linux-kernel - Re: [RFC v2 3/4] ACPI: DBG2: add 16550 UART with 32-bit access

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Message-ID: <CAJZ5v0gnMb=eEJ1c_mWZyRvy6xNZxx=_E78D0fksKJTWwGKGLg@mail.gmail.com>
Date:   Tue, 6 Dec 2016 22:19:06 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Jon Masters <jcm@...hat.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Aleksey Makarov <aleksey.makarov@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Russell King <linux@....linux.org.uk>,
        Peter Hurley <peter@...leysoftware.com>,
        Mark Salter <msalter@...hat.com>, Duc Dang <dhdang@....com>,
        Rob Herring <robh@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Lv Zheng <lv.zheng@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>,
        "devel@...ica.org" <devel@...ica.org>
Subject: Re: [RFC v2 3/4] ACPI: DBG2: add 16550 UART with 32-bit access

On Tue, Dec 6, 2016 at 10:15 PM, Jon Masters <jcm@...hat.com> wrote:
> Quick note - specifically, Rafael, this is not currently part of the SPCR specification and
> should not be considered for inclusion in Linux until that is decided. Once it is determined
> what the fix for SPCR is, that should then be driven into the component architecture and
> proposed here.

OK, good to know, thanks!


> --
> Computer Architect | Sent from my 64-bit #ARM Powered phone
>
>> On Dec 6, 2016, at 16:00, Rafael J. Wysocki <rafael@...nel.org> wrote:
>>
>> On Tue, Dec 6, 2016 at 6:58 PM, Aleksey Makarov
>> <aleksey.makarov@...aro.org> wrote:
>>> It was suggested to add a new Microsoft Debug Port Table 2
>>> (DBG2) (the table used to enumerate the various subtypes of serial
>>> port covered by the SPCR) 16550 UART subtype that may be needed for
>>> some additional platforms, such as those based upon AppliedMicro
>>> X-Gene ARMv8 SoCs.  This new subtype would be 16550-compatible
>>> with 32-bit access.  There already exists 32-bit variant
>>> ACPI_DBG2_ARM_SBSA_32BIT of SBSA console ACPI_DBG2_ARM_SBSA_GENERIC.
>>>
>>> This patch introduces it to Linux kernel.
>>>
>>> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
>>> ---
>>> include/acpi/actbl2.h | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/include/acpi/actbl2.h b/include/acpi/actbl2.h
>>> index c93dbad..f219b04 100644
>>> --- a/include/acpi/actbl2.h
>>> +++ b/include/acpi/actbl2.h
>>> @@ -371,6 +371,7 @@ struct acpi_dbg2_device {
>>>
>>> #define ACPI_DBG2_16550_COMPATIBLE  0x0000
>>> #define ACPI_DBG2_16550_SUBSET      0x0001
>>> +#define ACPI_DBG2_16550_32BIT       0x0002
>>> #define ACPI_DBG2_ARM_PL011         0x0003
>>> #define ACPI_DBG2_ARM_SBSA_32BIT    0x000D
>>> #define ACPI_DBG2_ARM_SBSA_GENERIC  0x000E
>>> --
>>
>> This is an ACPICA change and it first needs to be made to the upstream
>> ACPICA code base.
>>
>> Thanks,
>> Rafael