RE: [PATCH v1 5/9] firmware: keembay: Add support for Trusted Firmware Service call

["Zulkifli, Muhammad Husaini" <muhammad.husaini.zulkifli@intel.com>]

Hi Cristian, Sudeep and Mark,

>-----Original Message-----
>From: Cristian Marussi <cristian.marussi@arm.com>
>Sent: Monday, January 18, 2021 8:02 PM
>To: Zulkifli, Muhammad Husaini <muhammad.husaini.zulkifli@intel.com>
>Cc: Sudeep Holla <sudeep.holla@arm.com>; Mark Brown
><broonie@kernel.org>; ulf.hansson@linaro.org; lgirdwood@gmail.com;
>robh+dt@kernel.org; devicetree@vger.kernel.org; Hunter, Adrian
><adrian.hunter@intel.com>; michal.simek@xilinx.com; linux-
>mmc@vger.kernel.org; linux-kernel@vger.kernel.org; Shevchenko, Andriy
><andriy.shevchenko@intel.com>; A, Rashmi <rashmi.a@intel.com>; Vaidya,
>Mahesh R <mahesh.r.vaidya@intel.com>
>Subject: Re: [PATCH v1 5/9] firmware: keembay: Add support for Trusted
>Firmware Service call
>
>Hi
>
>sorry I'm a bit late on this.
>
>On Mon, Jan 18, 2021 at 10:28:33AM +0000, Zulkifli, Muhammad Husaini
>wrote:
>> Hi Sudeep and Mark,
>>
>> Thanks for the review. I replied inline.
>>
>> >-----Original Message-----
>> >From: Sudeep Holla <sudeep.holla@arm.com>
>> >Sent: Saturday, January 16, 2021 2:58 AM
>> >To: Mark Brown <broonie@kernel.org>
>> >Cc: Zulkifli, Muhammad Husaini <muhammad.husaini.zulkifli@intel.com>;
>> >ulf.hansson@linaro.org; lgirdwood@gmail.com; robh+dt@kernel.org;
>> >devicetree@vger.kernel.org; Hunter, Adrian <adrian.hunter@intel.com>;
>> >michal.simek@xilinx.com; linux-mmc@vger.kernel.org; linux-
>> >kernel@vger.kernel.org; Shevchenko, Andriy
>> ><andriy.shevchenko@intel.com>; A, Rashmi <rashmi.a@intel.com>;
>> >Vaidya, Mahesh R <mahesh.r.vaidya@intel.com>; Sudeep Holla
>> ><sudeep.holla@arm.com>
>> >Subject: Re: [PATCH v1 5/9] firmware: keembay: Add support for
>> >Trusted Firmware Service call
>> >
>> >On Thu, Jan 14, 2021 at 04:48:11PM +0000, Mark Brown wrote:
>> >> On Thu, Jan 14, 2021 at 11:26:56PM +0800, Muhammad Husaini Zulkifli
>> >wrote:
>> >> > Export inline function to encapsulate AON_CFG1 for controling the
>> >> > I/O Rail supplied voltage levels which communicate with Trusted
>Firmware.
>> >>
>> >> Adding Sudeep for the SMCCC bits, not deleting any context for his
>> >> benefit.
>> >>
>> >
>> >Thanks Mark for cc-ing me and joining the dots. I completely forgot
>> >about that fact that this platform was using SCMI using SMC as
>> >transport. Sorry for that and it is my fault. I did review the
>> >SCMI/SMC support for this platform sometime in June/July last year
>> >and forgot the fact it is same platform when voltage/regulator
>> >support patches for SD/MMC was posted sometime later last year. I
>concentrated on SMCCC conventions and other details.
>>
>> Yes Sudeep. I redesigned the way I handle the smccc call. Previously it was
>handled directly in mmc driver.
>> After few discussion, we conclude to create an abstraction using
>> regulator framework to encapsulate this smccc call during set voltage
>operation. Using standard abstraction will make things easier for the
>maintainer.
>>
>> >
>> >[...]
>> >
>> >> > +#define ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAGE
>	\
>> >> > +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,
>	\
>> >> > +			   ARM_SMCCC_SMC_32,		\
>> >> > +			   ARM_SMCCC_OWNER_SIP,		\
>> >> > +			   KEEMBAY_SET_SD_VOLTAGE_ID)
>> >> > +
>> >> > +#define ARM_SMCCC_SIP_KEEMBAY_GET_SD_VOLTAGE
>	\
>> >> > +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,
>	\
>> >> > +			   ARM_SMCCC_SMC_32,		\
>> >> > +			   ARM_SMCCC_OWNER_SIP,		\
>> >> > +			   KEEMBAY_GET_SD_VOLTAGE_ID)
>> >> > +
>> >> > +#define KEEMBAY_REG_NUM_CONSUMERS 2
>> >> > +
>> >> > +struct keembay_reg_supply {
>> >> > +	struct regulator *consumer;
>> >> > +};
>> >> > +
>> >> > +#if IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)
>> >> > +/*
>> >> > + * Voltage applied on the IO Rail is controlled from the Always
>> >> > +On Register using specific
>> >> > + * bits in AON_CGF1 register. This is a secure register. Keem
>> >> > +Bay SOC cannot exposed this
>> >> > + * register address to the outside world.
>> >> > + */
>> >> > +static inline int keembay_set_io_rail_supplied_voltage(int volt) {
>> >> > +	struct arm_smccc_res res;
>> >> > +
>> >> > +
>> >	arm_smccc_1_1_invoke(ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTA
>> >GE, volt,
>> >> > +&res);
>> >>
>> >> There is a SCMI voltage domain protocol intended for just this use
>> >> case of controlling regulators managed by the firmware, why are you
>> >> not using that for these systems?  See
>drivers/firmware/arm_scmi/voltage.c.
>>
>> From mmc maintainer's perspective, I should use the common modelling
>> either using regulator framework or pinctrl to perform voltage
>> operation. Not just directly invoke smccc call in the mmc driver. That
>> is why I came up with this regulator driver to perform voltage operation.
>>
>
>There is an SCMI regulator driver built on top of SCMIv3.0 Voltage Domain
>Protocol, so as long as your SCMI platform firmware support the new VD
>protocol you should be able to wire up a generic SCMI regulator in the DT
>(as described in the arm,scmi.txt bindings) and then just use the usual
>regulator framework ops with such SCMI regulator without the need to add
>a custom regulator using custom SMCCC calls).

I try to hook up the DT last night. Seems like the SCMI Protocol 17 is not implemented at ATF side.
Double check with ATF Team, currently we don't have SCMI voltage domain control in ARM Trusted Firmware yet
as of now, that is why even if I map the function to scmi, my call will be fail.

[    2.648989] arm-scmi firmware:scmi: SCMI Notifications - Core Enabled.
[    2.656157] arm-scmi firmware:scmi: SCMI Protocol v1.0 'INTEL:KMB' Firmware version 0x1
[    2.664513] arm-scmi firmware:scmi: SCMI protocol 23 not implemented
[    2.675898] arm-scmi firmware:scmi: SCMI protocol 17 not implemented

Any possibilities that for UHS patch we go with my current regulator driver implementation?

>
>Thanks
>
>Cristian
>
>> >>
>> >
>> >Indeed. Please switch to using the new voltage protocol added for this
>without
>> >any extra code. You just need to wire up DT for this.
>>
>> May I know even if I wire up the DT, how should I call this from the mmc
>driver
>> For set/get voltage operation? Any example?
>>
>> >
>> >Just for curiosity, where is SCMI platform firmware implemented ? On
>Cortex-
>> >A, secure side or external processor. Does this platform run TF-A ?
>>
>> The KMB SCMI framework is implemented in secure runtime firmware (TF-A
>BL31).
>> Hopefully I am answering your question.
>>
>> >
>> >--
>> >Regards,
>> >Sudeep