/* linux/arch/arm/plat-s3c24xx/pwm-clock.c
 *
 * Copyright (c) 2007 Simtec Electronics
 * Copyright (c) 2007, 2008 Ben Dooks
 *	Ben Dooks <ben-linux@fluff.org>
 *
 * 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.
*/

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/log2.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <mach/map.h>
#include <asm/irq.h>

#include <plat/clock.h>
#include <plat/cpu.h>

#include <plat/regs-timer.h>
#include <plat/pwm-clock.h>

/* Each of the timers 0 through 5 go through the following
 * clock tree, with the inputs depending on the timers.
 *
 * pclk ---- [ prescaler 0 ] -+---> timer 0
 *			      +---> timer 1
 *
 * pclk ---- [ prescaler 1 ] -+---> timer 2
 *			      +---> timer 3
 *			      \---> timer 4
 *
 * Which are fed into the timers as so:
 *
 * prescaled 0 ---- [ div 2,4,8,16 ] ---\
 *				       [mux] -> timer 0
 * tclk 0 ------------------------------/
 *
 * prescaled 0 ---- [ div 2,4,8,16 ] ---\
 *				       [mux] -> timer 1
 * tclk 0 ------------------------------/
 *
 *
 * prescaled 1 ---- [ div 2,4,8,16 ] ---\
 *				       [mux] -> timer 2
 * tclk 1 ------------------------------/
 *
 * prescaled 1 ---- [ div 2,4,8,16 ] ---\
 *				       [mux] -> timer 3
 * tclk 1 ------------------------------/
 *
 * prescaled 1 ---- [ div 2,4,8, 16 ] --\
 *				       [mux] -> timer 4
 * tclk 1 ------------------------------/
 *
 * Since the mux and the divider are tied together in the
 * same register space, it is impossible to set the parent
 * and the rate at the same time. To avoid this, we add an
 * intermediate 'prescaled-and-divided' clock to select
 * as the parent for the timer input clock called tdiv.
 *
 * prescaled clk --> pwm-tdiv ---\
 *                             [ mux ] --> timer X
 * tclk -------------------------/
*/

static struct clk clk_timer_scaler[];

static unsigned long clk_pwm_scaler_get_rate(struct clk *clk)
{
	unsigned long tcfg0 = __raw_readl(S3C2410_TCFG0);

	if (clk == &clk_timer_scaler[1]) {
		tcfg0 &= S3C2410_TCFG_PRESCALER1_MASK;
		tcfg0 >>= S3C2410_TCFG_PRESCALER1_SHIFT;
	} else {
		tcfg0 &= S3C2410_TCFG_PRESCALER0_MASK;
	}

	return clk_get_rate(clk->parent) / (tcfg0 + 1);
}

static unsigned long clk_pwm_scaler_round_rate(struct clk *clk,
					       unsigned long rate)
{
	unsigned long parent_rate = clk_get_rate(clk->parent);
	unsigned long divisor = parent_rate / rate;

	if (divisor > 256)
		divisor = 256;
	else if (divisor < 2)
		divisor = 2;

	return parent_rate / divisor;
}

static int clk_pwm_scaler_set_rate(struct clk *clk, unsigned long rate)
{
	unsigned long round = clk_pwm_scaler_round_rate(clk, rate);
	unsigned long tcfg0;
	unsigned long divisor;
	unsigned long flags;

	divisor = clk_get_rate(clk->parent) / round;
	divisor--;

	local_irq_save(flags);
	tcfg0 = __raw_readl(S3C2410_TCFG0);

	if (clk == &clk_timer_scaler[1]) {
		tcfg0 &= ~S3C2410_TCFG_PRESCALER1_MASK;
		tcfg0 |= divisor << S3C2410_TCFG_PRESCALER1_SHIFT;
	} else {
		tcfg0 &= ~S3C2410_TCFG_PRESCALER0_MASK;
		tcfg0 |= divisor;
	}

	__raw_writel(tcfg0, S3C2410_TCFG0);
	local_irq_restore(flags);

	return 0;
}

static struct clk_ops clk_pwm_scaler_ops = {
	.get_rate	= clk_pwm_scaler_get_rate,
	.set_rate	= clk_pwm_scaler_set_rate,
	.round_rate	= clk_pwm_scaler_round_rate,
};

static struct clk clk_timer_scaler[] = {
	[0]	= {
		.name		= "pwm-scaler0",
		.id		= -1,
		.ops		= &clk_pwm_scaler_ops,
	},
	[1]	= {
		.name		= "pwm-scaler1",
		.id		= -1,
		.ops		= &clk_pwm_scaler_ops,
	},
};

static struct clk clk_timer_tclk[] = {
	[0]	= {
		.name		= "pwm-tclk0",
		.id		= -1,
	},
	[1]	= {
		.name		= "pwm-tclk1",
		.id		= -1,
	},
};

struct pwm_tdiv_clk {
	struct clk	clk;
	unsigned int	divisor;
};

static inline struct pwm_tdiv_clk *to_tdiv(struct clk *clk)
{
	return container_of(clk, struct pwm_tdiv_clk, clk);
}

static unsigned long clk_pwm_tdiv_get_rate(struct clk *clk)
{
	unsigned long tcfg1 = __raw_readl(S3C2410_TCFG1);
	unsigned int divisor;

	tcfg1 >>= S3C2410_TCFG1_SHIFT(clk->id);
	tcfg1 &= S3C2410_TCFG1_MUX_MASK;

	if (pwm_cfg_src_is_tclk(tcfg1))
		divisor = to_tdiv(clk)->divisor;
	else
		divisor = tcfg_to_divisor(tcfg1);

	return clk_get_rate(clk->parent) / divisor;
}

static unsigned long clk_pwm_tdiv_round_rate(struct clk *clk,
					     unsigned long rate)
{
	unsigned long parent_rate;
	unsigned long divisor;

	parent_rate = clk_get_rate(clk->parent);
	divisor = parent_rate / rate;

	if (divisor <= 1 && pwm_tdiv_has_div1())
		divisor = 1;
	else if (divisor <= 2)
		divisor = 2;
	else if (divisor <= 4)
		divisor = 4;
	else if (divisor <= 8)
		divisor = 8;
	else
		divisor = 16;

	return parent_rate / divisor;
}

static unsigned long clk_pwm_tdiv_bits(struct pwm_tdiv_clk *divclk)