[U-Boot] [PATCH v2 2/7] serial: Allow boards to determine whether a serial device is usable

[Alexander Graf <agraf@suse.de>]

On 17.01.18 23:11, Simon Glass wrote:
> Hi Alex,
> 
> On 17 January 2018 at 15:03, Alexander Graf <agraf@suse.de> wrote:
>>
>>
>> On 17.01.18 20:39, Simon Glass wrote:
>>> Hi Alex,
>>>
>>> On 17 January 2018 at 00:54, Alexander Graf <agraf@suse.de> wrote:
>>>> On some boards, serial devices may or may not be muxed properly to actual
>>>> pins, depending on firmware configuration. To determine whether we should
>>>> use a serial device for U-Boot in-/output, we need to check whether it
>>>> is muxed properly.
>>>>
>>>> This is something only the board file can do, so let's expose a weak
>>>> function that a board can override to explicitly allow or disallow
>>>> usage of certain serial devices.
>>>>
>>>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>>> ---
>>>>  drivers/serial/serial-uclass.c | 11 +++++++++++
>>>>  include/serial.h               | 11 +++++++++++
>>>>  2 files changed, 22 insertions(+)
>>>>
>>>
>>> Can we please figure out how handle this in the serial driver / driver
>>> model itself? I want to avoid weak functions with driver model.
>>
>> I'm very happy to see suggestions :). The reason I went with the weak
>> function is really because I couldn't think of anything better.
> 
> The serial driver is proprietary so you should be able to put a call
> into the pinctrl driver from that. The pinctrl driver can return the
> state of a pin - maybe get_gpio_mux() or a new pinmux_get()?

The SoC has 2 serial drivers: a proprietary one and a pl011. Would you
think it's ok to put an architecture specific hack into the generic
pl011 code with an #ifdef?


Alex