/*
 * TI clock autoidle 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 "clock.h"

struct clk_ti_autoidle {
        struct clk_omap_reg     reg;
        u8                      shift;
        u8                      flags;
        const char              *name;
        struct list_head        node;
};

#define AUTOIDLE_LOW            0x1

static LIST_HEAD(autoidle_clks);

/*
 * we have some non-atomic read/write
 * operations behind it, so lets
 * take one lock for handling autoidle
 * of all clocks
 */
static DEFINE_SPINLOCK(autoidle_spinlock);

static int _omap2_clk_deny_idle(struct clk_hw_omap *clk)
{
        if (clk->ops && clk->ops->deny_idle) {
                unsigned long irqflags;

                spin_lock_irqsave(&autoidle_spinlock, irqflags);
                clk->autoidle_count++;
                if (clk->autoidle_count == 1)
                        clk->ops->deny_idle(clk);

                spin_unlock_irqrestore(&autoidle_spinlock, irqflags);
        }
        return 0;
}

static int _omap2_clk_allow_idle(struct clk_hw_omap *clk)
{
        if (clk->ops && clk->ops->allow_idle) {
                unsigned long irqflags;

                spin_lock_irqsave(&autoidle_spinlock, irqflags);
                clk->autoidle_count--;
                if (clk->autoidle_count == 0)
                        clk->ops->allow_idle(clk);

                spin_unlock_irqrestore(&autoidle_spinlock, irqflags);
        }
        return 0;
}

/**
 * omap2_clk_deny_idle - disable autoidle on an OMAP clock
 * @clk: struct clk * to disable autoidle for
 *
 * Disable autoidle on an OMAP clock.
 */
int omap2_clk_deny_idle(struct clk *clk)
{
        struct clk_hw *hw;

        if (!clk)
                return -EINVAL;

        hw = __clk_get_hw(clk);

        if (omap2_clk_is_hw_omap(hw)) {
                struct clk_hw_omap *c = to_clk_hw_omap(hw);

                return _omap2_clk_deny_idle(c);
        }

        return -EINVAL;
}

/**
 * omap2_clk_allow_idle - enable autoidle on an OMAP clock
 * @clk: struct clk * to enable autoidle for
 *
 * Enable autoidle on an OMAP clock.
 */
int omap2_clk_allow_idle(struct clk *clk)
{
        struct clk_hw *hw;

        if (!clk)
                return -EINVAL;

        hw = __clk_get_hw(clk);

        if (omap2_clk_is_hw_omap(hw)) {
                struct clk_hw_omap *c = to_clk_hw_omap(hw);

                return _omap2_clk_allow_idle(c);
        }

        return -EINVAL;
}

static void _allow_autoidle(struct clk_ti_autoidle *clk)
{
        u32 val;

        val = ti_clk_ll_ops->clk_readl(&clk->reg);

        if (clk->flags & AUTOIDLE_LOW)
                val &= ~(1 << clk->shift);
        else
                val |= (1 << clk->shift);

        ti_clk_ll_ops->clk_writel(val, &clk->reg);
}

static void _deny_autoidle(struct clk_ti_autoidle *clk)
{
        u32 val;

        val = ti_clk_ll_ops->clk_readl(&clk->reg);

        if (clk->flags & AUTOIDLE_LOW)
                val |= (1 << clk->shift);
        else
                val &= ~(1 << clk->shift);

        ti_clk_ll_ops->clk_writel(val, &clk->reg);
}

/**
 * _clk_generic_allow_autoidle_all - enable autoidle for all clocks
 *
 * Enables hardware autoidle for all registered DT clocks, which have
 * the feature.
 */
static void _clk_generic_allow_autoidle_all(void)
{
        struct clk_ti_autoidle *c;

        list_for_each_entry(c, &autoidle_clks, node)
                _allow_autoidle(c);
}

/**
 * _clk_generic_deny_autoidle_all - disable autoidle for all clocks
 *
 * Disables hardware autoidle for all registered DT clocks, which have
 * the feature.
 */
static void _clk_generic_deny_autoidle_all(void)
{
        struct clk_ti_autoidle *c;

        list_for_each_entry(c, &autoidle_clks, node)
                _deny_autoidle(c);
}

/**
 * of_ti_clk_autoidle_setup - sets up hardware autoidle for a clock
 * @node: pointer to the clock device node
 *
 * Checks if a clock has hardware autoidle support or not (check
 * for presence of 'ti,autoidle-shift' property in the device tree
 * node) and sets up the hardware autoidle feature for the clock
 * if available. If autoidle is available, the clock is also added
 * to the autoidle list for later processing. Returns 0 on success,
 * negative error value on failure.
 */
int __init of_ti_clk_autoidle_setup(struct device_node *node)
{
        u32 shift;
        struct clk_ti_autoidle *clk;
        int ret;

        /* Check if this clock has autoidle support or not */
        if (of_property_read_u32(node, "ti,autoidle-shift", &shift))
                return 0;

        clk = kzalloc(sizeof(*clk), GFP_KERNEL);

        if (!clk)
                return -ENOMEM;

        clk->shift = shift;
        clk->name = node->name;
        ret = ti_clk_get_reg_addr(node, 0, &clk->reg);
        if (ret) {
                kfree(clk);
                return ret;
        }

        if (of_property_read_bool(node, "ti,invert-autoidle-bit"))
                clk->flags |= AUTOIDLE_LOW;

        list_add(&clk->node, &autoidle_clks);

        return 0;
}

/**
 * omap2_clk_enable_autoidle_all - enable autoidle on all OMAP clocks that
 * support it
 *
 * Enable clock autoidle on all OMAP clocks that have allow_idle
 * function pointers associated with them.  This function is intended
 * to be temporary until support for this is added to the common clock
 * code.  Returns 0.
 */
int omap2_clk_enable_autoidle_all(void)
{
        int ret;

        ret = omap2_clk_for_each(_omap2_clk_allow_idle);
        if (ret)
                return ret;

        _clk_generic_allow_autoidle_all();

        return 0;
}

/**
 * omap2_clk_disable_autoidle_all - disable autoidle on all OMAP clocks that
 * support it
 *
 * Disable clock autoidle on all OMAP clocks that have allow_idle
 * function pointers associated with them.  This function is intended
 * to be temporary until support for this is added to the common clock
 * code.  Returns 0.
 */
int omap2_clk_disable_autoidle_all(void)
{
        int ret;

        ret = omap2_clk_for_each(_omap2_clk_deny_idle);
        if (ret)
                return ret;

        _clk_generic_deny_autoidle_all();

        return 0;
}