/*
 * Copyright (c) 2015, The Linux Foundation. All rights reserved.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/clk-provider.h>
#include <linux/regmap.h>
#include <linux/delay.h>

#include "clk-alpha-pll.h"

#define PLL_MODE		0x00
# define PLL_OUTCTRL		BIT(0)
# define PLL_BYPASSNL		BIT(1)
# define PLL_RESET_N		BIT(2)
# define PLL_LOCK_COUNT_SHIFT	8
# define PLL_LOCK_COUNT_MASK	0x3f
# define PLL_BIAS_COUNT_SHIFT	14
# define PLL_BIAS_COUNT_MASK	0x3f
# define PLL_VOTE_FSM_ENA	BIT(20)
# define PLL_VOTE_FSM_RESET	BIT(21)
# define PLL_ACTIVE_FLAG	BIT(30)
# define PLL_LOCK_DET		BIT(31)

#define PLL_L_VAL		0x04
#define PLL_ALPHA_VAL		0x08
#define PLL_ALPHA_VAL_U		0x0c

#define PLL_USER_CTL		0x10
# define PLL_POST_DIV_SHIFT	8
# define PLL_POST_DIV_MASK	0xf
# define PLL_ALPHA_EN		BIT(24)
# define PLL_VCO_SHIFT		20
# define PLL_VCO_MASK		0x3

#define PLL_USER_CTL_U		0x14

#define PLL_CONFIG_CTL		0x18
#define PLL_TEST_CTL		0x1c
#define PLL_TEST_CTL_U		0x20
#define PLL_STATUS		0x24

/*
 * Even though 40 bits are present, use only 32 for ease of calculation.
 */
#define ALPHA_REG_BITWIDTH	40
#define ALPHA_BITWIDTH		32

#define to_clk_alpha_pll(_hw) container_of(to_clk_regmap(_hw), \
					   struct clk_alpha_pll, clkr)

#define to_clk_alpha_pll_postdiv(_hw) container_of(to_clk_regmap(_hw), \
					   struct clk_alpha_pll_postdiv, clkr)

static int wait_for_pll(struct clk_alpha_pll *pll)
{
	u32 val, mask, off;
	int count;
	int ret;
	const char *name = clk_hw_get_name(&pll->clkr.hw);

	off = pll->offset;
	ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &val);
	if (ret)
		return ret;

	if (val & PLL_VOTE_FSM_ENA)
		mask = PLL_ACTIVE_FLAG;
	else
		mask = PLL_LOCK_DET;

	/* Wait for pll to enable. */
	for (count = 100; count > 0; count--) {
		ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &val);
		if (ret)
			return ret;
		if ((val & mask) == mask)
			return 0;

		udelay(1);
	}

	WARN(1, "%s didn't enable after voting for it!\n", name);
	return -ETIMEDOUT;
}

static int clk_alpha_pll_enable(struct clk_hw *hw)
{
	int ret;
	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
	u32 val, mask, off;

	off = pll->offset;

	mask = PLL_OUTCTRL | PLL_RESET_N | PLL_BYPASSNL;
	ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &val);
	if (ret)
		return ret;

	/* If in FSM mode, just vote for it */
	if (val & PLL_VOTE_FSM_ENA) {
		ret = clk_enable_regmap(hw);
		if (ret)
			return ret;
		return wait_for_pll(pll);
	}

	/* Skip if already enabled */
	if ((val & mask) == mask)
		return 0;

	ret = regmap_update_bits(pll->clkr.regmap, off + PLL_MODE,
				 PLL_BYPASSNL, PLL_BYPASSNL);
	if (ret)
		return ret;

	/*
	 * H/W requires a 5us delay between disabling the bypass and
	 * de-asserting the reset.
	 */
	mb();
	udelay(5);

	ret = regmap_update_bits(pll->clkr.regmap, off + PLL_MODE,
				 PLL_RESET_N, PLL_RESET_N);
	if (ret)
		return ret;

	ret = wait_for_pll(pll);
	if (ret)
		return ret;

	ret = regmap_update_bits(pll->clkr.regmap, off + PLL_MODE,
				 PLL_OUTCTRL, PLL_OUTCTRL);

	/* Ensure that the write above goes through before returning. */
	mb();
	return ret;
}

static void clk_alpha_pll_disable(struct clk_hw *hw)
{
	int ret;
	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
	u32 val, mask, off;

	off = pll->offset;

	ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &val);
	if (ret)
		return;

	/* If in FSM mode, just unvote it */
	if (val & PLL_VOTE_FSM_ENA) {
		clk_disable_regmap(hw);
		return;
	}

	mask = PLL_OUTCTRL;
	regmap_update_bits(pll->clkr.regmap, off + PLL_MODE, mask, 0);

	/* Delay of 2 output clock ticks required until output is disabled */
	mb();
	udelay(1);

	mask = PLL_RESET_N | PLL_BYPASSNL;
	regmap_update_bits(pll->clkr.regmap, off + PLL_MODE, mask, 0);
}

static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
{
	return (prate * l) + ((prate * a) >> ALPHA_BITWIDTH);
}

static unsigned long
alpha_pll_round_rate(unsigned long rate, unsigned long prate, u32 *l, u64 *a)
{
	u64 remainder;
	u64 quotient;

	quotient = rate;
	remainder = do_div(quotient, prate);
	*l = quotient;

	if (!remainder) {
		*a = 0;
		return rate;
	}

	/* Upper ALPHA_BITWIDTH bits of Alpha */
	quotient = remainder << ALPHA_BITWIDTH;
	remainder = do_div(quotient, prate);

	if (remainder)
		quotient++;

	*a = quotient;
	return alpha_pll_calc_rate(prate, *l, *a);
}

static const struct pll_vco *
alpha_pll_find_vco(const struct clk_alpha_pll *pll, unsigned long rate)
{
	const struct pll_vco *v = pll->vco_table;
	const struct pll_vco *end = v + pll->num_vco;

	for (; v < end; v++)
		if (rate >= v->min_freq && rate <= v->max_freq)
			return v;

	return NULL;
}

static unsigned long
clk_alpha_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
{
	u32 l, low, high, ctl;
	u64 a = 0, prate = parent_rate;
	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
	u32 off = pll->offset;

	regmap_read(pll->clkr.regmap, off + PLL_L_VAL, &l);

	regmap_read(pll->clkr.regmap, off + PLL_USER_CTL, &ctl);
	if (ctl & PLL_ALPHA_EN) {
		regmap_read(pll->clkr.regmap, off + PLL_ALPHA_VAL, &low);
		regmap_read(pll->clkr.regmap, off + PLL_ALPHA_VAL_U, &high);
		a = (u64)high << 32 | low;
		a >>= ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH;
	}

	return alpha_pll_calc_rate(prate, l, a);
}

static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
				  unsigned long prate)
{
	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
	const struct pll_vco *vco;
	u32 l, off = pll->offset;
	u64 a;

	rate = alpha_pll_round_rate(rate, prate, &l, &a);
	vco = alpha_pll_find_vco(pll, rate);
	if (!vco) {
		pr_err("alpha pll not in a valid vco range\n");
		return -EINVAL;
	}

	a <<= (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);

	regmap_write(pll->clkr.regmap, off + PLL_L_VAL, l);
	regmap_write(pll->clkr.regmap, off + PLL_ALPHA_VAL, a);
	regmap_write(pll->clkr.regmap, off + PLL_ALPHA_VAL_U, a >> 32);

	regmap_update_bits(pll->clkr.regmap, off + PLL_USER_CTL,
			   PLL_VCO_MASK << PLL_VCO_SHIFT,
			   vco->val << PLL_VCO_SHIFT);

	regmap_update_bits(pll->clkr.regmap, off + PLL_USER_CTL, PLL_ALPHA_EN,
			   PLL_ALPHA_EN);

	return 0;
}

static long clk_alpha_pll_round_rate(struct clk_hw *hw, unsigned long rate,
				     unsigned long *prate)
{
	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
	u32 l;
	u64 a;
	unsigned long min_freq, max_freq;

	rate = alpha_pll_round_rate(rate, *prate, &l, &a);
	if (alpha_pll_find_vco(pll, rate))
		return rate;

	min_freq = pll->vco_table[0].min_freq;
	max_freq = pll->vco_table[pll->num_vco - 1].max_freq;

	return clamp(rate, min_freq, max_freq);
}

const struct clk_ops clk_alpha_pll_ops = {
	.enable = clk_alpha_pll_enable,
	.disable = clk_alpha_pll_disable,
	.recalc_rate = clk_alpha_pll_recalc_rate,
	.round_rate = clk_alpha_pll_round_rate,
	.set_rate = clk_alpha_pll_set_rate,
};
EXPORT_SYMBOL_GPL(clk_alpha_pll_ops);

static unsigned long
clk_alpha_pll_postdiv_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
{
	struct clk_alpha_pll_postdiv *pll = to_clk_alpha_pll_postdiv(hw);
	u32 ctl;

	regmap_read(pll->clkr.regmap, pll->offset + PLL_USER_CTL, &ctl);

	ctl >>= PLL_POST_DIV_SHIFT;
	ctl &= PLL_POST_DIV_MASK;

	return parent_rate >> fls(ctl);
}

static const struct clk_div_table clk_alpha_div_table[] = {
	{ 0x0, 1 },
	{ 0x1, 2 },
	{ 0x3, 4 },
	{ 0x7, 8 },
	{ 0xf, 16 },
	{ }
};

static long
clk_alpha_pll_postdiv_round_rate(struct clk_hw *hw, unsigned long rate,
				 unsigned long *prate)
{
	struct clk_alpha_pll_postdiv *pll = to_clk_alpha_pll_postdiv(hw);

	return divider_round_rate(hw, rate, prate, clk_alpha_div_table,
				  pll->width, CLK_DIVIDER_POWER_OF_TWO);
}

static int clk_alpha_pll_postdiv_set_rate(struct clk_hw *hw, unsigned long rate,
					  unsigned long parent_rate)
{
	struct clk_alpha_pll_postdiv *pll = to_clk_alpha_pll_postdiv(hw);
	int div;

	/* 16 -> 0xf, 8 -> 0x7, 4 -> 0x3, 2 -> 0x1, 1 -> 0x0 */
	div = DIV_ROUND_UP_ULL((u64)parent_rate, rate) - 1;

	return regmap_update_bits(pll->clkr.regmap, pll->offset + PLL_USER_CTL,
				  PLL_POST_DIV_MASK << PLL_POST_DIV_SHIFT,
				  div << PLL_POST_DIV_SHIFT);
}

const struct clk_ops clk_alpha_pll_postdiv_ops = {
	.recalc_rate = clk_alpha_pll_postdiv_recalc_rate,
	.round_rate = clk_alpha_pll_postdiv_round_rate,
	.set_rate = clk_alpha_pll_postdiv_set_rate,
};
EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_ops);