Add a interface pinctrl_provide_dummies for platform to indicate
whether it needs use pinctrl dummy state.

ChangeLog v3->v4:
* remove dummy gpio support in pinctrl subsystem.
  Let gpio driver decide whether it wants to use pinctrl gpio mux
  function.
ChangeLog v2->v3:
* Also changed the missed pinctrl gpio APIs in v1.
ChangeLog v1->v2:
* Based on sascha's suggestion, drop using kconfig since it will hide
  pinctrl errors on all other boards.
  See: https://lkml.org/lkml/2012/4/18/282
  It seemed both Linus and Stephen agreed with this way, so i'm ok
  with it too.
* Add dummy gpio support.
  pinctrl gpio in the same situation as state.
* Patch name changed.
  Original is pinctrl: handle dummy state in core.
* Split removing old dt dummy interface into a separate patch

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: NStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

There are a few places in the api where the code simply returns -EINVAL when
it finds an error. An example is pinmux_map_to_setting() which now reports an
error if we try to match a group with a function that it does not support.

The reporting of errors in pinconf_check_ops and pinmux_check_ops now has the
same style and is located inside the according functions and not the calling
code.

When the map is found in the DT but the default state can not be selected we
get an error to know that the code at least tried.

The patch also removes a stray word from one comment and a "->" from another
for the sake of consistency.

Finally we replace a few pr_err/debug() calls with dev_err/dbg().

Thanks go to Stephen Warren for reviewing the patch and enhancing the reporting
inside pinmux_map_to_setting().
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Acked-by: NStephen Warren <swarren@wwwdotorg.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

pinctrl_register_map() was returning early if pinmux_validate_map() or
pinconf_validate_map() failed, but was not actually returning the error
code.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Pin name is more useful to users.

After change, when cat pingroups in sysfs, it becomes:
root@freescale /sys/kernel/debug/pinctrl/20e0000.iomuxc$ cat pingroups
registered pin groups:
group: uart4grp-1
pin 219 (MX6Q_PAD_KEY_ROW0)
pin 218 (MX6Q_PAD_KEY_COL0)

group: usdhc4grp-1
pin 305 (MX6Q_PAD_SD4_CMD)
pin 306 (MX6Q_PAD_SD4_CLK)
pin 315 (MX6Q_PAD_SD4_DAT0)
pin 316 (MX6Q_PAD_SD4_DAT1)
pin 317 (MX6Q_PAD_SD4_DAT2)
pin 318 (MX6Q_PAD_SD4_DAT3)
pin 319 (MX6Q_PAD_SD4_DAT4)
pin 320 (MX6Q_PAD_SD4_DAT5)
pin 321 (MX6Q_PAD_SD4_DAT6)
pin 322 (MX6Q_PAD_SD4_DAT7)
Acked-by: NStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

These functions allow the driver core to automatically clean up any
allocations made by drivers, thus leading to simplified drivers.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

If drivers try to obtain pinctrl handles for a pin controller that
has not yet registered to the subsystem, we need to be able to
back out and retry with deferred probing. So let's return
-EPROBE_DEFER whenever this location fails. Also downgrade the
errors to info, maybe we will even set them to debug once the
deferred probing is commonplace.

Cc: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: NStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Most of the SoC drivers implement list_groups() and list_functions()
routines for pinctrl and pinmux. These routines continue returning
zero until the selector argument is greater than total count of
available groups or functions.

This patch replaces these list_*() routines with get_*_count()
routines, which returns the number of available selection for SoC
driver. pinctrl layer will use this value to check the range it can
choose.

This patch fixes all user drivers for this change. There are other
routines in user drivers, which have checks to check validity of
selector passed to them. It is also no more required and hence
removed.

Documentation updated as well.
Acked-by: NStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: NViresh Kumar <viresh.kumar@st.com>
[Folded in fix and fixed a minor merge artifact manually]
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

During pinctrl_get(), if the client device has a device tree node, look
for the common pinctrl properties there. If found, parse the referenced
device tree nodes, with the help of the pinctrl drivers, and generate
mapping table entries from them.

During pinctrl_put(), free any results of device tree parsing.
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Most code assumes that the pinctrl ops are present. Validate this when
registering a pinctrl driver. Remove the one place in the code that
was checking whether one of these non-optional ops was present.
Signed-off-by: NStephen Warren <swarren@wwwdotorg.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

The pinctrl mapping table can now contain entries to:
* Set the mux function of a pin group
* Apply a set of pin config options to a pin or a group

This allows pinctrl_select_state() to apply pin configs settings as well
as mux settings.

v3: Fix find_pinctrl() to iterate over the correct list.
   s/_MUX_CONFIGS_/_CONFIGS_/ in mapping table macros.
   Fix documentation to use correct mapping table macro.
v2: Added numerous extra PIN_MAP_*() special-case macros.
   Fixed kerneldoc typo. Delete pinctrl_get_pin_id() and
   replace it with pin_get_from_name(). Various minor fixes.
   Updates due to rebase.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

The API model is changed from:

p = pinctrl_get(dev, "state1");
pinctrl_enable(p);
...
pinctrl_disable(p);
pinctrl_put(p);
p = pinctrl_get(dev, "state2");
pinctrl_enable(p);
...
pinctrl_disable(p);
pinctrl_put(p);

to this:

p = pinctrl_get(dev);
s1 = pinctrl_lookup_state(p, "state1");
s2 = pinctrl_lookup_state(p, "state2");
pinctrl_select_state(p, s1);
...
pinctrl_select_state(p, s2);
...
pinctrl_put(p);

This allows devices to directly transition between states without
disabling the pin controller programming and put()/get()ing the
configuration data each time. This model will also better suit pinconf
programming, which doesn't have a concept of "disable".

The special-case hogging feature of pin controllers is re-written to use
the regular APIs instead of special-case code. Hence, the pinmux-hogs
debugfs file is removed; see the top-level pinctrl-handles files for
equivalent data.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This change separates two aspects of struct pinctrl:

a) The data representation of the parsed mapping table, into:

   1) The top-level struct pinctrl object, a single entity returned
      by pinctrl_get().

   2) The parsed version of each mapping table entry, struct
      pinctrl_setting, of which there is one per mapping table entry.

b) The code that handles this; the code for (1) above is in core.c, and
   the code to parse/execute each entry in (2) above is in pinmux.c, while
   the iteration over multiple settings is lifted to core.c.

This will allow the following future changes:

1) pinctrl_get() API rework, so that struct pinctrl represents all states
   for the device, and the device can select between them without calling
   put()/get() again.

2) To support that, a struct pinctrl_state object will be inserted into
   the data model between the struct pinctrl and struct pinctrl_setting.

3) The mapping table will be extended to allow specification of pin config
   settings too. To support this, struct pinctrl_setting will be enhanced
   to store either mux settings or config settings, and functions will be
   added to pinconf.c to parse/execute pin configuration settings.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

There are many problems with the current pinctrl locking:

struct pinctrl_dev's gpio_ranges_lock isn't effective;
pinctrl_match_gpio_range() only holds this lock while searching for a gpio
range, but the found range is return and manipulated after releading the
lock. This could allow pinctrl_remove_gpio_range() for that range while it
is in use, and the caller may very well delete the range after removing it,
causing pinctrl code to touch the now-free range object.

Solving this requires the introduction of a higher-level lock, at least
a lock per pin controller, which both gpio range registration and
pinctrl_get()/put() will acquire.

There is missing locking on HW programming; pin controllers may pack the
configuration for different pins/groups/config options/... into one
register, and hence have to read-modify-write the register. This needs to
be protected, but currently isn't. Related, a future change will add a
"complete" op to the pin controller drivers, the idea being that each
state's programming will be programmed into the pinctrl driver followed
by the "complete" call, which may e.g. flush a register cache to HW. For
this to work, it must not be possible to interleave the pinctrl driver
calls for different devices.

As above, solving this requires the introduction of a higher-level lock,
at least a lock per pin controller, which will be held for the duration
of any pinctrl_enable()/disable() call.

However, each pinctrl mapping table entry may affect a different pin
controller if necessary. Hence, with a per-pin-controller lock, almost
any pinctrl API may need to acquire multiple locks, one per controller.
To avoid deadlock, these would need to be acquired in the same order in
all cases. This is extremely difficult to implement in the case of
pinctrl_get(), which doesn't know which pin controllers to lock until it
has parsed the entire mapping table, since it contains somewhat arbitrary
data.

The simplest solution here is to introduce a single lock that covers all
pin controllers at once. This will be acquired by all pinctrl APIs.

This then makes struct pinctrl's mutex irrelevant, since that single lock
will always be held whenever this mutex is currently held.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

pinctrl_register_mappings() already requires that every mapping table
entry have a non-NULL name field.

Logically, this makes sense too; drivers should always request a specific
named state so they know what they're getting. Relying on getting the
first mentioned state in the mapping table is error-prone, and a nasty
special case to implement, given that a given the mapping table may define
multiple states for a device.

Remove a small part of the documentation that talked about optionally
requesting a specific state; it's mandatory now.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This provides a single centralized name for the default state.

Update PIN_MAP_* macros to use this state name, instead of requiring the
user to pass a state name in.

With this change, hog entries in the mapping table are defined as those
with state name PINCTRL_STATE_DEFAULT, i.e. all entries have the same
name. This interacts badly with the nested iteration over mapping table
entries in pinctrl_hog_maps() and pinctrl_hog_map() which would now
attempt to claim each hog mapping table entry multiple times. Replacing
the custom hog code with a simple pinctrl_get()/pinctrl_enable().

Update documentation and mapping tables to use this.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

The debugfs file pinctrl-maps is a system-wide file, not specific to any
pin controller, so place it in the top-level directory.

Also, move the code implementing the file to keep the order of all the
functions matching the order they're created in pinctrl_init_*debugfs().
The only non-obvious change here is no private data is passed to
debugfs_create_file() or single_open().
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

struct pinctrl_dev's pin_desc_tree_lock and pinctrl_hogs_lock aren't
useful; the data they protect is read-only except when registering or
unregistering a pinctrl_dev, and at those times, it doesn't make sense to
protect one part of the structure independently from the rest.

Move pinctrl_init_device_debugfs() to the end of pinctrl_register() so
that debugfs can't access the struct pinctrl_dev until it's fully
initialized, i.e. after the hogs are set up.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This hopefully makes it harder to take the sizeof the wrong type.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

e.g. dev_err instead of pr_err prints messages in a slightly more
standardized format.

Also, add a few more error messages to track down errors.

Also, some small cleanups of messages.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Hog entries are mapping table entries with .ctrl_dev_name == .dev_name.
All other mapping table entries need .dev_name set so that they will
match some pinctrl_get() call. All extant PIN_MAP*() macros set
.dev_name.

So, there is no reason to allow mapping table entries without .dev_name
set. Update the code and documentation to disallow this.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This is a serious error, and the pin control system will not function
correctly if it ends up not programing the mapping table entries into
the HW. Instead of just ignoring this, error out.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
[rebased to fit the applied patch series, cast error to pointer]
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This may be perfectly legitimate. An IP block may get re-used
across SoCs. Not all of those SoCs may need pinmux settings for the
IP block, e.g. if one SoC dedicates pins to that function but
another doesn't. The driver won't know this, and will always
attempt to set up the pinmux. The mapping table defines whether any
HW programming is actually needed.
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NStephen Warren <swarren@nvidia.com>
[rebased to fit the applied patch series]
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

These are already disallowed. Clean up some code that doesn't assume this.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

* Make all functions internal to core.c static. Remove any of these from
  core.h.
* Add any missing EXPORT_SYMBOL_GPL().
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Instead of storing a single array of mapping table entries, which
requires realloc()ing that array each time it's extended and copying
the new data, simply store a list of pointers to the individual chunks.
This also removes the need to copy the mapping table at all; a pointer
is maintained to the original table, this saving memory.

A macro for_each_maps() is introduced to hide the additional complexity
of iterating over the map entries.

This change will also simplify removing chunks of entries from the mapping
table. This isn't important right now, but will be in the future, when
mapping table entries are dynamically added when parsing them from the
device tree, and removed when drivers no longer need to interact with
pinctrl.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This mostly makes debugfs files print things in the order that they
were added or acquired, which just feels a little more consistent.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

It may be common for pinctrl_register_mappings() to be used from __init
context, but there's no reason that additional mappings shouldn't be
added at a later point, e.g. if loading modules that add pin controllers
and their mapping tables.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Commit 77a59883 "pinctrl: changes hog mechanism to be self-referential"
modified the way "hog" entries were represented in the mapping table.
However, the new representation failed some error checks in
pinctrl_hog_map(). Remove the now-bogus error-check, and fix the code
to solve the issue the error-check used to avoid.
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Instead of a specific boolean field to indicate if a map entry shall
be hogged, treat self-reference as an indication of desired hogging.
This drops one field off the map struct and has a nice Douglas R.
Hofstadter-feel to it.
Acked-by: NDong Aisheng <dong.aisheng@linaro.org>
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This moves the per-devices struct pinctrl handles and device map
over from the pinmux part of the subsystem to the core pinctrl part.
This makes the device handles core infrastructure with the goal of
using these handles also for pin configuration, so that device
drivers (or boards etc) will need one and only one handle to the
pin control core.
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Since we want to use the former pinmux handles and mapping tables for
generic control involving both muxing and configuration we begin
refactoring by renaming them from pinmux_* to pinctrl_*.

ChangeLog v1->v2:
- Also rename the PINMUX_* macros in machine.h to PIN_ as indicated
  in the documentation so as to reflect the generic nature of these
  mapping entries from now on.
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

After discussion with Mark Brown in an unrelated thread about
ADC lookups, it came to my knowledge that the ability to pass
a struct device * in the regulator consumers is just a
historical artifact, and not really recommended. Since there
are no in-kernel users of these pointers, we just kill them
right now, before someone starts to use them.
Reviewed-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Commit ca53c5f1
("pinctrl: conjure names for unnamed pins") made pins lose
their identity and only get autogenerated names.
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This is needed as otherwise we can get the following when
dealing with buggy data in a pinmux driver for
pinmux_search_function:

Unable to handle kernel NULL pointer dereference at virtual
address 00000000
...
PC is at strcmp+0xc/0x34
LR is at pinmux_get+0x350/0x8f4
...

As we need pctldev initialized to call ops->list_functions,
let's initialize it before check_ops calls and pass the
pctldev to the check_ops functions. Do this for both pinmux
and pinconf check_ops functions.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

We were not cleaning up properly after unloading a pinmux
driver compiled as module.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This patch removes maxpin member in the pin control descriptor
because we don't need this value as we enumerate a pin space
using offset.
Signed-off-by: NChanho Park <chanho61.park@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This patch modifies a offset while enumerating pins to support a
partial pin space. If we use a pin number for enumerating pins,
the pin space always starts with zero base. Indeed, we always check
the pin is in the pin space. An extreme example, there is only two pins.
One is 0. Another is 1000. We always enumerate whole offsets until 1000.
For solving this problem, we use the offset of the pin array instead
of the zero-based pin number.
Signed-off-by: NChanho Park <chanho61.park@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
[Restored sparse pin space comment]
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

If pins with blank names are registered, we assign them names on-the-fly
on the form "PINn" where n is the pin number for that pin on the specific
controller.
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Pin controllers should already be instantiated as a device, so there's
no need for the pinctrl core to create a new struct device for each
controller.

This allows the controller's real name to be used in the mux mapping
table, rather than e.g. "pinctrl.0", "pinctrl.1", etc.

This necessitates removal of the PINMUX_MAP_PRIMARY*() macros, since
their sole purpose was to hard-code the .ctrl_dev_name field to be
"pinctrl.0".
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This add per-pin and per-group pin config interfaces for biasing,
driving and other such electronic properties. The details of passed
configurations are passed in an opaque unsigned long which may be
dereferences to integer types, structs or lists on either side
of the configuration interface.

ChangeLog v1->v2:
- Clear split of terminology: we now have pin controllers, and
  those may support two interfaces using vtables: pin
  multiplexing and pin configuration.
- Break out pin configuration to its own C file, controllers may
  implement only config without mux, and vice versa, so keep each
  sub-functionality of pin controllers separate. Introduce
  CONFIG_PINCONF in Kconfig.
- Implement some core logic around pin configuration in the
  pinconf.c file.
- Remove UNKNOWN config states, these were just surplus baggage.
- Remove FLOAT config state - HIGH_IMPEDANCE should be enough for
  everyone.
- PIN_CONFIG_POWER_SOURCE added to handle switching the power
  supply for the pin logic between different sources
- Explicit DISABLE config enums to turn schmitt-trigger,
  wakeup etc OFF.
- Update documentation to reflect all the recent reasoning.
ChangeLog v2->v3:
- Twist API around to pass around arrays of config tuples instead
  of (param, value) pairs everywhere.
- Explicit drive strength semantics for push/pull and similar
  drive modes, this shall be the number of drive stages vs
  nominal load impedance, which should match the actual
  electronics used in push/pull CMOS or TTY totempoles.
- Drop load capacitance configuration - I probably don't know
  what I'm doing here so leave it out.
- Drop PIN_CONFIG_INPUT_SCHMITT_OFF, instead the argument zero to
  PIN_CONFIG_INPUT_SCHMITT turns schmitt trigger off.
- Drop PIN_CONFIG_NORMAL_POWER_MODE and have a well defined
  argument to PIN_CONFIG_LOW_POWER_MODE to get out of it instead.
- Drop PIN_CONFIG_WAKEUP_ENABLE/DISABLE and just use
  PIN_CONFIG_WAKEUP with defined value zero to turn wakeup off.
- Add PIN_CONFIG_INPUT_DEBOUNCE for configuring debounce time
  on input lines.
- Fix a bug when we tried to configure pins for pin controllers
  without pinconf support.
- Initialized debugfs properly so it works.
- Initialize the mutex properly and lock around config tampering
  sections.
- Check the return value from get_initial_config() properly.
ChangeLog v3->v4:
- Export the pin_config_get(), pin_config_set() and
  pin_config_group() functions.
- Drop the entire concept of just getting initial config and
  keeping track of pin states internally, instead ask the pins
  what state they are in. Previous idea was plain wrong, if the
  device cannot keep track of its state, the driver should do
  it.
- Drop the generic configuration layout, it seems this impose
  too much restriction on some pin controllers, so let them do
  things the way they want and split off support for generic
  config as an optional add-on.
ChangeLog v4->v5:
- Introduce two symmetric driver calls for group configuration,
  .pin_config_group_[get|set] and corresponding external calls.
- Remove generic semantic meanings of return values from config
  calls, these belong in the generic config patch. Just pass the
  return value through instead.
- Add a debugfs entry "pinconf-groups" to read status from group
  configuration only, also slam in a per-group debug callback in
  the pinconf_ops so custom drivers can display something
  meaningful for their pins.
- Fix some dangling newline.
- Drop dangling #else clause.
- Update documentation to match the above.
ChangeLog v5->v6:
- Change to using a pin name as parameter for the
  [get|set]_config() functions, as suggested by Stephen Warren.
  This is more natural as names will be what a developer has
  access to in written documentation etc.
ChangeLog v6->v7:
- Refactor out by-pin and by-name get/set functions, only expose
  the by-name functions externally, expose the by-pin functions
  internally.
- Show supported pin control functionality in the debugfs
  pinctrl-devices file.
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>