drivers/misc/ep93xx_pwm.c - kernel/msm-4.9 - Gitiles

 /*
  *  Simple PWM driver for EP93XX
  *
  *	(c) Copyright 2009  Matthieu Crapet <mcrapet@gmail.com>
  *	(c) Copyright 2009  H Hartley Sweeten <hsweeten@visionengravers.com>
  *
  *	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.
  *
  *  EP9307 has only one channel:
  *    - PWMOUT
  *
  *  EP9301/02/12/15 have two channels:
  *    - PWMOUT
  *    - PWMOUT1 (alternate function for EGPIO14)
  */

 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>

 #include <mach/platform.h>

 #define EP93XX_PWMx_TERM_COUNT	0x00
 #define EP93XX_PWMx_DUTY_CYCLE	0x04
 #define EP93XX_PWMx_ENABLE	0x08
 #define EP93XX_PWMx_INVERT	0x0C

 #define EP93XX_PWM_MAX_COUNT	0xFFFF

 struct ep93xx_pwm {
 	void __iomem	*mmio_base;
 	struct clk	*clk;
 	u32		duty_percent;
 };

 static inline void ep93xx_pwm_writel(struct ep93xx_pwm *pwm,
 		unsigned int val, unsigned int off)
 {
 	__raw_writel(val, pwm->mmio_base + off);
 }

 static inline unsigned int ep93xx_pwm_readl(struct ep93xx_pwm *pwm,
 		unsigned int off)
 {
 	return __raw_readl(pwm->mmio_base + off);
 }

 static inline void ep93xx_pwm_write_tc(struct ep93xx_pwm *pwm, u16 value)
 {
 	ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_TERM_COUNT);
 }

 static inline u16 ep93xx_pwm_read_tc(struct ep93xx_pwm *pwm)
 {
 	return ep93xx_pwm_readl(pwm, EP93XX_PWMx_TERM_COUNT);
 }

 static inline void ep93xx_pwm_write_dc(struct ep93xx_pwm *pwm, u16 value)
 {
 	ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_DUTY_CYCLE);
 }

 static inline void ep93xx_pwm_enable(struct ep93xx_pwm *pwm)
 {
 	ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_ENABLE);
 }

 static inline void ep93xx_pwm_disable(struct ep93xx_pwm *pwm)
 {
 	ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_ENABLE);
 }

 static inline int ep93xx_pwm_is_enabled(struct ep93xx_pwm *pwm)
 {
 	return ep93xx_pwm_readl(pwm, EP93XX_PWMx_ENABLE) & 0x1;
 }

 static inline void ep93xx_pwm_invert(struct ep93xx_pwm *pwm)
 {
 	ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_INVERT);
 }

 static inline void ep93xx_pwm_normal(struct ep93xx_pwm *pwm)
 {
 	ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_INVERT);
 }

 static inline int ep93xx_pwm_is_inverted(struct ep93xx_pwm *pwm)
 {
 	return ep93xx_pwm_readl(pwm, EP93XX_PWMx_INVERT) & 0x1;
 }

 /*
  * /sys/devices/platform/ep93xx-pwm.N
  *   /min_freq      read-only   minimum pwm output frequency
  *   /max_req       read-only   maximum pwm output frequency
  *   /freq          read-write  pwm output frequency (0 = disable output)
  *   /duty_percent  read-write  pwm duty cycle percent (1..99)
  *   /invert        read-write  invert pwm output
  */

 static ssize_t ep93xx_pwm_get_min_freq(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
 	unsigned long rate = clk_get_rate(pwm->clk);

 	return sprintf(buf, "%ld\n", rate / (EP93XX_PWM_MAX_COUNT + 1));
 }

 static ssize_t ep93xx_pwm_get_max_freq(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
 	unsigned long rate = clk_get_rate(pwm->clk);

 	return sprintf(buf, "%ld\n", rate / 2);
 }

 static ssize_t ep93xx_pwm_get_freq(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);

 	if (ep93xx_pwm_is_enabled(pwm)) {
 		unsigned long rate = clk_get_rate(pwm->clk);
 		u16 term = ep93xx_pwm_read_tc(pwm);

 		return sprintf(buf, "%ld\n", rate / (term + 1));
 	} else {
 		return sprintf(buf, "disabled\n");
 	}
 }

 static ssize_t ep93xx_pwm_set_freq(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
 	long val;
 	int err;

 	err = strict_strtol(buf, 10, &val);
 	if (err)
 		return -EINVAL;

 	if (val == 0) {
 		ep93xx_pwm_disable(pwm);
 	} else if (val <= (clk_get_rate(pwm->clk) / 2)) {
 		u32 term, duty;

 		val = (clk_get_rate(pwm->clk) / val) - 1;
 		if (val > EP93XX_PWM_MAX_COUNT)
 			val = EP93XX_PWM_MAX_COUNT;
 		if (val < 1)
 			val = 1;

 		term = ep93xx_pwm_read_tc(pwm);
 		duty = ((val + 1) * pwm->duty_percent / 100) - 1;

 		/* If pwm is running, order is important */
 		if (val > term) {
 			ep93xx_pwm_write_tc(pwm, val);
 			ep93xx_pwm_write_dc(pwm, duty);
 		} else {
 			ep93xx_pwm_write_dc(pwm, duty);
 			ep93xx_pwm_write_tc(pwm, val);
 		}

 		if (!ep93xx_pwm_is_enabled(pwm))
 			ep93xx_pwm_enable(pwm);
 	} else {
 		return -EINVAL;
 	}

 	return count;
 }

 static ssize_t ep93xx_pwm_get_duty_percent(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);

 	return sprintf(buf, "%d\n", pwm->duty_percent);
 }

 static ssize_t ep93xx_pwm_set_duty_percent(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
 	long val;
 	int err;

 	err = strict_strtol(buf, 10, &val);
 	if (err)
 		return -EINVAL;

 	if (val > 0 && val < 100) {
 		u32 term = ep93xx_pwm_read_tc(pwm);
 		ep93xx_pwm_write_dc(pwm, ((term + 1) * val / 100) - 1);
 		pwm->duty_percent = val;
 		return count;
 	}

 	return -EINVAL;
 }

 static ssize_t ep93xx_pwm_get_invert(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);

 	return sprintf(buf, "%d\n", ep93xx_pwm_is_inverted(pwm));
 }

 static ssize_t ep93xx_pwm_set_invert(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
 	long val;
 	int err;

 	err = strict_strtol(buf, 10, &val);
 	if (err)
 		return -EINVAL;

 	if (val == 0)
 		ep93xx_pwm_normal(pwm);
 	else if (val == 1)
 		ep93xx_pwm_invert(pwm);
 	else
 		return -EINVAL;

 	return count;
 }

 static DEVICE_ATTR(min_freq, S_IRUGO, ep93xx_pwm_get_min_freq, NULL);
 static DEVICE_ATTR(max_freq, S_IRUGO, ep93xx_pwm_get_max_freq, NULL);
 static DEVICE_ATTR(freq, S_IWUSR | S_IRUGO,
 		   ep93xx_pwm_get_freq, ep93xx_pwm_set_freq);
 static DEVICE_ATTR(duty_percent, S_IWUSR | S_IRUGO,
 		   ep93xx_pwm_get_duty_percent, ep93xx_pwm_set_duty_percent);
 static DEVICE_ATTR(invert, S_IWUSR | S_IRUGO,
 		   ep93xx_pwm_get_invert, ep93xx_pwm_set_invert);

 static struct attribute *ep93xx_pwm_attrs[] = {
 	&dev_attr_min_freq.attr,
 	&dev_attr_max_freq.attr,
 	&dev_attr_freq.attr,
 	&dev_attr_duty_percent.attr,
 	&dev_attr_invert.attr,
 	NULL
 };

 static const struct attribute_group ep93xx_pwm_sysfs_files = {
 	.attrs	= ep93xx_pwm_attrs,
 };

 static int __init ep93xx_pwm_probe(struct platform_device *pdev)
 {
 	struct ep93xx_pwm *pwm;
 	struct resource *res;
 	int err;

 	err = ep93xx_pwm_acquire_gpio(pdev);
 	if (err)
 		return err;

 	pwm = kzalloc(sizeof(struct ep93xx_pwm), GFP_KERNEL);
 	if (!pwm) {
 		err = -ENOMEM;
 		goto fail_no_mem;
 	}

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (res == NULL) {
 		err = -ENXIO;
 		goto fail_no_mem_resource;
 	}

 	res = request_mem_region(res->start, resource_size(res), pdev->name);
 	if (res == NULL) {
 		err = -EBUSY;
 		goto fail_no_mem_resource;
 	}

 	pwm->mmio_base = ioremap(res->start, resource_size(res));
 	if (pwm->mmio_base == NULL) {
 		err = -ENXIO;
 		goto fail_no_ioremap;
 	}

 	err = sysfs_create_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
 	if (err)
 		goto fail_no_sysfs;

 	pwm->clk = clk_get(&pdev->dev, "pwm_clk");
 	if (IS_ERR(pwm->clk)) {
 		err = PTR_ERR(pwm->clk);
 		goto fail_no_clk;
 	}

 	pwm->duty_percent = 50;

 	platform_set_drvdata(pdev, pwm);

 	/* disable pwm at startup. Avoids zero value. */
 	ep93xx_pwm_disable(pwm);
 	ep93xx_pwm_write_tc(pwm, EP93XX_PWM_MAX_COUNT);
 	ep93xx_pwm_write_dc(pwm, EP93XX_PWM_MAX_COUNT / 2);

 	clk_enable(pwm->clk);

 	return 0;

 fail_no_clk:
 	sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
 fail_no_sysfs:
 	iounmap(pwm->mmio_base);
 fail_no_ioremap:
 	release_mem_region(res->start, resource_size(res));
 fail_no_mem_resource:
 	kfree(pwm);
 fail_no_mem:
 	ep93xx_pwm_release_gpio(pdev);
 	return err;
 }

 static int __exit ep93xx_pwm_remove(struct platform_device *pdev)
 {
 	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

 	ep93xx_pwm_disable(pwm);
 	clk_disable(pwm->clk);
 	clk_put(pwm->clk);
 	platform_set_drvdata(pdev, NULL);
 	sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
 	iounmap(pwm->mmio_base);
 	release_mem_region(res->start, resource_size(res));
 	kfree(pwm);
 	ep93xx_pwm_release_gpio(pdev);

 	return 0;
 }

 static struct platform_driver ep93xx_pwm_driver = {
 	.driver		= {
 		.name	= "ep93xx-pwm",
 		.owner	= THIS_MODULE,
 	},
 	.remove		= __exit_p(ep93xx_pwm_remove),
 };

 static int __init ep93xx_pwm_init(void)
 {
 	return platform_driver_probe(&ep93xx_pwm_driver, ep93xx_pwm_probe);
 }

 static void __exit ep93xx_pwm_exit(void)
 {
 	platform_driver_unregister(&ep93xx_pwm_driver);
 }

 module_init(ep93xx_pwm_init);
 module_exit(ep93xx_pwm_exit);

 MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>, "
 	      "H Hartley Sweeten <hsweeten@visionengravers.com>");
 MODULE_DESCRIPTION("EP93xx PWM driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:ep93xx-pwm");
	/*
	* Simple PWM driver for EP93XX
	*
	* (c) Copyright 2009 Matthieu Crapet <mcrapet@gmail.com>
	* (c) Copyright 2009 H Hartley Sweeten <hsweeten@visionengravers.com>
	*
	* 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.
	*
	* EP9307 has only one channel:
	* - PWMOUT
	*
	* EP9301/02/12/15 have two channels:
	* - PWMOUT
	* - PWMOUT1 (alternate function for EGPIO14)
	*/

	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/io.h>

	#include <mach/platform.h>

	#define EP93XX_PWMx_TERM_COUNT 0x00
	#define EP93XX_PWMx_DUTY_CYCLE 0x04
	#define EP93XX_PWMx_ENABLE 0x08
	#define EP93XX_PWMx_INVERT 0x0C

	#define EP93XX_PWM_MAX_COUNT 0xFFFF

	struct ep93xx_pwm {
	void __iomem *mmio_base;
	struct clk *clk;
	u32 duty_percent;
	};

	static inline void ep93xx_pwm_writel(struct ep93xx_pwm *pwm,
	unsigned int val, unsigned int off)
	{
	__raw_writel(val, pwm->mmio_base + off);
	}

	static inline unsigned int ep93xx_pwm_readl(struct ep93xx_pwm *pwm,
	unsigned int off)
	{
	return __raw_readl(pwm->mmio_base + off);
	}

	static inline void ep93xx_pwm_write_tc(struct ep93xx_pwm *pwm, u16 value)
	{
	ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_TERM_COUNT);
	}

	static inline u16 ep93xx_pwm_read_tc(struct ep93xx_pwm *pwm)
	{
	return ep93xx_pwm_readl(pwm, EP93XX_PWMx_TERM_COUNT);
	}

	static inline void ep93xx_pwm_write_dc(struct ep93xx_pwm *pwm, u16 value)
	{
	ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_DUTY_CYCLE);
	}

	static inline void ep93xx_pwm_enable(struct ep93xx_pwm *pwm)
	{
	ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_ENABLE);
	}

	static inline void ep93xx_pwm_disable(struct ep93xx_pwm *pwm)
	{
	ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_ENABLE);
	}

	static inline int ep93xx_pwm_is_enabled(struct ep93xx_pwm *pwm)
	{
	return ep93xx_pwm_readl(pwm, EP93XX_PWMx_ENABLE) & 0x1;
	}

	static inline void ep93xx_pwm_invert(struct ep93xx_pwm *pwm)
	{
	ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_INVERT);
	}

	static inline void ep93xx_pwm_normal(struct ep93xx_pwm *pwm)
	{
	ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_INVERT);
	}

	static inline int ep93xx_pwm_is_inverted(struct ep93xx_pwm *pwm)
	{
	return ep93xx_pwm_readl(pwm, EP93XX_PWMx_INVERT) & 0x1;
	}

	/*
	* /sys/devices/platform/ep93xx-pwm.N
	* /min_freq read-only minimum pwm output frequency
	* /max_req read-only maximum pwm output frequency
	* /freq read-write pwm output frequency (0 = disable output)
	* /duty_percent read-write pwm duty cycle percent (1..99)
	* /invert read-write invert pwm output
	*/

	static ssize_t ep93xx_pwm_get_min_freq(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
	unsigned long rate = clk_get_rate(pwm->clk);

	return sprintf(buf, "%ld\n", rate / (EP93XX_PWM_MAX_COUNT + 1));
	}

	static ssize_t ep93xx_pwm_get_max_freq(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
	unsigned long rate = clk_get_rate(pwm->clk);

	return sprintf(buf, "%ld\n", rate / 2);
	}

	static ssize_t ep93xx_pwm_get_freq(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);

	if (ep93xx_pwm_is_enabled(pwm)) {
	unsigned long rate = clk_get_rate(pwm->clk);
	u16 term = ep93xx_pwm_read_tc(pwm);

	return sprintf(buf, "%ld\n", rate / (term + 1));
	} else {
	return sprintf(buf, "disabled\n");
	}
	}

	static ssize_t ep93xx_pwm_set_freq(struct device *dev,
	struct device_attribute attr, const char buf, size_t count)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
	long val;
	int err;

	err = strict_strtol(buf, 10, &val);
	if (err)
	return -EINVAL;

	if (val == 0) {
	ep93xx_pwm_disable(pwm);
	} else if (val <= (clk_get_rate(pwm->clk) / 2)) {
	u32 term, duty;

	val = (clk_get_rate(pwm->clk) / val) - 1;
	if (val > EP93XX_PWM_MAX_COUNT)
	val = EP93XX_PWM_MAX_COUNT;
	if (val < 1)
	val = 1;

	term = ep93xx_pwm_read_tc(pwm);
	duty = ((val + 1) * pwm->duty_percent / 100) - 1;

	/* If pwm is running, order is important */
	if (val > term) {
	ep93xx_pwm_write_tc(pwm, val);
	ep93xx_pwm_write_dc(pwm, duty);
	} else {
	ep93xx_pwm_write_dc(pwm, duty);
	ep93xx_pwm_write_tc(pwm, val);
	}

	if (!ep93xx_pwm_is_enabled(pwm))
	ep93xx_pwm_enable(pwm);
	} else {
	return -EINVAL;
	}

	return count;
	}

	static ssize_t ep93xx_pwm_get_duty_percent(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);

	return sprintf(buf, "%d\n", pwm->duty_percent);
	}

	static ssize_t ep93xx_pwm_set_duty_percent(struct device *dev,
	struct device_attribute attr, const char buf, size_t count)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
	long val;
	int err;

	err = strict_strtol(buf, 10, &val);
	if (err)
	return -EINVAL;

	if (val > 0 && val < 100) {
	u32 term = ep93xx_pwm_read_tc(pwm);
	ep93xx_pwm_write_dc(pwm, ((term + 1) * val / 100) - 1);
	pwm->duty_percent = val;
	return count;
	}

	return -EINVAL;
	}

	static ssize_t ep93xx_pwm_get_invert(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);

	return sprintf(buf, "%d\n", ep93xx_pwm_is_inverted(pwm));
	}

	static ssize_t ep93xx_pwm_set_invert(struct device *dev,
	struct device_attribute attr, const char buf, size_t count)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
	long val;
	int err;

	err = strict_strtol(buf, 10, &val);
	if (err)
	return -EINVAL;

	if (val == 0)
	ep93xx_pwm_normal(pwm);
	else if (val == 1)
	ep93xx_pwm_invert(pwm);
	else
	return -EINVAL;

	return count;
	}

	static DEVICE_ATTR(min_freq, S_IRUGO, ep93xx_pwm_get_min_freq, NULL);
	static DEVICE_ATTR(max_freq, S_IRUGO, ep93xx_pwm_get_max_freq, NULL);
	static DEVICE_ATTR(freq, S_IWUSR \| S_IRUGO,
	ep93xx_pwm_get_freq, ep93xx_pwm_set_freq);
	static DEVICE_ATTR(duty_percent, S_IWUSR \| S_IRUGO,
	ep93xx_pwm_get_duty_percent, ep93xx_pwm_set_duty_percent);
	static DEVICE_ATTR(invert, S_IWUSR \| S_IRUGO,
	ep93xx_pwm_get_invert, ep93xx_pwm_set_invert);

	static struct attribute *ep93xx_pwm_attrs[] = {
	&dev_attr_min_freq.attr,
	&dev_attr_max_freq.attr,
	&dev_attr_freq.attr,
	&dev_attr_duty_percent.attr,
	&dev_attr_invert.attr,
	NULL
	};

	static const struct attribute_group ep93xx_pwm_sysfs_files = {
	.attrs = ep93xx_pwm_attrs,
	};

	static int __init ep93xx_pwm_probe(struct platform_device *pdev)
	{
	struct ep93xx_pwm *pwm;
	struct resource *res;
	int err;

	err = ep93xx_pwm_acquire_gpio(pdev);
	if (err)
	return err;

	pwm = kzalloc(sizeof(struct ep93xx_pwm), GFP_KERNEL);
	if (!pwm) {
	err = -ENOMEM;
	goto fail_no_mem;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
	err = -ENXIO;
	goto fail_no_mem_resource;
	}

	res = request_mem_region(res->start, resource_size(res), pdev->name);
	if (res == NULL) {
	err = -EBUSY;
	goto fail_no_mem_resource;
	}

	pwm->mmio_base = ioremap(res->start, resource_size(res));
	if (pwm->mmio_base == NULL) {
	err = -ENXIO;
	goto fail_no_ioremap;
	}

	err = sysfs_create_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
	if (err)
	goto fail_no_sysfs;

	pwm->clk = clk_get(&pdev->dev, "pwm_clk");
	if (IS_ERR(pwm->clk)) {
	err = PTR_ERR(pwm->clk);
	goto fail_no_clk;
	}

	pwm->duty_percent = 50;

	platform_set_drvdata(pdev, pwm);

	/* disable pwm at startup. Avoids zero value. */
	ep93xx_pwm_disable(pwm);
	ep93xx_pwm_write_tc(pwm, EP93XX_PWM_MAX_COUNT);
	ep93xx_pwm_write_dc(pwm, EP93XX_PWM_MAX_COUNT / 2);

	clk_enable(pwm->clk);

	return 0;

	fail_no_clk:
	sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
	fail_no_sysfs:
	iounmap(pwm->mmio_base);
	fail_no_ioremap:
	release_mem_region(res->start, resource_size(res));
	fail_no_mem_resource:
	kfree(pwm);
	fail_no_mem:
	ep93xx_pwm_release_gpio(pdev);
	return err;
	}

	static int __exit ep93xx_pwm_remove(struct platform_device *pdev)
	{
	struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	ep93xx_pwm_disable(pwm);
	clk_disable(pwm->clk);
	clk_put(pwm->clk);
	platform_set_drvdata(pdev, NULL);
	sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
	iounmap(pwm->mmio_base);
	release_mem_region(res->start, resource_size(res));
	kfree(pwm);
	ep93xx_pwm_release_gpio(pdev);

	return 0;
	}

	static struct platform_driver ep93xx_pwm_driver = {
	.driver = {
	.name = "ep93xx-pwm",
	.owner = THIS_MODULE,
	},
	.remove = __exit_p(ep93xx_pwm_remove),
	};

	static int __init ep93xx_pwm_init(void)
	{
	return platform_driver_probe(&ep93xx_pwm_driver, ep93xx_pwm_probe);
	}

	static void __exit ep93xx_pwm_exit(void)
	{
	platform_driver_unregister(&ep93xx_pwm_driver);
	}

	module_init(ep93xx_pwm_init);
	module_exit(ep93xx_pwm_exit);

	MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>, "
	"H Hartley Sweeten <hsweeten@visionengravers.com>");
	MODULE_DESCRIPTION("EP93xx PWM driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:ep93xx-pwm");