[PATCH] arm64: zynqmp: Support semhosting boot method

[Michal Simek]

On 2/16/24 14:48, Michal Simek wrote:
> 
> 
> On 2/15/24 20:31, Sean Anderson wrote:
>> On 2/15/24 14:08, Michal Simek wrote:
>>>
>>>
>>> On 2/15/24 18:19, Sean Anderson wrote:
>>>> Currently, when we boot from JTAG we try to boot U-Boot from RAM.
>>>> However, this is a bit tricky to time, since the debugger has to wait
>>>> for SPL to initialize RAM before it can load U-Boot. This can result in
>>>> long waits, since occasionally initializing RAM (and other things in
>>>> psu_init) takes a long time to complete and the debugger must wait for
>>>> this worst case.
>>>>
>>>> Support semihosting if it is enabled, as it lets U-Boot tell the
>>>> debugger when we are ready for the image. This means we don't have to
>>>> wait any more than necessary. We don't change the default config to
>>>> ensure we don't break compatibility with existing debuggers that don't
>>>> expect us to hit semihosting breakpoints.
>>>>
>>>> Signed-off-by: Sean Anderson <sean.anderson at seco.com>
>>>> ---
>>>>
>>>>    arch/arm/mach-zynqmp/spl.c | 10 ++++++++--
>>>>    1 file changed, 8 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm/mach-zynqmp/spl.c b/arch/arm/mach-zynqmp/spl.c
>>>> index a0f35f36faa..5af735aa5ce 100644
>>>> --- a/arch/arm/mach-zynqmp/spl.c
>>>> +++ b/arch/arm/mach-zynqmp/spl.c
>>>> @@ -9,6 +9,7 @@
>>>>    #include <image.h>
>>>>    #include <init.h>
>>>>    #include <log.h>
>>>> +#include <semihosting.h>
>>>>    #include <spl.h>
>>>>    #include <linux/delay.h>
>>>>
>>>> @@ -66,6 +67,11 @@ void spl_board_init(void)
>>>>    }
>>>>    #endif
>>>>
>>>> +static u32 jtag_boot_device(void)
>>>> +{
>>>> +       return semihosting_enabled() ? BOOT_DEVICE_SMH : BOOT_DEVICE_RAM;
>>>> +}
>>>> +
>>>>    void board_boot_order(u32 *spl_boot_list)
>>>>    {
>>>>           spl_boot_list[0] = spl_boot_device();
>>>> @@ -75,7 +81,7 @@ void board_boot_order(u32 *spl_boot_list)
>>>>           if (spl_boot_list[0] == BOOT_DEVICE_MMC2)
>>>>                   spl_boot_list[1] = BOOT_DEVICE_MMC1;
>>>>
>>>> -       spl_boot_list[2] = BOOT_DEVICE_RAM;
>>>> +       spl_boot_list[2] = jtag_boot_device();
>>>>    }
>>>>
>>>>    u32 spl_boot_device(void)
>>>> @@ -97,7 +103,7 @@ u32 spl_boot_device(void)
>>>>
>>>>           switch (bootmode) {
>>>>           case JTAG_MODE:
>>>> -               return BOOT_DEVICE_RAM;
>>>> +               return jtag_boot_device();
>>>>    #ifdef CONFIG_SPL_MMC
>>>>           case SD_MODE1:
>>>>           case SD1_LSHFT_MODE: /* not working on silicon v1 */
>>>
>>> Good timing. Can you please tell me how to test this? What's the setup?
>>> Which debugger are you using?
>>
>> I am using OpenOCD with the patches at 
>> https://review.openocd.org/c/openocd/+/8133
>>
> 
> I am trying it on the top of the latest git but getting issue with event block 
> and no idea how to fix it.
> 
> # sudo openocd -f 
> /usr/local/share/openocd/scripts/interface/ftdi/digilent_jtag_hs3.cfg -f 
> /usr/local/share/openocd/scripts/target/xilinx_zynqmp.cfg
> Open On-Chip Debugger 0.12.0+dev-01509-g6d288937cb2d (2024-02-16-12:22)
> Licensed under GNU GPL v2
> For bug reports, read
>      http://openocd.org/doc/doxygen/bugs.html
> Info : auto-selecting first available session transport "jtag". To override use 
> 'transport select <transport>'.
> wrong # args: should be "-event <event-name> <event-body>"
> 
> 
> Do you know how to fix it?


I actually bisect it and found that it is caused by
jtag: rewrite jim_jtag_configure() as COMMAND_HANDLER
ea2e26f7d521f5755b4bfda7bf12d99650277421

# sudo openocd -f 
/usr/local/share/openocd/scripts/interface/ftdi/digilent_jtag_smt2_nc.cfg -f 
/usr/local/share/openocd/scripts/target/xilinx_zynqmp.cfg
Open On-Chip Debugger 0.12.0+dev-01512-g214206ebb972 (2024-02-16-15:38)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
none separate
Info : auto-selecting first available session transport "jtag". To override use 
'transport select <transport>'.
Info : Hardware thread awareness created
boot_apu
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Warn : An adapter speed is not selected in the init scripts. OpenOCD will try to 
run the adapter at very low speed (100 kHz).
Warn : To remove this warnings and achieve reasonable communication speed with 
the target, set "adapter speed" or "jtag_rclk" in the init scripts.
Info : clock speed 100 kHz
Info : TAP uscale.tap does not have valid IDCODE (idcode=0x48e70126)
Info : JTAG tap: uscale.ps tap/device found: 0x24738093 (mfg: 0x049 (Xilinx), 
part: 0x4738, ver: 0x2)
Info : JTAG tap: uscale.tap tap/device found: 0x5ba00477 (mfg: 0x23b (ARM Ltd), 
part: 0xba00, ver: 0x5)
Info : JTAG tap: uscale.ps tap/device found: 0x24738093 (mfg: 0x049 (Xilinx), 
part: 0x4738, ver: 0x2)
Error: JTAG-DP STICKY ERROR
Error: [uscale.a53.0] Examination failed
Warn : target uscale.a53.0 examination failed
Info : [uscale.axi] Examination succeed
Info : starting gdb server for uscale.a53.0 on 3333
Info : Listening on port 3333 for gdb connections
Info : gdb port disabled


but with zcu102 I am still not able to connect because error above.
The same behavior with recording SOM IDs I see on kv260 (via hs3 cable).
It looks like that not everything is working for zynqmp.

And no issue with xsdb.

Thanks,
Michal