Currently, we must call cyclic_init() at some point before
cyclic_register() becomes possible. That turns out to be somewhat
awkward, especially with SPL, and has resulted in a watchdog callback
not being registered, thus causing the board to prematurely reset.
We already rely on gd->cyclic reliably being set to NULL by the asm
code that clears all of gd. Now that the cyclic list is a hlist, and
thus an empty list is represented by a NULL head pointer, and struct
cyclic_drv has no other members, we can just as well drop a level of
indirection and put the hlist_head directly in struct
global_data. This doesn't increase the size of struct global_data,
gets rid of an early malloc(), and generates slightly smaller code.
But primarily, this avoids having to call cyclic_init() early; the cyclic
infrastructure is simply ready to register callbacks as soon as we
enter C code.
We can still end up with schedule() being called from asm very early,
so we still need to check that gd itself has been properly initialized
[*], but once it has, gd->cyclic_list is perfectly fine to access, and
will just be an empty list.
As for cyclic_uninit(), it was never really the opposite of
cyclic_init() since it didn't free the struct cyclic_drv nor set
gd->cyclic to NULL. Rename it to cyclic_unregister_all() and use that
in test/, and also insert a call at the end of the board_init_f
sequence so that gd->cyclic_list is a fresh empty list before we enter
board_init_r().
A small piece of ugliness is that I had to add a cast in
cyclic_get_list() to silence a "discards 'volatile' qualifier"
warning, but that is completely equivalent to the existing handling of
the uclass_root_s list_head member.
[*] I'm not really sure where we guarantee that the register used for
gd contains 0 until it gets explicitly initialized, but that must be
the case, otherwise testing gd for being NULL would not make much sense.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mm-venice-*
A hlist is headed by just a single pointer, so can only be traversed
forwards, and insertions can only happen at the head (or before/after
an existing list member). But each list node still consists of two
pointers, so arbitrary elements can still be removed in O(1).
This is precisely what we need for the cyclic_list - we never need to
traverse it backwards, and the order the callbacks appear in the list
should really not matter.
One advantage, and the main reason for doing this switch, is that an
empty list is represented by a NULL head pointer, so unlike a
list_head, it does not need separate C code to initialize - a
memset(,0,) of the containing structure is sufficient.
This is mostly mechanical:
- The iterators are updated with an h prefix, and the type of the
temporary variable changed to struct hlist_node*.
- Adding/removing is now just hlist_add_head (and not tail) and
hlist_del().
- struct members and function return values updated.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mm-venice-*
We're already relying on gd->cyclic being NULL before cyclic_init() is
called - i.e., we're relying on all of gd being zeroed before entering
any C code. And when we do populate gd->cyclic, its ->cyclic_ready
member is automatically set to true. So we can actually just rely on
testing gd->cyclic itself.
The only wrinkle is that cyclic_uninit() actually did set
->cyclic_ready to false. However, since it doesn't free gd->cyclic,
the cyclic infrastructure is actually still ready (i.e., the list_head
is properly initialized as an empty list).
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mm-venice-*
As a preparation for future patches, use a flag in gd->flags rather
than a separate member in (the singleton) struct cyclic_drv to keep
track of whether we're already inside cyclic_run().
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mm-venice-*
With the migration of the watchdog infrastructure to cyclic functions
it's been noticed, that at least one watchdog driver is broken now. As
the execution time of it's watchdog reset function is quite long.
In general it's not really necessary (right now) to disable the cyclic
function upon exceeding CPU time usage. So instead of disabling the
cylic function in this case, let's just print a warning once to show
this potential problem to the user.
Signed-off-by: Stefan Roese <sr@denx.de>
Suggested-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Tom Rini <trini@konsulko.com>
Cc: Pali Rohár <pali@kernel.org>
This patch introduces a schedule() function, which shall be used instead
of the old WATCHDOG_RESET. Follow-up patches will make sure, that this
new function is used.
Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Tom Rini <trini@konsulko.com> [am335x_evm, mx6cuboxi, rpi_3,dra7xx_evm, pine64_plus, am65x_evm, j721e_evm]
Add the basic infrastructure to periodically execute code, e.g. all
100ms. Examples for such functions might be LED blinking etc. The
functions that are hooked into this cyclic list should be small timewise
as otherwise the execution of the other code that relies on a high
frequent polling (e.g. UART rx char ready check) might be delayed too
much. This patch also adds the Kconfig option
CONFIG_CYCLIC_MAX_CPU_TIME_US, which configures the max allowed time
for such a cyclic function. If it's execution time exceeds this time,
this cyclic function will get removed from the cyclic list.
How is this cyclic functionality executed?
The following patch integrates the main function responsible for
calling all registered cyclic functions cyclic_run() into the
common WATCHDOG_RESET macro. This guarantees that cyclic_run() is
executed very often, which is necessary for the cyclic functions to
get scheduled and executed at their configured periods.
This cyclic infrastructure will be used by a board specific function on
the NIC23 MIPS Octeon board, which needs to check periodically, if a
PCIe FLR has occurred.
Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
