arch/arm/plat-s3c24xx/pwm.c - kernel/msm-4.9 - Gitiles

 /* arch/arm/plat-s3c24xx/pwm.c
  *
  * Copyright (c) 2007 Ben Dooks
  * Copyright (c) 2008 Simtec Electronics
  *	Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
  *
  * S3C24XX PWM device core
  *
  * 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/module.h>
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/pwm.h>

 #include <asm/plat-s3c24xx/devs.h>
 #include <asm/plat-s3c/regs-timer.h>

 struct pwm_device {
 	struct list_head	 list;
 	struct platform_device	*pdev;

 	struct clk		*clk_div;
 	struct clk		*clk;
 	const char		*label;

 	unsigned int		 period_ns;
 	unsigned int		 duty_ns;

 	unsigned char		 tcon_base;
 	unsigned char		 running;
 	unsigned char		 use_count;
 	unsigned char		 pwm_id;
 };

 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)

 static struct clk *clk_scaler[2];

 /* Standard setup for a timer block. */

 #define TIMER_RESOURCE_SIZE (1)

 #define TIMER_RESOURCE(_tmr, _irq)			\
 	(struct resource [TIMER_RESOURCE_SIZE]) {	\
 		[0] = {					\
 			.start	= _irq,			\
 			.end	= _irq,			\
 			.flags	= IORESOURCE_IRQ	\
 		}					\
 	}

 #define DEFINE_TIMER(_tmr_no, _irq)			\
 	.name		= "s3c24xx-pwm",		\
 	.id		= _tmr_no,			\
 	.num_resources	= TIMER_RESOURCE_SIZE,		\
 	.resource	= TIMER_RESOURCE(_tmr_no, _irq),	\

 /* since we already have an static mapping for the timer, we do not
  * bother setting any IO resource for the base.
  */

 struct platform_device s3c_device_timer[] = {
 	[0] = { DEFINE_TIMER(0, IRQ_TIMER0) },
 	[1] = { DEFINE_TIMER(1, IRQ_TIMER1) },
 	[2] = { DEFINE_TIMER(2, IRQ_TIMER2) },
 	[3] = { DEFINE_TIMER(3, IRQ_TIMER3) },
 	[4] = { DEFINE_TIMER(4, IRQ_TIMER4) },
 };

 static inline int pwm_is_tdiv(struct pwm_device *pwm)
 {
 	return clk_get_parent(pwm->clk) == pwm->clk_div;
 }

 static DEFINE_MUTEX(pwm_lock);
 static LIST_HEAD(pwm_list);

 struct pwm_device *pwm_request(int pwm_id, const char *label)
 {
 	struct pwm_device *pwm;
 	int found = 0;

 	mutex_lock(&pwm_lock);

 	list_for_each_entry(pwm, &pwm_list, list) {
 		if (pwm->pwm_id == pwm_id) {
 			found = 1;
 			break;
 		}
 	}

 	if (found) {
 		if (pwm->use_count == 0) {
 			pwm->use_count = 1;
 			pwm->label = label;
 		} else
 			pwm = ERR_PTR(-EBUSY);
 	} else
 		pwm = ERR_PTR(-ENOENT);

 	mutex_unlock(&pwm_lock);
 	return pwm;
 }

 EXPORT_SYMBOL(pwm_request);


 void pwm_free(struct pwm_device *pwm)
 {
 	mutex_lock(&pwm_lock);

 	if (pwm->use_count) {
 		pwm->use_count--;
 		pwm->label = NULL;
 	} else
 		printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);

 	mutex_unlock(&pwm_lock);
 }

 EXPORT_SYMBOL(pwm_free);

 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))

 int pwm_enable(struct pwm_device *pwm)
 {
 	unsigned long flags;
 	unsigned long tcon;

 	local_irq_save(flags);

 	tcon = __raw_readl(S3C2410_TCON);
 	tcon |= pwm_tcon_start(pwm);
 	__raw_writel(tcon, S3C2410_TCON);

 	local_irq_restore(flags);

 	pwm->running = 1;
 	return 0;
 }

 EXPORT_SYMBOL(pwm_enable);

 void pwm_disable(struct pwm_device *pwm)
 {
 	unsigned long flags;
 	unsigned long tcon;

 	local_irq_save(flags);

 	tcon = __raw_readl(S3C2410_TCON);
 	tcon &= ~pwm_tcon_start(pwm);
 	__raw_writel(tcon, S3C2410_TCON);

 	local_irq_restore(flags);

 	pwm->running = 0;
 }

 EXPORT_SYMBOL(pwm_disable);

 static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
 {
 	unsigned long tin_parent_rate;
 	unsigned int div;

 	tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
 	pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);

 	for (div = 2; div <= 16; div *= 2) {
 		if ((tin_parent_rate / (div << 16)) < freq)
 			return tin_parent_rate / div;
 	}

 	return tin_parent_rate / 16;
 }

 #define NS_IN_HZ (1000000000UL)

 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 {
 	unsigned long tin_rate;
 	unsigned long tin_ns;
 	unsigned long period;
 	unsigned long flags;
 	unsigned long tcon;
 	unsigned long tcnt;
 	long tcmp;

 	/* We currently avoid using 64bit arithmetic by using the
 	 * fact that anything faster than 1Hz is easily representable
 	 * by 32bits. */

 	if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 		return -ERANGE;

 	if (duty_ns > period_ns)
 		return -EINVAL;

 	if (period_ns == pwm->period_ns &&
 	    duty_ns == pwm->duty_ns)
 		return 0;

 	/* The TCMP and TCNT can be read without a lock, they're not
 	 * shared between the timers. */

 	tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
 	tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));

 	period = NS_IN_HZ / period_ns;

 	pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
 		duty_ns, period_ns, period);

 	/* Check to see if we are changing the clock rate of the PWM */

 	if (pwm->period_ns != period_ns) {
 		if (pwm_is_tdiv(pwm)) {
 			tin_rate = pwm_calc_tin(pwm, period);
 			clk_set_rate(pwm->clk_div, tin_rate);
 		} else
 			tin_rate = clk_get_rate(pwm->clk);

 		pwm->period_ns = period_ns;

 		pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);

 		tin_ns = NS_IN_HZ / tin_rate;
 		tcnt = period_ns / tin_ns;
 	} else
 		tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);

 	/* Note, counters count down */

 	tcmp = duty_ns / tin_ns;
 	tcmp = tcnt - tcmp;

 	pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);

 	if (tcmp < 0)
 		tcmp = 0;

 	/* Update the PWM register block. */

 	local_irq_save(flags);

 	__raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
 	__raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));

 	tcon = __raw_readl(S3C2410_TCON);
 	tcon |= pwm_tcon_manulupdate(pwm);
 	tcon |= pwm_tcon_autoreload(pwm);
 	__raw_writel(tcon, S3C2410_TCON);

 	tcon &= ~pwm_tcon_manulupdate(pwm);
 	__raw_writel(tcon, S3C2410_TCON);

 	local_irq_restore(flags);

 	return 0;
 }

 EXPORT_SYMBOL(pwm_config);

 static int pwm_register(struct pwm_device *pwm)
 {
 	pwm->duty_ns = -1;
 	pwm->period_ns = -1;

 	mutex_lock(&pwm_lock);
 	list_add_tail(&pwm->list, &pwm_list);
 	mutex_unlock(&pwm_lock);

 	return 0;
 }

 static int s3c_pwm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct pwm_device *pwm;
 	unsigned long flags;
 	unsigned long tcon;
 	unsigned int id = pdev->id;
 	int ret;

 	if (id == 4) {
 		dev_err(dev, "TIMER4 is currently not supported\n");
 		return -ENXIO;
 	}

 	pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 	if (pwm == NULL) {
 		dev_err(dev, "failed to allocate pwm_device\n");
 		return -ENOMEM;
 	}

 	pwm->pdev = pdev;
 	pwm->pwm_id = id;

 	/* calculate base of control bits in TCON */
 	pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;

 	pwm->clk = clk_get(dev, "pwm-tin");
 	if (IS_ERR(pwm->clk)) {
 		dev_err(dev, "failed to get pwm tin clk\n");
 		ret = PTR_ERR(pwm->clk);
 		goto err_alloc;
 	}

 	pwm->clk_div = clk_get(dev, "pwm-tdiv");
 	if (IS_ERR(pwm->clk_div)) {
 		dev_err(dev, "failed to get pwm tdiv clk\n");
 		ret = PTR_ERR(pwm->clk_div);
 		goto err_clk_tin;
 	}

 	local_irq_save(flags);

 	tcon = __raw_readl(S3C2410_TCON);
 	tcon |= pwm_tcon_invert(pwm);
 	__raw_writel(tcon, S3C2410_TCON);

 	local_irq_restore(flags);


 	ret = pwm_register(pwm);
 	if (ret) {
 		dev_err(dev, "failed to register pwm\n");
 		goto err_clk_tdiv;
 	}

 	pwm_dbg(pwm, "config bits %02x\n",
 		(__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);

 	dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 		 clk_get_rate(pwm->clk),
 		 clk_get_rate(pwm->clk_div),
 		 pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);

 	platform_set_drvdata(pdev, pwm);
 	return 0;

  err_clk_tdiv:
 	clk_put(pwm->clk_div);

  err_clk_tin:
 	clk_put(pwm->clk);

  err_alloc:
 	kfree(pwm);
 	return ret;
 }

 static int s3c_pwm_remove(struct platform_device *pdev)
 {
 	struct pwm_device *pwm = platform_get_drvdata(pdev);

 	clk_put(pwm->clk_div);
 	clk_put(pwm->clk);
 	kfree(pwm);

 	return 0;
 }

 static struct platform_driver s3c_pwm_driver = {
 	.driver		= {
 		.name	= "s3c24xx-pwm",
 		.owner	= THIS_MODULE,
 	},
 	.probe		= s3c_pwm_probe,
 	.remove		= __devexit_p(s3c_pwm_remove),
 };

 static int __init pwm_init(void)
 {
 	int ret;

 	clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 	clk_scaler[1] = clk_get(NULL, "pwm-scaler1");

 	if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 		printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
 		return -EINVAL;
 	}

 	ret = platform_driver_register(&s3c_pwm_driver);
 	if (ret)
 		printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);

 	return ret;
 }

 arch_initcall(pwm_init);
	/* arch/arm/plat-s3c24xx/pwm.c
	*
	* Copyright (c) 2007 Ben Dooks
	* Copyright (c) 2008 Simtec Electronics
	* Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
	*
	* S3C24XX PWM device core
	*
	* 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/module.h>
	#include <linux/kernel.h>
	#include <linux/platform_device.h>
	#include <linux/err.h>
	#include <linux/clk.h>
	#include <linux/io.h>
	#include <linux/pwm.h>

	#include <asm/plat-s3c24xx/devs.h>
	#include <asm/plat-s3c/regs-timer.h>

	struct pwm_device {
	struct list_head list;
	struct platform_device *pdev;

	struct clk *clk_div;
	struct clk *clk;
	const char *label;

	unsigned int period_ns;
	unsigned int duty_ns;

	unsigned char tcon_base;
	unsigned char running;
	unsigned char use_count;
	unsigned char pwm_id;
	};

	#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)

	static struct clk *clk_scaler[2];

	/* Standard setup for a timer block. */

	#define TIMER_RESOURCE_SIZE (1)

	#define TIMER_RESOURCE(_tmr, _irq) \
	(struct resource [TIMER_RESOURCE_SIZE]) { \
	[0] = { \
	.start = _irq, \
	.end = _irq, \
	.flags = IORESOURCE_IRQ \
	} \
	}

	#define DEFINE_TIMER(_tmr_no, _irq) \
	.name = "s3c24xx-pwm", \
	.id = _tmr_no, \
	.num_resources = TIMER_RESOURCE_SIZE, \
	.resource = TIMER_RESOURCE(_tmr_no, _irq), \

	/* since we already have an static mapping for the timer, we do not
	* bother setting any IO resource for the base.
	*/

	struct platform_device s3c_device_timer[] = {
	[0] = { DEFINE_TIMER(0, IRQ_TIMER0) },
	[1] = { DEFINE_TIMER(1, IRQ_TIMER1) },
	[2] = { DEFINE_TIMER(2, IRQ_TIMER2) },
	[3] = { DEFINE_TIMER(3, IRQ_TIMER3) },
	[4] = { DEFINE_TIMER(4, IRQ_TIMER4) },
	};

	static inline int pwm_is_tdiv(struct pwm_device *pwm)
	{
	return clk_get_parent(pwm->clk) == pwm->clk_div;
	}

	static DEFINE_MUTEX(pwm_lock);
	static LIST_HEAD(pwm_list);

	struct pwm_device pwm_request(int pwm_id, const char label)
	{
	struct pwm_device *pwm;
	int found = 0;

	mutex_lock(&pwm_lock);

	list_for_each_entry(pwm, &pwm_list, list) {
	if (pwm->pwm_id == pwm_id) {
	found = 1;
	break;
	}
	}

	if (found) {
	if (pwm->use_count == 0) {
	pwm->use_count = 1;
	pwm->label = label;
	} else
	pwm = ERR_PTR(-EBUSY);
	} else
	pwm = ERR_PTR(-ENOENT);

	mutex_unlock(&pwm_lock);
	return pwm;
	}

	EXPORT_SYMBOL(pwm_request);


	void pwm_free(struct pwm_device *pwm)
	{
	mutex_lock(&pwm_lock);

	if (pwm->use_count) {
	pwm->use_count--;
	pwm->label = NULL;
	} else
	printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);

	mutex_unlock(&pwm_lock);
	}

	EXPORT_SYMBOL(pwm_free);

	#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
	#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
	#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
	#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))

	int pwm_enable(struct pwm_device *pwm)
	{
	unsigned long flags;
	unsigned long tcon;

	local_irq_save(flags);

	tcon = __raw_readl(S3C2410_TCON);
	tcon \|= pwm_tcon_start(pwm);
	__raw_writel(tcon, S3C2410_TCON);

	local_irq_restore(flags);

	pwm->running = 1;
	return 0;
	}

	EXPORT_SYMBOL(pwm_enable);

	void pwm_disable(struct pwm_device *pwm)
	{
	unsigned long flags;
	unsigned long tcon;

	local_irq_save(flags);

	tcon = __raw_readl(S3C2410_TCON);
	tcon &= ~pwm_tcon_start(pwm);
	__raw_writel(tcon, S3C2410_TCON);

	local_irq_restore(flags);

	pwm->running = 0;
	}

	EXPORT_SYMBOL(pwm_disable);

	static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
	{
	unsigned long tin_parent_rate;
	unsigned int div;

	tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
	pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);

	for (div = 2; div <= 16; div *= 2) {
	if ((tin_parent_rate / (div << 16)) < freq)
	return tin_parent_rate / div;
	}

	return tin_parent_rate / 16;
	}

	#define NS_IN_HZ (1000000000UL)

	int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
	{
	unsigned long tin_rate;
	unsigned long tin_ns;
	unsigned long period;
	unsigned long flags;
	unsigned long tcon;
	unsigned long tcnt;
	long tcmp;

	/* We currently avoid using 64bit arithmetic by using the
	* fact that anything faster than 1Hz is easily representable
	* by 32bits. */

	if (period_ns > NS_IN_HZ \|\| duty_ns > NS_IN_HZ)
	return -ERANGE;

	if (duty_ns > period_ns)
	return -EINVAL;

	if (period_ns == pwm->period_ns &&
	duty_ns == pwm->duty_ns)
	return 0;

	/* The TCMP and TCNT can be read without a lock, they're not
	* shared between the timers. */

	tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
	tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));

	period = NS_IN_HZ / period_ns;

	pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
	duty_ns, period_ns, period);

	/* Check to see if we are changing the clock rate of the PWM */

	if (pwm->period_ns != period_ns) {
	if (pwm_is_tdiv(pwm)) {
	tin_rate = pwm_calc_tin(pwm, period);
	clk_set_rate(pwm->clk_div, tin_rate);
	} else
	tin_rate = clk_get_rate(pwm->clk);

	pwm->period_ns = period_ns;

	pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);

	tin_ns = NS_IN_HZ / tin_rate;
	tcnt = period_ns / tin_ns;
	} else
	tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);

	/* Note, counters count down */

	tcmp = duty_ns / tin_ns;
	tcmp = tcnt - tcmp;

	pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);

	if (tcmp < 0)
	tcmp = 0;

	/* Update the PWM register block. */

	local_irq_save(flags);

	__raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
	__raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));

	tcon = __raw_readl(S3C2410_TCON);
	tcon \|= pwm_tcon_manulupdate(pwm);
	tcon \|= pwm_tcon_autoreload(pwm);
	__raw_writel(tcon, S3C2410_TCON);

	tcon &= ~pwm_tcon_manulupdate(pwm);
	__raw_writel(tcon, S3C2410_TCON);

	local_irq_restore(flags);

	return 0;
	}

	EXPORT_SYMBOL(pwm_config);

	static int pwm_register(struct pwm_device *pwm)
	{
	pwm->duty_ns = -1;
	pwm->period_ns = -1;

	mutex_lock(&pwm_lock);
	list_add_tail(&pwm->list, &pwm_list);
	mutex_unlock(&pwm_lock);

	return 0;
	}

	static int s3c_pwm_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct pwm_device *pwm;
	unsigned long flags;
	unsigned long tcon;
	unsigned int id = pdev->id;
	int ret;

	if (id == 4) {
	dev_err(dev, "TIMER4 is currently not supported\n");
	return -ENXIO;
	}

	pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
	if (pwm == NULL) {
	dev_err(dev, "failed to allocate pwm_device\n");
	return -ENOMEM;
	}

	pwm->pdev = pdev;
	pwm->pwm_id = id;

	/* calculate base of control bits in TCON */
	pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;

	pwm->clk = clk_get(dev, "pwm-tin");
	if (IS_ERR(pwm->clk)) {
	dev_err(dev, "failed to get pwm tin clk\n");
	ret = PTR_ERR(pwm->clk);
	goto err_alloc;
	}

	pwm->clk_div = clk_get(dev, "pwm-tdiv");
	if (IS_ERR(pwm->clk_div)) {
	dev_err(dev, "failed to get pwm tdiv clk\n");
	ret = PTR_ERR(pwm->clk_div);
	goto err_clk_tin;
	}

	local_irq_save(flags);

	tcon = __raw_readl(S3C2410_TCON);
	tcon \|= pwm_tcon_invert(pwm);
	__raw_writel(tcon, S3C2410_TCON);

	local_irq_restore(flags);


	ret = pwm_register(pwm);
	if (ret) {
	dev_err(dev, "failed to register pwm\n");
	goto err_clk_tdiv;
	}

	pwm_dbg(pwm, "config bits %02x\n",
	(__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);

	dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
	clk_get_rate(pwm->clk),
	clk_get_rate(pwm->clk_div),
	pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);

	platform_set_drvdata(pdev, pwm);
	return 0;

	err_clk_tdiv:
	clk_put(pwm->clk_div);

	err_clk_tin:
	clk_put(pwm->clk);

	err_alloc:
	kfree(pwm);
	return ret;
	}

	static int s3c_pwm_remove(struct platform_device *pdev)
	{
	struct pwm_device *pwm = platform_get_drvdata(pdev);

	clk_put(pwm->clk_div);
	clk_put(pwm->clk);
	kfree(pwm);

	return 0;
	}

	static struct platform_driver s3c_pwm_driver = {
	.driver = {
	.name = "s3c24xx-pwm",
	.owner = THIS_MODULE,
	},
	.probe = s3c_pwm_probe,
	.remove = __devexit_p(s3c_pwm_remove),
	};

	static int __init pwm_init(void)
	{
	int ret;

	clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
	clk_scaler[1] = clk_get(NULL, "pwm-scaler1");

	if (IS_ERR(clk_scaler[0]) \|\| IS_ERR(clk_scaler[1])) {
	printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
	return -EINVAL;
	}

	ret = platform_driver_register(&s3c_pwm_driver);
	if (ret)
	printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);

	return ret;
	}

	arch_initcall(pwm_init);