asm/termios.h has tons of duplication and rather
convoluted logics re includes.
First of all, while everyone has uapi asm/termios.h,
some architectures have asm/termios.h and some do not. So
include of <asm/termios.h> can go either to arch asm/termios.h,
or to uapi/asm/termios.h.
In the former case asm/termios.h defines a bunch of
helpers (used in just one file) and a constant (3 more users)
and includes uapi/asm/termios.h
In the latter... uapi/asm/termios.h is in generated-y
or equivalent to it. Which is to say, it ends up doing
#include <asm-generic/termios.h>. Userland-side that would
refer to uapi/asm-generic/termios.h, but kernel-side we end
up with plain asm-generic/termios.h. Which defines the same
set of helpers and a constant and pulls uapi/asm-generic/termios.h
Helpers in question are heavily shared; there is an attempt
to put them into a common header (termios-base.h), but not all
instances use it. Another unpleasant thing is that said helpers
tend to be macros, with very little typechecking. And all of that
is pulled in by a lot more places than those that are actually
interested - 500-odd instead of 4.
Below is an attempt to untangle that; the branch is vfs.git#work.termios,
patches in followups. FWIW, diffstat is
arch/Kconfig | 3 +
arch/alpha/Kconfig | 1 +
arch/alpha/include/asm/termios.h | 81 ------------
arch/alpha/include/asm/termios_internal.h | 72 ++++++++++
arch/ia64/include/asm/termios.h | 58 --------
arch/mips/include/asm/termios.h | 105 ---------------
arch/parisc/include/asm/termios.h | 52 --------
arch/powerpc/Kconfig | 1 +
.../include/asm/{termios.h => termios_internal.h} | 7 +-
arch/riscv/include/asm/Kbuild | 1 -
arch/s390/include/asm/termios.h | 26 ----
arch/sparc/Kconfig | 1 +
arch/sparc/include/asm/termios.h | 147 ---------------------
arch/sparc/include/asm/termios_internal.h | 134 +++++++++++++++++++
arch/x86/include/uapi/asm/Kbuild | 1 +
arch/x86/include/uapi/asm/termios.h | 1 -
drivers/tty/hvc/hvcs.c | 1 +
drivers/tty/n_hdlc.c | 1 -
drivers/tty/tty_io.c | 1 +
drivers/tty/tty_ioctl.c | 1 +
drivers/tty/vcc.c | 1 +
include/asm-generic/termios-base.h | 78 -----------
include/asm-generic/termios.h | 108 ---------------
include/linux/termios_internal.h | 137 +++++++++++++++++++
24 files changed, 355 insertions(+), 664 deletions(-)
delete mode 100644 arch/alpha/include/asm/termios.h
create mode 100644 arch/alpha/include/asm/termios_internal.h
delete mode 100644 arch/ia64/include/asm/termios.h
delete mode 100644 arch/mips/include/asm/termios.h
delete mode 100644 arch/parisc/include/asm/termios.h
rename arch/powerpc/include/asm/{termios.h => termios_internal.h} (70%)
delete mode 100644 arch/s390/include/asm/termios.h
delete mode 100644 arch/sparc/include/asm/termios.h
create mode 100644 arch/sparc/include/asm/termios_internal.h
delete mode 100644 arch/x86/include/uapi/asm/termios.h
delete mode 100644 include/asm-generic/termios-base.h
delete mode 100644 include/asm-generic/termios.h
create mode 100644 include/linux/termios_internal.h
