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drivers/flash: protection API clarification

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On some targets hardware (or middelware) doesn't allow
implement functionality flash protection API -
so fare it have to be emulated by software on such a target.

This patch changes documentation of this API, so on such a targets
API might implements no-operation.

fixes #15729

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
This commit is contained in:
Andrzej Puzdrowski 2019-07-12 09:12:13 +02:00 • committed by Anas Nashif
commit aa0d41f7ec
1 changed files with 22 additions and 5 deletions
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27
include/drivers/flash.h
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@ -165,12 +165,29 @@ static inline int z_impl_flash_erase(struct device *dev, off_t offset,
* @brief Enable or disable write protection for a flash memory
*
* This API is required to be called before the invocation of write or erase
* API. Please note that on some flash components, the write protection is
* API. Any calls to flash_write() or flash_erase() that do not first disable
* write protection using this function result in undefined behavior.
* Usage Example:
* @code
* flash_write_protection_set(flash_dev, false);
* flash_erase(flash_dev, page_offset, page_size);
*
* flash_write_protection_set(flash_dev, false);
* flash_write(flash_dev, offset, data, sizeof(data));
*
* flash_write_protection_set(flash_dev, true); // enable is recommended
* @endcode
*
* Please note that on some flash components, the write protection is
* automatically turned on again by the device after the completion of each
* write or erase calls. Therefore, on those flash parts, write protection needs
* to be disabled before each invocation of the write or erase API. Please refer
* to the sub-driver API or the data sheet of the flash component to get details
* on the write protection behavior.
* call to flash_write or flash_erase(). Therefore, portable programs must
* disable write protection using this function before each call to
* flash_erase() or flash_write().
*
* For some flash devices, this function may implement a no-operation, as some
* flash hardware does not support write protection, or may not support it in
* a manner that is compatible with this API. For these drivers, this function
* always returns success.
*
* @param dev : flash device
* @param enable : enable or disable flash write protection