// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018 MediaTek Inc.
 * Author: Owen Chen <owen.chen@mediatek.com>
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/compiler_types.h>
#include <linux/container_of.h>
#include <linux/err.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/spinlock.h>
#include <linux/slab.h>

#include "clk-mux.h"

struct mtk_clk_mux {
	struct clk_hw hw;
	struct regmap *regmap;
	const struct mtk_mux *data;
	spinlock_t *lock;
	bool reparent;
};

static inline struct mtk_clk_mux *to_mtk_clk_mux(struct clk_hw *hw)
{
	return container_of(hw, struct mtk_clk_mux, hw);
}

static int mtk_clk_mux_enable_setclr(struct clk_hw *hw)
{
	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
	unsigned long flags = 0;

	if (mux->lock)
		spin_lock_irqsave(mux->lock, flags);
	else
		__acquire(mux->lock);

	regmap_write(mux->regmap, mux->data->clr_ofs,
		     BIT(mux->data->gate_shift));

	/*
	 * If the parent has been changed when the clock was disabled, it will
	 * not be effective yet. Set the update bit to ensure the mux gets
	 * updated.
	 */
	if (mux->reparent && mux->data->upd_shift >= 0) {
		regmap_write(mux->regmap, mux->data->upd_ofs,
			     BIT(mux->data->upd_shift));
		mux->reparent = false;
	}

	if (mux->lock)
		spin_unlock_irqrestore(mux->lock, flags);
	else
		__release(mux->lock);

	return 0;
}

static void mtk_clk_mux_disable_setclr(struct clk_hw *hw)
{
	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);

	regmap_write(mux->regmap, mux->data->set_ofs,
			BIT(mux->data->gate_shift));
}

static int mtk_clk_mux_is_enabled(struct clk_hw *hw)
{
	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
	u32 val;

	regmap_read(mux->regmap, mux->data->mux_ofs, &val);

	return (val & BIT(mux->data->gate_shift)) == 0;
}

static u8 mtk_clk_mux_get_parent(struct clk_hw *hw)
{
	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
	u32 mask = GENMASK(mux->data->mux_width - 1, 0);
	u32 val;

	regmap_read(mux->regmap, mux->data->mux_ofs, &val);
	val = (val >> mux->data->mux_shift) & mask;

	if (mux->data->parent_index) {
		int i;

		for (i = 0; i < mux->data->num_parents; i++)
			if (mux->data->parent_index[i] == val)
				return i;

		/* Not found: return an impossible index to generate error */
		return mux->data->num_parents + 1;
	}

	return val;
}

static int mtk_clk_mux_set_parent_setclr_lock(struct clk_hw *hw, u8 index)
{
	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);
	u32 mask = GENMASK(mux->data->mux_width - 1, 0);
	u32 val, orig;
	unsigned long flags = 0;

	if (mux->lock)
		spin_lock_irqsave(mux->lock, flags);
	else
		__acquire(mux->lock);

	if (mux->data->parent_index)
		index = mux->data->parent_index[index];

	regmap_read(mux->regmap, mux->data->mux_ofs, &orig);
	val = (orig & ~(mask << mux->data->mux_shift))
			| (index << mux->data->mux_shift);

	if (val != orig) {
		regmap_write(mux->regmap, mux->data->clr_ofs,
				mask << mux->data->mux_shift);
		regmap_write(mux->regmap, mux->data->set_ofs,
				index << mux->data->mux_shift);

		if (mux->data->upd_shift >= 0) {
			regmap_write(mux->regmap, mux->data->upd_ofs,
					BIT(mux->data->upd_shift));
			mux->reparent = true;
		}
	}

	if (mux->lock)
		spin_unlock_irqrestore(mux->lock, flags);
	else
		__release(mux->lock);

	return 0;
}

static int mtk_clk_mux_determine_rate(struct clk_hw *hw,
				      struct clk_rate_request *req)
{
	struct mtk_clk_mux *mux = to_mtk_clk_mux(hw);

	return clk_mux_determine_rate_flags(hw, req, mux->data->flags);
}

const struct clk_ops mtk_mux_clr_set_upd_ops = {
	.get_parent = mtk_clk_mux_get_parent,
	.set_parent = mtk_clk_mux_set_parent_setclr_lock,
	.determine_rate = mtk_clk_mux_determine_rate,
};
EXPORT_SYMBOL_GPL(mtk_mux_clr_set_upd_ops);

const struct clk_ops mtk_mux_gate_clr_set_upd_ops  = {
	.enable = mtk_clk_mux_enable_setclr,
	.disable = mtk_clk_mux_disable_setclr,
	.is_enabled = mtk_clk_mux_is_enabled,
	.get_parent = mtk_clk_mux_get_parent,
	.set_parent = mtk_clk_mux_set_parent_setclr_lock,
	.determine_rate = mtk_clk_mux_determine_rate,
};
EXPORT_SYMBOL_GPL(mtk_mux_gate_clr_set_upd_ops);

static struct clk_hw *mtk_clk_register_mux(struct device *dev,
					   const struct mtk_mux *mux,
					   struct regmap *regmap,
					   spinlock_t *lock)
{
	struct mtk_clk_mux *clk_mux;
	struct clk_init_data init = {};
	int ret;

	clk_mux = kzalloc(sizeof(*clk_mux), GFP_KERNEL);
	if (!clk_mux)
		return ERR_PTR(-ENOMEM);

	init.name = mux->name;
	init.flags = mux->flags;
	init.parent_names = mux->parent_names;
	init.num_parents = mux->num_parents;
	init.ops = mux->ops;

	clk_mux->regmap = regmap;
	clk_mux->data = mux;
	clk_mux->lock = lock;
	clk_mux->hw.init = &init;

	ret = clk_hw_register(dev, &clk_mux->hw);
	if (ret) {
		kfree(clk_mux);
		return ERR_PTR(ret);
	}

	return &clk_mux->hw;
}

static void mtk_clk_unregister_mux(struct clk_hw *hw)
{
	struct mtk_clk_mux *mux;
	if (!hw)
		return;

	mux = to_mtk_clk_mux(hw);

	clk_hw_unregister(hw);
	kfree(mux);
}

int mtk_clk_register_muxes(struct device *dev,
			   const struct mtk_mux *muxes,
			   int num, struct device_node *node,
			   spinlock_t *lock,
			   struct clk_hw_onecell_data *clk_data)
{
	struct regmap *regmap;
	struct clk_hw *hw;
	int i;

	regmap = device_node_to_regmap(node);
	if (IS_ERR(regmap)) {
		pr_err("Cannot find regmap for %pOF: %pe\n", node, regmap);
		return PTR_ERR(regmap);
	}

	for (i = 0; i < num; i++) {
		const struct mtk_mux *mux = &muxes[i];

		if (!IS_ERR_OR_NULL(clk_data->hws[mux->id])) {
			pr_warn("%pOF: Trying to register duplicate clock ID: %d\n",
				node, mux->id);
			continue;
		}

		hw = mtk_clk_register_mux(dev, mux, regmap, lock);

		if (IS_ERR(hw)) {
			pr_err("Failed to register clk %s: %pe\n", mux->name,
			       hw);
			goto err;
		}

		clk_data->hws[mux->id] = hw;
	}

	return 0;

err:
	while (--i >= 0) {
		const struct mtk_mux *mux = &muxes[i];

		if (IS_ERR_OR_NULL(clk_data->hws[mux->id]))
			continue;

		mtk_clk_unregister_mux(clk_data->hws[mux->id]);
		clk_data->hws[mux->id] = ERR_PTR(-ENOENT);
	}

	return PTR_ERR(hw);
}
EXPORT_SYMBOL_GPL(mtk_clk_register_muxes);

void mtk_clk_unregister_muxes(const struct mtk_mux *muxes, int num,
			      struct clk_hw_onecell_data *clk_data)
{
	int i;

	if (!clk_data)
		return;

	for (i = num; i > 0; i--) {
		const struct mtk_mux *mux = &muxes[i - 1];

		if (IS_ERR_OR_NULL(clk_data->hws[mux->id]))
			continue;

		mtk_clk_unregister_mux(clk_data->hws[mux->id]);
		clk_data->hws[mux->id] = ERR_PTR(-ENOENT);
	}
}
EXPORT_SYMBOL_GPL(mtk_clk_unregister_muxes);

/*
 * This clock notifier is called when the frequency of the parent
 * PLL clock is to be changed. The idea is to switch the parent to a
 * stable clock, such as the main oscillator, while the PLL frequency
 * stabilizes.
 */
static int mtk_clk_mux_notifier_cb(struct notifier_block *nb,
				   unsigned long event, void *_data)
{
	struct clk_notifier_data *data = _data;
	struct clk_hw *hw = __clk_get_hw(data->clk);
	struct mtk_mux_nb *mux_nb = to_mtk_mux_nb(nb);
	int ret = 0;

	switch (event) {
	case PRE_RATE_CHANGE:
		mux_nb->original_index = mux_nb->ops->get_parent(hw);
		ret = mux_nb->ops->set_parent(hw, mux_nb->bypass_index);
		break;
	case POST_RATE_CHANGE:
	case ABORT_RATE_CHANGE:
		ret = mux_nb->ops->set_parent(hw, mux_nb->original_index);
		break;
	}

	return notifier_from_errno(ret);
}

int devm_mtk_clk_mux_notifier_register(struct device *dev, struct clk *clk,
				       struct mtk_mux_nb *mux_nb)
{
	mux_nb->nb.notifier_call = mtk_clk_mux_notifier_cb;

	return devm_clk_notifier_register(dev, clk, &mux_nb->nb);
}
EXPORT_SYMBOL_GPL(devm_mtk_clk_mux_notifier_register);

MODULE_LICENSE("GPL");