ot_flash: Allow reads of initialized PHY flash with an uninitialized flash_ctrl
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This was referenced Nov 11, 2025
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From further testing this appears to actually be the case for all the flash operations, not just reading. I've tried looking through the RTL and can't see any links that would disable flash PHY programming/erasing when the flash protocol controller is not initialized, and tests seem to rely on being able to program without initializing in some cases. Updated to use this (simpler) behaviour now. |
jwnrt
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Nov 12, 2025
Turns out the flash controller initialization is even more of a special case then thought. The physical flash macro needs to be initialized, but this is vendor-specific and not useful to emulate so we always just say the flash PHY is initialized. The HW should specifically allow operations on uninitialized flash, but reads specifically are handled somewhat differently. This is explained in more detail in the comment in this commit. Signed-off-by: Alex Jones <alex.jones@lowrisc.org>
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See the comment in the commit. It turns out that initialization is even more of a special-case than previously realized in the flash controller.
This is needed to get some SRAM execution flows working (which read from flash with the flash_ctrl uninitialized, see
sram_start.Sandast_program.cin OpenTitan). Examples are e.g. the//sw/device/tests:rv_core_ibex_isa_test_{}or//sw/device/tests:rv_core_ibex_epmp_test_{}in upstream OpenTitan.