Linux 3.3-rc6

[linux/fpc-iii.git] / drivers / pinctrl / pinmux.c

/*
 * 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/string.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);

/* Global pinmux maps */
static struct pinmux_map *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
 * @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_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,
                       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);

        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;
        }

        if (!function) {
                dev_err(pctldev->dev, "no function name given\n");
                return -EINVAL;
        }

        spin_lock(&desc->lock);
        if (desc->mux_function) {
                spin_unlock(&desc->lock);
                dev_err(pctldev->dev,
                        "pin already requested\n");
                goto out;
        }
        desc->mux_function = 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_range && 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_function = NULL;
                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
 * @gpio_range: the range matching the GPIO pin if this is a request for a
 *      single GPIO pin
 *
 * This function returns a pointer to the function name in use. This is used
 * for callers that dynamically allocate a function name so it can be freed
 * once the pin is free. This is done for GPIO request functions.
 */
static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
                            struct pinctrl_gpio_range *gpio_range)
{
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        struct pin_desc *desc;
        const char *func;

        desc = pin_desc_get(pctldev, pin);
        if (desc == NULL) {
                dev_err(pctldev->dev,
                        "pin is not registered so it cannot be freed\n");
                return NULL;
        }

        /*
         * If there is no kind of request function for the pin we just assume
         * we got it by default and proceed.
         */
        if (gpio_range && ops->gpio_disable_free)
                ops->gpio_disable_free(pctldev, gpio_range, pin);
        else if (ops->free)
                ops->free(pctldev, pin);

        spin_lock(&desc->lock);
        func = desc->mux_function;
        desc->mux_function = NULL;
        spin_unlock(&desc->lock);
        module_put(pctldev->owner);

        return func;
}

/**
 * pinmux_request_gpio() - request a single pin to be muxed in as GPIO
 * @gpio: the GPIO pin number from the GPIO subsystem number space
 *
 * This function should *ONLY* be used from gpiolib-based GPIO drivers,
 * as part of their gpio_request() semantics, platforms and individual drivers
 * shall *NOT* request GPIO pins to be muxed in.
 */
int pinmux_request_gpio(unsigned gpio)
{
        char gpiostr[16];
        const char *function;
        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 + range->pin_base;

        /* Conjure some name stating what chip and pin this is taken by */
        snprintf(gpiostr, 15, "%s:%d", range->name, gpio);

        function = kstrdup(gpiostr, GFP_KERNEL);
        if (!function)
                return -EINVAL;

        ret = pin_request(pctldev, pin, function, range);
        if (ret < 0)
                kfree(function);

        return ret;
}
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
 *
 * This function should *ONLY* be used from gpiolib-based GPIO drivers,
 * as part of their gpio_free() semantics, platforms and individual drivers
 * shall *NOT* request GPIO pins to be muxed out.
 */
void pinmux_free_gpio(unsigned gpio)
{
        struct pinctrl_dev *pctldev;
        struct pinctrl_gpio_range *range;
        int ret;
        int pin;
        const char *func;

        ret = pinctrl_get_device_gpio_range(gpio, &pctldev, &range);
        if (ret)
                return;

        /* Convert to the pin controllers number space */
        pin = gpio - range->base + range->pin_base;

        func = pin_free(pctldev, pin, range);
        kfree(func);
}
EXPORT_SYMBOL_GPL(pinmux_free_gpio);

static int pinmux_gpio_direction(unsigned gpio, bool input)
{
        struct pinctrl_dev *pctldev;
        struct pinctrl_gpio_range *range;
        const struct pinmux_ops *ops;
        int ret;
        int pin;

        ret = pinctrl_get_device_gpio_range(gpio, &pctldev, &range);
        if (ret)
                return ret;

        ops = pctldev->desc->pmxops;

        /* Convert to the pin controllers number space */
        pin = gpio - range->base + range->pin_base;

        if (ops->gpio_set_direction)
                ret = ops->gpio_set_direction(pctldev, range, pin, input);
        else
                ret = 0;

        return ret;
}

/**
 * pinmux_gpio_direction_input() - request a GPIO pin to go into input mode
 * @gpio: the GPIO pin number from the GPIO subsystem number space
 *
 * This function should *ONLY* be used from gpiolib-based GPIO drivers,
 * as part of their gpio_direction_input() semantics, platforms and individual
 * drivers shall *NOT* touch pinmux GPIO calls.
 */
int pinmux_gpio_direction_input(unsigned gpio)
{
        return pinmux_gpio_direction(gpio, true);
}
EXPORT_SYMBOL_GPL(pinmux_gpio_direction_input);

/**
 * pinmux_gpio_direction_output() - request a GPIO pin to go into output mode
 * @gpio: the GPIO pin number from the GPIO subsystem number space
 *
 * This function should *ONLY* be used from gpiolib-based GPIO drivers,
 * as part of their gpio_direction_output() semantics, platforms and individual
 * drivers shall *NOT* touch pinmux GPIO calls.
 */
int pinmux_gpio_direction_output(unsigned gpio)
{
        return pinmux_gpio_direction(gpio, false);
}
EXPORT_SYMBOL_GPL(pinmux_gpio_direction_output);

/**
 * pinmux_register_mappings() - register a set of pinmux mappings
 * @maps: the pinmux mappings table to register, this should be marked with
 *      __initdata so it can be discarded after boot, this function will
 *      perform a shallow copy for the mapping entries.
 * @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
 * freed.
 */
int __init pinmux_register_mappings(struct pinmux_map const *maps,
                                    unsigned num_maps)
{
        void *tmp_maps;
        int i;

        pr_debug("add %d pinmux maps\n", num_maps);

        /* First sanity check the new mapping */
        for (i = 0; i < num_maps; i++) {
                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);
        }

        /*
         * Make a copy of the map array - string pointers will end up in the
         * kernel const section anyway so these do not need to be deep copied.
         */
        if (!pinmux_maps_num) {
                /* On first call, just copy them */
                tmp_maps = kmemdup(maps,
                                   sizeof(struct pinmux_map) * num_maps,
                                   GFP_KERNEL);
                if (!tmp_maps)
                        return -ENOMEM;
        } else {
                /* Subsequent calls, reallocate array to new size */
                size_t oldsize = sizeof(struct pinmux_map) * pinmux_maps_num;
                size_t newsize = sizeof(struct pinmux_map) * num_maps;

                tmp_maps = krealloc(pinmux_maps, oldsize + newsize, GFP_KERNEL);
                if (!tmp_maps)
                        return -ENOMEM;
                memcpy((tmp_maps + oldsize), maps, newsize);
        }

        pinmux_maps = tmp_maps;
        pinmux_maps_num += num_maps;
        return 0;
}

/**
 * acquire_pins() - acquire all the pins for a certain function 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);
        const 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, 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], NULL);
                        return -ENODEV;
                }
        }
        return 0;
}

/**
 * release_pins() - release pins taken by earlier acquirement
 * @pctldev: the device to free the pins 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;
        const 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], NULL);
}

/**
 * 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 = pinctrl_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 = pinctrl_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(struct pinctrl_dev *pctldev)
{
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        unsigned selector = 0;

        /* Check that we implement required operations */
        if (!ops->list_functions ||
            !ops->get_function_name ||
            !ops->get_function_groups ||
            !ops->enable ||
            !ops->disable)
                return -EINVAL;

        /* Check that all functions registered have names */
        while (ops->list_functions(pctldev, selector) >= 0) {
                const char *fname = ops->get_function_name(pctldev,
                                                           selector);
                if (!fname) {
                        pr_err("pinmux ops has no name for function%u\n",
                                selector);
                        return -EINVAL;
                }
                selector++;
        }

        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->hog_on_boot)
                        continue;

                if ((map->ctrl_dev == dev) ||
                        (map->ctrl_dev_name &&
                                !strcmp(map->ctrl_dev_name, devname))) {
                        /* OK time to hog! */
                        ret = pinmux_hog_map(pctldev, map);
                        if (ret)
                                return ret;
                }
        }
        return 0;
}

/**
 * pinmux_unhog_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 i, pin;

        seq_puts(s, "Pinmux settings per pin\n");
        seq_puts(s, "Format: pin (name): pinmuxfunction\n");

        /* The pin number can be retrived from the pin controller descriptor */
        for (i = 0; i < pctldev->desc->npins; i++) {

                struct pin_desc *desc;

                pin = pctldev->desc->pins[i].number;
                desc = pin_desc_get(pctldev, pin);
                /* Skip if we cannot search the pin */
                if (desc == NULL)
                        continue;

                seq_printf(s, "pin %d (%s): %s\n", pin,
                           desc->name ? desc->name : "unnamed",
                           desc->mux_function ? 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 */