Some SoCs (for example Amlogic GXBB) implement a reset controller which
only supports a reset pulse (triggered via reset_control_reset). At the
same time multiple devices (in case of the Amlogic GXBB SoC both USB
PHYs) are sharing the same reset line.

This patch allows using reset_control_reset also for shared resets.
There are limitations though:
reset_control_reset can only be used if reset_control_assert was not
used yet.
reset_control_assert can only be used if reset_control_reset was not
used yet.
For shared resets the reset is only triggered once for the lifetime of
the reset_control instance (the reset can be triggered again if all
consumers of that specific reset_control are gone, as the reset
framework will free the reset_control instance in that case).
Signed-off-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Instead of potentially crashing, dump a backtrace and return -EINVAL if
rstc is NULL or an error code.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Add a device managed API for reset_controller_register().

This helps in reducing code in .remove callbacks and sometimes
dropping .remove callbacks entirely.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NLaxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

In some SoCs some hw-blocks share a reset control. Add support for this
setup by adding new:

reset_control_get_shared()
devm_reset_control_get_shared()
devm_reset_control_get_shared_by_index()

methods to get a reset_control. Note that this patch omits adding of_
variants, if these are needed later they can be easily added.

This patch also changes the behavior of the existing exclusive
reset_control_get() variants, if these are now called more then once
for the same reset_control they will return -EBUSY. To catch existing
drivers triggering this error (there should not be any) a WARN_ON(1)
is added in this path.

When a reset_control is shared, the behavior of reset_control_assert /
deassert is changed, for shared reset_controls these will work like the
clock-enable/disable and regulator-on/off functions. They will keep a
deassert_count, and only (re-)assert the reset after reset_control_assert
has been called as many times as reset_control_deassert was called.

Calling reset_control_assert without first calling reset_control_deassert
is not allowed on a shared reset control. Calling reset_control_reset is
also not allowed on a shared reset control.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Now that struct reset_control no longer stores the device pointer for
the device calling reset_control_get we can share a single struct
reset_control when multiple calls to reset_control_get are made for
the same reset line (same id / index).

This is a preparation patch for adding support for shared reset lines.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

With both the regular, _by_index and _optional variants we already have
quite a few variants of [of_]reset_control_get[_foo], the upcoming
addition of shared reset lines support makes this worse.

This commit changes all the variants into wrappers around common core
functions. For completeness sake this commit also adds a new
devm_get_reset_control_by_index wrapper.
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

The core currently doesn't check that the DT cell size matches what the
driver declares, which means that every xlate function needs to duplicate
that check.

Make sure that of_reset_control_get checks for this to avoid duplication
and errors.
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

There is no need to initialize rstc, as it is unconditionally
assigned the return value of a kzalloc call before use.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Commit 0c5b2b91 ("reset: Mark function as static and remove unused
function in core.c") removed the only user of the device pointer in
struct reset_control. As it is now unused, remove it.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

ENOSYS is reserved to report invalid syscalls to userspace.
Consistently return ENOTSUPP to indicate that the driver doesn't support
the functionality or the reset framework is not enabled at all.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

When of_reset_control_get() is called without connection ID it returns
-ENOENT when the 'resets' property doesn't exists or is an empty entry.
However when a connection ID is given it returns -EINVAL when the 'resets'
property doesn't exists or the requested name can't be found. This is
because the error code returned by of_property_match_string() is just
passed down as an index to of_parse_phandle_with_args(), which then
returns -EINVAL.

To get a consistent return value with both code paths we must return
-ENOENT when of_property_match_string() fails.
Signed-off-by: NAlban Bedel <albeu@free.fr>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Add of_reset_control_get_by_index() to allow the drivers to get reset
device without knowing its name.
Signed-off-by: NVince Hsu <vinceh@nvidia.com>
[jonathanh@nvidia.com: Updated stub function to return -ENOTSUPP instead
 of -ENOSYS which should only be used for system calls.]
Signed-off-by: NJon Hunter <jonathanh@nvidia.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

There are cases where a system will want to read a reset status bit before
doing any other toggling. Add a reset_control_status helper function to the
reset controller API.
Signed-off-by: NDinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

In some cases, you might need to deassert from reset an hardware block that
doesn't associated to a struct device (CPUs, timers, etc.).

Add a small helper to retrieve the reset controller from the device tree
without the need to pass a struct device.
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

Mark function of_reset_simple_xlate() as static in core.c
because it is not used outside this file.
Also, remove functions devm_reset_control_put() and
devm_reset_control_match() because they are unused.

This eliminates the following warnings in core.c:
drivers/reset/core.c:46:5: warning: no previous prototype for ‘of_reset_simple_xlate’ [-Wmissing-prototypes]
drivers/reset/core.c:262:6: warning: no previous prototype for ‘devm_reset_control_put’ [-Wmissing-prototypes]
Signed-off-by: NRashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

If the requested reset controller is not yet available, have reset_control_get
and device_reset return -EPROBE_DEFER so the driver can decide to request
probe deferral.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Reviewed-by: NStephen Warren <swarren@nvidia.com>

"rstc" is NULL here and we should use "rcdev" instead of "rstc->rcdev".
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

This adds a simple API for devices to request being reset
by separate reset controller hardware and implements the
reset signal device tree binding.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NStephen Warren <swarren@nvidia.com>
Reviewed-by: NShawn Guo <shawn.guo@linaro.org>
Reviewed-by: NMarek Vasut <marex@denx.de>
Reviewed-by: NPavel Machek <pavel@ucw.cz>