/*
 * R-Car Gen2 Clock Pulse Generator
 *
 * Copyright (C) 2016 Cogent Embedded Inc.
 *
 * 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.
 */

#include <linux/bug.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/slab.h>

#include "renesas-cpg-mssr.h"
#include "rcar-gen2-cpg.h"

#define CPG_FRQCRB		0x0004
#define CPG_FRQCRB_KICK		BIT(31)
#define CPG_SDCKCR		0x0074
#define CPG_PLL0CR		0x00d8
#define CPG_PLL0CR_STC_SHIFT	24
#define CPG_PLL0CR_STC_MASK	(0x7f << CPG_PLL0CR_STC_SHIFT)
#define CPG_FRQCRC		0x00e0
#define CPG_FRQCRC_ZFC_SHIFT	8
#define CPG_FRQCRC_ZFC_MASK	(0x1f << CPG_FRQCRC_ZFC_SHIFT)
#define CPG_ADSPCKCR		0x025c
#define CPG_RCANCKCR		0x0270

static spinlock_t cpg_lock;

/*
 * Z Clock
 *
 * Traits of this clock:
 * prepare - clk_prepare only ensures that parents are prepared
 * enable - clk_enable only ensures that parents are enabled
 * rate - rate is adjustable.  clk->rate = parent->rate * mult / 32
 * parent - fixed parent.  No clk_set_parent support
 */

struct cpg_z_clk {
	struct clk_hw hw;
	void __iomem *reg;
	void __iomem *kick_reg;
};

#define to_z_clk(_hw)	container_of(_hw, struct cpg_z_clk, hw)

static unsigned long cpg_z_clk_recalc_rate(struct clk_hw *hw,
					   unsigned long parent_rate)
{
	struct cpg_z_clk *zclk = to_z_clk(hw);
	unsigned int mult;
	unsigned int val;

	val = (readl(zclk->reg) & CPG_FRQCRC_ZFC_MASK) >> CPG_FRQCRC_ZFC_SHIFT;
	mult = 32 - val;

	return div_u64((u64)parent_rate * mult, 32);
}

static long cpg_z_clk_round_rate(struct clk_hw *hw, unsigned long rate,
				 unsigned long *parent_rate)
{
	unsigned long prate  = *parent_rate;
	unsigned int mult;

	if (!prate)
		prate = 1;

	mult = div_u64((u64)rate * 32, prate);
	mult = clamp(mult, 1U, 32U);

	return *parent_rate / 32 * mult;
}

static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate,
			      unsigned long parent_rate)
{
	struct cpg_z_clk *zclk = to_z_clk(hw);
	unsigned int mult;
	u32 val, kick;
	unsigned int i;

	mult = div_u64((u64)rate * 32, parent_rate);
	mult = clamp(mult, 1U, 32U);

	if (readl(zclk->kick_reg) & CPG_FRQCRB_KICK)
		return -EBUSY;

	val = readl(zclk->reg);
	val &= ~CPG_FRQCRC_ZFC_MASK;
	val |= (32 - mult) << CPG_FRQCRC_ZFC_SHIFT;
	writel(val, zclk->reg);

	/*
	 * Set KICK bit in FRQCRB to update hardware setting and wait for
	 * clock change completion.
	 */
	kick = readl(zclk->kick_reg);
	kick |= CPG_FRQCRB_KICK;
	writel(kick, zclk->kick_reg);

	/*
	 * Note: There is no HW information about the worst case latency.
	 *
	 * Using experimental measurements, it seems that no more than
	 * ~10 iterations are needed, independently of the CPU rate.
	 * Since this value might be dependent on external xtal rate, pll1
	 * rate or even the other emulation clocks rate, use 1000 as a
	 * "super" safe value.
	 */
	for (i = 1000; i; i--) {
		if (!(readl(zclk->kick_reg) & CPG_FRQCRB_KICK))
			return 0;

		cpu_relax();
	}

	return -ETIMEDOUT;
}

static const struct clk_ops cpg_z_clk_ops = {
	.recalc_rate = cpg_z_clk_recalc_rate,
	.round_rate = cpg_z_clk_round_rate,
	.set_rate = cpg_z_clk_set_rate,
};

static struct clk * __init cpg_z_clk_register(const char *name,
					      const char *parent_name,
					      void __iomem *base)
{
	struct clk_init_data init;
	struct cpg_z_clk *zclk;
	struct clk *clk;

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

	init.name = name;
	init.ops = &cpg_z_clk_ops;
	init.flags = 0;
	init.parent_names = &parent_name;
	init.num_parents = 1;

	zclk->reg = base + CPG_FRQCRC;
	zclk->kick_reg = base + CPG_FRQCRB;
	zclk->hw.init = &init;

	clk = clk_register(NULL, &zclk->hw);
	if (IS_ERR(clk))
		kfree(zclk);

	return clk;
}

static struct clk * __init cpg_rcan_clk_register(const char *name,
						 const char *parent_name,
						 void __iomem *base)
{
	struct clk_fixed_factor *fixed;
	struct clk_gate *gate;
	struct clk *clk;

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

	fixed->mult = 1;
	fixed->div = 6;

	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
	if (!gate) {
		kfree(fixed);
		return ERR_PTR(-ENOMEM);
	}

	gate->reg = base + CPG_RCANCKCR;
	gate->bit_idx = 8;
	gate->flags = CLK_GATE_SET_TO_DISABLE;
	gate->lock = &cpg_lock;

	clk = clk_register_composite(NULL, name, &parent_name, 1, NULL, NULL,
				     &fixed->hw, &clk_fixed_factor_ops,
				     &gate->hw, &clk_gate_ops, 0);
	if (IS_ERR(clk)) {
		kfree(gate);
		kfree(fixed);
	}

	return clk;
}

/* ADSP divisors */
static const struct clk_div_table cpg_adsp_div_table[] = {
	{  1,  3 }, {  2,  4 }, {  3,  6 }, {  4,  8 },
	{  5, 12 }, {  6, 16 }, {  7, 18 }, {  8, 24 },
	{ 10, 36 }, { 11, 48 }, {  0,  0 },
};

static struct clk * __init cpg_adsp_clk_register(const char *name,
						 const char *parent_name,
						 void __iomem *base)
{
	struct clk_divider *div;
	struct clk_gate *gate;
	struct clk *clk;

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

	div->reg = base + CPG_ADSPCKCR;
	div->width = 4;
	div->table = cpg_adsp_div_table;
	div->lock = &cpg_lock;

	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
	if (!gate) {
		kfree(div);
		return ERR_PTR(-ENOMEM);
	}

	gate->reg = base + CPG_ADSPCKCR;
	gate->bit_idx = 8;
	gate->flags = CLK_GATE_SET_TO_DISABLE;
	gate->lock = &cpg_lock;

	clk = clk_register_composite(NULL, name, &parent_name, 1, NULL, NULL,
				     &div->hw, &clk_divider_ops,
				     &gate->hw, &clk_gate_ops, 0);
	if (IS_ERR(clk)) {
		kfree(gate);
		kfree(div);
	}

	return clk;
}

/* SDHI divisors */
static const struct clk_div_table cpg_sdh_div_table[] = {
	{  0,  2 }, {  1,  3 }, {  2,  4 }, {  3,  6 },
	{  4,  8 }, {  5, 12 }, {  6, 16 }, {  7, 18 },
	{  8, 24 }, { 10, 36 }, { 11, 48 }, {  0,  0 },
};

static const struct clk_div_table cpg_sd01_div_table[] = {
	{  4,  8 }, {  5, 12 }, {  6, 16 }, {  7, 18 },
	{  8, 24 }, { 10, 36 }, { 11, 48 }, { 12, 10 },
	{  0,  0 },
};

static const struct rcar_gen2_cpg_pll_config *cpg_pll_config __initdata;
static unsigned int cpg_pll0_div __initdata;
static u32 cpg_mode __initdata;

struct clk * __init rcar_gen2_cpg_clk_register(struct device *dev,
					       const struct cpg_core_clk *core,
					       const struct cpg_mssr_info *info,
					       struct clk **clks,
					       void __iomem *base)
{
	const struct clk_div_table *table = NULL;
	const struct clk *parent;
	const char *parent_name;
	unsigned int mult = 1;
	unsigned int div = 1;
	unsigned int shift;

	parent = clks[core->parent];
	if (IS_ERR(parent))
		return ERR_CAST(parent);

	parent_name = __clk_get_name(parent);

	switch (core->type) {
	/* R-Car Gen2 */
	case CLK_TYPE_GEN2_MAIN:
		div = cpg_pll_config->extal_div;
		break;

	case CLK_TYPE_GEN2_PLL0:
		/*
		 * PLL0 is a  configurable multiplier clock except on R-Car
		 * V2H/E2. Register the PLL0 clock as a fixed factor clock for
		 * now as there's no generic multiplier clock implementation and
		 * we  currently  have no need to change  the multiplier value.
		 */
		mult = cpg_pll_config->pll0_mult;
		div  = cpg_pll0_div;
		if (!mult) {
			u32 pll0cr = readl(base + CPG_PLL0CR);

			mult = (((pll0cr & CPG_PLL0CR_STC_MASK) >>
				 CPG_PLL0CR_STC_SHIFT) + 1) * 2;
		}
		break;

	case CLK_TYPE_GEN2_PLL1:
		mult = cpg_pll_config->pll1_mult / 2;
		break;

	case CLK_TYPE_GEN2_PLL3:
		mult = cpg_pll_config->pll3_mult;
		break;

	case CLK_TYPE_GEN2_Z:
		return cpg_z_clk_register(core->name, parent_name, base);

	case CLK_TYPE_GEN2_LB:
		div = cpg_mode & BIT(18) ? 36 : 24;
		break;

	case CLK_TYPE_GEN2_ADSP:
		return cpg_adsp_clk_register(core->name, parent_name, base);

	case CLK_TYPE_GEN2_SDH:
		table = cpg_sdh_div_table;
		shift = 8;
		break;

	case CLK_TYPE_GEN2_SD0:
		table = cpg_sd01_div_table;
		shift = 4;
		break;

	case CLK_TYPE_GEN2_SD1:
		table = cpg_sd01_div_table;
		shift = 0;
		break;

	case CLK_TYPE_GEN2_QSPI:
		div = (cpg_mode & (BIT(3) | BIT(2) | BIT(1))) == BIT(2) ?
		      8 : 10;
		break;

	case CLK_TYPE_GEN2_RCAN:
		return cpg_rcan_clk_register(core->name, parent_name, base);

	default:
		return ERR_PTR(-EINVAL);
	}

	if (!table)
		return clk_register_fixed_factor(NULL, core->name, parent_name,
						 0, mult, div);
	else
		return clk_register_divider_table(NULL, core->name,
						  parent_name, 0,
						  base + CPG_SDCKCR, shift, 4,
						  0, table, &cpg_lock);
}

int __init rcar_gen2_cpg_init(const struct rcar_gen2_cpg_pll_config *config,
			      unsigned int pll0_div, u32 mode)
{
	cpg_pll_config = config;
	cpg_pll0_div = pll0_div;
	cpg_mode = mode;

	spin_lock_init(&cpg_lock);

	return 0;
}