[S] Change in flashrom[main]: how_to_add_new_chip: Add a section for feature bits and WRSR handling

[Hsuan-ting Chen (Code Review)]

Attention is currently required from: Anastasia Klimchuk, Hsuan Ting Chen, Thomas Heijligen.

Hsuan-ting Chen has posted comments on this change by Hsuan-ting Chen. ( https://review.coreboot.org/c/flashrom/+/82908?usp=email )

Change subject: how_to_add_new_chip: Add a section for feature bits and WRSR handling
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Patch Set 1:

(1 comment)

File doc/contrib_howtos/how_to_add_new_chip.rst:

https://review.coreboot.org/c/flashrom/+/82908/comment/e28d2514_615354ec?usp... :
PS1, Line 110: 
             : Write-Status-Register (WRSR) Handling
             : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
             : 
             : ``FEATURE_WRSR_EWSR``, ``FEATURE_WRSR_WREN``, and ``FEATURE_WRSR_EITHER``. These bits used for **SPI only**.
             : 
             : The Write Status Register (WRSR) is used to configure various settings within the flash chip, including write protection and
             : other features. The way WRSR is accessed varies between SPI flash chips, leading to the need for these feature bits.
             : 
             : * ``FEATURE_WRSR_EWSR``:
             :   This indicates that we need an **Enable-Write-Status-Register** (EWSR) instruction which opens the status register for the
             :   immediately-followed next WRSR instruction. Usually, the opcode is **0x50**.
             : 
             : * ``FEATURE_WRSR_WREN``:
             :   This indicates that we need an **Write-Enable** (WREN) instruction to set the Write Enable Latch (WEL) bit. The WEL bit
             :   must be set priort to every WRSR command. Usually, the opcode is **0x06**.
             : 
             : * ``FEATURE_WRSR_EITHER``:
             :   This indicates that either EWSR or WREN is supported in this chip.
> Maybe move this section to "Write-protection" , below? You can skip the intro, and rename the sectio […]

Hi Anastasia:

Thanks for the review!

1. We had an in-depth discussion while adding  [GD25LQ255E](https://review.coreboot.org/c/flashrom/+/79088/comment/a8af90df_8fdf85cb/) where it took us some time to grasp the meaning of `FEATURE_WRSR_EXT2` and `FEATURE_WRSR2`. Given that, I thought it might be better to find a dedicated place to explain all the feature bits in detail.

2. The next steps would involve adding more explanations of other feature bits to this section gradually. If you think it's a good idea, I can create a post on the flashrom mailing list or bug tracker to initiate a broader discussion on this.

3. One alternative I considered is to add the notes directly to `include/flash.h`, as the original documentation mentions that available options can be found there. However, this might make the file excessively long.

4. Going back to point 2, my ultimate goal is to explain "all" the feature bits. I believe a separate section would provide better clarity than placing this information under the write-protection section. What are your thoughts?