linux-kernel - Re: [PATCH v4 03/15] drivers: acpi: iort: introduce linker section for IORT entries probing

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Date:   Mon, 5 Sep 2016 19:42:05 +0800
From:   Hanjun Guo <hanjun.guo@...aro.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        iommu@...ts.linux-foundation.org
Cc:     Tomasz Nowicki <tn@...ihalf.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will.deacon@....com>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>, Jon Masters <jcm@...hat.com>,
        Sinan Kaya <okaya@...eaurora.org>,
        Nate Watterson <nwatters@...eaurora.org>,
        Dennis Chen <dennis.chen@....com>, linux-acpi@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 03/15] drivers: acpi: iort: introduce linker section
 for IORT entries probing

On 2016/8/15 23:23, Lorenzo Pieralisi wrote:
> Since commit e647b532275b ("ACPI: Add early device probing
> infrastructure") the kernel has gained the infrastructure that allows
> adding linker script section entries to execute ACPI driver callbacks
> (ie probe routines) for all subsystems that register a table entry
> in the respective kernel section (eg clocksource, irqchip).
>
> Since ARM IOMMU devices data is described through IORT tables when
> booting with ACPI, the ARM IOMMU drivers must be made able to hook ACPI
> callback routines that are called to probe IORT entries and initialize
> the respective IOMMU devices.
>
> To avoid adding driver specific hooks into IORT table initialization
> code (breaking therefore code modularity - ie ACPI IORT code must be made
> aware of ARM SMMU drivers ACPI init callbacks), this patch adds code
> that allows ARM SMMU drivers to take advantage of the ACPI early probing
> infrastructure, so that they can add linker script section entries
> containing drivers callback to be executed on IORT tables detection.
>
> Since IORT nodes are differentiated by a type, the callback routines
> can easily parse the IORT table entries, check the IORT nodes and
> carry out some actions whenever the IORT node type associated with
> the driver specific callback is matched.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Tomasz Nowicki <tn@...ihalf.com>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Marc Zyngier <marc.zyngier@....com>
> ---
>  drivers/acpi/arm64/iort.c         | 2 ++
>  include/asm-generic/vmlinux.lds.h | 1 +
>  include/linux/iort.h              | 3 +++
>  3 files changed, 6 insertions(+)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 2543f60..cad7d1d 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -383,4 +383,6 @@ void __init iort_table_detect(void)
>  		const char *msg = acpi_format_exception(status);
>  		pr_err("Failed to get table, %s\n", msg);
>  	}
> +
> +	acpi_probe_device_table(iort);
>  }
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 2456397..7ee4e0c 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -546,6 +546,7 @@
>  	IRQCHIP_OF_MATCH_TABLE()					\
>  	ACPI_PROBE_TABLE(irqchip)					\
>  	ACPI_PROBE_TABLE(clksrc)					\
> +	ACPI_PROBE_TABLE(iort)						\
>  	EARLYCON_TABLE()
>
>  #define INIT_TEXT							\
> diff --git a/include/linux/iort.h b/include/linux/iort.h
> index d7daba1..9bb30c5 100644
> --- a/include/linux/iort.h
> +++ b/include/linux/iort.h
> @@ -38,4 +38,7 @@ static inline struct irq_domain *
>  iort_get_device_domain(struct device *dev, u32 req_id) { return NULL; }
>  #endif
>
> +#define IORT_ACPI_DECLARE(name, table_id, fn)		\
> +	ACPI_DECLARE_PROBE_ENTRY(iort, name, table_id, 0, NULL, 0, fn)
> +
>  #endif /* __IORT_H__ */

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

Thanks
Hanjun