Re: [PATCH v2 1/3] ARM: dts: aspeed: mtjade: Add some gpios

[Thang Nguyen]

On 19/10/2021 13:46, Joel Stanley wrote:
> On Tue, 19 Oct 2021 at 06:02, Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> > Add S0_SCP_AUTH_FAIL, S1_SCP_AUTH_FAIL gpios to indicates firmware
> > authentication fail on each socket.
>
> These use the gpio-keys API to expose the GPIOs. I think OpenBMC is
> moving away from this abstraction, and instead reading the GPIOs with
> the gpio chardev interface.
Can you give an example of the suggested change?
> > Add gpio RTC_BAT_SEN_EN to enable RTC battery adc sensor.
> >
> > Add BMC_I2C4_O_EN gpio to go high at boot to enable access to I2C4 bus.
>
> OpenBMC has started a process to document GPIOs that are exposed to
> userspace, initially so a common userspace can be used across
> machines. I like doing it for the additional reason that it provides
> consistency in the naming.
[Thang] The BMC_I2C4_O_EN GPIO is used in kernel only which enabling 
access to all I2C devices in I2C4 bus, like FRU EEPROM. As it is used as 
gpio-hog, no userspace access is allowed/intended. It can't be 
configured in userspace as FRU EEPROM is probed only in kernel boot.
> https://github.com/openbmc/docs/blob/master/designs/device-tree-gpio-naming.md
>
> If you could take a look at that document and add your GPIOs where
> possible, and then update the device tree.
[Thang] I am aware of this GPIO naming convention document. But I think 
it is to define common name for special GPIOs that applications can use.

> > Signed-off-by: Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Thang Nguyen <thang@xxxxxxxxxxxxxxxxxxxxxx>
> > ---
> > v2:
> >    - None
> >
> >   .../arm/boot/dts/aspeed-bmc-ampere-mtjade.dts | 21 ++++++++++++++++++-
> >   1 file changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/boot/dts/aspeed-bmc-ampere-mtjade.dts b/arch/arm/boot/dts/aspeed-bmc-ampere-mtjade.dts
> > index 57b0c45a2298..3515d55bd312 100644
> > --- a/arch/arm/boot/dts/aspeed-bmc-ampere-mtjade.dts
> > +++ b/arch/arm/boot/dts/aspeed-bmc-ampere-mtjade.dts
> > @@ -86,6 +86,18 @@ S0_cpu_fault {
> >                          linux,code = <ASPEED_GPIO(J, 1)>;
> >                  };
> >
> > +               S0_scp_auth_fail {
> > +                       label = "S0_SCP_AUTH_FAIL";
> > +                       gpios = <&gpio ASPEED_GPIO(J, 2) GPIO_ACTIVE_LOW>;
> > +                       linux,code = <ASPEED_GPIO(J, 2)>;
> > +               };
> > +
> > +               S1_scp_auth_fail {
> > +                       label = "S1_SCP_AUTH_FAIL";
> > +                       gpios = <&gpio ASPEED_GPIO(Z, 5) GPIO_ACTIVE_LOW>;
> > +                       linux,code = <ASPEED_GPIO(Z, 5)>;
> > +               };
> > +
> >                  S1_overtemp {
> >                          label = "S1_OVERTEMP";
> >                          gpios = <&gpio ASPEED_GPIO(Z, 6) GPIO_ACTIVE_LOW>;
> > @@ -590,7 +602,7 @@ &gpio {
> >          /*Q0-Q7*/       "","","","","","UID_BUTTON","","",
> >          /*R0-R7*/       "","","BMC_EXT_HIGHTEMP_L","OCP_AUX_PWREN",
> >                          "OCP_MAIN_PWREN","RESET_BUTTON","","",
> > -       /*S0-S7*/       "","","","","","","","",
> > +       /*S0-S7*/       "","","","","RTC_BAT_SEN_EN","","","",
>
> I suggest you create a proposal to call this one
> battery-voltage-read-enable. I know that some of the IBM machines
> intend to have this same GPIO.
[Thang] is there any application to use this pin name?
> >          /*T0-T7*/       "","","","","","","","",
> >          /*U0-U7*/       "","","","","","","","",
> >          /*V0-V7*/       "","","","","","","","",
> > @@ -604,4 +616,11 @@ &gpio {
> >                          "S1_BMC_DDR_ADR","","","","",
> >          /*AC0-AC7*/     "SYS_PWR_GD","","","","","BMC_READY","SLAVE_PRESENT_L",
> >                          "BMC_OCP_PG";
> > +
> > +       i2c4_o_en {
> > +               gpio-hog;
> > +               gpios = <ASPEED_GPIO(Y, 2) GPIO_ACTIVE_HIGH>;
> > +               output-high;
> > +               line-name = "BMC_I2C4_O_EN";
> > +       };
> >   };
> > --
> > 2.28.0