Boot

   arch/arm/kernel/debug.S         -> arch/arm/lib/debug.S
   arch/arm/include/debug/8250.S   -> arch/arm/include/debug/8250.S
   include/uapi/linux/serial_reg.h -> include/linux/serial_reg.h

Signed-off-by Masahiro Yamada <[email protected]>

---

arch/arm/lib/debug.S new file +17 -0

new file mode 100644
index 0000000..14f7c3b
@@ -0,0 +1,138 @@
+/*
+ *  linux/arch/arm/kernel/debug.S
+ *
+ *  Copyright (C) 1994-1999 Russell King
+ *
+ * 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.
+ *
+ *  32-bit debugging code
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+		.text
+
+/*

Hello Masahiro,
I tried to test this on Trats2(Exynos4412) with required files from the linux and the code doesn't build.

Quoted 3 lines · Masahiro Yamada

U-Boot does not have arch/arm/kernel, include/uapi directories, This commit copies files as follows:

arch/arm/lib/debug.S line 27

Quoted 13 lines

arch/arm/lib/debug.S new file +13 -0

+		.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

This config: "CONFIG_MMU" is nowhere defined in the u-boot.

U-boot uses (n)def CONFIG_SYS_DCACHE_OFF - for enable/disable the mmu in ARM.

But when I do the change like this:

(quoted diff) +1 -1

-#ifdef CONFIG_MMU
+#ifndef CONFIG_SYS_DCACHE_OFF

Then I got the data abort, after use a printch(). But without this change the printch() function works fine (after the uart init).

Quoted 6 lines

arch/arm/lib/debug.S new file +6 -0

+		.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

arch/arm/lib/debug.S line 38

Quoted 5 lines

arch/arm/lib/debug.S new file +5 -0

+		.endm
+
+#else /* !CONFIG_MMU */
+		.macro	addruart_current, rx, tmp1, tmp2
+		addruart	\rx, \tmp1

Generates build error:
This asm macro: "addruart" gets 3 arguments but in this place got only two. After fix - works fine. It's strange, no one use this in the kernel before?

And moreover I think that functions declarations are welcome for this code.

Best regards,
-- Przemyslaw Marczak
Samsung R&D Institute Poland
Samsung Electronics
p.marczak at samsung.com

Hi Przemyslaw,

Quoted 7 lines · On Mon, 25 Aug 2014 11:03:13 +0200 Przemyslaw Marczak <[email protected]>…

Hello Masahiro,
I tried to test this on Trats2(Exynos4412) with required files from the linux and the code doesn't build.

Quoted 3 lines · Masahiro Yamada

U-Boot does not have arch/arm/kernel, include/uapi directories, This commit copies files as follows:

Quoted 15 lines

arch/arm/lib/debug.S line 27

Quoted 13 lines

arch/arm/lib/debug.S new file +13 -0

+		.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

This config: "CONFIG_MMU" is nowhere defined in the u-boot.

Yes, CONFIG_MMU is never defined in U-Boot,
therefore, the code inside #ifdef CONFIG_MMU ... #endif is never enabled.

Quoted 1 line

U-boot uses (n)def CONFIG_SYS_DCACHE_OFF - for enable/disable the mmu in ARM.

CONFIG_SYS_DCACHE_OFF has nothing to do with this debug function.

Quoted 4 lines

But when I do the change like this:

(quoted diff) +1 -1

-#ifdef CONFIG_MMU
+#ifndef CONFIG_SYS_DCACHE_OFF

Quoted 1 line

Then I got the data abort, after use a printch(). But without this change the printch() function works fine (after the uart init).

Please do not change this part.
On U-Boot, virt addr is always the same as phys addr, so use the code for non CONFIG_MMU.

Quoted 17 lines

Quoted 4 lines

arch/arm/lib/debug.S new file +1 -0

+		.macro	addruart_current, rx, tmp1, tmp2

arch/arm/lib/debug.S line 38

Quoted 10 lines

arch/arm/lib/debug.S new file +10 -0

+		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

Generates build error:
This asm macro: "addruart" gets 3 arguments but in this place got only two. After fix - works fine. It's strange, no one use this in the kernel before?

I guess you imported arch/arm/include/debug/exynos.S

In Linux, unfortunately, the number of arguments of this macro is different between CONFIG_MMU and non CONFIG_MMU.

(Fox ex, addruart in arch/arm/include/debug/efm32.S in Linux gives only two arguments.)

Could you modify as follows and try it again, please?

--- a/arch/arm/lib/debug.S
+++ b/arch/arm/lib/debug.S
@@ -33,7 +33,7 @@

#else /* !CONFIG_MMU */
.macro addruart_current, rx, tmp1, tmp2

  -               addruart        \rx, \tmp1
  +               addruart        \rx, \tmp1, \tmp2

.endm

   #endif /* CONFIG_MMU */

If it works, I will post v2.

Best Regards
Masahiro Yamada

Quoted 7 lines

And moreover I think that functions declarations are welcome for this code.

Best regards,
-- Przemyslaw Marczak
Samsung R&D Institute Poland
Samsung Electronics
p.marczak at samsung.com

I have been in trouble for a while to debug some nasty problem where neighter a debugger nor printf() function is available.

I found the lowlevel debug feature in ARM Linux can be used as is in U-Boot too.

I tested this series on our SoCs (32bit ARM, specificly Coretex-A9). Because I was not sure about aarch64, I have this feature depend on "! ARM64".

1/4 and 2/4 refactor a bit and move CONFIG_ARM64 to Kconfig.

3/4 imports some source files from Linux 3.16 and
4/4 adds the Kconfig menu.

Quoted 6 lines · Masahiro Yamada

I have been in trouble for a while to debug some nasty problem where neighter a debugger nor printf() function is available.

I found the lowlevel debug feature in ARM Linux can be used as is in U-Boot too.

Quoted 8 lines

I tested this series on our SoCs (32bit ARM, specificly Coretex-A9). Because I was not sure about aarch64, I have this feature depend on "! ARM64".

1/4 and 2/4 refactor a bit and move CONFIG_ARM64 to Kconfig.

3/4 imports some source files from Linux 3.16 and
4/4 adds the Kconfig menu.

Dear Masahiro,

How do you use this debug facility? Do you print to memory?

I don't know enough to comment on the patch. I don't see CP15 co-process in the SoC I am debugging.