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

[Bin Meng]

Hi Simon,

On Wed, Nov 27, 2019 at 11:42 AM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Heinrich,
>
> On Mon, 25 Nov 2019 at 18:12, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >
> > 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>
> > >>> *抄送:* xypron.glpk at gmx.de <xypron.glpk at gmx.de>; liuhao at phytium.com.cn
> > >>> <liuhao at phytium.com.cn>; agraf at csgraf.de <agraf at csgraf.de>;
> > >>> jagan at amarulasolutions.com <jagan at amarulasolutions.com>;
> > >>> marek.vasut at gmail.com <marek.vasut at gmail.com>; sr at denx.de <sr at denx.de>;
> > >>> patrice.chotard at st.com <patrice.chotard at st.com>; afd at ti.com
> > >>> <afd at ti.com>; horatiu.vultur at microchip.com
> > >>> <horatiu.vultur at microchip.com>; narmstrong at baylibre.com
> > >>> <narmstrong at baylibre.com>; ryder.lee at mediatek.com
> > >>> <ryder.lee at mediatek.com>; igor.opaniuk at gmail.com
> > >>> <igor.opaniuk at gmail.com>; patrick.delaunay at st.com
> > >>> <patrick.delaunay at st.com>; eugen.hristev at microchip.com
> > >>> <eugen.hristev at microchip.com>; sjg at chromium.org <sjg at chromium.org>;
> > >>> judge.packham at gmail.com <judge.packham at gmail.com>;
> > >>> yamada.masahiro at socionext.com <yamada.masahiro at socionext.com>;
> > >>> swarren at nvidia.com <swarren at nvidia.com>; michal.simek at xilinx.com
> > >>> <michal.simek at xilinx.com>; u-boot at lists.denx.de <u-boot at lists.denx.de>;
> > >>> 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?
>
> Yes that's my goal, except that some tables are generated wholesale
> from code (equivalent to entire nodes in DT).
>
> I had a bit of a look at how this is done in coreboot. It is pretty
> hard to follow as there are weak functions and the code jumps back and
> forth between generic code and SoC-specific code. But every device has
> ACPI operation and I think that makes sense.
>
> My current idea is to add a new optional acpi_ops struct pointer into
> each struct driver, to handle the ACPI table generation and other
> things needed by ACPI. Then devices that want to do ACPI things can do
> so. Then we need a new drivers/core/acpi.c file to handle things.
>

Yes, this approach makes sense to me, for dynamic ACPI table generation.

Regards,
Bin