[PATCH v2 5/5] lib: utils/reset: Add generic da9063 reset driver

[Heinrich Schuchardt <heinrich.schuchardt@canonical.com>]

On 11/3/21 08:59, Nikita Shubin wrote:
> Hello All!
> 
> On Tue, 26 Oct 2021 11:40:13 +0200
> Heinrich Schuchardt <heinrich.schuchardt@canonical.com> wrote:
> 
>> On 10/26/21 10:04, Heinrich Schuchardt wrote:
>>> On 10/15/21 15:19, Nikita Shubin wrote:
>>>> From: Nikita Shubin <n.shubin@yadro.com>
>>>>
>>>> da9063 PMIC can be used to reset/shutdown the
>>>> Sifive Unmatched board.
>>>>
>>>> shutdown is done simply by writing SHUTDOWN bit to
>>>> DA9063_REG_CONTROL_F register.
>>>>
>>>> reset via setting WAKEUP bit in DA9063_REG_CONTROL_F
>>>> register followed by masking POWER and POWER1 domains
>>>> and setting STANDBY bit in DA9063_REG_CONTROL_A,
>>>> originally discovered by Alexandre Ghiti on linux-riscv
>>>> maillists.
>>>>
>>>> Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
>>
>> Alexandre and I had the same finding for the driver:
>>
>> Reset works fine after a hard reset (via the reset button) when
>> coming from Linux.
>>
>> After a poweroff reset in U-Boot does not work.
>>
>> Our expectation is that OpenSBI ensures that the SBI system reset
>> extension works upon entry into the next firmware stage without
>> requiring any further initialization by that software.
>>
>> When a reset is requested you should make not presumption about the
>> state of the system. Simply fully initialize the da9063 state to
>> guarantee a successful reset.
> 
> Heinrich and Alexandre, i have done a small investigation:
> 
> The RTC works fine on Unmatched, just had a small issue with PLIC driver
> firing IRQ only once, here is a separate patch from Guo Ren:
> 
> https://patchwork.kernel.org/project/linux-riscv/patch/20211101131736.3800114-1-guoren at kernel.org/
> 
> And a small patch to enable da9063 as a wakeup source:
> 
> https://github.com/YADRO-KNS/linux/commit/37c2a5b2031a42af99dd7125f8c93ab71236d3fa
> 
> Indeed after power-cycle with RESET button or POWER button, I2C is
> unavailable (not initialised by U-Boot):
> 
> First boot reset after powercycle with powerdown/reset button:
> => reset
> resetting ...
> da9063_system_reset: chip is not da9063 PMIC
> 
> After rebooting with Linux reboot:
> => reset
> resetting ...
> 
> All okay and that's means that it's not a full reset, I2C was
> initialised by linux, and not resetted.

Doesn't this imply that the I2C initialization code should be added to 
OpenSBI?

Best regards

Heinrich

> 
> However if we arm the clock and go shutdown:
> 
> sh -c "echo `date '+%s' -d '+ 1 minutes'` >
> /sys/class/rtc/rtc0/wakealarm" shutdown
> shutdown
> 
> We get:
> => reset
> resetting ...
> da9063_system_reset: chip is not da9063 PMIC
> 
> So "reset" with RTC is indeed a full reset...
> 
> All above also means that "sacrificing" RTC means sacrificing user
> setted wakeup ALARM's.
> 
> May be it's worth splitting reset into WARM_REBOOT, COLD_REBOOT with
> WARM reboot is going through method proposed by Alexandre and COLD
> reboot via RTC, and explicitly specify that COLD reboot WILL overwrite
> ALARM setting ?
> 
> What do you think about this ?
> 
>>
>> Best regards
>>
>> Heinrich
>