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

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Date:   Mon, 18 Nov 2019 13:57:59 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     "Andrew F. Davis" <afd@...com>
Cc:     linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: OMAP: Use ARM SMC Calling Convention when OP-TEE is
 available

Hi,

* Andrew F. Davis <afd@...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.

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

AFAIK this should work both for optee and the current use cases.

Regards,

Tony