/*
 * TI composite clock support
 *
 * Copyright (C) 2013 Texas Instruments, Inc.
 *
 * Tero Kristo <t-kristo@ti.com>
 *
 * 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.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/clk/ti.h>
#include <linux/list.h>

#include "clock.h"

#undef pr_fmt
#define pr_fmt(fmt) "%s: " fmt, __func__

static unsigned long ti_composite_recalc_rate(struct clk_hw *hw,
                                              unsigned long parent_rate)
{
        return ti_clk_divider_ops.recalc_rate(hw, parent_rate);
}

static long ti_composite_round_rate(struct clk_hw *hw, unsigned long rate,
                                    unsigned long *prate)
{
        return -EINVAL;
}

static int ti_composite_set_rate(struct clk_hw *hw, unsigned long rate,
                                 unsigned long parent_rate)
{
        return -EINVAL;
}

static const struct clk_ops ti_composite_divider_ops = {
        .recalc_rate    = &ti_composite_recalc_rate,
        .round_rate     = &ti_composite_round_rate,
        .set_rate       = &ti_composite_set_rate,
};

static const struct clk_ops ti_composite_gate_ops = {
        .enable         = &omap2_dflt_clk_enable,
        .disable        = &omap2_dflt_clk_disable,
        .is_enabled     = &omap2_dflt_clk_is_enabled,
};

struct component_clk {
        int num_parents;
        const char **parent_names;
        struct device_node *node;
        int type;
        struct clk_hw *hw;
        struct list_head link;
};

static const char * const component_clk_types[] __initconst = {
        "gate", "divider", "mux"
};

static LIST_HEAD(component_clks);

static struct device_node *_get_component_node(struct device_node *node, int i)
{
        int rc;
        struct of_phandle_args clkspec;

        rc = of_parse_phandle_with_args(node, "clocks", "#clock-cells", i,
                                        &clkspec);
        if (rc)
                return NULL;

        return clkspec.np;
}

static struct component_clk *_lookup_component(struct device_node *node)
{
        struct component_clk *comp;

        list_for_each_entry(comp, &component_clks, link) {
                if (comp->node == node)
                        return comp;
        }
        return NULL;
}

struct clk_hw_omap_comp {
        struct clk_hw hw;
        struct device_node *comp_nodes[CLK_COMPONENT_TYPE_MAX];
        struct component_clk *comp_clks[CLK_COMPONENT_TYPE_MAX];
};

static inline struct clk_hw *_get_hw(struct clk_hw_omap_comp *clk, int idx)
{
        if (!clk)
                return NULL;

        if (!clk->comp_clks[idx])
                return NULL;

        return clk->comp_clks[idx]->hw;
}

#define to_clk_hw_comp(_hw) container_of(_hw, struct clk_hw_omap_comp, hw)

static void __init _register_composite(void *user,
                                       struct device_node *node)
{
        struct clk_hw *hw = user;
        struct clk *clk;
        struct clk_hw_omap_comp *cclk = to_clk_hw_comp(hw);
        struct component_clk *comp;
        int num_parents = 0;
        const char **parent_names = NULL;
        int i;
        int ret;

        /* Check for presence of each component clock */
        for (i = 0; i < CLK_COMPONENT_TYPE_MAX; i++) {
                if (!cclk->comp_nodes[i])
                        continue;

                comp = _lookup_component(cclk->comp_nodes[i]);
                if (!comp) {
                        pr_debug("component %s not ready for %s, retry\n",
                                 cclk->comp_nodes[i]->name, node->name);
                        if (!ti_clk_retry_init(node, hw,
                                               _register_composite))
                                return;

                        goto cleanup;
                }
                if (cclk->comp_clks[comp->type] != NULL) {
                        pr_err("duplicate component types for %s (%s)!\n",
                               node->name, component_clk_types[comp->type]);
                        goto cleanup;
                }

                cclk->comp_clks[comp->type] = comp;

                /* Mark this node as found */
                cclk->comp_nodes[i] = NULL;
        }

        /* All components exists, proceed with registration */
        for (i = CLK_COMPONENT_TYPE_MAX - 1; i >= 0; i--) {
                comp = cclk->comp_clks[i];
                if (!comp)
                        continue;
                if (comp->num_parents) {
                        num_parents = comp->num_parents;
                        parent_names = comp->parent_names;
                        break;
                }
        }

        if (!num_parents) {
                pr_err("%s: no parents found for %s!\n", __func__, node->name);
                goto cleanup;
        }

        clk = clk_register_composite(NULL, node->name,
                                     parent_names, num_parents,
                                     _get_hw(cclk, CLK_COMPONENT_TYPE_MUX),
                                     &ti_clk_mux_ops,
                                     _get_hw(cclk, CLK_COMPONENT_TYPE_DIVIDER),
                                     &ti_composite_divider_ops,
                                     _get_hw(cclk, CLK_COMPONENT_TYPE_GATE),
                                     &ti_composite_gate_ops, 0);

        if (!IS_ERR(clk)) {
                ret = ti_clk_add_alias(NULL, clk, node->name);
                if (ret) {
                        clk_unregister(clk);
                        goto cleanup;
                }
                of_clk_add_provider(node, of_clk_src_simple_get, clk);
        }

cleanup:
        /* Free component clock list entries */
        for (i = 0; i < CLK_COMPONENT_TYPE_MAX; i++) {
                if (!cclk->comp_clks[i])
                        continue;
                list_del(&cclk->comp_clks[i]->link);
                kfree(cclk->comp_clks[i]);
        }

        kfree(cclk);
}

static void __init of_ti_composite_clk_setup(struct device_node *node)
{
        unsigned int num_clks;
        int i;
        struct clk_hw_omap_comp *cclk;

        /* Number of component clocks to be put inside this clock */
        num_clks = of_clk_get_parent_count(node);

        if (!num_clks) {
                pr_err("composite clk %s must have component(s)\n", node->name);
                return;
        }

        cclk = kzalloc(sizeof(*cclk), GFP_KERNEL);
        if (!cclk)
                return;

        /* Get device node pointers for each component clock */
        for (i = 0; i < num_clks; i++)
                cclk->comp_nodes[i] = _get_component_node(node, i);

        _register_composite(&cclk->hw, node);
}
CLK_OF_DECLARE(ti_composite_clock, "ti,composite-clock",
               of_ti_composite_clk_setup);

/**
 * ti_clk_add_component - add a component clock to the pool
 * @node: device node of the component clock
 * @hw: hardware clock definition for the component clock
 * @type: type of the component clock
 *
 * Adds a component clock to the list of available components, so that
 * it can be registered by a composite clock.
 */
int __init ti_clk_add_component(struct device_node *node, struct clk_hw *hw,
                                int type)
{
        unsigned int num_parents;
        const char **parent_names;
        struct component_clk *clk;

        num_parents = of_clk_get_parent_count(node);

        if (!num_parents) {
                pr_err("component-clock %s must have parent(s)\n", node->name);
                return -EINVAL;
        }

        parent_names = kzalloc((sizeof(char *) * num_parents), GFP_KERNEL);
        if (!parent_names)
                return -ENOMEM;

        of_clk_parent_fill(node, parent_names, num_parents);

        clk = kzalloc(sizeof(*clk), GFP_KERNEL);
        if (!clk) {
                kfree(parent_names);
                return -ENOMEM;
        }

        clk->num_parents = num_parents;
        clk->parent_names = parent_names;
        clk->hw = hw;
        clk->node = node;
        clk->type = type;
        list_add(&clk->link, &component_clks);

        return 0;
}