From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: "zhichang.yuan" <yuanzhichang@hisilicon.com>
Cc: catalin.marinas@arm.com, will.deacon@arm.com, robh+dt@kernel.org,
        frowand.list@gmail.com, bhelgaas@google.com, rafael@kernel.org,
        arnd@arndb.de, linux-arm-kernel@lists.infradead.org,
        mark.rutland@arm.com, brian.starkey@arm.com, olof@lixom.net,
        lorenzo.pieralisi@arm.com, benh@kernel.crashing.org,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        linuxarm@huawei.com, devicetree@vger.kernel.org,
        linux-pci@vger.kernel.org, minyard@acm.org, zourongrong@gmail.com,
        john.garry@huawei.com, gabriele.paoloni@huawei.com,
        zhichang.yuan02@gmail.com, kantyzc@163.com, xuwei5@hisilicon.com
Subject: Re: [PATCH V8 5/6] ACPI: Support the probing on the devices which apply  indirect-IO
Date: Thu, 30 Mar 2017 22:31:10 +0200
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On Thursday, March 30, 2017 11:26:58 PM zhichang.yuan wrote:
> On some platforms(such as Hip06/Hip07), the legacy ISA/LPC devices access I/O
> with some special host-local I/O ports known on x86. To access the I/O
> peripherals, an indirect-IO mechanism is introduced to mapped the host-local
> I/O to system logical/fake PIO similar the PCI MMIO on architectures where no
> separate I/O space exists. Just as PCI MMIO, the host I/O range should be
> registered before probing the downstream devices and set up the I/O mapping.
> But current ACPI bus probing doesn't support these indirect-IO hosts/devices.
> 
> This patch introdueces a new ACPI handler for this device category. Through the
> handler attach callback, the indirect-IO hosts I/O registration is done and
> all peripherals' I/O resources are translated into logic/fake PIO before
> starting the enumeration.

Can you explain to me briefly what exactly this code is expected to be doing?

Thanks,
Rafael