/*
 * drivers/clk/clkdev.c
 *
 *  Copyright (C) 2008 Russell King.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Helper for the clk API to assist looking up a struct clk.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/mutex.h>
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/clk-provider.h>
#include <linux/of.h>

#include "clk.h"

static LIST_HEAD(clocks);
static DEFINE_MUTEX(clocks_mutex);

#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
static struct clk *__of_clk_get(struct device_node *np, int index,
                               const char *dev_id, const char *con_id)
{
        struct of_phandle_args clkspec;
        struct clk *clk;
        int rc;

        if (index < 0)
                return ERR_PTR(-EINVAL);

        rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
                                        &clkspec);
        if (rc)
                return ERR_PTR(rc);

        clk = __of_clk_get_from_provider(&clkspec, dev_id, con_id);
        of_node_put(clkspec.np);

        return clk;
}

struct clk *of_clk_get(struct device_node *np, int index)
{
        return __of_clk_get(np, index, np->full_name, NULL);
}
EXPORT_SYMBOL(of_clk_get);

static struct clk *__of_clk_get_by_name(struct device_node *np,
                                        const char *dev_id,
                                        const char *name)
{
        struct clk *clk = ERR_PTR(-ENOENT);

        /* Walk up the tree of devices looking for a clock that matches */
        while (np) {
                int index = 0;

                /*
                 * For named clocks, first look up the name in the
                 * "clock-names" property.  If it cannot be found, then
                 * index will be an error code, and of_clk_get() will fail.
                 */
                if (name)
                        index = of_property_match_string(np, "clock-names", name);
                clk = __of_clk_get(np, index, dev_id, name);
                if (!IS_ERR(clk)) {
                        break;
                } else if (name && index >= 0) {
                        if (PTR_ERR(clk) != -EPROBE_DEFER)
                                pr_err("ERROR: could not get clock %s:%s(%i)\n",
                                        np->full_name, name ? name : "", index);
                        return clk;
                }

                /*
                 * No matching clock found on this node.  If the parent node
                 * has a "clock-ranges" property, then we can try one of its
                 * clocks.
                 */
                np = np->parent;
                if (np && !of_get_property(np, "clock-ranges", NULL))
                        break;
        }

        return clk;
}

/**
 * of_clk_get_by_name() - Parse and lookup a clock referenced by a device node
 * @np: pointer to clock consumer node
 * @name: name of consumer's clock input, or NULL for the first clock reference
 *
 * This function parses the clocks and clock-names properties,
 * and uses them to look up the struct clk from the registered list of clock
 * providers.
 */
struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
{
        if (!np)
                return ERR_PTR(-ENOENT);

        return __of_clk_get_by_name(np, np->full_name, name);
}
EXPORT_SYMBOL(of_clk_get_by_name);

#else /* defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) */

static struct clk *__of_clk_get_by_name(struct device_node *np,
                                        const char *dev_id,
                                        const char *name)
{
        return ERR_PTR(-ENOENT);
}
#endif

/*
 * Find the correct struct clk for the device and connection ID.
 * We do slightly fuzzy matching here:
 *  An entry with a NULL ID is assumed to be a wildcard.
 *  If an entry has a device ID, it must match
 *  If an entry has a connection ID, it must match
 * Then we take the most specific entry - with the following
 * order of precedence: dev+con > dev only > con only.
 */
static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
{
        struct clk_lookup *p, *cl = NULL;
        int match, best_found = 0, best_possible = 0;

        if (dev_id)
                best_possible += 2;
        if (con_id)
                best_possible += 1;

        list_for_each_entry(p, &clocks, node) {
                match = 0;
                if (p->dev_id) {
                        if (!dev_id || strcmp(p->dev_id, dev_id))
                                continue;
                        match += 2;
                }
                if (p->con_id) {
                        if (!con_id || strcmp(p->con_id, con_id))
                                continue;
                        match += 1;
                }

                if (match > best_found) {
                        cl = p;
                        if (match != best_possible)
                                best_found = match;
                        else
                                break;
                }
        }
        return cl;
}

struct clk *clk_get_sys(const char *dev_id, const char *con_id)
{
        struct clk_lookup *cl;
        struct clk *clk = NULL;

        mutex_lock(&clocks_mutex);

        cl = clk_find(dev_id, con_id);
        if (!cl)
                goto out;

        clk = __clk_create_clk(cl->clk_hw, dev_id, con_id);
        if (IS_ERR(clk))
                goto out;

        if (!__clk_get(clk)) {
                __clk_free_clk(clk);
                cl = NULL;
                goto out;
        }

out:
        mutex_unlock(&clocks_mutex);

        return cl ? clk : ERR_PTR(-ENOENT);
}
EXPORT_SYMBOL(clk_get_sys);

struct clk *clk_get(struct device *dev, const char *con_id)
{
        const char *dev_id = dev ? dev_name(dev) : NULL;
        struct clk *clk;

        if (dev) {
                clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id);
                if (!IS_ERR(clk) || PTR_ERR(clk) == -EPROBE_DEFER)
                        return clk;
        }

        return clk_get_sys(dev_id, con_id);
}
EXPORT_SYMBOL(clk_get);

void clk_put(struct clk *clk)
{
        __clk_put(clk);
}
EXPORT_SYMBOL(clk_put);

static void __clkdev_add(struct clk_lookup *cl)
{
        mutex_lock(&clocks_mutex);
        list_add_tail(&cl->node, &clocks);
        mutex_unlock(&clocks_mutex);
}

void clkdev_add(struct clk_lookup *cl)
{
        if (!cl->clk_hw)
                cl->clk_hw = __clk_get_hw(cl->clk);
        __clkdev_add(cl);
}
EXPORT_SYMBOL(clkdev_add);

void clkdev_add_table(struct clk_lookup *cl, size_t num)
{
        mutex_lock(&clocks_mutex);
        while (num--) {
                cl->clk_hw = __clk_get_hw(cl->clk);
                list_add_tail(&cl->node, &clocks);
                cl++;
        }
        mutex_unlock(&clocks_mutex);
}

#define MAX_DEV_ID      20
#define MAX_CON_ID      16

struct clk_lookup_alloc {
        struct clk_lookup cl;
        char    dev_id[MAX_DEV_ID];
        char    con_id[MAX_CON_ID];
};

static struct clk_lookup * __init_refok
vclkdev_alloc(struct clk_hw *hw, const char *con_id, const char *dev_fmt,
        va_list ap)
{
        struct clk_lookup_alloc *cla;

        cla = __clkdev_alloc(sizeof(*cla));
        if (!cla)
                return NULL;

        cla->cl.clk_hw = hw;
        if (con_id) {
                strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
                cla->cl.con_id = cla->con_id;
        }

        if (dev_fmt) {
                vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
                cla->cl.dev_id = cla->dev_id;
        }

        return &cla->cl;
}

static struct clk_lookup *
vclkdev_create(struct clk_hw *hw, const char *con_id, const char *dev_fmt,
        va_list ap)
{
        struct clk_lookup *cl;

        cl = vclkdev_alloc(hw, con_id, dev_fmt, ap);
        if (cl)
                __clkdev_add(cl);

        return cl;
}

struct clk_lookup * __init_refok
clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
{
        struct clk_lookup *cl;
        va_list ap;

        va_start(ap, dev_fmt);
        cl = vclkdev_alloc(__clk_get_hw(clk), con_id, dev_fmt, ap);
        va_end(ap);

        return cl;
}
EXPORT_SYMBOL(clkdev_alloc);

/**
 * clkdev_create - allocate and add a clkdev lookup structure
 * @clk: struct clk to associate with all clk_lookups
 * @con_id: connection ID string on device
 * @dev_fmt: format string describing device name
 *
 * Returns a clk_lookup structure, which can be later unregistered and
 * freed.
 */
struct clk_lookup *clkdev_create(struct clk *clk, const char *con_id,
        const char *dev_fmt, ...)
{
        struct clk_lookup *cl;
        va_list ap;

        va_start(ap, dev_fmt);
        cl = vclkdev_create(__clk_get_hw(clk), con_id, dev_fmt, ap);
        va_end(ap);

        return cl;
}
EXPORT_SYMBOL_GPL(clkdev_create);

int clk_add_alias(const char *alias, const char *alias_dev_name,
        const char *con_id, struct device *dev)
{
        struct clk *r = clk_get(dev, con_id);
        struct clk_lookup *l;

        if (IS_ERR(r))
                return PTR_ERR(r);

        l = clkdev_create(r, alias, alias_dev_name ? "%s" : NULL,
                          alias_dev_name);
        clk_put(r);

        return l ? 0 : -ENODEV;
}
EXPORT_SYMBOL(clk_add_alias);

/*
 * clkdev_drop - remove a clock dynamically allocated
 */
void clkdev_drop(struct clk_lookup *cl)
{
        mutex_lock(&clocks_mutex);
        list_del(&cl->node);
        mutex_unlock(&clocks_mutex);
        kfree(cl);
}
EXPORT_SYMBOL(clkdev_drop);

/**
 * clk_register_clkdev - register one clock lookup for a struct clk
 * @clk: struct clk to associate with all clk_lookups
 * @con_id: connection ID string on device
 * @dev_id: format string describing device name
 *
 * con_id or dev_id may be NULL as a wildcard, just as in the rest of
 * clkdev.
 *
 * To make things easier for mass registration, we detect error clks
 * from a previous clk_register() call, and return the error code for
 * those.  This is to permit this function to be called immediately
 * after clk_register().
 */
int clk_register_clkdev(struct clk *clk, const char *con_id,
        const char *dev_fmt, ...)
{
        struct clk_lookup *cl;
        va_list ap;

        if (IS_ERR(clk))
                return PTR_ERR(clk);

        va_start(ap, dev_fmt);
        cl = vclkdev_create(__clk_get_hw(clk), con_id, dev_fmt, ap);
        va_end(ap);

        return cl ? 0 : -ENOMEM;
}
EXPORT_SYMBOL(clk_register_clkdev);

/**
 * clk_register_clkdevs - register a set of clk_lookup for a struct clk
 * @clk: struct clk to associate with all clk_lookups
 * @cl: array of clk_lookup structures with con_id and dev_id pre-initialized
 * @num: number of clk_lookup structures to register
 *
 * To make things easier for mass registration, we detect error clks
 * from a previous clk_register() call, and return the error code for
 * those.  This is to permit this function to be called immediately
 * after clk_register().
 */
int clk_register_clkdevs(struct clk *clk, struct clk_lookup *cl, size_t num)
{
        unsigned i;

        if (IS_ERR(clk))
                return PTR_ERR(clk);

        for (i = 0; i < num; i++, cl++) {
                cl->clk_hw = __clk_get_hw(clk);
                __clkdev_add(cl);
        }

        return 0;
}
EXPORT_SYMBOL(clk_register_clkdevs);