[U-Boot] [PATCH 1/2 v2] watchdog: Implement generic watchdog_reset() version

[Michal Simek]

On 09. 04. 19 16:22, Stefan Roese wrote:
> On 09.04.19 12:45, Michal Simek wrote:
>> On 08. 04. 19 11:28, Stefan Roese wrote:
>>> This patch tries to implement a generic watchdog_reset() function that
>>> can be used by all boards that want to service the watchdog device in
>>> U-Boot. This watchdog servicing is enabled via CONFIG_WATCHDOG.
>>>
>>> Without this approach, new boards or platforms needed to implement a
>>> board specific version of this functionality, mostly copy'ing the same
>>> code over and over again into their board or platforms code base.
>>>
>>> With this new generic function, the scattered other functions are now
>>> removed to be replaced by the generic one. The new version also enables
>>> the configuration of the watchdog timeout via the DT "timeout-sec"
>>> property (if enabled via CONFIG_OF_CONTROL).
>>>
>>> This patch also adds a new flag to the GD flags, to flag that the
>>> watchdog is ready to use and adds the pointer to the watchdog device
>>> to the GD. This enables us to remove the global "watchdog_dev"
>>> variable, which was prone to cause problems because of its potentially
>>> very early use in watchdog_reset(), even before the BSS is cleared.
>>>
>>> Signed-off-by: Stefan Roese <sr at denx.de>
>>> Cc: Heiko Schocher <hs at denx.de>
>>> Cc: Tom Rini <trini at konsulko.com>
>>> Cc: Michal Simek <michal.simek at xilinx.com>
>>> Cc: "Marek Behún" <marek.behun at nic.cz>
>>> Cc: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
>>> ---
>>> This patch depends on the following patches:
>>>
>>> [1] watchdog: Move watchdog_dev to data section (BSS may not be cleared)
>>> https://patchwork.ozlabs.org/patch/1075500/
>>>
>>> [2] watchdog: Handle SPL build with watchdog disabled
>>> https://patchwork.ozlabs.org/patch/1074098/
>>>
>>> I would like to see [1] applied in this release, since its a real fix on
>>> some of the platforms with minimal chances of breakage.
>>>
>>> This patch now is a bigger rework and is intended for the next merge
>>> window.
>>>
>>> Please note that I didn't remove the "timeout-sec" handling from the
>>> driver already reading it from the DT (cdns & at91) in this patch.
>>> The reason for this is, that in the cdns case, the removal also brings
>>> a functional change, which I wanted to do in a separate patch. And
>>> in the at91 case its because there are updates to this driver already
>>> queued in the at91 next git branch which would most likely cause merge
>>> conflict. I'll send a cleanup patch for this driver later after these
>>> patches have been applied.
>>>
>>> Thanks,
>>> Stefan
>>>
>>> v2:
>>> - Rename watchdog_start() to initr_watchdog() and move it to board_r.c.
>>>    This way its only called once, after the DM subsystem has bound all
>>>    watchdog drivers. This enables the use of the currently implemented
>>>    logic of using the correct watchdog in U-Boot (via alias etc).
>>>
>>>   arch/mips/mach-mt7620/cpu.c                   | 36 -----------------
>>>   board/CZ.NIC/turris_mox/turris_mox.c          | 30 --------------
>>>   board/CZ.NIC/turris_omnia/turris_omnia.c      | 35 ----------------
>>>   .../microblaze-generic/microblaze-generic.c   | 40 -------------------
>>>   board/xilinx/zynq/board.c                     | 39 ------------------
>>>   board/xilinx/zynqmp/zynqmp.c                  | 39 ------------------
>>>   common/board_r.c                              | 40 +++++++++++++++++++
>>>   drivers/watchdog/wdt-uclass.c                 | 26 ++++++++++++
>>>   include/asm-generic/global_data.h             |  4 ++
>>>   9 files changed, 70 insertions(+), 219 deletions(-)
> 
> <snip>
> 
>>>   int board_early_init_r(void)
>>>   {
>>>       u32 val;
>>> diff --git a/common/board_r.c b/common/board_r.c
>>> index 472987d5d5..d80f16c3ed 100644
>>> --- a/common/board_r.c
>>> +++ b/common/board_r.c
>>> @@ -48,6 +48,7 @@
>>>   #include <linux/compiler.h>
>>>   #include <linux/err.h>
>>>   #include <efi_loader.h>
>>> +#include <wdt.h>
>>>     DECLARE_GLOBAL_DATA_PTR;
>>>   @@ -621,6 +622,42 @@ static int initr_bedbug(void)
>>>   }
>>>   #endif
>>>   +#if defined(CONFIG_WATCHDOG) && defined(CONFIG_WDT)
>>
>> This is not correct.
>> Here should be just CONFIG_WDT.
>>
>> Because there are cases where you want just start watchdog in u-boot but
>> never service it by u-boot.
> 
> AFAIK, this would change the current behavior. Currently, only when
> CONFIG_WATCHDOG is enabled the watchdog driver is started automatically
> in U-Boot (and serviced). If I make the change you suggest above, all
> boards defining CONFIG_WDT (DM watchdog support) will automatically
> enable the watchdog. This might make sense, but AFAICT this changes
> the current behavior.

The question is what default is. Because when I was adding support for
Zynq/ZynqMP/Microblaze this logic is used there.
I think that WDT should be there and if you think there are boards which
want to have both we can cover that by Kconfig.

Thanks,
Michal