linux-kernel - Re: [PATCH 16/17] arm64: arch_timer: Allow erratum matching with ACPI OEM information

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Date:   Tue, 7 Mar 2017 21:12:26 +0800
From:   Hanjun Guo <hanjun.guo@...aro.org>
To:     Marc Zyngier <marc.zyngier@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Scott Wood <oss@...error.net>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Ding Tianhong <dingtianhong@...wei.com>
Subject: Re: [PATCH 16/17] arm64: arch_timer: Allow erratum matching with ACPI
 OEM information



On 2017/3/6 19:26, Marc Zyngier wrote:
> Just as we're able to identify a broken platform using some DT
> information, let's enable a way to spot the offenders with ACPI.
>
> The difference is that we can only match on some OEM info instead
> of implementation-specific properties. So in order to avoid the
> insane multiplication of errata structures, we allow an array
> of OEM descriptions to be attached to an erratum structure.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  arch/arm64/include/asm/arch_timer.h  |  1 +
>  drivers/clocksource/arm_arch_timer.c | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
>
> diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
> index 159513479f6e..2e635deba776 100644
> --- a/arch/arm64/include/asm/arch_timer.h
> +++ b/arch/arm64/include/asm/arch_timer.h
> @@ -42,6 +42,7 @@ enum arch_timer_erratum_match_type {
>  	ate_match_dt,
>  	ate_match_global_cap_id,
>  	ate_match_local_cap_id,
> +	ate_match_acpi_oem_info,
>  };
>
>  struct clock_event_device;
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 4eb1109da330..6182871af4eb 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -190,6 +190,12 @@ static struct cyclecounter cyclecounter __ro_after_init = {
>  	.mask	= CLOCKSOURCE_MASK(56),
>  };
>
> +struct ate_acpi_oem_info {
> +	char oem_id[ACPI_OEM_ID_SIZE + 1];
> +	char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
> +	u32 oem_revision;
> +};
> +
>  #ifdef CONFIG_FSL_ERRATUM_A008585
>  /*
>   * The number of retries is an arbitrary value well beyond the highest number
> @@ -378,6 +384,28 @@ bool arch_timer_check_local_cap_erratum(const struct arch_timer_erratum_workarou
>  	return this_cpu_has_cap((uintptr_t)wa->id);
>  }
>
> +
> +static
> +bool arch_timer_check_acpi_oem_erratum(const struct arch_timer_erratum_workaround *wa,
> +				       const void *arg)
> +{
> +	static const struct ate_acpi_oem_info empty_oem_info = {};
> +	const struct ate_acpi_oem_info *info = wa->id;
> +	const struct acpi_table_header *table = arg;
> +
> +	/* Iterate over the ACPI EOM info array, looking for a match */

typo, 'OEM'.

> +	while (memcmp(info, &empty_oem_info, sizeof(*info))) {
> +		if (!memcmp(info->oem_id, table->oem_id, ACPI_OEM_ID_SIZE) &&
> +		    !memcmp(info->oem_table_id, table->oem_table_id, ACPI_OEM_TABLE_ID_SIZE) &&
> +		    info->oem_revision == table->oem_revision)
> +			return true;
> +
> +		info++;
> +	}
> +
> +	return false;
> +}
> +
>  static const struct arch_timer_erratum_workaround *
>  arch_timer_iterate_errata(enum arch_timer_erratum_match_type type,
>  			  ate_match_fn_t match_fn,
> @@ -441,6 +469,9 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
>  		match_fn = arch_timer_check_local_cap_erratum;
>  		local = true;
>  		break;
> +	case ate_match_acpi_oem_info:
> +		match_fn = arch_timer_check_acpi_oem_erratum;
> +		break;
>  	}
>
>  	wa = arch_timer_iterate_errata(type, match_fn, arg);
> @@ -1284,6 +1315,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
>
>  	/* Check for globally applicable workarounds */
>  	arch_timer_check_ool_workaround(ate_match_global_cap_id, NULL);
> +	arch_timer_check_ool_workaround(ate_match_acpi_oem_info, table);
>
>  	arch_timer_init();
>  	return 0;

Reviewed-by: Hanjun Guo <hanjun.guo@...aro.org>

Thanks
Hanjun