mtd: spi-nor: add a stateless method to support memory size above 128Mib

Hi all,

this series of patches is based on the git://github.com/spi-nor/linux.git
tree. It has been extracted from the SFDP series and is resent as a standalone series.

This series fixes compatibility issue between Linux and many bootloaders when using SPI flash with size greater than 128Mib.

Indeed, before this series, Linux used to make the SPI flash memory enter its 4-byte address mode when its size is greater than 128Mib: The very same Fast Read 1-1-z op code is used, for instance Fast Read 1-1-4 (6Bh) but once in 4-byte address mode, the SPI flash memory now expects a 4-byte address following the op code instead of a 3-byte address. This solution is statefull: it changes the internal state of the memory.

Hence, when the CPU is reset but not the memory, many bootloaders are not aware of this internal state change at the memory side, don't know how to handle this and still send one Fast Read op code followed by a 3-byte address. So the bootloader fails to read data from the SPI flash memory.

ChangeLog:

v3 -> v4:
- replace "++i" by "i++" in a "for" loop.
- add a new "size" parameter to spi_nor_convert_opcode() and use the ARRAY_SIZE() macro instead of a null sentinel at the end the table array.

v2 -> v3:
- no change on patch 1.
- rebase patch 2 on the spi-nor tree: SPI_NOR_4B_OPCODES is changed from BIT(10) to BIT(11), otherwise patch could be applied on linux-next.
- remove helper macro such as ENTRY_3TO4()
- split the 3to4 opcode table into 3 different tables for read, program and erase op codes.

v1 -> v2:
- collect Acked-by for patch 1.
- replace the dichotomic search by a simple for() loop for better clarity purpose in patch 2.

Cyrille Pitchen (2):
mtd: spi-nor: rename SPINOR_OP_* macros of the 4-byte address op codes
mtd: spi-nor: add a stateless method to support memory size above

    128Mib

 drivers/mtd/devices/serial_flash_cmds.h |   7 ---
 drivers/mtd/devices/st_spi_fsm.c        |  28 ++++-----
 drivers/mtd/spi-nor/spi-nor.c           | 101 +++++++++++++++++++++++++-------
 drivers/spi/spi-bcm-qspi.c              |   6 +-
 include/linux/mtd/spi-nor.h             |  22 +++++--
 5 files changed, 113 insertions(+), 51 deletions(-)

2.7.4