linux-kernel - Re: [PATCH V8 5/6] ACPI: Support the probing on the devices which apply indirect-IO

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Message-ID: <bfdf2de0-c309-0139-4075-dfcd678b6d51@gmail.com>
Date:   Sat, 1 Apr 2017 10:16:53 +0800
From:   "zhichang.yuan" <zhichang.yuan02@...il.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "zhichang.yuan" <yuanzhichang@...ilicon.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Mark Rutland <mark.rutland@....com>,
        Brian Starkey <brian.starkey@....com>,
        Olof Johansson <olof@...om.net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        linuxarm@...wei.com,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Corey Minyard <minyard@....org>,
        Zou Rongrong <zourongrong@...il.com>,
        John Garry <john.garry@...wei.com>,
        Gabriele Paoloni <gabriele.paoloni@...wei.com>,
        kantyzc@....com, xuwei5@...ilicon.com
Subject: Re: [PATCH V8 5/6] ACPI: Support the probing on the devices which
 apply indirect-IO



On 04/01/2017 07:02 AM, Rafael J. Wysocki wrote:
> On Fri, Mar 31, 2017 at 8:52 AM, zhichang.yuan
> <yuanzhichang@...ilicon.com> wrote:
>> Hi, Rafael,
>>
>> Thanks for reviewing this!
>>
>> On 2017/3/31 4:31, Rafael J. Wysocki wrote:
>>> 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?
>>
>> As you know currently for ARM architecture IO space is memory mapped and
>> is only used by pci devices. The port number is dynamically allocated
>> converting the device IO address into a PIO token: i.e.
>> http://lxr.free-electrons.com/source/drivers/acpi/pci_root.c#L745
>> This patch is meant to support a new class of IO host controller
>> that are not PCI based and that still require to have the IO addresses
>> be translated in the same PIO token space as the PCI controller
> 
> IOW, this is ARM-specific, right?

Yes. The current host added in this patch with _HID "HISI0191" is on ARM64.
But, I think the handler driver is architecture dependent.

Thanks,
Zhichang

> 
> Thanks,
> Rafael
>