We need to protect access to the param_values array. This is dynamically
allocated and resized (utarray_reserve() calls realloc). If some thread
was iterating the array while another was resizing the array, the first one
would iterate on a freed array, thus accessing invalid memory.

On NuttX this could lead to hardfaults in rare conditions.

Unfortunately we need to initialize the semaphore on startup, by calling
sem_init(). This adds a param_init() method called by every board/config
that uses the params (at least I think I've found all of them)

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

This brings in many of the changes from the PX4 fork on ATLFLight.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

This brings in many of the changes from the PX4 fork on ATLFLight.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

When px4_getpid() was called from the shell, there was no opaque
thread ID to return. Added a special thread ID for the shell
context. This ID only works for px4_getpid() and cannot be used
for other px4_task_*() calls.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

The header file now contains all hrt workqueue related prototypes.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

There is a race condition for the accel and mag polling rates.
Whichever one gets set first, the other will be uninitialized.

Set the mag polling rate to 1ms if uninitilized.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

The HRT call processing normally happens via HW timer interrupt
handler. Since the POSIX port has no ISR handling, the HP work
queue is used.

Instead of irq_save() and irq_restore() calls to disable/enable
interrupts, a mutex is used to protect each queue.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

In STM32, the ISR handler calls hrt_call_invoke(). There is no
interrupt timer inthe POSIX port so a work item is put on the
high priority work queue to expire at the next event (in ticks)
or at the next max delay interval.

Counter wrapping is likely still not handled properly in this code.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Changed "linux" target to "posix". Most of the changes are shared with
QuRT and with OSX. The Linux specific parts are in for i2c which uses
<linux/i2c.h> and <linux/i2c-dev.h>.

There is also a check for __PX4_LINUX in mavlink for a tty ioctl that is
not supported.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Disabled gcc warnings that are tripped by Eigen.

Removed signal code that is not needed in Linux port and was
causing gcc warnings.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

PX4 uses NuttX data structures throughout so those data structures
were preserved and used to implement high and low priority queues.

A unit test for the work queues was added.

The polling rate of the queues are set in px4_config.h in
CONFIG_SCHED_WORKPERIOD. The units are milliseconds.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Based on NuttX work queue code.

Not yet functional.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Added more queue support to linux/px4_layer.

Use virt char devices for ms5611, and mavlink.

Added more HRT functionality. uORB latency test
now fails. Likely due to bad HRT impl for Linux.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

uORB module now compiles and runs for Linux using the
virtual CDev implementation.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Fixes to compile with gcc

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Uncomment the following line in setup.mk and comment out the line above
to enable the Linux build.

   export PX4_TARGET_OS	 = linux

The build uses the clang compiler by default. The final bundled executable
is mainapp located in:

   Build/linux_default.build/mainapp

When you run mainapp it will provide a list of the built-in apps. You can
type in the commands to run such as:

   hello_main start

Because the Linux build is threaded and does not support tasks or processes,
it cannot call errx, exit() _exit(), etc. It also requires unique scoped
variables to test if a thread is running or if an application should exit.
The px4::AppMgr class was added in px4_app.h for this purpose. The
hello sample app demonstrates how this is used.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>