it seems it was a typo.

TIOCM_ macros were wrongly using the asm-generic/termios.h definitions
instead of the mips specific ones from asm/termios.h

mips and powerpc use their own asm/ioctls.h, not the asm-generic/ioctls.h
and they lack termiox macros that are available on other targets.
see kernel commit 1d65b4a088de407e99714fdc27862449db04fb5c

these are defined in linux asm/ioctls.h.
(powerpc64 and powerpc bits/ioctl.h are now identical)

glibc ioctl.h has it too.

TIOCTTYGSTRUCT, TIOCGHAYESESP, TIOCSHAYESESP and TIOCM_MODEM_BITS
were removed from the linux uapi and not present in glibc ioctl.h

based on patch submitted by Jaydeep Patil, with minor changes.

patch by Mahesh Bodapati and Jaydeep Patil of Imagination
Technologies.

untested; hopefully it's right now

basically, this version of the code was obtained by starting with
rdp's work from his ellcc source tree, adapting it to musl's build
system and coding style, auditing the bits headers for discrepencies
with kernel definitions or glibc/LSB ABI or large file issues, fixing
up incompatibility with the old binutils from aboriginal linux, and
adding some new special cases to deal with the oddities of sigaction
and pipe syscall interfaces on mips.

at present, minimal test programs work, but some interfaces are broken
or missing. threaded programs probably will not link.

based on patch by nik