drivers: create a pin control subsystem

This creates a subsystem for handling of pin control devices.
These are devices that control different aspects of package
pins.

Currently it handles pinmuxing, i.e. assigning electronic
functions to groups of pins on primarily PGA and BGA type of
chip packages which are common in embedded systems.

The plan is to also handle other I/O pin control aspects
such as biasing, driving, input properties such as
schmitt-triggering, load capacitance etc within this
subsystem, to remove a lot of ARM arch code as well as
feature-creepy GPIO drivers which are implementing the same
thing over and over again.

This is being done to depopulate the arch/arm/* directory
of such custom drivers and try to abstract the infrastructure
they all need. See the Documentation/pinctrl.txt file that is
part of this patch for more details.

ChangeLog v1->v2:

- Various minor fixes from Joe's and Stephens review comments
- Added a pinmux_config() that can invoke custom configuration
  with arbitrary data passed in or out to/from the pinmux driver

ChangeLog v2->v3:

- Renamed subsystem folder to "pinctrl" since we will likely
  want to keep other pin control such as biasing in this
  subsystem too, so let us keep to something generic even though
  we're mainly doing pinmux now.
- As a consequence, register pins as an abstract entity separate
  from the pinmux. The muxing functions will claim pins out of the
  pin pool and make sure they do not collide. Pins can now be
  named by the pinctrl core.
- Converted the pin lookup from a static array into a radix tree,
  I agreed with Grant Likely to try to avoid any static allocation
  (which is crap for device tree stuff) so I just rewrote this
  to be dynamic, just like irq number descriptors. The
  platform-wide definition of number of pins goes away - this is
  now just the sum total of the pins registered to the subsystem.
- Make sure mappings with only a function name and no device
  works properly.

ChangeLog v3->v4:

- Define a number space per controller instead of globally,
  Stephen and Grant requested the same thing so now maps need to
  define target controller, and the radix tree of pin descriptors
  is a property on each pin controller device.
- Add a compulsory pinctrl device entry to the pinctrl mapping
  table. This must match the pinctrl device, like "pinctrl.0"
- Split the file core.c in two: core.c and pinmux.c where the
  latter carry all pinmux stuff, the core is for generic pin
  control, and use local headers to access functionality between
  files. It is now possible to implement a "blank" pin controller
  without pinmux capabilities. This split will make new additions
  like pindrive.c, pinbias.c etc possible for combined drivers
  and chunks of functionality which is a GoodThing(TM).
- Rewrite the interaction with the GPIO subsystem - the pin
  controller descriptor now handles this by defining an offset
  into the GPIO numberspace for its handled pin range. This is
  used to look up the apropriate pin controller for a GPIO pin.
  Then that specific GPIO range is matched 1-1 for the target
  controller instance.
- Fixed a number of review comments from Joe Perches.
- Broke out a header file pinctrl.h for the core pin handling
  stuff that will be reused by other stuff than pinmux.
- Fixed some erroneous EXPORT() stuff.
- Remove mispatched U300 Kconfig and Makefile entries
- Fixed a number of review comments from Stephen Warren, not all
  of them - still WIP. But I think the new mapping that will
  specify which function goes to which pin mux controller address
  50% of your concerns (else beat me up).

ChangeLog v4->v5:

- Defined a "position" for each function, so the pin controller now
  tracks a function in a certain position, and the pinmux maps define
  what position you want the function in. (Feedback from Stephen
  Warren and Sascha Hauer).
- Since we now need to request a combined function+position from
  the machine mapping table that connect mux settings to drivers,
  it was extended with a position field and a name field. The
  name field is now used if you e.g. need to switch between two
  mux map settings at runtime.
- Switched from a class device to using struct bus_type for this
  subsystem. Verified sysfs functionality: seems to work fine.
  (Feedback from Arnd Bergmann and Greg Kroah-Hartman)
- Define a per pincontroller list of GPIO ranges from the GPIO
  pin space that can be handled by the pin controller. These can
  be added one by one at runtime. (Feedback from Barry Song)
- Expanded documentation of regulator_[get|enable|disable|put]
  semantics.
- Fixed a number of review comments from Barry Song. (Thanks!)

ChangeLog v5->v6:

- Create an abstract pin group concept that can sort pins into
  named and enumerated groups no matter what the use of these
  groups may be, one possible usecase is a group of pins being
  muxed in or so. The intention is however to also use these
  groups for other pin control activities.
- Make it compulsory for pinmux functions to associate with
  at least one group, so the abstract pin group concept is used
  to define the groups of pins affected by a pinmux function.
  The pinmux driver interface has been altered so as to enforce
  a function to list applicable groups per function.
- Provide an optional .group entry in the pinmux machine map
  so the map can select beteween different available groups
  to be used with a certain function.
- Consequent changes all over the place so that e.g. debugfs
  present reasonable information about the world.
- Drop the per-pin mux (*config) function in the pinmux_ops
  struct - I was afraid that this would start to be used for
  things totally unrelated to muxing, we can introduce that to
  the generic struct pinctrl_ops if needed. I want to keep
  muxing orthogonal to other pin control subjects and not mix
  these things up.

ChangeLog v6->v7:

- Make it possible to have several map entries matching the
  same device, pin controller and function, but using
  a different group, and alter the semantics so that
  pinmux_get() will pick all matching map entries, and
  store the associated groups in a list. The list will
  then be iterated over at pinmux_enable()/pinmux_disable()
  and corresponding driver functions called for each
  defined group. Notice that you're only allowed to map
  multiple *groups* to the same
  { device, pin controller, function } triplet, attempts
  to map the same device to multiple pin controllers will
  for example fail. This is hopefully the crucial feature
  requested by Stephen Warren.
- Add a pinmux hogging field to the pinmux mapping entries,
  and enable the pinmux core to hog pinmux map entries.
  This currently only works for pinmuxes without assigned
  devices as it looks now, but with device trees we can
  look up the corresponding struct device * entries when
  we register the pinmux driver, and have it hog each
  pinmux map in turn, for a simple approach to
  non-dynamic pin muxing. This addresses an issue from
  Grant Likely that the machine should take care of as
  much of the pinmux setup as possible, not the devices.
  By supplying a list of hogs, it can now instruct the
  core to take care of any static mappings.
- Switch pinmux group retrieveal function to grab an
  array of strings representing the groups rather than an
  array of unsigned and rewrite accordingly.
- Alter debugfs to show the grouplist handled by each
  pinmux. Also add a list of hogs.
- Dynamically allocate a struct pinmux at pinmux_get() and
  free it at pinmux_put(), then add these to the global
  list of pinmuxes active as we go along.
- Go over the list of pinmux maps at pinmux_get() time
  and repeatedly apply matches.
- Retrieve applicable groups per function from the driver
  as a string array rather than a unsigned array, then
  lookup the enumerators.
- Make the device to pinmux map a singleton - only allow the
  mapping table to be registered once and even tag the
  registration function with __init so it surely won't be
  abused.
- Create a separate debugfs file to view the pinmux map at
  runtime.
- Introduce a spin lock to the pin descriptor struct, lock it
  when modifying pin status entries. Reported by Stijn Devriendt.
- Fix up the documentation after review from Stephen Warren.
- Let the GPIO ranges give names as const char * instead of some
  fixed-length string.
- add a function to unregister GPIO ranges to mirror the
  registration function.
- Privatized the struct pinctrl_device and removed it from the
  <linux/pinctrl/pinctrl.h> API, the drivers do not need to know
  the members of this struct. It is now in the local header
  "core.h".
- Rename the concept of "anonymous" mux maps to "system" muxes
  and add convenience macros and documentation.

ChangeLog v7->v8:

- Delete the leftover pinmux_config() function from the
 <linux/pinctrl/pinmux.h> header.
- Fix a race condition found by Stijn Devriendt in pin_request()

ChangeLog v8->v9:

- Drop the bus_type and the sysfs attributes and all, we're not on
  the clear about how this should be used for e.g. userspace
  interfaces so let us save this for the future.
- Use the right name in MAINTAINERS, PIN CONTROL rather than
  PINMUX
- Don't kfree() the device state holder, let the .remove() callback
  handle this.
- Fix up numerous kerneldoc headers to have one line for the function
  description and more verbose documentation below the parameters

ChangeLog v9->v10:
- pinctrl: EXPORT_SYMBOL needs export.h, folded in a patch
  from Steven Rothwell
- fix pinctrl_register error handling, folded in a patch from
  Axel Lin
- Various fixes to documentation text so that it's consistent.
- Removed pointless comment from drivers/Kconfig
- Removed dependency on SYSFS since we removed the bus in
  v9.
- Renamed hopelessly abbreviated pctldev_* functions to the
  more verbose pinctrl_dev_*
- Drop mutex properly when looking up GPIO ranges
- Return NULL instead of ERR_PTR() errors on registration of
  pin controllers, using cast pointers is fragile. We can
  live without the detailed error codes for sure.

Cc: Stijn Devriendt <highguy@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Barry Song <21cnbao@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 1180 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
new file mode 100644
index 000000000000..6544d98b2cf8
--- /dev/null
+++ b/drivers/pinctrl/pinmux.c
@@ -0,0 +1,1180 @@
+/*
+ * Core driver for the pin muxing portions of the pin control subsystem
+ *
+ * Copyright (C) 2011 ST-Ericsson SA
+ * Written on behalf of Linaro for ST-Ericsson
+ * Based on bits of regulator core, gpio core and clk core
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+#define pr_fmt(fmt) "pinmux core: " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/sysfs.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/pinctrl/machine.h>
+#include <linux/pinctrl/pinmux.h>
+#include "core.h"
+
+/* List of pinmuxes */
+static DEFINE_MUTEX(pinmux_list_mutex);
+static LIST_HEAD(pinmux_list);
+
+/* List of pinmux hogs */
+static DEFINE_MUTEX(pinmux_hoglist_mutex);
+static LIST_HEAD(pinmux_hoglist);
+
+/* Global pinmux maps, we allow one set only */
+static struct pinmux_map const *pinmux_maps;
+static unsigned pinmux_maps_num;
+
+/**
+ * struct pinmux_group - group list item for pinmux groups
+ * @node: pinmux group list node
+ * @group_selector: the group selector for this group
+ */
+struct pinmux_group {
+	struct list_head node;
+	unsigned group_selector;
+};
+
+/**
+ * struct pinmux - per-device pinmux state holder
+ * @node: global list node
+ * @dev: the device using this pinmux
+ * @usecount: the number of active users of this mux setting, used to keep
+ *	track of nested use cases
+ * @pins: an array of discrete physical pins used in this mapping, taken
+ *	from the global pin enumeration space (copied from pinmux map)
+ * @num_pins: the number of pins in this mapping array, i.e. the number of
+ *	elements in .pins so we can iterate over that array (copied from
+ *	pinmux map)
+ * @pctldev: pin control device handling this pinmux
+ * @func_selector: the function selector for the pinmux device handling
+ *	this pinmux
+ * @groups: the group selectors for the pinmux device and
+ *	selector combination handling this pinmux, this is a list that
+ *	will be traversed on all pinmux operations such as
+ *	get/put/enable/disable
+ * @mutex: a lock for the pinmux state holder
+ */
+struct pinmux {
+	struct list_head node;
+	struct device *dev;
+	unsigned usecount;
+	struct pinctrl_dev *pctldev;
+	unsigned func_selector;
+	struct list_head groups;
+	struct mutex mutex;
+};
+
+/**
+ * struct pinmux_hog - a list item to stash mux hogs
+ * @node: pinmux hog list node
+ * @map: map entry responsible for this hogging
+ * @pmx: the pinmux hogged by this item
+ */
+struct pinmux_hog {
+	struct list_head node;
+	struct pinmux_map const *map;
+	struct pinmux *pmx;
+};
+
+/**
+ * pin_request() - request a single pin to be muxed in, typically for GPIO
+ * @pin: the pin number in the global pin space
+ * @function: a functional name to give to this pin, passed to the driver
+ *	so it knows what function to mux in, e.g. the string "gpioNN"
+ *	means that you want to mux in the pin for use as GPIO number NN
+ * @gpio: if this request concerns a single GPIO pin
+ * @gpio_range: the range matching the GPIO pin if this is a request for a
+ *	single GPIO pin
+ */
+static int pin_request(struct pinctrl_dev *pctldev,
+		       int pin, const char *function, bool gpio,
+		       struct pinctrl_gpio_range *gpio_range)
+{
+	struct pin_desc *desc;
+	const struct pinmux_ops *ops = pctldev->desc->pmxops;
+	int status = -EINVAL;
+
+	dev_dbg(&pctldev->dev, "request pin %d for %s\n", pin, function);
+
+	if (!pin_is_valid(pctldev, pin)) {
+		dev_err(&pctldev->dev, "pin is invalid\n");
+		return -EINVAL;
+	}
+
+	if (!function) {
+		dev_err(&pctldev->dev, "no function name given\n");
+		return -EINVAL;
+	}
+
+	desc = pin_desc_get(pctldev, pin);
+	if (desc == NULL) {
+		dev_err(&pctldev->dev,
+			"pin is not registered so it cannot be requested\n");
+		goto out;
+	}
+
+	spin_lock(&desc->lock);
+	if (desc->mux_requested) {
+		spin_unlock(&desc->lock);
+		dev_err(&pctldev->dev,
+			"pin already requested\n");
+		goto out;
+	}
+	desc->mux_requested = true;
+	strncpy(desc->mux_function, function, sizeof(desc->mux_function));
+	spin_unlock(&desc->lock);
+
+	/* Let each pin increase references to this module */
+	if (!try_module_get(pctldev->owner)) {
+		dev_err(&pctldev->dev,
+			"could not increase module refcount for pin %d\n",
+			pin);
+		status = -EINVAL;
+		goto out_free_pin;
+	}
+
+	/*
+	 * If there is no kind of request function for the pin we just assume
+	 * we got it by default and proceed.
+	 */
+	if (gpio && ops->gpio_request_enable)
+		/* This requests and enables a single GPIO pin */
+		status = ops->gpio_request_enable(pctldev, gpio_range, pin);
+	else if (ops->request)
+		status = ops->request(pctldev, pin);
+	else
+		status = 0;
+
+	if (status)
+		dev_err(&pctldev->dev, "->request on device %s failed "
+		       "for pin %d\n",
+		       pctldev->desc->name, pin);
+out_free_pin:
+	if (status) {
+		spin_lock(&desc->lock);
+		desc->mux_requested = false;
+		desc->mux_function[0] = '\0';
+		spin_unlock(&desc->lock);
+	}
+out:
+	if (status)
+		dev_err(&pctldev->dev, "pin-%d (%s) status %d\n",
+		       pin, function ? : "?", status);
+
+	return status;
+}
+
+/**
+ * pin_free() - release a single muxed in pin so something else can be muxed
+ * @pctldev: pin controller device handling this pin
+ * @pin: the pin to free
+ */
+static void pin_free(struct pinctrl_dev *pctldev, int pin)
+{
+	const struct pinmux_ops *ops = pctldev->desc->pmxops;
+	struct pin_desc *desc;
+
+	desc = pin_desc_get(pctldev, pin);
+	if (desc == NULL) {
+		dev_err(&pctldev->dev,
+			"pin is not registered so it cannot be freed\n");
+		return;
+	}
+
+	if (ops->free)
+		ops->free(pctldev, pin);
+
+	spin_lock(&desc->lock);
+	desc->mux_requested = false;
+	desc->mux_function[0] = '\0';
+	spin_unlock(&desc->lock);
+	module_put(pctldev->owner);
+}
+
+/**
+ * pinmux_request_gpio() - request a single pin to be muxed in as GPIO
+ * @gpio: the GPIO pin number from the GPIO subsystem number space
+ */
+int pinmux_request_gpio(unsigned gpio)
+{
+	char gpiostr[16];
+	struct pinctrl_dev *pctldev;
+	struct pinctrl_gpio_range *range;
+	int ret;
+	int pin;
+
+	ret = pinctrl_get_device_gpio_range(gpio, &pctldev, &range);
+	if (ret)
+		return -EINVAL;
+
+	/* Convert to the pin controllers number space */
+	pin = gpio - range->base;
+
+	/* Conjure some name stating what chip and pin this is taken by */
+	snprintf(gpiostr, 15, "%s:%d", range->name, gpio);
+
+	return pin_request(pctldev, pin, gpiostr, true, range);
+}
+EXPORT_SYMBOL_GPL(pinmux_request_gpio);
+
+/**
+ * pinmux_free_gpio() - free a single pin, currently used as GPIO
+ * @gpio: the GPIO pin number from the GPIO subsystem number space
+ */
+void pinmux_free_gpio(unsigned gpio)
+{
+	struct pinctrl_dev *pctldev;
+	struct pinctrl_gpio_range *range;
+	int ret;
+	int pin;
+
+	ret = pinctrl_get_device_gpio_range(gpio, &pctldev, &range);
+	if (ret)
+		return;
+
+	/* Convert to the pin controllers number space */
+	pin = gpio - range->base;
+
+	pin_free(pctldev, pin);
+}
+EXPORT_SYMBOL_GPL(pinmux_free_gpio);
+
+/**
+ * pinmux_register_mappings() - register a set of pinmux mappings
+ * @maps: the pinmux mappings table to register
+ * @num_maps: the number of maps in the mapping table
+ *
+ * Only call this once during initialization of your machine, the function is
+ * tagged as __init and won't be callable after init has completed. The map
+ * passed into this function will be owned by the pinmux core and cannot be
+ * free:d.
+ */
+int __init pinmux_register_mappings(struct pinmux_map const *maps,
+				    unsigned num_maps)
+{
+	int i;
+
+	if (pinmux_maps != NULL) {
+		pr_err("pinmux mappings already registered, you can only "
+		       "register one set of maps\n");
+		return -EINVAL;
+	}
+
+	pr_debug("add %d pinmux maps\n", num_maps);
+	for (i = 0; i < num_maps; i++) {
+		/* Sanity check the mapping */
+		if (!maps[i].name) {
+			pr_err("failed to register map %d: "
+			       "no map name given\n", i);
+			return -EINVAL;
+		}
+		if (!maps[i].ctrl_dev && !maps[i].ctrl_dev_name) {
+			pr_err("failed to register map %s (%d): "
+			       "no pin control device given\n",
+			       maps[i].name, i);
+			return -EINVAL;
+		}
+		if (!maps[i].function) {
+			pr_err("failed to register map %s (%d): "
+			       "no function ID given\n", maps[i].name, i);
+			return -EINVAL;
+		}
+
+		if (!maps[i].dev && !maps[i].dev_name)
+			pr_debug("add system map %s function %s with no device\n",
+				 maps[i].name,
+				 maps[i].function);
+		else
+			pr_debug("register map %s, function %s\n",
+				 maps[i].name,
+				 maps[i].function);
+	}
+
+	pinmux_maps = maps;
+	pinmux_maps_num = num_maps;
+
+	return 0;
+}
+
+/**
+ * acquire_pins() - acquire all the pins for a certain funcion on a pinmux
+ * @pctldev: the device to take the pins on
+ * @func_selector: the function selector to acquire the pins for
+ * @group_selector: the group selector containing the pins to acquire
+ */
+static int acquire_pins(struct pinctrl_dev *pctldev,
+			unsigned func_selector,
+			unsigned group_selector)
+{
+	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+	const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
+	const char *func = pmxops->get_function_name(pctldev,
+						     func_selector);
+	unsigned *pins;
+	unsigned num_pins;
+	int ret;
+	int i;
+
+	ret = pctlops->get_group_pins(pctldev, group_selector,
+				      &pins, &num_pins);
+	if (ret)
+		return ret;
+
+	dev_dbg(&pctldev->dev, "requesting the %u pins from group %u\n",
+		num_pins, group_selector);
+
+	/* Try to allocate all pins in this group, one by one */
+	for (i = 0; i < num_pins; i++) {
+		ret = pin_request(pctldev, pins[i], func, false, NULL);
+		if (ret) {
+			dev_err(&pctldev->dev,
+				"could not get pin %d for function %s "
+				"on device %s - conflicting mux mappings?\n",
+				pins[i], func ? : "(undefined)",
+				pinctrl_dev_get_name(pctldev));
+			/* On error release all taken pins */
+			i--; /* this pin just failed */
+			for (; i >= 0; i--)
+				pin_free(pctldev, pins[i]);
+			return -ENODEV;
+		}
+	}
+	return 0;
+}
+
+/**
+ * release_pins() - release pins taken by earlier acquirement
+ * @pctldev: the device to free the pinx on
+ * @group_selector: the group selector containing the pins to free
+ */
+static void release_pins(struct pinctrl_dev *pctldev,
+			 unsigned group_selector)
+{
+	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+	unsigned *pins;
+	unsigned num_pins;
+	int ret;
+	int i;
+
+	ret = pctlops->get_group_pins(pctldev, group_selector,
+				      &pins, &num_pins);
+	if (ret) {
+		dev_err(&pctldev->dev, "could not get pins to release for "
+			"group selector %d\n",
+			group_selector);
+		return;
+	}
+	for (i = 0; i < num_pins; i++)
+		pin_free(pctldev, pins[i]);
+}
+
+/**
+ * pinmux_get_group_selector() - returns the group selector for a group
+ * @pctldev: the pin controller handling the group
+ * @pin_group: the pin group to look up
+ */
+static int pinmux_get_group_selector(struct pinctrl_dev *pctldev,
+				     const char *pin_group)
+{
+	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+	unsigned group_selector = 0;
+
+	while (pctlops->list_groups(pctldev, group_selector) >= 0) {
+		const char *gname = pctlops->get_group_name(pctldev,
+							    group_selector);
+		if (!strcmp(gname, pin_group)) {
+			dev_dbg(&pctldev->dev,
+				"found group selector %u for %s\n",
+				group_selector,
+				pin_group);
+			return group_selector;
+		}
+
+		group_selector++;
+	}
+
+	dev_err(&pctldev->dev, "does not have pin group %s\n",
+		pin_group);
+
+	return -EINVAL;
+}
+
+/**
+ * pinmux_check_pin_group() - check function and pin group combo
+ * @pctldev: device to check the pin group vs function for
+ * @func_selector: the function selector to check the pin group for, we have
+ *	already looked this up in the calling function
+ * @pin_group: the pin group to match to the function
+ *
+ * This function will check that the pinmux driver can supply the
+ * selected pin group for a certain function, returns the group selector if
+ * the group and function selector will work fine together, else returns
+ * negative
+ */
+static int pinmux_check_pin_group(struct pinctrl_dev *pctldev,
+				  unsigned func_selector,
+				  const char *pin_group)
+{
+	const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
+	const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
+	int ret;
+
+	/*
+	 * If the driver does not support different pin groups for the
+	 * functions, we only support group 0, and assume this exists.
+	 */
+	if (!pctlops || !pctlops->list_groups)
+		return 0;
+
+	/*
+	 * Passing NULL (no specific group) will select the first and
+	 * hopefully only group of pins available for this function.
+	 */
+	if (!pin_group) {
+		char const * const *groups;
+		unsigned num_groups;
+
+		ret = pmxops->get_function_groups(pctldev, func_selector,
+						  &groups, &num_groups);
+		if (ret)
+			return ret;
+		if (num_groups < 1)
+			return -EINVAL;
+		ret = pinmux_get_group_selector(pctldev, groups[0]);
+		if (ret < 0) {
+			dev_err(&pctldev->dev,
+				"function %s wants group %s but the pin "
+				"controller does not seem to have that group\n",
+				pmxops->get_function_name(pctldev, func_selector),
+				groups[0]);
+			return ret;
+		}
+
+		if (num_groups > 1)
+			dev_dbg(&pctldev->dev,
+				"function %s support more than one group, "
+				"default-selecting first group %s (%d)\n",
+				pmxops->get_function_name(pctldev, func_selector),
+				groups[0],
+				ret);
+
+		return ret;
+	}
+
+	dev_dbg(&pctldev->dev,
+		"check if we have pin group %s on controller %s\n",
+		pin_group, pinctrl_dev_get_name(pctldev));
+
+	ret = pinmux_get_group_selector(pctldev, pin_group);
+	if (ret < 0) {
+		dev_dbg(&pctldev->dev,
+			"%s does not support pin group %s with function %s\n",
+			pinctrl_dev_get_name(pctldev),
+			pin_group,
+			pmxops->get_function_name(pctldev, func_selector));
+	}
+	return ret;
+}
+
+/**
+ * pinmux_search_function() - check pin control driver for a certain function
+ * @pctldev: device to check for function and position
+ * @map: function map containing the function and position to look for
+ * @func_selector: returns the applicable function selector if found
+ * @group_selector: returns the applicable group selector if found
+ *
+ * This will search the pinmux driver for an applicable
+ * function with a specific pin group, returns 0 if these can be mapped
+ * negative otherwise
+ */
+static int pinmux_search_function(struct pinctrl_dev *pctldev,
+				  struct pinmux_map const *map,
+				  unsigned *func_selector,
+				  unsigned *group_selector)
+{
+	const struct pinmux_ops *ops = pctldev->desc->pmxops;
+	unsigned selector = 0;
+
+	/* See if this pctldev has this function */
+	while (ops->list_functions(pctldev, selector) >= 0) {
+		const char *fname = ops->get_function_name(pctldev,
+							   selector);
+		int ret;
+
+		if (!strcmp(map->function, fname)) {
+			/* Found the function, check pin group */
+			ret = pinmux_check_pin_group(pctldev, selector,
+						     map->group);
+			if (ret < 0)
+				return ret;
+
+			/* This function and group selector can be used */
+			*func_selector = selector;
+			*group_selector = ret;
+			return 0;
+
+		}
+		selector++;
+	}
+
+	pr_err("%s does not support function %s\n",
+	       pinctrl_dev_get_name(pctldev), map->function);
+	return -EINVAL;
+}
+
+/**
+ * pinmux_enable_muxmap() - enable a map entry for a certain pinmux
+ */
+static int pinmux_enable_muxmap(struct pinctrl_dev *pctldev,
+				struct pinmux *pmx,
+				struct device *dev,
+				const char *devname,
+				struct pinmux_map const *map)
+{
+	unsigned func_selector;
+	unsigned group_selector;
+	struct pinmux_group *grp;
+	int ret;
+
+	/*
+	 * Note that we're not locking the pinmux mutex here, because
+	 * this is only called at pinmux initialization time when it
+	 * has not been added to any list and thus is not reachable
+	 * by anyone else.
+	 */
+
+	if (pmx->pctldev && pmx->pctldev != pctldev) {
+		dev_err(&pctldev->dev,
+			"different pin control devices given for device %s, "
+			"function %s\n",
+			devname,
+			map->function);
+		return -EINVAL;
+	}
+	pmx->dev = dev;
+	pmx->pctldev = pctldev;
+
+	/* Now go into the driver and try to match a function and group */
+	ret = pinmux_search_function(pctldev, map, &func_selector,
+				     &group_selector);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * If the function selector is already set, it needs to be identical,
+	 * we support several groups with one function but not several
+	 * functions with one or several groups in the same pinmux.
+	 */
+	if (pmx->func_selector != UINT_MAX &&
+	    pmx->func_selector != func_selector) {
+		dev_err(&pctldev->dev,
+			"dual function defines in the map for device %s\n",
+		       devname);
+		return -EINVAL;
+	}
+	pmx->func_selector = func_selector;
+
+	/* Now add this group selector, we may have many of them */
+	grp = kmalloc(sizeof(struct pinmux_group), GFP_KERNEL);
+	if (!grp)
+		return -ENOMEM;
+	grp->group_selector = group_selector;
+	ret = acquire_pins(pctldev, func_selector, group_selector);
+	if (ret) {
+		kfree(grp);
+		return ret;
+	}
+	list_add(&grp->node, &pmx->groups);
+
+	return 0;
+}
+
+static void pinmux_free_groups(struct pinmux *pmx)
+{
+	struct list_head *node, *tmp;
+
+	list_for_each_safe(node, tmp, &pmx->groups) {
+		struct pinmux_group *grp =
+			list_entry(node, struct pinmux_group, node);
+		/* Release all pins taken by this group */
+		release_pins(pmx->pctldev, grp->group_selector);
+		list_del(node);
+		kfree(grp);
+	}
+}
+
+/**
+ * pinmux_get() - retrieves the pinmux for a certain device
+ * @dev: the device to get the pinmux for
+ * @name: an optional specific mux mapping name or NULL, the name is only
+ *	needed if you want to have more than one mapping per device, or if you
+ *	need an anonymous pinmux (not tied to any specific device)
+ */
+struct pinmux *pinmux_get(struct device *dev, const char *name)
+{
+
+	struct pinmux_map const *map = NULL;
+	struct pinctrl_dev *pctldev = NULL;
+	const char *devname = NULL;
+	struct pinmux *pmx;
+	bool found_map;
+	unsigned num_maps = 0;
+	int ret = -ENODEV;
+	int i;
+
+	/* We must have dev or ID or both */
+	if (!dev && !name)
+		return ERR_PTR(-EINVAL);
+
+	if (dev)
+		devname = dev_name(dev);
+
+	pr_debug("get mux %s for device %s\n", name,
+		 devname ? devname : "(none)");
+
+	/*
+	 * create the state cookie holder struct pinmux for each
+	 * mapping, this is what consumers will get when requesting
+	 * a pinmux handle with pinmux_get()
+	 */
+	pmx = kzalloc(sizeof(struct pinmux), GFP_KERNEL);
+	if (pmx == NULL)
+		return ERR_PTR(-ENOMEM);
+	mutex_init(&pmx->mutex);
+	pmx->func_selector = UINT_MAX;
+	INIT_LIST_HEAD(&pmx->groups);
+
+	/* Iterate over the pinmux maps to locate the right ones */
+	for (i = 0; i < pinmux_maps_num; i++) {
+		map = &pinmux_maps[i];
+		found_map = false;
+
+		/*
+		 * First, try to find the pctldev given in the map
+		 */
+		pctldev = get_pinctrl_dev_from_dev(map->ctrl_dev,
+						   map->ctrl_dev_name);
+		if (!pctldev) {
+			const char *devname = NULL;
+
+			if (map->ctrl_dev)
+				devname = dev_name(map->ctrl_dev);
+			else if (map->ctrl_dev_name)
+				devname = map->ctrl_dev_name;
+
+			pr_warning("could not find a pinctrl device for pinmux "
+				   "function %s, fishy, they shall all have one\n",
+				   map->function);
+			pr_warning("given pinctrl device name: %s",
+				   devname ? devname : "UNDEFINED");
+
+			/* Continue to check the other mappings anyway... */
+			continue;
+		}
+
+		pr_debug("in map, found pctldev %s to handle function %s",
+			 dev_name(&pctldev->dev), map->function);
+
+
+		/*
+		 * If we're looking for a specific named map, this must match,
+		 * else we loop and look for the next.
+		 */
+		if (name != NULL) {
+			if (map->name == NULL)
+				continue;
+			if (strcmp(map->name, name))
+				continue;
+		}
+
+		/*
+		 * This is for the case where no device name is given, we
+		 * already know that the function name matches from above
+		 * code.
+		 */
+		if (!map->dev_name && (name != NULL))
+			found_map = true;
+
+		/* If the mapping has a device set up it must match */
+		if (map->dev_name &&
+		    (!devname || !strcmp(map->dev_name, devname)))
+			/* MATCH! */
+			found_map = true;
+
+		/* If this map is applicable, then apply it */
+		if (found_map) {
+			ret = pinmux_enable_muxmap(pctldev, pmx, dev,
+						   devname, map);
+			if (ret) {
+				pinmux_free_groups(pmx);
+				kfree(pmx);
+				return ERR_PTR(ret);
+			}
+			num_maps++;
+		}
+	}
+
+
+	/* We should have atleast one map, right */
+	if (!num_maps) {
+		pr_err("could not find any mux maps for device %s, ID %s\n",
+		       devname ? devname : "(anonymous)",
+		       name ? name : "(undefined)");
+		kfree(pmx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	pr_debug("found %u mux maps for device %s, UD %s\n",
+		 num_maps,
+		 devname ? devname : "(anonymous)",
+		 name ? name : "(undefined)");
+
+	/* Add the pinmux to the global list */
+	mutex_lock(&pinmux_list_mutex);
+	list_add(&pmx->node, &pinmux_list);
+	mutex_unlock(&pinmux_list_mutex);
+
+	return pmx;
+}
+EXPORT_SYMBOL_GPL(pinmux_get);
+
+/**
+ * pinmux_put() - release a previously claimed pinmux
+ * @pmx: a pinmux previously claimed by pinmux_get()
+ */
+void pinmux_put(struct pinmux *pmx)
+{
+	if (pmx == NULL)
+		return;
+
+	mutex_lock(&pmx->mutex);
+	if (pmx->usecount)
+		pr_warn("releasing pinmux with active users!\n");
+	/* Free the groups and all acquired pins */
+	pinmux_free_groups(pmx);
+	mutex_unlock(&pmx->mutex);
+
+	/* Remove from list */
+	mutex_lock(&pinmux_list_mutex);
+	list_del(&pmx->node);
+	mutex_unlock(&pinmux_list_mutex);
+
+	kfree(pmx);
+}
+EXPORT_SYMBOL_GPL(pinmux_put);
+
+/**
+ * pinmux_enable() - enable a certain pinmux setting
+ * @pmx: the pinmux to enable, previously claimed by pinmux_get()
+ */
+int pinmux_enable(struct pinmux *pmx)
+{
+	int ret = 0;
+
+	if (pmx == NULL)
+		return -EINVAL;
+	mutex_lock(&pmx->mutex);
+	if (pmx->usecount++ == 0) {
+		struct pinctrl_dev *pctldev = pmx->pctldev;
+		const struct pinmux_ops *ops = pctldev->desc->pmxops;
+		struct pinmux_group *grp;
+
+		list_for_each_entry(grp, &pmx->groups, node) {
+			ret = ops->enable(pctldev, pmx->func_selector,
+					  grp->group_selector);
+			if (ret) {
+				/*
+				 * TODO: call disable() on all groups we called
+				 * enable() on to this point?
+				 */
+				pmx->usecount--;
+				break;
+			}
+		}
+	}
+	mutex_unlock(&pmx->mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pinmux_enable);
+
+/**
+ * pinmux_disable() - disable a certain pinmux setting
+ * @pmx: the pinmux to disable, previously claimed by pinmux_get()
+ */
+void pinmux_disable(struct pinmux *pmx)
+{
+	if (pmx == NULL)
+		return;
+
+	mutex_lock(&pmx->mutex);
+	if (--pmx->usecount == 0) {
+		struct pinctrl_dev *pctldev = pmx->pctldev;
+		const struct pinmux_ops *ops = pctldev->desc->pmxops;
+		struct pinmux_group *grp;
+
+		list_for_each_entry(grp, &pmx->groups, node) {
+			ops->disable(pctldev, pmx->func_selector,
+				     grp->group_selector);
+		}
+	}
+	mutex_unlock(&pmx->mutex);
+}
+EXPORT_SYMBOL_GPL(pinmux_disable);
+
+int pinmux_check_ops(const struct pinmux_ops *ops)
+{
+	/* Check that we implement required operations */
+	if (!ops->list_functions ||
+	    !ops->get_function_name ||
+	    !ops->get_function_groups ||
+	    !ops->enable ||
+	    !ops->disable)
+		return -EINVAL;
+
+	return 0;
+}
+
+/* Hog a single map entry and add to the hoglist */
+static int pinmux_hog_map(struct pinctrl_dev *pctldev,
+			  struct pinmux_map const *map)
+{
+	struct pinmux_hog *hog;
+	struct pinmux *pmx;
+	int ret;
+
+	if (map->dev || map->dev_name) {
+		/*
+		 * TODO: the day we have device tree support, we can
+		 * traverse the device tree and hog to specific device nodes
+		 * without any problems, so then we can hog pinmuxes for
+		 * all devices that just want a static pin mux at this point.
+		 */
+		dev_err(&pctldev->dev, "map %s wants to hog a non-system "
+			"pinmux, this is not going to work\n", map->name);
+		return -EINVAL;
+	}
+
+	hog = kzalloc(sizeof(struct pinmux_hog), GFP_KERNEL);
+	if (!hog)
+		return -ENOMEM;
+
+	pmx = pinmux_get(NULL, map->name);
+	if (IS_ERR(pmx)) {
+		kfree(hog);
+		dev_err(&pctldev->dev,
+			"could not get the %s pinmux mapping for hogging\n",
+			map->name);
+		return PTR_ERR(pmx);
+	}
+
+	ret = pinmux_enable(pmx);
+	if (ret) {
+		pinmux_put(pmx);
+		kfree(hog);
+		dev_err(&pctldev->dev,
+			"could not enable the %s pinmux mapping for hogging\n",
+			map->name);
+		return ret;
+	}
+
+	hog->map = map;
+	hog->pmx = pmx;
+
+	dev_info(&pctldev->dev, "hogged map %s, function %s\n", map->name,
+		 map->function);
+	mutex_lock(&pctldev->pinmux_hogs_lock);
+	list_add(&hog->node, &pctldev->pinmux_hogs);
+	mutex_unlock(&pctldev->pinmux_hogs_lock);
+
+	return 0;
+}
+
+/**
+ * pinmux_hog_maps() - hog specific map entries on controller device
+ * @pctldev: the pin control device to hog entries on
+ *
+ * When the pin controllers are registered, there may be some specific pinmux
+ * map entries that need to be hogged, i.e. get+enabled until the system shuts
+ * down.
+ */
+int pinmux_hog_maps(struct pinctrl_dev *pctldev)
+{
+	struct device *dev = &pctldev->dev;
+	const char *devname = dev_name(dev);
+	int ret;
+	int i;
+
+	INIT_LIST_HEAD(&pctldev->pinmux_hogs);
+	mutex_init(&pctldev->pinmux_hogs_lock);
+
+	for (i = 0; i < pinmux_maps_num; i++) {
+		struct pinmux_map const *map = &pinmux_maps[i];
+
+		if (((map->ctrl_dev == dev) ||
+		     !strcmp(map->ctrl_dev_name, devname)) &&
+		    map->hog_on_boot) {
+			/* OK time to hog! */
+			ret = pinmux_hog_map(pctldev, map);
+			if (ret)
+				return ret;
+		}
+	}
+	return 0;
+}
+
+/**
+ * pinmux_hog_maps() - unhog specific map entries on controller device
+ * @pctldev: the pin control device to unhog entries on
+ */
+void pinmux_unhog_maps(struct pinctrl_dev *pctldev)
+{
+	struct list_head *node, *tmp;
+
+	mutex_lock(&pctldev->pinmux_hogs_lock);
+	list_for_each_safe(node, tmp, &pctldev->pinmux_hogs) {
+		struct pinmux_hog *hog =
+			list_entry(node, struct pinmux_hog, node);
+		pinmux_disable(hog->pmx);
+		pinmux_put(hog->pmx);
+		list_del(node);
+		kfree(hog);
+	}
+	mutex_unlock(&pctldev->pinmux_hogs_lock);
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+/* Called from pincontrol core */
+static int pinmux_functions_show(struct seq_file *s, void *what)
+{
+	struct pinctrl_dev *pctldev = s->private;
+	const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
+	unsigned func_selector = 0;
+
+	while (pmxops->list_functions(pctldev, func_selector) >= 0) {
+		const char *func = pmxops->get_function_name(pctldev,
+							  func_selector);
+		const char * const *groups;
+		unsigned num_groups;
+		int ret;
+		int i;
+
+		ret = pmxops->get_function_groups(pctldev, func_selector,
+						  &groups, &num_groups);
+		if (ret)
+			seq_printf(s, "function %s: COULD NOT GET GROUPS\n",
+				   func);
+
+		seq_printf(s, "function: %s, groups = [ ", func);
+		for (i = 0; i < num_groups; i++)
+			seq_printf(s, "%s ", groups[i]);
+		seq_puts(s, "]\n");
+
+		func_selector++;
+
+	}
+
+	return 0;
+}
+
+static int pinmux_pins_show(struct seq_file *s, void *what)
+{
+	struct pinctrl_dev *pctldev = s->private;
+	unsigned pin;
+
+	seq_puts(s, "Pinmux settings per pin\n");
+	seq_puts(s, "Format: pin (name): pinmuxfunction\n");
+
+	/* The highest pin number need to be included in the loop, thus <= */
+	for (pin = 0; pin <= pctldev->desc->maxpin; pin++) {
+
+		struct pin_desc *desc;
+
+		desc = pin_desc_get(pctldev, pin);
+		/* Pin space may be sparse */
+		if (desc == NULL)
+			continue;
+
+		seq_printf(s, "pin %d (%s): %s\n", pin,
+			   desc->name ? desc->name : "unnamed",
+			   desc->mux_requested ? desc->mux_function : "UNCLAIMED");
+	}
+
+	return 0;
+}
+
+static int pinmux_hogs_show(struct seq_file *s, void *what)
+{
+	struct pinctrl_dev *pctldev = s->private;
+	struct pinmux_hog *hog;
+
+	seq_puts(s, "Pinmux map hogs held by device\n");
+
+	list_for_each_entry(hog, &pctldev->pinmux_hogs, node)
+		seq_printf(s, "%s\n", hog->map->name);
+
+	return 0;
+}
+
+static int pinmux_show(struct seq_file *s, void *what)
+{
+	struct pinmux *pmx;
+
+	seq_puts(s, "Requested pinmuxes and their maps:\n");
+	list_for_each_entry(pmx, &pinmux_list, node) {
+		struct pinctrl_dev *pctldev = pmx->pctldev;
+		const struct pinmux_ops *pmxops;
+		const struct pinctrl_ops *pctlops;
+		struct pinmux_group *grp;
+
+		if (!pctldev) {
+			seq_puts(s, "NO PIN CONTROLLER DEVICE\n");
+			continue;
+		}
+
+		pmxops = pctldev->desc->pmxops;
+		pctlops = pctldev->desc->pctlops;
+
+		seq_printf(s, "device: %s function: %s (%u),",
+			   pinctrl_dev_get_name(pmx->pctldev),
+			   pmxops->get_function_name(pctldev, pmx->func_selector),
+			   pmx->func_selector);
+
+		seq_printf(s, " groups: [");
+		list_for_each_entry(grp, &pmx->groups, node) {
+			seq_printf(s, " %s (%u)",
+				   pctlops->get_group_name(pctldev, grp->group_selector),
+				   grp->group_selector);
+		}
+		seq_printf(s, " ]");
+
+		seq_printf(s, " users: %u map-> %s\n",
+			   pmx->usecount,
+			   pmx->dev ? dev_name(pmx->dev) : "(system)");
+	}
+
+	return 0;
+}
+
+static int pinmux_maps_show(struct seq_file *s, void *what)
+{
+	int i;
+
+	seq_puts(s, "Pinmux maps:\n");
+
+	for (i = 0; i < pinmux_maps_num; i++) {
+		struct pinmux_map const *map = &pinmux_maps[i];
+
+		seq_printf(s, "%s:\n", map->name);
+		if (map->dev || map->dev_name)
+			seq_printf(s, "  device: %s\n",
+				   map->dev ? dev_name(map->dev) :
+				   map->dev_name);
+		else
+			seq_printf(s, "  SYSTEM MUX\n");
+		seq_printf(s, "  controlling device %s\n",
+			   map->ctrl_dev ? dev_name(map->ctrl_dev) :
+			   map->ctrl_dev_name);
+		seq_printf(s, "  function: %s\n", map->function);
+		seq_printf(s, "  group: %s\n", map->group ? map->group :
+			   "(default)");
+	}
+	return 0;
+}
+
+static int pinmux_functions_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pinmux_functions_show, inode->i_private);
+}
+
+static int pinmux_pins_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pinmux_pins_show, inode->i_private);
+}
+
+static int pinmux_hogs_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pinmux_hogs_show, inode->i_private);
+}
+
+static int pinmux_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pinmux_show, NULL);
+}
+
+static int pinmux_maps_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pinmux_maps_show, NULL);
+}
+
+static const struct file_operations pinmux_functions_ops = {
+	.open		= pinmux_functions_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static const struct file_operations pinmux_pins_ops = {
+	.open		= pinmux_pins_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static const struct file_operations pinmux_hogs_ops = {
+	.open		= pinmux_hogs_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static const struct file_operations pinmux_ops = {
+	.open		= pinmux_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static const struct file_operations pinmux_maps_ops = {
+	.open		= pinmux_maps_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+void pinmux_init_device_debugfs(struct dentry *devroot,
+			 struct pinctrl_dev *pctldev)
+{
+	debugfs_create_file("pinmux-functions", S_IFREG | S_IRUGO,
+			    devroot, pctldev, &pinmux_functions_ops);
+	debugfs_create_file("pinmux-pins", S_IFREG | S_IRUGO,
+			    devroot, pctldev, &pinmux_pins_ops);
+	debugfs_create_file("pinmux-hogs", S_IFREG | S_IRUGO,
+			    devroot, pctldev, &pinmux_hogs_ops);
+}
+
+void pinmux_init_debugfs(struct dentry *subsys_root)
+{
+	debugfs_create_file("pinmuxes", S_IFREG | S_IRUGO,
+			    subsys_root, NULL, &pinmux_ops);
+	debugfs_create_file("pinmux-maps", S_IFREG | S_IRUGO,
+			    subsys_root, NULL, &pinmux_maps_ops);
+}
+
+#endif /* CONFIG_DEBUG_FS */