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⚠️ [XIP] reworked execute in place module #249

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merged 7 commits into from
Jan 6, 2022
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@stnolting stnolting commented Jan 6, 2022

This PR is a rework of the processor's Execute in Place (XIP) module (#244).

  • Control register changes
    • removed QSPI mode enable (not implemented yet 😉)
    • rearranged flags
    • removed XIP mode busy flag
    • added flag to explicitly enable the module's SPI chip-select port (allows to send dummy clocks without actually enabling the SPI flash)

Further hardware changes:

  • removed hardware-based sending of dummy SPI clocks (is now done by the XIP's software library functions)
  • removed "inter-transmission" pause from SPI PHY - faster SPI accesses
  • reduces hardware footprint: only ~300 LEs on an Intel Cyclone IV

⚙️ "Final" pre-defined software functions for using the XIP module:

int neorv32_xip_available(void);
int neorv32_xip_init(uint8_t prsc, uint8_t cpol, uint8_t cpha, uint8_t rd_cmd);
int neorv32_xip_start(uint8_t abytes, uint32_t page_base);
int neorv32_xip_spi_trans(uint8_t nbytes, uint64_t *rtx_data);

💡 A demo program using the XIP module is available in sw/example/demo_xip/main.c.

@stnolting stnolting added enhancement New feature or request HW Hardware-related labels Jan 6, 2022
@stnolting stnolting self-assigned this Jan 6, 2022
@stnolting stnolting marked this pull request as ready for review January 6, 2022 15:57
@stnolting stnolting merged commit 0df34dc into master Jan 6, 2022
@stnolting stnolting deleted the rework_xip branch January 6, 2022 19:53
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