Re: [PATCH v1 1/1] drivers: bootcount: Add ZynqMP specific bootcount support

[Michal Simek <michal.simek@amd.com>]

On 10/30/24 15:38, Vasileios Amoiridis wrote:
> On Wed, Oct 30, 2024 at 02:13:43PM +0100, Michal Simek wrote:
>>
>>
>> On 10/29/24 19:58, Vasileios Amoiridis wrote:
>>> From: Vasileios Amoiridis <vasileios.amoiridis@cern.ch>
>>>
>>> Add native support of the bootcount mechanism in the ZynqMP by utilising internal
>>> PMU registers. The Persistent Global Storage Registers of the Platform Management
>>> Unit can keep their value during reboot cycles unless there is a POR reset, making
>>> them appropriate for the bootcount mechanism.
>>>
>>> Signed-off-by: Vasileios Amoiridis <vasileios.amoiridis@cern.ch>
>>> ---
>>>    drivers/bootcount/Kconfig            |  4 ++++
>>>    drivers/bootcount/Makefile           |  1 +
>>>    drivers/bootcount/bootcount_zynqmp.c | 28 ++++++++++++++++++++++++++++
>>>    3 files changed, 33 insertions(+)
>>>    create mode 100644 drivers/bootcount/bootcount_zynqmp.c
>>>
>>> diff --git a/drivers/bootcount/Kconfig b/drivers/bootcount/Kconfig
>>> index fa6d8e7128..95b6a9541a 100644
>>> --- a/drivers/bootcount/Kconfig
>>> +++ b/drivers/bootcount/Kconfig
>>> @@ -82,6 +82,10 @@ config BOOTCOUNT_AT91
>>>    	bool "Boot counter for Atmel AT91SAM9XE"
>>>    	depends on AT91SAM9XE
>>> +config BOOTCOUNT_ZYNQMP
>>> +	bool "Boot counter for Zynq UltraScale+ MPSoC"
>>> +	depends on ARCH_ZYNQMP
>>
>>
>> help would help to also described where that count is stored.
>>
> 
> Hi Michal,
> 
> thanks for the review. Indeed I could add it.
> 
>> And why not to have it under DM/U_BOOT_DRIVER?
>> You don't need to create compatible string for it just instantiate it.
>>
>> Look at:
>>
>> U_BOOT_DRVINFO(soc_xilinx_zynqmp) = {
>>           .name = "soc_xilinx_zynqmp",
>> };
>>
> 
> I was not fully aware of this, I could try it. Just out of curiosity, is
> this the new/prefered way of adding new drivers?
> 
>>
>>> +
>>>    config DM_BOOTCOUNT
>>>            bool "Boot counter in a device-model device"
>>>    	help
>>> diff --git a/drivers/bootcount/Makefile b/drivers/bootcount/Makefile
>>> index 245f879633..487adc1212 100644
>>> --- a/drivers/bootcount/Makefile
>>> +++ b/drivers/bootcount/Makefile
>>> @@ -3,6 +3,7 @@
>>>    obj-$(CONFIG_BOOTCOUNT_GENERIC)	+= bootcount.o
>>>    obj-$(CONFIG_BOOTCOUNT_MEM)	+= bootcount.o
>>>    obj-$(CONFIG_BOOTCOUNT_AT91)	+= bootcount_at91.o
>>> +obj-$(CONFIG_BOOTCOUNT_ZYNQMP)  += bootcount_zynqmp.o
>>
>> please put it to the end of CONFIG_BOOTCOUNT to have it at least in correct location
>>
>>>    obj-$(CONFIG_BOOTCOUNT_AM33XX)	+= bootcount_davinci.o
>>>    obj-$(CONFIG_BOOTCOUNT_RAM)	+= bootcount_ram.o
>>>    obj-$(CONFIG_BOOTCOUNT_ENV)	+= bootcount_env.o
>>> diff --git a/drivers/bootcount/bootcount_zynqmp.c b/drivers/bootcount/bootcount_zynqmp.c
>>> new file mode 100644
>>> index 0000000000..9bb801e188
>>> --- /dev/null
>>> +++ b/drivers/bootcount/bootcount_zynqmp.c
>>> @@ -0,0 +1,28 @@
>>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>> +// SPDX-FileCopyrightText: 2024 CERN (home.cern)
>>> +
>>> +#include <bootcount.h>
>>> +#include <stdio.h>
>>> +#include <zynqmp_firmware.h>
>>> +
>>> +#define PMU_PERS_GLOB_GEN_STORAGE0 0x00FFD80050
>>
>> In arch/arm/mach-zynqmp/include/mach/hardware.h
>> there is already structure defined and gen_storage0 is there too.
>> Please use it.
>>
>> Regarding this location. Exception in PMUFW is using this reg.
>> It means at the end of day it is up to you if you want to use it or not.
>>
> 
> In master branch (commit 5cca0e3f6e0ff17db92476235ea1bb9cd8cbc9eb) there
> is no gen_storage0 in the structure pmu_regs, only gen_storage4 and
> gen_storage6.

you are right but easy to extend that structure to have it there.

> 
> But in any case though, I don't use gen_storage0 which is the
> Global General Storage 0 but the Persistent Global General Storage 0
> which is in the in the offset 0x50 and is defined in [1]. According to
> this document, only registers {4:7} are used by FSBL and other Xilinx
> software products so from what I understand registers {0:3} are free to
> use. If that's not the case, which one of them is free for use?
> 
> [1]: https://docs.amd.com/r/en-US/ug1087-zynq-ultrascale-registers/PERS_GLOB_GEN_STORAGE0-PMU_GLOBAL-Register

in embedded sw you can find this
lib/sw_apps/zynqmp_pmufw/src/xpfw_start.S:77:           addik   r3,     r0, 
0xffd80050
lib/sw_apps/zynqmp_pmufw/src/xpfw_start.S:81:           addik   r3,     r0, 
0xffd80054

And there are 2 pages which describe their usage

https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18841724/PMU+Firmware#PMUFirmware-RegistersreservedforPMUFirmware

https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842019/Zynq+UltraScale+FSBL#ZynqUltraScale+FSBL-WhatarethememoryregionsandregistersreservedforFSBL?

But as I said I am fine if you choose one and you will use it for bootcount.

Thanks
M