/*
 * Core driver for the pin muxing portions of the pin control subsystem
 *
 * Copyright (C) 2011-2012 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>
 *
 * Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
 *
 * 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/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"
#include "pinmux.h"

int pinmux_check_ops(struct pinctrl_dev *pctldev)
{
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        unsigned nfuncs;
        unsigned selector = 0;

        /* Check that we implement required operations */
        if (!ops ||
            !ops->get_functions_count ||
            !ops->get_function_name ||
            !ops->get_function_groups ||
            !ops->enable) {
                dev_err(pctldev->dev, "pinmux ops lacks necessary functions\n");
                return -EINVAL;
        }
        /* Check that all functions registered have names */
        nfuncs = ops->get_functions_count(pctldev);
        while (selector < nfuncs) {
                const char *fname = ops->get_function_name(pctldev,
                                                           selector);
                if (!fname) {
                        dev_err(pctldev->dev, "pinmux ops has no name for function%u\n",
                                selector);
                        return -EINVAL;
                }
                selector++;
        }

        return 0;
}

int pinmux_validate_map(struct pinctrl_map const *map, int i)
{
        if (!map->data.mux.function) {
                pr_err("failed to register map %s (%d): no function given\n",
                       map->name, i);
                return -EINVAL;
        }

        return 0;
}

/**
 * pin_request() - request a single pin to be muxed in, typically for GPIO
 * @pin: the pin number in the global pin space
 * @owner: a representation of the owner of this pin; typically the device
 *      name that controls its mux function, or the requested GPIO name
 * @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 *owner,
                       struct pinctrl_gpio_range *gpio_range)
{
        struct pin_desc *desc;
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        int status = -EINVAL;

        desc = pin_desc_get(pctldev, pin);
        if (desc == NULL) {
                dev_err(pctldev->dev,
                        "pin %d is not registered so it cannot be requested\n",
                        pin);
                goto out;
        }

        dev_dbg(pctldev->dev, "request pin %d (%s) for %s\n",
                pin, desc->name, owner);

        if (gpio_range) {
                /* There's no need to support multiple GPIO requests */
                if (desc->gpio_owner) {
                        dev_err(pctldev->dev,
                                "pin %s already requested by %s; cannot claim for %s\n",
                                desc->name, desc->gpio_owner, owner);
                        goto out;
                }

                desc->gpio_owner = owner;
        } else {
                if (desc->mux_usecount && strcmp(desc->mux_owner, owner)) {
                        dev_err(pctldev->dev,
                                "pin %s already requested by %s; cannot claim for %s\n",
                                desc->name, desc->mux_owner, owner);
                        goto out;
                }

                desc->mux_usecount++;
                if (desc->mux_usecount > 1)
                        return 0;

                desc->mux_owner = owner;
        }

        /* 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() failed for pin %d\n", pin);
                module_put(pctldev->owner);
        }

out_free_pin:
        if (status) {
                if (gpio_range) {
                        desc->gpio_owner = NULL;
                } else {
                        desc->mux_usecount--;
                        if (!desc->mux_usecount)
                                desc->mux_owner = NULL;
                }
        }
out:
        if (status)
                dev_err(pctldev->dev, "pin-%d (%s) status %d\n",
                        pin, owner, 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 previous owner. This is used
 * for callers that dynamically allocate an owner 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 *owner;

        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 (!gpio_range) {
                /*
                 * A pin should not be freed more times than allocated.
                 */
                if (WARN_ON(!desc->mux_usecount))
                        return NULL;
                desc->mux_usecount--;
                if (desc->mux_usecount)
                        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);

        if (gpio_range) {
                owner = desc->gpio_owner;
                desc->gpio_owner = NULL;
        } else {
                owner = desc->mux_owner;
                desc->mux_owner = NULL;
                desc->mux_setting = NULL;
        }

        module_put(pctldev->owner);

        return owner;
}

/**
 * pinmux_request_gpio() - request pinmuxing for a GPIO pin
 * @pctldev: pin controller device affected
 * @pin: the pin to mux in for GPIO
 * @range: the applicable GPIO range
 */
int pinmux_request_gpio(struct pinctrl_dev *pctldev,
                        struct pinctrl_gpio_range *range,
                        unsigned pin, unsigned gpio)
{
        const char *owner;
        int ret;

        /* Conjure some name stating what chip and pin this is taken by */
        owner = kasprintf(GFP_KERNEL, "%s:%d", range->name, gpio);
        if (!owner)
                return -EINVAL;

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

        return ret;
}

/**
 * pinmux_free_gpio() - release a pin from GPIO muxing
 * @pctldev: the pin controller device for the pin
 * @pin: the affected currently GPIO-muxed in pin
 * @range: applicable GPIO range
 */
void pinmux_free_gpio(struct pinctrl_dev *pctldev, unsigned pin,
                      struct pinctrl_gpio_range *range)
{
        const char *owner;

        owner = pin_free(pctldev, pin, range);
        kfree(owner);
}

/**
 * pinmux_gpio_direction() - set the direction of a single muxed-in GPIO pin
 * @pctldev: the pin controller handling this pin
 * @range: applicable GPIO range
 * @pin: the affected GPIO pin in this controller
 * @input: true if we set the pin as input, false for output
 */
int pinmux_gpio_direction(struct pinctrl_dev *pctldev,
                          struct pinctrl_gpio_range *range,
                          unsigned pin, bool input)
{
        const struct pinmux_ops *ops;
        int ret;

        ops = pctldev->desc->pmxops;

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

        return ret;
}

static int pinmux_func_name_to_selector(struct pinctrl_dev *pctldev,
                                        const char *function)
{
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        unsigned nfuncs = ops->get_functions_count(pctldev);
        unsigned selector = 0;

        /* See if this pctldev has this function */
        while (selector < nfuncs) {
                const char *fname = ops->get_function_name(pctldev,
                                                           selector);

                if (!strcmp(function, fname))
                        return selector;

                selector++;
        }

        pr_err("%s does not support function %s\n",
               pinctrl_dev_get_name(pctldev), function);
        return -EINVAL;
}

int pinmux_map_to_setting(struct pinctrl_map const *map,
                          struct pinctrl_setting *setting)
{
        struct pinctrl_dev *pctldev = setting->pctldev;
        const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
        char const * const *groups;
        unsigned num_groups;
        int ret;
        const char *group;
        int i;

        if (!pmxops) {
                dev_err(pctldev->dev, "does not support mux function\n");
                return -EINVAL;
        }

        ret = pinmux_func_name_to_selector(pctldev, map->data.mux.function);
        if (ret < 0) {
                dev_err(pctldev->dev, "invalid function %s in map table\n",
                        map->data.mux.function);
                return ret;
        }
        setting->data.mux.func = ret;

        ret = pmxops->get_function_groups(pctldev, setting->data.mux.func,
                                          &groups, &num_groups);
        if (ret < 0) {
                dev_err(pctldev->dev, "can't query groups for function %s\n",
                        map->data.mux.function);
                return ret;
        }
        if (!num_groups) {
                dev_err(pctldev->dev,
                        "function %s can't be selected on any group\n",
                        map->data.mux.function);
                return -EINVAL;
        }
        if (map->data.mux.group) {
                bool found = false;
                group = map->data.mux.group;
                for (i = 0; i < num_groups; i++) {
                        if (!strcmp(group, groups[i])) {
                                found = true;
                                break;
                        }
                }
                if (!found) {
                        dev_err(pctldev->dev,
                                "invalid group \"%s\" for function \"%s\"\n",
                                group, map->data.mux.function);
                        return -EINVAL;
                }
        } else {
                group = groups[0];
        }

        ret = pinctrl_get_group_selector(pctldev, group);
        if (ret < 0) {
                dev_err(pctldev->dev, "invalid group %s in map table\n",
                        map->data.mux.group);
                return ret;
        }
        setting->data.mux.group = ret;

        return 0;
}

void pinmux_free_setting(struct pinctrl_setting const *setting)
{
        /* This function is currently unused */
}

int pinmux_enable_setting(struct pinctrl_setting const *setting)
{
        struct pinctrl_dev *pctldev = setting->pctldev;
        const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        int ret;
        const unsigned *pins;
        unsigned num_pins;
        int i;
        struct pin_desc *desc;

        ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
                                      &pins, &num_pins);
        if (ret) {
                /* errors only affect debug data, so just warn */
                dev_warn(pctldev->dev,
                         "could not get pins for group selector %d\n",
                         setting->data.mux.group);
                num_pins = 0;
        }

        /* Try to allocate all pins in this group, one by one */
        for (i = 0; i < num_pins; i++) {
                ret = pin_request(pctldev, pins[i], setting->dev_name, NULL);
                if (ret) {
                        dev_err(pctldev->dev,
                                "could not request pin %d on device %s\n",
                                pins[i], pinctrl_dev_get_name(pctldev));
                        goto err_pin_request;
                }
        }

        /* Now that we have acquired the pins, encode the mux setting */
        for (i = 0; i < num_pins; i++) {
                desc = pin_desc_get(pctldev, pins[i]);
                if (desc == NULL) {
                        dev_warn(pctldev->dev,
                                 "could not get pin desc for pin %d\n",
                                 pins[i]);
                        continue;
                }
                desc->mux_setting = &(setting->data.mux);
        }

        ret = ops->enable(pctldev, setting->data.mux.func,
                          setting->data.mux.group);

        if (ret)
                goto err_enable;

        return 0;

err_enable:
        for (i = 0; i < num_pins; i++) {
                desc = pin_desc_get(pctldev, pins[i]);
                if (desc)
                        desc->mux_setting = NULL;
        }
err_pin_request:
        /* On error release all taken pins */
        while (--i >= 0)
                pin_free(pctldev, pins[i], NULL);

        return ret;
}

void pinmux_disable_setting(struct pinctrl_setting const *setting)
{
        struct pinctrl_dev *pctldev = setting->pctldev;
        const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
        const struct pinmux_ops *ops = pctldev->desc->pmxops;
        int ret;
        const unsigned *pins;
        unsigned num_pins;
        int i;
        struct pin_desc *desc;

        ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
                                      &pins, &num_pins);
        if (ret) {
                /* errors only affect debug data, so just warn */
                dev_warn(pctldev->dev,
                         "could not get pins for group selector %d\n",
                         setting->data.mux.group);
                num_pins = 0;
        }

        /* Flag the descs that no setting is active */
        for (i = 0; i < num_pins; i++) {
                desc = pin_desc_get(pctldev, pins[i]);
                if (desc == NULL) {
                        dev_warn(pctldev->dev,
                                 "could not get pin desc for pin %d\n",
                                 pins[i]);
                        continue;
                }
                desc->mux_setting = NULL;
        }

        /* And release the pins */
        for (i = 0; i < num_pins; i++)
                pin_free(pctldev, pins[i], NULL);

        if (ops->disable)
                ops->disable(pctldev, setting->data.mux.func, setting->data.mux.group);
}

#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 nfuncs;
        unsigned func_selector = 0;

        if (!pmxops)
                return 0;

        mutex_lock(&pctldev->mutex);
        nfuncs = pmxops->get_functions_count(pctldev);
        while (func_selector < nfuncs) {
                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++;
        }

        mutex_unlock(&pctldev->mutex);

        return 0;
}

static int pinmux_pins_show(struct seq_file *s, void *what)
{
        struct pinctrl_dev *pctldev = s->private;
        const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
        const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
        unsigned i, pin;

        if (!pmxops)
                return 0;

        seq_puts(s, "Pinmux settings per pin\n");
        seq_puts(s, "Format: pin (name): mux_owner gpio_owner hog?\n");

        mutex_lock(&pctldev->mutex);

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

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

                if (desc->mux_owner &&
                    !strcmp(desc->mux_owner, pinctrl_dev_get_name(pctldev)))
                        is_hog = true;

                seq_printf(s, "pin %d (%s): %s %s%s", pin,
                           desc->name ? desc->name : "unnamed",
                           desc->mux_owner ? desc->mux_owner
                                : "(MUX UNCLAIMED)",
                           desc->gpio_owner ? desc->gpio_owner
                                : "(GPIO UNCLAIMED)",
                           is_hog ? " (HOG)" : "");

                if (desc->mux_setting)
                        seq_printf(s, " function %s group %s\n",
                                   pmxops->get_function_name(pctldev,
                                        desc->mux_setting->func),
                                   pctlops->get_group_name(pctldev,
                                        desc->mux_setting->group));
                else
                        seq_printf(s, "\n");
        }

        mutex_unlock(&pctldev->mutex);

        return 0;
}

void pinmux_show_map(struct seq_file *s, struct pinctrl_map const *map)
{
        seq_printf(s, "group %s\nfunction %s\n",
                map->data.mux.group ? map->data.mux.group : "(default)",
                map->data.mux.function);
}

void pinmux_show_setting(struct seq_file *s,
                         struct pinctrl_setting const *setting)
{
        struct pinctrl_dev *pctldev = setting->pctldev;
        const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
        const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;

        seq_printf(s, "group: %s (%u) function: %s (%u)\n",
                   pctlops->get_group_name(pctldev, setting->data.mux.group),
                   setting->data.mux.group,
                   pmxops->get_function_name(pctldev, setting->data.mux.func),
                   setting->data.mux.func);
}

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 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,
};

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);
}

#endif /* CONFIG_DEBUG_FS */