/*
 * MVEBU Core divider clock
 *
 * Copyright (C) 2013 Marvell
 *
 * Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/clk-provider.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include "common.h"

#define CORE_CLK_DIV_RATIO_MASK		0xff

/*
 * This structure describes the hardware details (bit offset and mask)
 * to configure one particular core divider clock. Those hardware
 * details may differ from one SoC to another. This structure is
 * therefore typically instantiated statically to describe the
 * hardware details.
 */
struct clk_corediv_desc {
	unsigned int mask;
	unsigned int offset;
	unsigned int fieldbit;
};

/*
 * This structure describes the hardware details to configure the core
 * divider clocks on a given SoC. Amongst others, it points to the
 * array of core divider clock descriptors for this SoC, as well as
 * the corresponding operations to manipulate them.
 */
struct clk_corediv_soc_desc {
	const struct clk_corediv_desc *descs;
	unsigned int ndescs;
	const struct clk_ops ops;
	u32 ratio_reload;
	u32 enable_bit_offset;
	u32 ratio_offset;
};

/*
 * This structure represents one core divider clock for the clock
 * framework, and is dynamically allocated for each core divider clock
 * existing in the current SoC.
 */
struct clk_corediv {
	struct clk_hw hw;
	void __iomem *reg;
	const struct clk_corediv_desc *desc;
	const struct clk_corediv_soc_desc *soc_desc;
	spinlock_t lock;
};

static struct clk_onecell_data clk_data;

/*
 * Description of the core divider clocks available. For now, we
 * support only NAND, and it is available at the same register
 * locations regardless of the SoC.
 */
static const struct clk_corediv_desc mvebu_corediv_desc[] = {
	{ .mask = 0x3f, .offset = 8, .fieldbit = 1 }, /* NAND clock */
};

#define to_corediv_clk(p) container_of(p, struct clk_corediv, hw)

static int clk_corediv_is_enabled(struct clk_hw *hwclk)
{
	struct clk_corediv *corediv = to_corediv_clk(hwclk);
	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
	const struct clk_corediv_desc *desc = corediv->desc;
	u32 enable_mask = BIT(desc->fieldbit) << soc_desc->enable_bit_offset;

	return !!(readl(corediv->reg) & enable_mask);
}

static int clk_corediv_enable(struct clk_hw *hwclk)
{
	struct clk_corediv *corediv = to_corediv_clk(hwclk);
	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
	const struct clk_corediv_desc *desc = corediv->desc;
	unsigned long flags = 0;
	u32 reg;

	spin_lock_irqsave(&corediv->lock, flags);

	reg = readl(corediv->reg);
	reg |= (BIT(desc->fieldbit) << soc_desc->enable_bit_offset);
	writel(reg, corediv->reg);

	spin_unlock_irqrestore(&corediv->lock, flags);

	return 0;
}

static void clk_corediv_disable(struct clk_hw *hwclk)
{
	struct clk_corediv *corediv = to_corediv_clk(hwclk);
	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
	const struct clk_corediv_desc *desc = corediv->desc;
	unsigned long flags = 0;
	u32 reg;

	spin_lock_irqsave(&corediv->lock, flags);

	reg = readl(corediv->reg);
	reg &= ~(BIT(desc->fieldbit) << soc_desc->enable_bit_offset);
	writel(reg, corediv->reg);

	spin_unlock_irqrestore(&corediv->lock, flags);
}

static unsigned long clk_corediv_recalc_rate(struct clk_hw *hwclk,
					 unsigned long parent_rate)
{
	struct clk_corediv *corediv = to_corediv_clk(hwclk);
	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
	const struct clk_corediv_desc *desc = corediv->desc;
	u32 reg, div;

	reg = readl(corediv->reg + soc_desc->ratio_offset);
	div = (reg >> desc->offset) & desc->mask;
	return parent_rate / div;
}

static long clk_corediv_round_rate(struct clk_hw *hwclk, unsigned long rate,
			       unsigned long *parent_rate)
{
	/* Valid ratio are 1:4, 1:5, 1:6 and 1:8 */
	u32 div;

	div = *parent_rate / rate;
	if (div < 4)
		div = 4;
	else if (div > 6)
		div = 8;

	return *parent_rate / div;
}

static int clk_corediv_set_rate(struct clk_hw *hwclk, unsigned long rate,
			    unsigned long parent_rate)
{
	struct clk_corediv *corediv = to_corediv_clk(hwclk);
	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
	const struct clk_corediv_desc *desc = corediv->desc;
	unsigned long flags = 0;
	u32 reg, div;

	div = parent_rate / rate;

	spin_lock_irqsave(&corediv->lock, flags);

	/* Write new divider to the divider ratio register */
	reg = readl(corediv->reg + soc_desc->ratio_offset);
	reg &= ~(desc->mask << desc->offset);
	reg |= (div & desc->mask) << desc->offset;
	writel(reg, corediv->reg + soc_desc->ratio_offset);

	/* Set reload-force for this clock */
	reg = readl(corediv->reg) | BIT(desc->fieldbit);
	writel(reg, corediv->reg);

	/* Now trigger the clock update */
	reg = readl(corediv->reg) | soc_desc->ratio_reload;
	writel(reg, corediv->reg);

	/*
	 * Wait for clocks to settle down, and then clear all the
	 * ratios request and the reload request.
	 */
	udelay(1000);
	reg &= ~(CORE_CLK_DIV_RATIO_MASK | soc_desc->ratio_reload);
	writel(reg, corediv->reg);
	udelay(1000);

	spin_unlock_irqrestore(&corediv->lock, flags);

	return 0;
}

static const struct clk_corediv_soc_desc armada370_corediv_soc = {
	.descs = mvebu_corediv_desc,
	.ndescs = ARRAY_SIZE(mvebu_corediv_desc),
	.ops = {
		.enable = clk_corediv_enable,
		.disable = clk_corediv_disable,
		.is_enabled = clk_corediv_is_enabled,
		.recalc_rate = clk_corediv_recalc_rate,
		.round_rate = clk_corediv_round_rate,
		.set_rate = clk_corediv_set_rate,
	},
	.ratio_reload = BIT(8),
	.enable_bit_offset = 24,
	.ratio_offset = 0x8,
};

static void __init
mvebu_corediv_clk_init(struct device_node *node,
		       const struct clk_corediv_soc_desc *soc_desc)
{
	struct clk_init_data init;
	struct clk_corediv *corediv;
	struct clk **clks;
	void __iomem *base;
	const char *parent_name;
	const char *clk_name;
	int i;

	base = of_iomap(node, 0);
	if (WARN_ON(!base))
		return;

	parent_name = of_clk_get_parent_name(node, 0);

	clk_data.clk_num = soc_desc->ndescs;

	/* clks holds the clock array */
	clks = kcalloc(clk_data.clk_num, sizeof(struct clk *),
				GFP_KERNEL);
	if (WARN_ON(!clks))
		goto err_unmap;
	/* corediv holds the clock specific array */
	corediv = kcalloc(clk_data.clk_num, sizeof(struct clk_corediv),
				GFP_KERNEL);
	if (WARN_ON(!corediv))
		goto err_free_clks;

	spin_lock_init(&corediv->lock);

	for (i = 0; i < clk_data.clk_num; i++) {
		of_property_read_string_index(node, "clock-output-names",
					      i, &clk_name);
		init.num_parents = 1;
		init.parent_names = &parent_name;
		init.name = clk_name;
		init.ops = &soc_desc->ops;
		init.flags = 0;

		corediv[i].soc_desc = soc_desc;
		corediv[i].desc = soc_desc->descs + i;
		corediv[i].reg = base;
		corediv[i].hw.init = &init;

		clks[i] = clk_register(NULL, &corediv[i].hw);
		WARN_ON(IS_ERR(clks[i]));
	}

	clk_data.clks = clks;
	of_clk_add_provider(node, of_clk_src_onecell_get, &clk_data);
	return;

err_free_clks:
	kfree(clks);
err_unmap:
	iounmap(base);
}

static void __init armada370_corediv_clk_init(struct device_node *node)
{
	return mvebu_corediv_clk_init(node, &armada370_corediv_soc);
}
CLK_OF_DECLARE(armada370_corediv_clk, "marvell,armada-370-corediv-clock",
	       armada370_corediv_clk_init);