spiFlashdb: add MX25R6435F and fix SPIFlash::bp_to_len

[pu-cc]

This device was missing in spiFlashdb and is installed on the GateMate evaluation board.

MX25R6435F's status register contains a quad-enable bit.

If it is set, SPIFlash::bp_to_len incorrectly masks all sectors, even if no bp-bit is set. This fix seems obvious to me, but I don't have many boards to test this.

[trabucayre]

bp_len is 4 but you only provides 3 positions. Maybe the issue is related to that. I will investigate too.

[trabucayre]

it's true! Its wrong to substract something to 0!

[trabucayre]

Applied. Thanks @pu-cc.

I have to check too but maybe the issue is related to the quad mode with a bad read and an flash's answer containing 0xff ?

[pu-cc]

Thank you, @trabucayre!

I does not seem that the status register is misread. 0x40 is QE bit:

write to flash
Jtag frequency : requested 10.00MHz  -> real 10.00MHz 
found 1 devices
index 0:
        idcode 0x20000001
        manufacturer colognechip
        family GateMate Series
        model  GM1Ax
        irlength 6
File type : cfg
c2 28 17 c2 read c22817c2
Detected: Macronix MX25R6435F 128 sectors size: 64Mb
RDSR : 40  <- here
WIP  : 0
WEL  : 0
BP   : 0
TB   : 0
SRWD : 0
00000000 00000000 00000000 40

We just did not return from SPIFlash::bp_to_len if bp != 0, and later subtract to 0:

openFPGALoader/src/spiFlash.cpp

Line 890 in 1d276eb

if (bp == 0)

The fix mentioned in #447 (comment) solves the issues and with the current status everything is perfect for me. Thanks again!