Master

* stm32_hrtim.c: fix burst mode prescaler update

* powerled.h: add fault field to state structure

* stm32f334-disco: add flash mode support for powerled driver + cosmetics

Approved-by: Gregory Nutt <gnutt@nuttx.org>

 libc and libnx:  When the libraries are built into two libraries, a user space library and a OS space library (as in the PROTECTED and KERNEL build).  Then the user space library must not use the OS internal interfaces; similarly, the OS must avoid using the userspace interfaces so that it does not muck the errno value or create spurious cancellation points.

libc and libnx:  When the libraries are built into two libraries, a user space library and a OS space library (as in the PROTECTED and KERNEL build).  Then the user space library must not use the OS internal interfaces; similarly, the OS must avoid using the userspace interfaces so that it does not muck the errno value or create spurious cancellation points.

configs/z80sim: Fix a naming problem.  Also, don't try to build the serial driver if CONFIG_NFILE_DESCRIPTOR=0.

libc/stdio:  Build the lib_noflush() and lib_snoflush() stubs even if CONFIG_FILE_DESCRIPTORS=0.  They may still be needed.

Fix some problems in the previous commits:  Forgot to update sigset() after change to prototype.  Also there was a stray semicolon in the change signal().

SDCC Fixes:  Change some prototypes and some assumptions about the size of unsigned int to get to a clean SDCC compile.

Fix some build problems after recent separation of internal OS from application interfaces.  The build problem only occurs in the PROTECTED and KERNEL builds where separate libraries are built for the applications and for use within the OS. In these cases, the correct interfaces must be used.  This commit fixes a few of these, so I can get through build testing, but there are many more that need fixin'.

sama5d4-ek:  Remove a really old defconfig example file that is so far out of date that it can only be misleading.

    Replace all calls to sigprocmask() in the OS proper with calls to nxsig_procmask().

    sched/signal:  Add internal OS interface nxsig_procmask().  This internal interface is equivalent to the standard sigprocmask() used by applications except that it does not modify the errno value.  Also fixes a problem in that the original sigprocmask() was not setting the errno.

    Replace all calls to sigqueue() in the OS proper with calls to nxsig_queue() to avoid accessing the errno variable.

    sched/signal:  Add nxsig_queue() which is functionally equivalent to sigqueue() except that it does not modify the errno variable.

    Replace all usage kill() in the OS proper with nxsig_kill().

    sched/signal:  Add nxsig_kill() which is functionally equivalent to kill() except that it does not modify the errno variable.

mm/: Heap semaphore logic needs to use nxsem_* interfaces when available, but the standard semaphores only when implementing a user-space heap.  Not this does introduce and issue:  the memory management functions them become cancellation points because of the use of sem_wait.

drivers/serial/tcdrain:  tcdrain() was recently added to the NuttX C library.  But there is a problem.  The specification of tcdrain() requires that it be a cancellation point.  In order to do this, tcdrain was moved from the C library into the OS and the addition cancellation point hooks were added.  In non-FLAT builds, access via system calls is also now supported.

Adds new OS internal functions nxsig_sleep() and nxsig_usleep.  These differ from the standard sleep() and usleep() in that (1) they don't cause cancellation points, and (2) don't set the errno variable (if applicable).  All calls to sleep() and usleep() changed to calls to nxsig_sleep() and nxsig_usleep().

Squashed commit of the following:

    Change all calls to usleep() in the OS proper to calls to nxsig_usleep()

    sched/signal:  Add a new OS internal function nxsig_usleep() that is functionally equivalent to usleep() but does not cause a cancellaption point and does not modify the errno variable.

    sched/signal:  Add a new OS internal function nxsig_sleep() that is functionally equivalent to sleep() but does not cause a cancellaption point.

  sigtimedwait() -> nxsig_timedwait()
  sigwaitinfo()  -> nxsig_waitinfo()
  nanosleep()    -> nxsig_nanosleep()

The internal OS versions differ from the standard application interfaces in that:

  - They do not create cancellation points, and
  - they do not modify the application's errno variable

Squashed commit of the following:

    sched/signal:  Replace all usage of sigwaitinfo(), sigtimedwait(), and nanosleep() with the OS internal counterparts nxsig_waitinfo(), nxsig_timedwait(), and nxsig_nanosleep().

    sched/signal:  Add nxsig_nanosleep().  This is an internal OS version of nanosleep().  It differs in that it does not set the errno varaiable and does not create a cancellation point.

    sched/signal:  Add nxsig_timedwait() and nxsig_waitinfo().  These are internal OS versions of sigtimedwait() and sigwaitinfo().  They differ in that they do not set the errno varaiable and they do not create cancellation points.

fs/vfs and net/socket:  fcntl() is not return success fail for F_SETFL.  Reported by Jussi Kivilinna.

What was I thinking?  I missed that litle minus sign and the possibility that the errno might be some positive non-zero value.

This reverts commit 43880878.

This change renames all internal, private NuttX signal-related functions to use the prefix nxsig_ so that they cannot be confused with application interfaces that begin, primarily, with sig_

This is analogous to similar renaming that was done previously for semaphores.

Squashed commit of the following:

    sched/signal:  Fix a few compile warnings introduced by naming changes.

    sched/signal:  Rename all private, internal signl functions to use the nxsig_ prefix.

    sched/signal:  Rename sig_removependingsignal, sig_unmaskpendingsignal, and sig_mqnotempty to nxsig_remove_pendingsignal, nxsig_unmask_pendingsignal, and nxsig_mqnotempty to make it clear that these are OS internal interfaces.

    sched/signal:  Rename sig_findaction and sig_lowest to nxsig_find_action and nxsig_lowest to make it clear that these are OS internal interfaces.

    sched/signal:  Rename sig_allocatepingsigaction and sig_deliver to nxsig_alloc_pendingsigaction and nxsig_deliver to make it clear that these are OS internal interfaces.

    sched/signal:  Rename sig_cleanup, sig_release, sig_releasependingaction, and sig_releasependingsignal to nxsig_cleanup, nxsig_release, nxsig_release_pendingaction, and nxsig_release_pendingsignal to make it clear that these are OS internal interfaces.

    sched/signal:  Rename sig_tcbdispatch and sig_dispatch to nxsig_tcbdispatch and nxsig_dispatch to make it clear that these are OS internal interfaces.

    sched/signal:  Rename sig_releaseaction and sig_pendingset to nxsig_release_action and nxsig_pendingset to make it clear that these are OS internal interfaces.

    sched/signal:  Rename sig_initialize and sig_allocateactionblock to nxsig_initialize and nxsig_alloc_actionblock to make it clear that these are OS internal interfaces.

sched/semaphore:  sem_trywait() modifies the errno value and, hence, should not be used within the OS.  Use nxsem_trywait() instead.

sched/semaphore:  sem_timedwait() is a cancellation point and, hence, cannot be called from within the OS.  Created nxsem_timedwait() that is equivalent but does not modify the errno and does not cause cancellation.  All calls to sem_timedwait() change to calls to nxsem_timedwait() in the OS.

    This commit backs out most of commit b4747286.  That change was added because sem_wait() would sometimes cause cancellation points inappropriated.  But with these recent changes, nxsem_wait() is used instead and it is not a cancellation point.

    In the OS, all calls to sem_wait() changed to nxsem_wait().  nxsem_wait() does not return errors via errno so each place where nxsem_wait() is now called must not examine the errno variable.

    In all OS functions (not libraries), change sem_wait() to nxsem_wait().  This will prevent the OS from creating bogus cancellation points and from modifying the per-task errno variable.

    sched/semaphore:  Add the function nxsem_wait().  This is a new internal OS interface.  It is functionally equivalent to sem_wait() except that (1) it is not a cancellation point, and (2) it does not set the per-thread errno value on return.

    sched/semaphore:  Add nxsem_post() which is identical to sem_post() except that it never modifies the errno variable.  Changed all references to sem_post in the OS to nxsem_post().

    sched/semaphore:  Add nxsem_destroy() which is identical to sem_destroy() except that it never modifies the errno variable.  Changed all references to sem_destroy() in the OS to nxsem_destroy().

    libc/semaphore and sched/semaphore:  Add nxsem_getprotocol() and nxsem_setprotocola which are identical to sem_getprotocol() and set_setprotocol() except that they never modifies the errno variable.  Changed all references to sem_setprotocol in the OS to nxsem_setprotocol().  sem_getprotocol() was not used in the OS