SPL JTAG boot mode

RFC PATCH New Michal Simek 4 participants 6 messages Aug 11, 2014 – Aug 18, 2014 1 message not in the archive

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Arm (32-bit) Microblaze architecture

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Michal Simek

author

2014-08-11 13:03 UTC #0 lore raw

cover SPL JTAG boot mode

Hi,

I have got this patch some time ago but I am not still 100% sure about use case. Anyway Soren uses this mode that's why let me send this patch and we can discuss if this can be useful for someone else too.

The use case is to load U-Boot SPL to do init HW and then load images via JTAG because RAM is initialized and then run full u-boot.
There is an option to do HW initialization without U-Boot SPL but there are some differences and it is just better to directly use code which will run on the board when everything is tested.

Thanks for your inputs,
Michal

Michal Simek (1):
ARM: spl: Introduce JTAG mode

 arch/arm/include/asm/spl.h        | 1 +
 arch/microblaze/include/asm/spl.h | 1 +
 common/spl/spl.c                  | 7 +++++++
 3 files changed, 9 insertions(+)

--
1.8.2.3

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Michal Simek

author

2014-08-11 13:03 UTC #1 lore raw

RFC PATCH 1/1 ARM: spl: Introduce JTAG mode

Introduce simple JTAG mode which stops CPU before U-Boot image processing.

Signed-off-by Ezra Savard <[email protected]>

Signed-off-by Michal Simek <[email protected]>

Acked-by S?ren Brinkmann <[email protected]>

---

 arch/arm/include/asm/spl.h        | 1 +
 arch/microblaze/include/asm/spl.h | 1 +
 common/spl/spl.c                  | 7 +++++++
 3 files changed, 9 insertions(+)

arch/arm/include/asm/spl.h +1 -0

index e5daf8912712..d690c5914f05 100644
@@ -26,6 +26,7 @@ enum {
 	BOOT_DEVICE_SPI,
 	BOOT_DEVICE_SATA,
 	BOOT_DEVICE_I2C,
+	BOOT_DEVICE_JTAG,
 	BOOT_DEVICE_NONE
 };
 #endif

arch/microblaze/include/asm/spl.h +1 -0

index c1cae6cf0fe6..3715f4862a01 100644
@@ -12,5 +12,6 @@
 #define BOOT_DEVICE_RAM		1
 #define BOOT_DEVICE_NOR		2
 #define BOOT_DEVICE_SPI		3
+#define BOOT_DEVICE_JTAG	4
 
 #endif

common/spl/spl.c +7 -0

index 774fdad2523b..de1de880b738 100644
@@ -215,6 +215,13 @@ void board_init_r(gd_t *dummy1, ulong dummy2)
 		spl_sata_load_image();
 		break;
 #endif
+#ifdef CONFIG_SPL_JTAG_SUPPORT
+	case BOOT_DEVICE_JTAG:
+		debug("Ready for image");
+		while (1)
+			;
+		break;
+#endif
 	default:
 		debug("SPL: Un-supported Boot Device\n");
 		hang();

--
1.8.2.3

Tom Rini

2014-08-11 13:17 UTC #2 lore raw

cover SPL JTAG boot mode

In reply to Michal Simek

Quoted 7 lines · Michal Simek

Hi,
I have got this patch some time ago but I am not still 100% sure about use case. Anyway Soren uses this mode that's why let me send this patch and we can discuss if this can be useful for someone else too.

Quoted 7 lines

The use case is to load U-Boot SPL to do init HW and then load images via JTAG because RAM is initialized and then run full u-boot.
There is an option to do HW initialization without U-Boot SPL but there are some differences and it is just better to directly use code which will run on the board when everything is tested.

So in this case, you attach JTAG to the board, halt on reset, reset the board. JTAG load in SPL and fiddle memory so that BOOT_DEVICE_JTAG is set, let SPL run, halt when you see the print (or set a breakpoint for that part, either way), then load U-Boot via JTAG, resume over the while loop, and then debug U-Boot as needed?

Signature · 8 lines

Tom
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Michal Simek

author

2014-08-11 13:29 UTC #3 lore raw

cover SPL JTAG boot mode

Quoted 17 lines · Tom Rini

Quoted 7 lines · Michal Simek
Hi,
I have got this patch some time ago but I am not still 100% sure about use case. Anyway Soren uses this mode that's why let me send this patch and we can discuss if this can be useful for someone else too.
Quoted 7 lines
The use case is to load U-Boot SPL to do init HW and then load images via JTAG because RAM is initialized and then run full u-boot.
There is an option to do HW initialization without U-Boot SPL but there are some differences and it is just better to directly use code which will run on the board when everything is tested.

Quoted 3 lines

So in this case, you attach JTAG to the board, halt on reset, reset the board. JTAG load in SPL and fiddle memory so that BOOT_DEVICE_JTAG is set, let SPL run,

BOOT_DEVICE_JTAG for zynq case will be setup in spl_boot_device() based on dip-switch boot mode setup read from SLCR.

Quoted 3 lines

halt when you see the print (or set a breakpoint for
that part, either way), then load U-Boot via JTAG, resume over the while loop, and then debug U-Boot as needed?

In general that's my impression how Soren uses it. I would let him to confirm that this is his use case.

Not sure if he is just loading images when cpu is in while(1) loop and let u-boot spl continue. I can imagine that it will be just easier to let u-boot spl end up in while loop instead of trying to find out address for adding breakpoint.

I would let Soren or Ezra to justify this use case because I have doubts.

Thanks,
Michal

A message that is not in the archive (sent off-list or not yet received): [email protected]

Ezra Savard

2014-08-11 16:28 UTC #5 lore raw

cover SPL JTAG boot mode

Quoted 37 lines

-----Original Message-----
From: Michal Simek [mailto:michal.simek at xilinx.com]
Sent: Monday, August 11, 2014 6:30 AM
To: Tom Rini; Michal Simek
Cc: u-boot at lists.denx.de; Stephen Warren; Ezra Savard; Soren Brinkmann; Roger Quadros
Subject: Re: [U-Boot] [RFC PATCH 0/1] SPL JTAG boot mode
Quoted 15 lines · Tom Rini
Quoted 7 lines · Michal Simek
Hi,
I have got this patch some time ago but I am not still 100% sure about use case. Anyway Soren uses this mode that's why let me send this patch and we can discuss if this can be useful for someone else too.
Quoted 5 lines
The use case is to load U-Boot SPL to do init HW and then load images via JTAG because RAM is initialized and then run full u-boot. There is an option to do HW initialization without U-Boot SPL but there are some differences and it is just better to directly use code which will run on the board when everything is tested.
Quoted 3 lines
So in this case, you attach JTAG to the board, halt on reset, reset the board. JTAG load in SPL and fiddle memory so that BOOT_DEVICE_JTAG is set, let SPL run,
BOOT_DEVICE_JTAG for zynq case will be setup in spl_boot_device() based on dip-switch boot mode setup read from SLCR.
Quoted 3 lines
halt when you see the print (or set a breakpoint for that part, either way), then load U-Boot via JTAG, resume over the while loop, and then debug U-Boot as needed?

Quoted 7 lines

In general that's my impression how Soren uses it. I would let him to confirm that this is his use case.
Not sure if he is just loading images when cpu is in while(1) loop and
let u- boot spl continue. I can imagine that it will be just easier to
let u-boot spl end up in while loop instead of trying to find out address for adding breakpoint.

In our use case, we do not have physical access to the board.

Previously, u-boot spl would hang when ready for the u-boot image; the explicit JTAG boot mode keeps from attempting to load images from RAM.

The while(1) loop is, as mentioned by Michal, just an easy, known place to let the u-boot spl end up before loading images.

Soren will be back in one week and it would be best for him to chime in.

Thanks,
Ezra

Quoted 4 lines

I would let Soren or Ezra to justify this use case because I have doubts.
Thanks,
Michal

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Sören Brinkmann

2014-08-18 16:35 UTC #6 lore raw

cover SPL JTAG boot mode

In reply to Tom Rini

Quoted 17 lines · Tom Rini

Quoted 7 lines · Michal Simek
Hi,
I have got this patch some time ago but I am not still 100% sure about use case. Anyway Soren uses this mode that's why let me send this patch and we can discuss if this can be useful for someone else too.
Quoted 7 lines
The use case is to load U-Boot SPL to do init HW and then load images via JTAG because RAM is initialized and then run full u-boot.
There is an option to do HW initialization without U-Boot SPL but there are some differences and it is just better to directly use code which will run on the board when everything is tested.

Quoted 5 lines

So in this case, you attach JTAG to the board, halt on reset, reset the board. JTAG load in SPL and fiddle memory so that BOOT_DEVICE_JTAG is set, let SPL run, halt when you see the print (or set a breakpoint for that part, either way), then load U-Boot via JTAG, resume over the while loop, and then debug U-Boot as needed?

That is pretty much the flow correct. But I do not use it to debug U-Boot, but boot our boards in our boardfarm. The flow is

1. Connect JTAG debugger
2. Download and run SPL
3. Stop execution when the SPL is done (and did initialize the DDR)
4. Load U-Boot and run U-Boot through JTAG
5. boot full OS etc.

I.e. the JTAG boot flow is used in automation quite a lot here.

Thanks,
S?ren