[U-Boot] [PATCH v3] arm: add acpi support for the arm

[Heinrich Schuchardt]

On 11/26/19 12:40 AM, Simon Glass wrote:
> Hi,
>
> On Mon, 25 Nov 2019 at 15:57, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>>
>> On 11/25/19 3:42 AM, Steven Hao wrote:> 获取 Outlook for iOS
>> <https://aka.ms/o0ukef>
>>> ------------------------------------------------------------------------
>>> *发件人:* Bin Meng <bmeng.cn at gmail.com>
>>> *发送时间:* Monday, November 25, 2019 10:13:40 AM
>>> *收件人:* Steven Hao <steven_hao5189 at outlook.com>
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>>> Andy Shevchenko <andriy.shevchenko at linux.intel.com>
>>> *主题:* Re: [PATCH v3] arm: add acpi support for the arm
>>> Hi Steven,
>>>
>>> On Mon, Nov 25, 2019 at 10:09 AM Steven Hao <steven_hao5189 at outlook.com>
>>> wrote:
>>>>
>>>> Dear Bin：
>>>>
>>>> Firstly：
>>>> I know that acpi about x86 is existing. And it is usefull for x86
>> platfporm. If it  is used to arm platform，some modification may have to
>> do. For example，facs table is useless for arm.
>>>>
>>>> In adition，The acpi table is writed statically and then modified
>> dynamically in my patch. It is a new method.
>>>>
>>>> I want to consult that whether my method is helpful or not.
>>>>
>>>> Secondly：
>>>> If i want to reuse the x86-acpi. I will overwrite the
>> write_acpi_tables function. But the definition about acpi strcuture is
>> placed in arch/x86/include/asm directory. It can not be used to arm
>> plateform. If the acpi library need to surport for all platform，i  think
>> it should move to /include directory.
>>>>
>>>
>>> Yes, we all are aware that modifications are needed to the existing
>>> x86 ACPI support to support ARM. We don't want to create 2 ACP
>>> implementation in U-Boot.
>>>
>>> Regards,
>>> Bin> Dear Bin：
>>>
>>> I have a suggetion that the acpi specification definition such as all
>>> acpi table structure definition  should be place in /include directory.
>>> and write_acpi_tables function can be placed in platform directory.
>>>    Creating acpi table mothod  can be diffrent between x86 and arm.
>>>
>>> Thank you
>>> Steven Hao
>>>
>>
>> Currently we are using CPU specific C files generating ACPI tables, e.g.
>> arch/x86/cpu/tangier/acpi.c.
>>
>> I would prefer if we would generate the ACPI tables and definition
>> blocks completely from text files instead of using C code. This would
>> avoid any architecture specific code.
>
> I am finding with Apollo Lake that this isn't possible - we need to
> insert run-time information into the tables set up with .asl files.

For device trees we generate the binary form with a compiler. Then we
patch the device tree with runtime information in image_setup_libfdt().

Couldn't we go a similar way for ACPI?

Best regards

Heinrich

>
>>
>> Such table generation is already in use in the Windows world. See:
>> https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/generate-acpi-tables-by-using-acpigenfx
>
> That looks like a programmatic way to create ACPI tables. If so, I'm
> trying to bring something similar over from coreboot.
>
> Regards,
> Simon
>