// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
 *
 * Gated clock implementation
 */

#include <linux/clk-provider.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>
#include "clk.h"

/**
 * DOC: basic gateable clock which can gate and ungate its output
 *
 * Traits of this clock:
 * prepare - clk_(un)prepare only ensures parent is (un)prepared
 * enable - clk_enable and clk_disable are functional & control gating
 * rate - inherits rate from parent.  No clk_set_rate support
 * parent - fixed parent.  No clk_set_parent support
 */

struct clk_gate2 {
        struct clk_hw hw;
        void __iomem    *reg;
        u8              bit_idx;
        u8              cgr_val;
        u8              cgr_mask;
        u8              flags;
        spinlock_t      *lock;
        unsigned int    *share_count;
};

#define to_clk_gate2(_hw) container_of(_hw, struct clk_gate2, hw)

static void clk_gate2_do_shared_clks(struct clk_hw *hw, bool enable)
{
        struct clk_gate2 *gate = to_clk_gate2(hw);
        u32 reg;

        reg = readl(gate->reg);
        reg &= ~(gate->cgr_mask << gate->bit_idx);
        if (enable)
                reg |= (gate->cgr_val & gate->cgr_mask) << gate->bit_idx;
        writel(reg, gate->reg);
}

static int clk_gate2_enable(struct clk_hw *hw)
{
        struct clk_gate2 *gate = to_clk_gate2(hw);
        unsigned long flags;

        spin_lock_irqsave(gate->lock, flags);

        if (gate->share_count && (*gate->share_count)++ > 0)
                goto out;

        clk_gate2_do_shared_clks(hw, true);
out:
        spin_unlock_irqrestore(gate->lock, flags);

        return 0;
}

static void clk_gate2_disable(struct clk_hw *hw)
{
        struct clk_gate2 *gate = to_clk_gate2(hw);
        unsigned long flags;

        spin_lock_irqsave(gate->lock, flags);

        if (gate->share_count) {
                if (WARN_ON(*gate->share_count == 0))
                        goto out;
                else if (--(*gate->share_count) > 0)
                        goto out;
        }

        clk_gate2_do_shared_clks(hw, false);
out:
        spin_unlock_irqrestore(gate->lock, flags);
}

static int clk_gate2_reg_is_enabled(void __iomem *reg, u8 bit_idx,
                                        u8 cgr_val, u8 cgr_mask)
{
        u32 val = readl(reg);

        if (((val >> bit_idx) & cgr_mask) == cgr_val)
                return 1;

        return 0;
}

static int clk_gate2_is_enabled(struct clk_hw *hw)
{
        struct clk_gate2 *gate = to_clk_gate2(hw);
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(gate->lock, flags);

        ret = clk_gate2_reg_is_enabled(gate->reg, gate->bit_idx,
                                        gate->cgr_val, gate->cgr_mask);

        spin_unlock_irqrestore(gate->lock, flags);

        return ret;
}

static void clk_gate2_disable_unused(struct clk_hw *hw)
{
        struct clk_gate2 *gate = to_clk_gate2(hw);
        unsigned long flags;

        spin_lock_irqsave(gate->lock, flags);

        if (!gate->share_count || *gate->share_count == 0)
                clk_gate2_do_shared_clks(hw, false);

        spin_unlock_irqrestore(gate->lock, flags);
}

static const struct clk_ops clk_gate2_ops = {
        .enable = clk_gate2_enable,
        .disable = clk_gate2_disable,
        .disable_unused = clk_gate2_disable_unused,
        .is_enabled = clk_gate2_is_enabled,
};

struct clk_hw *clk_hw_register_gate2(struct device *dev, const char *name,
                const char *parent_name, unsigned long flags,
                void __iomem *reg, u8 bit_idx, u8 cgr_val, u8 cgr_mask,
                u8 clk_gate2_flags, spinlock_t *lock,
                unsigned int *share_count)
{
        struct clk_gate2 *gate;
        struct clk_hw *hw;
        struct clk_init_data init;
        int ret;

        gate = kzalloc_obj(struct clk_gate2);
        if (!gate)
                return ERR_PTR(-ENOMEM);

        /* struct clk_gate2 assignments */
        gate->reg = reg;
        gate->bit_idx = bit_idx;
        gate->cgr_val = cgr_val;
        gate->cgr_mask = cgr_mask;
        gate->flags = clk_gate2_flags;
        gate->lock = lock;
        gate->share_count = share_count;

        init.name = name;
        init.ops = &clk_gate2_ops;
        init.flags = flags;
        init.parent_names = parent_name ? &parent_name : NULL;
        init.num_parents = parent_name ? 1 : 0;

        gate->hw.init = &init;
        hw = &gate->hw;

        ret = clk_hw_register(dev, hw);
        if (ret) {
                kfree(gate);
                return ERR_PTR(ret);
        }

        return hw;
}
EXPORT_SYMBOL_GPL(clk_hw_register_gate2);