drivers: flash: Add support for Atmel AT25 SPI flash variant

[Liam-Ogletree]

The AT25XV021A variant is a flash variant of Atmel's AT25 family that adds extra protections, requiring additional writes to the device to program or erase data.

This commit adds a flash driver for AT25XV021A devices instead of modifying (1) the existing AT45 SPI flash driver or (2) the existing AT24/25 EEPROM driver because this variant poses fundamental changes that affect all aspects of the driver.

Notably,

• AT25XV021A includes a second status register, and the format and functions of the existing status register is changed from the existing drivers.
• AT25XV021A requires executing page or chip erase commands before writing, making it incompatible with the existing AT24/25 EEPROM driver.
• AT25XV021A adds a software protection layer that requires extra writes before executing program or erase commands.

Tested writing to and erasing from an AT25XV021A device. Tested reading from an AT25XV021A device across page boundaries. Tested chip erase function. Tested driver initialization from varying initial hardware states.

[github-actions]

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[rriveramcrus]

It would be good to add an entry to tests/drivers/build_all/flash/spi.dtsi

[Liam-Ogletree]

It would be good to add an entry to tests/drivers/build_all/flash/spi.dtsi

Added an entry to /spi.dtsi for this flash driver.

[pdgendt]

Thanks!

[Liam-Ogletree]

Thanks!

Erroneous _ in spi.dtsi, updated from page_size to page-size as a result of failed twister test (one of 8)

[de-nordic]

Write should not do erase.
Write should not potentially destroy existing data.
Write block size is not 1 and it is not clearly visible, from user perspective, that selected wbs reduces significantly endurance of a device from the one stated in datasheet.

[Liam-Ogletree]

Write should not do erase. Write should not potentially destroy existing data. Write block size is not 1 and it is not clearly visible, from user perspective, that selected wbs reduces significantly endurance of a device from the one stated in datasheet.

Hi @de-nordic

Thank you for the review! I updated both erase and write to no longer implicitly write and erase, respectively, and added checks for page size alignment where appropriate. Additionally, I added a compile-time check for read-only and hid most functions and some config variables behind #if !(DEV_READ_ONLY) macros to reduce code size in case of read only. Finally, updated write_block_size to equal DEV_PAGE_SIZE.

Appreciate your time!
Liam

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
5.1% Duplication on New Code

See analysis details on SonarQube Cloud