/*
 *  Cirrus Logic CLPS711X CLK driver
 *
 *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/mfd/syscon/clps711x.h>

#include <dt-bindings/clock/clps711x-clock.h>

#define CLPS711X_SYSCON1	(0x0100)
#define CLPS711X_SYSCON2	(0x1100)
#define CLPS711X_SYSFLG2	(CLPS711X_SYSCON2 + SYSFLG_OFFSET)
#define CLPS711X_PLLR		(0xa5a8)

#define CLPS711X_EXT_FREQ	(13000000)
#define CLPS711X_OSC_FREQ	(3686400)

static const struct clk_div_table spi_div_table[] = {
	{ .val = 0, .div = 32, },
	{ .val = 1, .div = 8, },
	{ .val = 2, .div = 2, },
	{ .val = 3, .div = 1, },
};

static const struct clk_div_table timer_div_table[] = {
	{ .val = 0, .div = 256, },
	{ .val = 1, .div = 1, },
};

struct clps711x_clk {
	struct clk_onecell_data	clk_data;
	spinlock_t		lock;
	struct clk		*clks[CLPS711X_CLK_MAX];
};

static struct clps711x_clk * __init _clps711x_clk_init(void __iomem *base,
						       u32 fref)
{
	u32 tmp, f_cpu, f_pll, f_bus, f_tim, f_pwm, f_spi;
	struct clps711x_clk *clps711x_clk;
	unsigned i;

	if (!base)
		return ERR_PTR(-ENOMEM);

	clps711x_clk = kzalloc(sizeof(*clps711x_clk), GFP_KERNEL);
	if (!clps711x_clk)
		return ERR_PTR(-ENOMEM);

	spin_lock_init(&clps711x_clk->lock);

	/* Read PLL multiplier value and sanity check */
	tmp = readl(base + CLPS711X_PLLR) >> 24;
	if (((tmp >= 10) && (tmp <= 50)) || !fref)
		f_pll = DIV_ROUND_UP(CLPS711X_OSC_FREQ * tmp, 2);
	else
		f_pll = fref;

	tmp = readl(base + CLPS711X_SYSFLG2);
	if (tmp & SYSFLG2_CKMODE) {
		f_cpu = CLPS711X_EXT_FREQ;
		f_bus = CLPS711X_EXT_FREQ;
		f_spi = DIV_ROUND_CLOSEST(CLPS711X_EXT_FREQ, 96);
		f_pll = 0;
		f_pwm = DIV_ROUND_CLOSEST(CLPS711X_EXT_FREQ, 128);
	} else {
		f_cpu = f_pll;
		if (f_cpu > 36864000)
			f_bus = DIV_ROUND_UP(f_cpu, 2);
		else
			f_bus = 36864000 / 2;
		f_spi = DIV_ROUND_CLOSEST(f_cpu, 576);
		f_pwm = DIV_ROUND_CLOSEST(f_cpu, 768);
	}

	if (tmp & SYSFLG2_CKMODE) {
		if (readl(base + CLPS711X_SYSCON2) & SYSCON2_OSTB)
			f_tim = DIV_ROUND_CLOSEST(CLPS711X_EXT_FREQ, 26);
		else
			f_tim = DIV_ROUND_CLOSEST(CLPS711X_EXT_FREQ, 24);
	} else
		f_tim = DIV_ROUND_CLOSEST(f_cpu, 144);

	tmp = readl(base + CLPS711X_SYSCON1);
	/* Timer1 in free running mode.
	 * Counter will wrap around to 0xffff when it underflows
	 * and will continue to count down.
	 */
	tmp &= ~(SYSCON1_TC1M | SYSCON1_TC1S);
	/* Timer2 in prescale mode.
	 * Value writen is automatically re-loaded when
	 * the counter underflows.
	 */
	tmp |= SYSCON1_TC2M | SYSCON1_TC2S;
	writel(tmp, base + CLPS711X_SYSCON1);

	clps711x_clk->clks[CLPS711X_CLK_DUMMY] =
		clk_register_fixed_rate(NULL, "dummy", NULL, CLK_IS_ROOT, 0);
	clps711x_clk->clks[CLPS711X_CLK_CPU] =
		clk_register_fixed_rate(NULL, "cpu", NULL, CLK_IS_ROOT, f_cpu);
	clps711x_clk->clks[CLPS711X_CLK_BUS] =
		clk_register_fixed_rate(NULL, "bus", NULL, CLK_IS_ROOT, f_bus);
	clps711x_clk->clks[CLPS711X_CLK_PLL] =
		clk_register_fixed_rate(NULL, "pll", NULL, CLK_IS_ROOT, f_pll);
	clps711x_clk->clks[CLPS711X_CLK_TIMERREF] =
		clk_register_fixed_rate(NULL, "timer_ref", NULL, CLK_IS_ROOT,
					f_tim);
	clps711x_clk->clks[CLPS711X_CLK_TIMER1] =
		clk_register_divider_table(NULL, "timer1", "timer_ref", 0,
					   base + CLPS711X_SYSCON1, 5, 1, 0,
					   timer_div_table, &clps711x_clk->lock);
	clps711x_clk->clks[CLPS711X_CLK_TIMER2] =
		clk_register_divider_table(NULL, "timer2", "timer_ref", 0,
					   base + CLPS711X_SYSCON1, 7, 1, 0,
					   timer_div_table, &clps711x_clk->lock);
	clps711x_clk->clks[CLPS711X_CLK_PWM] =
		clk_register_fixed_rate(NULL, "pwm", NULL, CLK_IS_ROOT, f_pwm);
	clps711x_clk->clks[CLPS711X_CLK_SPIREF] =
		clk_register_fixed_rate(NULL, "spi_ref", NULL, CLK_IS_ROOT,
					f_spi);
	clps711x_clk->clks[CLPS711X_CLK_SPI] =
		clk_register_divider_table(NULL, "spi", "spi_ref", 0,
					   base + CLPS711X_SYSCON1, 16, 2, 0,
					   spi_div_table, &clps711x_clk->lock);
	clps711x_clk->clks[CLPS711X_CLK_UART] =
		clk_register_fixed_factor(NULL, "uart", "bus", 0, 1, 10);
	clps711x_clk->clks[CLPS711X_CLK_TICK] =
		clk_register_fixed_rate(NULL, "tick", NULL, CLK_IS_ROOT, 64);

	for (i = 0; i < CLPS711X_CLK_MAX; i++)
		if (IS_ERR(clps711x_clk->clks[i]))
			pr_err("clk %i: register failed with %ld\n",
			       i, PTR_ERR(clps711x_clk->clks[i]));

	return clps711x_clk;
}

void __init clps711x_clk_init(void __iomem *base)
{
	struct clps711x_clk *clps711x_clk;

	clps711x_clk = _clps711x_clk_init(base, 73728000);

	BUG_ON(IS_ERR(clps711x_clk));

	/* Clocksource */
	clk_register_clkdev(clps711x_clk->clks[CLPS711X_CLK_TIMER1],
			    NULL, "clps711x-timer.0");
	clk_register_clkdev(clps711x_clk->clks[CLPS711X_CLK_TIMER2],
			    NULL, "clps711x-timer.1");

	/* Drivers */
	clk_register_clkdev(clps711x_clk->clks[CLPS711X_CLK_PWM],
			    NULL, "clps711x-pwm");
	clk_register_clkdev(clps711x_clk->clks[CLPS711X_CLK_UART],
			    NULL, "clps711x-uart.0");
	clk_register_clkdev(clps711x_clk->clks[CLPS711X_CLK_UART],
			    NULL, "clps711x-uart.1");
}

#ifdef CONFIG_OF
static void __init clps711x_clk_init_dt(struct device_node *np)
{
	void __iomem *base = of_iomap(np, 0);
	struct clps711x_clk *clps711x_clk;
	u32 fref = 0;

	WARN_ON(of_property_read_u32(np, "startup-frequency", &fref));

	clps711x_clk = _clps711x_clk_init(base, fref);
	BUG_ON(IS_ERR(clps711x_clk));

	clps711x_clk->clk_data.clks = clps711x_clk->clks;
	clps711x_clk->clk_data.clk_num = CLPS711X_CLK_MAX;
	of_clk_add_provider(np, of_clk_src_onecell_get,
			    &clps711x_clk->clk_data);
}
CLK_OF_DECLARE(clps711x, "cirrus,clps711x-clk", clps711x_clk_init_dt);
#endif