drivers/clocksource/samsung_pwm_timer.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2011 Samsung Electronics Co., Ltd.
  *		http://www.samsung.com/
  *
  * samsung - Common hr-timer support (s3c and s5p)
  *
  * 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/interrupt.h>
 #include <linux/irq.h>
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/clockchips.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>

 #include <clocksource/samsung_pwm.h>

 #include <asm/sched_clock.h>

 /*
  * Clocksource driver
  */

 #define REG_TCFG0			0x00
 #define REG_TCFG1			0x04
 #define REG_TCON			0x08
 #define REG_TINT_CSTAT			0x44

 #define REG_TCNTB(chan)			(0x0c + 12 * (chan))
 #define REG_TCMPB(chan)			(0x10 + 12 * (chan))

 #define TCFG0_PRESCALER_MASK		0xff
 #define TCFG0_PRESCALER1_SHIFT		8

 #define TCFG1_SHIFT(x)	  		((x) * 4)
 #define TCFG1_MUX_MASK	  		0xf

 #define TCON_START(chan)		(1 << (4 * (chan) + 0))
 #define TCON_MANUALUPDATE(chan)		(1 << (4 * (chan) + 1))
 #define TCON_INVERT(chan)		(1 << (4 * (chan) + 2))
 #define TCON_AUTORELOAD(chan)		(1 << (4 * (chan) + 3))

 DEFINE_SPINLOCK(samsung_pwm_lock);
 EXPORT_SYMBOL(samsung_pwm_lock);

 struct samsung_pwm_clocksource {
 	void __iomem *base;
 	unsigned int irq[SAMSUNG_PWM_NUM];
 	struct samsung_pwm_variant variant;

 	struct clk *timerclk;

 	unsigned int event_id;
 	unsigned int source_id;
 	unsigned int tcnt_max;
 	unsigned int tscaler_div;
 	unsigned int tdiv;

 	unsigned long clock_count_per_tick;
 };

 static struct samsung_pwm_clocksource pwm;

 static void samsung_timer_set_prescale(unsigned int channel, u16 prescale)
 {
 	unsigned long flags;
 	u8 shift = 0;
 	u32 reg;

 	if (channel >= 2)
 		shift = TCFG0_PRESCALER1_SHIFT;

 	spin_lock_irqsave(&samsung_pwm_lock, flags);

 	reg = readl(pwm.base + REG_TCFG0);
 	reg &= ~(TCFG0_PRESCALER_MASK << shift);
 	reg |= (prescale - 1) << shift;
 	writel(reg, pwm.base + REG_TCFG0);

 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }

 static void samsung_timer_set_divisor(unsigned int channel, u8 divisor)
 {
 	u8 shift = TCFG1_SHIFT(channel);
 	unsigned long flags;
 	u32 reg;
 	u8 bits;

 	bits = (fls(divisor) - 1) - pwm.variant.div_base;

 	spin_lock_irqsave(&samsung_pwm_lock, flags);

 	reg = readl(pwm.base + REG_TCFG1);
 	reg &= ~(TCFG1_MUX_MASK << shift);
 	reg |= bits << shift;
 	writel(reg, pwm.base + REG_TCFG1);

 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }

 static void samsung_time_stop(unsigned int channel)
 {
 	unsigned long tcon;
 	unsigned long flags;

 	if (channel > 0)
 		++channel;

 	spin_lock_irqsave(&samsung_pwm_lock, flags);

 	tcon = __raw_readl(pwm.base + REG_TCON);
 	tcon &= ~TCON_START(channel);
 	__raw_writel(tcon, pwm.base + REG_TCON);

 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }

 static void samsung_time_setup(unsigned int channel, unsigned long tcnt)
 {
 	unsigned long tcon;
 	unsigned long flags;
 	unsigned int tcon_chan = channel;

 	if (tcon_chan > 0)
 		++tcon_chan;

 	spin_lock_irqsave(&samsung_pwm_lock, flags);

 	tcon = __raw_readl(pwm.base + REG_TCON);

 	tcnt--;

 	tcon &= ~(TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan));
 	tcon |= TCON_MANUALUPDATE(tcon_chan);

 	__raw_writel(tcnt, pwm.base + REG_TCNTB(channel));
 	__raw_writel(tcnt, pwm.base + REG_TCMPB(channel));
 	__raw_writel(tcon, pwm.base + REG_TCON);

 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }

 static void samsung_time_start(unsigned int channel, bool periodic)
 {
 	unsigned long tcon;
 	unsigned long flags;

 	if (channel > 0)
 		++channel;

 	spin_lock_irqsave(&samsung_pwm_lock, flags);

 	tcon = __raw_readl(pwm.base + REG_TCON);

 	tcon &= ~TCON_MANUALUPDATE(channel);
 	tcon |= TCON_START(channel);

 	if (periodic)
 		tcon |= TCON_AUTORELOAD(channel);
 	else
 		tcon &= ~TCON_AUTORELOAD(channel);

 	__raw_writel(tcon, pwm.base + REG_TCON);

 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }

 static int samsung_set_next_event(unsigned long cycles,
 				struct clock_event_device *evt)
 {
 	samsung_time_setup(pwm.event_id, cycles);
 	samsung_time_start(pwm.event_id, false);

 	return 0;
 }

 static void samsung_timer_resume(void)
 {
 	/* event timer restart */
 	samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick);
 	samsung_time_start(pwm.event_id, true);

 	/* source timer restart */
 	samsung_time_setup(pwm.source_id, pwm.tcnt_max);
 	samsung_time_start(pwm.source_id, true);
 }

 static void samsung_set_mode(enum clock_event_mode mode,
 				struct clock_event_device *evt)
 {
 	samsung_time_stop(pwm.event_id);

 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
 		samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick);
 		samsung_time_start(pwm.event_id, true);
 		break;

 	case CLOCK_EVT_MODE_ONESHOT:
 		break;

 	case CLOCK_EVT_MODE_UNUSED:
 	case CLOCK_EVT_MODE_SHUTDOWN:
 		break;

 	case CLOCK_EVT_MODE_RESUME:
 		samsung_timer_resume();
 		break;
 	}
 }

 static struct clock_event_device time_event_device = {
 	.name		= "samsung_event_timer",
 	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 	.rating		= 200,
 	.set_next_event	= samsung_set_next_event,
 	.set_mode	= samsung_set_mode,
 };

 static irqreturn_t samsung_clock_event_isr(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = dev_id;

 	if (pwm.variant.has_tint_cstat) {
 		u32 mask = (1 << pwm.event_id);
 		writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
 	}

 	evt->event_handler(evt);

 	return IRQ_HANDLED;
 }

 static struct irqaction samsung_clock_event_irq = {
 	.name		= "samsung_time_irq",
 	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 	.handler	= samsung_clock_event_isr,
 	.dev_id		= &time_event_device,
 };

 static void __init samsung_clockevent_init(void)
 {
 	unsigned long pclk;
 	unsigned long clock_rate;
 	unsigned int irq_number;

 	pclk = clk_get_rate(pwm.timerclk);

 	samsung_timer_set_prescale(pwm.event_id, pwm.tscaler_div);
 	samsung_timer_set_divisor(pwm.event_id, pwm.tdiv);

 	clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
 	pwm.clock_count_per_tick = clock_rate / HZ;

 	time_event_device.cpumask = cpumask_of(0);
 	clockevents_config_and_register(&time_event_device, clock_rate, 1, -1);

 	irq_number = pwm.irq[pwm.event_id];
 	setup_irq(irq_number, &samsung_clock_event_irq);

 	if (pwm.variant.has_tint_cstat) {
 		u32 mask = (1 << pwm.event_id);
 		writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
 	}
 }

 static void __iomem *samsung_timer_reg(void)
 {
 	switch (pwm.source_id) {
 	case 0:
 	case 1:
 	case 2:
 	case 3:
 		return pwm.base + pwm.source_id * 0x0c + 0x14;

 	case 4:
 		return pwm.base + 0x40;

 	default:
 		BUG();
 	}
 }

 /*
  * Override the global weak sched_clock symbol with this
  * local implementation which uses the clocksource to get some
  * better resolution when scheduling the kernel. We accept that
  * this wraps around for now, since it is just a relative time
  * stamp. (Inspired by U300 implementation.)
  */
 static u32 notrace samsung_read_sched_clock(void)
 {
 	void __iomem *reg = samsung_timer_reg();

 	if (!reg)
 		return 0;

 	return ~__raw_readl(reg);
 }

 static void __init samsung_clocksource_init(void)
 {
 	void __iomem *reg = samsung_timer_reg();
 	unsigned long pclk;
 	unsigned long clock_rate;
 	int ret;

 	pclk = clk_get_rate(pwm.timerclk);

 	samsung_timer_set_prescale(pwm.source_id, pwm.tscaler_div);
 	samsung_timer_set_divisor(pwm.source_id, pwm.tdiv);

 	clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);

 	samsung_time_setup(pwm.source_id, pwm.tcnt_max);
 	samsung_time_start(pwm.source_id, true);

 	setup_sched_clock(samsung_read_sched_clock,
 						pwm.variant.bits, clock_rate);

 	ret = clocksource_mmio_init(reg, "samsung_clocksource_timer",
 					clock_rate, 250, pwm.variant.bits,
 					clocksource_mmio_readl_down);
 	if (ret)
 		panic("samsung_clocksource_timer: can't register clocksource\n");
 }

 static void __init samsung_timer_resources(void)
 {
 	pwm.timerclk = clk_get(NULL, "timers");
 	if (IS_ERR(pwm.timerclk))
 		panic("failed to get timers clock for timer");

 	clk_prepare_enable(pwm.timerclk);

 	pwm.tcnt_max = (1UL << pwm.variant.bits) - 1;
 	if (pwm.variant.bits == 16) {
 		pwm.tscaler_div = 25;
 		pwm.tdiv = 2;
 	} else {
 		pwm.tscaler_div = 2;
 		pwm.tdiv = 1;
 	}
 }

 /*
  * PWM master driver
  */
 static void __init samsung_pwm_clocksource_init(void)
 {
 	u8 mask;
 	int channel;

 	mask = ~pwm.variant.output_mask & ((1 << SAMSUNG_PWM_NUM) - 1);
 	channel = fls(mask) - 1;
 	if (channel < 0)
 		panic("failed to find PWM channel for clocksource");
 	pwm.source_id = channel;

 	mask &= ~(1 << channel);
 	channel = fls(mask) - 1;
 	if (channel < 0)
 		panic("failed to find PWM channel for clock event");
 	pwm.event_id = channel;

 	samsung_timer_resources();
 	samsung_clockevent_init();
 	samsung_clocksource_init();
 }

 static void __init samsung_pwm_alloc(struct device_node *np,
 				     const struct samsung_pwm_variant *variant)
 {
 	struct resource res;
 	struct property *prop;
 	const __be32 *cur;
 	u32 val;
 	int i;

 	memcpy(&pwm.variant, variant, sizeof(pwm.variant));
 	for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
 		pwm.irq[i] = irq_of_parse_and_map(np, i);

 	of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
 		if (val >= SAMSUNG_PWM_NUM) {
 			pr_warning("%s: invalid channel index in samsung,pwm-outputs property\n",
 								__func__);
 			continue;
 		}
 		pwm.variant.output_mask |= 1 << val;
 	}

 	of_address_to_resource(np, 0, &res);
 	if (!request_mem_region(res.start,
 				resource_size(&res), "samsung-pwm")) {
 		pr_err("%s: failed to request IO mem region\n", __func__);
 		return;
 	}

 	pwm.base = ioremap(res.start, resource_size(&res));
 	if (!pwm.base) {
 		pr_err("%s: failed to map PWM registers\n", __func__);
 		release_mem_region(res.start, resource_size(&res));
 		return;
 	}

 	samsung_pwm_clocksource_init();
 }

 static const struct samsung_pwm_variant s3c24xx_variant = {
 	.bits		= 16,
 	.div_base	= 1,
 	.has_tint_cstat	= false,
 	.tclk_mask	= (1 << 4),
 };

 static void __init s3c2410_pwm_clocksource_init(struct device_node *np)
 {
 	samsung_pwm_alloc(np, &s3c24xx_variant);
 }
 CLOCKSOURCE_OF_DECLARE(s3c2410_pwm, "samsung,s3c2410-pwm", s3c2410_pwm_clocksource_init);

 static const struct samsung_pwm_variant s3c64xx_variant = {
 	.bits		= 32,
 	.div_base	= 0,
 	.has_tint_cstat	= true,
 	.tclk_mask	= (1 << 7) | (1 << 6) | (1 << 5),
 };

 static void __init s3c64xx_pwm_clocksource_init(struct device_node *np)
 {
 	samsung_pwm_alloc(np, &s3c64xx_variant);
 }
 CLOCKSOURCE_OF_DECLARE(s3c6400_pwm, "samsung,s3c6400-pwm", s3c64xx_pwm_clocksource_init);

 static const struct samsung_pwm_variant s5p64x0_variant = {
 	.bits		= 32,
 	.div_base	= 0,
 	.has_tint_cstat	= true,
 	.tclk_mask	= 0,
 };

 static void __init s5p64x0_pwm_clocksource_init(struct device_node *np)
 {
 	samsung_pwm_alloc(np, &s5p64x0_variant);
 }
 CLOCKSOURCE_OF_DECLARE(s5p6440_pwm, "samsung,s5p6440-pwm", s5p64x0_pwm_clocksource_init);

 static const struct samsung_pwm_variant s5p_variant = {
 	.bits		= 32,
 	.div_base	= 0,
 	.has_tint_cstat	= true,
 	.tclk_mask	= (1 << 5),
 };

 static void __init s5p_pwm_clocksource_init(struct device_node *np)
 {
 	samsung_pwm_alloc(np, &s5p_variant);
 }
 CLOCKSOURCE_OF_DECLARE(s5pc100_pwm, "samsung,s5pc100-pwm", s5p_pwm_clocksource_init);
	/*
	* Copyright (c) 2011 Samsung Electronics Co., Ltd.
	* http://www.samsung.com/
	*
	* samsung - Common hr-timer support (s3c and s5p)
	*
	* 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/interrupt.h>
	#include <linux/irq.h>
	#include <linux/err.h>
	#include <linux/clk.h>
	#include <linux/clockchips.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_address.h>
	#include <linux/of_irq.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>

	#include <clocksource/samsung_pwm.h>

	#include <asm/sched_clock.h>

	/*
	* Clocksource driver
	*/

	#define REG_TCFG0 0x00
	#define REG_TCFG1 0x04
	#define REG_TCON 0x08
	#define REG_TINT_CSTAT 0x44

	#define REG_TCNTB(chan) (0x0c + 12 * (chan))
	#define REG_TCMPB(chan) (0x10 + 12 * (chan))

	#define TCFG0_PRESCALER_MASK 0xff
	#define TCFG0_PRESCALER1_SHIFT 8

	#define TCFG1_SHIFT(x) ((x) * 4)
	#define TCFG1_MUX_MASK 0xf

	#define TCON_START(chan) (1 << (4 * (chan) + 0))
	#define TCON_MANUALUPDATE(chan) (1 << (4 * (chan) + 1))
	#define TCON_INVERT(chan) (1 << (4 * (chan) + 2))
	#define TCON_AUTORELOAD(chan) (1 << (4 * (chan) + 3))

	DEFINE_SPINLOCK(samsung_pwm_lock);
	EXPORT_SYMBOL(samsung_pwm_lock);

	struct samsung_pwm_clocksource {
	void __iomem *base;
	unsigned int irq[SAMSUNG_PWM_NUM];
	struct samsung_pwm_variant variant;

	struct clk *timerclk;

	unsigned int event_id;
	unsigned int source_id;
	unsigned int tcnt_max;
	unsigned int tscaler_div;
	unsigned int tdiv;

	unsigned long clock_count_per_tick;
	};

	static struct samsung_pwm_clocksource pwm;

	static void samsung_timer_set_prescale(unsigned int channel, u16 prescale)
	{
	unsigned long flags;
	u8 shift = 0;
	u32 reg;

	if (channel >= 2)
	shift = TCFG0_PRESCALER1_SHIFT;

	spin_lock_irqsave(&samsung_pwm_lock, flags);

	reg = readl(pwm.base + REG_TCFG0);
	reg &= ~(TCFG0_PRESCALER_MASK << shift);
	reg \|= (prescale - 1) << shift;
	writel(reg, pwm.base + REG_TCFG0);

	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
	}

	static void samsung_timer_set_divisor(unsigned int channel, u8 divisor)
	{
	u8 shift = TCFG1_SHIFT(channel);
	unsigned long flags;
	u32 reg;
	u8 bits;

	bits = (fls(divisor) - 1) - pwm.variant.div_base;

	spin_lock_irqsave(&samsung_pwm_lock, flags);

	reg = readl(pwm.base + REG_TCFG1);
	reg &= ~(TCFG1_MUX_MASK << shift);
	reg \|= bits << shift;
	writel(reg, pwm.base + REG_TCFG1);

	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
	}

	static void samsung_time_stop(unsigned int channel)
	{
	unsigned long tcon;
	unsigned long flags;

	if (channel > 0)
	++channel;

	spin_lock_irqsave(&samsung_pwm_lock, flags);

	tcon = __raw_readl(pwm.base + REG_TCON);
	tcon &= ~TCON_START(channel);
	__raw_writel(tcon, pwm.base + REG_TCON);

	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
	}

	static void samsung_time_setup(unsigned int channel, unsigned long tcnt)
	{
	unsigned long tcon;
	unsigned long flags;
	unsigned int tcon_chan = channel;

	if (tcon_chan > 0)
	++tcon_chan;

	spin_lock_irqsave(&samsung_pwm_lock, flags);

	tcon = __raw_readl(pwm.base + REG_TCON);

	tcnt--;

	tcon &= ~(TCON_START(tcon_chan) \| TCON_AUTORELOAD(tcon_chan));
	tcon \|= TCON_MANUALUPDATE(tcon_chan);

	__raw_writel(tcnt, pwm.base + REG_TCNTB(channel));
	__raw_writel(tcnt, pwm.base + REG_TCMPB(channel));
	__raw_writel(tcon, pwm.base + REG_TCON);

	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
	}

	static void samsung_time_start(unsigned int channel, bool periodic)
	{
	unsigned long tcon;
	unsigned long flags;

	if (channel > 0)
	++channel;

	spin_lock_irqsave(&samsung_pwm_lock, flags);

	tcon = __raw_readl(pwm.base + REG_TCON);

	tcon &= ~TCON_MANUALUPDATE(channel);
	tcon \|= TCON_START(channel);

	if (periodic)
	tcon \|= TCON_AUTORELOAD(channel);
	else
	tcon &= ~TCON_AUTORELOAD(channel);

	__raw_writel(tcon, pwm.base + REG_TCON);

	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
	}

	static int samsung_set_next_event(unsigned long cycles,
	struct clock_event_device *evt)
	{
	samsung_time_setup(pwm.event_id, cycles);
	samsung_time_start(pwm.event_id, false);

	return 0;
	}

	static void samsung_timer_resume(void)
	{
	/* event timer restart */
	samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick);
	samsung_time_start(pwm.event_id, true);

	/* source timer restart */
	samsung_time_setup(pwm.source_id, pwm.tcnt_max);
	samsung_time_start(pwm.source_id, true);
	}

	static void samsung_set_mode(enum clock_event_mode mode,
	struct clock_event_device *evt)
	{
	samsung_time_stop(pwm.event_id);

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
	samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick);
	samsung_time_start(pwm.event_id, true);
	break;

	case CLOCK_EVT_MODE_ONESHOT:
	break;

	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
	break;

	case CLOCK_EVT_MODE_RESUME:
	samsung_timer_resume();
	break;
	}
	}

	static struct clock_event_device time_event_device = {
	.name = "samsung_event_timer",
	.features = CLOCK_EVT_FEAT_PERIODIC \| CLOCK_EVT_FEAT_ONESHOT,
	.rating = 200,
	.set_next_event = samsung_set_next_event,
	.set_mode = samsung_set_mode,
	};

	static irqreturn_t samsung_clock_event_isr(int irq, void *dev_id)
	{
	struct clock_event_device *evt = dev_id;

	if (pwm.variant.has_tint_cstat) {
	u32 mask = (1 << pwm.event_id);
	writel(mask \| (mask << 5), pwm.base + REG_TINT_CSTAT);
	}

	evt->event_handler(evt);

	return IRQ_HANDLED;
	}

	static struct irqaction samsung_clock_event_irq = {
	.name = "samsung_time_irq",
	.flags = IRQF_DISABLED \| IRQF_TIMER \| IRQF_IRQPOLL,
	.handler = samsung_clock_event_isr,
	.dev_id = &time_event_device,
	};

	static void __init samsung_clockevent_init(void)
	{
	unsigned long pclk;
	unsigned long clock_rate;
	unsigned int irq_number;

	pclk = clk_get_rate(pwm.timerclk);

	samsung_timer_set_prescale(pwm.event_id, pwm.tscaler_div);
	samsung_timer_set_divisor(pwm.event_id, pwm.tdiv);

	clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
	pwm.clock_count_per_tick = clock_rate / HZ;

	time_event_device.cpumask = cpumask_of(0);
	clockevents_config_and_register(&time_event_device, clock_rate, 1, -1);

	irq_number = pwm.irq[pwm.event_id];
	setup_irq(irq_number, &samsung_clock_event_irq);

	if (pwm.variant.has_tint_cstat) {
	u32 mask = (1 << pwm.event_id);
	writel(mask \| (mask << 5), pwm.base + REG_TINT_CSTAT);
	}
	}

	static void __iomem *samsung_timer_reg(void)
	{
	switch (pwm.source_id) {
	case 0:
	case 1:
	case 2:
	case 3:
	return pwm.base + pwm.source_id * 0x0c + 0x14;

	case 4:
	return pwm.base + 0x40;

	default:
	BUG();
	}
	}

	/*
	* Override the global weak sched_clock symbol with this
	* local implementation which uses the clocksource to get some
	* better resolution when scheduling the kernel. We accept that
	* this wraps around for now, since it is just a relative time
	* stamp. (Inspired by U300 implementation.)
	*/
	static u32 notrace samsung_read_sched_clock(void)
	{
	void __iomem *reg = samsung_timer_reg();

	if (!reg)
	return 0;

	return ~__raw_readl(reg);
	}

	static void __init samsung_clocksource_init(void)
	{
	void __iomem *reg = samsung_timer_reg();
	unsigned long pclk;
	unsigned long clock_rate;
	int ret;

	pclk = clk_get_rate(pwm.timerclk);

	samsung_timer_set_prescale(pwm.source_id, pwm.tscaler_div);
	samsung_timer_set_divisor(pwm.source_id, pwm.tdiv);

	clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);

	samsung_time_setup(pwm.source_id, pwm.tcnt_max);
	samsung_time_start(pwm.source_id, true);

	setup_sched_clock(samsung_read_sched_clock,
	pwm.variant.bits, clock_rate);

	ret = clocksource_mmio_init(reg, "samsung_clocksource_timer",
	clock_rate, 250, pwm.variant.bits,
	clocksource_mmio_readl_down);
	if (ret)
	panic("samsung_clocksource_timer: can't register clocksource\n");
	}

	static void __init samsung_timer_resources(void)
	{
	pwm.timerclk = clk_get(NULL, "timers");
	if (IS_ERR(pwm.timerclk))
	panic("failed to get timers clock for timer");

	clk_prepare_enable(pwm.timerclk);

	pwm.tcnt_max = (1UL << pwm.variant.bits) - 1;
	if (pwm.variant.bits == 16) {
	pwm.tscaler_div = 25;
	pwm.tdiv = 2;
	} else {
	pwm.tscaler_div = 2;
	pwm.tdiv = 1;
	}
	}

	/*
	* PWM master driver
	*/
	static void __init samsung_pwm_clocksource_init(void)
	{
	u8 mask;
	int channel;

	mask = ~pwm.variant.output_mask & ((1 << SAMSUNG_PWM_NUM) - 1);
	channel = fls(mask) - 1;
	if (channel < 0)
	panic("failed to find PWM channel for clocksource");
	pwm.source_id = channel;

	mask &= ~(1 << channel);
	channel = fls(mask) - 1;
	if (channel < 0)
	panic("failed to find PWM channel for clock event");
	pwm.event_id = channel;

	samsung_timer_resources();
	samsung_clockevent_init();
	samsung_clocksource_init();
	}

	static void __init samsung_pwm_alloc(struct device_node *np,
	const struct samsung_pwm_variant *variant)
	{
	struct resource res;
	struct property *prop;
	const __be32 *cur;
	u32 val;
	int i;

	memcpy(&pwm.variant, variant, sizeof(pwm.variant));
	for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
	pwm.irq[i] = irq_of_parse_and_map(np, i);

	of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
	if (val >= SAMSUNG_PWM_NUM) {
	pr_warning("%s: invalid channel index in samsung,pwm-outputs property\n",
	__func__);
	continue;
	}
	pwm.variant.output_mask \|= 1 << val;
	}

	of_address_to_resource(np, 0, &res);
	if (!request_mem_region(res.start,
	resource_size(&res), "samsung-pwm")) {
	pr_err("%s: failed to request IO mem region\n", __func__);
	return;
	}

	pwm.base = ioremap(res.start, resource_size(&res));
	if (!pwm.base) {
	pr_err("%s: failed to map PWM registers\n", __func__);
	release_mem_region(res.start, resource_size(&res));
	return;
	}

	samsung_pwm_clocksource_init();
	}

	static const struct samsung_pwm_variant s3c24xx_variant = {
	.bits = 16,
	.div_base = 1,
	.has_tint_cstat = false,
	.tclk_mask = (1 << 4),
	};

	static void __init s3c2410_pwm_clocksource_init(struct device_node *np)
	{
	samsung_pwm_alloc(np, &s3c24xx_variant);
	}
	CLOCKSOURCE_OF_DECLARE(s3c2410_pwm, "samsung,s3c2410-pwm", s3c2410_pwm_clocksource_init);

	static const struct samsung_pwm_variant s3c64xx_variant = {
	.bits = 32,
	.div_base = 0,
	.has_tint_cstat = true,
	.tclk_mask = (1 << 7) \| (1 << 6) \| (1 << 5),
	};

	static void __init s3c64xx_pwm_clocksource_init(struct device_node *np)
	{
	samsung_pwm_alloc(np, &s3c64xx_variant);
	}
	CLOCKSOURCE_OF_DECLARE(s3c6400_pwm, "samsung,s3c6400-pwm", s3c64xx_pwm_clocksource_init);

	static const struct samsung_pwm_variant s5p64x0_variant = {
	.bits = 32,
	.div_base = 0,
	.has_tint_cstat = true,
	.tclk_mask = 0,
	};

	static void __init s5p64x0_pwm_clocksource_init(struct device_node *np)
	{
	samsung_pwm_alloc(np, &s5p64x0_variant);
	}
	CLOCKSOURCE_OF_DECLARE(s5p6440_pwm, "samsung,s5p6440-pwm", s5p64x0_pwm_clocksource_init);

	static const struct samsung_pwm_variant s5p_variant = {
	.bits = 32,
	.div_base = 0,
	.has_tint_cstat = true,
	.tclk_mask = (1 << 5),
	};

	static void __init s5p_pwm_clocksource_init(struct device_node *np)
	{
	samsung_pwm_alloc(np, &s5p_variant);
	}
	CLOCKSOURCE_OF_DECLARE(s5pc100_pwm, "samsung,s5pc100-pwm", s5p_pwm_clocksource_init);