Re: [PATCH] ARM: OMAP: Use ARM SMC Calling Convention when OP-TEE is available

Andrew F. Davis
2019-11-18T22:13:52Z

On 11/18/19 4:57 PM, Tony Lindgren wrote:
> Hi,
>
> * Andrew F. Davis <afd@ti.com> [191118 08:53]:
>> +#define OMAP_SIP_SMC_STD_CALL_VAL(func_num) \
>> + ARM_SMCCC_CALL_VAL(ARM_SMCCC_STD_CALL, ARM_SMCCC_SMC_32, \
>> + ARM_SMCCC_OWNER_SIP, (func_num))
>> +
>> +void omap_smc1(u32 fn, u32 arg)
>> +{
>> + struct device_node *optee;
>> + struct arm_smccc_res res;
>> +
>> + /*
>> + * If this platform has OP-TEE installed we use ARM SMC calls
>> + * otherwise fall back to the OMAP ROM style calls.
>> + */
>> + optee = of_find_node_by_path("/firmware/optee");
>> + if (optee) {
>> + arm_smccc_smc(OMAP_SIP_SMC_STD_CALL_VAL(fn), arg,
>> + 0, 0, 0, 0, 0, 0, &res);
>> + WARN(res.a0, "Secure function call 0x%08x failed\n", fn);
>> + } else {
>> + _omap_smc1(fn, arg);
>> + }
>> +}
>
> I think we're better off just making arm_smccc_smc() work properly.
> See cat arch/arm*/kernel/smccc-call.S.
>

arm_smccc_smc() does work properly already, I'm using it here.

> If quirk handling is needed, looks like ARM_SMCCC_QUIRK_STATE_OFFS
> can be used.
>

Tried that [0], was NAKd. Making quirk-free SMCCC calls if OP-TEE is
detected seems to be the suggested path forward, QCOM got a pass,
doesn't look like we will get the same.

+Mark, in case you want to comment if this patch matches what you had in
mind.

[0] https://www.spinics.net/lists/arm-kernel/msg607263.html

Andrew

> AFAIK this should work both for optee and the current use cases.
>
> Regards,
>
> Tony
>