[U-Boot] [PATCH v2] serial: ns16550: Add register shift variable

[Lokesh Vutla]

On Tuesday 17 July 2018 02:42 PM, Alexander Graf wrote:
> On 07/17/2018 09:55 AM, Lokesh Vutla wrote:
>>
>> On Tuesday 17 July 2018 12:32 PM, Felix Brack wrote:
>>> This patch adds a new Kconfig variable that allows setting
>>> the register offset shift value for the ns16550 driver to some
>>> other value then 0 if not defined by the DT. All credit for this
>>> patch goes to Lokesh Vutla as it was his idea.
>>>
>>> The motivation for writing this patch originates in the
>>> effort of synchronizing U-Boot DT to Linux DT for am33xx SOCs.
>>> The current am33xx.dtsi file from U-Boot defines the <reg-shift>
>>> property for all UART nodes. The actual (4.18+) am33xx.dtsi
>>> file from Linux does not define <reg-shift> anymore. To prevent
>>> (probably difficult) changes in many .dts and .dtsi files once
>>> the synchronization is done, one can use this new variable. For
>>> the pdu001 board, for example, SYS_NS16550_REG_SHIFT is set
>>> to 2; no need to clutter U-Boot and board specific dts files
>>> with <reg-shift> properties.
>>>
>>> Signed-off-by: Felix Brack <fb at ltec.ch>
> 
> NAK. Please determine the shift value from the compatible instead.
> Ideally you would create a subclass of the ns16550 device class and set
> reg_shift in there.

There was a separate driver for omap_serial initially but was deleted by
the below commit:

commit c7b9686d5d482c8e952598841ea467e6ec0ec0de
Author: Thomas Chou <thomas at wytron.com.tw>
Date:   Thu Nov 19 21:48:12 2015 +0800

    ns16550: unify serial_omap

    Unify serial_omap, and use the generic binding.

    Signed-off-by: Thomas Chou <thomas at wytron.com.tw>
    Reviewed-by: Tom Rini <trini at konsulko.com>
    Acked-by: Simon Glass <sjg at chromium.org>


Thanks and regards,
Lokesh