linux-kernel - Re: [PATCH v2 12/16] firmware/psci: Expose PSCI conduit

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Message-ID: <20180129175523.GA24577@e107981-ln.cambridge.arm.com>
Date:   Mon, 29 Jan 2018 17:55:23 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Peter Maydell <peter.maydell@...aro.org>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Robin Murphy <robin.murphy@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jon Masters <jcm@...hat.com>
Subject: Re: [PATCH v2 12/16] firmware/psci: Expose PSCI conduit

On Mon, Jan 29, 2018 at 05:45:55PM +0000, Marc Zyngier wrote:
> In order to call into the firmware to apply workarounds, it is
> useful to find out whether we're using HVC or SMC. Let's expose
> this through the psci_ops.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  drivers/firmware/psci.c | 28 +++++++++++++++++++++++-----
>  include/linux/psci.h    |  7 +++++++
>  2 files changed, 30 insertions(+), 5 deletions(-)

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>

> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index 8b25d31e8401..e9493da2b111 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -59,7 +59,9 @@ bool psci_tos_resident_on(int cpu)
>  	return cpu == resident_cpu;
>  }
>  
> -struct psci_operations psci_ops;
> +struct psci_operations psci_ops = {
> +	.conduit = PSCI_CONDUIT_NONE,
> +};
>  
>  typedef unsigned long (psci_fn)(unsigned long, unsigned long,
>  				unsigned long, unsigned long);
> @@ -210,6 +212,22 @@ static unsigned long psci_migrate_info_up_cpu(void)
>  			      0, 0, 0);
>  }
>  
> +static void set_conduit(enum psci_conduit conduit)
> +{
> +	switch (conduit) {
> +	case PSCI_CONDUIT_HVC:
> +		invoke_psci_fn = __invoke_psci_fn_hvc;
> +		break;
> +	case PSCI_CONDUIT_SMC:
> +		invoke_psci_fn = __invoke_psci_fn_smc;
> +		break;
> +	default:
> +		WARN(1, "Unexpected PSCI conduit %d\n", conduit);
> +	}
> +
> +	psci_ops.conduit = conduit;
> +}
> +
>  static int get_set_conduit_method(struct device_node *np)
>  {
>  	const char *method;
> @@ -222,9 +240,9 @@ static int get_set_conduit_method(struct device_node *np)
>  	}
>  
>  	if (!strcmp("hvc", method)) {
> -		invoke_psci_fn = __invoke_psci_fn_hvc;
> +		set_conduit(PSCI_CONDUIT_HVC);
>  	} else if (!strcmp("smc", method)) {
> -		invoke_psci_fn = __invoke_psci_fn_smc;
> +		set_conduit(PSCI_CONDUIT_SMC);
>  	} else {
>  		pr_warn("invalid \"method\" property: %s\n", method);
>  		return -EINVAL;
> @@ -654,9 +672,9 @@ int __init psci_acpi_init(void)
>  	pr_info("probing for conduit method from ACPI.\n");
>  
>  	if (acpi_psci_use_hvc())
> -		invoke_psci_fn = __invoke_psci_fn_hvc;
> +		set_conduit(PSCI_CONDUIT_HVC);
>  	else
> -		invoke_psci_fn = __invoke_psci_fn_smc;
> +		set_conduit(PSCI_CONDUIT_SMC);
>  
>  	return psci_probe();
>  }
> diff --git a/include/linux/psci.h b/include/linux/psci.h
> index f724fd8c78e8..f2679e5faa4f 100644
> --- a/include/linux/psci.h
> +++ b/include/linux/psci.h
> @@ -25,6 +25,12 @@ bool psci_tos_resident_on(int cpu);
>  int psci_cpu_init_idle(unsigned int cpu);
>  int psci_cpu_suspend_enter(unsigned long index);
>  
> +enum psci_conduit {
> +	PSCI_CONDUIT_NONE,
> +	PSCI_CONDUIT_SMC,
> +	PSCI_CONDUIT_HVC,
> +};
> +
>  struct psci_operations {
>  	u32 (*get_version)(void);
>  	int (*cpu_suspend)(u32 state, unsigned long entry_point);
> @@ -34,6 +40,7 @@ struct psci_operations {
>  	int (*affinity_info)(unsigned long target_affinity,
>  			unsigned long lowest_affinity_level);
>  	int (*migrate_info_type)(void);
> +	enum psci_conduit conduit;
>  };
>  
>  extern struct psci_operations psci_ops;
> -- 
> 2.14.2
>