Fix a user API regression introduced with commit f76edd8f7ce0 ("tty: cyclades, remove this orphan"), which removed a part of the API and caused compilation errors for user programs using said part, such as GCC 9 in its libsanitizer component[1]:

.../libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc:160:10: fatal error: linux/cyclades.h: No such file or directory 160 | #include <linux/cyclades.h> | ^~~~~~~~~~~~~~~~~~ compilation terminated. make[4]: *** [Makefile:664: sanitizer_platform_limits_posix.lo] Error 1

As the absolute minimum required bring `struct cyclades_monitor' and ioctl numbers back then so as to make the library build again. Add a preprocessor warning as to the obsolescence of the features provided.

References:

[1] GCC PR sanitizer/100379, "cyclades.h is removed from linux kernel header files", https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100379

Signed-off-by: Maciej W. Rozycki macro@embecosm.com Fixes: f76edd8f7ce0 ("tty: cyclades, remove this orphan") Cc: stable@vger.kernel.org # v5.13+ --- Changes from v2:

- Add #warning directives.

Changes from v1:

- Adjust heading from "tty: Revert the removal of the Cyclades public API".

- Only revert `struct cyclades_monitor' and ioctl numbers.

- Properly format the change given that it's not a plain revert anymore. --- include/uapi/linux/cyclades.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)

linux-uapi-cyclades.diff Index: linux/include/uapi/linux/cyclades.h =================================================================== --- /dev/null +++ linux/include/uapi/linux/cyclades.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ + +#ifndef _UAPI_LINUX_CYCLADES_H +#define _UAPI_LINUX_CYCLADES_H + +#warning "Support for features provided by this header has been removed" +#warning "Please consider updating your code" + +struct cyclades_monitor { + unsigned long int_count; + unsigned long char_count; + unsigned long char_max; + unsigned long char_last; +}; + +#define CYGETMON 0x435901 +#define CYGETTHRESH 0x435902 +#define CYSETTHRESH 0x435903 +#define CYGETDEFTHRESH 0x435904 +#define CYSETDEFTHRESH 0x435905 +#define CYGETTIMEOUT 0x435906 +#define CYSETTIMEOUT 0x435907 +#define CYGETDEFTIMEOUT 0x435908 +#define CYSETDEFTIMEOUT 0x435909 +#define CYSETRFLOW 0x43590a +#define CYGETRFLOW 0x43590b +#define CYSETRTSDTR_INV 0x43590c +#define CYGETRTSDTR_INV 0x43590d +#define CYZSETPOLLCYCLE 0x43590e +#define CYZGETPOLLCYCLE 0x43590f +#define CYGETCD1400VER 0x435910 +#define CYSETWAIT 0x435912 +#define CYGETWAIT 0x435913 + +#endif /* _UAPI_LINUX_CYCLADES_H */