[U-Boot] [PATCH 06/13] log: Add an implemention of logging

[Bin Meng]

Hi Simon,

On Wed, Sep 20, 2017 at 9:50 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 17 September 2017 at 21:45, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Simon,
>>
>> On Sun, Sep 17, 2017 at 5:23 AM, Simon Glass <sjg at chromium.org> wrote:
>>> Add the logging header file and implementation with some configuration
>>> options to control it.
>>>
>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>> ---
>>>
>>>  MAINTAINERS                       |   9 ++
>>>  common/Kconfig                    |  56 +++++++++
>>>  common/Makefile                   |   1 +
>>>  common/log.c                      | 246 +++++++++++++++++++++++++++++++++++++
>>>  include/asm-generic/global_data.h |   5 +
>>>  include/log.h                     | 247 ++++++++++++++++++++++++++++++++++++--
>>>  6 files changed, 555 insertions(+), 9 deletions(-)
>>>  create mode 100644 common/log.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 04acf2b89d..eb420afa8d 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -290,6 +290,15 @@ S: Maintained
>>>  T:     git git://git.denx.de/u-boot-i2c.git
>>>  F:     drivers/i2c/
>>>
>>> +LOGGING
>>> +M:     Simon Glass <sjg at chromium.org>
>>> +S:     Maintained
>>> +T:     git git://git.denx.de/u-boot.git
>>> +F:     common/log.c
>>> +F:     cmd/log.c
>>> +F:     test/log/log_test.c
>>> +F:     test/py/tests/test_log.py
>>
>> test/log/log_test.c and test/py/tests/test_log.py have not been
>> introduced at this point.
>
> OK I can tweak that,
> [..]
>
>>> +/**
>>> + * struct log_driver - a driver which accepts and processes log records
>>> + *
>>> + * @name: Name of driver
>>> + */
>>> +struct log_driver {
>>> +       const char *name;
>>> +       /**
>>> +        * emit() - emit a log record
>>> +        *
>>> +        * Called by the log system to pass a log record to a particular driver
>>> +        * for processing. The filter is checked before calling this function.
>>> +        */
>>> +       int (*emit)(struct log_device *ldev, struct log_rec *rec);
>>> +};
>>> +
>>
>> So we are creating a new type of non-DM driver which is log-specific?
>> How about we add this emit to the existing uclass driver that can be
>> used as the log driver? (eg: blk devices with file system?)
>
> Yes that's right. I think I can link it to DM once it starts up, but a
> logging of DM start-up is useful.
>
> Re your idea are you saying add an emit() method to UCLASS_BLK?
>

Yep, something like

#ifdef CONFIG_LOG
    .log_emit = xxx_log_emit,
#endif

Probably we need a flag to find out which driver provides such log
functionality.

Regards,
Bin