On a QSFPTEK QT-SFP+-T (RTL8261C) 10GBase-T module, the diag type field
(92) comes back as 0x00, but there's actually some statistics available
like temperature. Other metrics may be hard-coded values.
Add a basic struct that allows matching on vendor and/or model, using a
bitfield to allow multiple quirks for a given SFP module. Only
SFP_QUIRK_DDM is implemented.
For modules matching SFP_QUIRK_DDM, attempt an I2C read of the MSB of
module voltage during probe if DDM is "unsupported" - if it's not 0xff,
override the reported options so we can pull the diagnostic data.
To allow simpler comparisons, convert the ASCII fields (vendor,
model, serial) from space-padded to standard NULL-terminated strings.
strcmp() is moved from httpd.c to rtlplayground.c alongside other string
functions and shared between them.
The __reentrant keyword is used for the new functions to avoid using up
additional OSEG space. This allocates the variables on the stack, which
is OK for this particular code path.
The JSON assembly in send_status() is slightly modified to treat the
sfp_module_* data as standard NULL-terminated strings, and a repeated
subtraction was moved into a uint8_t to declutter the code.
A commonly used SFP+ form-factor XGS-PON ONT (WAS-110) reports 0x63 at
power on and then switches to 0x64 after booting up.
0x63 -> 9.9gbps
0x64 -> 10gbps
These are outside of the previous 0x66-0x69 range which prevented the
link from ever being brought up.
Matt Merhar