[0/3] TI QSPI: Add support for large flash devices

Message

Jean Pihet Dec. 6, 2019, 4 p.m. UTC

Large devices are bigger than >64MB in size.

- Fix the SPI clock generation in order to produce the desired
  frequency.
- Since the TI QSPI IP block only maps 64MB of MMIO, use MMIO
  below the 64MB boundary and software generated transfers above.
- Optimize the software generated transfers for dual and quad
  I/O read operations. The speed-up is 3.5x for quad I/O reads.

Tested using raw accesses (mtd_debug) and JFFS2 FS read/write/erase;
in single, dual and quad modes.
All accesses have been checked on the logic analyzer.

Jean Pihet (3):
  TI QSPI: Fix fclk frequency
  TI QSPI: support large flash devices
  TI QSPI: optimize transfers for dual and quad read

 drivers/spi/spi-ti-qspi.c | 83 +++++++++++++++++++++++++++++----------
 1 file changed, 63 insertions(+), 20 deletions(-)