reset: Instantiate reset GPIO controller for shared reset-gpios

Devices sharing a reset GPIO could use the reset framework for
coordinated handling of that shared GPIO line. We have several cases of
such needs, at least for Devicetree-based platforms.

If Devicetree-based device requests a reset line, while "resets"
Devicetree property is missing but there is a "reset-gpios" one,
instantiate a new "reset-gpio" platform device which will handle such
reset line. This allows seamless handling of such shared reset-gpios
without need of changing Devicetree binding [1].

To avoid creating multiple "reset-gpio" platform devices, store the
Devicetree "reset-gpios" GPIO specifiers used for new devices on a
linked list. Later such Devicetree GPIO specifier (phandle to GPIO
controller, GPIO number and GPIO flags) is used to check if reset
controller for given GPIO was already registered.

If two devices have conflicting "reset-gpios" property, e.g. with
different ACTIVE_xxx flags, this would allow to spawn two separate
"reset-gpio" devices, where the second would fail probing on busy GPIO
request.

Link: https://lore.kernel.org/all/YXi5CUCEi7YmNxXM@robh.at.kernel.org/ [1]
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240129115216.96479-5-krzysztof.kozlowski@linaro.org
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Fix crash when freeing non-existent optional resets

When obtaining one or more optional resets, non-existent resets are
stored as NULL pointers, and all related error and cleanup paths need to
take this into account.

Currently only reset_control_put() and reset_control_bulk_put()
get this right. All of __reset_control_bulk_get(),
of_reset_control_array_get(), and reset_control_array_put() lack the
proper checking, causing NULL pointer dereferences on failure or
release.

Fix this by moving the existing check from reset_control_bulk_put() to
__reset_control_put_internal(), so it applies to all callers.
The double check in reset_control_put() doesn't hurt.

Fixes: 17c82e206d2a3cd8 ("reset: Add APIs to manage array of resets")
Fixes: 48d71395896d54ee ("reset: Add reset_control_bulk API")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/2440edae7ca8534628cdbaf559ded288f2998178.1701276806.git.geert+renesas@glider.be
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Annotate struct reset_control_array with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct reset_control_array.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922175229.work.838-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

reset: ACPI reset support

Some of the IO devices like I2C or SPI require reset at runtime to
recover from an error condition without changing the power state of
the system. Added check for ACPI handle and a call to method '__RST'
if supported. Devices using device tree method are unaffected by this.

Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
[p.zabel@pengutronix.de: wrap in #ifdef CONFIG_ACPI due to missing stubs]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20220307135626.16673-1-kyarlagadda@nvidia.com

reset: bail if try_module_get() fails

Abort instead of returning a new reset control for a reset controller
device that is going to have its module unloaded.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Fixes: 61fc41317666 ("reset: Add reset controller API")
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210607082615.15160-1-p.zabel@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: whitespace fixes

Fixes checkpatch issues:

CHECK: Alignment should match open parenthesis
#87: FILE: drivers/reset/core.c:87:
+static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
+ const struct of_phandle_args *reset_spec)

CHECK: Lines should not end with a '('
#540: FILE: drivers/reset/core.c:540:
+static struct reset_control *__reset_control_get_internal(

CHECK: Alignment should match open parenthesis
#603: FILE: drivers/reset/core.c:603:
+struct reset_control *__of_reset_control_get(struct device_node *node,
+ const char *id, int index, bool shared,

CHECK: Alignment should match open parenthesis
#781: FILE: drivers/reset/core.c:781:
+struct reset_control *__devm_reset_control_get(struct device *dev,
+ const char *id, int index, bool shared,

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Add reset_control_bulk API

Follow the clock and regulator subsystems' lead and add a bulk API
for reset controls.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20210314154459.15375-5-digetx@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

reset: core: fix a kernel-doc markup

A function has a different name between their prototype
and its kernel-doc markup:

../drivers/reset/core.c:888: warning: expecting prototype for device_reset(). Prototype was for __device_reset() instead

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: make shared pulsed reset controls re-triggerable

The current reset framework API does not allow to release what is done by
reset_control_reset(), IOW decrement triggered_count. Add the new
reset_control_rearm() call to do so.

When reset_control_reset() has been called once, the counter
triggered_count, in the reset framework, is incremented i.e the resource
under the reset is in-use and the reset should not be done again.
reset_control_rearm() would be the way to state that the resource is
no longer used and, that from the caller's perspective, the reset can be
fired again if necessary.

Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
Reported-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Fix and extend kerneldoc

Fix W=1 compile warnings (invalid kerneldoc):

drivers/reset/core.c:50: warning: Function parameter or member 'array' not described in 'reset_control'
drivers/reset/core.c:50: warning: Function parameter or member 'deassert_count' not described in 'reset_control'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Align logic and flow in managed helpers

__devm_reset_control_get() and devm_reset_control_array_get() are very
similar, but they do not look similar, due to inverted logic.
Make them more similar, following the "bail out early" paradigm.

Adjust the logic and flow in devm_reset_controller_register() to match
the two other functions.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Do not register resource data for missing resets

When an optional reset is not present, __devm_reset_control_get() and
devm_reset_control_array_get() still register resource data to release
the non-existing reset on cleanup, which is futile.

Fix this by skipping NULL reset control pointers.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Fix {of,devm}_reset_control_array_get kerneldoc return types

of_reset_control_array_get() and devm_reset_control_array_get() return
struct reset_control pointers, not internal struct reset_control_array
pointers, just like all other reset control API calls.

Correct the kerneldoc to match the code.

Fixes: 17c82e206d2a3cd8 ("reset: Add APIs to manage array of resets")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: improve of_xlate documentation

Mention of_reset_simple_xlate as the default if of_xlate is not set.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: fix of_reset_control_get_count kerneldoc comment

Add a newline and remove a superfluous kerneldoc marker before the
of_reset_control_get_count kerneldoc comment, to fix documentation
build warnings:

./drivers/reset/core.c:832: warning: Incorrect use of kernel-doc format: * of_reset_control_get_count - Count number of resets available with a device
./drivers/reset/core.c:840: warning: Function parameter or member 'node' not described in 'of_reset_control_get_count'

Fixes: 17c82e206d2a ("reset: Add APIs to manage array of resets")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: fix of_reset_simple_xlate kerneldoc comment

The flags parameter never made it into the API, but was erroneously
included in the kerneldoc comment. Remove it to fix a documentation
build warning:

./drivers/reset/core.c:86: warning: Excess function parameter 'flags' description in 'of_reset_simple_xlate'

Fixes: 61fc41317666 ("reset: Add reset controller API")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Fix memory leak in reset_control_array_put()

Memory allocated for 'struct reset_control_array' in
of_reset_control_array_get() is never freed in
reset_control_array_put() resulting in kmemleak showing
the following backtrace.

backtrace:
[<00000000c5f17595>] __kmalloc+0x1b0/0x2b0
[<00000000bd499e13>] of_reset_control_array_get+0xa4/0x180
[<000000004cc02754>] 0xffff800008c669e4
[<0000000050a83b24>] platform_drv_probe+0x50/0xa0
[<00000000d3a0b0bc>] really_probe+0x108/0x348
[<000000005aa458ac>] driver_probe_device+0x58/0x100
[<000000008853626c>] device_driver_attach+0x6c/0x90
[<0000000085308d19>] __driver_attach+0x84/0xc8
[<00000000080d35f2>] bus_for_each_dev+0x74/0xc8
[<00000000dd7f015b>] driver_attach+0x20/0x28
[<00000000923ba6e6>] bus_add_driver+0x148/0x1f0
[<0000000061473b66>] driver_register+0x60/0x110
[<00000000c5bec167>] __platform_driver_register+0x40/0x48
[<000000007c764b4f>] 0xffff800008c6c020
[<0000000047ec2e8c>] do_one_initcall+0x5c/0x1b0
[<0000000093d4b50d>] do_init_module+0x54/0x1d0

Fixes: 17c82e206d2a ("reset: Add APIs to manage array of resets")
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Remove copy'n'paste redundancy in the comments

It seems the commit bb475230b8e5
("reset: make optional functions really optional")
brought couple of redundant lines in the comments.

Drop them here.

Cc: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: remove redundant null check on pointer dev

Pointer dev is being dereferenced when passed to the inlined
functon dev_name, however, dev is later being null checked
so at first this seems like a potential null pointer dereference.

In fact, _reset_control_get_from_lookup is only ever called from
__reset_control_get, right after checking dev->of_node hence
dev can never be null. Clean this up by removing the redundant
null check.

Thanks to Philipp Zabel for spotting that dev can never be null.

Addresses-Coverity: ("Dereference before null check")
Fixes: 6691dffab0ab ("reset: add support for non-DT systems")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

reset: Add acquire/release support for arrays

Add implementations that apply acquire and release operations to all
reset controls part of a reset control array.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Add acquired flag to of_reset_control_array_get()

In order to be able to request an array of reset controls in acquired or
released mode, add the acquired flag to of_reset_control_array_get() and
pass the flag to subsequent calls of __of_reset_control_get().

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: add acquired/released state for exclusive reset controls

There are cases where a driver needs explicit control over a reset line
that is exclusively conneted to its device, but this control has to be
temporarily handed over to the power domain controller to handle reset
requirements during power transitions.
Allow multiple exclusive reset controls to be requested in 'released'
state for the same physical reset line, only one of which can be
acquired at the same time.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>

reset: fix null pointer dereference on dev by dev_name

The call to dev_name will dereference dev, however, dev is later
being null checked, so there is a possibility of a null pointer
dereference on dev by the call to dev_name. Fix this by null
checking dev first before the call to dev_name

Detected by CoverityScan, CID#1475475 ("Dereference before null check")

Fixes: 2a6cb2b1d83b ("reset: Add reset_control_get_count()")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Add reset_control_get_count()

Currently the reset core has internal support for counting the number of
resets for a device described in DT. Generalize this to devices using
lookup resets, and export it for public use.

This will be used by generic drivers that need to be sure a device is
controlled by a single, dedicated reset line (e.g. vfio-platform).

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[p.zabel@pengutronix.de: fixed a typo in reset_control_get_count comment]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Fix potential use-after-free in __of_reset_control_get()

Calling of_node_put() decreases the reference count of a device tree
object, and may free some data.

However, the of_phandle_args structure embedding it is passed to
reset_controller_dev.of_xlate() after that, so it may still be accessed.

Move the call to of_node_put() down to fix this.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[p.zabel@pengutronix.de: moved of_node_put after mutex_unlock]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

treewide: Use struct_size() for kmalloc()-family

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
int stuff;
void *entry[];
};

instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);

This patch makes the changes for kmalloc()-family (and kvmalloc()-family)
uses. It was done via automatic conversion with manual review for the
"CHECKME" non-standard cases noted below, using the following Coccinelle
script:

// pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len *
// sizeof *pkey_cache->table, GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// Same pattern, but can't trivially locate the trailing element name,
// or variable name.
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
expression SOMETHING, COUNT, ELEMENT;
@@

- alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP)
+ alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP)

Signed-off-by: Kees Cook <keescook@chromium.org>

reset: modify the way reset lookup works for board files

Commit 7af1bb19f1d7 ("reset: add support for non-DT systems")
introduced reset control lookup mechanism for boards that still use
board files.

The routine used to register lookup entries takes the corresponding
reset_controlled_dev structure as argument.

It's been determined however that for the first user of this new
interface - davinci psc driver - it will be easier to register the
lookup entries using the reset controller device name.

This patch changes the way lookup entries are added.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
[p.zabel@pengutronix.de: added missing ERR_PTR]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: add support for non-DT systems

The reset framework only supports device-tree. There are some platforms
however, which need to use it even in legacy, board-file based mode.

An example of such architecture is the DaVinci family of SoCs which
supports both device tree and legacy boot modes and we don't want to
introduce any regressions.

We're currently working on converting the platform from its hand-crafted
clock API to using the common clock framework. Part of the overhaul will
be representing the chip's power sleep controller's reset lines using
the reset framework.

This changeset extends the core reset code with a new reset lookup
entry structure. It contains data allowing the reset core to associate
reset lines with devices by comparing the dev_id and con_id strings.

It also provides a function allowing drivers to register lookup entries
with the framework.

The new lookup function is only called as a fallback in case the
of_node field is NULL and doesn't change anything for current users.

Tested with a dummy reset driver with several lookup entries.

An example lookup table registration from a driver can be found below:

static struct reset_control_lookup foobar_reset_lookup[] = {
RESET_LOOKUP("foo.0", "foo", 15),
RESET_LOOKUP("bar.0", NULL, 5),
};

foobar_probe()
{
...

reset_controller_add_lookup(&rcdev, foobar_reset_lookup,
ARRAY_SIZE(foobar_reset_lookup));

...
}

Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: David Lechner <david@lechnology.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: make device_reset_optional() really optional

Commit bb475230b8e5 ("reset: make optional functions really optional")
converted *_get_optional* functions, but device_reset_optional() was
left behind. Convert it in the same way.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: make (de)assert report success for self-deasserting reset drivers

By now there are drivers using shared reset controls and (de)assert
calls on platforms with self-deasserting reset lines and thus reset
drivers that do not implement .assert() and .deassert().
As long as the initial state of the reset line is deasserted, there
is no reason for a reset_control_assert call to return an error for
shared reset controls, or for a reset_control_deassert call to return
an error for either shared or exclusive reset controls: after a call
to reset_control_deassert the reset line is guaranteed to be deasserted,
and after a call to reset_control_assert it is valid for the reset
line to stay deasserted for shared reset controls.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

reset: Add APIs to manage array of resets

Many devices may want to request a bunch of resets and control them. So
it's better to manage them as an array. Add APIs to _get() an array of
reset_control, reusing the _assert(), _deassert(), and _reset() APIs for
single reset controls. Since reset controls already may control multiple
reset lines with a single hardware bit, from the user perspective, reset
control arrays are not at all different from single reset controls.
Note that these APIs don't guarantee that the reset lines managed in the
array are handled in any particular order.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
[p.zabel@pengutronix.de: changed API to hide reset control arrays behind
struct reset_control]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: use kref for reference counting

Use kref for reference counting and enjoy the advantages of refcount_t.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: add exported __reset_control_get, return NULL if optional

Rename the internal __reset_control_get/put functions to
__reset_control_get/put_internal and add an exported
__reset_control_get equivalent to __of_reset_control_get
that takes a struct device parameter.
This avoids the confusing call to __of_reset_control_get in
the non-DT case and fixes the devm_reset_control_get_optional
function to return NULL if RESET_CONTROLLER is enabled but
dev->of_node == NULL.

Fixes: bb475230b8e5 ("reset: make optional functions really optional")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: fix shared reset triggered_count decrement on error

For a shared reset, when the reset is successful, the triggered_count is
incremented when trying to call the reset callback, so that another device
sharing the same reset line won't trigger it again. If the reset has not
been triggered successfully, the trigger_count should be decremented.

The code does the opposite, and decrements the trigger_count on success.
As a consequence, another device sharing the reset will be able to trigger
it again.

Fixed be removing negation in from of the error code of the reset function.

Fixes: 7da33a37b48f ("reset: allow using reset_control_reset with shared reset")

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: core: fix reset_control_put

Commit "reset: make optional functions really optional" missed to
adjust one check in reset_control_put, causing a NULL pointer
access for optional resets.

Fixes: bb475230b8e5 "reset: make optional functions really optional"
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: make optional functions really optional

The *_get_optional_* functions weren't really optional so this patch
makes them really optional.

These *_get_optional_* functions will now return NULL instead of an error
if no matching reset phandle is found in the DT, and all the
reset_control_* functions now accept NULL rstc pointers.

Signed-off-by: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Change shared flag from int to bool

Since the new parameter being added is going to be a bool this patch
changes the shared flag from int to bool to match the new parameter.

Signed-off-by: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: allow using reset_control_reset with shared reset

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: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: warn on invalid input to reset_control_reset/assert/deassert/status

Instead of potentially crashing, dump a backtrace and return -EINVAL if
rstc is NULL or an error code.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: add devm_reset_controller_register API

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: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Add support for shared reset controls

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: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Share struct reset_control between reset_control_get calls

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: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Make [of_]reset_control_get[_foo] functions wrappers

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: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Move DT cell size check to the core

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: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: remove unnecessary local variable initialization from of_reset_control_get_by_index

There is no need to initialize rstc, as it is unconditionally
assigned the return value of a kzalloc call before use.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: remove unused device pointer from struct reset_control

Commit 0c5b2b915a58 ("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: Philipp Zabel <p.zabel@pengutronix.de>

reset: use ENOTSUPP instead of ENOSYS

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: Philipp Zabel <p.zabel@pengutronix.de>

reset: Fix of_reset_control_get() for consistent return values

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: Alban Bedel <albeu@free.fr>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: add of_reset_control_get_by_index()

Add of_reset_control_get_by_index() to allow the drivers to get reset
device without knowing its name.

Signed-off-by: Vince 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: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: add reset_control_status helper function

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: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Add of_reset_control_get

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: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Mark function as static and remove unused function in core.c

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: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: allow drivers to request probe deferral

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: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Stephen Warren <swarren@nvidia.com>

reset: NULL deref on allocation failure

"rstc" is NULL here and we should use "rcdev" instead of "rstc->rcdev".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

reset: Add reset controller API

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: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Pavel Machek <pavel@ucw.cz>