// SPDX-License-Identifier: GPL-2.0-only
/*
 * Toshiba Visconti PLL driver
 *
 * Copyright (c) 2021 TOSHIBA CORPORATION
 * Copyright (c) 2021 Toshiba Electronic Devices & Storage Corporation
 *
 * Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
 */

#include <linux/bitfield.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/io.h>

#include "pll.h"

struct visconti_pll {
	struct clk_hw	hw;
	void __iomem	*pll_base;
	spinlock_t	*lock;
	unsigned long flags;
	const struct visconti_pll_rate_table *rate_table;
	size_t rate_count;
	struct visconti_pll_provider *ctx;
};

#define PLL_CONF_REG		0x0000
#define PLL_CTRL_REG		0x0004
#define PLL_FRACMODE_REG	0x0010
#define PLL_INTIN_REG		0x0014
#define PLL_FRACIN_REG		0x0018
#define PLL_REFDIV_REG		0x001c
#define PLL_POSTDIV_REG		0x0020

#define PLL_CONFIG_SEL		BIT(0)
#define PLL_PLLEN		BIT(4)
#define PLL_BYPASS		BIT(16)
#define PLL_INTIN_MASK		GENMASK(11, 0)
#define PLL_FRACIN_MASK		GENMASK(23, 0)
#define PLL_REFDIV_MASK		GENMASK(5, 0)
#define PLL_POSTDIV_MASK	GENMASK(2, 0)

#define PLL0_FRACMODE_DACEN	BIT(4)
#define PLL0_FRACMODE_DSMEN	BIT(0)

#define PLL_CREATE_FRACMODE(table) (table->dacen << 4 | table->dsmen)
#define PLL_CREATE_OSTDIV(table) (table->postdiv2 << 4 | table->postdiv1)

static inline struct visconti_pll *to_visconti_pll(struct clk_hw *hw)
{
	return container_of(hw, struct visconti_pll, hw);
}

static void visconti_pll_get_params(struct visconti_pll *pll,
				    struct visconti_pll_rate_table *rate_table)
{
	u32 postdiv, val;

	val = readl(pll->pll_base + PLL_FRACMODE_REG);

	rate_table->dacen = FIELD_GET(PLL0_FRACMODE_DACEN, val);
	rate_table->dsmen = FIELD_GET(PLL0_FRACMODE_DSMEN, val);

	rate_table->fracin = readl(pll->pll_base + PLL_FRACIN_REG) & PLL_FRACIN_MASK;
	rate_table->intin = readl(pll->pll_base + PLL_INTIN_REG) & PLL_INTIN_MASK;
	rate_table->refdiv = readl(pll->pll_base + PLL_REFDIV_REG) & PLL_REFDIV_MASK;

	postdiv = readl(pll->pll_base + PLL_POSTDIV_REG);
	rate_table->postdiv1 = postdiv & PLL_POSTDIV_MASK;
	rate_table->postdiv2 = (postdiv >> 4) & PLL_POSTDIV_MASK;
}

static const struct visconti_pll_rate_table *visconti_get_pll_settings(struct visconti_pll *pll,
								       unsigned long rate)
{
	const struct visconti_pll_rate_table *rate_table = pll->rate_table;
	int i;

	for (i = 0; i < pll->rate_count; i++)
		if (rate == rate_table[i].rate)
			return &rate_table[i];

	return NULL;
}

static unsigned long visconti_get_pll_rate_from_data(struct visconti_pll *pll,
						     const struct visconti_pll_rate_table *rate)
{
	const struct visconti_pll_rate_table *rate_table = pll->rate_table;
	int i;

	for (i = 0; i < pll->rate_count; i++)
		if (memcmp(&rate_table[i].dacen, &rate->dacen,
			sizeof(*rate) - sizeof(unsigned long)) == 0)
			return rate_table[i].rate;

	/* set default */
	return rate_table[0].rate;
}

static long visconti_pll_round_rate(struct clk_hw *hw,
				    unsigned long rate, unsigned long *prate)
{
	struct visconti_pll *pll = to_visconti_pll(hw);
	const struct visconti_pll_rate_table *rate_table = pll->rate_table;
	int i;

	/* Assumming rate_table is in descending order */
	for (i = 0; i < pll->rate_count; i++)
		if (rate >= rate_table[i].rate)
			return rate_table[i].rate;

	/* return minimum supported value */
	return rate_table[i - 1].rate;
}

static unsigned long visconti_pll_recalc_rate(struct clk_hw *hw,
					      unsigned long parent_rate)
{
	struct visconti_pll *pll = to_visconti_pll(hw);
	struct visconti_pll_rate_table rate_table;

	memset(&rate_table, 0, sizeof(rate_table));
	visconti_pll_get_params(pll, &rate_table);

	return visconti_get_pll_rate_from_data(pll, &rate_table);
}

static int visconti_pll_set_params(struct visconti_pll *pll,
				   const struct visconti_pll_rate_table *rate_table)
{
	writel(PLL_CREATE_FRACMODE(rate_table), pll->pll_base + PLL_FRACMODE_REG);
	writel(PLL_CREATE_OSTDIV(rate_table), pll->pll_base + PLL_POSTDIV_REG);
	writel(rate_table->intin, pll->pll_base + PLL_INTIN_REG);
	writel(rate_table->fracin, pll->pll_base + PLL_FRACIN_REG);
	writel(rate_table->refdiv, pll->pll_base + PLL_REFDIV_REG);

	return 0;
}

static int visconti_pll_set_rate(struct clk_hw *hw, unsigned long rate,
			    unsigned long parent_rate)
{
	struct visconti_pll *pll = to_visconti_pll(hw);
	const struct visconti_pll_rate_table *rate_table;

	rate_table = visconti_get_pll_settings(pll, rate);
	if (!rate_table)
		return -EINVAL;

	return visconti_pll_set_params(pll, rate_table);
}

static int visconti_pll_is_enabled(struct clk_hw *hw)
{
	struct visconti_pll *pll = to_visconti_pll(hw);
	u32 reg;

	reg = readl(pll->pll_base + PLL_CTRL_REG);

	return (reg & PLL_PLLEN);
}

static int visconti_pll_enable(struct clk_hw *hw)
{
	struct visconti_pll *pll = to_visconti_pll(hw);
	const struct visconti_pll_rate_table *rate_table = pll->rate_table;
	unsigned long flags;
	u32 reg;

	if (visconti_pll_is_enabled(hw))
		return 0;

	spin_lock_irqsave(pll->lock, flags);

	writel(PLL_CONFIG_SEL, pll->pll_base + PLL_CONF_REG);

	reg = readl(pll->pll_base + PLL_CTRL_REG);
	reg |= PLL_BYPASS;
	writel(reg, pll->pll_base + PLL_CTRL_REG);

	visconti_pll_set_params(pll, &rate_table[0]);

	reg = readl(pll->pll_base + PLL_CTRL_REG);
	reg &= ~PLL_PLLEN;
	writel(reg, pll->pll_base + PLL_CTRL_REG);

	udelay(1);

	reg = readl(pll->pll_base + PLL_CTRL_REG);
	reg |= PLL_PLLEN;
	writel(reg, pll->pll_base + PLL_CTRL_REG);

	udelay(40);

	reg = readl(pll->pll_base + PLL_CTRL_REG);
	reg &= ~PLL_BYPASS;
	writel(reg, pll->pll_base + PLL_CTRL_REG);

	spin_unlock_irqrestore(pll->lock, flags);

	return 0;
}

static void visconti_pll_disable(struct clk_hw *hw)
{
	struct visconti_pll *pll = to_visconti_pll(hw);
	unsigned long flags;
	u32 reg;

	if (!visconti_pll_is_enabled(hw))
		return;

	spin_lock_irqsave(pll->lock, flags);

	writel(PLL_CONFIG_SEL, pll->pll_base + PLL_CONF_REG);

	reg = readl(pll->pll_base + PLL_CTRL_REG);
	reg |= PLL_BYPASS;
	writel(reg, pll->pll_base + PLL_CTRL_REG);

	reg = readl(pll->pll_base + PLL_CTRL_REG);
	reg &= ~PLL_PLLEN;
	writel(reg, pll->pll_base + PLL_CTRL_REG);

	spin_unlock_irqrestore(pll->lock, flags);
}

static const struct clk_ops visconti_pll_ops = {
	.enable = visconti_pll_enable,
	.disable = visconti_pll_disable,
	.is_enabled = visconti_pll_is_enabled,
	.round_rate = visconti_pll_round_rate,
	.recalc_rate = visconti_pll_recalc_rate,
	.set_rate = visconti_pll_set_rate,
};

static struct clk_hw *visconti_register_pll(struct visconti_pll_provider *ctx,
					    const char *name,
					    const char *parent_name,
					    int offset,
					    const struct visconti_pll_rate_table *rate_table,
					    spinlock_t *lock)
{
	struct clk_init_data init;
	struct visconti_pll *pll;
	struct clk *pll_clk;
	struct clk_hw *pll_hw_clk;
	size_t len;
	int ret;

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

	init.name = name;
	init.flags = CLK_IGNORE_UNUSED;
	init.parent_names = &parent_name;
	init.num_parents = 1;

	for (len = 0; rate_table[len].rate != 0; )
		len++;
	pll->rate_count = len;
	pll->rate_table = kmemdup(rate_table,
				  pll->rate_count * sizeof(struct visconti_pll_rate_table),
				  GFP_KERNEL);
	WARN(!pll->rate_table, "%s: could not allocate rate table for %s\n", __func__, name);

	init.ops = &visconti_pll_ops;
	pll->hw.init = &init;
	pll->pll_base = ctx->reg_base + offset;
	pll->lock = lock;
	pll->ctx = ctx;

	pll_hw_clk = &pll->hw;
	ret = clk_hw_register(NULL, &pll->hw);
	if (ret) {
		pr_err("failed to register pll clock %s : %ld\n", name, PTR_ERR(pll_clk));
		kfree(pll);
		pll_hw_clk = ERR_PTR(ret);
	}

	return pll_hw_clk;
}

static void visconti_pll_add_lookup(struct visconti_pll_provider *ctx,
				    struct clk_hw *hw_clk,
				    unsigned int id)
{
	if (id)
		ctx->clk_data.hws[id] = hw_clk;
}

void __init visconti_register_plls(struct visconti_pll_provider *ctx,
				   const struct visconti_pll_info *list,
				   unsigned int nr_plls,
				   spinlock_t *lock)
{
	int idx;

	for (idx = 0; idx < nr_plls; idx++, list++) {
		struct clk_hw *clk;

		clk = visconti_register_pll(ctx,
					    list->name,
					    list->parent,
					    list->base_reg,
					    list->rate_table,
					    lock);
		if (IS_ERR(clk)) {
			pr_err("failed to register clock %s\n", list->name);
			continue;
		}

		visconti_pll_add_lookup(ctx, clk, list->id);
	}
}

struct visconti_pll_provider * __init visconti_init_pll(struct device_node *np,
							void __iomem *base,
							unsigned long nr_plls)
{
	struct visconti_pll_provider *ctx;
	int i;

	ctx = kzalloc(struct_size(ctx, clk_data.hws, nr_plls), GFP_KERNEL);
	if (!ctx)
		return ERR_PTR(-ENOMEM);

	for (i = 0; i < nr_plls; ++i)
		ctx->clk_data.hws[i] = ERR_PTR(-ENOENT);

	ctx->node = np;
	ctx->reg_base = base;
	ctx->clk_data.num = nr_plls;

	return ctx;
}