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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Thu, 10 Nov 2016 00:37:04 +0100
Message-ID: <CAJZ5v0iRwh3T8U6JeDgWSMX4hbuvo21KGh7MV__=DCVMMefsTQ@mail.gmail.com>
Subject: Re: [PATCH v7 01/16] drivers: acpi: add FWNODE_ACPI_STATIC fwnode type
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: "open list:AMD IOMMU (AMD-VI)" <iommu@lists.linux-foundation.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Will Deacon <will.deacon@arm.com>, Marc Zyngier <marc.zyngier@arm.com>,
        Robin Murphy <robin.murphy@arm.com>, Joerg Roedel <joro@8bytes.org>,
        Tomasz Nowicki <tn@semihalf.com>, Hanjun Guo <hanjun.guo@linaro.org>,
        Jon Masters <jcm@redhat.com>, Eric Auger <eric.auger@redhat.com>,
        Sinan Kaya <okaya@codeaurora.org>,
        Nate Watterson <nwatters@codeaurora.org>,
        Prem Mallappa <prem.mallappa@broadcom.com>,
        Dennis Chen <dennis.chen@arm.com>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux PCI <linux-pci@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
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On Wed, Nov 9, 2016 at 3:19 PM, Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> wrote:
> On systems booting with a device tree, every struct device is associated
> with a struct device_node, that provides its DT firmware representation.
> The device node can be used in generic kernel contexts (eg IRQ
> translation, IOMMU streamid mapping), to retrieve the properties
> associated with the device and carry out kernel operations accordingly.
> Owing to the 1:1 relationship between the device and its device_node,
> the device_node can also be used as a look-up token for the device (eg
> looking up a device through its device_node), to retrieve the device in
> kernel paths where the device_node is available.
>
> On systems booting with ACPI, the same abstraction provided by
> the device_node is required to provide look-up functionality.
>
> The struct acpi_device, that represents firmware objects in the
> ACPI namespace already includes a struct fwnode_handle of
> type FWNODE_ACPI as their member; the same abstraction is missing
> though for devices that are instantiated out of static ACPI tables
> entries (eg ARM SMMU devices).
>
> Add a new fwnode_handle type to associate devices created out
> of static ACPI table entries to the respective firmware components
> and create a simple ACPI core layer interface to dynamically allocate
> and free the corresponding firmware nodes so that kernel subsystems
> can use it to instantiate the nodes and associate them with the
> respective devices.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
> Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
> Tested-by: Tomasz Nowicki <tn@semihalf.com>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Thanks!